WO2024127578A1 - Uninterruptible power supply system - Google Patents
Uninterruptible power supply system Download PDFInfo
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- WO2024127578A1 WO2024127578A1 PCT/JP2022/046179 JP2022046179W WO2024127578A1 WO 2024127578 A1 WO2024127578 A1 WO 2024127578A1 JP 2022046179 W JP2022046179 W JP 2022046179W WO 2024127578 A1 WO2024127578 A1 WO 2024127578A1
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- power
- power supply
- load
- current
- bypass
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- 239000004065 semiconductor Substances 0.000 claims abstract description 102
- 238000001514 detection method Methods 0.000 claims description 41
- 238000010586 diagram Methods 0.000 description 27
- 230000002457 bidirectional effect Effects 0.000 description 12
- 239000003990 capacitor Substances 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 11
- 230000004913 activation Effects 0.000 description 8
- 230000002779 inactivation Effects 0.000 description 6
- 238000012423 maintenance Methods 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
Definitions
- This disclosure relates to an uninterruptible power supply system, and in particular to an uninterruptible power supply system having multiple uninterruptible power supply devices connected in parallel to a load.
- Patent Document 1 discloses an uninterruptible power supply including a bypass switch, a small semiconductor switch, and a power converter connected in parallel between an AC power source and a load.
- the power converter includes a converter that converts AC power supplied from the AC power source into DC power, and an inverter that converts the DC power into AC power and supplies it to the load.
- the inverter power supply mode is executed and the bypass switch and semiconductor switch are turned off.
- the converter also converts AC power from the AC power supply into DC power. This DC power is stored in the battery and is also provided to the inverter.
- the inverter converts the DC power into AC power and supplies it to the load.
- the bypass power supply mode is executed, the operation of the power converter is stopped, and the bypass switch and semiconductor switch are turned on. To prevent the semiconductor switch from overheating due to current, the semiconductor switch is turned off after a specified time has elapsed. AC power is supplied to the load from the AC power source via the bypass switch.
- the battery power supply mode is activated, the converter operation is stopped, and the inverter converts the DC power of the battery into AC power and supplies it to the load. Therefore, even if a power outage occurs in the AC power supply, the load can continue to operate as long as DC power is stored in the battery.
- uninterruptible power supplies have the problem that losses occur mainly in the power converter, resulting in low efficiency of around 90-96%.
- uninterruptible power supplies with a bypass ECO power supply mode have attracted attention.
- These uninterruptible power supplies are equipped with a large semiconductor switch and a power converter that are connected in parallel between the AC power supply and the load.
- the bypass ECO power supply mode is executed, the semiconductor switch is turned on, and AC power from the AC power supply is supplied to the load via the semiconductor switch.
- the battery power supply mode is executed, the semiconductor switch is turned off, and the inverter included in the power converter converts the battery's DC power to AC power and supplies it to the load.
- losses occur mainly in the semiconductor switch, but because the losses in the semiconductor switch are smaller than the losses in the power converter, a high efficiency of 99% can be achieved.
- the primary objective of this disclosure is to provide an uninterruptible power supply system that enables miniaturization and cost reduction of semiconductor switches.
- the uninterruptible power supply system disclosed herein includes a plurality of uninterruptible power supply devices connected in parallel to a load.
- Each uninterruptible power supply device includes a semiconductor switch that is turned on when the first AC power supply is healthy and turned off when the first AC power supply is interrupted, a reactor that is connected in series with the semiconductor switch between the first AC power supply and the load, and a power converter that converts DC power supplied from a DC power supply into AC power and supplies it to the load when the first AC power supply is interrupted.
- each of the multiple uninterruptible power supply devices includes a semiconductor switch and a reactor connected in series between the first AC power supply and the load, so that when each semiconductor switch is turned on, the load current is diverted to the series connection of the multiple semiconductor switches and reactors. Therefore, compared to a case where there is no reactor, the variation in the magnitude of the current flowing through the multiple semiconductor switches can be reduced, and the semiconductor switches can be made smaller and less expensive.
- FIG. 1 is a circuit block diagram showing a configuration of an uninterruptible power supply system according to an embodiment of the present disclosure.
- FIG. 2 is a block diagram showing a configuration of a control device shown in FIG. 1 .
- 2 is a circuit block diagram showing a configuration of the uninterruptible power supply device shown in FIG. 1.
- FIG. 4 is a circuit block diagram showing a configuration of the bypass module shown in FIG. 3 .
- FIG. 5 is a diagram showing a table stored in a storage unit shown in FIG. 4 .
- FIG. 4 is a circuit block diagram showing a configuration of the power module shown in FIG. 3 .
- 7 is a block diagram showing a configuration of a portion of the control unit shown in FIG. 6 that is related to inverter control.
- FIG. 1 is a circuit block diagram showing a main part of an uninterruptible power supply system serving as a comparative example of an embodiment.
- FIG. 11 is a circuit block diagram for explaining a bypass ECO power supply mode in a comparative example.
- FIG. 10 is a diagram illustrating the VI characteristics of the semiconductor switch shown in FIG.
- FIG. 4 is a circuit block diagram for explaining a bypass ECO power supply mode in the embodiment.
- 12 is a diagram illustrating the VI characteristics of the reactor shown in FIG. 11.
- 12 is a diagram illustrating an example of a VI characteristic of a series connection of the reactor and the semiconductor switch shown in FIG. 11.
- FIG. 1 is a circuit block diagram showing the configuration of an uninterruptible power supply system 1 according to one embodiment of the present disclosure.
- the uninterruptible power supply system 1 comprises N uninterruptible power supplies (UPS) U1-UN, N batteries B1-BN, a current detector 2, a communication line 3, an operation unit 4, and a control device 5.
- N is an integer equal to or greater than 2.
- the uninterruptible power supplies U1-UN may be collectively and representatively referred to as uninterruptible power supply U.
- the batteries B1-BN may be collectively and representatively referred to as battery B.
- Each uninterruptible power supply U includes a bypass terminal T1, an input terminal T2, a DC terminal T3, and an output terminal T4.
- the bypass terminal T1 is connected to a bypass AC power supply 6 (first AC power supply).
- the input terminal T2 is connected to an AC power supply 7 (second AC power supply).
- the bypass AC power supply 6 and the AC power supply 7 may be provided separately or may be the same.
- Each of the AC power supplies 6, 7 may be a commercial AC power supply or a generator.
- Each of the AC power supplies 6, 7 supplies AC power to the uninterruptible power supplies U1 to UN.
- the DC terminals T3 of the uninterruptible power supplies U1 to UN are connected to batteries B1 to BN (power storage devices), respectively.
- Each of the batteries B1 to BN stores DC power.
- a single large battery may be provided in place of the batteries B1 to BN, and the DC terminals T3 of the uninterruptible power supplies U1 to UN may be connected to the single large battery.
- a capacitor may be provided in place of the battery B.
- the output terminals T4 of the uninterruptible power supplies U1 to UN are all connected to a node N1, which is connected to a load 8.
- the load 8 is driven by AC power supplied from the uninterruptible power supply system 1.
- the current detector 2 detects the current IL flowing between the node N1 and the load 8, and outputs a signal ⁇ IL indicating the detected value to the control device 5.
- the uninterruptible power supplies U1-UN and the control device 5 are also connected to each other by a communication line 3.
- the uninterruptible power supplies U1-UN and the control device 5 exchange various signals and information via the communication line 3.
- the operation unit 4 includes a number of buttons, a number of switches, and an image display unit. By operating the operation unit 4, a user of the uninterruptible power supply system can operate the uninterruptible power supply system 1 automatically or can operate each uninterruptible power supply device U manually.
- the operation unit 4 outputs signals and information indicating the content of operations performed by the user to the control device 5.
- the control device 5 controls the entire uninterruptible power supply system 1 based on signals and information from the operation unit 4 and the uninterruptible power supplies U1 to UN, the output signal ⁇ IL of the current detector 2, etc. In particular, the control device 5 determines the shared current Is of each uninterruptible power supply U based on the load current IL indicated by the output signal ⁇ IL of the current detector 2. A signal indicating the shared current Is is provided to each uninterruptible power supply U via the communication line 3.
- each uninterruptible power supply device U supplies AC power from the bypass AC power supply 6 to the load 8, and converts AC power from the AC power supply 7 to DC power to charge the corresponding battery B.
- each uninterruptible power supply device U executes the battery power supply mode. At this time, each uninterruptible power supply device U converts the DC power of the corresponding battery B into AC power and supplies the shared current Is determined by the control device 5 to the load 8.
- FIG. 2 is a block diagram showing the configuration of the control device 5.
- the control device 5 includes a communication unit 11, a calculation unit 12, a control unit 13, and a notification unit 14.
- the communication unit 11 is provided between the control unit 13 and the communication line 3, and transmits and receives various signals and information between the control unit 13 and each uninterruptible power supply device U.
- the control unit 13 detects the number n of operable uninterruptible power supplies U based on signals from the operation unit 4 and the uninterruptible power supplies U, and provides a signal indicating the number n to the calculation unit 12.
- n is an integer greater than or equal to 1 and less than or equal to N.
- the control unit 13 outputs a signal ⁇ Is indicating the shared current Is to each uninterruptible power supply U via the communication unit 11 and the communication line 3.
- the control unit 13 also outputs various signals and information to each uninterruptible power supply U via the communication unit 11 and the communication line 3 in accordance with the output signal of the operation unit 4.
- the control unit 13 also provides a failure detection signal provided from the failed uninterruptible power supply U via the communication line 3 and the communication unit 11 to the notification unit 14.
- the notification unit 14 notifies the user of the uninterruptible power supply system that a part of the uninterruptible power supply U has failed using sound, light, images, etc. The user then repairs the failed uninterruptible power supply U or replaces it with a new one.
- FIG. 3 is a circuit block diagram showing the configuration of the uninterruptible power supply U1.
- the uninterruptible power supply U1 includes a bypass switch 20, a reactor 21, a bypass module 22, and M power modules P1 to PM, where M is an integer equal to or greater than 2.
- the power modules P1 to PM may be collectively and representatively referred to as a power module P.
- the M power modules P1 to PM form one embodiment of a "power converter.”
- Each of the other uninterruptible power supplies U2 to UN has a similar configuration to the uninterruptible power supply U1.
- the bypass switch 20 is a mechanical switch, and is connected between the bypass terminal T1 and the output terminal T4.
- the bypass switch 20 is turned on by the control device 5 when the operation unit 4 is operated to select the bypass power supply mode.
- the N bypass switches 20 included in the N uninterruptible power supplies U1 to UN are turned on, and a load current IL is supplied from the bypass AC power supply 6 to the load 8 via the parallel connection of the N bypass switches 20.
- the capacity of the bypass switches 20 is sufficiently large, so that a current of 1/N of the load current IL flows through each bypass switch 20.
- the reactor 21 is connected between the bypass terminal T1 and one terminal 22a of the bypass module 22.
- the other terminal 22b of the bypass module 22 is connected to the output terminal T4.
- the reactor 21 may be connected between the other terminal 22b of the bypass module 22 and the output terminal T4. In this case, the one terminal 22a of the bypass module 22 is directly connected to the bypass terminal T1.
- FIG. 4 is a circuit block diagram showing the configuration of the bypass module 22.
- the bypass module 22 includes a semiconductor switch 23, a power outage detection unit 26, a communication unit 27, a control unit 28, and a memory unit 29.
- the semiconductor switch 23 includes a pair of thyristors 24, 25 connected in antiparallel to each other.
- the anode and cathode of the thyristor 24 are connected to the terminals 22a and 22b, respectively, of the bypass module 22.
- the anode and cathode of the thyristor 25 are connected to the terminals 22b and 22a, respectively, of the bypass module 22.
- the semiconductor switch 23 may be composed of semiconductor elements other than the thyristors 24 and 25 (e.g., transistors, diodes, etc.).
- the semiconductor switch 23 is controlled by the control unit 28 and is turned on in the bypass ECO power supply mode. When the semiconductor switch 23 is turned on, AC power is supplied from the bypass AC power supply 6 to the load 8 via the reactor 21 and the semiconductor switch 23.
- N semiconductor switches 23 are turned on, and a load current IL is supplied from the bypass AC power supply 6 to the load 8 via a series connection of N reactors 21 and semiconductor switches 23.
- the reactor 21 is provided to reduce the variation in the magnitude of the current flowing through the N semiconductor switches 23 at this time. This will be described later.
- the semiconductor switch 23 is turned off, and the bypass AC power supply 6 is instantly disconnected from the load 8.
- the power outage detection unit 26 detects the instantaneous value of the AC voltage VI (i.e., the AC voltage VI supplied from the bypass AC power supply 6) that appears at the bypass terminal T1, determines whether or not a power outage has occurred in the bypass AC power supply 6 based on the detected value, and outputs a power outage detection signal ⁇ 26 that indicates the determination result.
- the instantaneous value of the AC voltage VI i.e., the AC voltage VI supplied from the bypass AC power supply 6
- the power outage detection unit 26 determines that the AC voltage VI is being supplied normally from the bypass AC power supply 6 and that the bypass AC power supply 6 is healthy.
- the power outage detection unit 26 determines that the AC voltage VI is not being supplied normally from the bypass AC power supply 6 and that a power outage of the bypass AC power supply 6 has occurred.
- the power outage detection signal ⁇ 26 When the bypass AC power supply 6 is healthy, the power outage detection signal ⁇ 26 is set to the inactive "H” level. When a power outage occurs in the bypass AC power supply 6, the power outage detection signal ⁇ 26 is set to the active "L” level.
- the communication unit 27 is connected to the power modules P1-PM in the uninterruptible power supply U1, the other uninterruptible power supplies U2-UM, and the control device 5 via the communication line 3, and transmits and receives various signals and information between them and the control unit 28.
