JP2015027177A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new DC/DC power conversion device that reduces a primary circuit loss or cost by making a primary circuit common to a plurality of transformers, and suppresses a current value imbalance between secondary circuits disposed for the respective transformers to the utmost.SOLUTION: A total output quantity amounting to the sum of output currents or output voltages (both collectively referred to as output quantities) of the secondary circuits disposed for the plurality of respective transformers is divided by the number of transformers to produce a balanced output quantity, the balanced output quantity is then compared with the output quantity of each secondary circuit, and switching elements of each secondary circuit are controlled such that the output quantity of each secondary circuit converges to the balanced output quantity. Since the primary circuit is made common to the plurality of transformers, a primary circuit loss or cost can be reduced, and since the output quantities of the secondary circuits of the respective transformers can be made close to each other to the utmost, a current value imbalance between the secondary circuits disposed for the respective transformers can be suppressed.

Description

  The present invention relates to a power converter for boosting or stepping down a DC voltage, and more particularly to an insulated power converter using a transformer.

  A power converter that boosts or steps down a DC voltage (hereinafter referred to as a DC / DC power converter) is a power converter that provides a DC voltage suitable for each load by boosting or stepping down the DC voltage.

  This DC / DC power conversion device is used in, for example, a hybrid vehicle or an electric vehicle, and since it is difficult to generate power with an alternator in the hybrid vehicle or the electric vehicle, the voltage is stepped down from a high voltage battery to an auxiliary device having a low operating voltage. A necessary type of power is supplied by using a DC / DC power converter of a type. In this case, since the voltage of the high voltage battery is high, in consideration of safety, the DC / DC power converter uses an insulated DC / DC power converter using a transformer.

  In an insulated DC / DC power converter using a transformer, when a direct current voltage is stepped down, a large current flows through a secondary circuit on the low voltage side. Therefore, there is a problem that loss increases due to element resistance and wiring resistance in the secondary circuit. In addition, since the DC / DC power converter performs rough voltage conversion by a transformer, the number of turns of the primary winding and the secondary winding wound around the transformer is mainly determined by the applied voltage. Therefore, the higher the applied voltage, the greater the number of turns required. As the number of turns of the transformer increases, the loss due to the resistance of the transformer winding increases. Moreover, the volume of the insulation area | region required for insulation between windings increases, and the subject that the external shape of a transformer becomes large occurs.

  In order to meet such a problem, the parallelization of DC / DC power converters has been studied. Such a paralleled DC / DC power converter is described in, for example, Japanese Patent Laid-Open No. 2005-224669 (Patent Document 1).

  Then, the parallel current of the DC / DC power converters distributes the current flowing through each circuit that performs power conversion. Since the loss caused by the resistance is the product of the resistance of the element or wiring and the square of the current flowing through the element or wiring, the loss in the element or wiring is reduced by parallelizing the DC / DC power converter. Become. Furthermore, by paralleling DC / DC power converters, voltage or current is distributed using multiple transformers, resulting in high efficiency and reduced size due to loss reduction in transformer windings due to the reduction in the number of transformer turns. Can be realized.

JP 2005-224669 A

  By the way, in Patent Document 1, a power conversion circuit having six capacitors, six switching elements, three transformers, and six rectifying elements connected in series is connected to an input terminal of a switching power supply. The voltage generated by the above-described power conversion circuit is output to the common output terminal.

  In the DC / DC power converter configured as described above, the primary circuit is connected in series, so that the voltage applied to each transformer is reduced. As a result, the loss in the transformer winding can be reduced and the size can be reduced. Further, the parallel current of the DC / DC power converters distributes the current flowing through each circuit. As described above, the loss on the circuit is a multiplication of the resistance of the element or wiring and the square of the current flowing through the element or wiring, and therefore the loss is reduced by parallelization of the DC / DC power converters.

  However, since the loss in the diode which is a rectifying element is a product of the forward voltage of the diode and the current flowing through the diode, the loss per diode is reduced by distributing the current. The total loss does not decrease significantly. Therefore, in the DC / DC power converter of Patent Document 1, the forward voltage of the diode of the secondary circuit is normally about 1V, and since six diodes are used, it is difficult to achieve high efficiency. is there. In Patent Document 1, since three transformers are used, twice the number of capacitors, switching elements, and rectifying elements are necessary, but at least two transformers are required for parallelization. In order to use, twice the number of capacitors, switching elements, and rectifying elements are required. In any case, there is a problem that it is difficult to increase the efficiency.

  Therefore, it can be considered to use a synchronous rectifier circuit using a semiconductor element such as a MOSFET instead of the diode. In the case of the synchronous rectifier circuit, the ON resistance loss in the semiconductor element is a product of the ON resistance of the semiconductor element and the square of the current flowing through the semiconductor element. Since the loss of the semiconductor element alone is reduced by the square of the current, the total loss of the semiconductor elements of the secondary circuit can be reduced.

  However, when the synchronous rectifier circuit is employed in the secondary circuit as described above, there are the following problems. In other words, due to variations in the wiring and semiconductor elements of the half-bridge circuit that constitutes the secondary circuit for each transformer, and changes in the characteristics of the semiconductor element due to temperature, there is an imbalance in the current value between the secondary circuits that share each transformer. Is to occur.

  In addition, in order to control the output current according to the ON / OFF duty ratio of the switching element of each primary circuit, when paralleling the DC / DC power converter, each switching element of each primary circuit of each parallel circuit It is possible to control the amount of current. However, a high voltage element is used as a switching element for connecting the primary circuit to the high voltage battery. Generally, a high breakdown voltage element has a high ON resistance, which causes an increase in loss, and a high breakdown voltage element has an attribute of higher cost than a low breakdown voltage element. For this reason, it is conceivable to reduce the number of switching elements in the primary circuit by sharing the primary circuit, thereby reducing loss or cost.

  However, sharing the primary circuit is advantageous in terms of loss and cost, but since the primary circuit is not provided for each transformer, the amount of current cannot be controlled by the switching element of the primary circuit. Furthermore, since the currents of the secondary circuits cannot be controlled as described above, there is a problem that current value imbalance occurs between the secondary circuits of each transformer.

  An object of the present invention is to reduce the primary circuit loss or cost by making the primary circuit common to a plurality of transformers, and to allow the current values of the secondary circuits provided for each transformer to be unbalanced. It is an object of the present invention to provide a novel DC / DC power converter that can be suppressed as much as possible.

