JPWO2020129143A1 - Power converter - Google Patents

Abstract

Outputs of multiple inverters (INV1 to INVn) using a transformer (4) with multiple windings composed of one core for the purpose of increasing the high voltage and high output of the power converter and reducing the size and loss of the transformer. Are connected in parallel to the primary windings (411-41n), the secondary windings (421a, 421b-42ma, 42mb) are connected in series after rectification, and the inverters (INV1 to INVn) are interleaved according to the input voltage. Change the number of drives, or switch between interleave and in-phase drive to operate.

Description

The present application relates to a power converter.

For example, as devices that require high voltage, there are an X-ray CT device and an X-ray imaging device, which irradiate a subject with X-rays generated from an X-ray tube and detect an X-ray dose transmitted through the subject. It is to be imaged. In such a device, a high DC voltage is applied between the anode and cathode of the X-ray tube to accelerate the thermions generated by raising the temperature of the cathode at a high voltage, which collide with the cathode to emit X-rays. It is occurring.

In order to obtain this high voltage, for example, as shown in Patent Document 1, the output of the inverter is connected to a transformer connected in parallel, the transformer output is connected in series after rectification, and a high voltage is obtained at the electrode of the load. The configuration is taken.
Further, as shown in Patent Document 2, an LC resonance circuit is provided in order to reduce the size of the transformer while absorbing variations in input voltages input from a plurality of power supply lines, and magnetically coupled with one core. A switching power supply with multiple transformers is shown.

Japanese Unexamined Patent Publication No. 2013-30325 JP-A-2017-77078

The power supply device shown in Patent Document 1 is configured to connect the output of an inverter to a transformer connected in parallel, connect the transformer output in series after rectification, and obtain a high voltage at the electrode of the load. However, the idea of downsizing the transformer has not been shown.

In the configuration of Patent Document 2, a circuit that magnetically integrates a plurality of transformers into one core to obtain a high voltage on the secondary side and an idea of reducing the size of the transformer by magnetically integrating the transformers are shown. No idea has been given to further miniaturize the magnetically integrated transformer.
Further, neither Patent Document 1 nor Patent Document 2 describes a surge suppression method that causes a problem when the loss of the power conversion device is reduced, the power is increased, or the output voltage is increased.

The present application has been made to solve the above-mentioned problems, and it is possible to increase the power by reducing the loss of the power converter, suppress the surge, enable high voltage output, and transform the transformer. The purpose is to provide a power conversion device that can be miniaturized.

The power converter disclosed in the present application is
N DC / AC converters for AC conversion of DC power supply (N is an integer of 2 or more),
N primary windings connected to each of the N DC / AC converters and M secondary windings magnetically coupled to the N primary windings (M is an integer of 2 or more). Transformer,
M rectifier circuits that are connected to a transformer and rectify the output from the transformer to direct current and output it.
A control circuit that controls the DC / AC converter,
With
The DC terminals of the M rectifier circuits are connected to each other.
The control circuit is characterized in that N DC / AC converters are interleaved driven with their phases shifted.

Further, the power conversion device disclosed in the present application is:
A transformer composed of N primary windings (N is an integer of 2 or more) and M secondary windings (M is an integer of 2 or more) wound around one core.
N DC / AC converters that are connected to N primary windings and convert DC power to AC.
The input side is connected to M secondary windings, and M rectifier circuits that rectify the output from the transformer to direct current and output it.
A control circuit that controls the DC / AC converter,
With
The control circuit is characterized in that N DC / AC converters are switched between interleaved drive and in-phase drive, which are out of phase with each other, according to the voltage of the DC power supply.

Since the DC / AC converter is operated with the phase shifted, the transformer can be driven at a frequency higher than the switching frequency of the DC / AC converter, and the transformer core can be operated without raising the switching frequency of the DC / AC converter. Can be miniaturized.
Further, the iron loss can be reduced by switching between the interleave drive and the in-phase drive according to the input voltage.

