WO2024014404A1 - Power converter - Google Patents

Power converter Download PDF

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Publication number
WO2024014404A1
WO2024014404A1 PCT/JP2023/025240 JP2023025240W WO2024014404A1 WO 2024014404 A1 WO2024014404 A1 WO 2024014404A1 JP 2023025240 W JP2023025240 W JP 2023025240W WO 2024014404 A1 WO2024014404 A1 WO 2024014404A1
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WO
WIPO (PCT)
Prior art keywords
leg
power storage
voltage
switching
voltage source
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Application number
PCT/JP2023/025240
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French (fr)
Japanese (ja)
Inventor
一成 守屋
偉佳 楊
Original Assignee
Ａｚａｐａ株式会社
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Application filed by Ａｚａｐａ株式会社 filed Critical Ａｚａｐａ株式会社
Publication of WO2024014404A1 publication Critical patent/WO2024014404A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483—Converters with outputs that each can have more than two voltages levels
    • H02M7/49—Combination of the output voltage waveforms of a plurality of converters

Definitions

  • the present invention relates to a power conversion device that performs power conversion.
  • modular multilevel converters which combine modules in which multiple unit modules are connected in series, have been used as inverters that perform DC-AC conversion (for example, see Patent Document 1).
  • a modular multilevel converter is capable of outputting an arbitrary output voltage by adding the terminal voltages of capacitors included in a unit module.
  • An inverter using a modular multilevel converter is suitably used in electric vehicles such as electric cars and hybrid cars.
  • An object of the present invention is to provide a power conversion device that makes it easy to appropriately charge the power storage unit of a unit module.
  • the power conversion device includes an upper arm, an inductor, and a lower arm, which include a leg connected in series in this order, a series circuit in which a plurality of power storage blocks are connected in series, and are connected in parallel with the leg.
  • each of the upper arm and the lower arm includes a series circuit in which a plurality of unit modules are connected in series, and each of the unit modules has a first terminal and a second terminal.
  • a first power storage unit that stores charge
  • a first power storage unit that switches connection states including a connected state in which the first power storage unit is connected to the first and second terminals and a disconnected state in which the first and second terminals are short-circuited.
  • each of the electricity storage blocks includes a third and fourth terminal, a second electricity storage unit that stores charge, a connected state that connects the second electricity storage unit to the third and fourth terminals; a second switching circuit that switches connection states including a disconnection state that short-circuits between the third and fourth terminals, and the control unit controls switching of the connection state by each of the first switching circuits. Transfer of electric charge between the DC voltage source and the leg by causing the leg to output a predetermined power and controlling switching of the connection state by each of the first switching circuit and/or the second switching circuit. control.
  • the first power storage units of the unit modules that are in the joined state are connected in series, and the first power storage units of the unit modules that are in the detached state are not connected in series. Therefore, the first switching circuit makes it possible to control the voltage of the leg by increasing or decreasing the number of unit modules in the joined state.
  • the second power storage units of the power storage blocks that are in the joining state are connected in series, and the second power storage units of the power storage blocks that are in the detached state are not connected in series. Therefore, the first switching circuit makes it possible to control the voltage of the leg by increasing or decreasing the number of unit modules in the joined state.
  • the second switching circuit makes it possible to control the voltage of the DC voltage source by increasing or decreasing the number of power storage blocks in the joined state.
  • the leg and the DC voltage source are connected in parallel, if the voltage of the DC voltage source is made relatively higher than the voltage of the leg, charge will be transferred from the DC voltage source to the leg and the unit module of the leg will be charged. can do. Therefore, it becomes easy to appropriately charge the power storage section of the unit module.
  • each of the first power storage unit and each of the second power storage unit is a secondary battery, and each of the second power storage units has a larger power storage capacity than each of the first power storage unit.
  • the first power storage unit in the leg that outputs power to the outside may have a smaller power storage capacity than the second power storage unit. It becomes easy to use the battery as the first power storage unit.
  • each of the first power storage units has a higher current rating than each of the second power storage units.
  • the electric charge corresponding to the average power is transferred from the second power storage unit of the DC voltage source to the leg, and the first power storage unit in the leg It becomes easy to charge the parts.
  • control unit controls switching of the connection state by each of the first switching circuits and/or each of the second switching circuits so as to relatively increase the voltage of the DC voltage source.
  • charge is transferred from a voltage source to said leg.
  • the control unit can increase the voltage of the DC voltage source by increasing the number of power storage blocks in the subscribed state, and reduce the voltage of the leg by decreasing the number of unit modules in the subscribed state. be able to. Therefore, the control unit controls switching of the connection state by each first switching circuit and/or each second switching circuit to relatively increase the voltage of the DC voltage source, thereby transferring electric charge from the DC voltage source to the leg. It can be moved.
  • control unit controls each of the first switching circuits and/or each of the first switching circuits and/or each of the first switching circuits so that substantially the same amount of charge as the amount of charge outputted from the leg to the outside is transferred from the DC voltage source to the leg.
  • switching of the connection state is controlled by two switching circuits.
  • the control unit when the total open end voltage of the first power storage unit included in the leg is lower than a preset first reference voltage, the control unit relatively increases the output voltage of the DC voltage source. It is preferable that charges be transferred from the DC voltage source to the leg by controlling switching of the connection state by each of the first switching circuits and/or each of the second switching circuits so as to move the charge from the DC voltage source to the leg.
  • the open circuit voltage decreases. Therefore, when the total open end voltage of the first power storage unit included in the leg is lower than the first reference voltage, the output voltage of the DC voltage source is relatively increased to move the charge from the DC voltage source to the leg. This allows the leg to continue outputting power to the outside.
  • control unit controls switching of the connection state by each of the first switching circuits and/or each of the second switching circuits so as to relatively reduce the voltage of the DC voltage source.
  • charge is transferred from the DC voltage source to the DC voltage source.
  • the control unit can lower the voltage of the DC voltage source by decreasing the number of power storage blocks in the subscribed state, and increase the voltage of the leg by increasing the number of unit modules in the subscribed state. be able to. Therefore, the control unit controls switching of the connection state by each first switching circuit and/or each second switching circuit to relatively lower the voltage of the DC voltage source, thereby transferring electric charge from the leg to the DC voltage source. It can be moved.
  • control unit controls each of the first switching circuits and/or each of the first switching circuits and/or each of the first switching circuits so as to transfer substantially the same amount of charge from the leg to the DC voltage source as the amount of charge input from the outside to the leg.
  • switching of the connection state is controlled by two switching circuits.
  • power may be input to the leg from the outside, such as regenerated power from a motor.
  • power may be input to the leg from the outside, such as regenerated power from a motor.
  • it is possible to transfer approximately the same amount of charge from the leg to the DC voltage source as the amount of charge input from the outside to the leg, making it possible to continue receiving power from the outside. .
  • the control unit when the total open end voltage of the first power storage unit included in the leg exceeds a preset second reference voltage, the control unit relatively reduces the output voltage of the DC voltage source. It is preferable that charges be transferred from the leg to the DC voltage source by controlling switching of the connection state by each of the first switching circuit and/or each of the second switching circuit so as to cause the charge to move from the leg to the DC voltage source.
  • the open circuit voltage increases. Therefore, when the total open end voltage of the first power storage unit included in the leg exceeds the second reference voltage, the output voltage of the DC voltage source is relatively lowered to move the charge from the leg to the DC voltage source. This allows the leg to continue receiving power from the outside.
  • control unit further controls power conversion by the leg by changing a ratio between the voltage of the upper arm in the leg and the voltage of the lower arm in the leg.
  • the ratio between the voltage of the upper arm within the leg and the voltage of the lower arm within the leg can be changed independently of the voltage across the leg. Therefore, according to this configuration, it is possible to change the output voltage of the leg independently of the voltage across the leg and perform power conversion. As a result, it becomes possible to perform the power conversion operation by the leg and the movement of charge between the DC voltage source and the leg in parallel.
  • each of the first switching circuits is preferably a half-bridge or full-bridge bridge circuit
  • each of the second switching circuits is preferably a half-bridge or full-bridge bridge circuit.
  • the first switching circuit of the half-bridge can switch the connection state of the unit module between an joining state and a detached state.
  • the full-bridge first switching circuit switches the connection state of the unit module to a joining state and a disconnecting state, as well as an inverted state in which the first power storage unit is connected to the first and second terminals with polarity opposite to the joining state. be able to.
  • the second switching circuit of the half-bridge can switch the connection state of the power storage block between an joining state and a detached state.
  • the second switching circuit of the full bridge switches the connection state of the power storage block, in addition to the joining state and the detached state, to an inverted state in which the second power storage unit is connected to the third and fourth terminals with polarity opposite to the joining state. be able to.
  • the plurality of legs are provided, and the plurality of legs are connected in parallel, and the control unit further compares the total value of the open end voltage of the first power storage unit included in each of the legs, and relatively By controlling the switching of the connection state by the first switching circuit of each leg so as to relatively increase the voltage of the leg having a relatively large total value, the voltage of the leg having a relatively large total value increases. It is preferable to move the charge to the leg having the smaller total value.
  • the three legs are provided, and the three legs are connected in parallel to each other to form a three-phase inverter.
  • the power conversion device having such a configuration, it is easy to appropriately charge the power storage unit of the unit module.
  • FIG. 1 is a block diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention.
  • 2 is a conceptual circuit diagram showing an example of the configuration of a unit module EM and a power storage block BB shown in FIG. 1.
  • FIG. It is a conceptual circuit diagram showing an example of a unit module EM and a power storage block BB using full bridges as a first switching circuit and a second switching circuit.
  • 2 is a flowchart showing an example of an operation related to output control of the power conversion device shown in FIG. 1.
  • FIG. 2 is a flowchart showing an example of an operation related to regeneration control of the power converter shown in FIG. 1.
  • FIG. 2 is a flowchart showing an example of an operation related to balance control of the power conversion device shown in FIG. 1.
  • FIG. 1 is a block diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention.
  • FIG. 2 is a conceptual circuit diagram showing an example of the configuration of a unit module
  • FIG. 2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1.
  • FIG. 2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1.
  • FIG. 2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1.
  • FIG. 2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1.
  • FIG. 1 is a block diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention.
  • the power conversion device 1 shown in FIG. 1 roughly includes legs 2u, 2v, and 2w, a DC voltage source 4, a capacitor C, a control unit 5, a current sensor 7, and external terminals Tu, Tv, and Tw. It is equipped with The legs 2u, 2v, and 2w are connected in parallel to form a three-phase inverter 6.
  • the three-phase inverter 6, the capacitor C, and the DC voltage source 4 are connected in parallel by a power line WH on the high potential side and a power line WL on the low potential side.
  • the current sensor 7 detects the current flowing between the DC voltage source 4 and the three-phase inverter 6, and transmits the current value to the control unit 5.
  • Capacitor C performs smoothing, voltage stabilization, etc. Note that the power conversion device 1 does not necessarily need to include the capacitor C, and does not necessarily need to include the current sensor 7.
  • leg 2u is configured by an upper arm 3H, an inductor L, and a lower arm 3L connected in series in this order.
  • Legs 2v and 2w are configured similarly to leg 2u, so a description thereof will be omitted.
  • legs 2u, 2v, and 2w will be collectively referred to as leg 2.
  • the midpoint of inductor L of leg 2u is connected to external terminal Tu
  • the midpoint of inductor L of leg 2v is connected to external terminal Tv
  • the midpoint of inductor L of leg 2w is connected to external terminal Tw.
  • the external terminals Tu, Tv, and Tw function as three-phase power output terminals or three-phase regenerative current input terminals of the power conversion device 1.
  • Various three-phase power loads such as a three-phase motor, can be connected to the external terminals Tu, Tv, and Tw, and the power conversion device 1 may be mounted on an electric vehicle.
  • the inductor L may be, for example, a reactor with a center tap, or may be one in which two inductors are connected in series and their connection points are connected to external terminals Tu, Tv, and Tw.
  • Each of the upper arm 3H and the lower arm 3L includes a series circuit in which a plurality of unit modules EM are connected in series.
  • the upper arm 3H and the lower arm 3L are composed of only a series circuit in which a plurality of unit modules EM are connected in series, but the upper arm 3H and the lower arm 3L are It is only necessary to include the series circuit of the module EM, and it may include something other than the series circuit of the unit module EM.
  • the DC voltage source 4 includes a series circuit in which a plurality of power storage blocks BB are connected in series.
  • the DC voltage source 4 is configured only from a series circuit in which a plurality of power storage blocks BB are connected in series. It is sufficient that the circuit includes a circuit other than the series circuit of the power storage block BB.
  • FIG. 2 is a conceptual circuit diagram showing an example of the configuration of the unit module EM and power storage block BB shown in FIG. 1.
  • the symbols of the configurations related to the power storage block BB are shown in parentheses.
  • the unit module EM of leg 2 includes a terminal T1 (first terminal), a terminal T2 (second terminal), a first power storage unit B1 that stores electric charge, and an electrical connection of the first power storage unit B1 to the terminal T1 and the terminal T2. It includes switching elements SW1 and SW2 (first switching circuit) that switch states.
  • the switching elements SW1 and SW2 are an example of a first switching circuit and a second switching circuit, and constitute a half bridge in the example shown in FIG. 2.
  • first power storage unit B1 and switching element SW1 are connected in series, and switching element SW2 is connected in parallel with the series circuit of first power storage unit B1 and switching element SW1.
  • a connection point between switching element SW1 and switching element SW2 is connected to terminal T1, and a connection point between switching element SW2 and first power storage unit B1 is connected to terminal T2.
  • the terminal T1 is connected to the terminal T2 of the unit module EM on the higher potential side than the own module, and the terminal T2 is connected to the terminal T1 of the unit module EM on the lower potential side than the own module. Thereby, a plurality of unit modules EM are connected in series.
  • the terminal T1 of the unit module EM on the highest potential side in the upper arm 3H is connected to the power line WH, and the terminal T2 of the unit module EM on the lowest potential side in the upper arm 3H is connected to one end of the inductor L.
  • a terminal T1 of the unit module EM on the highest potential side in the lower arm 3L is connected to the other end of the inductor L, and a terminal T2 of the unit module EM on the lowest potential side in the lower arm 3L is connected to the power line WL.
  • switching elements SW1 and SW2 can be used as the switching elements SW1 and SW2, and for example, semiconductor switching elements such as transistors can be suitably used.
  • Switching elements SW1 and SW2 are turned on and off according to a control signal from control section 5.
  • the battery pack is not limited to a single battery, but may be a combination of a plurality of secondary batteries.
  • the power storage block BB of the DC voltage source 4 is different from the unit module EM in that a second power storage section B2 is used instead of the first power storage section B1, and a terminal T3 (third terminal) and a terminal are used instead of the terminals T1 and T2. The difference is that T4 (fourth terminal) is used.
  • power storage block BB is configured in the same manner as unit module EM, so a description thereof will be omitted.
  • Various secondary batteries can be suitably used as the second power storage unit B2, and it is not limited to a single battery, but a battery pack that is a combination of a plurality of secondary batteries may be used as the second power storage unit B2.
  • the first power storage unit B1 As the first power storage unit B1, a secondary battery with a larger current rating than that of the second power storage unit B2 is used, and as the second power storage unit B2, a secondary battery with a larger power storage capacity than that of the first power storage unit B1 is used. It will be done.
  • the first power storage unit B1 of the legs 2u, 2v, and 2w supplies power to the load with a voltage waveform converted to three-phase alternating current or the like, so it is necessary to follow load fluctuations and instantaneously flow a large current. Therefore, it is preferable that the first power storage unit B1 is a secondary battery with a high current rating. However, secondary batteries with both a large current rating and a large storage capacity are difficult to obtain or are expensive.
  • the first power storage unit B1 is a secondary battery with a high current rating and a small power storage capacity, it will be easy to obtain and reduce costs while ensuring followability to load fluctuations.
  • the second power storage unit B2 of the DC voltage source 4 since the DC voltage source 4 supplies power to the legs 2u, 2v, and 2w at approximately DC voltage, the second power storage unit B2 of the DC voltage source 4 only needs to output approximately average current; Unlike power storage unit B1, there is little need to instantaneously output a large current.
  • a secondary battery with a low current rating and a large storage capacity is easier to obtain and cheaper than a secondary battery with a large current rating and a large storage capacity.
  • the second power storage unit B2 is a secondary battery with a smaller current rating and a larger power storage capacity than the first power storage unit B1
  • the small power storage capacity of the first power storage unit B1 is determined by the second power storage unit B2. It becomes easy to ensure followability to load fluctuations by the first power storage unit B1 having a large current rating while supplementing with a large power storage capacity.
  • the first power storage unit B1 is not necessarily limited to a secondary battery as long as it can store charge.
  • the first power storage unit B1 may be configured with a capacitor such as an electric double layer capacitor.
  • the power storage capacity is smaller than when the first power storage unit B1 is configured with a secondary battery. If the storage capacity of the first power storage unit B1 is small, if the first power storage unit B1 momentarily discharges a large current, it is necessary to quickly transfer the charge from the DC voltage source 4 to the first power storage unit B1 for charging. As a result, the instantaneous value of the current flowing through the power lines WL and WH increases. As the instantaneous value of the current flowing through the power lines WL, WH increases, the power loss occurring in the power lines WL, WH increases.
  • the first power storage unit B1 is a secondary battery rather than a capacitor.
  • Terminal T3 is connected to terminal T4 of power storage block BB on the higher potential side than the own module, and terminal T4 is connected to terminal T3 of power storage block BB on the lower potential side than the own module.
  • the plurality of power storage blocks BB are connected in series.
