Power conversion control device

Abstract

To provide a power supply device that equalizes a current sharing of a unit chopper.SOLUTION: A power supply device according to an embodiment, comprises a plurality of unit choppers having an upper-stage circuit and a lower-stage circuit that are series conducted between a positive electrode and a negative electrode, a first capacitor C1 that is parallely connected to the upper-stage circuit, and a second capacitor C2 that is parallely connected to the lower-stage circuit. Each of the upper-stage circuit and the lower-stage circuit comprises at least one switching element, and comprises: a multiple arrangement chopper circuit in which each of an output end of the upper-stage circuit and an output end of the lower-stage circuit is electrically and mutually connected while electrically and mutually connecting each of the positive electrode and the negative electrode of a plurality of unit choppers 21-2n; an arithmetic part 31-3n that calculates a conduction ratio of each unit chopper by using an output current value of the upper-stage circuit and an output current value of the lower-stage circuit; and a generation part 41-4n that generates a signal for controlling an operation of each switching element of the upper-stage circuit and the lower-stage circuit by using the conductive ratio.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a power converter controller. [Background technology]

[0002] Chopper circuits are used as power supply devices to supply an appropriate voltage from a DC power source to a load. Chopper circuits adjust the output voltage by switching a semiconductor switching element, and have the ability to adjust voltage quickly. However, when using a chopper circuit, the current capacity of the semiconductor element limits the capacity of the power supply device.

[0003] Therefore, it has been proposed to increase the capacity of a power supply by connecting multiple chopper circuits in parallel. In this case, for example, a configuration has been proposed in which a reactor is connected to the output of each chopper circuit and the output of the multiple chopper circuits is connected in parallel via the reactor. Furthermore, by detecting the current flowing through each reactor and controlling the current flowing through the reactor for each chopper circuit, it is possible to equalize the current sharing among the chopper circuits. This allows the required power to be supplied with the minimum number of choppers connected in parallel, and also makes it possible to equalize the load of each chopper circuit.

[0004] On the other hand, the size of the reactor connected to the output of each chopper circuit is restricted by the switching frequency of each chopper circuit, making it difficult to miniaturize.For example, if the voltage harmonics applied to the reactor could be reduced without increasing the switching frequency of the semiconductor switching elements of the chopper circuit, the reactor could be made smaller.Conventionally, methods have been proposed to reduce the harmonic voltages generated in multiple chopper circuits connected in series. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 1997-215322 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-188655 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-96969 Summary of the Invention [Problem to be solved by the invention]

[0006] A control method has been proposed that equalizes the duties of each chopper circuit by using the value of the current flowing through the reactor connected to the positive side of the chopper circuit. However, it has been difficult to apply this control method to a power supply device in which the outputs of chopper circuits, each of which has multiple unit circuits connected in series, are connected in parallel.

[0007] The embodiments of the present invention have been made in consideration of the above circumstances, and have an object to provide a power supply device in which a number of unit choppers are connected in parallel, and which equalizes the current sharing of the unit choppers. [Means for solving the problem]

[0008] a first capacitor connected in parallel with the upper stage circuit, a second capacitor connected in parallel with the lower stage circuit, a first reactor connected to an output terminal of the upper stage circuit, and a second reactor connected to an output terminal of the lower stage circuit, each of the upper stage circuit and the lower stage circuit having at least one switching element, electrically connecting the positive electrodes and the negative electrodes of the plurality of unit choppers to each other and electrically connecting the output terminals of the upper stage circuit and the output terminals of the lower stage circuit to each other; a duty calculation unit that calculates the duty of the unit chopper using the output current value of the upper stage circuit and the output current value of the lower stage circuit; and a signal generation unit that generates a signal that controls operation of the switching elements of the upper stage circuit and the lower stage circuit based on the duty. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of the configuration of a power supply device according to a first embodiment. [Figure 2] FIG. 2 is a diagram for explaining an example of the effect of the power supply device of one embodiment. [Figure 3] FIG. 3 is a diagram schematically illustrating a modified example of the power supply device of the first embodiment. [Figure 4] FIG. 4 is a diagram schematically illustrating an example of the configuration of the power supply device according to the second embodiment. [Figure 5] FIG. 5 is a block diagram showing an outline of an example of the configuration of the duty calculation unit and the gate signal generation unit of the power supply device shown in FIG. [Figure 6] FIG. 6 is a diagram for explaining an example of the operation of the power supply device of the comparative example. [Figure 7] FIG. 7 is a diagram for explaining an example of the operation of the power supply device according to the second embodiment. [Figure 8] FIG. 8 is a diagram for explaining an example of the operation of the power supply device according to the third embodiment. [Figure 9] FIG. 9 is a diagram schematically illustrating an example of the configuration of a power supply device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the power supply device according to the embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically illustrating an example of the configuration of a power supply device according to a first embodiment. The power supply device of this embodiment is connected between a DC power supply 10 and a load 50, and includes a multi-parallel chopper circuit and a control circuit CTR. The multi-parallel chopper circuit includes a plurality of unit choppers 21-2n. The plurality of unit choppers 21-2n are connected in parallel to the DC power supply 10 and the load 50.