It is a circuit block diagram of the power conversion apparatus according to Embodiment 1. It is a figure which shows an example of the hardware composition of a control circuit. It is a figure explaining the operation waveform of the power conversion apparatus according to Embodiment 1. It is a figure explaining the current path at the time of operation by Embodiment 1. FIG. It is a figure explaining the output waveform of the filter circuit by Embodiment 1. FIG. It is a figure explaining another current path at the time of operation by Embodiment 1. FIG. It is a circuit block diagram of the power conversion apparatus according to Embodiment 2. It is a figure which shows the relationship of the duty of the DC / AC conversion part in the power conversion apparatus according to Embodiment 3. It is a figure which shows the operation waveform of the switching operation of the power conversion apparatus according to Embodiment 3.

Hereinafter, preferred embodiments of the power conversion device according to the present application will be described with reference to the drawings. The same contents and corresponding parts are designated by the same reference numerals, and detailed description thereof will be omitted. Similarly, in the following embodiments, duplicate description of the configurations with the same reference numerals will be omitted.

Embodiment 1.
FIG. 1 is a diagram showing a circuit configuration of a power conversion device according to the first embodiment. As shown in FIG. 1, the DC voltage source 1 is input to the DC / AC converter 3 via the link capacitor 2. The DC / AC converter 3 is composed of a plurality of bridge-type inverters that are DC / AC converters, and has a configuration in which n inverters INV1 to INVn are connected in parallel. The inverter INV1 is composed of switching elements SW11 to SW14, and the inverter INVn is composed of switching elements SWn1 to SWn4.

The AC outputs of the inverters INV1 to INVn constituting the DC / AC converter 3 are obtained by winding a plurality of (n in this example) primary windings and a plurality of secondary windings (m in this example) on one core. It is connected to the primary windings 411 to 41n of the transformer 4 magnetically coupled to each other. The plurality of secondary windings of the transformer 4 are composed of center taps, and the first winding is the secondary winding 421a, 421b, and the mth winding is the secondary winding 42ma, 42mb. To do.

A rectifier circuit 5 having a common anode is connected to the secondary windings 421a, 421b to 42ma, and 42mb, and a filter circuit 6 is connected to the output of the center tap.

Explaining the details of the connection by taking the first secondary windings 421a and 421b as an example, the cathodes of the rectifying elements 51a and 51b constituting the rectifying circuit 5 are connected to the secondary windings 421a and 421b, and the center tap is used. The smoothing reactor 61a of the filter circuit 6 is connected to the output, and the smoothing capacitor 61b is connected to the output of the smoothing reactor 61a.

The output of the smoothing capacitor 61b is connected to the anodes of the rectifying elements 51a and 51b and the connection point between the smoothing reactor and the smoothing capacitor connected to the second secondary winding. By repeatedly connecting the m secondary windings provided in the transformer 4 and the m rectifier circuits, the m DC side terminals are connected to each other. The load 7 is connected to the connection point between the first smoothing reactor 61a and the smoothing capacitor 61b and the connection point between the mth smoothing reactor 6ma and the smoothing capacitor 6mb.

In the control circuit 10, the voltage of the load 7 is set to a predetermined voltage based on the outputs of the input voltage sensor 8 and the output voltage sensor 9, so that the phase of the inverter group constituting the DC / AC converter 3 is n-phase. The duty of each inverter is controlled by shifting the voltage (interleave drive control).

An example of the hardware of the control circuit 10 is shown in FIG. It is composed of a processor 100 and a storage device 101, and although not shown, the storage device 101 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. Further, an auxiliary storage device of a hard disk may be provided instead of the flash memory. The processor 100 executes a program input from the storage device 101, and executes a part or all of the interleave drive control or the switching between the interleave drive and the in-phase drive described later. In this case, a program is input from the auxiliary storage device to the processor 100 via the volatile storage device. Further, the processor 100 may output data such as a calculation result to the volatile storage device of the storage device 101, or may store the data in the auxiliary storage device via the volatile storage device. Further, in addition to the processor 100 and the storage device 101, a logic circuit and an analog circuit may be used in combination.