  The feature of the present invention is that the actual output current of the secondary circuit provided for each of a plurality of transformers or the total output amount obtained by adding the output voltages (both are collectively referred to as the output amount) is divided by the number of transformers to obtain an equal output amount. Compare the equal output amount with the actual output amount of each secondary circuit, and control the switching element of each secondary circuit so that the output amount of each secondary circuit converges to the equal output amount. is there.

  According to the present invention, since the primary circuit is shared by a plurality of transformers, the loss or cost of the primary circuit can be reduced, and the output amount of the secondary circuit for each transformer can be made as close as possible to each other. Therefore, it is possible to suppress the imbalance between the output amounts of the secondary circuits provided for each transformer.

It is a circuit diagram which shows the circuit structure of the DC / DC power converter device which becomes the 1st Embodiment of this invention. It is a wave form diagram explaining the waveform of the main site | parts of the DC / DC power converter device shown in FIG. It is explanatory drawing explaining the phase waveform of the gate signal of the switching element of the secondary circuit of the DC / DC power converter device shown in FIG. It is explanatory drawing explaining the duty waveform of the gate signal of the switching element of the secondary circuit of the DC / DC power converter device shown in FIG. It is a circuit diagram which shows the circuit structure of the DC / DC power converter device which becomes the 2nd Embodiment of this invention. It is a circuit diagram which shows the circuit structure of the DC / DC power converter device which becomes the 3rd Embodiment of this invention. It is a circuit diagram which shows the circuit structure of the DC / DC power converter device which becomes the 4th Embodiment of this invention. It is a wave form diagram explaining the waveform of the main site | parts of the DC / DC power converter device shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples are included in the technical concept of the present invention. Is also included in the range.

  Next, the configuration of the DC / DC power converter according to the first embodiment of the present invention will be described in detail with reference to FIG. In this embodiment, a DC / DC power conversion device is used in which the primary circuit is configured in a half-bridge type, and the primary windings are shared by connecting the primary windings of a plurality of transformers in series.

  The half-bridge type DC / DC power conversion device 1 according to the present embodiment includes a plurality of transformers, here, a first transformer 31 and a second transformer 32, and primary windings 31a of the transformers 31 and 32, One end of 32a is connected. The other end of the primary winding 31a of the first transformer 31 is connected to one end of the resonance coil 42, and the other end of the resonance coil 42 is connected between the lower end of the switching element 27 and the upper end of the switching element 28. The other end of the primary winding 32 a of the transformer 32 is connected between the lower end of the capacitor 23 and the upper end of the capacitor 24.

  The upper end of the switching element 27 and the upper end of the capacitor 23 are connected to the input terminal 22 a, and the input terminal 22 a is connected to the positive electrode of the DC power supply 21. The lower end of the switching element 28 and the lower end of the capacitor 24 are connected to the input terminal 22 b, and the input terminal 22 b is connected to the negative electrode of the DC power supply 21. In this way, the primary circuit is configured as a half-bridge circuit, and the primary circuit is shared by the first transformer 31 and the second transformer 32. As a result, since no primary circuit is provided for each transformer, power loss of the primary circuit can be reduced and the cost of the primary circuit can be reduced.

  Further, in the first half bridge circuit 200 constituting the secondary circuit corresponding to the first transformer 31, the upper end of the switching element 201 and the upper end of the capacitor 203 are connected, and the lower end of the switching element 202 and the lower end of the capacitor 204 are connected. Is connected to the lower end of the smoothing capacitor 36. Further, one end of the secondary winding 31 b of the first transformer 31 is between the lower end of the capacitor 203 and the upper end of the capacitor 204 of the first half-bridge circuit 200, or between the lower end of the switching element 201 and the upper end of the switching element 202. It is connected to the. Similarly, the other end of the secondary winding 31b of the first transformer 31 is connected between the lower end of the switching element 201 and the upper end of the switching element 202, or between the lower end of the capacitor 203 and the upper end of the capacitor 204. . Further, one end of the choke coil 35 is connected from each connection point, and the other end of the choke coil 35 is connected to the positive electrode of the smoothing capacitor 36.

  Further, in the second half bridge circuit 210 constituting the secondary circuit corresponding to the second transformer 32, the upper end of the switching element 211 and the upper end of the capacitor 213 are connected, and the lower end of the switching element 212 and the capacitor 214 are connected. The lower end is connected to the lower end of the smoothing capacitor 36. One end of the secondary winding 32b of the second transformer 32 is connected between the lower end of the capacitor 213 and the upper end of the capacitor 214 of the second half-bridge circuit 210 or between the lower end of the switching element 211 and the upper end of the switching element 212. Has been. Similarly, the other end of the secondary winding 32b of the second transformer 32 is between the lower end of the switching element 211 and the upper end of the switching element 212 of the second half bridge circuit 210, or the lower end of the capacitor 213 and the capacitor 214. Connected between top ends. Further, one end of the choke coil 39 is connected from each connection point, and the other end of the choke coil 39 is connected to the positive electrode of the smoothing capacitor 36.

  The first half-bridge circuit 200 and the second half-bridge circuit 210 are combined at the output terminals 40a and 40b to be the final output. The load 41 is connected in parallel with the smoothing capacitor 36, and these are connected to the output terminals 40a and 40b, respectively. Further, the windings 31a, 31b, 32a, 32b of the first transformer 31 and the second transformer 32 are connected so that the polarities of the primary circuit and the secondary circuit are equal.

  Here, the first transformer 31 and the second transformer 32 have the same specifications, and the number of turns and the turn ratio are set equal. In addition, since the number of turns is equal, the excitation inductance is also equal. The above is the circuit configuration when the DC / DC power converters are parallelized.

  Next, the structure for suppressing the imbalance of the output current of the secondary circuit, which is a characteristic part of the present invention, will be described. In this embodiment, the half bridge circuits 200 and 210 constituting the respective secondary circuits are MOSFETs. Synchronous rectification circuits using semiconductor elements such as these are used. The present embodiment is characterized in that an output adjustment unit for adjusting the output of the secondary circuit using this synchronous rectifier circuit is provided.