[0011] Each of the unit choppers 21-2n includes a DC circuit, and an upper stage circuit and a lower stage circuit connected in series between the positive electrode P and the negative electrode N of the DC power supply 10. The DC circuit includes capacitors C1 and C2 connected in series between the positive terminal P and negative terminal N of the DC power supply.

[0012] The upper stage circuit includes semiconductor switching elements S1 and S2 connected in parallel to a capacitor (first capacitor) C1, and reactors (first reactors) L11-Ln1, which are inductance elements. The upper stage circuit is electrically connected to a load 50 via the reactors L11-Ln1 between the semiconductor switching elements S1 and S2 (output terminals). That is, the portion between the semiconductor switching elements S1 and S2 is electrically connected to one terminal of the reactors L11-Ln1. The other terminal (positive output terminal) of the reactors L11-Ln1 is electrically connected to the load 50.

[0013] The lower-stage circuit includes semiconductor switching elements S3 and S4 connected in parallel to a capacitor (second capacitor) C2, and a reactor (second reactor) L12-Ln2, which is an inductance element. The lower-stage circuit is electrically connected to the load 50 via the reactor L12-Ln2 between the semiconductor switching elements S3 and S4. That is, the space between the semiconductor switching elements S3 and S4 is electrically connected to one end of the reactor L12-Ln2. The other end (negative output end) of the reactor L12-Ln2 is electrically connected to the load 50.

[0014] In the power supply device of this embodiment, the semiconductor switching elements S1-S4 include self-extinguishing elements such as IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors), and diodes connected in anti-parallel to the self-extinguishing elements. Note that the semiconductor switching elements S2 and S3 may be diodes and the semiconductor switching elements S1 and S4 may be self-extinguishing elements and diodes, or the semiconductor switching elements S2 and S3 may be self-extinguishing elements and diodes and the semiconductor switching elements S1 and S4 may be diodes.

[0015] In this embodiment, the interconnection point between the capacitor C1 and the capacitor C2 is defined as a neutral point O. The neutral points O of the plurality of unit choppers 21-2n are electrically connected to one another. The positive electrode P of each of the plurality of unit choppers 21-2n is electrically connected to the positive electrode of the DC power supply 10, and the negative electrode N is electrically connected to the negative electrode of the DC power supply 10. In addition, the positive output terminals of the plurality of unit choppers 21-2n are electrically connected to one another and to the positive input terminal of the load 50. The negative output terminals of the plurality of unit choppers 21-2n are electrically connected to one another and to the negative input terminal of the load 50. As described above, the positive electrodes, neutral point, negative electrodes, positive output terminals, and negative output terminals of the plurality of unit choppers 21-2n are interconnected to form a multi-parallel chopper circuit.

[0016] In the power supply device of this embodiment, the interconnection point of the positive poles P of the plurality of unit choppers 21-2n and the interconnection point of the negative poles N form a high-voltage side DC circuit of the multi-parallel chopper, which is connected to a DC power supply 10. The low-voltage side DC circuit is connected to a load 50 between the positive pole output terminals and negative pole output terminals of the plurality of unit choppers 21-2n. Note that the multi-parallel chopper circuit of the power supply device of this embodiment is not limited to the above configuration, and a load may be connected to the high-voltage side DC circuit of the multi-parallel chopper circuit, and a power supply may be connected to the low-voltage side DC circuit, or a power supply may be connected to both the high-voltage side and the low-voltage side to form an inter-power supply interface circuit.

[0017] The control circuit CTR outputs gate signals for the semiconductor switching elements S1-S4 to each of the plurality of unit choppers 21-2n. The control circuit CTR includes a plurality of chopper control circuits 201-20n, each of which includes a duty calculation unit 31-3n, a gate signal generation unit 41, and current sensors A11-An1 and A12-An2. Since the plurality of chopper control circuits 201-20n have the same configuration, only the chopper control circuit 201 will be described below, and descriptions of the other chopper control circuits 202-20n will be omitted.

[0018] The current sensor A11 is attached to a circuit connected between the positive output terminal of the unit chopper 21 and the load 50. The current sensor A11 detects the current output from the positive output terminal and supplies the detected value (output current value) to the duty calculation unit 31.

[0019] The current sensor A12 is attached to a circuit connected between the negative output terminal of the unit chopper 21 and the load. The current sensor A12 detects the current output from the negative output terminal and supplies the detected value (output current value) to the duty calculation unit 31.

[0020] The duty calculation unit 31 acquires the detection values ​​(output current values) detected by the current sensors A11 and A12, calculates the conduction ratio (duty) of the unit chopper 21 based on the detection values, and outputs the same to the gate signal generation unit 41.

[0021] The gate signal generating unit 41 generates a signal (gate signal) for controlling the operation of the semiconductor switching elements S1-S4 of the unit chopper 21 from the conduction ratio calculated by the duty calculating unit 31.

[0022] As described above, by detecting the current output from the positive output terminal and the current output from the negative output terminal for each of the plurality of unit choppers 21-2n and controlling each unit chopper 21-2n using the detected values, the output current of each unit chopper 21-2n can be controlled arbitrarily, and the load current can be shared equally among the plurality of unit choppers that make up the multi-parallel chopper circuit.