The inverters INV1 and INV2 (n = 2) of the DC / AC converter 3, the primary windings 411 and 412 (n = 2) of the transformer 4, and the secondary windings 421a, 421b and 422a of the transformer 4 described with reference to FIG. The operation waveform of each part when 422b (m = 2) is set will be described with reference to FIG.

FIG. 3A shows the voltage of the DC voltage source 1 and the voltage of the load 7 which is the output, and the voltage of the DC voltage source 1 is 400 V and the voltage of the load 7 is about 420 V.
FIG. 3B shows the drive timing of the inverter INV1 of the DC / AC converter 3, and shows the operation timings of the switching elements SW11 and SW13 of the upper arm on the bridge side.
FIG. 3C shows the drive timing of the inverter INV2 of the DC / AC converter 3, and shows the operation timings of the switching elements SW21 and SW23 of the upper arm on the bridge side.
As can be seen from FIGS. 3B and 3C, the inverter INV1 and the inverter INV2 are divided into two in one cycle and are operated with a phase shift of 180 degrees. When the number of inverters is N-phase, one cycle is divided into n, and each is interleaved driven by shifting the 360-degree / n phase.

FIG. 3D shows the voltage of the primary winding 411 of the transformer 4, and FIG. 3E shows the voltage of the primary winding 412 of the transformer 4. In the case of FIG. 3D, the inverter INV1 operates on / off only in 1/2 cycle within one cycle, a voltage is generated in the primary winding 411 of the transformer 4, and the inverter INV1 does not operate on / off in 2/2 cycles. However, since the primary winding 411 of the transformer 4 and the primary winding 412 are coupled, a voltage is generated in the primary winding 411 of the transformer 4 even in the 2/2 cycle in which the inverter INV2 operates.

Similarly in the case of FIG. 3E, the inverter INV2 operates on and off only in 2/2 cycles within one cycle, a voltage is generated in the primary winding 412 of the transformer 4, and 1/2 cycle of the inverter INV2 is turned on and off. Although it does not operate, since the primary winding 411 of the transformer 4 and the primary winding 412 are coupled, a voltage is generated in the primary winding 412 of the transformer 4 even in the 1/2 cycle in which the inverter INV1 operates.

In this way, a voltage is generated in the primary windings 411 and 412 of the transformer 4 even when not switching, but if the number of turns of the primary windings 411 and 412 is the same, for example, when the inverter INV1 is operating, The inverter INV2 does not rectify and draw the load current into the DC voltage source 1, and the power from the DC voltage source 1 passes through the secondary windings 421a, 421b, 422a, and 422b of the transformer 4 to the load 7. Be transmitted.

As described above, when the inverters INV1 and INV2 perform interleave drive switching in which the phases are alternately shifted by 180 degrees, the drive frequency of the transformer 4 can be doubled the drive frequency of the inverters INV1 and INV2. That is, since one cycle is time-divided by the two phases of the inverter and the voltage is alternately applied to the transformer 4, the VT product (V is the applied voltage and T is the time during which the voltage is applied to the primary winding) is halved. Therefore, the core of the transformer 4 can be made smaller. Therefore, in order to reduce the core of the transformer 4, it is not necessary to increase the drive frequencies of the inverters INV1 and INV2, and the switching loss can be reduced.
Similarly, when the n-phase inverters are operated alternately, the VT product becomes 1 / n, and the core of the transformer 4 can be further miniaturized.

FIG. 3F shows the current of the primary winding 411 of the transformer 4, and FIG. 3G shows the current of the primary winding 412 of the transformer 4. In FIG. 3F, the current flows only in the 1/2 cycle in which the inverter INV1 is operating (timing shown in FIG. 3B), and in FIG. 3G, the current flows only in the 2/2 cycle in which the inverter INV2 is operating (timing shown in FIG. 3C). Indicates that current flows. That is, it can be seen that when the inverter is operated in two phases, the current application time is halved.
Therefore, when the inverter is composed of n phases, the current application time is 1 / n, and by increasing the number of phases, the average current and the current effective value per inverter can be reduced, and the copper loss of the inverter can be reduced. Therefore, the loss of the DC / AC converter 3 can be reduced.