  Below, the structure which suppresses the imbalance of the output current of a secondary circuit is demonstrated. Here, the secondary circuit basically includes secondary coils 31b and 32b for each transformer, half-bridge circuits 200 and 210 for each transformer, and choke coils 35 and 39 for each transformer.

  In FIG. 1, the output currents or output voltages (hereinafter collectively referred to as output amounts) of the first half-bridge circuit 200 and the second half-bridge circuit 210 are the first half-bridge circuit 200. And the second half-bridge circuit 210 and the output terminal 40b. In this embodiment, a current value is detected, and this current value is hereinafter referred to as an output amount. The respective output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are added by an adder 43 having an adding function, and the total output amount is obtained.

  The total output amount obtained by the adder 43 is sent to the apportioning controller 44 having an apportioning function, and is divided by the number of transformers 31 and 32 to obtain an equal output amount. In this embodiment, since there are two transformers, the equal output amount is ½ of the total output amount. Therefore, if the output of each secondary circuit is controlled to this equal output amount, it becomes possible to suppress the imbalance between the current values of the secondary circuits provided for each transformer.

  Further, the apportioning controller 44 is configured such that the output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are individually input in parallel. Accordingly, the proportional distribution controller 44 outputs the equal output amount divided by the number of the transformers 31 and 32 and the respective output amounts of the first half bridge circuit 200 and the second half bridge circuit 210 as described above. It will be.

  The equal output amount output from the apportioning controller 44 and the output amounts of the half-bridge circuits 200 and 210 are input to the first comparator 45 and the second comparator 46 having a comparison function. . An equal output amount is input to the first comparator 45 and the second comparator 46 in common, but the output amount of the first half-bridge circuit 200 is input to the first comparator 45, and The output of the second half bridge circuit 210 is input to the second comparator 45. Accordingly, in each of the comparators 45 and 46, if the output amount is larger than the equal output amount, a comparison output signal for reducing the output amount is output, and if the output amount is smaller than the equal output amount, the output amount is set. A comparison output signal for enlarging is output. A differential amplifier having the same function as the comparators 45 and 46 may be used.

  The comparison output signal of the first comparator 45 is input to the first switching element controller 47 having a function of adjusting the gate signals of the switching elements 201 and 202 of the first half bridge circuit 200. Similarly, the comparison output signal of the second comparator 46 is input to the second switching element controller 48 that adjusts the gate signals of the switching elements 211 and 212 of the second half bridge circuit 210. These switching element controllers 47 and 48 adjust the energization phase timing when each switching element 201, 202, 211, and 212 is switched ON and the energization phase amount that is the energization time to adjust each half. The output amounts of the bridge circuits 200 and 210 can be controlled, and the switching element controllers 47 and 48 function as output variable function units.

  Thus, the adder 43, the apportionment controller 44, the comparators 45 and 46, and the switching element controllers 47 and 48 form a feedback system, and these function units constitute an output adjustment unit. .

  For example, the output amount can be adjusted by changing the energization phase amount of the switching elements 201, 202, 211, 212 of the half bridge circuits 200, 210 with respect to the switching elements 27, 28 of the primary circuit. Further, the output amount can be adjusted by changing the energization phase timing by giving a phase difference to the gate signals of the switching elements of the half bridge circuits 200 and 210 with respect to the gate signals of the switching elements 27 and 28 of the primary circuit. In the present embodiment, what is essential is that the output of the secondary circuit can be adjusted, and its specific configuration and method are not limited.

  In this way, a feedback system is formed by the half-bridge circuits 200 and 210, the adder 43, the proportional distribution controller 44, the comparators 45 and 46, and the switching element controllers 47 and 48. Accordingly, the outputs of the respective half-bridge circuits 200 and 210 are controlled so as to converge to the equal output amount obtained by the apportionment controller 44, and the mutual current values of the secondary circuits provided for each transformer. It becomes possible to suppress this imbalance.

  Next, the operation of the DC / DC power converter shown in FIG. 1 will be described with reference to FIG. Since the operation is a cycle determined by the carrier frequency, one cycle will be described. Here, FIG. 2 is a waveform diagram showing signal waveforms of main parts of the DC / DC power converter.

  2, (a) and (b) of FIG. 2 show driving waveforms of the first switching element 27 and the second switching element 28 of the primary circuit, and (c) and (d) are the first half bridges. The drive waveforms of the first switching element 201 and the second switching element 202 of the circuit 200 are shown, and (e) and (f) are the first switching element 211 and the second switching element 212 of the second half-bridge circuit 210, respectively. A drive waveform is shown, (g) has shown the current waveform of the 1st transformer and the 2nd transformer.

  First, the operation of the first winding 31a of the first transformer 31 and the current flowing through the primary winding 32a of the second transformer 32 during the time T0 to T1 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, the first switching element 27 is turned on, the second switching element 28 is turned off, and the voltage charged in the second capacitor 23 is The voltage is applied to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32.

  As shown in FIGS. 2C and 2D, in the first half-bridge circuit 200, the first switching element 201 of the first half-bridge circuit 200 is in an OFF state, and the second switching element 202 is It is on. At this time, the electric charge is discharged from the second capacitor 204 of the first half-bridge circuit 200, the current flowing through the secondary winding 31b of the first transformer 31 increases, and the primary winding 31a of the first transformer 31. The current that flows through increases.

  Further, as shown in FIGS. 2E and 2F, in the second half-bridge circuit 210 as well, the first switching element 211 is in the OFF state and the second switching element 212 is in the ON state. The electric charge is discharged from the second capacitor 214 of the second half-bridge circuit 210, the current flowing through the secondary winding 32b of the second transformer 32 increases, and the primary winding 32a of the second transformer 32 increases. The flowing current increases. Further, as the times T0 to T1 approach the 1/2 cycle, the amount of current increase increases and the output current increases.

  Next, the operation at time T1 to T2 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, the first switching element 27 is in the on state, the second switching element 28 is in the off state, and the voltage charged in the first capacitor 23 is the first voltage. Applied to the primary winding 31a of the transformer 31 and the primary winding 32a of the second transformer 32. As shown in FIGS. 2C and 2D, in the first half-bridge circuit 200, the first switching element 201 of the first half-bridge circuit 200 is in an OFF state, and the second switching element 202 is The first capacitor 203 of the first half-bridge circuit 200 starts to be charged, the electric charge is continuously discharged from the second capacitor 204, and the secondary winding 31b of the first transformer 31 is charged. The flowing current is constant, and the current flowing through the primary winding 31a of the first transformer 31 is constant.