[0023] FIG. 2 is a diagram for explaining an example of the effect of the power supply device of one embodiment. Here, the effects of the power supply device of this embodiment will be described using as an example a power supply device equipped with a multi-parallel chopper circuit including unit chopper A and unit chopper B. Also, with regard to the current detection values ​​at the positive output terminal and negative output terminal of each unit chopper A, B, the direction in which current flows out from the positive output terminal to the load 50 side is defined as positive, and the direction in which current flows from the load 50 side to the negative output terminal is defined as positive.

[0024] Unit chopper A and unit chopper B are electrically connected to each other by the high-voltage side DC circuit and the low-voltage side DC circuit. As a result, a path for a cross current is formed between unit chopper A and unit chopper B. For example, this is a circuit loop formed by the interconnection point of the positive poles of unit chopper A and unit chopper B and the interconnection point of the positive output terminal of unit chopper A and the positive output terminal of unit chopper B.

[0025] The current flowing through the positive output terminal of unit chopper A is i aA , the current flowing through the negative output terminal is i aB Let i be the current flowing through the positive output terminal of unit chopper B. bA , the current flowing through the negative output terminal is i bB Then, the load current i load is expressed by the following equation (1) from Kirchhoff's law. Note that the direction of the current arrow in Figure 2 is positive. i load =i aA +i bA =i aB +i bB (1)

[0026] Here, for each of the unit choppers A and B, the normal mode current is the average value of the current flowing through the positive output terminal and the current flowing through the negative output terminal, and is the current component that is common to the positive pole P and the negative pole N. The normal mode current of unit chopper A is defined as i na , the normal mode current of unit chopper B is i nb The common mode current is the value obtained by dividing the difference between the current flowing through the positive output terminal and the current flowing through the negative output terminal by 2, and is the current component that differs between the positive terminal P and the negative terminal N. The common mode current of unit chopper A is expressed as i ca , the common mode current of unit chopper B is i cb These normal mode currents i na , i nb and the common mode current i ca , i cb Using these, the current flowing through the output terminals of each of the unit choppers A and B can be expressed by the following equation (2).

[0027]

number

[0028] This is because the load 50 is a two-terminal circuit and cannot pass a normal mode current component. Therefore, assuming that the common mode currents of unit chopper A and unit chopper B cancel each other out, each common mode current is defined as follows: i ca =-i cb =i c (4)

[0029] Substituting equation (4) into equation (3) gives the following equation, which then gives equation (1). iload =i na +i nb +i c -i c =i na +i nb -(i c -i c ) (5) From the above, it can be seen that there is a possibility that a common mode current component will flow through each of the unit choppers A and B under the condition that the sum of the common mode current components of the unit choppers A and B is zero.

[0030] Here, let us consider the case where each of unit choppers A and B is controlled using only the detected value of the current flowing to the positive output terminal. It is assumed that the same current command value is given to the chopper control unit to control so that the output currents of unit choppers A and B are the same in order to distribute the load current equally to unit choppers A and B. In this case, it is considered that the value of the current flowing to the positive output terminal of each of unit choppers A and B is equal between unit chopper A and unit chopper B and coincides with the current command value.

[0031] The current command for unit choppers A and B is i ref Assuming that the currents flowing to the positive output terminals of unit choppers A and B match the current commands, the currents flowing to the positive output terminals of unit choppers A and B are expressed by the following equations. i aA =i ref =i na +i c (6) i bA =i ref =i nb -i c (7)

[0032] From equations (6) and (7), the normal mode current i na , i nb The following equation is obtained: i na =i ref -i c (8) i nb =i ref +ic (9)

[0033] The normal mode current i obtained from equations (8) and (9) na , i nb Substituting this into equation (2), the current i flowing through the negative output terminals of unit choppers A and B is aB , i bB The following equation is obtained: i aB =i ref -2i c (10) i bB =i ref +2i c (11)

[0034] From the above, the current flowing through the output terminals of unit chopper A and unit chopper B is expressed by the following equation.

number

[0035] As shown above, the current i flowing through the positive output terminal aA , i bA When current control is performed using the above, the current i aA , i bA On the other hand, the current i flowing through the negative output terminal not used for current control aB , i bB This results in an imbalance between unit chopper A and unit chopper B. In other words, this means that the current at the negative output terminal cannot be controlled to an arbitrary value. The current i flowing at the negative output terminal aB , i bB If there is an imbalance, there is a possibility that the output current will be concentrated at the negative output terminal of a specific unit chopper.

[0036] current i aB , i bBpasses through the semiconductor switching elements S1-S4 that make up the unit choppers A and B, and is therefore subject to the allowable current of the semiconductor switching elements S1-S4. As a result, it may not be possible to maximize the output of the multi-parallel chopper circuit. In order to maximize the output of the multi-parallel chopper circuit, the current i flowing through the positive output terminals of the unit choppers A and B must be aA , i bA In addition, the current i flowing through the negative output terminal aB , i bB The values ​​of also need to be balanced between unit choppers A and B.