FIG. 3H shows the current flowing through the smoothing reactor 61a, and the ripple frequency of the current is 2n times the switching frequency of the inverter constituting the DC / AC converter 3 (4 times when the inverter has two phases), and the current ripple is small. In addition, since the current ripple frequency can be increased, the capacitances of the smoothing reactors 61a to 6ma and the smoothing capacitors 61b to 6mb of the filter circuit 6 can be reduced.

Next, the operation of the power converter will be described. FIG. 4 shows a current path when the switching element SW11 and the switching element SW14 of the inverter INV1 are on. The current on the primary side of the transformer 4 is a path that returns to the DC voltage source 1 by obtaining the switching element SW11, the primary winding 411, and the switching element SW14 from the DC voltage source 1. A voltage is generated in the other primary windings of the transformer 4, but since the number of turns of the primary windings is the same, a voltage that constantly exceeds the DC voltage source 1 is not constantly generated, and the load current is applied to the remaining inverters INV2 to INVn. Does not flow.

A voltage is generated in the secondary windings 421a, 421b to 42ma, and 42mb of the transformer 4 according to the turns ratio of the primary winding and the secondary winding of the transformer 4, and the rectifying elements 51b to 5mb in the rectifier circuit 5 are conducted. , A current flows from the center tap point toward the smoothing reactor 61a to 6ma. The filter circuits 6 connected to each of the secondary windings are connected in series, and a voltage m times the voltage per stage after the filter is applied to the load 7.

When the impedance of the smoothing reactors 61a to 6ma of the filter circuit 6 is set to a value sufficiently lower than that of the load 7, the current including the current ripple is, for example, the secondary winding of the transformer 4, as shown by the middle dotted line in FIG. The current circulates through the wire 421b, the smoothing reactor 61a, and the smoothing capacitor 61b, and only the DC component including an extremely small current ripple flows through the load 7.

FIG. 5 shows the current waveforms of the smoothing reactor 61a, the smoothing capacitor 61b, and the load 7 when two-phase parallel driving is performed using the inverters INV1 and INV2.
5A shows the input / output voltage of the power converter as in FIG. 3A, FIG. 5B shows the drive timing of the inverter INV1 as in FIG. 3B, FIG. 5C shows the drive timing of the inverter INV2 as in FIG. 3C, and FIG. 5D shows the drive timing of the inverter INV2. Similar to FIG. 3H, the smoothing reactor 61a and the current of the load 7 are shown, and FIG. 5E shows the current of the smoothing capacitor 61b.
The frequency of the current ripple flowing through the smoothing reactor 61a is a current containing a ripple component having a frequency four times the switching frequency for driving the inverter INV1 and the inverter INV2, but the impedance of the smoothing capacitor 61b is made sufficiently small with respect to the load 7. If this is done, this current ripple component will almost flow into the smoothing capacitor 61b, circulate through the secondary winding 421b of the transformer 4 and the smoothing reactor 61a, and will not appear in the load 7.

Next, FIG. 6 shows a current path when the switching element SW13 and the switching element SW12 of the inverter INV1 are on. The current on the primary side of the transformer 4 is a path that returns to the DC voltage source 1 by obtaining the switching element SW13, the primary winding 411, and the switching element SW12 from the DC voltage source 1. A voltage is generated in the other primary windings of the transformer 4, but since the number of turns of the primary windings is the same, a voltage that constantly exceeds the DC voltage source 1 is not constantly generated, and the load current is applied to the remaining inverters INV2 to INVn. Does not flow.