- the control unit 28 turns on the semiconductor switch 23 when the control device 5 issues a command to execute the bypass ECO power supply mode via the communication line 3 and the communication unit 27, and the power failure detection signal ⁇ 26 is at the inactivation level of "H".
- the control unit 28 turns off the semiconductor switch 23.
- the power failure detection signal ⁇ 26 is provided to the power modules P1 to PM via the control unit 28, the communication unit 27, and the communication line 3.
- the control unit 28 also selects the number m of power modules P required to efficiently supply the shared current Is indicated by the signal ⁇ Is provided from the control device 5 (FIG. 5) via the communication line 3 and the communication unit 27, and outputs signals SE1 to SEM indicating the selection result.
- m is an integer greater than or equal to 1 and less than or equal to M.
- the selection signals SE1 to SEM may be collectively referred to as the selection signal SE.
- the reason for selecting m power modules P is that if all power modules P1 to PM were selected, the output current of each power module P would be too small, reducing the efficiency of each power module P.
- the selection signals SE1 to SEM correspond to the power modules P1 to PM, respectively.
- the selection signal SE corresponding to that power module P is set to the selection level "H”.
- the selection signal SE corresponding to that power module P is set to the non-selection level "L”.
- the control unit 28 calculates a sub-shared current Iss that is 1/m of the shared current Is, and provides a signal ⁇ Iss indicating the sub-shared current Iss to each power module P. In the event of a power outage in the bypass AC power supply 6, each of the selected m power modules P supplies a sub-shared current Iss that is 1/m of the shared current Is to the load 8.
- control unit 28 changes the combination of the m power modules P to be selected each time a power outage occurs in the bypass AC power supply 6. This is to prevent a specific power module P from being repeatedly selected and deteriorating faster than other power modules P.
- the memory unit 29 stores a table showing the combinations of the m power modules P.
- FIG. 5 is a diagram showing a table stored in the memory unit 29.
- 10 patterns are shown. In each pattern, the power module P marked with a circle is selected.
- power modules P1 to P3 are selected out of the five power modules P1 to P5.
- power modules P1, P2, and P4 are selected.
- power modules P1, P2, and P5 are selected.
- power modules P1, P3, and P4 are selected.
- power modules P1, P3, and P5 are selected.
- power modules P1, P4, and P5 are selected.
- power modules P2 to P4 are selected.
- power modules P2, P3, and P5 are selected.
- power modules P2, P4, and P5 are selected.
- power modules P3 to P5 are selected.
- the control unit 28 selects three power modules P1 to P3 of pattern 1 the first time, selects three power modules P of patterns 2 to 10 the second to tenth times, and again selects three power modules P1 to P3 of pattern 1 the eleventh time. This is the same as above.
- the control unit 28 selects one of the four tables according to the value of m, and refers to that table to select m power modules P.
- each power module P includes an input terminal T5, a DC terminal T6, and an output terminal T7.
- the input terminal T5, DC terminal T6, and output terminal T7 are connected to the input terminal T2, DC terminal T3, and output terminal T4 of the corresponding uninterruptible power supply U1, respectively.
- the power module P converts the AC power supplied from the AC power source 7 into DC power and stores it in the corresponding battery B1.
- the power module P stops charging the battery B1.
- each power module P When the power failure detection signal ⁇ 26 (FIG. 4) is at the inactive "H" level during bypass ECO power supply mode, each power module P outputs a counter voltage VC that opposes the AC voltage VO appearing at the output terminal T4, and is placed in a standby state in which no current is exchanged with other power modules P or the load 8. In other words, at this time, each power module P outputs the counter voltage VC and outputs 0 A.
- each of the m power modules P selected by the control unit 28 (FIG. 4) from among the power modules P1 to PM supplies the sub-shared current Iss indicated by the signal ⁇ Iss from the control unit 28 to the load 8.
- FIG. 6 is a circuit block diagram showing the configuration of power module P1.
- this power module P1 in addition to terminals T5 to T7 (FIG. 3), this power module P1 includes fuses F1 to F3, switches S1 to S3, capacitors C1 to C3, reactors L1 to L3, converter 31, DC line DL, inverter 32, bidirectional chopper 33, current detectors CD1 to CD3, communication unit 34, control unit 35, and fault detection unit 36.
- Each of the other power modules P2 to PM has the same configuration as power module P1.
- One terminal of the switch S1 is connected to the input terminal T5 via the fuse F1, and the other terminal is connected to the input node of the converter 31 via the reactor L1.
- the capacitor C1 is connected to the other terminal of the switch S1.
- the output node of the converter 31 is connected to the input node of the inverter 32 via the DC line DL, and is also connected to one input/output node of the bidirectional chopper 33.
- the capacitor C3 is connected to the DC line DL.
- the DC lines DL of the power modules P1 to PN are connected to each other.
- the output node of the inverter 32 is connected to one terminal of a switch S2 via a reactor L2, and the other terminal of the switch S2 is connected to an output terminal T7 via a fuse F2.
- a capacitor C2 is connected to one terminal of the switch S2.
- One terminal of the switch S3 is connected to a DC terminal T6 via a fuse F3, and the other terminal is connected to the other input/output node of the bidirectional chopper 33 via a reactor L3.
- Fuse F1 is blown when an overcurrent flows, protecting converter 31 and other components.
- Switch S1 is controlled by control unit 35. When AC voltage Vi is being supplied normally from AC power supply 7 (when AC power supply 7 is functioning properly), switch S1 is turned on. When AC voltage Vi is not being supplied normally from AC power supply 7 (when AC power supply 7 is experiencing a power outage), switch S1 is turned off.
- Capacitor C1 and reactor L1 form an AC filter.
- the AC filter is a low-pass filter that passes commercial frequency AC power supplied from AC power source 7 and blocks the switching frequency signal generated by converter 31.
- the converter 31 is controlled by the control unit 35, and when the AC power supply 7 is healthy, it converts the AC power from the AC power supply 7 into DC power and supplies the DC power to the inverter 32 and the bidirectional chopper 33 via the DC line DL.
- the converter 31 outputs a DC current to the DC line DL so that the DC voltage VD of the DC line DL matches the target DC voltage VDT.
- the capacitor C1, the reactor L1, and the converter 31 constitute one embodiment of a "forward converter” that converts AC power into DC power.
- the capacitor C3 smoothes and stabilizes the DC voltage VD of the DC line DL.
- Fuse F3 is blown in the event of an overcurrent, protecting battery B1, bidirectional chopper 33, etc.
- Switch S3 is turned on when power module P1 is in use, and turned off, for example, during maintenance of battery B1.
- Reactor L3 is a low-pass filter that passes DC power and blocks the switching frequency signal generated by bidirectional chopper 33.
- the bidirectional chopper 33 is controlled by the control unit 35, and stores the DC power generated by the converter 31 in the battery B1 when the AC power supply 7 is healthy, and supplies the DC power of the battery B1 to the inverter 32 when the bypass AC power supply 6 fails.
- the bidirectional chopper 33 supplies a DC current to the battery B1 so that the terminal voltage VB of the battery B1 becomes the target DC voltage VBT.
- the bidirectional chopper 33 outputs a DC current to the DC line DL so that the DC voltage VD of the DC line DL becomes equal to the target DC voltage VDT.
- the inverter 32 is controlled by the control unit 35.
- the inverter 32 When the power failure detection signal ⁇ 26 (FIG. 4) is at the inactivation level "H", the inverter 32 outputs a counter voltage VC that opposes the AC voltage VO appearing at the output terminal T7, and is placed in a standby state in which it does not exchange current with the other power modules P2 to PM or the load 8. In other words, at this time the inverter 32 outputs the counter voltage VC and outputs 0 A.
- the reactor L2 and the capacitor C2 form an AC filter.
- the AC filter is a low-pass filter that passes commercial frequency AC power generated by the inverter 32 and blocks signals of the switching frequency generated by the inverter 32. In other words, the AC filter shapes the waveform of the output voltage of the inverter 32 into a sine wave.
- the inverter 32, the reactor L2, and the capacitor C2 form one embodiment of an "inverter" that converts DC power to AC power.
- the switch S2 is turned on when the power module P1 is used, and is turned off when the inverter 32 fails or during maintenance of the inverter 32.
- the AC voltage Vi at the input terminal T5 i.e., the AC voltage supplied from the AC power source 7
- the AC voltage VO at the output terminal T7 i.e., the output voltage
- the DC voltage VB at the DC terminal T6 i.e., the voltage between the terminals of the battery B1
- the DC voltage VD of the DC line DL are provided to the control unit 35.
- Current detector CD1 detects the instantaneous value of the AC current flowing through reactor L1 (i.e., the input current of converter 31) and provides a signal indicating the detected value to control unit 35.
- Current detector CD2 detects the instantaneous value of the AC current flowing through reactor L2 (i.e., the output current of inverter 32) and provides a signal indicating the detected value to control unit 35.
- Current detector CD3 detects the instantaneous value of the DC current flowing through reactor L3 (i.e., the DC current flowing through battery B1) and provides a signal indicating the detected value to control unit 35.
- the communication unit 34 is provided between the control unit 35 and the communication line 3, and transmits and receives various signals and information between the bypass module 22, the other power modules P2 to PM, and the control device 5.
- the fault detection unit 36 determines whether the corresponding inverter 32 is normal or not, and outputs a fault detection signal ⁇ 36 indicating the determination result. If the inverter 32 is normal, the fault detection signal ⁇ 36 is set to the inactivation level "L" level. If the inverter 32 is faulty, the fault detection signal ⁇ 36 is set to the activation level "H" level.
- the fault detection signal ⁇ 36 is given to the control unit 35.
- the control unit 35 controls the inverter 32.
- the control unit 35 stops the operation of the inverter 32 and turns off the switch S2.
- Failure detection signal ⁇ 36 is also provided to control unit 28 via control unit 35, communication unit 34, communication line 3, and communication unit 27 (FIG. 4).
- control unit 28 selects m power modules P from power modules P2 to PM other than the power module corresponding to that failure detection signal ⁇ 36 (P1 in this case).
- the control unit 35 controls the entire power module P1 based on the instantaneous values of the AC voltages Vi, VO, the instantaneous values of the DC voltages VB, VD, the detection values of the current detectors CD1 to CD3, the fault detection signal ⁇ 36, and various signals and information supplied from the control device 5 and the control unit 28 via the communication line 3 and the communication unit 34.
- control unit 35 controls the converter 31 based on the instantaneous value of the AC voltage Vi, the instantaneous value of the DC voltage VD of the DC line DL, the detection value of the current detector CD1, etc. As a result, the DC voltage VD of the DC line DL is maintained at the target DC voltage VDT.
- the control unit 35 also controls the bidirectional chopper 33 based on the instantaneous value of the AC voltage Vi, the instantaneous value of the DC voltage VD of the DC line DL, the instantaneous value of the DC voltage VB, the output signal of the current detector CD3, etc. This maintains the inter-terminal voltage VB of the battery B1 at the target DC voltage VBT.
- the control unit 35 also controls the inverter 32 based on the instantaneous value of the AC voltage VO, the output signal of the current detector CD2, the power failure detection signal ⁇ 26, the signal ⁇ Iss, the fault detection signal ⁇ 36, etc. This maintains the output current of the inverter 32 at the secondary current Iss or 0 A.
- FIG. 7 is a block diagram showing the configuration of the portion of the control unit 35 that is related to the control of the inverter 32.
- the control unit 35 includes a current command unit 41, a voltage control unit 42, a current control unit 43, and a PWM (Pulse Width Modulation) control unit 44.
- PWM Pulse Width Modulation
- the current command unit 41 generates a current command value Ic1 based on the power failure detection signal ⁇ 26, the selection signal SE1, and the signal ⁇ Iss provided by the bypass module 22 (FIG. 4).
- the selection signal SE1 is at the "L" level, which is the non-selection level, the current command value Ic1 is set to a value corresponding to 0 A, regardless of the power failure detection signal ⁇ 26.
- the current command value Ic1 is set to a value corresponding to 0 A.
- the current command value Ic1 is set to a value according to the sub-shared current Iss indicated by the signal ⁇ Iss.
- the voltage control unit 42 finds the deviation between the current command value Ic1 from the current command unit 41 and the detection value Io1 of the current detector CD2 (the output current of the power module U1), and generates a voltage command value Vc so that the deviation is eliminated.
- the current control unit 43 finds the deviation between the output voltage VO and the voltage command value Vc, and generates a current command value Ic so that the deviation is eliminated.
- the PWM control unit 44 When the fault detection signal ⁇ 36 is at the inactivation level "L”, the PWM control unit 44 operates in synchronization with the AC voltage VO at the output terminal T7, generates a PWM signal according to the current command value Ic, and controls the inverter 32 with the PWM signal. When the fault detection signal ⁇ 36 is at the activation level "H”, the PWM control unit 44 stops the operation of the inverter 32.
- the inverter 32 when the bypass AC power supply 6 is healthy, the inverter 32 outputs a counter voltage VC whose value corresponds to the output voltage VO of the other power modules P2 to PM, outputs 0 A, and is in a standby state in which no current is exchanged with the other power modules P2 to PM or the load 8.
- the inverter 32 When the corresponding selection signal SE1 is at the "H" level, which is the selection level, if a power outage occurs in the bypass AC power supply 6, the inverter 32 outputs the secondary shared current Iss. At this time, the inverter 32 has already been started and is in a standby state, so when the current command value Ic1 is increased, the output current of the inverter 32 increases quickly and smoothly.
- the bypass AC power supply 6 When the corresponding selection signal SE1 is at the non-selection level "L", the bypass AC power supply 6 outputs 0 A and is maintained in standby mode regardless of whether it is healthy or not.