[0037] Therefore, in the power supply device of this embodiment, the control circuit CTR detects the current flowing through the positive output terminal and the current flowing through the negative output terminal of each of the multiple unit choppers 21-2n, determines the conduction rate of each of the multiple unit choppers 21-2n using each current detection value, and controls the current to realize the conduction rate, making it possible to control the current flowing through the positive output terminal and the negative output terminal to any value.

[0038] That is, according to this embodiment, it is possible to provide a power supply device in which a number of unit choppers are connected in parallel, in which the current sharing of the unit choppers is equalized.

[0039] Next, a modification of the power supply device of the first embodiment will be described in detail with reference to the drawings. FIG. 3 is a diagram schematically illustrating a modified example of the power supply device of the first embodiment. In the above-described first embodiment, a power supply device including a plurality of unit choppers 21-2n interconnected at the positive pole P, neutral point O, and negative pole N of the high-voltage side DC circuit has been described, but the configuration of the power supply device is not limited to this.

[0040] In the power supply device of this modified example, the plurality of unit choppers are connected to each other at the positive pole P and negative pole N of the high voltage side DC circuit, but are not connected to each other at the neutral point O. FIG. 3 shows a power supply device including a multi-parallel chopper circuit having a unit chopper A and a unit chopper B as an example.

[0041] In the power supply device of this modified example, unit chopper A and unit chopper B are not interconnected at neutral point O, but as shown in Fig. 3, a cross current path is formed between unit chopper A and unit chopper B, and there is a possibility that a common mode current component will flow through unit chopper A and unit chopper B. For this reason, even when a plurality of unit choppers are not interconnected at neutral point O, the output current of the unit chopper can be controlled by detecting the currents flowing through the positive output terminal and the negative output terminal as in the above-described embodiment and determining the duty ratio of each unit chopper using the respective current detection values. That is, according to this modification, it is possible to provide a power supply device in which a number of unit choppers are connected in parallel, and in which the current sharing of the unit choppers is equalized.

[0042] Next, a power supply device according to a second embodiment will be described in detail with reference to the drawings. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted. FIG. 4 is a diagram schematically illustrating an example of the configuration of the power supply device according to the second embodiment.

[0043] The power supply device of this embodiment differs from the first embodiment in the configuration of the control circuit CTR. Specifically, in this embodiment, the detection values ​​of the current sensors A11 and A12 and a current reference value (first current reference value) are input to a duty calculation unit 31 of the control circuit CTR. The current reference value may be a value that is preset in the control circuit CTR, or may be a value that is input from an external device such as a higher-level control device of the power supply device.

[0044] FIG. 5 is a block diagram showing an outline of an example of the configuration of the duty calculation unit and the gate signal generation unit of the power supply device shown in FIG. The duty calculation unit 31 includes an adder 311 , a divider 312 , a subtractor 313 , and a PI compensator 314 .

[0045] The adder 311 receives the detected value i of the current sensor A11. Aand the detected value i of the current sensor A12 B The adder 311 receives the detected value i A and the detected value i B The sum of the above is calculated and supplied to the division unit 312. The division unit 312 divides the value supplied from the addition unit 311 (detection value i A +Detection value i B ) by 2 to calculate the quotient, which is supplied to the subtraction unit 313. That is, the adder 311 and divider 312 calculate and output a normal mode current value which is the average value of the output currents of the upper and lower circuits of the unit chopper.

[0046] The current reference value and the output value of the division unit 312 are input to the subtraction unit 313. The subtraction unit 313 calculates the difference by subtracting the output value (normal mode current value) of the division unit 312 from the current reference value, and supplies the difference to the PI compensator 314. The PI compensator 314 calculates and outputs the conduction ratio of the unit chopper 21 by proportional-integral control so that the value input from the subtraction unit 313 becomes zero. The PI compensator 314 supplies the calculated conduction ratio to the gate signal generation unit 41.

[0047] The gate signal generating unit 41 includes comparison units 411 and 412 and negation units 413 and 414 . The comparator 411 receives the duty ratio value supplied from the duty calculation unit 31 and the triangular wave carrier of the upper circuit. The comparator 411 performs, for example, PWM control, compares the duty ratio value with the triangular wave carrier value, and generates and outputs a gate signal for the semiconductor switching element S1.

[0048] The gate signal of semiconductor switching element S1 output from comparison unit 411 is input to NOT operation unit 413. NOT operation unit 413 generates and outputs a signal that is the inverse of the input value. The output signal of NOT operation unit 413 is the gate signal of semiconductor switching element S2.

[0049] The comparator 412 receives the duty ratio value supplied from the duty calculation unit 31 and the triangular wave carrier of the lower circuit. The triangular wave carrier of the lower circuit is a triangular wave that is 180° phase shifted from the triangular wave carrier of the upper circuit. The comparator 412 performs, for example, PWM control, compares the duty ratio value with the triangular wave carrier value, and generates and outputs a gate signal for the semiconductor switching element S4.

[0050] The gate signal of semiconductor switching element S4 output from comparison unit 412 is input to NOT operation unit 414. NOT operation unit 414 generates and outputs a signal that is the inverse of the input value. The output signal of NOT operation unit 414 is the gate signal of semiconductor switching element S3. The configurations of the duty calculation unit 32-3n and the gate signal generation unit 42-4n are the same as those of the duty calculation unit 31 and the gate signal generation unit 41 described above.