  • Terminal T3 of power storage block BB on the highest potential side in DC voltage source 4 is connected to power line WH, and terminal T4 of power storage block BB on the lowest potential side in DC voltage source 4 is connected to power line WL.
  • the unit module EM and the power storage block BB indicated by the symbol A are in the connected state, and the unit module EM and the power storage block BB indicated by the symbol B are in the disconnected state.
  • the switching element SW1 is on and the switching element SW2 is off, and in the detached state, the switching element SW1 is off and the switching element SW2 is on.
  • the first power storage section B1 in the unit module EM in the joined state is connected in series in the upper arm 3H and the lower arm 3L, and the unit module EM in the detached state is short-circuited.
  • the voltage across the upper arm 3H and the lower arm 3L becomes the total voltage of the first power storage unit B1 in the connected state in the upper arm 3H and the lower arm 3L.
  • the second power storage units B2 in the power storage blocks BB in the joined state are connected in series, and the power storage blocks BB in the detached state are short-circuited.
  • the voltage output from power storage block BB between power lines WL and WH becomes the total voltage of second power storage unit B2 in the joining state in power storage block BB.
  • FIG. 3 is a conceptual circuit diagram showing an example of a unit module EM and a power storage block BB using full bridges as the first switching circuit and the second switching circuit.
  • the full-bridge unit module EM and power storage block BB shown in FIG. 3 further include switching elements SW3 and SW4 in addition to the half-bridge unit module EM and power storage block BB shown in FIG.
  • switching elements SW3 and SW4 switching elements similar to the switching elements SW1 and SW2 can be used.
  • a series circuit of switching elements SW3 and SW4 is connected in parallel to a series circuit of switching elements SW1 and SW2.
  • a connection point between switching elements SW1 and SW2 is connected to terminal T1 or terminal T3, and a connection point between switching elements SW3 and SW4 is connected to terminal T2 or terminal T4.
  • the switching elements SW1, SW2, SW3, and SW4 correspond to an example of a full bridge first switching circuit and second switching circuit.
  • the full-bridge unit module EM and power storage block BB shown in FIG. 3 can be in an inverted state as shown by C in addition to the joined state shown by symbol A and the detached state shown by symbol B.
  • first power storage unit B1 and second power storage unit B2 are connected with their polarities reversed.
  • switching elements SW1 and SW4 are on and switching elements SW2 and SW3 are off; in a detached state, switching elements SW1 and SW3 are off and switching elements SW2 and SW4 are on; in an inverted state, switching elements SW1 and SW4 are off. , switching elements SW2 and SW3 are turned on. Note that in the detached state, the switching elements SW1 and SW3 may be turned on and the switching elements SW2 and SW4 may be turned off.
  • control unit 5 controls the switching elements SW1 and SW2 to control the connection state including the joining state and the leaving state, or controlling the switching elements SW1 to SW4 to control the joining state, the leaving state, and the inverted state. Controlling the connection state including the connection state is simply referred to as controlling the connection state.
  • the voltage across the upper arm 3H and the lower arm 3L is the total voltage of the first power storage section B1 of the unit module EM in the connected state in the upper arm 3H and lower arm 3L. , the voltage obtained by subtracting the total voltage of the first power storage unit B1 of the unit module EM in the inverted state.
  • the voltage is obtained by subtracting the total voltage of the second power storage unit B2 of the power storage block BB in the inverted state from the total voltage of the unit B2.
  • the control unit 5 shown in FIG. 1 includes, for example, a CPU (Central Processing Unit) that executes predetermined logical operations, a RAM (Random Access Memory) that temporarily stores data, a nonvolatile storage device, and peripheral circuits thereof. etc., and operates by executing a predetermined program.
  • a CPU Central Processing Unit
  • RAM Random Access Memory
  • the control unit 5 converts the power obtained from the DC voltage source 4 by the legs 2u, 2v, and 2w by controlling the switching of the connection state by the switching elements SW1, SW2 (SW3, SW4) in each unit module EM. , or the first power storage unit B1 of the legs 2u, 2v, 2w is charged with regenerated power taken in from the outside through the external terminals Tu, Tv, Tw.
  • a known inverter control method can be used.
  • a control method for a modular multilevel converter may be used.
  • control unit 5 controls the switching of the connection state by the switching elements SW1, SW2 (SW3, SW4) in each power storage block BB and/or each unit module EM, so that the DC voltage source 4 and the legs 2u, 2v, Controls the movement of charges to and from 2w. Further, the control unit 5 controls the switching of the connection state between the legs 2u, 2v, and 2w by controlling the switching of the connection state by the switching elements SW1 and SW2 (SW3, SW4) in the unit module EM of each leg 2u, 2v, and 2w. Controls the movement of charges.
  • FIG. 4 is a flowchart showing an example of the operation related to output control of the power conversion device 1 shown in FIG. 1. First, output control when outputting power from the power conversion device 1 to the three-phase power loads connected to the external terminals Tu, Tv, and Tw will be described.
  • FIGS. 7 to 10 are explanatory diagrams for explaining the operation of the power conversion device 1 shown in FIG. 1.
  • the unit module EM and the power storage block BB use a half bridge, and the upper arm 3H and the lower arm 3L each include four unit modules EM.
  • the DC voltage source 4 includes eight power storage blocks BB, which is the same number as the unit modules EM of the leg 2. Further, the explanation will be made assuming that the voltages of each unit module EM and each power storage block BB are all the same.
  • the connection state of each unit module EM and each power storage block BB the joined state is described as ON, and the detached state is described as OFF.
  • the output voltage (voltage at both ends) of the legs 2u, 2v, 2w and the output voltage (voltage at both ends) of the DC voltage source 4 are as follows. equal to each other.
  • the open end voltages of the legs 2u, 2v, 2w and the DC voltage source 4 are the sum of the open end voltages of the unit modules EM or power storage blocks BB in the joined state, respectively.
  • the open end voltage of leg 2u is shown as VOu
  • the open end voltage of leg 2v is shown as VOv
  • the open end voltage of leg 2w is shown as VOw
  • the open end voltage of DC voltage source 4 is shown as VOps.
  • the open circuit voltages VOu, VOv, and VOw can be measured as follows. That is, the power converter 1 includes a voltage sensor that detects the voltage of each first power storage section B1, and by measuring the voltage of the first power storage section B1 of the unit module EM in the detached state with the voltage sensor, the power converter 1 detects the voltage of each first power storage section B1.
  • the open end voltage of power storage unit B1, that is, the open end voltage of each unit module EM can be measured.
  • the open end voltages VOu, VOv, and VOw are obtained by summing the open end voltages of the unit modules EM in the joined state for each leg in the legs 2u, 2v, and 2w.
  • the open circuit voltage VOps can be measured as follows. That is, the power conversion device 1 is equipped with a voltage sensor that detects the voltage of each second power storage unit B2, and by measuring the voltage of the second power storage unit B2 of the power storage block BB in the detached state with the voltage sensor, each second power storage unit B2 is detected. The open end voltage of power storage unit B2, that is, the open end voltage of each power storage block BB can be measured. The open end voltage VOps is obtained by summing the open end voltages of the power storage blocks BB in the connected state in the DC voltage source 4.
  • each first power storage unit B1 of legs 2u, 2v, and 2w is charged in advance.
  • the control unit 5 generates predetermined three-phase AC power in the legs 2u, 2v, and 2w by controlling the connection state of each unit module EM based on, for example, known modular multilevel conversion control, and generates predetermined three-phase AC power from the external It outputs to the three-phase power load connected to the terminals Tu, Tv, and Tw (step S1).
  • the number of unit modules EM in the joining state (ON) in legs 2u, 2v, and 2w is four each, and the voltage of each unit module EM is the same. Therefore, the open circuit voltages VOu, VOv, and VOw are equal to each other, and no charge transfer occurs between the legs 2u, 2v, and 2w in principle. Further, the number of power storage blocks BB in the ON state in the DC voltage source 4 is four, which is the same as the legs 2u, 2v, and 2w, and the open-circuit voltages VOu, VOv, and VOw are equal to the open-circuit voltage VOps. Therefore, in principle, no charge transfer occurs between the DC voltage source 4 and the leg 2.
  • step S1 the control unit 5 changes the ratio of the voltage of the upper arm 3H in the legs 2u, 2v, and 2w to the voltage of the lower arm 3L in the legs 2u, 2v, and 2w. Controls power conversion by legs 2u, 2v, and 2w.
  • the voltage ratio between upper arm 3H and lower arm 3L on leg 2u is 1:3
  • the voltage ratio between upper arm 3H and lower arm 3L on leg 2v is 2:2
  • the voltage ratio between upper arm 3H and lower arm 3L on leg 2w The voltage ratio is 3:1.
  • control unit 5 can vary the voltages output from the legs 2u, 2v, 2w to the external terminals Tu, Tv, Tw while keeping the open end voltages Vou, VOv, VOw constant. Further, the control unit 5 controls the external It is possible to output three-phase AC power whose phase is shifted by 120 degrees to the terminals Tu, Tv, and Tw.
  • the control unit 5 acquires the amount of charge Qo output from the external terminals Tu, Tv, and Tw of the legs 2u, 2v, and 2w to the outside (step S2). For example, when the power conversion device 1 is mounted on an electric vehicle and the external terminals Tu, Tv, and Tw are connected to the motor of the electric vehicle, the control unit 5 transmits data representing the amount of charge Qo to the motor from the electric vehicle side. The amount of electricity Ah or Wh that has flowed may be acquired. Further, the control unit 5 may calculate the amount of electric charge Qo by acquiring the value of the current flowing through the motor from an electric vehicle or the like and integrating the values.
  • the power conversion device 1 includes a current sensor that detects the current flowing between the legs 2u, 2v, 2w and the external terminals Tu, Tv, Tw, and the control unit 5 controls the current value detected by the current sensor.
  • the amount of charge Qo may be calculated by integrating .
  • control unit 5 controls the connection state of each power storage block BB and/or unit module EM so as to relatively increase the open end voltage VOps of the DC voltage source 4. , 2v, and 2w, and charge each first power storage unit B1 (step S3).
  • the open circuit voltage VOps is increased by increasing the number of power storage blocks BB in the joining state in the DC voltage source 4 from four to five.
  • the open circuit voltage VOps becomes relatively higher than the open circuit voltages VOu, VOv, and VOw, and current flows from the DC voltage source 4 to the legs 2u, 2v, and 2w, and the transferred charges cause each first storage Part B1 is charged.
  • control unit 5 only needs to be able to increase the open-circuit voltage VOps of the DC voltage source 4 relative to the open-circuit voltages VOu, VOv, and VOw, for example, depending on the joining state in the legs 2u, 2v, and 2w.
  • the open circuit voltages VOu, VOv, VOw may be lowered by reducing the number of unit modules EM, or the increase in the open circuit voltage VOps and the decrease in the open circuit voltages VOu, VOv, VOw may be combined.
  • control unit 5 acquires the amount of charge Qm transferred from the DC voltage source 4 to the legs 2u, 2v, and 2w (step S4).
  • the control unit 5 can acquire the amount of charge Qm by integrating the current values detected by the current sensor 7 and flowing from the DC voltage source 4 to the legs 2u, 2v, and 2w.
  • control unit 5 compares the amount of charge Qm and the amount of charge Qo (step S5). If the charge amount Qm is less than the charge amount Qo (NO in step S5), steps S1 to S4 are repeated to continue moving the charge from the DC voltage source 4 to the legs 2u, 2v, and 2w. On the other hand, if the amount of charge Qm reaches the amount of charge Qo (YES in step S5), the control unit 5 controls the connection state of each power storage block BB and/or unit module EM, and increases the open end voltage VOps and the open end voltage Vou. , VOv, and VOw are made substantially equal to stop the transfer of charges from the DC voltage source 4 to the legs 2u, 2v, and 2w (step S6), and the process returns to step S1.
  • step S5 the amount of charge Qo and the amount of charge Qm only need to be approximately the same, and do not need to be exactly the same.
  • the amount of charge Qm may be between 0.8 ⁇ Qo and 1.2 ⁇ Qo.
  • steps S1 to S6 the control unit 5 moves the amount of charge Qm, which is approximately the same as the amount of charge Qo outputted to the outside from the legs 2u, 2v, and 2w, from the DC voltage source 4 to the legs 2u, 2v, and 2w. I can do it.
  • the amount of discharge of each first power storage unit B1 can be replenished, and it becomes possible to continue the three-phase power output operation by the legs 2u, 2v, and 2w. Therefore, according to steps S1 to S6, it becomes easy to appropriately charge the first power storage section B1 of each unit module EM.
  • steps S2, S4, and S5 an example has been shown in which charges are transferred from the DC voltage source 4 to the leg 2 based on the amount of charge Qo outputted to the outside from the leg 2.
  • 2v, 2w may be used to transfer the charge from the DC voltage source 4 to the leg 2.
  • control unit 5 calculates total values SVu, SVv, and SVw of open-circuit voltages of first power storage unit B1 included in legs 2u, 2v, and 2w, respectively. Then, when any one of the total values SVu, SVv, and SVw is lower than the preset first reference voltage Vref1, the control unit 5 relatively adjusts the open-circuit voltage VOps of the DC voltage source 4, as in step S3.
  • each power storage block BB and/or unit module EM By controlling the connection state of each power storage block BB and/or unit module EM so as to increase the electric charge, the electric charge is moved from the DC voltage source 4 to the first power storage part B1 in the legs 2u, 2v, 2w, and each first Power storage unit B1 may be charged.
  • the total values SVu, SVv, and SVw correspond to the open circuit voltages Vou, VOv, and VOw when all unit modules EM in each leg are in the joining state.
  • Power conversion device 1 includes a voltage sensor that detects the voltage of each first power storage unit B1, and control unit 5 obtains the open end voltage of each first power storage unit B1 detected by the voltage sensor, thereby calculating the total The values SVu, SVv, and SVw can be calculated.
  • the first reference voltage Vref1 the value of the total values SVu, SVv, and SVw at which it is necessary to charge the legs 2u, 2v, and 2w can be appropriately set in advance.
  • the total values SVu, SVv, and SVw decrease as the amount of charge in the legs 2u, 2v, and 2w decreases. Therefore, when the legs 2u, 2v, 2w are discharged and any one of the total values SVu, SVv, SVw becomes lower than the first reference voltage Vref1, the DC voltage source 4 supplies the first storage battery in the legs 2u, 2v, 2w. By moving the charge to portion B1, it becomes easy to appropriately charge first power storage portion B1 of each unit module EM.
  • FIG. 5 is a flowchart showing an example of an operation related to regeneration control of the power converter shown in FIG.
  • the control unit 5 controls the connection state of each unit module EM of the legs 2u, 2v, 2w.
  • the regenerative current obtained at the external terminals Tu, Tv, and Tw is charged to each first power storage unit B1 of the legs 2u, 2v, and 2w (step S11).
  • control unit 5 acquires the amount of charge Qi charged in the legs 2u, 2v, and 2w (step S12). Similarly to step S2, the control unit 5 may obtain the charge amount Qi based on data obtained from an external source such as an electric vehicle, and by integrating current values detected by a current sensor (not shown), The amount of charge Qi may also be calculated.
  • control unit 5 controls the connection state of each power storage block BB and/or unit module EM so as to relatively reduce the open end voltage VOps of the DC voltage source 4.
  • the charge is transferred from the first power storage unit B1 in the DC voltage source 4 to the DC voltage source 4, and each second power storage unit B2 of the DC voltage source 4 is charged (step S13).
  • the open circuit voltage VOps is lowered by reducing the number of power storage blocks BB in the joining state in the DC voltage source 4 from four to three.
  • the open-circuit voltage VOps becomes relatively lower than the open-circuit voltages VOu, VOv, and VOw, and current flows from the legs 2u, 2v, and 2w to the DC voltage source 4, and the transferred charges cause each second storage Part B2 is charged.
  • control unit 5 only needs to be able to lower the open-circuit voltage VOps of the DC voltage source 4 relative to the open-circuit voltages VOu, VOv, and VOw;
  • the open circuit voltages VOu, VOv, VOw may be increased by increasing the number of unit modules EM, or the decrease in the open circuit voltage VOps and the increase in the open circuit voltages VOu, VOv, VOw may be combined.
  • control unit 5 acquires the amount of charge Qn transferred from the legs 2u, 2v, and 2w to the DC voltage source 4 (step S14).
  • the control unit 5 can acquire the amount of charge Qn by integrating the current values detected by the current sensor 7 and flowing from the legs 2u, 2v, and 2w to the DC voltage source 4.
  • control unit 5 compares the amount of charge Qn and the amount of charge Qi (step S15). If the charge amount Qn is less than the charge amount Qi (NO in step S15), steps S11 to S14 are repeated to continue moving the charges from the legs 2u, 2v, and 2w to the DC voltage source 4. On the other hand, if the amount of charge Qn reaches the amount of charge Qi (YES in step S15), the control unit 5 controls the connection state of each power storage block BB and/or unit module EM, and increases the open end voltage VOps and the open end voltage VOut. , VOv, and VOw are made substantially equal to stop the transfer of charges from the legs 2u, 2v, and 2w to the DC voltage source 4 (step S16), and the process returns to step S11.
  • step S15 the amount of charge Qi and the amount of charge Qn only need to be approximately the same, and do not need to be exactly the same.
  • the amount of charge Qn may be 0.8 ⁇ Qi to 1.2 ⁇ Qi.