  Further, as shown in FIGS. 2E and 2F, in the second half-bridge circuit 210, the first switching element 211 and the second switching element 212 of the second half-bridge circuit 210 are turned off. Thus, charging of the first capacitor 213 of the second half-bridge circuit 210 starts to be charged, the charge continues to be discharged from the second capacitor 214, and the current flowing through the secondary winding 32b of the second transformer 32 becomes The current flowing in the primary winding 32a of the second transformer 32 is constant.

  Next, operations at times T2 to T3 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, the first switching element 27 is in the on state, the second switching element 28 is also in the off state, and the voltage charged in the first capacitor 23 is The voltage is applied to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32. Further, as shown in FIGS. 2C and 2D, in the first half-bridge circuit 200, the first switching element 201 is turned on, the second switching element 202 is turned off, The first capacitor 203 of one half-bridge circuit 200 continues to be charged, the second capacitor 204 continues to discharge charge, the current flowing through the secondary winding 31b of the first transformer 31 becomes constant, and the first The current flowing through the primary winding 31a of one transformer 31 is constant.

  As shown in FIGS. 2E and 2F, in the second half-bridge circuit 210, the first switching element 211 of the second half-bridge circuit 210 is turned on, and the second switching element 212 is in an off state, the first capacitor 213 of the second half-bridge circuit 210 continues to be charged, the second capacitor 214 continues to be discharged, and the secondary winding 32b of the second transformer 32 The current flowing in the first transformer 32 becomes constant, and the current flowing in the primary winding 32a of the second transformer 32 becomes constant.

  Next, the operation at times T3 to T4 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, the first switching element 27 is turned off, the second switching element 28 is turned off, and the primary winding 31a of the first transformer 31 No voltage is applied to the primary winding 32a of the second transformer 32. Further, as shown in FIGS. 2C and 2D, in the first half-bridge circuit 200, the first switching element 201 of the first half-bridge circuit 200 is in the on state, and the second switching element 202 is in an off state, the first capacitor 203 of the first half-bridge circuit 200 continues to be charged, the second capacitor 204 continues to discharge, and the secondary winding 31b of the first transformer 31 The current flowing in the first transformer 31 becomes constant, and the current flowing in the primary winding 31a of the first transformer 31 becomes constant.

  As shown in FIGS. 2E and 2F, in the second half-bridge circuit 210, the first switching element 211 of the second half-bridge circuit 210 is turned on, and the second switching element 212 is in an off state, the first capacitor 213 of the second half-bridge circuit 210 continues to be charged, the second capacitor 214 continues to be discharged, and the secondary winding 32b of the second transformer 32 The current flowing in the first transformer 32 becomes constant, and the current flowing in the primary winding 32a of the second transformer 32 becomes constant.

  Next, the operation at times T4 to T5 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, the first switching element 27 is in the off state, the second switching element 28 is in the on state, and the voltage charged in the second capacitor 24 is A voltage is applied to the primary winding 31a of the first transformer 31 and the primary winding 32a of the second transformer 32 in the opposite directions.

  Further, as shown in FIGS. 2C and 2D, in the first half-bridge circuit 200, the first switching element 201 of the first half-bridge circuit 200 is in the on state, and the second switching element 202 is turned off, and the first capacitor 203 of the first half-bridge circuit 200 starts to discharge electric charges. The second capacitor 204 continues to discharge electric charges, and the secondary winding 31b of the first transformer 31 is discharged. The current flowing through the first transformer 31 starts to decrease, and the current flowing through the primary winding 31a of the first transformer 31 decreases.

  Further, as shown in FIGS. 2E and 2F, in the second half-bridge circuit 210, the first switching element 211 of the second half-bridge circuit 210 is in an ON state, and the second switching element 212 is turned on. Is turned off, the first capacitor 213 of the second half-bridge circuit 210 starts discharging electric charge, continues to discharge electric charge from the second capacitor 214, and the secondary winding 32b of the second transformer 32 The flowing current starts to decrease, and the current flowing through the primary winding 32a of the second transformer 32 decreases. As the times T4 to T5 approach the 1/2 cycle, the amount of increase in current decreases and the output current decreases.

  Next, the operation at times T5 to T6 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, the first switching element 27 is in the off state, the second switching element 28 is in the on state, and the voltage charged in the second capacitor 24 is the first voltage. Applied to the primary winding 31a of the transformer 31 and the primary winding 32a of the second transformer 32 in opposite directions. Further, as shown in FIGS. 2C and 2D, in the first half-bridge secondary circuit, the first switching element 201 of the first half-bridge circuit 200 is turned off, and the second switching is performed. The element 202 is in an off state, the discharge of the electric charge is finished in the first capacitor 203 of the first half-bridge circuit 200, the electric charge is discharged in the second capacitor 204, and the secondary of the first transformer 31 The current flowing through the winding 31b is constant, and the current flowing through the primary winding 31a of the first transformer 31 is constant.

  As shown in FIGS. 2E and 2F, in the second half-bridge circuit 210, the first switching element 211 of the second half-bridge circuit 210 is turned off, and the second switching element 212 is in the OFF state, the discharge of the electric charge is completed by the first capacitor 213 of the second half-bridge circuit 210, the electric charge is discharged by the second capacitor 214, and the secondary winding of the second transformer 32 is completed. The current flowing through the line 32b is constant, and the current flowing through the primary winding 32a of the second transformer 32 is constant.

  Next, the operation at times T6 to T7 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, when the first switching element 27 is in the OFF state and the second switching element 28 is in the ON state, the voltage charged in the first capacitor 24 is the first voltage. The reverse voltage is applied to the primary winding 31 a of the transformer 31 and the primary winding 32 a of the second transformer 32. Further, as shown in FIGS. 2C and 2D, in the first half-bridge circuit 200, the first switching element 201 of the first half-bridge circuit 200 is in the OFF state, and the second switching element 202 is turned on, current does not flow through the first capacitor 203 of the first half-bridge circuit 200, charging of the electric charge is started by the second capacitor 204, and the secondary winding 31 b of the first transformer 31. The current flowing in the first transformer 31 becomes constant, and the current flowing in the primary winding 31a of the first transformer 31 becomes constant.