[0051] As described above, in the power supply device of this embodiment, the duty ratio is determined so that the normal mode current value of each of the plurality of unit choppers 21-2n follows the current reference value. Also, the gate signals of the upper stage circuit and the lower stage circuit are generated using the same duty ratio value. The current reference value is the same in controlling the plurality of unit choppers 21-2n, which causes the normal mode current values ​​of the plurality of unit choppers 21-2n to approximately match, and the current flowing through the positive output terminal and the current flowing through the negative output terminal of the unit chopper 21-2n are balanced.

[0052] FIG. 6 is a diagram for explaining an example of the operation of the power supply device according to the second embodiment. Here, in the power supply device of this embodiment, when controlling a multi-parallel chopper circuit having unit choppers A and B, the gate signals of the semiconductor switching elements S1 and S4 of the unit choppers A and B, and the current (i A ), the current (i B ), the normal mode current of unit choppers A and B (i A / 2+i B / 2) and common mode current (iA / 2-i B 6 shows an example of the conduction ratio of each of unit chopper A and unit chopper B. / 2), the output voltage of unit chopper A, the output voltage of unit chopper B, the carrier waves of the upper and lower circuits, and the conduction ratio of each of unit chopper A and unit chopper B. Note that Fig. 6 shows an example in which the conduction ratio is changed at the peak of the carrier wave of the lower circuit (the trough of the carrier wave of the upper circuit).

[0053] As shown in FIG. 6, in the power supply device of this embodiment, the duty ratios of unit chopper A and unit chopper B are adjusted independently, the normal mode currents of unit chopper A and unit chopper B are approximately the same, and the output currents of unit choppers A and B can be balanced. That is, according to this embodiment, it is possible to provide a power supply device in which a number of unit choppers are connected in parallel, in which the current sharing of the unit choppers is equalized.

[0054] As described above, in the power supply device of this embodiment, the control circuit CTR sets the duty ratio of the unit chopper to the same value for the upper and lower circuits and generates gate signals for the semiconductor switching elements by comparing the triangular wave carrier with the duty ratio. Here, if the elements S2 and S3 of the unit chopper are diodes and the elements S1 and S4 are self-extinguishing elements, the control circuit CTR uses only the gate signals of the semiconductor switching elements S1 and S4. If the elements S1 and S4 are diodes and the elements S2 and S3 are self-extinguishing elements, the control circuit CTR uses only the gate signals of the semiconductor switching elements S2 and S3. In either configuration, the relationship between the output voltage and the duty ratio of the unit chopper is the same, and the operation described in FIG. 6 and the following embodiments is the same as when all the elements S1-S4 are semiconductor switching elements.

[0055] Next, a power supply device according to a third embodiment will be described in detail with reference to the drawings. The power supply device of this embodiment differs from the first and second embodiments in the configuration of the control circuit CTR. Specifically, in this embodiment, the detection values ​​of the current sensors A11 and A12, a current reference value (first current reference value), and a common mode current command value (second current reference value) are input to a duty calculation unit 31 of the control circuit CTR. Note that the current reference value and the common mode current command value may be values ​​that are preset in the control circuit CTR, or may be values ​​that are input from an external device such as a higher-level control device of the power supply device.

[0056] FIG. 7 is a block diagram showing a schematic configuration example of a duty calculation unit and a gate signal generation unit of a power supply device according to the third embodiment. The duty calculation unit 31 includes adders 311 and 319, dividers 312 and 316, subtractors 313, 315, 317 and 310, and PI compensators 314 and 318.

[0057] The adder 311 receives the detected value i of the current sensor A11. A and the detected value i of the current sensor A12 B The adder 311 receives the detected value i A and the detected value i B The sum of the above is calculated and supplied to the division unit 312. The division unit 312 divides the value supplied from the addition unit 311 (detection value i A +Detection value i B ) by 2 to calculate the quotient, which is supplied to the subtraction unit 313.

[0058] That is, the adder 311 and divider 312 calculate and output a normal mode current value which is the average value of the output currents of the upper and lower circuits of the unit chopper. The current reference value and the output value of the division unit 312 are input to the subtraction unit 313. The subtraction unit 313 calculates the difference by subtracting the output value (normal mode current value) of the division unit 312 from the current reference value, and supplies the difference to the PI compensator 314.

[0059] The PI compensator 314 calculates and outputs the components of the conduction ratio of the unit chopper 21 by proportional-integral control so that the value input from the subtraction unit 313 becomes zero. The PI compensator 314 supplies the calculated components of the conduction ratio to the addition unit 319 and the subtraction unit 310.

[0060] The subtraction unit 315 receives the detected value i of the current sensor A11. A and the detected value i of the current sensor A12 B The subtraction unit 315 receives the detected value i A From the detected value i B The difference is calculated by subtracting the difference and supplied to the division unit 316. The division unit 316 subtracts the value supplied from the subtraction unit 315 (detection value i A -detection value i B ) by 2 to calculate the quotient, which is supplied to the subtraction unit 317. That is, the subtraction unit 315 and the division unit 316 calculate and output the common mode current of the unit chopper.