  • the control unit 5 moves the amount of charge Qn, which is substantially the same as the amount of charge Qi regenerated from the outside to the legs 2u, 2v, and 2w, from the legs 2u, 2v, and 2w to the DC voltage source 4. I can do it. As a result, the amount of charge regenerated from the outside to legs 2u, 2v, 2w and charged in each first power storage unit B1 can be transferred to each second power storage unit B2 of DC voltage source 4, so that each It becomes possible to receive regenerated power from the outside while preventing power storage unit B1 from being overcharged.
  • steps S12, S14, and S15 an example has been shown in which charges are transferred from the leg 2 to the DC voltage source 4 based on the amount of charge Qi charged to the leg 2 from the outside.
  • 2v, 2w may be used to transfer the charge from the leg 2 to the DC voltage source 4.
  • control unit 5 calculates total values SVu, SVv, and SVw of the open end voltages of first power storage unit B1 included in legs 2u, 2v, and 2w, respectively. Then, when any one of the total values SVu, SVv, and SVw exceeds the preset second reference voltage Vref2, the control unit 5 relatively adjusts the open-circuit voltage VOps of the DC voltage source 4, as in step S13. By controlling the connection state of each power storage block BB and/or unit module EM so as to lower the electric charge, the charge is moved from the first power storage section B1 in the legs 2u, 2v, 2w to the DC voltage source 4, and each second Power storage unit B2 may be charged.
  • the value of the total value SVu, SVv, SVw that will cause it to be necessary to discharge the legs 2u, 2v, 2w when the legs 2u, 2v, 2w are charged with regenerative current should be set appropriately in advance. I can do it.
  • the total values SVu, SVv, and SVw increase as the amount of charge in the legs 2u, 2v, and 2w increases. Therefore, when the legs 2u, 2v, 2w are charged and any one of the total values SVu, SVv, SVw exceeds the second reference voltage Vref2, the legs 2u, 2v, 2w are charged to the second storage unit of the DC voltage source 4. By moving the charge to B2, it becomes easy to appropriately recover regenerated power from the outside.
  • balance control for balancing the amount of charge between the legs 2u, 2v, and 2w will be described.
  • the amount of charge by the first power storage unit B1 between the legs 2u, 2v, and 2w may become unbalanced. If the charges between the legs 2u, 2v, and 2w become unbalanced, a voltage difference will occur between the phases, which is inconvenient. Therefore, by performing the balance control described below, the imbalance in the amount of charge between the legs 2u, 2v, and 2w is reduced.
  • FIG. 6 is a flowchart illustrating an example of an operation related to balance control of the power conversion device illustrated in FIG. 1.
  • control unit 5 calculates and compares total values SVu, SVv, and SVw of open-circuit voltages of first power storage unit B1 included in legs 2u, 2v, and 2w, respectively (step S21).
  • control unit 5 controls the connection state of each unit module EM of the legs 2u, 2v, and 2w so as to relatively increase the open end voltage VO of the leg 2 with the largest total value SV (step S22 ).
  • FIG. 10 is an explanatory diagram showing a case where the total value SVu of leg 2u is the maximum and the total value SVw of leg 2w is the minimum.
  • the control unit 5 relatively increases the open end voltage Vou by increasing the number of unit modules EM in the joined state of the leg 2u, as shown in FIG. .
  • charge is transferred from leg 2u, which has the largest total value SVu and therefore the highest amount of charge, to the other legs 2v and 2w, reducing the imbalance in the amount of charge between legs 2u, 2v, and 2w. .
  • the control unit 5 may further reduce the number of unit modules EM in the joining state of the leg 2w with the smallest total value SV, as shown in FIG. 10. As a result, the amount of charge transferred to leg 2w is greater than the amount of charge transferred to leg 2v, so that the effect of reducing the imbalance in the amount of charge between legs 2u, 2v, and 2w is further increased.
  • control unit 5 only needs to relatively increase the open-circuit voltage VO of leg 2 with the largest total value SV, and is limited to the example in which the open-circuit voltage VO of leg 2 with the largest total value SV itself is increased. do not have.
  • the control unit 5 may relatively increase the open end voltage VO of the leg 2 having the maximum total value SV by lowering the open end voltage VO of the legs other than the leg 2 having the maximum total value SV.
  • the power conversion device 1 is not limited to the example including the three legs 2u, 2v, and 2w.
  • the power converter 1 may be a single-phase power converter having one leg, or may be a power converter having two, four or more legs.

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Abstract

[Problem] To provide a power converter that makes it simple to suitably charge a power storage unit of a unit module. [Solution] A power converter 1 comprises a leg 2, a DC voltage source 4, and a control unit 5. Individual unit modules EM of an upper arm 3H and a lower arm 3L include terminals T1, T2, first power storage unit B1, and first switching circuits SW1, SW2 that switch between connection states including a connected state and a disconnected state. Individual power storage blocks BB of the DC voltage source 4 include terminals T3, T4, a second power storage unit B2, and second switching circuits SW1, SW2 that switch between connection states including a connected status and a disconnected state. The control unit 5 outputs a prescribed power to the leg 2 by controlling switching between the connection states, and controls movement of a charge between the DC voltage source 4 and the leg 2 by controlling switching between the connection states.

Description

電力変換装置power converter
　本発明は、電力変換を行う電力変換装置に関する。 The present invention relates to a power conversion device that performs power conversion.
　近年、直流－交流変換を行うインバータとして、単位モジュールを複数直列接続したモジュールを組み合わせる、モジュラーマルチレベル変換器（MMC：Modular Multilevel Converter）が用いられている（例えば、特許文献１参照。）。モジュラーマルチレベル変換器は、単位モジュールに含まれるキャパシタの端子電圧を加算することによって、任意の出力電圧を出力可能とされている。モジュラーマルチレベル変換器を用いたインバータは、電気自動車やハイブリッド車等の電動車両に、好適に用いられる。 In recent years, modular multilevel converters (MMC), which combine modules in which multiple unit modules are connected in series, have been used as inverters that perform DC-AC conversion (for example, see Patent Document 1). A modular multilevel converter is capable of outputting an arbitrary output voltage by adding the terminal voltages of capacitors included in a unit module. An inverter using a modular multilevel converter is suitably used in electric vehicles such as electric cars and hybrid cars.
特開２０１５－０１２７６９号公報Japanese Patent Application Publication No. 2015-012769
　ところで、単位モジュールのキャパシタは、放電すると端子電圧が低下する。そのため、モジュラーマルチレベル変換器を継続動作させるためには、単位モジュールのキャパシタを適切に充電する必要がある。 By the way, when the capacitor of a unit module is discharged, the terminal voltage decreases. Therefore, in order to continue operating the modular multilevel converter, it is necessary to appropriately charge the capacitors of the unit modules.
　本発明の目的は、単位モジュールの蓄電部を適切に充電することが容易な電力変換装置を提供することである。 An object of the present invention is to provide a power conversion device that makes it easy to appropriately charge the power storage unit of a unit module.
　本発明に係る電力変換装置は、上アームとインダクタと下アームとが、この順に直列接続されたレグと、複数の蓄電ブロックが直列接続された直列回路を含むと共に、前記レグと並列に接続された直流電圧源と、制御部とを備え、前記上アーム及び前記下アームのそれぞれは、複数の単位モジュールが直列接続された直列回路を含み、前記各単位モジュールは、第一及び第二端子と、電荷を蓄える第一蓄電部と、前記第一及び第二端子へ前記第一蓄電部を接続する加入状態と前記第一及び第二端子間を短絡する離脱状態とを含む接続状態を切り換える第一切換回路とを含み、前記各蓄電ブロックは、第三及び第四端子と、電荷を蓄える第二蓄電部と、前記第三及び第四端子へ前記第二蓄電部を接続する加入状態と前記第三及び第四端子間を短絡する離脱状態とを含む接続状態を切り換える第二切換回路とを含み、前記制御部は、前記各第一切換回路による接続状態の切り替えを制御することによって、前記レグに所定の電力を出力させ、前記各第一切換回路及び／又は前記各第二切換回路による接続状態の切り替えを制御することによって、前記直流電圧源と前記レグとの間での電荷の移動を制御する。 The power conversion device according to the present invention includes an upper arm, an inductor, and a lower arm, which include a leg connected in series in this order, a series circuit in which a plurality of power storage blocks are connected in series, and are connected in parallel with the leg. each of the upper arm and the lower arm includes a series circuit in which a plurality of unit modules are connected in series, and each of the unit modules has a first terminal and a second terminal. , a first power storage unit that stores charge; and a first power storage unit that switches connection states including a connected state in which the first power storage unit is connected to the first and second terminals and a disconnected state in which the first and second terminals are short-circuited. each of the electricity storage blocks includes a third and fourth terminal, a second electricity storage unit that stores charge, a connected state that connects the second electricity storage unit to the third and fourth terminals; a second switching circuit that switches connection states including a disconnection state that short-circuits between the third and fourth terminals, and the control unit controls switching of the connection state by each of the first switching circuits. Transfer of electric charge between the DC voltage source and the leg by causing the leg to output a predetermined power and controlling switching of the connection state by each of the first switching circuit and/or the second switching circuit. control.
　この構成によれば、加入状態とされた単位モジュールの第一蓄電部は直列接続され、離脱状態とされた単位モジュールの第一蓄電部は直列接続されない。従って、第一切換回路によって、加入状態の単位モジュールの数を増減することによって、レグの電圧を制御することが可能となる。同様に、加入状態とされた蓄電ブロックの第二蓄電部は直列接続され、離脱状態とされた蓄電ブロックの第二蓄電部は直列接続されない。従って、第一切換回路によって、加入状態の単位モジュールの数を増減することによって、レグの電圧を制御することが可能となる。第二切換回路によって、加入状態の蓄電ブロックの数を増減することによって、直流電圧源の電圧を制御することが可能となる。そして、レグと直流電圧源とは並列に接続されているので、直流電圧源の電圧をレグの電圧より相対的に高くすれば直流電圧源からレグへ電荷を移動させてレグの単位モジュールを充電することができる。従って、単位モジュールの蓄電部を適切に充電することが容易となる。 According to this configuration, the first power storage units of the unit modules that are in the joined state are connected in series, and the first power storage units of the unit modules that are in the detached state are not connected in series. Therefore, the first switching circuit makes it possible to control the voltage of the leg by increasing or decreasing the number of unit modules in the joined state. Similarly, the second power storage units of the power storage blocks that are in the joining state are connected in series, and the second power storage units of the power storage blocks that are in the detached state are not connected in series. Therefore, the first switching circuit makes it possible to control the voltage of the leg by increasing or decreasing the number of unit modules in the joined state. The second switching circuit makes it possible to control the voltage of the DC voltage source by increasing or decreasing the number of power storage blocks in the joined state. Since the leg and the DC voltage source are connected in parallel, if the voltage of the DC voltage source is made relatively higher than the voltage of the leg, charge will be transferred from the DC voltage source to the leg and the unit module of the leg will be charged. can do. Therefore, it becomes easy to appropriately charge the power storage section of the unit module.
　また、前記各第一蓄電部及び前記各第二蓄電部は、二次電池であり、前記各第二蓄電部は、前記各第一蓄電部よりも蓄電容量が大きいことが好ましい。 Furthermore, it is preferable that each of the first power storage unit and each of the second power storage unit is a secondary battery, and each of the second power storage units has a larger power storage capacity than each of the first power storage unit.
　この構成によれば、外部へ電力を出力するレグ内の第一蓄電部は、第二蓄電部よりも蓄電容量が小さくてよいので、蓄電容量よりもレグによる電力変換に適した性能の二次電池を第一蓄電部として用いることが容易となる。 According to this configuration, the first power storage unit in the leg that outputs power to the outside may have a smaller power storage capacity than the second power storage unit. It becomes easy to use the battery as the first power storage unit.
　また、前記各第一蓄電部は、前記各第二蓄電部よりも電流定格が大きいことが好ましい。 Further, it is preferable that each of the first power storage units has a higher current rating than each of the second power storage units.
　この構成によれば、負荷変動に応じてレグから供給可能な瞬時電力を増大させつつ、直流電圧源の第二蓄電部からレグへ平均電力に相当する電荷を移動させ、レグ内の第一蓄電部を充電することが容易となる。 According to this configuration, while increasing the instantaneous power that can be supplied from the leg according to load fluctuations, the electric charge corresponding to the average power is transferred from the second power storage unit of the DC voltage source to the leg, and the first power storage unit in the leg It becomes easy to charge the parts.
　また、前記制御部は、前記直流電圧源の電圧を相対的に上昇させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記直流電圧源から前記レグへ電荷を移動させることが好ましい。 Further, the control unit controls switching of the connection state by each of the first switching circuits and/or each of the second switching circuits so as to relatively increase the voltage of the DC voltage source. Preferably, charge is transferred from a voltage source to said leg.
　この構成によれば、制御部は、加入状態の蓄電ブロック数を増加させることによって直流電圧源の電圧を上昇させることができ、加入状態の単位モジュール数を減少させることによってレグの電圧を低下させることができる。従って、制御部は、各第一切換回路及び／又は各第二切換回路による接続状態の切り替えを制御して直流電圧源の電圧を相対的に上昇させることによって、直流電圧源からレグへ電荷を移動させることができる。 According to this configuration, the control unit can increase the voltage of the DC voltage source by increasing the number of power storage blocks in the subscribed state, and reduce the voltage of the leg by decreasing the number of unit modules in the subscribed state. be able to. Therefore, the control unit controls switching of the connection state by each first switching circuit and/or each second switching circuit to relatively increase the voltage of the DC voltage source, thereby transferring electric charge from the DC voltage source to the leg. It can be moved.
　また、前記制御部は、前記レグから外部へ出力された電荷量と略同一の電荷量を、前記直流電圧源から前記レグへ移動させるように、前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することが好ましい。 Further, the control unit controls each of the first switching circuits and/or each of the first switching circuits and/or each of the first switching circuits so that substantially the same amount of charge as the amount of charge outputted from the leg to the outside is transferred from the DC voltage source to the leg. Preferably, switching of the connection state is controlled by two switching circuits.
　この構成によれば、レグから外部へ出力された電荷量と略同一の電荷量を、直流電圧源からレグへ移動させることができるので、レグによる外部への電力出力を継続することが可能となる。 According to this configuration, it is possible to transfer approximately the same amount of charge from the DC voltage source to the leg as the amount of charge output from the leg to the outside, so it is possible to continue outputting power to the outside by the leg. Become.
　また、前記制御部は、前記レグに含まれる前記第一蓄電部の開放端電圧の合計が、予め設定された第一基準電圧を下回った場合、前記直流電圧源の出力電圧を相対的に上昇させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記直流電圧源から前記レグへ電荷を移動させることが好ましい。 In addition, when the total open end voltage of the first power storage unit included in the leg is lower than a preset first reference voltage, the control unit relatively increases the output voltage of the DC voltage source. It is preferable that charges be transferred from the DC voltage source to the leg by controlling switching of the connection state by each of the first switching circuits and/or each of the second switching circuits so as to move the charge from the DC voltage source to the leg.
　第一蓄電部が放電すると開放端電圧が低下する。従って、レグに含まれる第一蓄電部の開放端電圧の合計が第一基準電圧を下回った場合、直流電圧源の出力電圧を相対的に上昇させて直流電圧源からレグへ電荷を移動させることによって、レグによる外部への電力出力を継続することが可能となる。 When the first power storage unit discharges, the open circuit voltage decreases. Therefore, when the total open end voltage of the first power storage unit included in the leg is lower than the first reference voltage, the output voltage of the DC voltage source is relatively increased to move the charge from the DC voltage source to the leg. This allows the leg to continue outputting power to the outside.
　また、前記制御部は、前記直流電圧源の電圧を相対的に低下させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記レグから前記直流電圧源へ電荷を移動させることが好ましい。 Further, the control unit controls switching of the connection state by each of the first switching circuits and/or each of the second switching circuits so as to relatively reduce the voltage of the DC voltage source. Preferably, charge is transferred from the DC voltage source to the DC voltage source.
　この構成によれば、制御部は、加入状態の蓄電ブロック数を減少させることによって直流電圧源の電圧を低下させることができ、加入状態の単位モジュール数を増加させることによってレグの電圧を上昇させることができる。従って、制御部は、各第一切換回路及び／又は各第二切換回路による接続状態の切り替えを制御して直流電圧源の電圧を相対的に低下させることによって、レグから直流電圧源へ電荷を移動させることができる。 According to this configuration, the control unit can lower the voltage of the DC voltage source by decreasing the number of power storage blocks in the subscribed state, and increase the voltage of the leg by increasing the number of unit modules in the subscribed state. be able to. Therefore, the control unit controls switching of the connection state by each first switching circuit and/or each second switching circuit to relatively lower the voltage of the DC voltage source, thereby transferring electric charge from the leg to the DC voltage source. It can be moved.
　また、前記制御部は、外部から前記レグへ入力された電荷量と略同一の電荷量を、前記レグから前記直流電圧源へ移動させるように、前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することが好ましい。 Further, the control unit controls each of the first switching circuits and/or each of the first switching circuits and/or each of the first switching circuits so as to transfer substantially the same amount of charge from the leg to the DC voltage source as the amount of charge input from the outside to the leg. Preferably, switching of the connection state is controlled by two switching circuits.
　例えばモータの回生電力等、外部からレグへ電力が入力される場合がある。この構成によれば、外部からレグへ入力された電荷量と略同一の電荷量を、レグから直流電圧源へ移動させることができるので、外部からの電力の受け入れを継続することが可能となる。 For example, power may be input to the leg from the outside, such as regenerated power from a motor. According to this configuration, it is possible to transfer approximately the same amount of charge from the leg to the DC voltage source as the amount of charge input from the outside to the leg, making it possible to continue receiving power from the outside. .