  As shown in FIGS. 2E and 2F, in the second half-bridge circuit 210, the first switching element 211 of the second half-bridge circuit 210 is turned off, and the second switching element 212 is turned on, no current flows through the first capacitor 213 of the second half-bridge circuit 210, charging at the second capacitor 214 is started, and the secondary winding 32 b of the second transformer 32 is applied to the secondary winding 32 b. The flowing current is constant, and the current flowing through the primary winding 32a of the second transformer 32 is constant.

  Next, the operation at times T7 to T8 in FIG. 2 will be described. As shown in FIGS. 2A and 2B, the first switching element 27 is turned off, the second switching element 28 is turned off, and the primary winding 31a of the first transformer 31 and the second winding No voltage is applied to the primary winding 32a of the transformer 32. Further, as shown in FIGS. 2C and 2D, in the first half-bridge circuit 200, the first switching element 201 of the first half-bridge circuit 200 is in an OFF state, and the second switching element 202 is turned off. Is in the ON state, no current flows through the first capacitor 203 of the first half-bridge circuit 200, the electric charge continues to be charged by the second capacitor 204, and the current flows through the secondary winding 31b of the first transformer 31. Becomes constant, and the current flowing through the primary winding 31a of the first transformer 31 becomes constant.

  Further, as shown in FIGS. 2E and 2F, in the second half-bridge circuit 210, the first switching element 211 of the second half-bridge circuit 210 is in the OFF state, and the second switching element 212 is turned off. Is in the ON state, no current flows through the first capacitor 213 of the second half-bridge circuit 210, and the charge continues to be charged from the second capacitor 214, and the secondary winding 32b of the second transformer 32 is charged. The flowing current is constant, and the current flowing through the primary winding 32a of the second transformer 32 is constant.

  The output amount can be adjusted by controlling the gate signals of the switching elements 201, 202, 211 and 212 of the half bridge circuits 200 and 210 for the switching elements 27 and 28 of the primary circuit. As described above, the half bridge circuits 200 and 210, the adder 43, the proportional distribution controller 44, the comparators 45 and 46, and the switching element controllers 47 and 48 form a feedback system. Accordingly, the outputs of the half-bridge circuits 200 and 210 are controlled by the switching element controllers 47 and 48 so as to converge to the equal output amount obtained by the apportionment controller 44, and provided for each transformer. It becomes possible to suppress the imbalance between the current values of the secondary circuits.

  For example, the switching element controllers 47 and 48 control the ON timing of the gate signals of the switching elements 201, 202, 211, and 212 of the half bridge circuits 200 and 210, that is, the energization phase timing for switching, thereby controlling each half bridge circuit. The charging / discharging time of the capacitors 203, 204, 213, and 214 in the next circuit changes. By controlling the charge / discharge time, the output amount of each half-bridge circuit 200 and 210 can be controlled. Of course, the output amount can be adjusted by changing the energization phase amount of the switching elements 201, 202, 211, 212 of the half-bridge circuits 200, 210.

  FIG. 3 shows a case where the energization phase timing which is the ON timing of the gate signals of the switching elements 201, 202, 211 and 212 is controlled. As shown in FIG. 3, the gate signal having a phase difference of φ1 and φ2 is given to the gate signals of the high-side switching elements 201 and 211 of the half-bridge circuits 200 and 210 with respect to the gate signal of the primary circuit. Yes. In this case, the energization phase timing of the first switching element 211 of the second half-bridge circuit 210 is delayed with respect to the energization phase timing of the first switching element 201 of the first half-bridge circuit 200. It has come to be. The energization phase amounts of the first switching elements 201 and 202 are set to the same time. Here, the low-side switching elements 202 and 212 may be operated complementarily to the high-side switching elements 201 and 211 with a dead time. Further, as is well known, the time ratio between the first switching element 27 and the second switching element 28 which are switching elements of the primary circuit, the first switching element 201 and the second switching element 202 of the first half-bridge circuit 200. The time ratio and the time ratio of the first switching element 211 and the second switching element 212 of the second half-bridge circuit 210 are alternately turned ON / OFF so that the total time ratio thereof becomes 1.

  In this way, the amount of deviation of the actual output amount of the secondary circuit from the equal output amount of each secondary circuit provided in each transformer obtained by the proportional distribution controller 44 is compared. 45 and 46, and based on the comparison result, the phase difference between φ1 and φ2 is applied to the gate signals of the high-side switching elements 201 and 211 of the half bridge circuits 200 and 210 by the switching element controllers 47 and 48, respectively. It is set as the structure which gives the gate signal which has. As a result, the outputs of the respective half-bridge circuits 200 and 210 are controlled, and the secondary corresponding to each transformer due to variations in the elements and wiring of the respective half-bridge circuits 200 and 210 and changes in element characteristics due to temperature. This makes it possible to correct the output amount imbalance among the circuits.

  Next, FIG. 4 shows a case where the energization phase amount which is the time during which the gate signals of the switching elements 201, 202, 211 and 212 are ON is controlled. FIG. 4 shows a so-called so-called output amount of the secondary circuit by controlling the ON time (ON duty) of the gate signals of the switching elements 201 and 211 on the high side of the half-bridge circuits 200 and 210. It is the structure which controls. In this case as well, the comparator shows how much the actual output amount of the secondary circuit is deviated from the equal output amount of each secondary circuit provided in each transformer obtained by the apportioning controller 44. 45 and 46, and based on the comparison result, the switching element controllers 47 and 48 give the gate signals corresponding to the energization phase amount to the switching elements 201 and 211 on the high side of the half bridge circuits 200 and 210, respectively. It is configured. As a result, the outputs of the respective half-bridge circuits 200 and 210 are controlled, and the secondary corresponding to each transformer due to variations in the elements and wiring of the respective half-bridge circuits 200 and 210 and changes in element characteristics due to temperature. This makes it possible to correct the output amount imbalance among the circuits.

  As shown in FIG. 4, the output amount (current value) of the choke coil 35 is controlled corresponding to the energization phase amount applied to the switching element 201 of the first half bridge circuit 200, and the switching of the second half bridge circuit 210 is performed. The output amount (current value) of the choke coil 39 is controlled in accordance with the energization phase amount applied to the element 211. As a result, the outputs of the respective half-bridge circuits 200 and 210 are controlled, and the secondary corresponding to each transformer due to variations in the elements and wiring of the respective half-bridge circuits 200 and 210 and changes in element characteristics due to temperature. This makes it possible to correct the output amount imbalance among the circuits.

