CN111262500A - High-voltage variable-frequency driving equipment and driving method - Google Patents
High-voltage variable-frequency driving equipment and driving method Download PDFInfo
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- CN111262500A CN111262500A CN201811455064.5A CN201811455064A CN111262500A CN 111262500 A CN111262500 A CN 111262500A CN 201811455064 A CN201811455064 A CN 201811455064A CN 111262500 A CN111262500 A CN 111262500A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/085—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
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Abstract
A high-voltage variable frequency drive apparatus comprising: the power units are connected in cascade and used for accumulating the driving voltage generated by each power unit; and a control circuit for generating a plurality of control signals and outputting the plurality of control signals to the plurality of power cells, respectively, wherein each power cell includes: a controllable rectifier circuit for receiving an input voltage and rectifying the input voltage to output a rectified voltage; and the inverter circuit is connected to the controllable rectifying circuit and used for receiving the rectified voltage and generating a driving voltage, wherein the rectified voltage output by the controllable rectifying circuit of each power unit is equal under the control of the corresponding control signal. The purpose of controlling the output voltage and frequency can be achieved by taking the evenly-divided rectified voltage output by the controllable rectification circuit as the input of the inverter circuit and controlling the output of the cascade inverter circuit.
Description
Technical Field
The present disclosure relates to high-voltage variable-frequency drives, and more particularly, to a three-phase high-voltage variable-frequency drive apparatus and a drive method.
Background
Currently, high voltage inverter motor drive systems typically employ a phase-shifting transformer as an input. Fig. 1 schematically illustrates a prior art electrical system 100. In the conventional electrical system 100, as shown in fig. 1, a phase-shifting transformer 110 is used as an input and outputs an equal voltage for each phase. However, the phase-shifting transformer in the prior art usually has a multi-winding phase-shifting output, which not only occupies a large space, but also is expensive.
Disclosure of Invention
In view of the above, the present disclosure provides a high-voltage variable-frequency drive apparatus, including: the power units are connected in cascade and used for accumulating the driving voltage generated by each power unit; and a control circuit for generating a plurality of control signals and outputting the plurality of control signals to the plurality of power cells, respectively, wherein each power cell includes: a controllable rectifier circuit for receiving an input voltage and rectifying the input voltage to output a rectified voltage; and the inverter circuit is connected to the controllable rectifying circuit and used for receiving the rectified voltage and generating a driving voltage, wherein the rectified voltage output by the controllable rectifying circuit of each power unit is equal under the control of the corresponding control signal.
According to another embodiment of the present disclosure, there is provided a high-voltage variable-frequency driving method implemented by a high-voltage variable-frequency driving apparatus including a plurality of power units and a control circuit, the plurality of power units being connected in cascade for accumulating a driving voltage generated by each power unit, and each of the power units including a controllable rectification circuit for receiving an input voltage and rectifying the input voltage to output a rectified voltage, and an inverter circuit connected to the controllable rectification circuit for receiving the rectified voltage and generating the driving voltage, the high-voltage variable-frequency driving method including: generating, via the control circuit, a plurality of control signals; outputting the plurality of control signals to the plurality of power cells, respectively; and outputting equal rectified voltage by the controllable rectifying circuit of each power unit according to the received control signal.
According to the high-voltage variable-frequency driving device and the high-voltage variable-frequency driving method, the cascade controllable rectifying circuit is used for providing the equalized voltage, so that the use of a phase-shifting transformer in the prior art is avoided, the space occupied by an electrical system can be saved, and the cost of the electrical system is reduced; in addition, by cascading the input and output parts of the respective power cells separately, it is also possible to obtain a required high voltage to efficiently drive the load.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail embodiments of the present invention with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings, like reference numbers generally represent like parts or steps.
FIG. 1 schematically illustrates a prior art electrical system;
FIG. 2 schematically illustrates a schematic block diagram of an electrical system, according to an embodiment of the present disclosure;
FIG. 3 schematically illustrates a schematic detailed block diagram of an electrical system, according to an embodiment of the present disclosure;
FIG. 4 schematically illustrates a waveform diagram of signals associated with a power cell, in accordance with embodiments of the present disclosure;
FIG. 5 schematically illustrates a waveform diagram of a set of cascaded power cell related signals, in accordance with an embodiment of the present disclosure; and
fig. 6 schematically illustrates a flow chart of a high voltage variable frequency drive method according to an embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and advantages of the present disclosure more apparent, example embodiments according to the present disclosure will be described in detail below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely a subset of the embodiments of the present disclosure and not all embodiments of the present disclosure, with the understanding that the present disclosure is not limited to the example embodiments described herein. All other embodiments made by those skilled in the art without inventive efforts based on the embodiments of the present disclosure described in the present disclosure should fall within the scope of the present disclosure.
Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.
Fig. 2 schematically illustrates a schematic block diagram of an electrical system according to an embodiment of the present disclosure. In the electrical system 200 shown in fig. 2, a high-voltage variable frequency drive device 210, a three-phase alternating current power supply 220, and a load M are included. As shown in fig. 2, the high voltage variable frequency drive device 210 is connected to a three-phase power supply 220 to receive a three-phase alternating voltage and provide a high voltage to drive a load M (e.g., a motor).
The high voltage variable frequency drive device 210 includes a plurality of power cells, inductors, and a control circuit 280 cascaded together. The power units are connected in cascade, and the driving voltage generated by each power unit can be accumulated, so that the required high voltage can be provided for the load M.
As shown in fig. 2, for a three-phase power supply 220, the high-voltage variable-frequency driving device 210 correspondingly includes three inductors La, Lb, and Lc, and three sets of cascaded power units: a 1-An (n is a positive integer greater than 1), B1-Bn (n is a positive integer greater than 1), and C1-Cn (n is a positive integer greater than 1), and each set of cascaded power cells is connected to one of the three-phase ac power supplies through a corresponding inductor to receive An ac voltage, respectively, i.e., as shown in fig. 2, the cascaded power cells a 1-An are connected to a of the three-phase ac power supplies through An inductor La to receive An a ac voltage, the cascaded power cells B1-Bn are connected to B of the three-phase ac power supplies through An inductor Lb to receive a B ac voltage, and the cascaded power cells C1-Cn are connected to C of the three-phase ac power supplies through An inductor Lc to receive a C ac voltage.
In the high-voltage variable-frequency driving apparatus 210 of fig. 2, each power unit may have the same circuit structure, that is, each power unit may include: a controllable rectifier circuit for receiving an input voltage and rectifying the input voltage to output a rectified voltage; and the inverter circuit is connected to the controllable rectifying circuit and used for receiving the rectified voltage and generating a driving voltage. For example, taking as an example a group of power units connected to the A phase, each power unit Ai (1 ≦ i ≦ n, and i is a positive integer) includes: a controllable rectification circuit 220-i for receiving an input voltage and rectifying the input voltage to output a rectified voltage; and an inverter circuit 230-i connected to the controllable rectifier circuit for receiving the rectified voltage and generating a driving voltage. Similarly, each power cell Bi (1. ltoreq. i. ltoreq. n, and i is a positive integer) connected to the B phase includes: a controllable rectification circuit 240-i for receiving an input voltage and rectifying the input voltage to output a rectified voltage; and an inverter circuit 250-i connected to the controllable rectifying circuit for receiving the rectified voltage and generating a driving voltage. Similarly, each power cell Ci (1 ≦ i ≦ n, and i is a positive integer) connected to the C phase includes: a controllable rectifier circuit 260-i for receiving an input voltage and rectifying the input voltage to output a rectified voltage; and an inverter circuit 270-i connected to the controllable rectifier circuit for receiving the rectified voltage and generating a driving voltage. In one embodiment, the controllable rectifying circuit in each power unit receives the input voltage and generates an evenly divided rectified voltage on each bus unit along with the input voltage, and accordingly, in one embodiment, the rectified voltage generated by the corresponding controllable rectifying circuit can be represented by a bus capacitor voltage.
In one embodiment, the control circuit 280 is connected to the plurality of cascaded power cells for generating a plurality of control signals and outputting the plurality of control signals to the plurality of power cells, respectively. Specifically, as shown in fig. 2, the control circuit 280 is connected to the power cells a1 to An, B1 to Bn, and C1 to Cn connected in cascade, generates a plurality of control signals CTRA1 to CTRAn, CTRB1 to CTRBn, and CTRC1 to CTRCn, and outputs the control signals to the corresponding power cells a1 to An, B1 to Bn, and C1 to Cn, respectively. For example, the control circuit outputs a control signal CTRA1 to power cell a1, a control signal CTRA2 to power cell a2, and a control signal CTRAn to power cell An. Similarly, the control circuit 208 outputs control signals CTRB1 to CTRBN to the power cells B1 to Bn, respectively, and outputs control signals CTRC1 to CTRCN to the power cells C1 to Cn, respectively.