- each power module P (FIG. 6) of each uninterruptible power supply U, the battery B is charged by the converter 31 and bidirectional chopper 33.
- the inverter 32 is controlled by the control unit 35 (FIGS. 6 and 7) and is placed in a standby state in which it outputs the counter voltage VC without outputting any current.
- the load current IL is detected by the current detector 2 ( Figure 1), and the control device 5 ( Figure 2) calculates the shared current Is of each uninterruptible power supply U based on the detected value, and a signal ⁇ Is indicating the shared current Is is sent to the control unit 28 ( Figure 4) of each uninterruptible power supply U.
- the control unit 28 selects the number m of power modules P required to efficiently supply the shared current Is indicated by the signal ⁇ Is, and determines the sub-shared current Iss that the selected power modules P should supply to the load 8.
- the N semiconductor switches 23 are turned off, and the bypass AC power supply 6 is instantly disconnected from the load 8.
- the sub-shared current Iss is supplied to the load 8 from each of the selected m power modules P of each uninterruptible power supply U, and the operation of the load 8 continues.
- the N semiconductor switches 23 included in the N uninterruptible power supplies U1 to UN (Fig. 1) are turned on, and in each uninterruptible power supply U, AC power is supplied from the bypass AC power supply 6 to the load 8 via the reactor 21 and semiconductor switch 23, and each power module P is returned to a standby state.
- FIG. 8 is a circuit block diagram showing the main parts of an uninterruptible power supply system that is a comparative example of this embodiment, and is a diagram to be compared with FIG. 4.
- the comparative example differs from this embodiment in that the reactor 21 is removed, and one terminal of the semiconductor switch 23 is directly connected to the bypass terminal T1.
- FIG. 9 is a circuit block diagram for explaining the bypass ECO power supply mode of an uninterruptible power supply system serving as a comparative example.
- N semiconductor switches 23 are turned on, and a current IL is supplied from the bypass AC power supply 6 to the load 8 via the parallel connection of N semiconductor switches 23.
- the sum of I1 to IN is IL.
- the threshold voltages Vt of the N semiconductor switches 23 are the same, the load current IL is evenly distributed to the N semiconductor switches 23, and a current IL/N that is 1/N of the load current IL flows through each semiconductor switch 23.
- the threshold voltages Vt of the N semiconductor switches 23 vary within a range of about 10 to 30% from the rated value Vtc. For this reason, the values of the currents I1 to IN flowing through the N semiconductor switches 23 in the bypass ECO power supply mode do not become a constant value IL/N, but vary over a large range.
- FIG. 10 is a diagram illustrating the VI characteristics of semiconductor switches 23 in a comparative example.
- curve A shows the VI characteristics of a semiconductor switch 23 having a rated threshold voltage Vtc.
- Curve B shows the VI characteristics of a semiconductor switch 23 having the smallest threshold voltage Vt1 among the N semiconductor switches 23.
- Curve C shows the VI characteristics of a semiconductor switch 23 having the largest threshold voltage Vt2 among the N semiconductor switches 23.
- FIG. 11 is a circuit block diagram for explaining the bypass ECO power supply mode of the uninterruptible power supply system according to this embodiment.
- N semiconductor switches 23 included in N uninterruptible power supplies U1 to UN are turned on, and AC power is supplied from the bypass AC power source 6 to the load 8 via the parallel connection of the N uninterruptible power supplies U1 to UN.
- each uninterruptible power supply U includes a series connection of a reactor 21 and a semiconductor switch 23.
- FIG. 12 is a diagram illustrating the V-I characteristics of reactor 21.
- the current I flowing through reactor 21 increases in proportion to the voltage V.
- Reactor 21 is an electric wire wound into a coil, and the impedance of each reactor 21 is adjustable.
- the threshold voltage Vt of semiconductor switch 23 cannot be adjusted after semiconductor switch 23 is manufactured. For this reason, the characteristic variation of reactor 21 is sufficiently small compared to the variation of threshold voltage Vt of semiconductor switch 23.
- FIG. 13 is a diagram illustrating the VI characteristics of a series connection of reactor 21 and semiconductor switch 23 in this embodiment. Curves D, E, and F are obtained by adding the VI characteristics of reactor 21 to curves A, B, and C, respectively.
- each uninterruptible power supply U includes a reactor 21 and a semiconductor switch 23 connected in series between the bypass AC power supply 6 and the load 8, so that when each semiconductor switch 23 is turned on, the load current IL is shunted to a series connection of N reactors 21 and semiconductor switches 23. Therefore, compared to a case where there is no reactor 21, the variation in the magnitude of the currents I1 to IN flowing through the N semiconductor switches 23 can be suppressed to a small value, and the semiconductor switches 23 can be made smaller and less expensive.
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Abstract
In this uninterruptible power supply system (1), each uninterruptible power supply device (U) includes a reactor (21) and a semiconductor switch (23) which are connected in series between a bypass AC power supply (6) and a load (8). When turning on each semiconductor switch, load current (IL) is shunted to the series connection bodies of the N reactors and semiconductor switches. Accordingly, in comparison with a case without the reactors, it is possible to suppress and reduce variation in the magnitudes of currents (I1 to IN) flowing through the N semiconductor switches, thereby enabling reduction in the size of the semiconductor switch and reduction in cost.
Description
本開示は、無停電電源システムに関し、特に、負荷に対して並列接続される複数の無停電電源装置を備えた無停電電源システムに関する。
This disclosure relates to an uninterruptible power supply system, and in particular to an uninterruptible power supply system having multiple uninterruptible power supply devices connected in parallel to a load.
たとえば国際公開2017-009998号(特許文献1)には、交流電源と負荷の間に並列接続されるバイパススイッチ、小型半導体スイッチ、および電力変換器を備えた無停電電源装置が開示されている。電力変換器は、交流電源から供給される交流電力を直流電力に変換するコンバータと、直流電力を交流電力に変換して負荷に供給するインバータとを含む。
For example, International Publication No. 2017-009998 (Patent Document 1) discloses an uninterruptible power supply including a bypass switch, a small semiconductor switch, and a power converter connected in parallel between an AC power source and a load. The power converter includes a converter that converts AC power supplied from the AC power source into DC power, and an inverter that converts the DC power into AC power and supplies it to the load.
交流電源の健全時には、インバータ給電モードが実行され、バイパススイッチおよび半導体スイッチがオフされる。また、コンバータは、交流電源からの交流電力を直流電力に変換する。この直流電力は、バッテリに蓄えられるとともにインバータに与えられる。インバータは、直流電力を交流電力に変換して負荷に供給する。
When the AC power supply is healthy, the inverter power supply mode is executed and the bypass switch and semiconductor switch are turned off. The converter also converts AC power from the AC power supply into DC power. This DC power is stored in the battery and is also provided to the inverter. The inverter converts the DC power into AC power and supplies it to the load.
インバータが故障した場合には、バイパス給電モードが実行され、電力変換器の運転が停止されるとともに、バイパススイッチおよび半導体スイッチがオンされる。電流による半導体スイッチの過熱を防止するため、半導体スイッチは所定時間経過後にオフされる。交流電源からバイパススイッチを介して負荷に交流電力が供給される。
If the inverter fails, the bypass power supply mode is executed, the operation of the power converter is stopped, and the bypass switch and semiconductor switch are turned on. To prevent the semiconductor switch from overheating due to current, the semiconductor switch is turned off after a specified time has elapsed. AC power is supplied to the load from the AC power source via the bypass switch.
交流電源の停電が発生した場合には、バッテリ給電モードが実行され、コンバータの運転が停止されるとともに、インバータは、バッテリの直流電力を交流電力に変換して負荷に供給する。したがって、交流電源の停電が発生した場合でも、バッテリに直流電力が蓄えられている期間は、負荷の運転を継続することができる。
If a power outage occurs in the AC power supply, the battery power supply mode is activated, the converter operation is stopped, and the inverter converts the DC power of the battery into AC power and supplies it to the load. Therefore, even if a power outage occurs in the AC power supply, the load can continue to operate as long as DC power is stored in the battery.
しかし、このような無停電電源装置では、主に電力変換器で損失が発生し、効率が90~96%程度と低いという問題がある。この対策として、バイパスECO給電モードを有する無停電電源装置が注目されている。この無停電電源装置は、交流電源と負荷の間に並列接続される大型半導体スイッチおよび電力変換器を備える。
However, such uninterruptible power supplies have the problem that losses occur mainly in the power converter, resulting in low efficiency of around 90-96%. As a solution to this problem, uninterruptible power supplies with a bypass ECO power supply mode have attracted attention. These uninterruptible power supplies are equipped with a large semiconductor switch and a power converter that are connected in parallel between the AC power supply and the load.
交流電源の健全時には、バイパスECO給電モードが実行され、半導体スイッチがオンされ、交流電源からの交流電力が半導体スイッチを介して負荷に供給される。交流電源の停電が発生した場合には、バッテリ給電モードが実行され、半導体スイッチがオフされ、電力変換器に含まれるインバータがバッテリの直流電力を交流電力に変換して負荷に供給する。この無停電電源装置では、主に半導体スイッチで損失が発生するが、半導体スイッチの損失は電力変換器の損失よりも小さいので、99%と高い効率が得られる。
When the AC power supply is healthy, the bypass ECO power supply mode is executed, the semiconductor switch is turned on, and AC power from the AC power supply is supplied to the load via the semiconductor switch. In the event of a power outage in the AC power supply, the battery power supply mode is executed, the semiconductor switch is turned off, and the inverter included in the power converter converts the battery's DC power to AC power and supplies it to the load. In this uninterruptible power supply, losses occur mainly in the semiconductor switch, but because the losses in the semiconductor switch are smaller than the losses in the power converter, a high efficiency of 99% can be achieved.
また、交流電源と負荷の間に複数の無停電電源装置を並列接続することにより、大容量の負荷を運転することが可能となる。各無停電電源装置がバイパスECO給電モードを実行する場合、交流電源と負荷の間に複数の半導体スイッチが並列接続されることとなり、負荷電流が複数の半導体スイッチに分流される。
In addition, by connecting multiple uninterruptible power supplies in parallel between the AC power supply and the load, it becomes possible to operate a large-capacity load. When each uninterruptible power supply operates in the bypass ECO power supply mode, multiple semiconductor switches are connected in parallel between the AC power supply and the load, and the load current is divided among the multiple semiconductor switches.
この場合、複数の半導体スイッチのしきい値電圧のばらつきに起因して複数の半導体スイッチに流れる電流の大きさがばらつき、しきい値電圧が小さな半導体スイッチに大きな電流が流れる恐れがある。このため、大電流を安定に流すことが可能な大型で高価格の半導体スイッチを使用する必要があり、システムの大型化、コスト高を招くという問題がある。
In this case, there is a risk that the magnitude of the current flowing through the multiple semiconductor switches will vary due to variations in the threshold voltages of the multiple semiconductor switches, causing a large current to flow through a semiconductor switch with a small threshold voltage. This necessitates the use of large, expensive semiconductor switches that are capable of stably passing a large current, resulting in problems such as an increase in the size of the system and increased costs.
それゆえに、本開示の主たる目的は、半導体スイッチの小型化、低コスト化を図ることが可能な無停電電源システムを提供することである。
Therefore, the primary objective of this disclosure is to provide an uninterruptible power supply system that enables miniaturization and cost reduction of semiconductor switches.
本開示の無停電電源システムは、負荷に対して並列接続される複数の無停電電源装置を備えたものである。各無停電電源装置は、第1の交流電源の健全時にオンにされ、第1の交流電源の停電時にオフされる半導体スイッチと、第1の交流電源と負荷の間に半導体スイッチと直列接続されるリアクトルと、第1の交流電源の停電時に、直流電源から供給される直流電力を交流電力に変換して負荷に供給する電力変換器とを含む。
The uninterruptible power supply system disclosed herein includes a plurality of uninterruptible power supply devices connected in parallel to a load. Each uninterruptible power supply device includes a semiconductor switch that is turned on when the first AC power supply is healthy and turned off when the first AC power supply is interrupted, a reactor that is connected in series with the semiconductor switch between the first AC power supply and the load, and a power converter that converts DC power supplied from a DC power supply into AC power and supplies it to the load when the first AC power supply is interrupted.
本開示の無停電電源システムでは、複数の無停電電源装置の各々が第1の交流電源と負荷の間に直列接続される半導体スイッチおよびリアクトルを含むので、各半導体スイッチをオンすると、負荷電流は複数の半導体スイッチおよびリアクトルの直列接続体に分流される。したがって、リアクトルがない場合に比べ、複数の半導体スイッチに流れる電流の大きさのばらつきを小さく抑制することができ、半導体スイッチの小型化、低コスト化を図ることができる。
In the uninterruptible power supply system disclosed herein, each of the multiple uninterruptible power supply devices includes a semiconductor switch and a reactor connected in series between the first AC power supply and the load, so that when each semiconductor switch is turned on, the load current is diverted to the series connection of the multiple semiconductor switches and reactors. Therefore, compared to a case where there is no reactor, the variation in the magnitude of the current flowing through the multiple semiconductor switches can be reduced, and the semiconductor switches can be made smaller and less expensive.
図1は、本開示の一実施の形態に従う無停電電源システム1の構成を示す回路ブロック図である。図1において、この無停電電源システム1は、N台の無停電電源装置(UPS)U1~UN、N個のバッテリB1~BN、電流検出器2、通信線3、操作部4、および制御装置5を備える。Nは、2以上の整数である。無停電電源装置U1~UNを総称して代表的に無停電電源装置Uと称する場合がある。また、バッテリB1~BNを総称して代表的にバッテリBと称する場合がある。
FIG. 1 is a circuit block diagram showing the configuration of an uninterruptible power supply system 1 according to one embodiment of the present disclosure. In FIG. 1, the uninterruptible power supply system 1 comprises N uninterruptible power supplies (UPS) U1-UN, N batteries B1-BN, a current detector 2, a communication line 3, an operation unit 4, and a control device 5. N is an integer equal to or greater than 2. The uninterruptible power supplies U1-UN may be collectively and representatively referred to as uninterruptible power supply U. Furthermore, the batteries B1-BN may be collectively and representatively referred to as battery B.