　また、前記制御部は、前記レグに含まれる前記第一蓄電部の開放端電圧の合計が、予め設定された第二基準電圧を上回った場合、前記直流電圧源の出力電圧を相対的に低下させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記レグから前記直流電圧源へ電荷を移動させることが好ましい。 In addition, when the total open end voltage of the first power storage unit included in the leg exceeds a preset second reference voltage, the control unit relatively reduces the output voltage of the DC voltage source. It is preferable that charges be transferred from the leg to the DC voltage source by controlling switching of the connection state by each of the first switching circuit and/or each of the second switching circuit so as to cause the charge to move from the leg to the DC voltage source.
　第一蓄電部の充電量が増大すると開放端電圧が上昇する。従って、レグに含まれる第一蓄電部の開放端電圧の合計が第二基準電圧を上回った場合、直流電圧源の出力電圧を相対的に低下させてレグから直流電圧源へ電荷を移動させることによって、レグによる外部からの電力受け入れを継続することが可能となる。 As the amount of charge in the first power storage unit increases, the open circuit voltage increases. Therefore, when the total open end voltage of the first power storage unit included in the leg exceeds the second reference voltage, the output voltage of the DC voltage source is relatively lowered to move the charge from the leg to the DC voltage source. This allows the leg to continue receiving power from the outside.
　また、前記制御部は、さらに、前記レグ内における前記上アームの電圧と、前記レグ内における前記下アームの電圧との比率を変化させることによって、前記レグによる電力変換を制御することが好ましい。 Further, it is preferable that the control unit further controls power conversion by the leg by changing a ratio between the voltage of the upper arm in the leg and the voltage of the lower arm in the leg.
　レグ内における上アームの電圧と、レグ内における下アームの電圧との比率は、レグの両端電圧とは独立して変化させることが可能である。従って、この構成によれば、レグの両端電圧とは独立してレグの出力電圧を変化させ、電力変換を行うことが可能となる。その結果、レグによる電力変換動作と、直流電圧源とレグの間での電荷の移動とを並行して行うことが可能となる。 The ratio between the voltage of the upper arm within the leg and the voltage of the lower arm within the leg can be changed independently of the voltage across the leg. Therefore, according to this configuration, it is possible to change the output voltage of the leg independently of the voltage across the leg and perform power conversion. As a result, it becomes possible to perform the power conversion operation by the leg and the movement of charge between the DC voltage source and the leg in parallel.
　また、前記各第一切換回路は、ハーフブリッジ又はフルブリッジのブリッジ回路であり、前記各第二切替回路は、ハーフブリッジ又はフルブリッジのブリッジ回路であることが好ましい。 Further, each of the first switching circuits is preferably a half-bridge or full-bridge bridge circuit, and each of the second switching circuits is preferably a half-bridge or full-bridge bridge circuit.
　ハーフブリッジの第一切換回路は、単位モジュールの接続状態を、加入状態と離脱状態とに切り替えることができる。フルブリッジの第一切換回路は、単位モジュールの接続状態を、加入状態及び離脱状態に加えて、加入状態とは逆極性で第一及び第二端子へ第一蓄電部を接続する反転状態に切り替えることができる。ハーフブリッジの第二切換回路は、蓄電ブロックの接続状態を、加入状態と離脱状態とに切り替えることができる。フルブリッジの第二切換回路は、蓄電ブロックの接続状態を、加入状態及び離脱状態に加えて、加入状態とは逆極性で第三及び第四端子へ第二蓄電部を接続する反転状態に切り替えることができる。 The first switching circuit of the half-bridge can switch the connection state of the unit module between an joining state and a detached state. The full-bridge first switching circuit switches the connection state of the unit module to a joining state and a disconnecting state, as well as an inverted state in which the first power storage unit is connected to the first and second terminals with polarity opposite to the joining state. be able to. The second switching circuit of the half-bridge can switch the connection state of the power storage block between an joining state and a detached state. The second switching circuit of the full bridge switches the connection state of the power storage block, in addition to the joining state and the detached state, to an inverted state in which the second power storage unit is connected to the third and fourth terminals with polarity opposite to the joining state. be able to.
　また、前記レグを複数備え、前記複数のレグは並列接続され、前記制御部は、さらに、前記各レグに含まれる前記第一蓄電部の開放端電圧の合計値を比較し、相対的に前記合計値が大きいレグの電圧を相対的に上昇させるように前記各レグの第一切換回路による前記接続状態の切り替えを制御することによって、前記相対的に前記合計値が大きいレグから、前記相対的に前記合計値が小さいレグへ電荷を移動させることが好ましい。 Further, the plurality of legs are provided, and the plurality of legs are connected in parallel, and the control unit further compares the total value of the open end voltage of the first power storage unit included in each of the legs, and relatively By controlling the switching of the connection state by the first switching circuit of each leg so as to relatively increase the voltage of the leg having a relatively large total value, the voltage of the leg having a relatively large total value increases. It is preferable to move the charge to the leg having the smaller total value.
　この構成によれば、レグが複数並列接続されているので、複数のレグによる、より複雑な電力変換を行うことが可能となる。 According to this configuration, since a plurality of legs are connected in parallel, it is possible to perform more complicated power conversion using a plurality of legs.
　また、前記レグを三つ備え、前記三つのレグは、互いに並列接続されて三相インバータを構成することが好ましい。 Further, it is preferable that the three legs are provided, and the three legs are connected in parallel to each other to form a three-phase inverter.
　この構成によれば、三相交流電力を出力することが可能となる。 According to this configuration, it is possible to output three-phase AC power.
　このような構成の電力変換装置は、単位モジュールの蓄電部を適切に充電することが容易である。 In the power conversion device having such a configuration, it is easy to appropriately charge the power storage unit of the unit module.
本発明の一実施形態に係る電力変換装置の構成の一例を示すブロック図である。1 is a block diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention. 図１に示す単位モジュールＥＭ及び蓄電ブロックＢＢの構成の一例を示す概念的な回路図である。2 is a conceptual circuit diagram showing an example of the configuration of a unit module EM and a power storage block BB shown in FIG. 1. FIG. 第一切換回路、第二切換回路としてフルブリッジを用いた単位モジュールＥＭ、蓄電ブロックＢＢの一例を示す概念的な回路図である。It is a conceptual circuit diagram showing an example of a unit module EM and a power storage block BB using full bridges as a first switching circuit and a second switching circuit. 図１に示す電力変換装置の出力制御に係る動作の一例を示すフローチャートである。2 is a flowchart showing an example of an operation related to output control of the power conversion device shown in FIG. 1. FIG. 図１に示す電力変換装置の回生制御に係る動作の一例を示すフローチャートである。2 is a flowchart showing an example of an operation related to regeneration control of the power converter shown in FIG. 1. FIG. 図１に示す電力変換装置のバランス制御に係る動作の一例を示すフローチャートである。2 is a flowchart showing an example of an operation related to balance control of the power conversion device shown in FIG. 1. FIG. 図１に示す電力変換装置の動作を説明するための説明図である。2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1. FIG. 図１に示す電力変換装置の動作を説明するための説明図である。2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1. FIG. 図１に示す電力変換装置の動作を説明するための説明図である。2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1. FIG. 図１に示す電力変換装置の動作を説明するための説明図である。2 is an explanatory diagram for explaining the operation of the power conversion device shown in FIG. 1. FIG.
　以下、本発明に係る実施形態を図面に基づいて説明する。なお、各図において同一の符号を付した構成は、同一の構成であることを示し、その説明を省略する。図１は、本発明の一実施形態に係る電力変換装置の構成の一例を示すブロック図である。 Hereinafter, embodiments according to the present invention will be described based on the drawings. It should be noted that structures given the same reference numerals in each figure indicate the same structure, and the explanation thereof will be omitted. FIG. 1 is a block diagram showing an example of the configuration of a power conversion device according to an embodiment of the present invention.
　図１に示す電力変換装置１は、大略的に、レグ２ｕ，２ｖ，２ｗと、直流電圧源４と、キャパシタＣと、制御部５と、電流センサ７と、外部端子Ｔｕ，Ｔｖ，Ｔｗとを備えている。レグ２ｕ，２ｖ，２ｗが並列接続されて、三相インバータ６が構成されている。三相インバータ６、キャパシタＣ、及び直流電圧源４は、高電位側の電力線ＷＨと、低電位側の電力線ＷＬによって、並列接続されている。 The power conversion device 1 shown in FIG. 1 roughly includes legs 2u, 2v, and 2w, a DC voltage source 4, a capacitor C, a control unit 5, a current sensor 7, and external terminals Tu, Tv, and Tw. It is equipped with The legs 2u, 2v, and 2w are connected in parallel to form a three-phase inverter 6. The three-phase inverter 6, the capacitor C, and the DC voltage source 4 are connected in parallel by a power line WH on the high potential side and a power line WL on the low potential side.
　電流センサ７は、直流電圧源４と三相インバータ６との間を流れる電流を検出し、その電流値を制御部５へ送信する。キャパシタＣは、平滑や電圧安定化等を行う。なお、電力変換装置１は、必ずしもキャパシタＣを備えていなくてもよく、電流センサ７を備えていなくてもよい。 The current sensor 7 detects the current flowing between the DC voltage source 4 and the three-phase inverter 6, and transmits the current value to the control unit 5. Capacitor C performs smoothing, voltage stabilization, etc. Note that the power conversion device 1 does not necessarily need to include the capacitor C, and does not necessarily need to include the current sensor 7.
　レグ２ｕは、上アーム３ＨとインダクタＬと下アーム３Ｌとが、この順に直列接続されて構成されている。レグ２ｖ，２ｗは、レグ２ｕと同様に構成されているのでその説明を省略する。以下、レグ２ｕ，２ｖ，２ｗを総称してレグ２と称する。 The leg 2u is configured by an upper arm 3H, an inductor L, and a lower arm 3L connected in series in this order. Legs 2v and 2w are configured similarly to leg 2u, so a description thereof will be omitted. Hereinafter, legs 2u, 2v, and 2w will be collectively referred to as leg 2.
　レグ２ｕのインダクタＬの中点が外部端子Ｔｕと接続され、レグ２ｖのインダクタＬの中点が外部端子Ｔｖと接続され、レグ２ｗのインダクタＬの中点が外部端子Ｔｗと接続されている。これにより、外部端子Ｔｕ，Ｔｖ，Ｔｗが、電力変換装置１の三相電力出力端子、又は三相回生電流入力端子として機能する。外部端子Ｔｕ，Ｔｖ，Ｔｗには、例えば三相モータ等の、種々の三相電力負荷を接続することができ、電力変換装置１を電動車両に搭載してもよい。 The midpoint of inductor L of leg 2u is connected to external terminal Tu, the midpoint of inductor L of leg 2v is connected to external terminal Tv, and the midpoint of inductor L of leg 2w is connected to external terminal Tw. Thereby, the external terminals Tu, Tv, and Tw function as three-phase power output terminals or three-phase regenerative current input terminals of the power conversion device 1. Various three-phase power loads, such as a three-phase motor, can be connected to the external terminals Tu, Tv, and Tw, and the power conversion device 1 may be mounted on an electric vehicle.
　インダクタＬは、例えばセンタータップ付リアクトルであってもよく、二つのインダクタを直列接続し、その接続点を外部端子Ｔｕ，Ｔｖ，Ｔｗに接続したものであってもよい。 The inductor L may be, for example, a reactor with a center tap, or may be one in which two inductors are connected in series and their connection points are connected to external terminals Tu, Tv, and Tw.
　上アーム３Ｈ及び下アーム３Ｌのそれぞれは、複数の単位モジュールＥＭが直列接続された直列回路を含んでいる。図１に示す例では、上アーム３Ｈ及び下アーム３Ｌは、複数の単位モジュールＥＭが直列接続された直列回路のみから構成される例を示しているが、上アーム３Ｈ及び下アーム３Ｌは、単位モジュールＥＭの直列回路を含んでいればよく、単位モジュールＥＭの直列回路以外のものを含んでいてもよい。 Each of the upper arm 3H and the lower arm 3L includes a series circuit in which a plurality of unit modules EM are connected in series. In the example shown in FIG. 1, the upper arm 3H and the lower arm 3L are composed of only a series circuit in which a plurality of unit modules EM are connected in series, but the upper arm 3H and the lower arm 3L are It is only necessary to include the series circuit of the module EM, and it may include something other than the series circuit of the unit module EM.
　直流電圧源４は、複数の蓄電ブロックＢＢが直列接続された直列回路を含んでいる。図１に示す例では、直流電圧源４は、複数の蓄電ブロックＢＢが直列接続された直列回路のみから構成される例を示しているが、直流電圧源４は、蓄電ブロックＢＢの直列回路を含んでいればよく、蓄電ブロックＢＢの直列回路以外のものを含んでいてもよい。 The DC voltage source 4 includes a series circuit in which a plurality of power storage blocks BB are connected in series. In the example shown in FIG. 1, the DC voltage source 4 is configured only from a series circuit in which a plurality of power storage blocks BB are connected in series. It is sufficient that the circuit includes a circuit other than the series circuit of the power storage block BB.
　図２は、図１に示す単位モジュールＥＭ及び蓄電ブロックＢＢの構成の一例を示す概念的な回路図である。図２では、蓄電ブロックＢＢに係る構成の符号を括弧書きで示している。 FIG. 2 is a conceptual circuit diagram showing an example of the configuration of the unit module EM and power storage block BB shown in FIG. 1. In FIG. 2, the symbols of the configurations related to the power storage block BB are shown in parentheses.
　レグ２の単位モジュールＥＭは、端子Ｔ１（第一端子）、端子Ｔ２（第二端子）、電荷を蓄える第一蓄電部Ｂ１、端子Ｔ１及び端子Ｔ２への第一蓄電部Ｂ１の電気的な接続状態を切り換えるスイッチング素子ＳＷ１，ＳＷ２（第一切換回路）とを含んでいる。スイッチング素子ＳＷ１，ＳＷ２は、第一切換回路及び第二切換回路の一例であり、図２に示す例では、ハーフブリッジを構成している。 The unit module EM of leg 2 includes a terminal T1 (first terminal), a terminal T2 (second terminal), a first power storage unit B1 that stores electric charge, and an electrical connection of the first power storage unit B1 to the terminal T1 and the terminal T2. It includes switching elements SW1 and SW2 (first switching circuit) that switch states. The switching elements SW1 and SW2 are an example of a first switching circuit and a second switching circuit, and constitute a half bridge in the example shown in FIG. 2.
　具体的には、第一蓄電部Ｂ１とスイッチング素子ＳＷ１とが直列接続され、第一蓄電部Ｂ１とスイッチング素子ＳＷ１の直列回路と並列にスイッチング素子ＳＷ２が接続されている。スイッチング素子ＳＷ１とスイッチング素子ＳＷ２の接続点が端子Ｔ１に接続され、スイッチング素子ＳＷ２と第一蓄電部Ｂ１の接続点が端子Ｔ２に接続されている。 Specifically, first power storage unit B1 and switching element SW1 are connected in series, and switching element SW2 is connected in parallel with the series circuit of first power storage unit B1 and switching element SW1. A connection point between switching element SW1 and switching element SW2 is connected to terminal T1, and a connection point between switching element SW2 and first power storage unit B1 is connected to terminal T2.
　端子Ｔ１は、自モジュールよりも高電位側の単位モジュールＥＭの端子Ｔ２に接続され、端子Ｔ２は、自モジュールよりも低電位側の単位モジュールＥＭの端子Ｔ１に接続される。これにより、複数の単位モジュールＥＭが直列接続されている。 The terminal T1 is connected to the terminal T2 of the unit module EM on the higher potential side than the own module, and the terminal T2 is connected to the terminal T1 of the unit module EM on the lower potential side than the own module. Thereby, a plurality of unit modules EM are connected in series.
　上アーム３Ｈ内で最も高電位側の単位モジュールＥＭの端子Ｔ１は電力線ＷＨに接続され、上アーム３Ｈ内で最も低電位側の単位モジュールＥＭの端子Ｔ２はインダクタＬの一端に接続される。下アーム３Ｌ内で最も高電位側の単位モジュールＥＭの端子Ｔ１はインダクタＬの他端に接続され、下アーム３Ｌ内で最も低電位側の単位モジュールＥＭの端子Ｔ２は電力線ＷＬに接続される。 The terminal T1 of the unit module EM on the highest potential side in the upper arm 3H is connected to the power line WH, and the terminal T2 of the unit module EM on the lowest potential side in the upper arm 3H is connected to one end of the inductor L. A terminal T1 of the unit module EM on the highest potential side in the lower arm 3L is connected to the other end of the inductor L, and a terminal T2 of the unit module EM on the lowest potential side in the lower arm 3L is connected to the power line WL.
　スイッチング素子ＳＷ１，ＳＷ２としては、種々のスイッチング素子を用いることができ、例えばトランジスタ等の半導体スイッチング素子を好適に用いることができる。スイッチング素子ＳＷ１，ＳＷ２は、制御部５からの制御信号に応じてオン、オフする。 Various switching elements can be used as the switching elements SW1 and SW2, and for example, semiconductor switching elements such as transistors can be suitably used. Switching elements SW1 and SW2 are turned on and off according to a control signal from control section 5.
　第一蓄電部Ｂ１としては、種々の二次電池を好適に用いることができ、単電池に限られず、複数の二次電池を組み合わせた組電池を第一蓄電部Ｂ１として用いてもよい。 Various secondary batteries can be suitably used as the first power storage unit B1, and the battery pack is not limited to a single battery, but may be a combination of a plurality of secondary batteries.