[0061] The subtraction unit 317 receives as input the common mode current command value and the output value of the division unit 316. The subtraction unit 317 calculates a difference by subtracting the output value (common mode current value) of the division unit 316 from the common mode current command value, and supplies the difference to the PI compensator 318. Note that the common mode current component is a current component that circulates between the unit choppers and does not contribute to the power supplied to the load, and therefore the common mode current command value is set to zero in this embodiment.

[0062] The PI compensator 318 calculates and outputs the components of the conduction ratio of the unit chopper 21 by proportional-integral control so that the value input from the subtraction unit 317 becomes zero. The PI compensator 318 supplies the calculated components of the conduction ratio to the addition unit 319 and the subtraction unit 310. The addition unit 319 receives the conduction ratio output from the PI compensator 314 and the conduction ratio output from the PI compensator 318, calculates the sum of the input values, and outputs the sum to the gate signal generation unit 41.

[0063] The subtraction unit 310 receives the conduction ratio output from the PI compensator 314 and the conduction ratio output from the PI compensator 318. The subtraction unit 310 calculates the difference obtained by subtracting the conduction ratio output from the PI compensator 318 from the conduction ratio output from the PI compensator 314, and outputs the difference to the gate signal generation unit 41.

[0064] The gate signal generating unit 41 includes comparison units 411 and 412 and negation units 413 and 414 . The comparator 411 receives the value of the conduction ratio supplied from the adder 319 of the duty calculation unit 31 and the triangular wave carrier of the upper circuit. The comparator 411 performs, for example, PWM control, compares the value of the conduction ratio with the value of the triangular wave carrier, and generates and outputs a gate signal for the semiconductor switching element S1.

[0065] The gate signal of semiconductor switching element S1 output from comparison unit 411 is input to NOT operation unit 413. NOT operation unit 413 generates and outputs a signal that is the inverse of the input value. The output signal of NOT operation unit 413 is the gate signal of semiconductor switching element S2.

[0066] The comparator 412 receives the duty ratio value supplied from the subtractor 310 of the duty calculation unit 31 and the triangular wave carrier of the lower circuit. The triangular wave carrier of the lower circuit is a triangular wave that is 180° phase shifted from the triangular wave carrier of the upper circuit. The comparator 412 performs, for example, PWM control, compares the duty ratio value with the triangular wave carrier value, and generates and outputs a gate signal for the semiconductor switching element S4.

[0067] The gate signal of semiconductor switching element S4 output from comparison unit 412 is input to NOT operation unit 414. NOT operation unit 414 generates and outputs a signal that is the inverse of the input value. The output signal of NOT operation unit 414 is the gate signal of semiconductor switching element S3. The configurations of the duty calculation unit 32-3n and the gate signal generation unit 42-4n are the same as those of the duty calculation unit 31 and the gate signal generation unit 41 described above.

[0068] As described above, the power supply device of this embodiment is similar to the second embodiment in that it calculates the duty factor component of the normal mode current common to the upper and lower circuits based on the difference between the current reference value and the value of the normal mode current. However, the power supply device of this embodiment differs from the second embodiment in that it calculates the duty factor component of the common mode current based on the difference between the common mode current reference value and the value of the common mode current.

[0069] In the power supply device of this embodiment, the sum of the duty factor component calculated using the normal mode current and the duty factor component calculated using the common mode current is used as the duty factor of the upper circuit, and the duty factor of the upper circuit is compared with the carrier wave to generate gate signals for the semiconductor switching elements S1 and S2 of the upper circuit.

[0070] Furthermore, in the power supply device of this embodiment, the difference between the duty factor component calculated using the normal mode current and the duty factor component calculated using the common mode current is used as the duty factor of the lower circuit, and the duty factor of the lower circuit is compared with the carrier wave to generate gate signals for the semiconductor switching elements S3 and S4 of the lower circuit. With this configuration, it is possible to provide a difference in the conduction rate between the upper circuit and the lower circuit in accordance with the common mode current component.

[0071] FIG. 8 is a diagram for explaining an example of the operation of the power supply device according to the third embodiment. Here, in the power supply device of this embodiment, when controlling a multi-parallel chopper circuit having unit choppers A and B, the gate signals of the semiconductor switching elements S1 and S4 of the unit choppers A and B, and the current (i A ), the current (i B ), the normal mode current of unit choppers A and B (i A / 2+i B / 2) and common mode current (i A / 2-i B8 shows an example of the conduction ratio between the upper and lower circuits of unit chopper A and unit chopper B, the carrier wave between the upper and lower circuits, and the conduction ratio between the upper and lower circuits of unit chopper A and unit chopper B. Note that Fig. 8 shows an example in which the conduction ratio is changed at the peak of the carrier wave in the lower circuit (the trough of the carrier wave in the upper circuit).