各無停電電源装置Uは、バイパス端子T1、入力端子T2、直流端子T3、および出力端子T4を含む。バイパス端子T1は、バイパス交流電源6(第1の交流電源)に接続される。入力端子T2は、交流電源7(第2の交流電源)に接続される。バイパス交流電源6と交流電源7は、別々に設けられていてもよいし、同じものでも構わない。交流電源6,7の各々は、商用交流電源でもよいし、発電機でもよい。交流電源6,7の各々は、無停電電源装置U1~UNに交流電力を供給する。
Each uninterruptible power supply U includes a bypass terminal T1, an input terminal T2, a DC terminal T3, and an output terminal T4. The bypass terminal T1 is connected to a bypass AC power supply 6 (first AC power supply). The input terminal T2 is connected to an AC power supply 7 (second AC power supply). The bypass AC power supply 6 and the AC power supply 7 may be provided separately or may be the same. Each of the AC power supplies 6, 7 may be a commercial AC power supply or a generator. Each of the AC power supplies 6, 7 supplies AC power to the uninterruptible power supplies U1 to UN.
無停電電源装置U1~UNの直流端子T3は、それぞれバッテリB1~BN(電力貯蔵装置)に接続される。バッテリB1~BNの各々は、直流電力を蓄える。バッテリB1~BNの代わりに1つの大型バッテリが設けられ、無停電電源装置U1~UNの直流端子T3が1つの大型バッテリに接続されていても構わない。また、バッテリBの代わりにコンデンサが設けられていても構わない。
The DC terminals T3 of the uninterruptible power supplies U1 to UN are connected to batteries B1 to BN (power storage devices), respectively. Each of the batteries B1 to BN stores DC power. A single large battery may be provided in place of the batteries B1 to BN, and the DC terminals T3 of the uninterruptible power supplies U1 to UN may be connected to the single large battery. Also, a capacitor may be provided in place of the battery B.
無停電電源装置U1~UNの出力端子T4は、ともにノードN1に接続され、ノードN1は負荷8に接続される。負荷8は、無停電電源システム1から供給される交流電力によって駆動される。
The output terminals T4 of the uninterruptible power supplies U1 to UN are all connected to a node N1, which is connected to a load 8. The load 8 is driven by AC power supplied from the uninterruptible power supply system 1.
電流検出器2は、ノードN1と負荷8の間に流れる電流ILを検出し、検出値を示す信号φILを制御装置5に出力する。また、無停電電源装置U1~UNおよび制御装置5は、通信線3によって互いに接続されている。無停電電源装置U1~UNおよび制御装置5は、通信線3を介して種々の信号および情報を授受する。
The current detector 2 detects the current IL flowing between the node N1 and the load 8, and outputs a signal φIL indicating the detected value to the control device 5. The uninterruptible power supplies U1-UN and the control device 5 are also connected to each other by a communication line 3. The uninterruptible power supplies U1-UN and the control device 5 exchange various signals and information via the communication line 3.
操作部4は、複数のボタン、複数のスイッチ、画像表示部を含む。無停電電源システムの使用者は、操作部4を操作することにより、無停電電源システム1を自動運転させたり、各無停電電源装置Uを手動で動作させることができる。操作部4は、使用者によって操作された内容を示す信号および情報を制御装置5に出力する。
The operation unit 4 includes a number of buttons, a number of switches, and an image display unit. By operating the operation unit 4, a user of the uninterruptible power supply system can operate the uninterruptible power supply system 1 automatically or can operate each uninterruptible power supply device U manually. The operation unit 4 outputs signals and information indicating the content of operations performed by the user to the control device 5.
制御装置5は、操作部4および無停電電源装置U1~UNからの信号および情報、電流検出器2の出力信号φIL等に基づいて、無停電電源システム1全体を制御する。特に、制御装置5は、電流検出器2の出力信号φILによって示される負荷電流IL基づいて、各無停電電源装置Uの分担電流Isを求める。分担電流Isを示す信号は、通信線3を介して各無停電電源装置Uに与えられる。
The control device 5 controls the entire uninterruptible power supply system 1 based on signals and information from the operation unit 4 and the uninterruptible power supplies U1 to UN, the output signal φIL of the current detector 2, etc. In particular, the control device 5 determines the shared current Is of each uninterruptible power supply U based on the load current IL indicated by the output signal φIL of the current detector 2. A signal indicating the shared current Is is provided to each uninterruptible power supply U via the communication line 3.
操作部4を用いてシステム1の自動運転が指示された場合において、バイパス交流電源6の健全時には、各無停電電源装置UにおいてバイパスECO給電モードが実行される。このとき各無停電電源装置Uは、バイパス交流電源6からの交流電力を負荷8に供給するとともに、交流電源7からの交流電力を直流電力に変換して対応するバッテリBを充電する。
When automatic operation of the system 1 is instructed using the operation unit 4, and the bypass AC power supply 6 is healthy, the bypass ECO power supply mode is executed in each uninterruptible power supply device U. At this time, each uninterruptible power supply device U supplies AC power from the bypass AC power supply 6 to the load 8, and converts AC power from the AC power supply 7 to DC power to charge the corresponding battery B.
バイパスECO給電モードの実行中にバイパス交流電源6の停電が発生した場合には、各無停電電源装置Uはバッテリ給電モードを実行する。このとき各無停電電源装置Uは、対応するバッテリBの直流電力を交流電力に変換し、制御装置5によって求められる分担電流Isを負荷8に供給する。
If a power outage occurs in the bypass AC power supply 6 while the bypass ECO power supply mode is being executed, each uninterruptible power supply device U executes the battery power supply mode. At this time, each uninterruptible power supply device U converts the DC power of the corresponding battery B into AC power and supplies the shared current Is determined by the control device 5 to the load 8.
図2は、制御装置5の構成を示すブロック図である。図2において、制御装置5は、通信部11、演算部12、制御部13、および報知部14を含む。通信部11は、制御部13と通信線3の間に設けられ、制御部13と各無停電電源装置Uの間で種々の信号および情報を授受する。
FIG. 2 is a block diagram showing the configuration of the control device 5. In FIG. 2, the control device 5 includes a communication unit 11, a calculation unit 12, a control unit 13, and a notification unit 14. The communication unit 11 is provided between the control unit 13 and the communication line 3, and transmits and receives various signals and information between the control unit 13 and each uninterruptible power supply device U.
制御部13は、操作部4および無停電電源装置Uからの信号に基づいて、運転可能な無停電電源装置Uの台数nを検出し、その台数nを示す信号を演算部12に与える。nは、1以上でN以下の整数である。
The control unit 13 detects the number n of operable uninterruptible power supplies U based on signals from the operation unit 4 and the uninterruptible power supplies U, and provides a signal indicating the number n to the calculation unit 12. n is an integer greater than or equal to 1 and less than or equal to N.
演算部12は、電流検出器2の出力信号φILによって示される負荷電流ILと、制御部13からの信号によって示される無停電電源装置Uの台数nとに基づいて、各無停電電源装置Uがバッテリ給電モード時に負荷8に供給すべき分担電流Isを求め、分担電流Isを示す信号を制御部13に与える。たとえば、Is=IL/nである。
The calculation unit 12 calculates the shared current Is that each uninterruptible power supply U should supply to the load 8 in battery power supply mode based on the load current IL indicated by the output signal φIL of the current detector 2 and the number n of uninterruptible power supplies U indicated by a signal from the control unit 13, and provides a signal indicating the shared current Is to the control unit 13. For example, Is = IL/n.
制御部13は、分担電流Isを示す信号φIsを通信部11および通信線3を介して各無停電電源装置Uに出力する。また、制御部13は、操作部4の出力信号に従って、種々の信号および情報を通信部11および通信線3を介して各無停電電源装置Uに出力する。
The control unit 13 outputs a signal φIs indicating the shared current Is to each uninterruptible power supply U via the communication unit 11 and the communication line 3. The control unit 13 also outputs various signals and information to each uninterruptible power supply U via the communication unit 11 and the communication line 3 in accordance with the output signal of the operation unit 4.
また、制御部13は、故障した無停電電源装置Uから通信線3および通信部11を介して与えられる故障検出信号を報知部14に与える。報知部14は、無停電電源装置Uの一部が故障した旨を音、光、画像などを使用して無停電電源システムの使用者に報知する。使用者は、故障した無停電電源装置Uを修理するか、新品と交換する。
The control unit 13 also provides a failure detection signal provided from the failed uninterruptible power supply U via the communication line 3 and the communication unit 11 to the notification unit 14. The notification unit 14 notifies the user of the uninterruptible power supply system that a part of the uninterruptible power supply U has failed using sound, light, images, etc. The user then repairs the failed uninterruptible power supply U or replaces it with a new one.
図3は、無停電電源装置U1の構成を示す回路ブロック図である。図3において、無停電電源装置U1は、バイパススイッチ20、リアクトル21、バイパスモジュール22、およびM個のパワーモジュールP1~PMを含む。Mは、2以上の整数である。パワーモジュールP1~PMを総称して代表的にパワーモジュールPと称する場合がある。M個のパワーモジュールP1~PMは、「電力変換器」の一実施例を構成する。他の無停電電源装置U2~UNの各々は、無停電電源装置U1と同様の構成である。
FIG. 3 is a circuit block diagram showing the configuration of the uninterruptible power supply U1. In FIG. 3, the uninterruptible power supply U1 includes a bypass switch 20, a reactor 21, a bypass module 22, and M power modules P1 to PM, where M is an integer equal to or greater than 2. The power modules P1 to PM may be collectively and representatively referred to as a power module P. The M power modules P1 to PM form one embodiment of a "power converter." Each of the other uninterruptible power supplies U2 to UN has a similar configuration to the uninterruptible power supply U1.
バイパススイッチ20は、機械スイッチであり、バイパス端子T1および出力端子T4間に接続される。バイパススイッチ20は、操作部4が操作されてバイパス給電モードが選択された場合に、制御装置5によってオンされる。バイパス給電モード時には、N個の無停電電源装置U1~UNに含まれるN個のバイパススイッチ20がオンされ、バイパス交流電源6からN個のバイパススイッチ20の並列接続体を介して負荷8に負荷電流ILが供給される。このとき、バイパススイッチ20の容量は十分に大きいので、各バイパススイッチ20には負荷電流ILの1/Nの電流が流れる。
The bypass switch 20 is a mechanical switch, and is connected between the bypass terminal T1 and the output terminal T4. The bypass switch 20 is turned on by the control device 5 when the operation unit 4 is operated to select the bypass power supply mode. In the bypass power supply mode, the N bypass switches 20 included in the N uninterruptible power supplies U1 to UN are turned on, and a load current IL is supplied from the bypass AC power supply 6 to the load 8 via the parallel connection of the N bypass switches 20. At this time, the capacity of the bypass switches 20 is sufficiently large, so that a current of 1/N of the load current IL flows through each bypass switch 20.
リアクトル21は、バイパス端子T1と、バイパスモジュール22の一方端子22aとの間に接続される。バイパスモジュール22の他方端子22bは、出力端子T4に接続される。リアクトル21は、バイパスモジュール22の他方端子22bと、出力端子T4との間に接続されていても構わない。この場合は、バイパスモジュール22の一方端子22aは、バイパス端子T1に直接接続される。
The reactor 21 is connected between the bypass terminal T1 and one terminal 22a of the bypass module 22. The other terminal 22b of the bypass module 22 is connected to the output terminal T4. The reactor 21 may be connected between the other terminal 22b of the bypass module 22 and the output terminal T4. In this case, the one terminal 22a of the bypass module 22 is directly connected to the bypass terminal T1.
図4は、バイパスモジュール22の構成を示す回路ブロック図である。図4において、バイパスモジュール22は、半導体スイッチ23、停電検出部26、通信部27、制御部28、および記憶部29を含む。半導体スイッチ23は、互いに逆並列に接続された一対のサイリスタ24,25を含む。
FIG. 4 is a circuit block diagram showing the configuration of the bypass module 22. In FIG. 4, the bypass module 22 includes a semiconductor switch 23, a power outage detection unit 26, a communication unit 27, a control unit 28, and a memory unit 29. The semiconductor switch 23 includes a pair of thyristors 24, 25 connected in antiparallel to each other.
サイリスタ24のアノードおよびカソードは、バイパスモジュール22の端子22a,22bにそれぞれ接続される。サイリスタ25のアノードおよびカソードは、バイパスモジュール22の端子22b,22aにそれぞれ接続される。なお、半導体スイッチ23は、サイリスタ24,25以外の半導体素子(たとえばトランジスタ、ダイオード等)で構成されていても構わない。
The anode and cathode of the thyristor 24 are connected to the terminals 22a and 22b, respectively, of the bypass module 22. The anode and cathode of the thyristor 25 are connected to the terminals 22b and 22a, respectively, of the bypass module 22. Note that the semiconductor switch 23 may be composed of semiconductor elements other than the thyristors 24 and 25 (e.g., transistors, diodes, etc.).
半導体スイッチ23は、制御部28によって制御され、バイパスECO給電モード時にオンされる。半導体スイッチ23がオンされると、バイパス交流電源6からリアクトル21および半導体スイッチ23を介して負荷8に交流電力が供給される。
The semiconductor switch 23 is controlled by the control unit 28 and is turned on in the bypass ECO power supply mode. When the semiconductor switch 23 is turned on, AC power is supplied from the bypass AC power supply 6 to the load 8 via the reactor 21 and the semiconductor switch 23.