　直流電圧源４の蓄電ブロックＢＢは、単位モジュールＥＭとは、第一蓄電部Ｂ１の代わりに第二蓄電部Ｂ２を用いる点、端子Ｔ１及び端子Ｔ２の代わりに端子Ｔ３（第三端子）及び端子Ｔ４（第四端子）を用いる点が異なる。その他の点では蓄電ブロックＢＢは、単位モジュールＥＭと同様に構成されているのでその説明を省略する。 The power storage block BB of the DC voltage source 4 is different from the unit module EM in that a second power storage section B2 is used instead of the first power storage section B1, and a terminal T3 (third terminal) and a terminal are used instead of the terminals T1 and T2. The difference is that T4 (fourth terminal) is used. In other respects, power storage block BB is configured in the same manner as unit module EM, so a description thereof will be omitted.
　第二蓄電部Ｂ２としては、種々の二次電池を好適に用いることができ、単電池に限られず、複数の二次電池を組み合わせた組電池を第二蓄電部Ｂ２として用いてもよい。 Various secondary batteries can be suitably used as the second power storage unit B2, and it is not limited to a single battery, but a battery pack that is a combination of a plurality of secondary batteries may be used as the second power storage unit B2.
　第一蓄電部Ｂ１としては、第二蓄電部Ｂ２よりも電流定格が大きい二次電池が用いられ、第二蓄電部Ｂ２としては、第一蓄電部Ｂ１よりも蓄電容量が大きい二次電池が用いられる。 As the first power storage unit B1, a secondary battery with a larger current rating than that of the second power storage unit B2 is used, and as the second power storage unit B2, a secondary battery with a larger power storage capacity than that of the first power storage unit B1 is used. It will be done.
　レグ２ｕ，２ｖ，２ｗの第一蓄電部Ｂ１は、三相交流等に変換された電圧波形で負荷へ電力を供給するので、負荷変動に追従して瞬間的に大電流を流す必要がある。そのため、第一蓄電部Ｂ１は、電流定格が大きい二次電池であることが好ましい。しかしながら、電流定格と、蓄電容量とが共に大きな二次電池は、入手が困難であったり、高価であったりする。 The first power storage unit B1 of the legs 2u, 2v, and 2w supplies power to the load with a voltage waveform converted to three-phase alternating current or the like, so it is necessary to follow load fluctuations and instantaneously flow a large current. Therefore, it is preferable that the first power storage unit B1 is a secondary battery with a high current rating. However, secondary batteries with both a large current rating and a large storage capacity are difficult to obtain or are expensive.
　そこで、第一蓄電部Ｂ１を、電流定格が大きく、蓄電容量が小さな二次電池とすれば、負荷変動への追従性を確保しつつ、入手性やコスト低減が容易となる。 Therefore, if the first power storage unit B1 is a secondary battery with a high current rating and a small power storage capacity, it will be easy to obtain and reduce costs while ensuring followability to load fluctuations.
　一方、直流電圧源４は、略直流電圧でレグ２ｕ，２ｖ，２ｗへ電力を供給するので、直流電圧源４の第二蓄電部Ｂ２は、略平均的な電流を出力すればよく、第一蓄電部Ｂ１のように、瞬間的に大電流を出力する必要性は低い。電流定格が小さく蓄電容量が大きい二次電池は、電流定格が大きく蓄電容量が大きい二次電池よりも、入手し易く、安価である。 On the other hand, since the DC voltage source 4 supplies power to the legs 2u, 2v, and 2w at approximately DC voltage, the second power storage unit B2 of the DC voltage source 4 only needs to output approximately average current; Unlike power storage unit B1, there is little need to instantaneously output a large current. A secondary battery with a low current rating and a large storage capacity is easier to obtain and cheaper than a secondary battery with a large current rating and a large storage capacity.
　そこで、第二蓄電部Ｂ２を、第一蓄電部Ｂ１よりも、電流定格が小さく蓄電容量が大きい二次電池とすれば、第一蓄電部Ｂ１の蓄電容量の小ささを、第二蓄電部Ｂ２の大きな蓄電容量で補いつつ、電流定格が大きい第一蓄電部Ｂ１によって、負荷変動への追従性を確保することが容易となる。 Therefore, if the second power storage unit B2 is a secondary battery with a smaller current rating and a larger power storage capacity than the first power storage unit B1, then the small power storage capacity of the first power storage unit B1 is determined by the second power storage unit B2. It becomes easy to ensure followability to load fluctuations by the first power storage unit B1 having a large current rating while supplementing with a large power storage capacity.
　なお、第一蓄電部Ｂ１は、電荷を蓄えることができればよく、必ずしも二次電池に限られない。例えば、第一蓄電部Ｂ１を、電気二重層コンデンサ等のキャパシタで構成してもよい。 Note that the first power storage unit B1 is not necessarily limited to a secondary battery as long as it can store charge. For example, the first power storage unit B1 may be configured with a capacitor such as an electric double layer capacitor.
　しかしながら、第一蓄電部Ｂ１をキャパシタで構成した場合、第一蓄電部Ｂ１を二次電池で構成した場合よりも蓄電容量が小さくなる。第一蓄電部Ｂ１の蓄電容量が小さいと、第一蓄電部Ｂ１が瞬間的に大電流を放電した場合、速やかに直流電圧源４から第一蓄電部Ｂ１へ電荷を移動させて充電する必要が生じるため、電力線ＷＬ，ＷＨを流れる電流の瞬時値が大きくなる。電力線ＷＬ，ＷＨを流れる電流の瞬時値が大きくなると、電力線ＷＬ，ＷＨで生じる電力損失が大きくなる。 However, when the first power storage unit B1 is configured with a capacitor, the power storage capacity is smaller than when the first power storage unit B1 is configured with a secondary battery. If the storage capacity of the first power storage unit B1 is small, if the first power storage unit B1 momentarily discharges a large current, it is necessary to quickly transfer the charge from the DC voltage source 4 to the first power storage unit B1 for charging. As a result, the instantaneous value of the current flowing through the power lines WL and WH increases. As the instantaneous value of the current flowing through the power lines WL, WH increases, the power loss occurring in the power lines WL, WH increases.
　そこで、第一蓄電部Ｂ１を、キャパシタよりも蓄電容量を大きくすることが容易な二次電池とすることによって、第一蓄電部Ｂ１が瞬間的に大電流を放電した場合であっても、第一蓄電部Ｂ１の蓄電量で賄うことが容易となる。その結果、直流電圧源４から電力線ＷＬ，ＷＨを介してレグ２ｕ，２ｖ，２ｗへ供給される電流の瞬時値が低減され、電力線ＷＬ，ＷＨで生じる電力損失を低減することが容易となる。従って、第一蓄電部Ｂ１は、キャパシタよりも二次電池であることがより好ましい。 Therefore, by using a secondary battery whose storage capacity is easier to increase than a capacitor as the first power storage unit B1, even if the first power storage unit B1 momentarily discharges a large current, the This can easily be covered by the amount of electricity stored in one electricity storage unit B1. As a result, the instantaneous value of the current supplied from the DC voltage source 4 to the legs 2u, 2v, 2w via the power lines WL, WH is reduced, making it easier to reduce power loss occurring in the power lines WL, WH. Therefore, it is more preferable that the first power storage unit B1 is a secondary battery rather than a capacitor.
　端子Ｔ３は、自ブロックよりも高電位側の蓄電ブロックＢＢの端子Ｔ４に接続され、端子Ｔ４は、自モジュールよりも低電位側の蓄電ブロックＢＢの端子Ｔ３に接続される。これにより、複数の蓄電ブロックＢＢが直列接続されている。 Terminal T3 is connected to terminal T4 of power storage block BB on the higher potential side than the own module, and terminal T4 is connected to terminal T3 of power storage block BB on the lower potential side than the own module. Thereby, the plurality of power storage blocks BB are connected in series.
　直流電圧源４内で最も高電位側の蓄電ブロックＢＢの端子Ｔ３は電力線ＷＨに接続され、直流電圧源４内で最も低電位側の蓄電ブロックＢＢの端子Ｔ４は電力線ＷＬに接続される。 Terminal T3 of power storage block BB on the highest potential side in DC voltage source 4 is connected to power line WH, and terminal T4 of power storage block BB on the lowest potential side in DC voltage source 4 is connected to power line WL.
　符号Ａで示す単位モジュールＥＭ及び蓄電ブロックＢＢは、接続状態が加入状態とされており、符号Ｂで示す単位モジュールＥＭ及び蓄電ブロックＢＢは、接続状態が離脱状態とされている。加入状態ではスイッチング素子ＳＷ１がオン、スイッチング素子ＳＷ２がオフし、離脱状態ではスイッチング素子ＳＷ１がオフ、スイッチング素子ＳＷ２がオンする。 The unit module EM and the power storage block BB indicated by the symbol A are in the connected state, and the unit module EM and the power storage block BB indicated by the symbol B are in the disconnected state. In the join state, the switching element SW1 is on and the switching element SW2 is off, and in the detached state, the switching element SW1 is off and the switching element SW2 is on.
　加入状態の単位モジュールＥＭにおける第一蓄電部Ｂ１は、上アーム３Ｈ及び下アーム３Ｌにおいて直列接続され、離脱状態の単位モジュールＥＭは短絡される。これにより、上アーム３Ｈ、下アーム３Ｌにおける両端電圧は、上アーム３Ｈ、下アーム３Ｌにおける加入状態の第一蓄電部Ｂ１の合計電圧となる。 The first power storage section B1 in the unit module EM in the joined state is connected in series in the upper arm 3H and the lower arm 3L, and the unit module EM in the detached state is short-circuited. As a result, the voltage across the upper arm 3H and the lower arm 3L becomes the total voltage of the first power storage unit B1 in the connected state in the upper arm 3H and the lower arm 3L.
　同様に、加入状態の蓄電ブロックＢＢにおける第二蓄電部Ｂ２は直列接続され、離脱状態の蓄電ブロックＢＢは短絡される。これにより、蓄電ブロックＢＢから電力線ＷＬ，ＷＨ間へ出力される電圧は、蓄電ブロックＢＢにおける加入状態の第二蓄電部Ｂ２の合計電圧となる。 Similarly, the second power storage units B2 in the power storage blocks BB in the joined state are connected in series, and the power storage blocks BB in the detached state are short-circuited. Thereby, the voltage output from power storage block BB between power lines WL and WH becomes the total voltage of second power storage unit B2 in the joining state in power storage block BB.
　なお、単位モジュールＥＭは第一切換回路としてフルブリッジを用いてもよく、蓄電ブロックＢＢは第二切換回路としてフルブリッジを用いてもよい。図３は、第一切換回路、第二切換回路としてフルブリッジを用いた単位モジュールＥＭ、蓄電ブロックＢＢの一例を示す概念的な回路図である。 Note that the unit module EM may use a full bridge as the first switching circuit, and the power storage block BB may use a full bridge as the second switching circuit. FIG. 3 is a conceptual circuit diagram showing an example of a unit module EM and a power storage block BB using full bridges as the first switching circuit and the second switching circuit.
　図３に示すフルブリッジの単位モジュールＥＭ、蓄電ブロックＢＢは、図２に示すハーフブリッジの単位モジュールＥＭ、蓄電ブロックＢＢに加えて、さらにスイッチング素子ＳＷ３，ＳＷ４を備える。スイッチング素子ＳＷ３，ＳＷ４としては、スイッチング素子ＳＷ１，ＳＷ２と同様のスイッチング素子を用いることができる。 The full-bridge unit module EM and power storage block BB shown in FIG. 3 further include switching elements SW3 and SW4 in addition to the half-bridge unit module EM and power storage block BB shown in FIG. As the switching elements SW3 and SW4, switching elements similar to the switching elements SW1 and SW2 can be used.
　具体的には、スイッチング素子ＳＷ３，ＳＷ４の直列回路がスイッチング素子ＳＷ１，ＳＷ２の直列回路と並列に接続されている。スイッチング素子ＳＷ１，ＳＷ２の接続点が端子Ｔ１又は端子Ｔ３に接続され、スイッチング素子ＳＷ３，ＳＷ４の接続点が端子Ｔ２又は端子Ｔ４に接続されている。スイッチング素子ＳＷ１，ＳＷ２，ＳＷ３，ＳＷ４は、フルブリッジの第一切換回路、第二切換回路の一例に相当する。 Specifically, a series circuit of switching elements SW3 and SW4 is connected in parallel to a series circuit of switching elements SW1 and SW2. A connection point between switching elements SW1 and SW2 is connected to terminal T1 or terminal T3, and a connection point between switching elements SW3 and SW4 is connected to terminal T2 or terminal T4. The switching elements SW1, SW2, SW3, and SW4 correspond to an example of a full bridge first switching circuit and second switching circuit.
　図３に示すフルブリッジの単位モジュールＥＭ、蓄電ブロックＢＢは、符号Ａで示す加入状態、符号Ｂで示す離脱状態に加えて、符号Ｃで示す反転状態とすることができる。反転状態の単位モジュールＥＭ、蓄電ブロックＢＢでは、第一蓄電部Ｂ１、第二蓄電部Ｂ２が、極性を反転させて接続される。 The full-bridge unit module EM and power storage block BB shown in FIG. 3 can be in an inverted state as shown by C in addition to the joined state shown by symbol A and the detached state shown by symbol B. In unit module EM and power storage block BB in the inverted state, first power storage unit B1 and second power storage unit B2 are connected with their polarities reversed.
　加入状態ではスイッチング素子ＳＷ１，ＳＷ４がオン、スイッチング素子ＳＷ２，ＳＷ３がオフし、離脱状態ではスイッチング素子ＳＷ１，ＳＷ３がオフ、スイッチング素子ＳＷ２，ＳＷ４がオンし、反転状態ではスイッチング素子ＳＷ１，ＳＷ４がオフ、スイッチング素子ＳＷ２，ＳＷ３がオンする。なお、離脱状態ではスイッチング素子ＳＷ１，ＳＷ３をオン、スイッチング素子ＳＷ２，ＳＷ４をオフさせてもよい。 In the joining state, switching elements SW1 and SW4 are on and switching elements SW2 and SW3 are off; in a detached state, switching elements SW1 and SW3 are off and switching elements SW2 and SW4 are on; in an inverted state, switching elements SW1 and SW4 are off. , switching elements SW2 and SW3 are turned on. Note that in the detached state, the switching elements SW1 and SW3 may be turned on and the switching elements SW2 and SW4 may be turned off.
　以下、制御部５が、スイッチング素子ＳＷ１，ＳＷ２を制御して加入状態及び離脱状態を含む接続状態を制御すること、又はスイッチング素子ＳＷ１～ＳＷ４を制御して加入状態、離脱状態、及び反転状態を含む接続状態を制御することを、単に、接続状態を制御する、と記載する。 Hereinafter, the control unit 5 controls the switching elements SW1 and SW2 to control the connection state including the joining state and the leaving state, or controlling the switching elements SW1 to SW4 to control the joining state, the leaving state, and the inverted state. Controlling the connection state including the connection state is simply referred to as controlling the connection state.
　図３に示すフルブリッジの単位モジュールＥＭを用いた場合、上アーム３Ｈ、下アーム３Ｌにおける両端電圧は、上アーム３Ｈ、下アーム３Ｌにおける加入状態の単位モジュールＥＭの第一蓄電部Ｂ１の合計電圧から、反転状態の単位モジュールＥＭの第一蓄電部Ｂ１の合計電圧を減算した電圧となる。 When the full-bridge unit module EM shown in FIG. 3 is used, the voltage across the upper arm 3H and the lower arm 3L is the total voltage of the first power storage section B1 of the unit module EM in the connected state in the upper arm 3H and lower arm 3L. , the voltage obtained by subtracting the total voltage of the first power storage unit B1 of the unit module EM in the inverted state.
　同様に、図３に示すフルブリッジの蓄電ブロックＢＢを用いた場合、直流電圧源４から電力線ＷＬ，ＷＨ間へ出力される電圧は、直流電圧源４における加入状態の蓄電ブロックＢＢの第二蓄電部Ｂ２の合計電圧から、反転状態の蓄電ブロックＢＢの第二蓄電部Ｂ２の合計電圧を減算した電圧となる。 Similarly, when using the full bridge power storage block BB shown in FIG. The voltage is obtained by subtracting the total voltage of the second power storage unit B2 of the power storage block BB in the inverted state from the total voltage of the unit B2.
　図１に示す制御部５は、例えば、所定の論理演算を実行するＣＰＵ(Central Processing Unit)、データを一時的に記憶するＲＡＭ(Random Access Memory)、不揮発性の記憶装置、及びこれらの周辺回路等を備えて構成され、所定のプログラムを実行することによって動作する。 The control unit 5 shown in FIG. 1 includes, for example, a CPU (Central Processing Unit) that executes predetermined logical operations, a RAM (Random Access Memory) that temporarily stores data, a nonvolatile storage device, and peripheral circuits thereof. etc., and operates by executing a predetermined program.
　制御部５は、各単位モジュールＥＭにおけるスイッチング素子ＳＷ１，ＳＷ２（ＳＷ３，ＳＷ４）による接続状態の切り替えを制御することによって、直流電圧源４から得られた電力をレグ２ｕ，２ｖ，２ｗで変換させ、あるいは外部から外部端子Ｔｕ，Ｔｖ，Ｔｗで取り込まれた回生電力をレグ２ｕ，２ｖ，２ｗの第一蓄電部Ｂ１に充電する。 The control unit 5 converts the power obtained from the DC voltage source 4 by the legs 2u, 2v, and 2w by controlling the switching of the connection state by the switching elements SW1, SW2 (SW3, SW4) in each unit module EM. , or the first power storage unit B1 of the legs 2u, 2v, 2w is charged with regenerated power taken in from the outside through the external terminals Tu, Tv, Tw.