  In addition, in this embodiment, the voltage applied to the windings 31a and 32a of the transformers 31 and 32 is reduced by connecting the windings 31a and 32a of the transformers 31 and 32 in series. . As a result, the transformers 31 and 32 can be downsized, and the loss in the winding resistance of the windings 31a and 32a can be reduced. Furthermore, by parallelizing the secondary circuit, the current flowing through each circuit can be distributed, and the loss generated in each secondary circuit is a multiplier of the resistance of the element or wiring and the square of the current. There is an effect that the loss is reduced by parallelizing the next circuit.

  Next, the structure of the DC / DC power converter device which becomes the 2nd Embodiment of this invention is demonstrated using FIG. In this embodiment, the present invention is applied to a DC / DC power conversion apparatus in which a primary circuit is a half bridge type and primary windings of a plurality of transformers are connected in parallel.

  In FIG. 5, a primary winding 31a of a first transformer 31 and a primary winding 32a of a second transformer 32 are connected in parallel to the primary circuit. As in FIG. 1, the output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are taken out from between the first half-bridge circuit 200, the second half-bridge circuit 210, and the output terminal 40b. It is. The output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are added by the adder 43 to obtain the total output amount.

  The total output amount obtained by the adder 43 is sent to the apportioning controller 44 and divided by the number of transformers 31 and 32 to obtain an equal output amount. Further, the apportioning controller 44 is configured such that the output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are individually input in parallel. Therefore, the proportional distribution control 44 outputs the equal output amount and the output amounts of the first half bridge circuit 200 and the second half bridge circuit 210, respectively. The equal output amount output from the proportional distribution controller 44 and the output amounts of the respective half bridge circuits 200 and 210 are input to the first comparator 45 and the second comparator 46. Further, the output amount of the first half-bridge circuit 200 is input to the first comparator 45, and the output amount of the second half-bridge circuit 210 is input to the second comparator 45.

  Accordingly, in each of the comparators 45 and 46, if the output amount is larger than the equal output amount, a comparison output signal for reducing the output amount is output, and if the output amount is smaller than the equal output amount, the output amount is set. A comparison output signal for enlarging is output. The comparison output signal of the first comparator 45 is input to the first switching element controller 47 that controls the switching elements 201 and 202 of the first half-bridge circuit 200, and the comparison of the second comparator 46 is performed. The output signal is input to the second switching element controller 48 that controls the switching elements 211 and 212 of the second half-bridge circuit 210. These switching element controllers 47 and 48 adjust the energization phase timing when each switching element 201, 202, 211, and 212 is switched ON and the energization phase amount that is the energization time to adjust each half. The output amount of the bridge circuits 200 and 210 can be controlled.

  As described above, the present embodiment can achieve the same effects as the first embodiment, and the currents of the transformers 31 and 32 are dispersed by connecting the primary windings 31a and 32a of the transformer in parallel. As a result, the loss in the transformer winding can be reduced. obtain.

  Next, the configuration of a DC / DC power converter according to a third embodiment of the present invention will be described with reference to FIG. In this embodiment, the present invention is applied to a DC / DC power converter in which a primary circuit is a full bridge type and primary windings of a plurality of transformers are connected in series.

  The full-bridge type DC / DC power converter is obtained by replacing the capacitors 23 and 24 in the primary circuit of FIG. 1 with a third switching element 23a and a fourth switching element 24a. The other configuration is substantially the same as the configuration shown in FIG. Note that the same gate signal waveform is applied to the first switching element 27 and the third switching element 23a, and the same gate signal waveform is applied to the second switching element 28 and the fourth switching element 24a. ON / OFF operation is repeated. Here, the two gate signals do not turn ON or OFF at the same time, and repeat ON / OFF operations.

  2A shows signal waveforms of the first switching element 27 and the fourth switching element 24a, and FIG. 2B shows signal waveforms of the second switching element 28 and the third switching element 23a. It is a thing. (C) and (d) show driving waveforms of the first switching element 201 and the second switching element 202 of the first half-bridge circuit 200, and (e) and (f) show the second half-bridge circuit. The drive waveforms of 210 first switching element 211 and second switching element 212 are shown. (G) shows the current waveform of the primary winding 31a of the first transformer 31 and the primary winding 32a of the second transformer 32. The operation of the secondary circuit of each of the transformers 31 and 32 is substantially the same as the configuration shown in FIG.

  The current flowing through the primary winding 31a of the first transformer 31 and the primary winding 32a of the second transformer 32 will be described. At time T0 to T1 in FIG. 2, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are turned on, and the second switching element 28 and The third switching element 23 a is in an off state, and the DC power source 21 is applied to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32.

  Next, at time T1 to T2, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are in the on state, and the second switching element 28 and The third switching element 23 a is in an off state, and the DC power source 21 is applied to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32.

  Next, at times T2 to T3, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are in the on state, and the second switching element 28 and The third switching element 23 a is in an off state, and the DC power source 21 is applied to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32.

  Next, at times T3 to T4, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are turned off, and the second switching element 28 and The third switching element 23 a is in an off state, and no voltage is applied to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32.

  Next, at times T4 to T5, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are in the off state, and the second switching element 28 and The third switching element 23 a is turned on, and the DC power source 21 applies a voltage in the reverse direction to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32.

  Next, at time T5 to T6, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are in the OFF state, and the second switching element 28 and The third switching element 23a is in an ON state, and the DC power source 21 is applied to the primary winding 31a of the first transformer 31 and the primary winding 32a of the second transformer 32 in the opposite directions.

  Next, at times T6 to T7, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are in the off state, and the second switching element 28 and the third switching element 28 The switching element 23a is turned on, and the DC power source 21 is applied to the primary winding 31a of the first transformer 31 and the primary winding 32a of the second transformer 32 in the opposite directions.

  Next, at times T7 to T8, as shown in FIGS. 2A and 2B, the first switching element 27 and the fourth switching element 24a are in the off state, and the second switching element 28 and The third switching element 23 a is turned off, and no voltage is applied to the primary winding 31 a of the first transformer 31 and the primary winding 32 a of the second transformer 32.