無停電電源システム1全体としては、N個の半導体スイッチ23がオンされ、バイパス交流電源6からN個のリアクトル21および半導体スイッチ23の直列接続体を介して負荷8に負荷電流ILが供給される。
In the uninterruptible power supply system 1 as a whole, N semiconductor switches 23 are turned on, and a load current IL is supplied from the bypass AC power supply 6 to the load 8 via a series connection of N reactors 21 and semiconductor switches 23.
リアクトル21は、このときにN個の半導体スイッチ23に流れる電流の大きさのばらつきを小さく抑制するために設けられている。これについては、後述する。バイパス交流電源6の停電が発生すると、半導体スイッチ23がオフされ、バイパス交流電源6と負荷8との間が瞬時に遮断される。
The reactor 21 is provided to reduce the variation in the magnitude of the current flowing through the N semiconductor switches 23 at this time. This will be described later. When a power outage occurs in the bypass AC power supply 6, the semiconductor switch 23 is turned off, and the bypass AC power supply 6 is instantly disconnected from the load 8.
停電検出部26は、バイパス端子T1に現れる交流電圧VI(すなわちバイパス交流電源6から供給される交流電圧VI)の瞬時値を検出し、その検出値に基づいてバイパス交流電源6の停電が発生しているか否かを判別し、判別結果を示す停電検出信号φ26を出力する。
The power outage detection unit 26 detects the instantaneous value of the AC voltage VI (i.e., the AC voltage VI supplied from the bypass AC power supply 6) that appears at the bypass terminal T1, determines whether or not a power outage has occurred in the bypass AC power supply 6 based on the detected value, and outputs a power outage detection signal φ26 that indicates the determination result.
たとえば、停電検出部26は、交流電圧VIが下限値よりも高い場合には、バイパス交流電源6から交流電圧VIが正常に供給されており、バイパス交流電源6は健全であると判別する。また停電検出部26は、交流電圧VIが下限値よりも低い場合には、バイパス交流電源6から交流電圧VIが正常に供給されておらず、バイパス交流電源6の停電が発生していると判別する。
For example, when the AC voltage VI is higher than the lower limit, the power outage detection unit 26 determines that the AC voltage VI is being supplied normally from the bypass AC power supply 6 and that the bypass AC power supply 6 is healthy. When the AC voltage VI is lower than the lower limit, the power outage detection unit 26 determines that the AC voltage VI is not being supplied normally from the bypass AC power supply 6 and that a power outage of the bypass AC power supply 6 has occurred.
バイパス交流電源6が健全である場合には、停電検出信号φ26は非活性化レベルの「H」レベルにされる。バイパス交流電源6の停電が発生している場合には、停電検出信号φ26は活性化レベルの「L」レベルにされる。
When the bypass AC power supply 6 is healthy, the power outage detection signal φ26 is set to the inactive "H" level. When a power outage occurs in the bypass AC power supply 6, the power outage detection signal φ26 is set to the active "L" level.
通信部27は、通信線3を介して無停電電源装置U1内のパワーモジュールP1~PM、他の無停電電源装置U2~UM、および制御装置5に接続されており、それらと制御部28との間で種々の信号および情報を授受する。
The communication unit 27 is connected to the power modules P1-PM in the uninterruptible power supply U1, the other uninterruptible power supplies U2-UM, and the control device 5 via the communication line 3, and transmits and receives various signals and information between them and the control unit 28.
制御部28は、制御装置5から通信線3および通信部27を介してバイパスECO給電モードの実行が指令され、かつ停電検出信号φ26が非活性化レベルの「H」レベルである場合には、半導体スイッチ23をオンさせる。
The control unit 28 turns on the semiconductor switch 23 when the control device 5 issues a command to execute the bypass ECO power supply mode via the communication line 3 and the communication unit 27, and the power failure detection signal φ26 is at the inactivation level of "H".
また制御部28は、停電検出信号φ26が活性化レベルの「L」レベルにされた場合には、半導体スイッチ23をオフさせる。停電検出信号φ26は、制御部28、通信部27、および通信線3を介してパワーモジュールP1~PMに与えられる。
In addition, when the power failure detection signal φ26 is set to the "L" level, which is the activation level, the control unit 28 turns off the semiconductor switch 23. The power failure detection signal φ26 is provided to the power modules P1 to PM via the control unit 28, the communication unit 27, and the communication line 3.
また制御部28は、制御装置5(図5)から通信線3および通信部27を介して与えられる信号φIsによって示される分担電流Isを効率よく供給するために必要な台数mのパワーモジュールPを選択し、選択結果を示す信号SE1~SEMを出力する。mは、1以上でM以下の整数である。選択信号SE1~SEMを代表的に総称して選択信号SEと称する場合がある。
The control unit 28 also selects the number m of power modules P required to efficiently supply the shared current Is indicated by the signal φIs provided from the control device 5 (FIG. 5) via the communication line 3 and the communication unit 27, and outputs signals SE1 to SEM indicating the selection result. m is an integer greater than or equal to 1 and less than or equal to M. The selection signals SE1 to SEM may be collectively referred to as the selection signal SE.
m台のパワーモジュールPを選択するのは、全パワーモジュールP1~PMを選択すると、各パワーモジュールPの出力電流が小さくなり過ぎて、各パワーモジュールPの効率が低下するからである。
The reason for selecting m power modules P is that if all power modules P1 to PM were selected, the output current of each power module P would be too small, reducing the efficiency of each power module P.
選択信号SE1~SEMは、それぞれパワーモジュールP1~PMに対応している。あるパワーモジュールPが選択された場合には、そのパワーモジュールPに対応する選択信号SEは選択レベルの「H」レベルにされる。あるパワーモジュールPが選択されていない場合には、そのパワーモジュールPに対応する選択信号SEは非選択レベルの「L」レベルにされる。
The selection signals SE1 to SEM correspond to the power modules P1 to PM, respectively. When a power module P is selected, the selection signal SE corresponding to that power module P is set to the selection level "H". When a power module P is not selected, the selection signal SE corresponding to that power module P is set to the non-selection level "L".
制御部28は、分担電流Isのm分の1の副分担電流Issを求め、その副分担電流Issを示す信号φIssを各パワーモジュールPに与える。バイパス交流電源6の停電が発生した場合には、選択されたm台のパワーモジュールPの各々が、分担電流Isのm分の1の副分担電流Issを負荷8に供給する。
The control unit 28 calculates a sub-shared current Iss that is 1/m of the shared current Is, and provides a signal φIss indicating the sub-shared current Iss to each power module P. In the event of a power outage in the bypass AC power supply 6, each of the selected m power modules P supplies a sub-shared current Iss that is 1/m of the shared current Is to the load 8.
この場合において制御部28は、バイパス交流電源6の停電が発生する度に、選択するm台のパワーモジュールPの組み合わせを変更する。これは、特定のパワーモジュールPが繰り返し選択されて、そのパワーモジュールPが他のパワーモジュールPよりも早く劣化することを防止するためである。記憶部29には、m台のパワーモジュールPの組み合わせを示すテーブルが格納されている。
In this case, the control unit 28 changes the combination of the m power modules P to be selected each time a power outage occurs in the bypass AC power supply 6. This is to prevent a specific power module P from being repeatedly selected and deteriorating faster than other power modules P. The memory unit 29 stores a table showing the combinations of the m power modules P.
図5は、記憶部29に格納されたテーブルを示す図である。図5において、このテーブルは、M=5でm=3の場合におけるパワーモジュールPの組み合わせを示している。このテーブルでは、10個のパターンが示されている。各パターンにおいて、〇印が付されたパワーモジュールPが選択される。
FIG. 5 is a diagram showing a table stored in the memory unit 29. In FIG. 5, this table shows combinations of power modules P when M=5 and m=3. In this table, 10 patterns are shown. In each pattern, the power module P marked with a circle is selected.
パターン1では、5台のパワーモジュールP1~P5のうちのパワーモジュールP1~P3が選択される。パターン2では、パワーモジュールP1,P2,P4が選択される。パターン3では、パワーモジュールP1,P2,P5が選択される。パターン4では、パワーモジュールP1,P3,P4が選択される。パターン5では、パワーモジュールP1,P3,P5が選択される。パターン6では、パワーモジュールP1,P4,P5が選択される。パターン7では、パワーモジュールP2~P4が選択される。パターン8では、パワーモジュールP2,P3,P5が選択される。パターン9では、パワーモジュールP2,P4,P5が選択される。パターン10では、パワーモジュールP3~P5が選択される。
In pattern 1, power modules P1 to P3 are selected out of the five power modules P1 to P5. In pattern 2, power modules P1, P2, and P4 are selected. In pattern 3, power modules P1, P2, and P5 are selected. In pattern 4, power modules P1, P3, and P4 are selected. In pattern 5, power modules P1, P3, and P5 are selected. In pattern 6, power modules P1, P4, and P5 are selected. In pattern 7, power modules P2 to P4 are selected. In pattern 8, power modules P2, P3, and P5 are selected. In pattern 9, power modules P2, P4, and P5 are selected. In pattern 10, power modules P3 to P5 are selected.
制御部28は、1回目はパターン1の3台のパワーモジュールP1~P3を選択し、2~10回目はそれぞれパターン2からパターン10の3台のパワーモジュールPを選択し、11回目は再びパターン1の3台のパワーモジュールP1~P3を選択する。以下、同様である。
The control unit 28 selects three power modules P1 to P3 of pattern 1 the first time, selects three power modules P of patterns 2 to 10 the second to tenth times, and again selects three power modules P1 to P3 of pattern 1 the eleventh time. This is the same as above.
M=5の場合、記憶部29にはmが1,2,3,4である場合の4つのテーブルが格納されている。制御部28は、mの値に応じて4つのテーブルのうちのいずれかのテーブルを選択し、そのテーブルを参照してm台のパワーモジュールPを選択する。m=5である場合には、制御部28は常に全部のパワーモジュールP1~P5を選択する。
When M=5, the memory unit 29 stores four tables for m=1, 2, 3, and 4. The control unit 28 selects one of the four tables according to the value of m, and refers to that table to select m power modules P. When m=5, the control unit 28 always selects all power modules P1 to P5.
再び図3を参照して、各パワーモジュールPは、入力端子T5、直流端子T6、および出力端子T7を含む。入力端子T5、直流端子T6、および出力端子T7は、それぞれ対応する無停電電源装置U1の入力端子T2、直流端子T3、および出力端子T4に接続されている。
Referring again to FIG. 3, each power module P includes an input terminal T5, a DC terminal T6, and an output terminal T7. The input terminal T5, DC terminal T6, and output terminal T7 are connected to the input terminal T2, DC terminal T3, and output terminal T4 of the corresponding uninterruptible power supply U1, respectively.
パワーモジュールPは、交流電源7の健全時には、交流電源7から供給される交流電力を直流電力に変換して対応するバッテリB1に蓄える。交流電源7の停電が発生すると、パワーモジュールPは、バッテリB1の充電を停止する。
When the AC power source 7 is healthy, the power module P converts the AC power supplied from the AC power source 7 into DC power and stores it in the corresponding battery B1. When a power outage occurs in the AC power source 7, the power module P stops charging the battery B1.
バイパスECO給電モード時において停電検出信号φ26(図4)が非活性化レベルの「H」レベルである場合には、各パワーモジュールPは、出力端子T4に現れる交流電圧VOに対抗するカウンタ電圧VCを出力し、他のパワーモジュールPおよび負荷8と電流を授受しない待機状態にされる。換言すると、このとき各パワーモジュールPはカウンタ電圧VCを出力し、0Aを出力する。
When the power failure detection signal φ26 (FIG. 4) is at the inactive "H" level during bypass ECO power supply mode, each power module P outputs a counter voltage VC that opposes the AC voltage VO appearing at the output terminal T4, and is placed in a standby state in which no current is exchanged with other power modules P or the load 8. In other words, at this time, each power module P outputs the counter voltage VC and outputs 0 A.
停電検出信号φ26が活性化レベルの「L」レベルにされると、パワーモジュールP1~PMのうちの制御部28(図4)によって選択されたm台のパワーモジュールPの各々は、制御部28からの信号φIssによって示される副分担電流Issを負荷8に供給する。
When the power failure detection signal φ26 is set to the "L" level, which is the activation level, each of the m power modules P selected by the control unit 28 (FIG. 4) from among the power modules P1 to PM supplies the sub-shared current Iss indicated by the signal φIss from the control unit 28 to the load 8.
図6は、パワーモジュールP1の構成を示す回路ブロック図である。図6において、このパワーモジュールP1は、端子T5~T7(図3)に加え、ヒューズF1~F3、スイッチS1~S3、コンデンサC1~C3、リアクトルL1~L3、コンバータ31、直流ラインDL、インバータ32、双方向チョッパ33、電流検出器CD1~CD3、通信部34、制御部35、および故障検出部36を備える。他のパワーモジュールP2~PMの各々は、パワーモジュールP1と同様の構成である。
FIG. 6 is a circuit block diagram showing the configuration of power module P1. In FIG. 6, in addition to terminals T5 to T7 (FIG. 3), this power module P1 includes fuses F1 to F3, switches S1 to S3, capacitors C1 to C3, reactors L1 to L3, converter 31, DC line DL, inverter 32, bidirectional chopper 33, current detectors CD1 to CD3, communication unit 34, control unit 35, and fault detection unit 36. Each of the other power modules P2 to PM has the same configuration as power module P1.