　三相インバータ６、すなわちレグ２ｕ，２ｖ，２ｗによって、電圧や電圧波形等を変換又は回生する制御方法としては、公知のインバータ制御方法を用いることができ、例えばモジュラーマルチレベル変換器に関する制御方法を用いることができる。 As a control method for converting or regenerating voltage, voltage waveforms, etc. by the three-phase inverter 6, that is, the legs 2u, 2v, and 2w, a known inverter control method can be used. For example, a control method for a modular multilevel converter may be used. Can be used.
　また、制御部５は、各蓄電ブロックＢＢ及び／又は各単位モジュールＥＭにおけるスイッチング素子ＳＷ１，ＳＷ２（ＳＷ３，ＳＷ４）による接続状態の切り替えを制御することによって、直流電圧源４とレグ２ｕ，２ｖ，２ｗとの間での電荷の移動を制御する。また、制御部５は、レグ２ｕ，２ｖ，２ｗ毎の単位モジュールＥＭにおけるスイッチング素子ＳＷ１，ＳＷ２（ＳＷ３，ＳＷ４）による接続状態の切り替えを制御することによって、レグ２ｕ，２ｖ，２ｗ相互間での電荷の移動を制御する。 In addition, the control unit 5 controls the switching of the connection state by the switching elements SW1, SW2 (SW3, SW4) in each power storage block BB and/or each unit module EM, so that the DC voltage source 4 and the legs 2u, 2v, Controls the movement of charges to and from 2w. Further, the control unit 5 controls the switching of the connection state between the legs 2u, 2v, and 2w by controlling the switching of the connection state by the switching elements SW1 and SW2 (SW3, SW4) in the unit module EM of each leg 2u, 2v, and 2w. Controls the movement of charges.
　図４は、図１に示す電力変換装置１の出力制御に係る動作の一例を示すフローチャートである。まず、電力変換装置１から、外部端子Ｔｕ，Ｔｖ，Ｔｗに接続された三相電力負荷へ電力を出力する際の出力制御について説明する。 FIG. 4 is a flowchart showing an example of the operation related to output control of the power conversion device 1 shown in FIG. 1. First, output control when outputting power from the power conversion device 1 to the three-phase power loads connected to the external terminals Tu, Tv, and Tw will be described.
　図７～図１０は、図１に示す電力変換装置１の動作を説明するための説明図である。図７～図１０では、説明を容易にするため、以下の仮定条件を設定している。すなわち、単位モジュールＥＭ及び蓄電ブロックＢＢはハーフブリッジを用いるものとし、上アーム３Ｈ及び下アーム３Ｌは、それぞれ単位モジュールＥＭを四個ずつ備えるものとする。また、直流電圧源４は、レグ２の単位モジュールＥＭの数と同じ八個の蓄電ブロックＢＢを備えるものとする。また、各単位モジュールＥＭ及び各蓄電ブロックＢＢの電圧は、すべて同一として説明する。さらに、各単位モジュールＥＭ及び各蓄電ブロックＢＢの接続状態について、加入状態をＯＮ、離脱状態をＯＦＦと記載している。 7 to 10 are explanatory diagrams for explaining the operation of the power conversion device 1 shown in FIG. 1. In FIGS. 7 to 10, the following assumptions are set for ease of explanation. That is, it is assumed that the unit module EM and the power storage block BB use a half bridge, and the upper arm 3H and the lower arm 3L each include four unit modules EM. Further, it is assumed that the DC voltage source 4 includes eight power storage blocks BB, which is the same number as the unit modules EM of the leg 2. Further, the explanation will be made assuming that the voltages of each unit module EM and each power storage block BB are all the same. Furthermore, regarding the connection state of each unit module EM and each power storage block BB, the joined state is described as ON, and the detached state is described as OFF.
　なお、以上の仮定条件は、説明の都合上設定したものであり、電力変換装置１は、この仮定条件に限定されるものではない。 Note that the above assumed conditions are set for convenience of explanation, and the power conversion device 1 is not limited to these assumed conditions.
　レグ２ｕ，２ｖ，２ｗと、直流電圧源４とは並列接続されているので、レグ２ｕ，２ｖ，２ｗの出力電圧（両端電圧）と、直流電圧源４の出力電圧（両端電圧）とは、互いに等しい。しかしながら、レグ２ｕ，２ｖ，２ｗ及び直流電圧源４の開放端電圧は、それぞれ、加入状態の単位モジュールＥＭ又は蓄電ブロックＢＢの開放端電圧の合計となる。 Since the legs 2u, 2v, 2w and the DC voltage source 4 are connected in parallel, the output voltage (voltage at both ends) of the legs 2u, 2v, 2w and the output voltage (voltage at both ends) of the DC voltage source 4 are as follows. equal to each other. However, the open end voltages of the legs 2u, 2v, 2w and the DC voltage source 4 are the sum of the open end voltages of the unit modules EM or power storage blocks BB in the joined state, respectively.
　図７～図１０では、レグ２ｕの開放端電圧をＶＯｕ、レグ２ｖの開放端電圧をＶＯｖ、レグ２ｗの開放端電圧をＶＯｗ、直流電圧源４の開放端電圧をＶＯｐｓとして示している。 In FIGS. 7 to 10, the open end voltage of leg 2u is shown as VOu, the open end voltage of leg 2v is shown as VOv, the open end voltage of leg 2w is shown as VOw, and the open end voltage of DC voltage source 4 is shown as VOps.
　開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗは、以下のようにして測定することができる。すなわち、電力変換装置１が各第一蓄電部Ｂ１の電圧を検出する電圧センサを備え、離脱状態にした単位モジュールＥＭの第一蓄電部Ｂ１の電圧を電圧センサで測定することによって、各第一蓄電部Ｂ１の開放端電圧、すなわち各単位モジュールＥＭの開放端電圧を測定することができる。開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗは、レグ２ｕ，２ｖ，２ｗにおける、レグ毎の加入状態の単位モジュールＥＭの開放端電圧を合計することによって得られる。 The open circuit voltages VOu, VOv, and VOw can be measured as follows. That is, the power converter 1 includes a voltage sensor that detects the voltage of each first power storage section B1, and by measuring the voltage of the first power storage section B1 of the unit module EM in the detached state with the voltage sensor, the power converter 1 detects the voltage of each first power storage section B1. The open end voltage of power storage unit B1, that is, the open end voltage of each unit module EM can be measured. The open end voltages VOu, VOv, and VOw are obtained by summing the open end voltages of the unit modules EM in the joined state for each leg in the legs 2u, 2v, and 2w.
　開放端電圧ＶＯｐｓは、以下のようにして測定することができる。すなわち、電力変換装置１が各第二蓄電部Ｂ２の電圧を検出する電圧センサを備え、離脱状態にした蓄電ブロックＢＢの第二蓄電部Ｂ２の電圧を電圧センサで測定することによって、各第二蓄電部Ｂ２の開放端電圧、すなわち各蓄電ブロックＢＢの開放端電圧を測定することができる。開放端電圧をＶＯｐｓは、直流電圧源４における加入状態の蓄電ブロックＢＢの開放端電圧を合計することによって得られる。 The open circuit voltage VOps can be measured as follows. That is, the power conversion device 1 is equipped with a voltage sensor that detects the voltage of each second power storage unit B2, and by measuring the voltage of the second power storage unit B2 of the power storage block BB in the detached state with the voltage sensor, each second power storage unit B2 is detected. The open end voltage of power storage unit B2, that is, the open end voltage of each power storage block BB can be measured. The open end voltage VOps is obtained by summing the open end voltages of the power storage blocks BB in the connected state in the DC voltage source 4.
　まず、レグ２ｕ，２ｖ，２ｗの各第一蓄電部Ｂ１は、予め充電されている。この状態で、制御部５は、例えば公知のモジュラーマルチレベル変換制御に基づき各単位モジュールＥＭの接続状態を制御することによって、レグ２ｕ，２ｖ，２ｗで所定の三相交流電力を生成し、外部端子Ｔｕ，Ｔｖ，Ｔｗに接続された三相電力負荷へ出力する（ステップＳ１）。 First, each first power storage unit B1 of legs 2u, 2v, and 2w is charged in advance. In this state, the control unit 5 generates predetermined three-phase AC power in the legs 2u, 2v, and 2w by controlling the connection state of each unit module EM based on, for example, known modular multilevel conversion control, and generates predetermined three-phase AC power from the external It outputs to the three-phase power load connected to the terminals Tu, Tv, and Tw (step S1).
　図７では、レグ２ｕ，２ｖ，２ｗにおける加入状態（ＯＮ）の単位モジュールＥＭの数は、それぞれ四個であり、各単位モジュールＥＭの電圧は同一である。従って、開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗは互いに等しく、レグ２ｕ，２ｖ，２ｗ相互間では電荷の移動は原則生じない。また、直流電圧源４における加入状態（ＯＮ）の蓄電ブロックＢＢの数は、レグ２ｕ，２ｖ，２ｗと同じ四個であり、開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗと開放端電圧ＶＯｐｓとは等しい。従って、直流電圧源４とレグ２との間でも、電荷の移動は原則生じない。 In FIG. 7, the number of unit modules EM in the joining state (ON) in legs 2u, 2v, and 2w is four each, and the voltage of each unit module EM is the same. Therefore, the open circuit voltages VOu, VOv, and VOw are equal to each other, and no charge transfer occurs between the legs 2u, 2v, and 2w in principle. Further, the number of power storage blocks BB in the ON state in the DC voltage source 4 is four, which is the same as the legs 2u, 2v, and 2w, and the open-circuit voltages VOu, VOv, and VOw are equal to the open-circuit voltage VOps. Therefore, in principle, no charge transfer occurs between the DC voltage source 4 and the leg 2.
　この状態で、ステップＳ１において、制御部５は、レグ２ｕ，２ｖ，２ｗ内における上アーム３Ｈの電圧と、レグ２ｕ，２ｖ，２ｗ内における下アーム３Ｌの電圧との比率を変化させることによって、レグ２ｕ，２ｖ，２ｗによる電力変換を制御する。図７では、レグ２ｕにおける上アーム３Ｈと下アーム３Ｌの電圧比率は１：３、レグ２ｖにおける上アーム３Ｈと下アーム３Ｌの電圧比率は２：２、レグ２ｗにおける上アーム３Ｈと下アーム３Ｌの電圧比率は３：１となっている。 In this state, in step S1, the control unit 5 changes the ratio of the voltage of the upper arm 3H in the legs 2u, 2v, and 2w to the voltage of the lower arm 3L in the legs 2u, 2v, and 2w. Controls power conversion by legs 2u, 2v, and 2w. In FIG. 7, the voltage ratio between upper arm 3H and lower arm 3L on leg 2u is 1:3, the voltage ratio between upper arm 3H and lower arm 3L on leg 2v is 2:2, and the voltage ratio between upper arm 3H and lower arm 3L on leg 2w. The voltage ratio is 3:1.
　このように、制御部５は、開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗが一定のまま、レグ２ｕ，２ｖ，２ｗから外部端子Ｔｕ，Ｔｖ，Ｔｗへ出力される電圧を互いに異ならせることができる。さらに制御部５は、時間の経過に応じてレグ２ｕ，２ｖ，２ｗ内における上アーム３Ｈの電圧と、レグ２ｕ，２ｖ，２ｗ内における下アーム３Ｌの電圧との比率を変化させることによって、外部端子Ｔｕ，Ｔｖ，Ｔｗへ、１２０度ずつ位相がずれた三相交流電力を出力させることができる。 In this way, the control unit 5 can vary the voltages output from the legs 2u, 2v, 2w to the external terminals Tu, Tv, Tw while keeping the open end voltages Vou, VOv, VOw constant. Further, the control unit 5 controls the external It is possible to output three-phase AC power whose phase is shifted by 120 degrees to the terminals Tu, Tv, and Tw.
　次に、制御部５は、レグ２ｕ，２ｖ，２ｗが外部端子Ｔｕ，Ｔｖ，Ｔｗから外部へ出力された電荷量Ｑｏを取得する（ステップＳ２）。例えば電力変換装置１が電動車両に搭載され、外部端子Ｔｕ，Ｔｖ，Ｔｗが電動車両のモータに接続されている場合、制御部５は、電動車両側から、電荷量Ｑｏを表すデータとしてモータに流れた電気量ＡｈやＷｈを取得してもよい。また、制御部５は、モータに流れた電流値を電動車両等から取得してこれを積算することによって、電荷量Ｑｏを算出してもよい。あるいは、電力変換装置１が、レグ２ｕ，２ｖ，２ｗと外部端子Ｔｕ，Ｔｖ，Ｔｗとの間に流れる電流を検出する電流センサを備え、制御部５は、この電流センサで検出された電流値を積算することによって、電荷量Ｑｏを算出してもよい。 Next, the control unit 5 acquires the amount of charge Qo output from the external terminals Tu, Tv, and Tw of the legs 2u, 2v, and 2w to the outside (step S2). For example, when the power conversion device 1 is mounted on an electric vehicle and the external terminals Tu, Tv, and Tw are connected to the motor of the electric vehicle, the control unit 5 transmits data representing the amount of charge Qo to the motor from the electric vehicle side. The amount of electricity Ah or Wh that has flowed may be acquired. Further, the control unit 5 may calculate the amount of electric charge Qo by acquiring the value of the current flowing through the motor from an electric vehicle or the like and integrating the values. Alternatively, the power conversion device 1 includes a current sensor that detects the current flowing between the legs 2u, 2v, 2w and the external terminals Tu, Tv, Tw, and the control unit 5 controls the current value detected by the current sensor. The amount of charge Qo may be calculated by integrating .
　ステップＳ１で外部端子Ｔｕ，Ｔｖ，Ｔｗから外部へ電力が供給されると、レグ２ｕ，２ｖ，２ｗ内の第一蓄電部Ｂ１が放電する。そこで、制御部５は、直流電圧源４の開放端電圧ＶＯｐｓを相対的に上昇させるように各蓄電ブロックＢＢ及び／又は単位モジュールＥＭの接続状態を制御することによって、直流電圧源４からレグ２ｕ，２ｖ，２ｗ内の第一蓄電部Ｂ１へ電荷を移動させ、各第一蓄電部Ｂ１を充電する（ステップＳ３）。 When power is supplied to the outside from the external terminals Tu, Tv, Tw in step S1, the first power storage units B1 in the legs 2u, 2v, 2w are discharged. Therefore, the control unit 5 controls the connection state of each power storage block BB and/or unit module EM so as to relatively increase the open end voltage VOps of the DC voltage source 4. , 2v, and 2w, and charge each first power storage unit B1 (step S3).
　具体的には、例えば図８に示すように、直流電圧源４における加入状態の蓄電ブロックＢＢの数を、四個から五個に増加させることによって、開放端電圧ＶＯｐｓを上昇させる。これにより、開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗよりも開放端電圧ＶＯｐｓの方が相対的に高くなり、直流電圧源４からレグ２ｕ，２ｖ，２ｗへ電流が流れ、移動した電荷によって各第一蓄電部Ｂ１が充電される。 Specifically, as shown in FIG. 8, for example, the open circuit voltage VOps is increased by increasing the number of power storage blocks BB in the joining state in the DC voltage source 4 from four to five. As a result, the open circuit voltage VOps becomes relatively higher than the open circuit voltages VOu, VOv, and VOw, and current flows from the DC voltage source 4 to the legs 2u, 2v, and 2w, and the transferred charges cause each first storage Part B1 is charged.
　なお、制御部５は、直流電圧源４の開放端電圧ＶＯｐｓを開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗに対して相対的に上昇させることができればよく、例えばレグ２ｕ，２ｖ，２ｗ内の加入状態の単位モジュールＥＭの数を減少させることによって開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗを低下させてもよく、開放端電圧ＶＯｐｓの上昇と開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗの低下とを組み合わせてもよい。 Note that the control unit 5 only needs to be able to increase the open-circuit voltage VOps of the DC voltage source 4 relative to the open-circuit voltages VOu, VOv, and VOw, for example, depending on the joining state in the legs 2u, 2v, and 2w. The open circuit voltages VOu, VOv, VOw may be lowered by reducing the number of unit modules EM, or the increase in the open circuit voltage VOps and the decrease in the open circuit voltages VOu, VOv, VOw may be combined.
　次に、制御部５は、直流電圧源４からレグ２ｕ，２ｖ，２ｗへ移動した電荷量Ｑｍを取得する（ステップＳ４）。制御部５は、電流センサ７によって検出された、直流電圧源４からレグ２ｕ，２ｖ，２ｗへ流れる電流値を積算することによって、電荷量Ｑｍを取得することができる。 Next, the control unit 5 acquires the amount of charge Qm transferred from the DC voltage source 4 to the legs 2u, 2v, and 2w (step S4). The control unit 5 can acquire the amount of charge Qm by integrating the current values detected by the current sensor 7 and flowing from the DC voltage source 4 to the legs 2u, 2v, and 2w.