A voltage is generated in the secondary windings 421a, 421b to 42ma, and 42mb of the transformer 4 according to the turns ratio of the primary winding and the secondary winding of the transformer 4, and the rectifying elements 51a to 5ma in the rectifier circuit 5 conduct. A current flows from the center tap point toward the smoothing reactors 61a to 6ma, and the filter circuit 6 connected in series applies a voltage m times the voltage per stage after the filter to the load 7. Further, since the voltage applied to each of the rectifying elements 51a to 5ma in the rectifying circuit 5 can be reduced, the surge voltage can also be reduced.

When the impedance of the smoothing reactors 61a to 6ma of the filter circuit is set to a value sufficiently lower than that of the load 7, the current including the current ripple is, for example, the secondary winding 421b of the transformer 4 as shown by the dotted line in the figure. , The smoothing reactor 61a and the smoothing capacitor 61b circulate, and only the DC component including a very small current ripple flows through the load 7.
The description of the current is omitted because it is as described in FIG. 5 except that the location where the secondary winding of the transformer flows is different.

When the other inverters INV2 to INVn connected in parallel in the DC / AC converter 3 are operated with the phases shifted, the same current path and operation as described above are obtained.

As described above, the power conversion device of the present embodiment has the following effects, and a high output and high voltage power supply can be realized with low loss and small size.
(1) When the phase is shifted, the drive frequency of the transformer can be N times the drive frequency of the DC / AC conversion unit, so that the VT product of the transformer can be reduced and the core can be miniaturized.
(2) Since the current application time of the DC / AC conversion unit can be dispersed to 1 / N, the copper loss is small.
(3) In order to reduce the core of the transformer, it is not necessary to increase the drive frequency of the DC / AC converter, and the switching loss is small.
(4) Since the rectified voltage is connected in series to obtain the output voltage, the rectified voltage per stage is small, so the surge voltage is small, the loss is reduced by eliminating the surge circuit, and the rectified circuit is inexpensive and has a low withstand voltage. A high voltage output circuit can be configured with the element.
(5) Since the phase of the DC / AC conversion unit is shifted to perform the interleave operation, the output current ripple is increased in frequency and becomes smaller, and the filter circuit can be made smaller.

Embodiment 2.
In the first embodiment, the secondary side configuration of the transformer 4 is connected in series with the outputs of the individual filters in the filter circuit 6 to output a high voltage to the load 7, but the second embodiment is rectified. The output of the circuit 5 is connected in series to generate a high voltage to the load 7.

The configuration of the second embodiment will be described with reference to FIG. Since the configurations of the primary windings 411 to 41n of the transformer 4 are the same as those in the first embodiment, they are omitted. The anodes of the rectifying elements 51a and 51b constituting the rectifying circuit 5 are connected, and this is connected to the center tap point of the secondary winding of the transformer 4 in the next stage. The same connection is repeated m-1 times in total to connect the m-stage rectifier circuit in series. In FIG. 7, the rectifier circuit between the first-stage rectifier circuit composed of the rectifier elements 51a and 51b and the m-th stage rectifier circuit composed of the rectifier elements 5ma and 5 mb is omitted.

A smoothing reactor 61a is connected to the center tap points of the first-stage secondary windings 421a and 421b, which are the output ends of the rectifier circuit 5 connected in series, and the anode connection points of the m-th stage rectifier elements 5ma and 5mb. A filter circuit 6 including a smoothing capacitor 61b is connected, and a load 7 is connected to the output of the filter circuit 6.

With such a configuration, the voltage across the smoothing reactor 61a constituting the filter circuit 6 becomes high, so that the current ripple flowing through the smoothing reactor 61a and the smoothing capacitor 61b becomes large. If this can be tolerated, the first embodiment 1 Since the number of smoothing reactors and smoothing capacitors can be reduced as compared with the above, the power conversion device can be further miniaturized. That is, although the current ripple increases as compared with the first embodiment, the filter circuit 6 becomes smaller, and the same effects as those of the first embodiment can be obtained with respect to other effects.

Embodiment 3.
The power conversion device of the third embodiment has the same configuration as that of the first embodiment or the second embodiment, and has an interleave drive for operating the inverters INV1 to INVn constituting the DC / AC converter 3 with the phase shifted, and the inverter INV1. The so-called in-phase drive in which ~ INVn is operated in the same phase is switched and operated according to the voltage of the DC voltage source 1.