スイッチS1の一方端子はヒューズF1を介して入力端子T5に接続され、その他方端子はリアクトルL1を介してコンバータ31の入力ノードに接続される。コンデンサC1は、スイッチS1の他方端子に接続される。コンバータ31の出力ノードは、直流ラインDLを介してインバータ32の入力ノードに接続されるとともに、双方向チョッパ33の一方入出力ノードに接続される。コンデンサC3は、直流ラインDLに接続される。パワーモジュールP1~PNの直流ラインDLは、互いに接続されている。
One terminal of the switch S1 is connected to the input terminal T5 via the fuse F1, and the other terminal is connected to the input node of the converter 31 via the reactor L1. The capacitor C1 is connected to the other terminal of the switch S1. The output node of the converter 31 is connected to the input node of the inverter 32 via the DC line DL, and is also connected to one input/output node of the bidirectional chopper 33. The capacitor C3 is connected to the DC line DL. The DC lines DL of the power modules P1 to PN are connected to each other.
インバータ32の出力ノードはリアクトルL2を介してスイッチS2の一方端子に接続され、スイッチS2の他方端子はヒューズF2を介して出力端子T7に接続される。コンデンサC2は、スイッチS2の一方端子に接続される。スイッチS3の一方端子はヒューズF3を介して直流端子T6に接続され、その他方端子はリアクトルL3を介して双方向チョッパ33の他方入出力ノードに接続される。
The output node of the inverter 32 is connected to one terminal of a switch S2 via a reactor L2, and the other terminal of the switch S2 is connected to an output terminal T7 via a fuse F2. A capacitor C2 is connected to one terminal of the switch S2. One terminal of the switch S3 is connected to a DC terminal T6 via a fuse F3, and the other terminal is connected to the other input/output node of the bidirectional chopper 33 via a reactor L3.
ヒューズF1は、過電流が流れた場合にブローされ、コンバータ31などを保護する。スイッチS1は、制御部35によって制御される。交流電源7から交流電圧Viが正常に供給されている場合(交流電源7の健全時)には、スイッチS1はオンされる。交流電源7から交流電圧Viが正常に供給されていない場合(交流電源7の停電時)には、スイッチS1はオフされる。
Fuse F1 is blown when an overcurrent flows, protecting converter 31 and other components. Switch S1 is controlled by control unit 35. When AC voltage Vi is being supplied normally from AC power supply 7 (when AC power supply 7 is functioning properly), switch S1 is turned on. When AC voltage Vi is not being supplied normally from AC power supply 7 (when AC power supply 7 is experiencing a power outage), switch S1 is turned off.
コンデンサC1およびリアクトルL1は交流フィルタを構成する。交流フィルタは、ローパスフィルタであり、交流電源7から供給される商用周波数の交流電力を通過させ、コンバータ31で発生するスイッチング周波数の信号を遮断する。
Capacitor C1 and reactor L1 form an AC filter. The AC filter is a low-pass filter that passes commercial frequency AC power supplied from AC power source 7 and blocks the switching frequency signal generated by converter 31.
コンバータ31は、制御部35によって制御され、交流電源7の健全時には、交流電源7からの交流電力を直流電力に変換し、その直流電力を直流ラインDLを介してインバータ32および双方向チョッパ33に与える。コンバータ31は、直流ラインDLの直流電圧VDが目標直流電圧VDTに一致するように、直流電流を直流ラインDLに出力する。交流電源7の停電時には、コンバータ31の運転は停止される。コンデンサC1、リアクトルL1、およびコンバータ31は、交流電力を直流電力に変換する「順変換器」の一実施例を構成する。コンデンサC3は、直流ラインDLの直流電圧VDを平滑化および安定化させる。
The converter 31 is controlled by the control unit 35, and when the AC power supply 7 is healthy, it converts the AC power from the AC power supply 7 into DC power and supplies the DC power to the inverter 32 and the bidirectional chopper 33 via the DC line DL. The converter 31 outputs a DC current to the DC line DL so that the DC voltage VD of the DC line DL matches the target DC voltage VDT. When the AC power supply 7 experiences a power outage, the operation of the converter 31 is stopped. The capacitor C1, the reactor L1, and the converter 31 constitute one embodiment of a "forward converter" that converts AC power into DC power. The capacitor C3 smoothes and stabilizes the DC voltage VD of the DC line DL.
ヒューズF3は、過電流が流れた場合にブローされ、バッテリB1、双方向チョッパ33などを保護する。スイッチS3は、パワーモジュールP1を使用する場合にオンされ、たとえばバッテリB1のメンテナンス時にオフされる。リアクトルL3は、ローパスフィルタであり、直流電力を通過させ、双方向チョッパ33で発生するスイッチング周波数の信号を遮断する。
Fuse F3 is blown in the event of an overcurrent, protecting battery B1, bidirectional chopper 33, etc. Switch S3 is turned on when power module P1 is in use, and turned off, for example, during maintenance of battery B1. Reactor L3 is a low-pass filter that passes DC power and blocks the switching frequency signal generated by bidirectional chopper 33.
双方向チョッパ33は、制御部35によって制御され、交流電源7の健全時にはコンバータ31によって生成される直流電力をバッテリB1に蓄え、バイパス交流電源6の停電時にはバッテリB1の直流電力をインバータ32に供給する。双方向チョッパ33は、交流電源7の健全時には、バッテリB1の端子間電圧VBが目標直流電圧VBTになるように、バッテリB1に直流電流を供給する。双方向チョッパ33は、バイパス交流電源6の停電時には、直流ラインDLの直流電圧VDが目標直流電圧VDTに一致するように、直流電流を直流ラインDLに出力する。
The bidirectional chopper 33 is controlled by the control unit 35, and stores the DC power generated by the converter 31 in the battery B1 when the AC power supply 7 is healthy, and supplies the DC power of the battery B1 to the inverter 32 when the bypass AC power supply 6 fails. When the AC power supply 7 is healthy, the bidirectional chopper 33 supplies a DC current to the battery B1 so that the terminal voltage VB of the battery B1 becomes the target DC voltage VBT. When the bypass AC power supply 6 fails, the bidirectional chopper 33 outputs a DC current to the DC line DL so that the DC voltage VD of the DC line DL becomes equal to the target DC voltage VDT.
インバータ32は、制御部35によって制御される。停電検出信号φ26(図4)が非活性化レベルの「H」レベルである場合には、インバータ32は、出力端子T7に現れる交流電圧VOに対抗するカウンタ電圧VCを出力し、他のパワーモジュールP2~PMおよび負荷8と電流を授受しない待機状態にされる。換言すると、このときインバータ32はカウンタ電圧VCを出力し、0Aを出力する。
The inverter 32 is controlled by the control unit 35. When the power failure detection signal φ26 (FIG. 4) is at the inactivation level "H", the inverter 32 outputs a counter voltage VC that opposes the AC voltage VO appearing at the output terminal T7, and is placed in a standby state in which it does not exchange current with the other power modules P2 to PM or the load 8. In other words, at this time the inverter 32 outputs the counter voltage VC and outputs 0 A.
対応するパワーモジュールP1が制御部28(図4)によって選択されている場合において、停電検出信号φ26が活性化レベルの「L」レベルにされた場合には、インバータ32は、副分担電流Issを負荷8に供給する。
When the corresponding power module P1 is selected by the control unit 28 (Figure 4), if the power failure detection signal φ26 is set to the "L" level, which is the activation level, the inverter 32 supplies the secondary current Iss to the load 8.
リアクトルL2およびコンデンサC2は交流フィルタを構成する。交流フィルタは、ローパスフィルタであり、インバータ32によって生成された商用周波数の交流電力を通過させ、インバータ32で発生するスイッチング周波数の信号を遮断する。換言すると、交流フィルタは、インバータ32の出力電圧の波形を正弦波に整形する。インバータ32、リアクトルL2、およびコンデンサC2は、直流電力を交流電力に変換する「逆変換器」の一実施例を構成する。
The reactor L2 and the capacitor C2 form an AC filter. The AC filter is a low-pass filter that passes commercial frequency AC power generated by the inverter 32 and blocks signals of the switching frequency generated by the inverter 32. In other words, the AC filter shapes the waveform of the output voltage of the inverter 32 into a sine wave. The inverter 32, the reactor L2, and the capacitor C2 form one embodiment of an "inverter" that converts DC power to AC power.
スイッチS2は、パワーモジュールP1を使用する場合にオンされ、インバータ32が故障した場合およびインバータ32のメンテナンス時にオフされる。入力端子T5の交流電圧Vi(すなわち交流電源7から供給される交流電圧)と、出力端子T7の交流電圧VO(すなわち出力電圧)と、直流端子T6の直流電圧VB(すなわちバッテリB1の端子間電圧)と、直流ラインDLの直流電圧VDとは、制御部35に与えられる。
The switch S2 is turned on when the power module P1 is used, and is turned off when the inverter 32 fails or during maintenance of the inverter 32. The AC voltage Vi at the input terminal T5 (i.e., the AC voltage supplied from the AC power source 7), the AC voltage VO at the output terminal T7 (i.e., the output voltage), the DC voltage VB at the DC terminal T6 (i.e., the voltage between the terminals of the battery B1), and the DC voltage VD of the DC line DL are provided to the control unit 35.
電流検出器CD1は、リアクトルL1に流れる交流電流(すなわちコンバータ31の入力電流)の瞬時値を検出し、その検出値を示す信号を制御部35に与える。電流検出器CD2は、リアクトルL2に流れる交流電流(すなわちインバータ32の出力電流)の瞬時値を検出し、その検出値を示す信号を制御部35に与える。電流検出器CD3は、リアクトルL3に流れる直流電流(すなわちバッテリB1に流れる直流電流)の瞬時値を検出し、その検出値を示す信号を制御部35に与える。
Current detector CD1 detects the instantaneous value of the AC current flowing through reactor L1 (i.e., the input current of converter 31) and provides a signal indicating the detected value to control unit 35. Current detector CD2 detects the instantaneous value of the AC current flowing through reactor L2 (i.e., the output current of inverter 32) and provides a signal indicating the detected value to control unit 35. Current detector CD3 detects the instantaneous value of the DC current flowing through reactor L3 (i.e., the DC current flowing through battery B1) and provides a signal indicating the detected value to control unit 35.
通信部34は、制御部35と通信線3の間に設けられ、バイパスモジュール22、他のパワーモジュールP2~PM、制御装置5との間で種々の信号および情報を授受する。
The communication unit 34 is provided between the control unit 35 and the communication line 3, and transmits and receives various signals and information between the bypass module 22, the other power modules P2 to PM, and the control device 5.
故障検出部36は、対応するインバータ32が正常であるか否かを判別し、判別結果を示す故障検出信号φ36を出力する。インバータ32が正常である場合には、故障検出信号φ36は非活性化レベルの「L」レベルにされる。インバータ32が故障している場合には、故障検出信号φ36は活性化レベルの「H」レベルにされる。
The fault detection unit 36 determines whether the corresponding inverter 32 is normal or not, and outputs a fault detection signal φ36 indicating the determination result. If the inverter 32 is normal, the fault detection signal φ36 is set to the inactivation level "L" level. If the inverter 32 is faulty, the fault detection signal φ36 is set to the activation level "H" level.
故障検出信号φ36は、制御部35に与えられる。制御部35は、故障検出信号φ36は非活性化レベルの「L」レベルである場合には、インバータ32を制御する。故障検出信号φ36は活性化レベルの「H」レベルである場合には、制御部35は、インバータ32の運転を停止させるとともに、スイッチS2をオフさせる。
The fault detection signal φ36 is given to the control unit 35. When the fault detection signal φ36 is at the "L" level, which is the inactivation level, the control unit 35 controls the inverter 32. When the fault detection signal φ36 is at the "H" level, which is the activation level, the control unit 35 stops the operation of the inverter 32 and turns off the switch S2.
また、故障検出信号φ36は、制御部35、通信部34、通信線3、および通信部27(図4)を介して制御部28に与えられる。故障検出信号φ36は活性化レベルの「H」レベルである場合には、制御部28は、その故障検出信号φ36に対応するパワーモジュール(この場合はP1)以外のパワーモジュールP2~PMからm台のパワーモジュールPを選択する。
Failure detection signal φ36 is also provided to control unit 28 via control unit 35, communication unit 34, communication line 3, and communication unit 27 (FIG. 4). When failure detection signal φ36 is at the "H" level, which is the activation level, control unit 28 selects m power modules P from power modules P2 to PM other than the power module corresponding to that failure detection signal φ36 (P1 in this case).
制御部35は、交流電圧Vi,VOの瞬時値、直流電圧VB,VDの瞬時値、電流検出器CD1~CD3の検出値、故障検出信号φ36、制御装置5および制御部28から通信線3および通信部34を介して供給される種々の信号および情報に基づいて、パワーモジュールP1全体を制御する。
The control unit 35 controls the entire power module P1 based on the instantaneous values of the AC voltages Vi, VO, the instantaneous values of the DC voltages VB, VD, the detection values of the current detectors CD1 to CD3, the fault detection signal φ36, and various signals and information supplied from the control device 5 and the control unit 28 via the communication line 3 and the communication unit 34.
特に、制御部35は、交流電圧Viの瞬時値、直流ラインDLの直流電圧VDの瞬時値、電流検出器CD1の検出値などに基づいて、コンバータ31を制御する。これにより、直流ラインDLの直流電圧VDは、目標直流電圧VDTに維持される。
In particular, the control unit 35 controls the converter 31 based on the instantaneous value of the AC voltage Vi, the instantaneous value of the DC voltage VD of the DC line DL, the detection value of the current detector CD1, etc. As a result, the DC voltage VD of the DC line DL is maintained at the target DC voltage VDT.
また制御部35は、交流電圧Viの瞬時値、直流ラインDLの直流電圧VDの瞬時値、直流電圧VBの瞬時値、電流検出器CD3の出力信号などに基づいて、双方向チョッパ33を制御する。これにより、バッテリB1の端子間電圧VBが目標直流電圧VBTに維持される。
The control unit 35 also controls the bidirectional chopper 33 based on the instantaneous value of the AC voltage Vi, the instantaneous value of the DC voltage VD of the DC line DL, the instantaneous value of the DC voltage VB, the output signal of the current detector CD3, etc. This maintains the inter-terminal voltage VB of the battery B1 at the target DC voltage VBT.