In one embodiment, the rectified voltages output by the controllable rectifying circuit of each power cell are equal under the control of the corresponding control signal. That is, for each of power cells a 1-An, each of the controllable rectifier circuits 220-i generates An equal rectified voltage Va, in one embodiment (V ═ V) under the control of a corresponding control signal CTRAiA1+VA2+…+VAn) N, wherein, VAiThe rectified voltage is output by a controllable rectifying circuit of a power unit Ai connected to the phase A of the three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with the phase A of the power supply. Similarly, for each power cell B1-Bn, each of the controllable rectifier circuits 240-i generates an equal rectified voltage Vb, in one embodiment (V ═ V @, under control of the corresponding control signal CTRBiB1+VB2+…+VBn) N, wherein, VBiThe rectified voltage is output by a controllable rectifying circuit of a power unit Bi connected to the phase B of the three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with the phase B of the power supply; for each of the power cells C1-Cn, each of the controllable rectifier circuits 260-i generates an equal rectified voltage Vc, under control of a corresponding control signal CTRCi, in one embodiment (V ═ in one embodimentC1+VC2+…+VCn) N, wherein, VCiThe rectified voltage is output by a controllable rectifying circuit of a power unit Ci connected to the C phase of a three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with the C phase of the power supply.
An inverter circuit in each power unit receives the rectified voltage output by the controllable rectifying circuit, and inverts the received rectified voltage to generate a driving voltage. At the output of the power cells, each power cell accumulates the driving voltage by cascade connection to provide the required high driving voltage for the load M.
Advantageously, by using a controllable rectifier in each power unit, the equalized voltage can be provided for the corresponding inverter circuit, and the use of a phase-shifting transformer in the prior art is avoided, so that the space occupied by the system is saved and the cost of the system is saved under the condition that the equalized voltage can be conveniently provided.
The high voltage variable frequency drive system 210 will be described in detail below in conjunction with fig. 3. Fig. 3 schematically illustrates a schematic detailed block diagram of an electrical system 200 according to an embodiment of the present disclosure. The same reference numerals in fig. 3 as in fig. 2 denote the same components. Since the group of cascaded cells connected to each phase of the power supply has the same circuit structure and connection manner, for the sake of simplicity, only the group of power cells (a 1-An) connected to the a phase of the three-phase power supply 220 will be described as An example; it should be understood that the description of the group of power cells a 1-An applies equally to the power cells B1-Bn and C1-Cn connected to the B-phase and C-phase of the power supply.
As shown in FIG. 3, each of the power cells A1-An includes a controllable rectifier circuit 220-i and An inverter circuit 230-i. Wherein each controllable rectifier circuit 220-i comprises an Insulated Gate Bipolar Transistor (IGBT) rectifier circuit for receiving an input voltage and rectifying said input voltage to output an equal rectified voltage. Taking the controllable rectification circuit 220-1 of the power cell a1 at a first end (e.g., top) of the cascaded plurality of power cells as an example, the controllable rectification circuit 220-1 includes four IGBTs S1-S4 forming a bridge rectification circuit, voltage dividing resistors R1 and R2, and bus capacitors C1 and C2 for providing dc filtering, and in one embodiment, the rectified voltage may be represented as a bus capacitor voltage. The inverter circuit 230-1 includes a bridge rectifier circuit formed of four IGBTs. The controllable rectification circuit and the inverter circuit in the remaining power units all have the same structure (as shown in fig. 3), and for the sake of brevity, the description thereof is omitted.
In one embodiment, as shown in fig. 3, the first input terminal I11 of the controllable rectification circuit 220-1 of the power unit a1 at the first end (e.g., the top) of the cascaded plurality of power units a 1-An is connected to one phase (e.g., phase a) of the three-phase ac voltage through the inductor La, and the second input terminal I12 is connected to one input terminal of the controllable rectification circuit of the subsequent power unit a2 (e.g., the first input terminal I21 of the power unit a 2).
Further, the second input terminal In2 of the controllable rectification circuit 220-n of the power cell An at the second end (e.g., bottom) among the cascaded plurality of power cells a 1-An is connected with the corresponding input terminal (e.g., second input terminal) of the controllable rectification circuit of the power cell (e.g., Bn and Cn) at the second end (e.g., bottom) of the cascaded power cells (e.g., B1-Bn and C1-Cn) for the remaining phases In the three-phase alternating voltage, as shown In fig. 3, which are all connected at the common point P1.