[0072] For example, as shown in Figure 6, the value of the normal mode current changes before and after the carrier cycle in response to changes in the duty ratio. Meanwhile, although the common mode current also changes, its value returns to its original value within the half cycle of the carrier wave, remaining the same before and after the carrier cycle. When the upper and lower circuits of unit choppers A and B have the same duty ratio, the first period, in which the switching patterns of unit chopper A and unit chopper B are different, occurs twice in the half cycle of the carrier wave. The duration of the two first periods that occur in the first half cycle of the carrier wave shown in Figure 6 is both t1. The duration of the two first periods that occur in the latter half cycle of the carrier wave shown in Figure 6 is both t2. Because the first periods occurring in the half cycle have the same durations, t1 and t2, the common mode current that flows due to differences in the switching patterns between unit chopper A and unit chopper B is reset (the changes are cancelled out) during the half cycle of the carrier wave, returning to the amplitude before the change.

[0073] For the reasons mentioned above, if the upper and lower circuits of each unit chopper A and B are made the same in terms of duty ratio, it is not possible to intentionally adjust the common-mode current of unit choppers A and B. Even if the same duty ratio is given between the upper and lower circuits of unit choppers A and B, it is thought that an unintentional difference in the duration of each of the first periods that occur twice in a carrier half cycle can occur, due to, for example, variations in gate signal transmission delay time or jitter in each semiconductor switching element, or switching timing delays caused by individual differences in the gate drive circuits that drive each element in response to the gate signal, resulting in the generation of a common-mode current. Due to the factors mentioned above, once a common-mode current is generated, it cannot be intentionally controlled and so remains in the output current of the unit choppers, causing a current imbalance between the unit choppers.

[0074] In contrast, in the example shown in Fig. 8, the conduction rate of the upper circuit of the unit chopper (upper stage duty) and the conduction rate of the lower circuit (lower stage duty) are different in the second half of the carrier period. In this example, as in the example shown in Fig. 6, the first period in which the switching patterns are different between unit chopper A and unit chopper B occurs twice in a half period of the carrier wave. In the first half of the carrier period, as in the example shown in Fig. 6, the conduction rate is the same between the upper circuit and the lower circuit of the unit chopper, so the time width of the two first periods that occur in the half period is the same, t1. On the other hand, in the second half of the carrier period, the time widths of the two first periods that occur in the half period are different, t2 and t3, respectively. As a result, the common mode current changes without being reset in the second half of the carrier period.

[0075] In the power supply device of this embodiment, by providing a difference in the conduction rate between the upper and lower circuits of the unit choppers, it is possible to intentionally control the common mode current and eliminate current imbalance between the unit choppers.

[0076] That is, according to this embodiment, it is possible to obtain the same effects as those of the first and second embodiments described above, and it is possible to provide a power supply device in which unit choppers are connected in multiple parallel connections, in which the current sharing of the unit choppers is equalized.

[0077] Next, a power supply device according to a fourth embodiment will be described in detail with reference to the drawings. FIG. 9 is a diagram schematically illustrating an example of the configuration of a power supply device according to the fourth embodiment. The power supply device of this embodiment differs from the third embodiment described above in the configuration of the control circuit CTR.

[0078] The control circuit CTR includes a gate signal generation unit 41-4n, a current calculation unit 61-6n, a common mode current controller 71-7n, a normal mode current controller 81-8n, a subtractor 91-9n, an adder 101-10n, an average normal mode current calculation unit AVE1, and an average value current controller AVE2. Note that the gate signal generation unit 41-4n, current calculation unit 61-6n, common mode current controller 71-7n, normal mode current controller 81-8n, subtractor 91-9n, and adder 101-10n all have the same configuration, so the following description will focus on the gate signal generation unit 41, the current calculation unit 61, the common mode current controller 71, the normal mode current controller 81, the subtractor 91, and the adder 101, and redundant description will be omitted.

[0079] The current calculation unit 61 acquires the detection values ​​of the current sensors A11 and A12 and calculates the values ​​of the normal mode current and the common mode current. That is, the current calculation unit 61 has a configuration similar to that of the adder 311 and dividers 312, 315, and 316 in the power supply device of the third embodiment. The current calculation unit 61 supplies the calculated common mode current value to the common mode current controller 71. The current calculation unit 61 supplies the calculated normal mode current value to the normal mode current controller 81 and the normal mode current average value calculation unit AVE1.

[0080] The common mode current controller 71 receives the common mode current value supplied from the current calculation unit 61 and a common mode current command value. The common mode current controller 71 outputs a component (second component) of the duty ratio calculated so that the difference obtained by subtracting the common mode current value from the common mode current command value becomes zero. That is, the common mode current controller 71 has the same configuration as the subtraction unit 317 and PI compensator 318 in the power supply device of the third embodiment.

[0081] Normal mode current average value calculation unit AVE1 acquires the normal mode current values ​​calculated by current calculation units 61-6n, and calculates the average of the acquired current values ​​(normal mode current average value). Normal mode current average value calculation unit AVE1 supplies the calculated normal mode current average value to normal mode current controllers 81-8n and average value current controller AVE2.

[0082] Normal mode current controller 81 sets the normal mode current average value as a first current reference value, and outputs a component (first component) of the duty ratio calculated so that the difference between the normal mode current value supplied from current calculator 61 and the first current reference value is zero. That is, normal mode current controller 81 has configurations similar to those of subtractor 313 and PI compensator 314 in the power supply device of the third embodiment.