FIG. 8 shows the relationship between the load voltage when the load 7 is a rechargeable battery or the like and charging proceeds and the duty of the inverters INV1 to INVn constituting the DC / AC converter 3.
When the voltage Vin of the DC voltage source 1 is constant, the voltage of the load 7 is low at the initial stage of charging, so the DC / AC converter 3 throttles the duty based on the command of the control circuit 10 and averages the voltage on the secondary side of the transformer 4. Adjust and charge. As charging progresses and the charging voltage of the load 7 becomes higher, the control circuit 10 raises the average voltage on the secondary side of the transformer 4, so that the DC / AC converter 3 increases the duty to perform the charging operation (graph P). ..

In general, the efficiency of the power converter is improved when the DC / AC converter 3 is operated with the maximum duty so that the operating ratio of the transformer 4 is high, that is, the so-called current effective value is low. Therefore, the DC voltage source 1 is used. It is desired to perform maximum duty control such as charging while changing the voltage Vin (Graph Q). In this duty maximum control, the DC / AC converter 3 is interleaved in a state where the voltage of the DC voltage source 1 is low in the initial state of charging and the VT product has a margin (for example, period R), and the drive frequency of the transformer 4 is controlled. If left high, iron loss will be wasted. Therefore, when the voltage of the DC voltage source 1 is low (period R), the number of inverters to be interleaved driven by the DC / AC converter 3 (number of interleaved drives) is reduced, and the transformer 4 is driven when the DC / AC converter 3 is ultimately driven in phase. The frequency can be lowered.

At time t1, which satisfies the condition of the VT product that the transformer does not saturate and the condition that the iron loss decreases when the drive frequency of the transformer is lowered, the operation of the DC / AC converter 3 is changed to the interleave number of the interleave drive or the in-phase drive. By switching, iron loss can be suppressed and the power converter can be operated with high efficiency.

FIG. 9 describes the drive timing, duty, and switching operation between the inverter INV1 and INV2 and the in-phase drive when the DC / AC converter 3 is driven in two-phase parallel using the inverters INV1 and INV2.

FIG. 9A schematically shows the drive timing and duty of the interleaved drive inverters INV1 and 2 at the initial stage of charging when the voltage Vin of the DC voltage source 1 is fixed. At the initial stage of charging, since the charging voltage of the load 7 is low, the duty is reduced so as to lower the average voltage on the secondary side of the transformer 4, and power is transmitted to the secondary side of the transformer 4 during this short operation period. Therefore, the effective current value is high and the loss is large.

FIG. 9B schematically shows the drive timing and duty of each of the interleaved drive inverters INV1 and INV2 when charging is completed. Since the charging voltage of the load 7 is high, in order to raise the secondary side average voltage of the transformer 4, the duty is wide, the current effective value is suppressed to a low level, and high efficiency operation is performed. The constant duty control is a control in which the input voltage Vin of the DC voltage source 1 is made variable so that the duty becomes large. Since the input voltage Vin is variable, the number of interleave drives is variable.

FIG. 9C shows when the DC / AC converter 3 is driven in common mode when the voltage of the DC voltage source 1 at the initial stage of charging is low, the duty is opened to the maximum, and the core of the transformer 4 has a VT product that does not saturate. It is a figure of. In this case, the drive frequency of the transformer 4 is the same as the switching frequency of the inverters INV1 and INV2, and the frequency is lower than that during the interleave drive, so that the iron loss can be reduced.

As described above, the drive frequency of the transformer 4 can be changed by switching the number of interleaved drives or switching between the interleaved drive and the in-phase drive in the operation of the DC / AC converter 3 according to the voltage of the DC voltage source 1. By doing so, it is possible to obtain a power converter capable of downsizing and reducing the loss of the transformer, which is compatible with high power and high output voltage.