  Thus, the primary winding 31a of the transformers 31 and 32 is controlled by controlling the first switching element 27 and the third switching element 23a, and the second switching element 28 and the fourth switching element 24a. The primary current of 32a is controlled.

  As in FIG. 1, the output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are taken out from between the first half-bridge circuit 200, the second half-bridge circuit 210, and the output terminal 40b. It is. The output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are added by the adder 43 to obtain the total output amount.

  The total output amount obtained by the adder 43 is sent to the apportioning controller 44 and divided by the number of transformers 31 and 32 to obtain an equal output amount. Further, the apportioning controller 44 is configured such that the output amounts of the first half-bridge circuit 200 and the second half-bridge circuit 210 are individually input in parallel. Therefore, the proportional distribution control 44 outputs the equal output amount and the output amounts of the first half bridge circuit 200 and the second half bridge circuit 210, respectively. The equal output amount output from the proportional distribution controller 44 and the output amounts of the respective half bridge circuits 200 and 210 are input to the first comparator 45 and the second comparator 46. Further, the output amount of the first half-bridge circuit 200 is input to the first comparator 45, and the output amount of the second half-bridge circuit 210 is input to the second comparator 45.

  Therefore, each of the comparators 45 and 46 outputs an output signal for reducing the output amount if the output amount is large with respect to the equal output amount, and increases the output amount if the output amount is small with respect to the equal output amount. To output an output signal. The output signal of the first comparator 45 is input to the first switching element controller 47 that controls the switching elements 201 and 202 of the first half bridge circuit 200, and the output signal of the second comparator 46. Is input to the second switching element controller 48 that controls the switching elements 211 and 212 of the second half-bridge circuit 210. These switching element controllers 47 and 48 adjust the energization phase timing when each switching element 201, 202, 211, and 212 is switched ON and the energization phase amount that is the energization time to adjust each half. The output amount of the bridge circuits 200 and 210 can be controlled.

  As described above, this embodiment can achieve the same effect as that of the first embodiment. In addition, in this embodiment, the primary circuit is a full bridge circuit, so that the voltage applied to the transformer is twice that of the half bridge circuit. Therefore, it becomes possible to transmit more power to the secondary circuit, and it becomes possible to cope with the high power and high power density of the DC / DC power converter.

  Further, by connecting the windings 31a and 32a of the transformers 31 and 32 in series, the voltage applied to the windings 31a and 32a of the transformers 31 and 32 is reduced. As a result, the transformers 31 and 32 can be reduced in size, and the loss in the winding resistance of the windings 31a and 32a can be reduced. Furthermore, by parallelizing the secondary circuit, the current flowing through each circuit can be distributed, and the loss generated in each secondary circuit is a multiplier of the resistance of the element or wiring and the square of the current. There is an effect that the loss is reduced by parallelizing the next circuit.

  Next, the structure of the DC / DC power converter device which becomes the 4th Embodiment of this invention is demonstrated using FIG. 7, FIG. In the present embodiment, a plurality of DC / DC power converters described in the first embodiment are used, and only two DC / DC power converters are used here, and the primary circuit and secondary circuit of each DC / DC power converter are connected in parallel. A multi-phase method is applied. As shown in FIG. 7, the primary circuit and the secondary circuit of the first DC / DC power converter 6 are connected to the positive electrode and the negative electrode of the DC power supply 21, and similarly the primary circuit of the second DC / DC power converter 7. The circuit and the secondary circuit are connected to the positive electrode and the negative electrode of the DC power source 21. The operations of the two DC / DC power converters 6 and 7 are as follows.

  8A shows the gate signal waveform of the switching element 27 on the high side of the primary circuit of the first DC / DC power converter 6, and FIG. 8B shows the first DC / DC power converter 6. 5C shows a gate signal waveform of the switching element 201 on the high side of the first half-bridge circuit 200, and (c) shows the high-side side of the second half-bridge circuit 210 of the first DC / DC power converter 6. The gate signal waveform of the switching element 211 is shown.

  Similarly, (d) shows the gate signal waveform of the switching element 27 on the high side of the primary circuit of the second DC / DC power converter 7, and (e) shows the second DC / DC power converter 7. The gate signal waveform of the switching element 201 of the high side of the 1st half bridge circuit 200 is shown, (f) is switching of the high side of the 2nd half bridge circuit 210 of the 2nd DC / DC power converter device 7. The gate signal waveform of the element 211 is shown.

  Further, (g) shows the current waveform flowing in the choke coil of the first DC / DC power converter 6, and (h) shows the current waveform flowing in the choke coil of the second DC / DC power converter 7. Yes. (I) is a combined current of the first DC / DC power converter 6 and the second DC / DC power converter, that is, a current waveform flowing in the choke coil of the first DC / DC power converter 6; It is the sum of current waveforms flowing in the choke coil of the second DC / DC power converter 7.

  In the present embodiment, each switching element of the second DC / DC power converter 7 based on the gate signal waveforms (a) to (c) of each switching element of the first DC / DC power converter 6. Are delayed by the phase θ. For example, in FIG. 8, the second DC / DC shown in (d) with respect to the gate signal waveform of the switching element 27 on the high side of the primary circuit of the first DC / DC power converter 6 shown in (a). The gate signal waveform of the switching element 27 on the high side of the primary circuit of the power converter 7 is shifted by the phase θ. Similarly, with respect to the gate signal waveform of the switching element 201 on the high side of the first half-bridge circuit 200 of the first DC / DC power converter 6 shown in (b), the second signal shown in (e). The one-gate signal waveform of the switching element 211 on the high side of the first half-bridge circuit 200 of the DC / DC power converter 7 is shifted by a phase θ, and the first DC / DC power converter shown in FIG. For the gate signal waveform of the switching element 211 on the high side of the sixth second half-bridge circuit 210, the second half-bridge circuit 210 of the second DC / DC power converter 7 shown in FIG. The gate signal waveform of the switching element 211 on the side side is shifted by the phase θ.

  As a result, the phase difference between the current flowing through the choke of the first DC / DC power converter 6 and the current flowing through the chocoil of the second DC / DC power converter 7 becomes θ. Accordingly, the combined output currents are combined with each other's ripple current, and the total output ripple current of the DC / DC power converter is reduced. Thereby, it is possible to provide a stable DC voltage to the load. Furthermore, since it is driven in parallel, it is possible to provide a high-power DC / DC power converter.