　次に、制御部５は、電荷量Ｑｍと電荷量Ｑｏとを比較する（ステップＳ５）。そして、電荷量Ｑｍが電荷量Ｑｏに満たなければ（ステップＳ５でＮＯ）、ステップＳ１～Ｓ４を繰り返し、直流電圧源４からレグ２ｕ，２ｖ，２ｗへの電荷の移動を継続する。一方、電荷量Ｑｍが電荷量Ｑｏに達すれば（ステップＳ５でＹＥＳ）、制御部５は、各蓄電ブロックＢＢ及び／又は単位モジュールＥＭの接続状態を制御し、開放端電圧ＶＯｐｓと開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗとを略等しくすることによって、直流電圧源４からレグ２ｕ，２ｖ，２ｗへの電荷を移動を停止させ（ステップＳ６）、再びステップＳ１へ処理を移行する。 Next, the control unit 5 compares the amount of charge Qm and the amount of charge Qo (step S5). If the charge amount Qm is less than the charge amount Qo (NO in step S5), steps S1 to S4 are repeated to continue moving the charge from the DC voltage source 4 to the legs 2u, 2v, and 2w. On the other hand, if the amount of charge Qm reaches the amount of charge Qo (YES in step S5), the control unit 5 controls the connection state of each power storage block BB and/or unit module EM, and increases the open end voltage VOps and the open end voltage Vou. , VOv, and VOw are made substantially equal to stop the transfer of charges from the DC voltage source 4 to the legs 2u, 2v, and 2w (step S6), and the process returns to step S1.
　ステップＳ５において、電荷量Ｑｏと電荷量Ｑｍとは、略同一であればよく、正確に同一でなくてもよい。例えば、電荷量Ｑｍは、０．８×Ｑｏ～１．２×Ｑｏであればよい。 In step S5, the amount of charge Qo and the amount of charge Qm only need to be approximately the same, and do not need to be exactly the same. For example, the amount of charge Qm may be between 0.8×Qo and 1.2×Qo.
　ステップＳ１～Ｓ６によって、制御部５は、レグ２ｕ，２ｖ，２ｗから外部へ出力された電荷量Ｑｏと略同一の電荷量Ｑｍを、直流電圧源４からレグ２ｕ，２ｖ，２ｗへ移動させることができる。これにより、各第一蓄電部Ｂ１の放電量を補充することができ、レグ２ｕ，２ｖ，２ｗによる三相電力出力動作を継続することが可能となる。従って、ステップＳ１～Ｓ６によれば、各単位モジュールＥＭの第一蓄電部Ｂ１を適切に充電することが容易となる。 In steps S1 to S6, the control unit 5 moves the amount of charge Qm, which is approximately the same as the amount of charge Qo outputted to the outside from the legs 2u, 2v, and 2w, from the DC voltage source 4 to the legs 2u, 2v, and 2w. I can do it. Thereby, the amount of discharge of each first power storage unit B1 can be replenished, and it becomes possible to continue the three-phase power output operation by the legs 2u, 2v, and 2w. Therefore, according to steps S1 to S6, it becomes easy to appropriately charge the first power storage section B1 of each unit module EM.
　なお、ステップＳ２、Ｓ４、Ｓ５で、レグ２から外部へ出力された電荷量Ｑｏに基づいて、直流電圧源４からレグ２へ電荷を移動させる例を示したが、制御部５は、レグ２ｕ，２ｖ，２ｗに関する電圧に基づいて直流電圧源４からレグ２へ電荷を移動させてもよい。具体的には、制御部５は、レグ２ｕ，２ｖ，２ｗに含まれる第一蓄電部Ｂ１の開放端電圧の合計値ＳＶｕ，ＳＶｖ，ＳＶｗをそれぞれ算出する。そして制御部５は、合計値ＳＶｕ，ＳＶｖ，ＳＶｗのうちいずれかが予め設定された第一基準電圧Ｖｒｅｆ１を下回った場合、ステップＳ３と同様、直流電圧源４の開放端電圧ＶＯｐｓを相対的に上昇させるように各蓄電ブロックＢＢ及び／又は単位モジュールＥＭの接続状態を制御することによって、直流電圧源４からレグ２ｕ，２ｖ，２ｗ内の第一蓄電部Ｂ１へ電荷を移動させ、各第一蓄電部Ｂ１を充電してもよい。 Note that in steps S2, S4, and S5, an example has been shown in which charges are transferred from the DC voltage source 4 to the leg 2 based on the amount of charge Qo outputted to the outside from the leg 2. , 2v, 2w may be used to transfer the charge from the DC voltage source 4 to the leg 2. Specifically, control unit 5 calculates total values SVu, SVv, and SVw of open-circuit voltages of first power storage unit B1 included in legs 2u, 2v, and 2w, respectively. Then, when any one of the total values SVu, SVv, and SVw is lower than the preset first reference voltage Vref1, the control unit 5 relatively adjusts the open-circuit voltage VOps of the DC voltage source 4, as in step S3. By controlling the connection state of each power storage block BB and/or unit module EM so as to increase the electric charge, the electric charge is moved from the DC voltage source 4 to the first power storage part B1 in the legs 2u, 2v, 2w, and each first Power storage unit B1 may be charged.
　合計値ＳＶｕ，ＳＶｖ，ＳＶｗは、各レグにおけるすべての単位モジュールＥＭが加入状態のときの開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗに相当する。電力変換装置１は、各第一蓄電部Ｂ１の電圧を検出する電圧センサを備え、制御部５は、電圧センサで検出された各第一蓄電部Ｂ１の開放端電圧を取得することによって、合計値ＳＶｕ，ＳＶｖ，ＳＶｗを算出することができる。第一基準電圧Ｖｒｅｆ１としては、レグ２ｕ，２ｖ，２ｗを充電する必要が生じる合計値ＳＶｕ，ＳＶｖ，ＳＶｗの値を予め適宜設定することができる。 The total values SVu, SVv, and SVw correspond to the open circuit voltages Vou, VOv, and VOw when all unit modules EM in each leg are in the joining state. Power conversion device 1 includes a voltage sensor that detects the voltage of each first power storage unit B1, and control unit 5 obtains the open end voltage of each first power storage unit B1 detected by the voltage sensor, thereby calculating the total The values SVu, SVv, and SVw can be calculated. As the first reference voltage Vref1, the value of the total values SVu, SVv, and SVw at which it is necessary to charge the legs 2u, 2v, and 2w can be appropriately set in advance.
　合計値ＳＶｕ，ＳＶｖ，ＳＶｗは、レグ２ｕ，２ｖ，２ｗにおける充電量が減少すると低下する。従って、レグ２ｕ，２ｖ，２ｗが放電して合計値ＳＶｕ，ＳＶｖ，ＳＶｗのうちいずれかが第一基準電圧Ｖｒｅｆ１を下回った場合に直流電圧源４からレグ２ｕ，２ｖ，２ｗ内の第一蓄電部Ｂ１へ電荷を移動させることによって、各単位モジュールＥＭの第一蓄電部Ｂ１を適切に充電することが容易となる。 The total values SVu, SVv, and SVw decrease as the amount of charge in the legs 2u, 2v, and 2w decreases. Therefore, when the legs 2u, 2v, 2w are discharged and any one of the total values SVu, SVv, SVw becomes lower than the first reference voltage Vref1, the DC voltage source 4 supplies the first storage battery in the legs 2u, 2v, 2w. By moving the charge to portion B1, it becomes easy to appropriately charge first power storage portion B1 of each unit module EM.
　次に、外部端子Ｔｕ，Ｔｖ，Ｔｗに接続された外部負荷から電力を回収する回生制御について説明する。図５は、図１に示す電力変換装置の回生制御に係る動作の一例を示すフローチャートである。外部端子Ｔｕ，Ｔｖ，Ｔｗに接続された外部負荷から回生電流が外部端子Ｔｕ，Ｔｖ，Ｔｗに入力された場合、制御部５は、レグ２ｕ，２ｖ，２ｗの各単位モジュールＥＭの接続状態を制御することによって、外部端子Ｔｕ，Ｔｖ，Ｔｗで得られた回生電流を、レグ２ｕ，２ｖ，２ｗの各第一蓄電部Ｂ１に充電する（ステップＳ１１）。 Next, regeneration control for recovering power from external loads connected to external terminals Tu, Tv, and Tw will be described. FIG. 5 is a flowchart showing an example of an operation related to regeneration control of the power converter shown in FIG. When regenerative current is input to the external terminals Tu, Tv, Tw from the external loads connected to the external terminals Tu, Tv, Tw, the control unit 5 controls the connection state of each unit module EM of the legs 2u, 2v, 2w. By controlling, the regenerative current obtained at the external terminals Tu, Tv, and Tw is charged to each first power storage unit B1 of the legs 2u, 2v, and 2w (step S11).
　次に、制御部５は、レグ２ｕ，２ｖ，２ｗに充電された電荷量Ｑｉを取得する（ステップＳ１２）。制御部５は、ステップＳ２と同様、例えば電動車両等の外部から得られたデータに基づき電荷量Ｑｉを取得してもよく、図略の電流センサで検出された電流値を積算することによって、電荷量Ｑｉを算出してもよい。 Next, the control unit 5 acquires the amount of charge Qi charged in the legs 2u, 2v, and 2w (step S12). Similarly to step S2, the control unit 5 may obtain the charge amount Qi based on data obtained from an external source such as an electric vehicle, and by integrating current values detected by a current sensor (not shown), The amount of charge Qi may also be calculated.
　次に、制御部５は、直流電圧源４の開放端電圧ＶＯｐｓを相対的に低下させるように各蓄電ブロックＢＢ及び／又は単位モジュールＥＭの接続状態を制御することによって、レグ２ｕ，２ｖ，２ｗ内の第一蓄電部Ｂ１から直流電圧源４へ電荷を移動させ、直流電圧源４の各第二蓄電部Ｂ２を充電する（ステップＳ１３）。 Next, the control unit 5 controls the connection state of each power storage block BB and/or unit module EM so as to relatively reduce the open end voltage VOps of the DC voltage source 4. The charge is transferred from the first power storage unit B1 in the DC voltage source 4 to the DC voltage source 4, and each second power storage unit B2 of the DC voltage source 4 is charged (step S13).
　具体的には、例えば図９に示すように、直流電圧源４における加入状態の蓄電ブロックＢＢの数を、四個から三個に減少させることによって、開放端電圧ＶＯｐｓを低下させる。これにより、開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗよりも開放端電圧ＶＯｐｓの方が相対的に低くなり、レグ２ｕ，２ｖ，２ｗから直流電圧源４へ電流が流れ、移動した電荷によって各第二蓄電部Ｂ２が充電される。 Specifically, as shown in FIG. 9, for example, the open circuit voltage VOps is lowered by reducing the number of power storage blocks BB in the joining state in the DC voltage source 4 from four to three. As a result, the open-circuit voltage VOps becomes relatively lower than the open-circuit voltages VOu, VOv, and VOw, and current flows from the legs 2u, 2v, and 2w to the DC voltage source 4, and the transferred charges cause each second storage Part B2 is charged.
　なお、制御部５は、直流電圧源４の開放端電圧ＶＯｐｓを開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗに対して相対的に低下させることができればよく、例えばレグ２ｕ，２ｖ，２ｗ内の加入状態の単位モジュールＥＭの数を増加させることによって開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗを上昇させてもよく、開放端電圧ＶＯｐｓの低下と開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗの上昇とを組み合わせてもよい。 Note that the control unit 5 only needs to be able to lower the open-circuit voltage VOps of the DC voltage source 4 relative to the open-circuit voltages VOu, VOv, and VOw; The open circuit voltages VOu, VOv, VOw may be increased by increasing the number of unit modules EM, or the decrease in the open circuit voltage VOps and the increase in the open circuit voltages VOu, VOv, VOw may be combined.
　次に、制御部５は、レグ２ｕ，２ｖ，２ｗから直流電圧源４へ移動した電荷量Ｑｎを取得する（ステップＳ１４）。制御部５は、電流センサ７によって検出された、レグ２ｕ，２ｖ，２ｗから直流電圧源４へ流れる電流値を積算することによって、電荷量Ｑｎを取得することができる。 Next, the control unit 5 acquires the amount of charge Qn transferred from the legs 2u, 2v, and 2w to the DC voltage source 4 (step S14). The control unit 5 can acquire the amount of charge Qn by integrating the current values detected by the current sensor 7 and flowing from the legs 2u, 2v, and 2w to the DC voltage source 4.
　次に、制御部５は、電荷量Ｑｎと電荷量Ｑｉとを比較する（ステップＳ１５）。そして、電荷量Ｑｎが電荷量Ｑｉに満たなければ（ステップＳ１５でＮＯ）、ステップＳ１１～Ｓ１４を繰り返し、レグ２ｕ，２ｖ，２ｗから直流電圧源４への電荷の移動を継続する。一方、電荷量Ｑｎが電荷量Ｑｉに達すれば（ステップＳ１５でＹＥＳ）、制御部５は、各蓄電ブロックＢＢ及び／又は単位モジュールＥＭの接続状態を制御し、開放端電圧ＶＯｐｓと開放端電圧ＶＯｕ，ＶＯｖ，ＶＯｗとを略等しくすることによって、レグ２ｕ，２ｖ，２ｗから直流電圧源４への電荷を移動を停止させ（ステップＳ１６）、再びステップＳ１１へ処理を移行する。 Next, the control unit 5 compares the amount of charge Qn and the amount of charge Qi (step S15). If the charge amount Qn is less than the charge amount Qi (NO in step S15), steps S11 to S14 are repeated to continue moving the charges from the legs 2u, 2v, and 2w to the DC voltage source 4. On the other hand, if the amount of charge Qn reaches the amount of charge Qi (YES in step S15), the control unit 5 controls the connection state of each power storage block BB and/or unit module EM, and increases the open end voltage VOps and the open end voltage VOut. , VOv, and VOw are made substantially equal to stop the transfer of charges from the legs 2u, 2v, and 2w to the DC voltage source 4 (step S16), and the process returns to step S11.
　ステップＳ１５において、電荷量Ｑｉと電荷量Ｑｎとは、略同一であればよく、正確に同一でなくてもよい。例えば、電荷量Ｑｎは、０．８×Ｑｉ～１．２×Ｑｉであればよい。 In step S15, the amount of charge Qi and the amount of charge Qn only need to be approximately the same, and do not need to be exactly the same. For example, the amount of charge Qn may be 0.8×Qi to 1.2×Qi.
　ステップＳ１１～Ｓ１６によって、制御部５は、外部からレグ２ｕ，２ｖ，２ｗへ回生された電荷量Ｑｉと略同一の電荷量Ｑｎを、レグ２ｕ，２ｖ，２ｗから直流電圧源４へ移動させることができる。これにより、外部からレグ２ｕ，２ｖ，２ｗへ回生され、各第一蓄電部Ｂ１に充電された充電量を、直流電圧源４の各第二蓄電部Ｂ２に移動させることができるので、各第一蓄電部Ｂ１が過充電になることを防止しつつ、外部から回生電力を受け入れることが可能となる。 Through steps S11 to S16, the control unit 5 moves the amount of charge Qn, which is substantially the same as the amount of charge Qi regenerated from the outside to the legs 2u, 2v, and 2w, from the legs 2u, 2v, and 2w to the DC voltage source 4. I can do it. As a result, the amount of charge regenerated from the outside to legs 2u, 2v, 2w and charged in each first power storage unit B1 can be transferred to each second power storage unit B2 of DC voltage source 4, so that each It becomes possible to receive regenerated power from the outside while preventing power storage unit B1 from being overcharged.
　なお、ステップＳ１２、Ｓ１４、Ｓ１５で、外部からレグ２へ充電された電荷量Ｑｉに基づいて、レグ２から直流電圧源４へ電荷を移動させる例を示したが、制御部５は、レグ２ｕ，２ｖ，２ｗに関する電圧に基づいてレグ２から直流電圧源４へ電荷を移動させてもよい。 Note that in steps S12, S14, and S15, an example has been shown in which charges are transferred from the leg 2 to the DC voltage source 4 based on the amount of charge Qi charged to the leg 2 from the outside. , 2v, 2w may be used to transfer the charge from the leg 2 to the DC voltage source 4.
　具体的には、制御部５は、レグ２ｕ，２ｖ，２ｗに含まれる第一蓄電部Ｂ１の開放端電圧の合計値ＳＶｕ，ＳＶｖ，ＳＶｗをそれぞれ算出する。そして制御部５は、合計値ＳＶｕ，ＳＶｖ，ＳＶｗのうちいずれかが予め設定された第二基準電圧Ｖｒｅｆ２を上回った場合、ステップＳ１３と同様、直流電圧源４の開放端電圧ＶＯｐｓを相対的に低下させるように各蓄電ブロックＢＢ及び／又は単位モジュールＥＭの接続状態を制御することによって、レグ２ｕ，２ｖ，２ｗ内の第一蓄電部Ｂ１から直流電圧源４へ電荷を移動させ、各第二蓄電部Ｂ２を充電してもよい。 Specifically, control unit 5 calculates total values SVu, SVv, and SVw of the open end voltages of first power storage unit B1 included in legs 2u, 2v, and 2w, respectively. Then, when any one of the total values SVu, SVv, and SVw exceeds the preset second reference voltage Vref2, the control unit 5 relatively adjusts the open-circuit voltage VOps of the DC voltage source 4, as in step S13. By controlling the connection state of each power storage block BB and/or unit module EM so as to lower the electric charge, the charge is moved from the first power storage section B1 in the legs 2u, 2v, 2w to the DC voltage source 4, and each second Power storage unit B2 may be charged.
　第二基準電圧Ｖｒｅｆ２としては、レグ２ｕ，２ｖ，２ｗに回生電流が充電された場合にレグ２ｕ，２ｖ，２ｗを放電させる必要が生じる合計値ＳＶｕ，ＳＶｖ，ＳＶｗの値を予め適宜設定することができる。 As the second reference voltage Vref2, the value of the total value SVu, SVv, SVw that will cause it to be necessary to discharge the legs 2u, 2v, 2w when the legs 2u, 2v, 2w are charged with regenerative current should be set appropriately in advance. I can do it.