また制御部35は、交流電圧VOの瞬時値、電流検出器CD2の出力信号、停電検出信号φ26、信号φIss、故障検出信号φ36などに基づいて、インバータ32を制御する。これにより、インバータ32の出力電流が副分担電流Issまたは0Aに維持される。
The control unit 35 also controls the inverter 32 based on the instantaneous value of the AC voltage VO, the output signal of the current detector CD2, the power failure detection signal φ26, the signal φIss, the fault detection signal φ36, etc. This maintains the output current of the inverter 32 at the secondary current Iss or 0 A.
図7は、制御部35のうちのインバータ32の制御に関連する部分の構成を示すブロック図である。図7において、制御部35は、電流指令部41、電圧制御部42、電流制御部43、およびPWM(Pulse Width Modulation)制御部44を含む。
FIG. 7 is a block diagram showing the configuration of the portion of the control unit 35 that is related to the control of the inverter 32. In FIG. 7, the control unit 35 includes a current command unit 41, a voltage control unit 42, a current control unit 43, and a PWM (Pulse Width Modulation) control unit 44.
電流指令部41は、バイパスモジュール22(図4)から与えられる停電検出信号φ26、選択信号SE1、および信号φIssに基づいて、電流指令値Ic1を生成する。選択信号SE1が非選択レベルの「L」レベルである場合には、停電検出信号φ26に関係なく、電流指令値Ic1は0Aに応じた値に設定される。
The current command unit 41 generates a current command value Ic1 based on the power failure detection signal φ26, the selection signal SE1, and the signal φIss provided by the bypass module 22 (FIG. 4). When the selection signal SE1 is at the "L" level, which is the non-selection level, the current command value Ic1 is set to a value corresponding to 0 A, regardless of the power failure detection signal φ26.
選択信号SE1が選択レベルの「H」レベルである場合において、停電検出信号φ26が非活性化レベルの「H」レベルである場合(バイパス交流電源6の健全時)には、電流指令値Ic1は0Aに応じた値に設定される。
When the selection signal SE1 is at the "H" level of the selection level, and the power failure detection signal φ26 is at the "H" level of the inactivation level (when the bypass AC power supply 6 is healthy), the current command value Ic1 is set to a value corresponding to 0 A.
選択信号SE1が選択レベルの「H」レベルである場合において、停電検出信号φ26が活性化レベルの「L」レベルである場合(バイパス交流電源6の停電時)には、電流指令値Ic1は信号φIssによって示される副分担電流Issに応じた値に設定される。
When the selection signal SE1 is at the "H" level of the selection level and the power failure detection signal φ26 is at the "L" level of the activation level (when the bypass AC power supply 6 is at a power failure), the current command value Ic1 is set to a value according to the sub-shared current Iss indicated by the signal φIss.
電圧制御部42は、電流指令部41からの電流指令値Ic1と電流検出器CD2の検出値Io1(パワーモジュールU1の出力電流)との偏差を求め、その偏差がなくなるように電圧指令値Vcを生成する。電流制御部43は、出力電圧VOと電圧指令値Vcの偏差を求め、その偏差がなくなるように電流指令値Icを生成する。
The voltage control unit 42 finds the deviation between the current command value Ic1 from the current command unit 41 and the detection value Io1 of the current detector CD2 (the output current of the power module U1), and generates a voltage command value Vc so that the deviation is eliminated. The current control unit 43 finds the deviation between the output voltage VO and the voltage command value Vc, and generates a current command value Ic so that the deviation is eliminated.
PWM制御部44は、故障検出信号φ36が非活性化レベルの「L」レベルである場合には、出力端子T7の交流電圧VOに同期して動作し、電流指令値Icに従ってPWM信号を生成し、そのPWM信号によってインバータ32を制御する。故障検出信号φ36が活性化レベルの「H」レベルである場合には、PWM制御部44は、インバータ32の運転を停止する。
When the fault detection signal φ36 is at the inactivation level "L", the PWM control unit 44 operates in synchronization with the AC voltage VO at the output terminal T7, generates a PWM signal according to the current command value Ic, and controls the inverter 32 with the PWM signal. When the fault detection signal φ36 is at the activation level "H", the PWM control unit 44 stops the operation of the inverter 32.
換言すると、バイパス交流電源6の健全時には、インバータ32は、他のパワーモジュールP2~PMの出力電圧VOに応じた値のカウンタ電圧VCを出力するとともに0Aを出力し、他のパワーモジュールP2~PMおよび負荷8と電流を授受しない待機状態にされる。
In other words, when the bypass AC power supply 6 is healthy, the inverter 32 outputs a counter voltage VC whose value corresponds to the output voltage VO of the other power modules P2 to PM, outputs 0 A, and is in a standby state in which no current is exchanged with the other power modules P2 to PM or the load 8.
対応する選択信号SE1が選択レベルの「H」レベルにされている場合において、バイパス交流電源6の停電が発生したときには、インバータ32は副分担電流Issを出力する。このときインバータ32は既に起動されて待機状態にされているので、電流指令値Ic1が増大された場合にはインバータ32の出力電流は迅速かつスムーズに増大する。
When the corresponding selection signal SE1 is at the "H" level, which is the selection level, if a power outage occurs in the bypass AC power supply 6, the inverter 32 outputs the secondary shared current Iss. At this time, the inverter 32 has already been started and is in a standby state, so when the current command value Ic1 is increased, the output current of the inverter 32 increases quickly and smoothly.
対応する選択信号SE1が非選択レベルの「L」レベルにされている場合には、バイパス交流電源6が健全か否かに関係なく、0Aを出力し、待機状態に維持される。
When the corresponding selection signal SE1 is at the non-selection level "L", the bypass AC power supply 6 outputs 0 A and is maintained in standby mode regardless of whether it is healthy or not.
次に、この無停電電源システムの動作について説明する。バイパス交流電源6の健全時には、バイパスECO給電モードが実行され、N台の無停電電源装置U1~UN(図1)に含まれるN個の半導体スイッチ23(図4)がオンされ、各無停電電源装置Uにおいてバイパス交流電源6からリアクトル21および半導体スイッチ23を介して負荷8に交流電力が供給される。このとき、リアクトル21により、N個の半導体スイッチ23に流れる電流の大きさのばらつきが小さく抑制される。
Next, the operation of this uninterruptible power supply system will be described. When the bypass AC power supply 6 is healthy, the bypass ECO power supply mode is executed, N semiconductor switches 23 (FIG. 4) included in N uninterruptible power supplies U1 to UN (FIG. 1) are turned on, and AC power is supplied from the bypass AC power supply 6 to the load 8 via the reactor 21 and semiconductor switch 23 in each uninterruptible power supply U. At this time, the reactor 21 suppresses the variation in the magnitude of the current flowing through the N semiconductor switches 23 to a small value.
また、各無停電電源装置Uの各パワーモジュールP(図6)において、コンバータ31および双方向チョッパ33によってバッテリBが充電される。また、各パワーモジュールPにおいてインバータ32は、制御部35(図6、図7)によって制御され、電流を出力せずにカウンタ電圧VCを出力する待機状態にされる。
In addition, in each power module P (FIG. 6) of each uninterruptible power supply U, the battery B is charged by the converter 31 and bidirectional chopper 33. In each power module P, the inverter 32 is controlled by the control unit 35 (FIGS. 6 and 7) and is placed in a standby state in which it outputs the counter voltage VC without outputting any current.
負荷電流ILが電流検出器2(図1)によって検出され、その検出値に基づいて制御装置5(図2)によって各無停電電源装置Uの分担電流Isが求められ、その分担電流Isを示す信号φIsが各無停電電源装置Uの制御部28(図4)に与えられる。
The load current IL is detected by the current detector 2 (Figure 1), and the control device 5 (Figure 2) calculates the shared current Is of each uninterruptible power supply U based on the detected value, and a signal φIs indicating the shared current Is is sent to the control unit 28 (Figure 4) of each uninterruptible power supply U.
制御部28により、信号φIsによって示される分担電流Isを効率よく供給するために必要な数mのパワーモジュールPが選択されるとともに、選択されたパワーモジュールPが負荷8に供給すべき副分担電流Issが求められる。
The control unit 28 selects the number m of power modules P required to efficiently supply the shared current Is indicated by the signal φIs, and determines the sub-shared current Iss that the selected power modules P should supply to the load 8.
バイパス交流電源6の停電が発生すると、N個の半導体スイッチ23がオフされ、バイパス交流電源6と負荷8の間が瞬時に遮断される。また、各無停電電源装置Uの選択されたm台のパワーモジュールPの各々から負荷8に副分担電流Issが供給され、負荷8の運転が継続される。
When a power outage occurs in the bypass AC power supply 6, the N semiconductor switches 23 are turned off, and the bypass AC power supply 6 is instantly disconnected from the load 8. In addition, the sub-shared current Iss is supplied to the load 8 from each of the selected m power modules P of each uninterruptible power supply U, and the operation of the load 8 continues.
バイパス交流電源6が健全状態に復旧すると、N台の無停電電源装置U1~UN(図1)に含まれるN個の半導体スイッチ23(図4)がオンされ、各無停電電源装置Uにおいて、バイパス交流電源6からリアクトル21および半導体スイッチ23を介して負荷8に交流電力が供給されるとともに、各パワーモジュールPが待機状態に戻される。
When the bypass AC power supply 6 is restored to a healthy state, the N semiconductor switches 23 (Fig. 4) included in the N uninterruptible power supplies U1 to UN (Fig. 1) are turned on, and in each uninterruptible power supply U, AC power is supplied from the bypass AC power supply 6 to the load 8 via the reactor 21 and semiconductor switch 23, and each power module P is returned to a standby state.
図8は、本実施の形態の比較例となる無停電電源システムの要部を示す回路ブロック図であって、図4と対比される図である。図8を参照して、比較例が本実施の形態と異なる点は、リアクトル21が除去され、半導体スイッチ23の一方端子がバイパス端子T1に直接接続されている点である。
FIG. 8 is a circuit block diagram showing the main parts of an uninterruptible power supply system that is a comparative example of this embodiment, and is a diagram to be compared with FIG. 4. Referring to FIG. 8, the comparative example differs from this embodiment in that the reactor 21 is removed, and one terminal of the semiconductor switch 23 is directly connected to the bypass terminal T1.
図9は、比較例となる無停電電源システムのバイパスECO給電モードを説明するための回路ブロック図である。図9において、バイパスECO給電モード時には、N個の半導体スイッチ23がオンされ、バイパス交流電源6からN個の半導体スイッチ23の並列接続体を介して負荷8に電流ILが供給される。
FIG. 9 is a circuit block diagram for explaining the bypass ECO power supply mode of an uninterruptible power supply system serving as a comparative example. In FIG. 9, in the bypass ECO power supply mode, N semiconductor switches 23 are turned on, and a current IL is supplied from the bypass AC power supply 6 to the load 8 via the parallel connection of N semiconductor switches 23.
N個の半導体スイッチ23に流れる電流の値をそれぞれI1~INとすると、I1~INの和はILとなる。N個の半導体スイッチ23のしきい値電圧Vtが互いに一致している場合には、負荷電流ILがN個の半導体スイッチ23に均等に分流され、各半導体スイッチ23には負荷電流ILのN分の1の電流IL/Nが流れる。
If the values of the currents flowing through the N semiconductor switches 23 are I1 to IN, respectively, the sum of I1 to IN is IL. When the threshold voltages Vt of the N semiconductor switches 23 are the same, the load current IL is evenly distributed to the N semiconductor switches 23, and a current IL/N that is 1/N of the load current IL flows through each semiconductor switch 23.
しかし、実際には、N個の半導体スイッチ23のしきい値電圧Vtは定格値Vtcから10~30%程度の範囲内でばらつく。このため、バイパスECO給電モード時にN個の半導体スイッチ23に流れる電流の値I1~INは一定値IL/Nにならず、大きな範囲にばらつく。
However, in reality, the threshold voltages Vt of the N semiconductor switches 23 vary within a range of about 10 to 30% from the rated value Vtc. For this reason, the values of the currents I1 to IN flowing through the N semiconductor switches 23 in the bypass ECO power supply mode do not become a constant value IL/N, but vary over a large range.
図10は、比較例における半導体スイッチ23のV-I特性を例示する図である。図10において、曲線Aは、定格しきい値電圧Vtcを有する半導体スイッチ23のV-I特性を示している。曲線Bは、N個の半導体スイッチ23のうちの最小のしきい値電圧Vt1を有する半導体スイッチ23のV-I特性を示している。曲線Cは、N個の半導体スイッチ23のうちの最大のしきい値電圧Vt2を有する半導体スイッチ23のV-I特性を示している。
FIG. 10 is a diagram illustrating the VI characteristics of semiconductor switches 23 in a comparative example. In FIG. 10, curve A shows the VI characteristics of a semiconductor switch 23 having a rated threshold voltage Vtc. Curve B shows the VI characteristics of a semiconductor switch 23 having the smallest threshold voltage Vt1 among the N semiconductor switches 23. Curve C shows the VI characteristics of a semiconductor switch 23 having the largest threshold voltage Vt2 among the N semiconductor switches 23.