Furthermore, when there are also intermediate power cells Aj (1< j < n, and j is a positive integer) between the first end (e.g., top) and the second end (e.g., bottom) of the cascaded power cells a 1-An, then the first input (Ij1) of the controllable rectifier circuit of each intermediate power cell Aj is connected to one input (e.g., the second input I (j-1)2) of the controllable rectifier circuit of the previous power cell a (j-1), and the second input (Ij2) is connected to one input (e.g., the first input I (j +1)1) of the controllable rectifier circuit of the next power cell a (j + 1).
By cascading the input terminals of the controllable rectifier circuits, ac high voltage can be directly input to the cascaded controllable rectifier circuits, so that the controllable rectifier circuits can reduce input harmonics following the input voltage phase and generate equal bus voltages (i.e., rectified voltages) on each power cell.
For the output part of the power unit, a first output terminal (O11) of the inverter circuit 230-1 of the power unit a1 at a first end (e.g., top) among the cascaded plurality of power units a 1-An is connected to the load M to drive the load M, and a second output terminal (O12) is connected to one output terminal (e.g., the first output terminal O21) of the inverter circuit 230-2 of the subsequent power unit a 2.
Further, the second output terminal (On2) of the controllable rectification circuit 230-n of the power cell An at the second end (e.g., bottom) among the cascaded plurality of power cells a 1-An is connected with the corresponding output terminal (e.g., second output terminal) of the inverter circuit of the power cells (e.g., Bn and Cn) at the second end (e.g., bottom) of the cascaded power cells (e.g., B1-Bn and C1-Cn) for the remaining phases in the three-phase alternating voltage, as shown in fig. 3, and these input terminals are all connected at the common point P2.
In addition, when there are intermediate power units Aj (1< j < n, and j is a positive integer) between the first end (e.g., the top) and the second end (e.g., the bottom) of the cascaded power units a 1-An, then the first output terminal Oj1 of the inverter circuit 230-j of each intermediate power unit Aj is connected to one output terminal (e.g., the second output terminal O (j-1)2) of the inverter circuit 230- (j-1) of the previous power unit a (j-1), and the second output terminal Oj2 is connected to one output terminal (e.g., the first output terminal O (j +1)1) of the inverter circuit 230- (j +1) of the next power unit a (j + 1).
By the cascade connection of the output parts, the driving voltages of the outputs of the inverter circuits of the respective power units can be accumulated together to generate a high driving voltage to drive the load M.
The connection relationships between the input and output portions of power cells A1-An are equally applicable to power cells B1-Bn and power cells C1-Cn, and are not described herein for brevity. It will be appreciated by those skilled in the art that similar connections between the input and output sections are equally applicable for the cascaded power cells B1-Bn and C1-Cn for the remaining phases of the three-phase power supply.
Returning to the power cells connected to phase a, the controllable rectifier circuit in each of power cells a 1-An receives the control signal from control circuit 280 and outputs An equal rectified voltage based on the control signal. Similarly, the controllable rectifier circuit in each of the power cells B1-Bn and C1-Cn also correspondingly receives control signals from the control circuit 280 and outputs an equal rectified voltage based on the control signals.
In the following, a specific procedure of the controllable rectifier circuit outputting an equal rectified voltage under control of the control signal will be described in connection with fig. 4. Fig. 4 schematically illustrates a waveform diagram of a correlation signal of one power cell a1 according to an embodiment of the present disclosure. It should be understood by those skilled in the art that the waveform diagram of the signals in fig. 4 is also applicable to other power cells.
As shown in FIG. 4, VBUSThe CTRA1 is a control signal generated by the control circuit 280, and the control signal CTRA1 is a Pulse Width Modulation (PWM) signal and is output to the controllable rectification circuit 220-1 of the power unit a1, wherein the control signal CTRA1 is a voltage across the bus capacitor C1 of the power unit a1, which may represent a rectified voltage output by the corresponding controllable rectification circuit 220-1. In one embodiment, controlControl circuit 280 detects the rectified voltage output by the corresponding controllable rectifier circuit (i.e., represented as voltage V across bus capacitor C1)BUS) And comparing the detected rectified voltage with a specific voltage, and adjusting the duty ratio of the corresponding PWM control signal according to the comparison result so as to control the rectified voltage output by the controllable rectifying circuit of each power unit.
Specifically, in one embodiment, taking the example shown in fig. 4 as an example, the control circuit 280 outputs the control signal CTRA1 to the controllable rectification circuit 220-1 (e.g., to the control terminal of the IGBT S1) in the corresponding power cell a1, thereby controlling the output voltage of the controllable rectification circuit 220-1 to be maintained at a specific voltage value. Further, the control circuit 280 also performs similar control on the controllable rectification circuits in the remaining power units through the control signal, so as to realize that the rectified voltage output by each controllable rectification circuit is equal to realize voltage sharing.