Although the present application describes various exemplary embodiments and examples, the various features, embodiments, and functions described in one or more embodiments are applications of a particular embodiment. It is not limited to, but can be applied to embodiments alone or in various combinations.
Therefore, innumerable variations not illustrated are envisioned within the scope of the techniques disclosed herein. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

1: DC voltage source, 2: Link capacitor, 3: DC / AC converter, INV1 to INVn: Inverter, SW11 to SWn4: Semiconductor switch, 4: Transformer, 411 to 41n: Primary winding, 421a, 421b to 42ma, 42mb: Secondary winding, 5: Rectifier circuit, 51a, 51b-5ma, 5mb: Rectifier element, 6: Filter circuit, 61a-6ma: Smoothing reactor, 61b-6mb: Smoothing capacitor, 7: Load, 8: Input voltage Sensor, 9: Output voltage sensor, 10: Control circuit

The power converter disclosed in the present application is
N DC / AC converters for AC conversion of DC power supply (N is an integer of 2 or more),
N primary windings connected to each of the N DC / AC converters and M secondary windings magnetically coupled to the N primary windings (M is an integer of 2 or more). Transformer,
M rectifier circuits that are connected to a transformer and rectify the output from the transformer to direct current and output it.
A control circuit that controls the DC / AC converter,
With
The DC terminals of the M rectifier circuits are connected to each other.
The control circuit drives N DC / AC converters in phase-shifted interleave drive .
The interleave drive is characterized in that the number of interleave drives of the DC / AC conversion unit is variable according to the voltage of the DC power supply .

Claims (10)

N DC / AC converters for AC conversion of DC power supply (N is an integer of 2 or more),
N primary windings connected to each of the N DC / AC converters and M secondary windings magnetically coupled to the N primary windings (M is an integer of 2 or more) Transformer with and
M rectifier circuits connected to the transformer and rectifying the output from the transformer to direct current and outputting it.
A control circuit that controls the DC / AC conversion unit,
With
The DC side terminals of the M rectifier circuits are connected to each other.
The control circuit is a power conversion device characterized in that the N DC / AC conversion units are interleaved driven with their phases shifted. The power conversion device according to claim 1, wherein the M rectifier circuits are connected via M filter circuits, and the M filter circuits are connected in series with each other. The first aspect of the present invention, wherein the M rectifier circuits are connected in series with each other, and both ends of the M rectifier circuits connected in series are connected to a load via a filter circuit. Power converter. The power conversion device according to any one of claims 1 to 3, wherein the interleaving drive changes the number of interleaving drives of the DC / AC conversion unit according to the voltage of the DC power supply. The power conversion device according to claim 4, wherein the interleave drive number is reduced when the voltage of the DC power supply is low, and iron loss is reduced when the transformer is not saturated and the drive frequency of the transformer is lowered. .. A transformer composed of N primary windings (N is an integer of 2 or more) and M secondary windings (M is an integer of 2 or more) wound around one core.
N DC / AC converters that are connected to N primary windings and convert DC power to AC.
The input side is connected to the M secondary windings, and the output from the transformer is rectified to direct current and output.
A control circuit that controls the DC / AC conversion unit,
With
The control circuit is a power conversion device characterized in that the N DC / AC conversion units are switched between interleaved drive and in-phase drive, which are out of phase with each other, according to the voltage of the DC power supply. The power conversion according to claim 6, wherein the M rectifier circuits are connected to each other via M filter circuits, and the M filter circuits are connected to each other in series. apparatus. The sixth aspect of claim 6, wherein the M rectifier circuits are connected in series with each other, and both ends of the M rectifier circuits connected in series are connected to a load via a filter circuit. Power converter. The invention according to any one of claims 6 to 8, wherein when the transformer is not saturated and the iron loss is reduced when the drive frequency of the transformer is lowered, the transformer is switched to the in-phase drive when the voltage of the DC power supply is low. The power converter described. The power conversion device according to any one of claims 1 to 9, wherein the number of turns of each of the N primary windings is the same.

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