　合計値ＳＶｕ，ＳＶｖ，ＳＶｗは、レグ２ｕ，２ｖ，２ｗにおける充電量が増大すると上昇する。従って、レグ２ｕ，２ｖ，２ｗが充電されて合計値ＳＶｕ，ＳＶｖ，ＳＶｗのうちいずれかが第二基準電圧Ｖｒｅｆ２を上回った場合にレグ２ｕ，２ｖ，２ｗから直流電圧源４の第二蓄電部Ｂ２へ電荷を移動させることによって、外部から回生電力を適切に回収することが容易となる。 The total values SVu, SVv, and SVw increase as the amount of charge in the legs 2u, 2v, and 2w increases. Therefore, when the legs 2u, 2v, 2w are charged and any one of the total values SVu, SVv, SVw exceeds the second reference voltage Vref2, the legs 2u, 2v, 2w are charged to the second storage unit of the DC voltage source 4. By moving the charge to B2, it becomes easy to appropriately recover regenerated power from the outside.
　次に、レグ２ｕ，２ｖ，２ｗ相互間の充電量を均衡させるためのバランス制御について説明する。電力変換装置１による電力変換や電力回生を行う過程で、レグ２ｕ，２ｖ，２ｗ相互間の第一蓄電部Ｂ１による充電量が不均衡になる場合がある。レグ２ｕ，２ｖ，２ｗ相互間の充電量が不均衡になると、相間で電圧に差が生じ、不都合である。そこで、下記のバランス制御を行うことによって、レグ２ｕ，２ｖ，２ｗ相互間の充電量の不均衡を低減する。 Next, balance control for balancing the amount of charge between the legs 2u, 2v, and 2w will be described. During the process of power conversion and power regeneration by the power conversion device 1, the amount of charge by the first power storage unit B1 between the legs 2u, 2v, and 2w may become unbalanced. If the charges between the legs 2u, 2v, and 2w become unbalanced, a voltage difference will occur between the phases, which is inconvenient. Therefore, by performing the balance control described below, the imbalance in the amount of charge between the legs 2u, 2v, and 2w is reduced.
　図６は、図１に示す電力変換装置のバランス制御に係る動作の一例を示すフローチャートである。まず、制御部５は、レグ２ｕ，２ｖ，２ｗに含まれる第一蓄電部Ｂ１の開放端電圧の合計値ＳＶｕ，ＳＶｖ，ＳＶｗをそれぞれ算出して比較する（ステップＳ２１）。 FIG. 6 is a flowchart illustrating an example of an operation related to balance control of the power conversion device illustrated in FIG. 1. First, control unit 5 calculates and compares total values SVu, SVv, and SVw of open-circuit voltages of first power storage unit B1 included in legs 2u, 2v, and 2w, respectively (step S21).
　次に、制御部５は、合計値ＳＶが最大のレグ２の開放端電圧ＶＯを相対的に上昇させるように、レグ２ｕ，２ｖ，２ｗの各単位モジュールＥＭの接続状態を制御する（ステップＳ２２）。 Next, the control unit 5 controls the connection state of each unit module EM of the legs 2u, 2v, and 2w so as to relatively increase the open end voltage VO of the leg 2 with the largest total value SV (step S22 ).
　図１０は、レグ２ｕの合計値ＳＶｕが最大、レグ２ｗの合計値ＳＶｗが最小の場合を示す説明図である。レグ２ｕの合計値ＳＶｕが最大の場合、制御部５は、図１０に示すように、レグ２ｕの加入状態の単位モジュールＥＭの数を増加させることによって、開放端電圧ＶＯｕを相対的に上昇させる。これにより、合計値ＳＶｕが最も大きく、従って充電量が最も多いレグ２ｕから、他のレグ２ｖ，２ｗへ電荷が移動するので、レグ２ｕ，２ｖ，２ｗ相互間の充電量の不均衡が低減する。 FIG. 10 is an explanatory diagram showing a case where the total value SVu of leg 2u is the maximum and the total value SVw of leg 2w is the minimum. When the total value SVu of the leg 2u is the maximum, the control unit 5 relatively increases the open end voltage Vou by increasing the number of unit modules EM in the joined state of the leg 2u, as shown in FIG. . As a result, charge is transferred from leg 2u, which has the largest total value SVu and therefore the highest amount of charge, to the other legs 2v and 2w, reducing the imbalance in the amount of charge between legs 2u, 2v, and 2w. .
　制御部５は、さらに、合計値ＳＶが最小のレグ２ｗの加入状態の単位モジュールＥＭの数を、図１０に示すように減少させてもよい。これにより、レグ２ｗへの電荷の移動量が、レグ２ｖへの電荷の移動量よりも増大するので、レグ２ｕ，２ｖ，２ｗ相互間の充電量の不均衡の低減効果がさらに増大する。 The control unit 5 may further reduce the number of unit modules EM in the joining state of the leg 2w with the smallest total value SV, as shown in FIG. 10. As a result, the amount of charge transferred to leg 2w is greater than the amount of charge transferred to leg 2v, so that the effect of reducing the imbalance in the amount of charge between legs 2u, 2v, and 2w is further increased.
　なお、制御部５は、合計値ＳＶが最大のレグ２の開放端電圧ＶＯを相対的に上昇させればよく、合計値ＳＶが最大のレグ２の開放端電圧ＶＯそのものを上昇させる例に限らない。制御部５は、合計値ＳＶが最大のレグ２以外の開放端電圧ＶＯを低下させることによって、合計値ＳＶが最大のレグ２の開放端電圧ＶＯを相対的に上昇させてもよい。 Note that the control unit 5 only needs to relatively increase the open-circuit voltage VO of leg 2 with the largest total value SV, and is limited to the example in which the open-circuit voltage VO of leg 2 with the largest total value SV itself is increased. do not have. The control unit 5 may relatively increase the open end voltage VO of the leg 2 having the maximum total value SV by lowering the open end voltage VO of the legs other than the leg 2 having the maximum total value SV.
　また、電力変換装置１は、三つのレグ２ｕ，２ｖ，２ｗを備える例に限らない。電力変換装置１は、レグを一つ備える単相の電力変換装置であってもよく、レグを二つ、あるいは四つ以上備える電力変換装置であってもよい。 Furthermore, the power conversion device 1 is not limited to the example including the three legs 2u, 2v, and 2w. The power converter 1 may be a single-phase power converter having one leg, or may be a power converter having two, four or more legs.
　１　電力変換装置
　２，２ｕ，２ｖ，２ｗ　レグ
　３Ｈ　上アーム
　３Ｌ　下アーム
　４　直流電圧源
　５　制御部
　６　三相インバータ
　７　電流センサ
　Ｂ１　第一蓄電部
　Ｂ２　第二蓄電部
　ＢＢ　蓄電ブロック
　Ｃ　キャパシタ
　ＥＭ　単位モジュール
　Ｌ　インダクタ
　Ｑｉ，Ｑｍ，Ｑｎ，Ｑｏ　電荷量
　ＳＷ１，ＳＷ２，ＳＷ３，ＳＷ４　スイッチング素子（第一切換回路、第二切換回路）
　ＳＶ，ＳＶｕ，ＳＶｖ，ＳＶｗ　合計値
　Ｔ１　端子（第一端子）
　Ｔ２　端子（第二端子）
　Ｔ３　端子（第三端子）
　Ｔ４　端子（第四端子）
　Ｔｕ，Ｔｖ，Ｔｗ　外部端子
　ＶＯ，ＶＯｐｓ，ＶＯｕ，ＶＯｖ，ＶＯｗ　開放端電圧
　Ｖｒｅｆ１　第一基準電圧
　ＷＬ，ＷＨ　電力線
  1 Power converter 2, 2u, 2v, 2w Leg 3H Upper arm 3L Lower arm 4 DC voltage source 5 Control unit 6 Three-phase inverter 7 Current sensor B1 First power storage unit B2 Second power storage unit BB Power storage block C Capacitor EM Unit module L Inductor Qi, Qm, Qn, Qo Charge amount SW1, SW2, SW3, SW4 Switching element (first switching circuit, second switching circuit)
SV, SVu, SVv, SVw total value T1 terminal (first terminal)
T2 terminal (second terminal)
T3 terminal (third terminal)
T4 terminal (fourth terminal)
Tu, Tv, Tw External terminal VO, VOps, VOu, VOv, VOw Open end voltage Vref1 First reference voltage WL, WH Power line

Claims (13)

  1. 　上アームとインダクタと下アームとが、この順に直列接続されたレグと、
    　複数の蓄電ブロックが直列接続された直列回路を含むと共に、前記レグと並列に接続された直流電圧源と、
    　制御部とを備え、
    　前記上アーム及び前記下アームのそれぞれは、複数の単位モジュールが直列接続された直列回路を含み、
    　前記各単位モジュールは、
    　第一及び第二端子と、
    　電荷を蓄える第一蓄電部と、
    　前記第一及び第二端子へ前記第一蓄電部を接続する加入状態と前記第一及び第二端子間を短絡する離脱状態とを含む接続状態を切り換える第一切換回路とを含み、
    　前記各蓄電ブロックは、
    　第三及び第四端子と、
    　電荷を蓄える第二蓄電部と、
    　前記第三及び第四端子へ前記第二蓄電部を接続する加入状態と前記第三及び第四端子間を短絡する離脱状態とを含む接続状態を切り換える第二切換回路とを含み、
    　前記制御部は、
    　前記各第一切換回路による接続状態の切り替えを制御することによって、前記レグに所定の電力を出力させ、
    　前記各第一切換回路及び／又は前記各第二切換回路による接続状態の切り替えを制御することによって、前記直流電圧源と前記レグとの間での電荷の移動を制御する電力変換装置。     A leg in which an upper arm, an inductor, and a lower arm are connected in series in this order;
    a DC voltage source including a series circuit in which a plurality of power storage blocks are connected in series, and connected in parallel with the leg;
    It is equipped with a control section,
    Each of the upper arm and the lower arm includes a series circuit in which a plurality of unit modules are connected in series,
    Each unit module is
    first and second terminals;
    a first power storage unit that stores electric charge;
    a first switching circuit that switches between connection states including a connection state in which the first power storage unit is connected to the first and second terminals and a disconnection state in which the first and second terminals are short-circuited;
    Each of the electricity storage blocks is
    third and fourth terminals;
    a second power storage unit that stores electric charge;
    a second switching circuit that switches a connection state including a connection state in which the second power storage unit is connected to the third and fourth terminals and a disconnection state in which the third and fourth terminals are short-circuited;
    The control unit includes:
    controlling the switching of the connection state by each of the first switching circuits to output a predetermined power to the leg;
    A power conversion device that controls charge transfer between the DC voltage source and the leg by controlling switching of connection states by each of the first switching circuits and/or the second switching circuits.
  2. 　前記各第一蓄電部及び前記各第二蓄電部は、二次電池であり、
    　前記各第二蓄電部は、前記各第一蓄電部よりも蓄電容量が大きい請求項１に記載の電力変換装置。     Each of the first power storage unit and each of the second power storage unit is a secondary battery,
    The power conversion device according to claim 1, wherein each of the second power storage units has a larger power storage capacity than each of the first power storage units.
  3. 　前記各第一蓄電部は、前記各第二蓄電部よりも電流定格が大きい請求項１に記載の電力変換装置。 The power conversion device according to claim 1, wherein each of the first power storage units has a higher current rating than each of the second power storage units.
  4. 　前記制御部は、前記直流電圧源の電圧を相対的に上昇させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記直流電圧源から前記レグへ電荷を移動させる請求項１に記載の電力変換装置。 The control unit controls switching of the connection state by each of the first switching circuits and/or the second switching circuits so as to relatively increase the voltage of the DC voltage source. The power conversion device according to claim 1, wherein the electric charge is transferred from the leg to the leg.
  5. 　前記制御部は、前記レグから外部へ出力された電荷量と略同一の電荷量を、前記直流電圧源から前記レグへ移動させるように、前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御する請求項４に記載の電力変換装置。 The control unit controls each of the first switching circuits and/or the second switching circuits so that substantially the same amount of charge as the amount of charge outputted from the leg to the outside is transferred from the DC voltage source to the leg. The power conversion device according to claim 4, wherein switching of the connection state by a circuit is controlled.
  6. 　前記制御部は、前記レグに含まれる前記第一蓄電部の開放端電圧の合計が、予め設定された第一基準電圧を下回った場合、前記直流電圧源の出力電圧を相対的に上昇させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記直流電圧源から前記レグへ電荷を移動させる請求項４に記載の電力変換装置。 The control unit is configured to relatively increase the output voltage of the DC voltage source when the total open end voltage of the first power storage unit included in the leg is lower than a preset first reference voltage. 5. The power conversion device according to claim 4, wherein the electric charge is transferred from the DC voltage source to the leg by controlling switching of the connection state by each of the first switching circuit and/or the second switching circuit.
  7. 　前記制御部は、前記直流電圧源の電圧を相対的に低下させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記レグから前記直流電圧源へ電荷を移動させる請求項１に記載の電力変換装置。 The control unit controls switching of the connection state by each of the first switching circuits and/or each of the second switching circuits so as to relatively reduce the voltage of the DC voltage source. The power conversion device according to claim 1, wherein the power conversion device transfers charge to a DC voltage source.
  8. 　前記制御部は、外部から前記レグへ入力された電荷量と略同一の電荷量を、前記レグから前記直流電圧源へ移動させるように、前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御する請求項７に記載の電力変換装置。 The control unit controls each of the first switching circuits and/or the second switching circuits so as to transfer substantially the same amount of charge from the leg to the DC voltage source as the amount of charge input from the outside to the leg. The power conversion device according to claim 7, wherein switching of the connection state by a circuit is controlled.
  9. 　前記制御部は、前記レグに含まれる前記第一蓄電部の開放端電圧の合計が、予め設定された第二基準電圧を上回った場合、前記直流電圧源の出力電圧を相対的に低下させるように前記各第一切換回路及び／又は前記各第二切換回路による前記接続状態の切り替えを制御することによって、前記レグから前記直流電圧源へ電荷を移動させる請求項７に記載の電力変換装置。 The control unit is configured to relatively reduce the output voltage of the DC voltage source when the total open end voltage of the first power storage unit included in the leg exceeds a preset second reference voltage. The power conversion device according to claim 7, wherein the electric charge is transferred from the leg to the DC voltage source by controlling switching of the connection state by each of the first switching circuit and/or the second switching circuit.
  10. 　前記制御部は、さらに、前記レグ内における前記上アームの電圧と、前記レグ内における前記下アームの電圧との比率を変化させることによって、前記レグによる電力変換を制御する請求項１～９のいずれか１項に記載の電力変換装置。 The control unit further controls power conversion by the leg by changing a ratio between the voltage of the upper arm in the leg and the voltage of the lower arm in the leg. The power conversion device according to any one of the items.
  11. 　前記各第一切換回路は、ハーフブリッジ又はフルブリッジのブリッジ回路であり、
    　前記各第二切替回路は、ハーフブリッジ又はフルブリッジのブリッジ回路である請求項１～９のいずれか１項に記載の電力変換装置。     Each of the first switching circuits is a half-bridge or full-bridge bridge circuit,
    The power conversion device according to claim 1, wherein each of the second switching circuits is a half-bridge or full-bridge bridge circuit.
  12. 　前記レグを複数備え、
    　前記複数のレグは並列接続され、
    　前記制御部は、さらに、前記各レグに含まれる前記第一蓄電部の開放端電圧の合計値を比較し、相対的に前記合計値が大きいレグの電圧を相対的に上昇させるように前記各レグの第一切換回路による前記接続状態の切り替えを制御することによって、前記相対的に前記合計値が大きいレグから、前記相対的に前記合計値が小さいレグへ電荷を移動させる請求項１～９のいずれか１項に記載の電力変換装置。     comprising a plurality of the legs;
    the plurality of legs are connected in parallel;
    The control unit further compares the total value of open end voltages of the first power storage units included in each of the legs, and controls each of the legs so as to relatively increase the voltage of the leg having a relatively large total value. 10. Charges are transferred from the leg with the relatively large total value to the leg with the relatively small total value by controlling switching of the connection state by a first switching circuit of the leg. The power conversion device according to any one of the above.
  13. 　前記レグを三つ備え、
    　前記三つのレグは、互いに並列接続されて三相インバータを構成する請求項１～９のいずれか１項に記載の電力変換装置。
          comprising three of the legs;
    The power conversion device according to claim 1, wherein the three legs are connected in parallel to each other to constitute a three-phase inverter.
PCT/JP2023/025240 2022-07-14 2023-07-07 Power converter WO2024014404A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015012769A (en) * 2013-07-02 2015-01-19 株式会社日立製作所 Power conversion device and electromechanical energy conversion system
US20150162848A1 (en) * 2012-08-07 2015-06-11 Abb Ab Method and device for controlling a multilevel converter
CN211127644U (en) * 2019-12-30 2020-07-28 珠海格力电器股份有限公司 Variable-current control device and motor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150162848A1 (en) * 2012-08-07 2015-06-11 Abb Ab Method and device for controlling a multilevel converter
JP2015012769A (en) * 2013-07-02 2015-01-19 株式会社日立製作所 Power conversion device and electromechanical energy conversion system
CN211127644U (en) * 2019-12-30 2020-07-28 珠海格力电器股份有限公司 Variable-current control device and motor

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