Taking the power unit a1 as an example, when the output rectified voltage of the controllable rectifying circuit 220-1 therein is greater than a specific voltage value, the control circuit 280 decreases the duty cycle of the control signal CTRA1 to make the rectified voltage decrease to the specific voltage value; when the output rectified voltage of the controllable rectifier circuit 220-1 therein is smaller than a specific voltage value, the control circuit 280 increases the duty cycle of the control signal CTRA1 to increase the rectified voltage to the specific voltage value, so that the rectified voltage output by the controllable rectifier circuit in the power unit a1 is equal to the specific voltage value. Further, the controllable rectifying circuits in the rest power units can output equal rectified voltage through similar control of the control circuit on the controllable rectifying circuits in the rest power units, and therefore voltage sharing is achieved.
In one embodiment, for a group of power cells connected to each phase power supply, the corresponding specific voltage value is an average of rectified voltages output by each controllable rectifier. For example, for a group of power cells a1 to An connected to An a-phase power supply, the corresponding specific voltage Va is (V)A1+VA2+…+VAn) N, wherein, VAiFor rectified current output from a controllable rectifying circuit of a power unit Ai connected to the A phase of a three-phase AC supplyAnd voltage, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with A of the power supply. Similarly, for each power cell B1-Bn, the corresponding particular voltage Vb is equal to (V ═ VB1+VB2+…+VBn) N, wherein, VBiThe rectified voltage is output by a controllable rectifying circuit of a power unit Bi connected to the phase B of the three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with the phase B of the power supply; for each of the power cells C1 to Cn, the corresponding specific voltage Vc is (V)C1+VC2+…+VCn) N, wherein, VCiThe rectified voltage is output by a controllable rectifying circuit of a power unit Ci connected to the C phase of a three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with the C phase of the power supply.
Taking the signal waveform shown in FIG. 4 as an example, when the bus capacitor voltage VBUSEqual to the corresponding specific voltage Va, for example, during the period from time T0 to time T1 in fig. 4, the control circuit 280 generates a PWM signal having a pulse with a width d. At time T1, bus capacitor voltage VBUSIncreased and greater than a certain voltage value Va. In response, the control circuit 280 decreases the duty ratio of the control signal CTRA1 at the next switching time T2, generating the control signal CTRA having a width d1(d 1)<d) To reduce the rectified voltage and to reduce said rectified voltage to a certain voltage value Va. The switching time T2 corresponds to the carrier switching frequency, i.e. to the period of the carrier switching. At time T3, control circuit 280 detects VBUSIs reduced and is less than a specific voltage value VaAt this time, the control circuit 280 increases the duty ratio of the control signal CTRA1 at the next switching time T4 to generate the control signal CTRA having the width d2(d 2)>d) To increase the rectified voltage and to increase the rectified voltage to a certain voltage value Va. The switching time T4 corresponds to the carrier switching frequency, i.e., to the period of the carrier switching.
By comparing the bus capacitor voltage of one power unit with the average value of the rectified voltages output by the controllable rectifying circuits in the power units cascaded in the same group, the bus capacitor voltage (namely, the rectified voltage) can be dynamically adjusted in real time and is equal to the average value of all the rectified voltages of the power units cascaded in the same group, so that the power units cascaded in the same group realize voltage balance.
In addition, fig. 4 illustrates a waveform of the control signal received by the power unit a 1. For a group of power units, e.g., power units a 1-An, connected to one phase of a three-phase power supply, each power unit Ai receives a control signal with a particular phase shift Δ ps therebetween, e.g., Δ ps ═ 360 °/n (n is the number of power units in the group).
Fig. 5 schematically illustrates a waveform diagram of a set of cascaded power cells a 1-An related signals according to An embodiment of the disclosure. The signal waveforms in FIG. 5 are for the case where 8 power cells A1-A8 are included in a group of power cells. The signal waveforms a 1-A8 in fig. 5 are the drive voltages of the outputs of the power cells a 1-A8, respectively, and V is the voltage at the first output O11 of the top power cell a1, i.e., the total output voltage of the cascaded power cells. Although described in connection with power cells A1-An in FIG. 5, it should be understood by those skilled in the art that the signal waveforms of FIG. 5 are equally applicable to the groups of power cells connected to the remaining phases of the three-phase power supply, e.g., power cells B1-Bn and C1-Cn.