  In the embodiment described above, the number of transformers has been described as two. However, the number of transformers is not limited to this number. Three or more transformers are used, and these are connected in series or connected in parallel. Then it is good. Further, the value of the turn ratio of the primary winding and the secondary winding of each transformer may be different.

  Summarizing the present invention, in the present invention, the total output amount obtained by adding the output amounts of the secondary circuits provided for each of a plurality of transformers is divided by the number of transformers to obtain an equal output amount. The switching amount of each secondary circuit is controlled such that the output amount of each circuit is compared and the output amount of each secondary circuit converges to an equal output amount. As a result, since the primary circuit is shared by a plurality of transformers, the loss or cost of the primary circuit can be reduced, and the output amount of the secondary circuit for each transformer can be made as close as possible to each other. become. Therefore, it is possible to correct the output imbalance among the individual secondary circuits corresponding to each transformer due to variations in the elements and wiring of each secondary circuit and changes in the element characteristics due to temperature. is there.

  DESCRIPTION OF SYMBOLS 1 ... DC / DC power converter device 21 ... Input DC voltage, 22a, 22b ... Input terminal, 23 ... 1st capacitor | condenser, 24 ... 2nd capacitor | condenser, 27 ... 1st switching element, 28 ... 2nd switching Elements 31 ... first transformer 31a ... primary winding of first transformer 31b ... secondary winding of first transformer 32 ... second transformer 32a ... primary winding of second transformer, 32b ... secondary winding of second transformer, 35 ... first choke coil, 36 ... smoothing capacitor, 39 ... second choke coil, 40a, 40b ... output terminal, 41 ... load, 42 ... resonant coil, 43 ... Adder circuit, 44 ... Prorated control circuit, 45, 46 ... Comparator, 47 ... Switching element controller, 200 ... First half-bridge circuit 200, 201 ... First switching element, 202 ... Second switching Elements 203 ... first capacitor 204 ... second capacitor 210 ... second half bridge circuit 211 ... first switching element 212 ... second switching element 213 ... first capacitor 214 ... Second capacitor.

Claims (10)

In an insulated power converter that obtains a DC output by converting the DC input power using a plurality of transformers,
A primary circuit commonly used for the plurality of primary windings for commonly controlling a primary current flowing in the plurality of primary windings wound around the plurality of transformers;
Secondary circuits individually used for the plurality of secondary windings to control secondary currents flowing through the plurality of secondary windings wound around the plurality of transformers;
The total output amount obtained by adding the actual output amount of the secondary circuit provided for each of the plurality of transformers is divided by the number of transformers to obtain an equal output amount. The equal output amount and the actual output amount of the secondary circuit And an output adjustment unit that adjusts the output amount of each secondary circuit so that the output amount of each secondary circuit converges to an equal output amount. The power conversion device according to claim 1,
The output adjusting unit is
An addition function unit for adding the output amounts of the individual secondary circuits to obtain a total output amount; and
A distribution function unit for dividing the total output amount obtained by the addition function unit by the number of the transformers to obtain an equal output amount of each of the secondary circuits;
A comparison function unit that compares the equal output amount obtained by the apportioning function unit with an actual output amount of each of the secondary circuits, and outputs a comparison result;
An electric power conversion apparatus comprising: an output variable function unit that converges an output amount of each of the secondary circuits to the equal output amount based on a comparison result of the comparison function unit. The power conversion device according to claim 2,
Each of the secondary circuits is a half bridge comprising at least two switching elements having one end of the secondary winding connected therebetween, and two capacitors having the other end of the secondary winding connected therebetween. A circuit and a choke coil connected to the output end of the half-bridge circuit,
The output variable function unit adjusts gate signals of the two switching elements to converge the output amounts of the individual secondary circuits to the equal output amount. The power conversion device according to claim 3,
The variable output function unit adjusts the energization phase amount, which is the energization time of the gate signals of the two switching elements, or the energization phase timing, which is the ON timing of the two switching elements. A power converter that converges an output amount of a circuit to the equal output amount. The power conversion device according to claim 1,
The output adjusting unit is
An addition function unit for adding the current values of the individual secondary circuits to obtain a total current value;
A distribution function unit for dividing the total current value obtained by the addition function unit by the number of the transformers to obtain an equal current value of each of the secondary circuits;
A comparison function unit that compares the equal current value obtained by the apportioning function unit with an actual current value of each of the secondary circuits, and outputs a comparison result;
A power conversion device comprising: an output variable function unit that converges the current value of each of the secondary circuits to the equal current value based on a comparison result of the comparison function unit. The power conversion device according to claim 5,
The primary circuit is a circuit that connects primary windings of a plurality of transformers and converts a direct current formed of at least two switching elements into an alternating current,
In each of the secondary circuits, one end of the secondary winding of the transformer is connected between two switching elements, and the other end of the secondary winding of the transformer is connected between two capacitors. A circuit comprising a half bridge circuit and a choke coil connected to the output end of the half bridge circuit,
The current from the output terminal of each individual secondary circuit is added by the addition function unit to obtain a total current value,
The total current value obtained by the addition function unit is divided by the number of the transformers by the apportioning function unit to obtain an equal current value of each individual secondary circuit,
The equal current value obtained by the apportioning function unit is compared with the actual current value of the individual secondary circuit in the comparison function unit, and a comparison result is output.
Based on the comparison result obtained by the comparison function unit, the output variable function unit controls the gate signals of the two switching elements to converge the current values of the individual secondary circuits to the equal current values. The power converter characterized by this. The power conversion device according to claim 6, wherein
The primary windings of the plurality of transformers are connected to each other in series and connected to the primary circuit, or connected in parallel to each other and connected to the primary circuit. The power conversion device according to claim 6, wherein
The primary circuit is connected in series with the two switching elements connected in series and a half-bridge circuit composed of two capacitors connected in series, or with the two switching elements connected in series. A power conversion device, which is a full-bridge circuit in which the two capacitors are replaced with switching elements.   A plurality of power converters according to any one of claims 1 to 8 are used, and the power converters are connected in parallel to a DC power source, and the output terminals of the power converters are combined and output. The power converter characterized by doing. The power conversion device according to claim 9, wherein
The power converter according to claim 1, wherein the secondary circuit of each power converter is controlled in phase by shifting a phase of the secondary circuit.

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