[0083] Average current controller AVE2 calculates a component of the duty ratio (normal mode average duty ratio) so that the difference between the normal mode current average value and the second current reference value becomes zero. Average current controller AVE2 supplies the calculated normal mode average duty ratio to adders 101-10n.

[0084] The subtractor 91 calculates the difference obtained by subtracting the component of the duty ratio output from the common mode current controller 71 from the component of the duty ratio output from the normal mode current controller 81 , and outputs the difference to the adder 101 . The adder 101 adds the duty ratio component output from the subtractor 91 and the normal mode average duty ratio output from the average value current controller AVE2 to calculate the duty ratio of the unit chopper 21, and supplies it to the gate signal generator 41.

[0085] As described above, in the power supply device of this embodiment, a common duty ratio is used between the upper and lower circuits for the plurality of unit choppers 21-2n, calculated from duty ratio components calculated from the normal mode average current value and the normal mode current value of each of the plurality of unit choppers 21-2n, duty ratio components calculated from the common mode current value and common mode current command value of each of the plurality of unit choppers 21-2n, and the normal mode average duty ratio. That is, in the power supply device of this embodiment, a normal mode average duty ratio is calculated for using the average of the normal mode current values ​​of the plurality of unit choppers 21-2n as the current reference value, and a gate signal for each of the plurality of unit choppers 21-2n is generated based on the duty ratio obtained by adding this normal mode average duty ratio. This makes it possible to make the normal mode current values ​​of the plurality of unit choppers 21-2n follow the average value, and to make the average normal mode current value follow the second current reference value.

[0086] That is, according to this embodiment, it is possible to obtain the same effect as the first embodiment described above, and to provide a power supply device in which unit choppers are connected in multiple parallel connections, in which the current sharing of the unit choppers is equalized.

[0087] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0088] 10... DC power supply, 21-2n... unit chopper, 31-3n... duty calculation unit, 41-4n... gate signal generation unit, 50... load, 61-6n... current calculation unit, 71-7n... common mode current controller, 81-8n... normal mode current controller, 91-9n... subtractor, 101-10n... adder, 201-20n... chopper control circuit, 310, 313, 315, 317... Subtraction units, 311, 319...addition units, 312, 316...division units, 314, 318...PI compensators, 411, 412...comparison units, 413, 414...negation operation units, A11-An1...current sensors, AVE1...normal mode current average value operation unit, AVE2...average value current controller, C1, C2...capacitors, L11-Ln1...reactors, S1-S4...semiconductor switching elements

Claims

1. a multi-parallel chopper circuit including a plurality of unit choppers each including an upper stage circuit and a lower stage circuit connected in series between a positive electrode and a negative electrode, a first capacitor connected in parallel with the upper stage circuit, a second capacitor connected in parallel with the lower stage circuit, a first reactor connected to an output terminal of the upper stage circuit, and a second reactor connected to an output terminal of the lower stage circuit, each of the upper stage circuit and the lower stage circuit having at least one switching element, electrically connecting the positive electrode and the negative electrode of each of the plurality of unit choppers to each other, and electrically connecting the output terminal of the upper stage circuit to the output terminal of the lower stage circuit, a duty calculation unit that calculates a conduction ratio of the unit chopper by using an output current value of the upper circuit and an output current value of the lower circuit; a signal generating unit that generates a signal for controlling operation of the switching elements of the upper circuit and the lower circuit using the conduction ratio.

2. 2. The power supply device according to claim 1, wherein the plurality of unit choppers are electrically connected to each other at an interconnection point between the first capacitor and the second capacitor.

3. 2. The power supply device according to claim 1, wherein the duty calculation section calculates the conduction ratio so that an average value of the output current value of the upper circuit and the output current value of the lower circuit tracks a current reference value.

4. the signal generating unit generates a signal for controlling the switching element of the upper stage circuit by comparing the conduction rate with a carrier wave of the upper stage circuit, and generates a signal for controlling the switching element of the lower stage circuit by comparing the conduction rate with a carrier wave of the lower stage circuit; 2. The power supply device according to claim 1, wherein the carrier wave of said upper circuit and the carrier wave of said lower circuit are out of phase with each other by 180 degrees.

5. 2. The power supply device according to claim 1, wherein the duty calculation unit calculates the conduction rate for the upper circuit and the conduction rate for the lower circuit, respectively, using an average value of the output current value of the upper circuit and the output current value of the lower circuit, and a value obtained by subtracting the output current value of the lower circuit from the output current value of the upper circuit and dividing the difference by two.

6. a normal mode current average value calculation unit that calculates a normal mode current average value by averaging the average values ​​of the output current values ​​of the upper stage circuits and the output current values ​​of the lower stage circuits of the plurality of unit choppers; an average current controller that calculates a normal mode average duty factor so that the normal mode current average value follows a second current reference; 2. The power supply device according to claim 1, wherein the duty calculation unit calculates, for each of the plurality of unit choppers, as the duty ratio, a value obtained by adding the normal mode average duty ratio to a difference between a first component of the duty ratio calculated so that the average value follows the normal mode current average value and a second component of the duty ratio calculated so that a common mode current value, which is a value obtained by dividing a difference obtained by subtracting the output current value of the lower circuit from the output current value of the upper circuit, and dividing the difference by two, as the duty ratio.

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