Fig. 6 schematically illustrates a flow chart of a high voltage variable frequency drive method according to an embodiment of the present disclosure. Although specific steps are disclosed in fig. 6, these steps are for illustration only. The inventive idea can be used to perform other steps or steps that are evolved from the specific steps in fig. 6. The exemplary operations of fig. 6 may be performed by a high voltage variable frequency drive device 210 as in fig. 2 and 3. Taking the high-voltage variable-frequency driving device 210 for the three-phase power supply in fig. 2 and 3 as An example, the high-voltage variable-frequency driving device 210 includes inductors La to Lc, a control circuit 280, and a plurality of power units a1 to An, B1 to Bn and C1 to Cn.
For the connection of the input portions of the respective power units, the first input terminal of the controllable rectification circuit of the power unit at the first end portion among the cascaded plurality of power units is connected to one input terminal of the three-phase alternating-current power supply through an inductor, the second input terminal is connected to one input terminal of the controllable rectification circuit of the subsequent power unit, the second input terminal of the controllable rectification circuit of the power unit at the second end portion among the cascaded plurality of power units is connected to the corresponding input terminal of the controllable rectification circuit of the power unit at the second end portion of the cascaded power unit for the remaining phases among the three-phase alternating-current power supply, and when there is also an intermediate power unit between the first end portion and the second end portion of the cascaded power unit, the first input terminal of the controllable rectification circuit of each intermediate power unit is connected to one input terminal of the controllable rectification circuit of the preceding power unit, the second input is connected to an input of the controllable rectifier circuit of the subsequent power unit.
For the connection of the output parts of the respective power units, a first output terminal of the inverter circuit of the power unit at a first end portion among the cascaded plurality of power units is connected to a load to drive the load, a second output terminal is connected to one output terminal of the inverter circuit of the subsequent power unit, a second output terminal of the controllable rectifier circuit of the power unit at a second end portion among the cascaded plurality of power units is connected to a corresponding output terminal of the inverter circuit of the power unit at the second end portion of the cascaded power unit for the remaining respective phases in the three-phase alternating current power supply, when there is also an intermediate power cell between the first and second ends of the cascaded power cells, the first output terminal of the inverter circuit of each intermediate power unit is connected to an output terminal of the inverter circuit of the previous power unit, and the second output terminal is connected to an output terminal of the inverter circuit of the next power unit.
In step S610, a plurality of control signals are generated by the control circuit 280. In one embodiment, control circuit 280 generates control signals for the plurality of PWM based on the modulation voltage and the carrier voltage. For example, for the three-phase power supplies shown in fig. 2 and 3, the control circuit 280 generates control signals CTRA1 to CTRAn, CTRB1 to CTRBn, and CTRC1 to CTRCn for each phase, respectively.
In step S620, the control circuit 280 outputs a plurality of control signals to the plurality of power cells, respectively. In one embodiment, taking a three-phase power supply as An example, the control circuit 280 outputs the generated control signals CTRA 1-CTRAN, CTRB 1-CTRBN, and CTRC 1-CTRCN for each phase to the power cells A1-An, B1-Bn, and C1-Cn, respectively, for controlling each controllable rectifier circuit in each power cell.
In step S630, an equal rectified voltage is output by the controllable rectifying circuit of each power cell according to the received control signal. For example, for each power unit of an a-phase power supply used in a three-phase power supply, the voltage output by its corresponding controllable rectification circuit is the average value Va of the rectified voltages output by the controllable rectification circuits of the same group of cascaded power units, where Va ═ V (V in one embodiment)A1+VA2+…+VAn) N, wherein, VAiThe rectified voltage is output by a controllable rectifying circuit of a power unit Ai connected to the phase A of the three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with the phase A of the power supply. Similarly, for each power cell B1-Bn, the voltage output by its corresponding controllable rectifier circuit has a particular value Vb, which in one embodiment is (V ═ V)B1+VB2+…+VBn) N, wherein, VBiThe rectified voltage is output by a controllable rectifying circuit of a power unit Bi connected to the phase B of the three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of cascaded power units connected with the phase B of the power supply; for each power cell C1-Cn, the voltage output by its corresponding controllable rectifying circuit is Vc, which in one embodiment is (V ═ CC1+VC2+…+VCn) N, wherein, VCiThe rectification voltage is output by a controllable rectification circuit of a power unit Ci connected to the C phase of a three-phase alternating current power supply, wherein i is more than or equal to 1 and less than or equal to n, and n is the number of rectification circuits of the cascaded power units connected with the C phase of the power supply.