半導体スイッチ23の制御電圧Vを上昇させると、半導体スイッチ23に流れる電流Iは増大する。N個の半導体スイッチ23に同じ制御電圧Vaを印加すると、最小のしきい値電圧Vt1を有する半導体スイッチ23には最大の電流Ia1が流れ、最大のしきい値電圧Vt2を有する半導体スイッチ23には最小の電流Ia2が流れ、N個の半導体スイッチ23に流れる電流はIa1からIa2まで大きくばらつく。このため、大電流Ia1を安定に流すことが可能な大型で高価格の半導体スイッチ23を使用する必要があり、システムの大型化、コスト高を招くという問題がある。
When the control voltage V of the semiconductor switch 23 is increased, the current I flowing through the semiconductor switch 23 increases. When the same control voltage Va is applied to N semiconductor switches 23, the maximum current Ia1 flows through the semiconductor switch 23 having the minimum threshold voltage Vt1, and the minimum current Ia2 flows through the semiconductor switch 23 having the maximum threshold voltage Vt2, so that the current flowing through the N semiconductor switches 23 varies greatly from Ia1 to Ia2. For this reason, it is necessary to use a large, expensive semiconductor switch 23 capable of stably passing the large current Ia1, which poses the problem of an increase in the size and cost of the system.
図11は、本実施の形態に従う無停電電源システムのバイパスECO給電モードを説明するための回路ブロック図である。図11において、バイパスECO給電モード時には、N台の無停電電源装置U1~UNに含まれるN個の半導体スイッチ23がオンされ、バイパス交流電源6からN台の無停電電源装置U1~UNの並列接続体を介して負荷8に交流電力が供給される。このとき、各無停電電源装置Uは、リアクトル21および半導体スイッチ23の直列接続体を含む。
FIG. 11 is a circuit block diagram for explaining the bypass ECO power supply mode of the uninterruptible power supply system according to this embodiment. In FIG. 11, in the bypass ECO power supply mode, N semiconductor switches 23 included in N uninterruptible power supplies U1 to UN are turned on, and AC power is supplied from the bypass AC power source 6 to the load 8 via the parallel connection of the N uninterruptible power supplies U1 to UN. At this time, each uninterruptible power supply U includes a series connection of a reactor 21 and a semiconductor switch 23.
図12は、リアクトル21のV-I特性を例示する図である。図12において、リアクトル21に印加する電圧Vを上昇させると、リアクトル21に流れる電流Iは電圧Vに比例して増大する。リアクトル21は電線をコイル状に巻回したものであり、各リアクトル21のインピーダンスは調整可能である。これに対して半導体スイッチ23のしきい値電圧Vtを半導体スイッチ23の製造後に調整することはできない。このため、リアクトル21の特性ばらつきは、半導体スイッチ23のしきい値電圧Vtのばらつきに比べて充分に小さい。
FIG. 12 is a diagram illustrating the V-I characteristics of reactor 21. In FIG. 12, when the voltage V applied to reactor 21 is increased, the current I flowing through reactor 21 increases in proportion to the voltage V. Reactor 21 is an electric wire wound into a coil, and the impedance of each reactor 21 is adjustable. In contrast, the threshold voltage Vt of semiconductor switch 23 cannot be adjusted after semiconductor switch 23 is manufactured. For this reason, the characteristic variation of reactor 21 is sufficiently small compared to the variation of threshold voltage Vt of semiconductor switch 23.
図13は、本実施の形態におけるリアクトル21および半導体スイッチ23の直列接続体のV-I特性を例示する図である。曲線D,E,Fはそれぞれ曲線A,B,Cにリアクトル21のV-I特性を加算したものとなる。
FIG. 13 is a diagram illustrating the VI characteristics of a series connection of reactor 21 and semiconductor switch 23 in this embodiment. Curves D, E, and F are obtained by adding the VI characteristics of reactor 21 to curves A, B, and C, respectively.
半導体スイッチ23に印加する制御電圧Vを上昇させると、リアクトル21および半導体スイッチ23の直列接続体に流れる電流Iは増大するが、この電流Iは、リアクトル21のインピーダンスによって制限され、比較例の電流I(図10)と比べて小さくなる。
When the control voltage V applied to the semiconductor switch 23 is increased, the current I flowing through the series connection of the reactor 21 and the semiconductor switch 23 increases, but this current I is limited by the impedance of the reactor 21 and becomes smaller than the current I in the comparative example (Figure 10).
N個の半導体スイッチ23に同じ制御電圧Vaを印加すると、最小のしきい値電圧Vt1を有する半導体スイッチ23には最大の電流Ib1が流れ、最大のしきい値電圧Vt2を有する半導体スイッチ23には最小の電流Ib2が流れ、N個の半導体スイッチ23に流れる電流はIb1からIb2までばらつく。
When the same control voltage Va is applied to N semiconductor switches 23, the maximum current Ib1 flows through the semiconductor switch 23 with the minimum threshold voltage Vt1, and the minimum current Ib2 flows through the semiconductor switch 23 with the maximum threshold voltage Vt2, so that the current flowing through the N semiconductor switches 23 varies from Ib1 to Ib2.
しかし、図10および図13から分かるように、Ib2とIb1の差はIa2とIa1の差よりも小さくなる。このため、比較例に比べ、小型で低価格の半導体スイッチ23を使用することが可能となり、システムの低コスト化を図ることができる。
However, as can be seen from Figures 10 and 13, the difference between Ib2 and Ib1 is smaller than the difference between Ia2 and Ia1. Therefore, compared to the comparative example, it is possible to use a smaller, lower-cost semiconductor switch 23, which allows for lower system costs.
換言すると、比較例(図9)では、N個の半導体スイッチ23のインピーダンスZsのばらつきが大きいので、N個の半導体スイッチ23に流れる電流I1~INのばらつきが大きい。
In other words, in the comparative example (Figure 9), the impedance Zs of the N semiconductor switches 23 varies greatly, and therefore the currents I1 to IN flowing through the N semiconductor switches 23 vary greatly.
これに対して本実施の形態(図11)では、N個のリアクトル21のインピーダンスZxのばらつきは十分に小さい。したがって、N個のリアクトル21および半導体スイッチ23の直列接続体のインピーダンスZ=Zx+Zsのばらつきは、N個の半導体スイッチ23のインピーダンスZsのばらつきよりも小さくなる。よって、本実施の形態におけるN個の半導体スイッチ23に流れる電流I1~INのばらつきは、比較例におけるN個の半導体スイッチ23に流れる電流I1~INのばらつきよりも小さくなる。このため、比較例に比べ、小型で低価格の半導体スイッチ23を使用することが可能となる。
In contrast, in this embodiment (FIG. 11), the variation in impedance Zx of the N reactors 21 is sufficiently small. Therefore, the variation in impedance Z=Zx+Zs of the series connection of N reactors 21 and semiconductor switches 23 is smaller than the variation in impedance Zs of the N semiconductor switches 23. Therefore, the variation in currents I1 to IN flowing through the N semiconductor switches 23 in this embodiment is smaller than the variation in currents I1 to IN flowing through the N semiconductor switches 23 in the comparative example. For this reason, it is possible to use semiconductor switches 23 that are smaller and less expensive than those in the comparative example.
以上のように、この実施の形態では、各無停電電源装置Uがバイパス交流電源6と負荷8の間に直列接続されるリアクトル21および半導体スイッチ23を含むので、各半導体スイッチ23をオンすると、負荷電流ILはN個のリアクトル21および半導体スイッチ23の直列接続体に分流される。したがって、リアクトル21がない場合に比べ、N個の半導体スイッチ23に流れる電流I1~INの大きさのばらつきを小さく抑制することができ、半導体スイッチ23の小型化、低コスト化を図ることができる。
As described above, in this embodiment, each uninterruptible power supply U includes a reactor 21 and a semiconductor switch 23 connected in series between the bypass AC power supply 6 and the load 8, so that when each semiconductor switch 23 is turned on, the load current IL is shunted to a series connection of N reactors 21 and semiconductor switches 23. Therefore, compared to a case where there is no reactor 21, the variation in the magnitude of the currents I1 to IN flowing through the N semiconductor switches 23 can be suppressed to a small value, and the semiconductor switches 23 can be made smaller and less expensive.
今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The present invention is defined by the claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.
1 無停電電源システム、U1~UN 無停電電源装置、B1~BN バッテリ、2,CD1~CD3 電流検出器、3 通信線、4 操作部、5 制御装置、T1 バイパス端子、T2,T5 入力端子、T3,T6 直流端子、T4,T7 出力端子、6 バイパス交流電源、7 交流電源、8 負荷、11,27,34 通信部、12 演算部、13,28,35 制御部、14 報知部、20 バイパススイッチ、21,L1~L3 リアクトル、22 バイパスモジュール、P1~PM パワーモジュール、23 半導体スイッチ、24,25 サイリスタ、26 停電検出部、29 記憶部、F1~F3 ヒューズ、S1~S3 スイッチ、C1~C3 コンデンサ、31 コンバータ、DL 直流ライン、32 インバータ、33 双方向チョッパ、36 故障検出部、 41 電流指令部、42 電圧制御部、43 電流制御部、44 PWM制御部。
1 Uninterruptible power supply system, U1 to UN Uninterruptible power supply, B1 to BN Battery, 2, CD1 to CD3 Current detector, 3 Communication line, 4 Operation unit, 5 Control device, T1 Bypass terminal, T2, T5 Input terminal, T3, T6 DC terminal, T4, T7 Output terminal, 6 Bypass AC power supply, 7 AC power supply, 8 Load, 11, 27, 34 Communication unit, 12 Calculation unit, 13, 28, 35 Control unit, 14 Notification unit, 20 Bypass switch, 21, L1 ~L3 reactor, 22 bypass module, P1 to PM power module, 23 semiconductor switch, 24, 25 thyristor, 26 power failure detection unit, 29 memory unit, F1 to F3 fuses, S1 to S3 switches, C1 to C3 capacitors, 31 converter, DL DC line, 32 inverter, 33 bidirectional chopper, 36 fault detection unit, 41 current command unit, 42 voltage control unit, 43 current control unit, 44 PWM control unit.
Claims (5)
- 負荷に対して並列接続される複数の無停電電源装置を備え、
各無停電電源装置は、
第1の交流電源の健全時にオンにされ、前記第1の交流電源の停電時にオフされる半導体スイッチと、
前記第1の交流電源と前記負荷の間に前記半導体スイッチと直列接続されるリアクトルと、
前記第1の交流電源の停電時に、直流電源から供給される直流電力を交流電力に変換して前記負荷に供給する電力変換器とを含む、無停電電源システム。 A plurality of uninterruptible power supplies are connected in parallel to a load,
Each uninterruptible power supply is
a semiconductor switch that is turned on when a first AC power source is normal and that is turned off when a power failure occurs in the first AC power source;
a reactor connected in series with the semiconductor switch between the first AC power source and the load;
and a power converter that, when a power failure occurs in the first AC power supply, converts DC power supplied from a DC power supply into AC power and supplies the AC power to the load. - 前記リアクトルは、複数の前記半導体スイッチに流れる電流の大きさのばらつきを小さく抑制するために設けられている、請求項1に記載の無停電電源システム。 The uninterruptible power supply system according to claim 1, wherein the reactor is provided to reduce variation in the magnitude of the current flowing through the multiple semiconductor switches.
- 前記電力変換器は、前記第1の交流電源の健全時には、前記第1の交流電源から前記負荷に供給される交流電圧に応じた値のカウンタ電圧を前記負荷に出力することにより、前記第1の交流電源および前記負荷と電流を授受しない状態で待機する、請求項1に記載の無停電電源システム。 The uninterruptible power supply system according to claim 1, wherein the power converter, when the first AC power supply is healthy, outputs to the load a counter voltage having a value corresponding to the AC voltage supplied from the first AC power supply to the load, thereby waiting in a state in which no current is exchanged between the first AC power supply and the load.
- 前記直流電源は電力貯蔵装置を含み、
前記電力変換器は、
第2の交流電源から供給される交流電力を直流電力に変換する順変換器と、
直流電力を交流電力に変換する逆変換器とを含み、
前記第1および第2の交流電源の健全時には、前記順変換器によって生成される直流電力が前記逆変換器に供給されるとともに前記電力貯蔵装置に蓄えられ、前記逆変換器は、前記第1の交流電源から前記負荷に供給される交流電圧に応じた値のカウンタ電圧を前記負荷に出力することにより、前記第1の交流電源および前記負荷と電流を授受しない状態で待機し、
前記第1および第2の交流電源の停電時には、前記電力貯蔵装置の直流電力が前記逆変換器に供給され、前記逆変換器は、前記電力貯蔵装置から供給される直流電力を交流電力に変換して前記負荷に供給する、請求項3に記載の無停電電源システム。 the DC power source includes a power storage device;
The power converter includes:
a converter that converts AC power supplied from the second AC power source into DC power;
an inverter for converting DC power into AC power;
when the first and second AC power sources are healthy, DC power generated by the forward converter is supplied to the inverter and stored in the power storage device, and the inverter outputs a counter voltage having a value corresponding to an AC voltage supplied from the first AC power source to the load to the load, thereby standing by without supplying or receiving a current to or from the first AC power source and the load;
4. The uninterruptible power supply system according to claim 3, wherein, during a power outage of the first and second AC power sources, DC power from the power storage device is supplied to the inverter, and the inverter converts the DC power supplied from the power storage device into AC power and supplies it to the load. - 負荷電流を検出する電流検出器と、
前記電流検出器の検出結果に基づいて複数の前記電力変換器の各々が前記負荷に供給すべき分担電流を求める制御装置とをさらに備え、
各前記電力変換器は、前記第1の交流電源の停電時に、前記制御装置によって求められる分担電流を前記負荷に供給する、請求項1に記載の無停電電源システム。 a current detector for detecting a load current;
a control device that calculates a current share to be supplied to the load by each of the plurality of power converters based on a detection result of the current detector,
2. The uninterruptible power supply system according to claim 1, wherein each of the power converters supplies a current share determined by the control device to the load during a power outage of the first AC power supply.
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