In one embodiment, the rectified voltage output by each controllable rectification circuit (e.g., represented as bus capacitor voltage V) is detected by control circuit 280BUS) (ii) a The detected rectified voltage VBUSWith a particular voltage (e.g. the mother of the same group of cascaded power cells)Line voltage average) for comparison; and according to the comparison result, adjusting the duty ratio of the corresponding PWM control signal to control the rectified voltage output by the controllable rectifying circuit of each power unit. In one embodiment, when the rectified voltage V is detectedBUSWhen the voltage is greater than the specific voltage, the control circuit 280 decreases the duty ratio of the corresponding PWM signal to decrease the corresponding rectified voltage; when the rectified voltage V is detectedBUSWhen the voltage is less than the specific voltage, the control circuit 280 increases the duty ratio of the corresponding PWM signal to increase the corresponding rectified voltage, thereby realizing that the controllable rectifying circuit of each power unit outputs the same rectified voltage. In one embodiment, the specific voltage may be an average value of rectified voltages output by controllable rectification circuits of the same group of cascaded power cells.
The foregoing describes the general principles of the present disclosure in conjunction with specific embodiments, however, it is noted that the advantages, effects, etc. mentioned in the present disclosure are merely examples and are not limiting, and they should not be considered essential to the various embodiments of the present disclosure. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the disclosure is not intended to be limited to the specific details so described.
The block diagrams of devices, apparatuses, systems referred to in this disclosure are only given as illustrative examples and are not intended to require or imply that the connections, arrangements, configurations, etc. must be made in the manner shown in the block diagrams. These devices, apparatuses, devices, systems may be connected, arranged, configured in any manner, as will be appreciated by those skilled in the art. Words such as "including," "comprising," "having," and the like are open-ended words that mean "including, but not limited to," and are used interchangeably therewith. The words "or" and "as used herein mean, and are used interchangeably with, the word" and/or, "unless the context clearly dictates otherwise. The word "such as" is used herein to mean, and is used interchangeably with, the phrase "such as but not limited to".
The flowchart of steps in the present disclosure and the above description of the methods are only given as illustrative examples and are not intended to require or imply that the steps of the various embodiments must be performed in the order given, some steps may be performed in parallel, independently of each other or in other suitable orders. Additionally, words such as "thereafter," "then," "next," etc. are not intended to limit the order of the steps; these words are only used to guide the reader through the description of these methods.
It is also noted that in the apparatus and methods of the present disclosure, the components or steps may be broken down and/or recombined. These decompositions and/or recombinations are to be considered equivalents of the present disclosure.
The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. While a number of example aspects and embodiments have been discussed above, those of skill in the art will recognize certain variations, modifications, alterations, additions and sub-combinations thereof.
Claims (12)
1. A high-voltage variable frequency drive apparatus comprising:
the power units are connected in cascade and used for accumulating the driving voltage generated by each power unit; and
a control circuit for generating a plurality of control signals and outputting the plurality of control signals to the plurality of power cells, respectively,
wherein each power cell comprises:
a controllable rectifier circuit for receiving an input voltage and rectifying the input voltage to output a rectified voltage; and
an inverter circuit connected to the controllable rectifier circuit for receiving the rectified voltage and generating a drive voltage,
under the control of the corresponding control signal, the rectified voltage output by the controllable rectifying circuit of each power unit is equal.
2. The high-voltage variable-frequency drive device according to claim 1, wherein the cascaded plurality of power cells are connected with one of three-phase alternating current power supplies through an inductor to receive the input voltage.
3. The high-voltage variable frequency drive apparatus according to claim 1,
the first input end of the controllable rectifying circuit of the power unit at the first end part in the cascaded plurality of power units is connected with one input end of the three-phase alternating current power supply through an inductor, the second input end of the controllable rectifying circuit of the power unit is connected with one input end of the controllable rectifying circuit of the subsequent power unit,
a second input of the controllable rectification circuit of the power cell at the second end of the cascaded plurality of power cells is connected with a corresponding input of the controllable rectification circuit of the power cell at the second end of the cascaded power cell for the remaining phases in the three-phase alternating current power supply, and
when an intermediate power unit is further provided between the first end and the second end of the cascaded power units, the first input end of the controllable rectifying circuit of each intermediate power unit is connected with one input end of the controllable rectifying circuit of the previous power unit, and the second input end is connected with one input end of the controllable rectifying circuit of the next power unit.
4. The high-voltage variable frequency drive apparatus according to claim 1,
a first output terminal of the inverter circuit of the power unit at a first end among the cascaded plurality of power units is connected to a load to drive the load, a second output terminal is connected to one output terminal of the inverter circuit of the subsequent power unit,
a second output terminal of the controllable rectification circuit of the power unit at the second end portion among the cascaded plurality of power units is connected with a corresponding output terminal of the inverter circuit of the power unit at the second end portion of the cascaded power units for the remaining respective phases in the three-phase alternating current power supply,
when an intermediate power unit is further arranged between the first end part and the second end part of the cascaded power units, the first output end of the inverter circuit of each intermediate power unit is connected with one output end of the inverter circuit of the previous power unit, and the second output end of the inverter circuit of the next power unit is connected with one output end of the inverter circuit of the next power unit.
5. The high-voltage variable-frequency drive apparatus according to claim 1, wherein the plurality of control signals include a plurality of PWM control signals, and the control circuit detects the rectified voltage output by each of the controllable rectification circuits, compares the detected rectified voltage with a specific voltage, and adjusts a duty ratio of the corresponding PWM control signal according to the comparison result to control the rectified voltage output by the controllable rectification circuit of each power unit.
6. The high-voltage variable frequency drive apparatus according to claim 1, wherein the controllable rectification circuit in each power cell comprises an insulated gate bipolar transistor rectification circuit.
7. A high-voltage variable-frequency drive method implemented by a high-voltage variable-frequency drive apparatus including a plurality of power cells connected in cascade for accumulating a drive voltage generated by each power cell, and each of the power cells including a controllable rectification circuit for receiving an input voltage and rectifying the input voltage to output a rectified voltage, and an inverter circuit connected to the controllable rectification circuit for receiving the rectified voltage and generating a drive voltage, the high-voltage variable-frequency drive method comprising:
generating, via the control circuit, a plurality of control signals;
outputting the plurality of control signals to the plurality of power cells, respectively; and
and outputting equal rectified voltage by the controllable rectifying circuit of each power unit according to the received control signal.
8. The high-voltage variable-frequency driving method according to claim 7, wherein the cascaded plurality of power units are connected with one of three-phase alternating-current power supplies through an inductor to receive the input voltage.
9. The high-voltage variable frequency drive method according to claim 7,
the first input end of the controllable rectifying circuit of the power unit at the first end part in the cascaded plurality of power units is connected with one input end of the three-phase alternating current power supply through an inductor, the second input end of the controllable rectifying circuit of the power unit is connected with one input end of the controllable rectifying circuit of the subsequent power unit,
a second input of the controllable rectification circuit of the power cell at the second end of the cascaded plurality of power cells is connected with a corresponding input of the controllable rectification circuit of the power cell at the second end of the cascaded power cell for the remaining phases in the three-phase alternating current power supply, and
when an intermediate power unit is further provided between the first end and the second end of the cascaded power units, the first input end of the controllable rectifying circuit of each intermediate power unit is connected with one input end of the controllable rectifying circuit of the previous power unit, and the second input end is connected with one input end of the controllable rectifying circuit of the next power unit.
10. The high-voltage variable frequency drive method according to claim 7,
a first output terminal of the inverter circuit of the power unit at a first end among the cascaded plurality of power units is connected to a load to drive the load, a second output terminal is connected to one output terminal of the inverter circuit of the subsequent power unit,
a second output terminal of the controllable rectification circuit of the power unit at the second end portion among the cascaded plurality of power units is connected with a corresponding output terminal of the inverter circuit of the power unit at the second end portion of the cascaded power units for the remaining respective phases in the three-phase alternating current power supply,
when an intermediate power unit is further arranged between the first end part and the second end part of the cascaded power units, the first output end of the inverter circuit of each intermediate power unit is connected with one output end of the inverter circuit of the previous power unit, and the second output end of the inverter circuit of the next power unit is connected with one output end of the inverter circuit of the next power unit.
11. The high voltage variable frequency drive method of claim 7, the plurality of control signals comprising a plurality of PWM control signals, and further comprising:
detecting, by the control circuit, a rectified voltage output by each of the controllable rectification circuits;
comparing the detected rectified voltage to a specified voltage; and
and according to the comparison result, adjusting the duty ratio of the corresponding PWM control signal to control the rectified voltage output by the controllable rectifying circuit of each power unit.
12. The high-voltage variable-frequency drive method according to claim 7, wherein the controllable rectifying circuit in each power unit comprises an insulated gate bipolar transistor rectifying circuit.
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