JP2016220431A - Power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device in which a capacitor charge circuit is formed from a little components and which is adaptable to hot swap that enables, while an inverter and a converter of at least one power conversion unit are operated, a capacitor of at least another power conversion unit to be charged and connected.SOLUTION: The power conversion device comprises a plurality of power conversion units each formed from a converter, an inverter and a chopper. The power conversion device comprises: a first circuit breaker that is provided between a chopper circuit input terminal that is built in a first power conversion unit among the plurality of power conversion units, and a DC reactor that is connected to a DC power source; and a second circuit breaker for connecting a positive electrode terminal of another second power conversion unit that is different from the first power conversion unit, the DC power source and the DC reactor. When connecting the second power conversion unit in parallel while the first power conversion unit is operated, by closing the first circuit breaker and the second circuit breaker, the chopper circuit input terminal and the positive electrode terminal are connected via the reactor.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a power conversion device.

  In particular, a power conversion device is desired to have a small installation area because a UPS (Uninterruptable Power-supplement System, uninterruptible power supply) is laid in the vicinity of a city with a high land price for a data center. Similarly, there is a craving for products that keep running costs due to power converter efficiency and maintenance costs such as replacement of parts low. In addition, there is a demand for continuous operation during maintenance in a system (for example, a data center) in which a stop causes a large loss.

  In response to this problem, a system has been proposed in which N + 1 redundant operation is performed by a system in which the UPS main body is made N + 1 parallel to a system that requires N parallel power from the required power capacity. In a system with multiple UPS units in parallel, when at least one first UPS is in operation, the other UPS is turned off and disconnected from the power system in the other second UPS. Maintenance such as parts replacement in the second UPS can be performed in the operating state. On the other hand, by arranging N + 1 parallel UPS main units, the AC filter and the like are also multiplied by N + 1, which increases the ground contact area and the number of components.

  As a means for realizing redundant operation with a small number of parts, an N + 1 parallel configuration of an inverter unit, a converter unit, and a chopper unit in the UPS main body can be considered for a system that requires N parallel power from the required power capacity. However, when replacing or adding another unit while some units are operating, it is necessary to suppress inrush current from the power system / operating unit to the capacitor in the additional unit.

  In Patent Document 1, as a method of charging a capacitor including a plurality of power conversion units, for example, one charging circuit is used to charge one first inverter unit included in the power conversion unit, and the other A method has been proposed in which the smoothing capacitor of the inverter unit is charged via the load from the inverter circuit output of the initially charged inverter unit.

JP 2014-158340 A

  According to the method described in Patent Document 1, it is an invention in the initial charging of a plurality of inverter units, and none of the inverter units is charged before the start of charging. Any one of the charging circuits can handle charging of the multi-parallel unit, but in order to ensure redundancy in the charging circuit, it is necessary to make the charging circuits multi-parallel.

  Therefore, the present invention configures a capacitor charging circuit with a small number of parts, and can charge and connect a capacitor of at least one other power conversion unit while the inverter and converter of the at least one power conversion unit are operating. An object of the present invention is to provide a power conversion device that supports hot swapping.

  In order to solve the above-described problem, for example, a power conversion device including a plurality of power conversion units including a converter, an inverter, and a chopper, the chopper built into one first power conversion unit among the plurality of power conversion units. A first switch provided between a circuit input terminal and a DC reactor connected to a DC power supply; a positive terminal of a second power conversion unit different from the first power conversion unit; a DC power supply; and the DC A second switch for connecting between the reactors, and when the second power conversion unit is connected in parallel while the first power conversion unit is in operation, the first switch and the second switch The chopper circuit input terminal and the positive electrode terminal are connected via the reactor by closing the device.

  Capacitor charging circuit is configured with a small number of parts, and it supports hot swapping that enables charging and connection of capacitors of at least one other power conversion unit while the inverter and converter of at least one power conversion unit are operating. A power converter is provided.

It is a system diagram of an uninterruptible power supply. It is a figure which shows the main electric circuits which comprise a converter. It is a circuit diagram which shows the structure of an inverter circuit. It is a circuit diagram which shows the structure of a chopper circuit. The block diagram of UPS which connected two power conversion units which consist of a converter, an inverter, and a chopper in parallel is shown. The flowchart of initial charge is shown. It is a block diagram of the power converter device of a 2nd Example. The chopper part equivalent circuit of the 1st power conversion unit in a 2nd Example, and the chopper control signal of a high-order control circuit are shown. The chopper control voltage and the charging current with respect to the chopper control signal of the host control circuit are shown. It is a block diagram of the power converter device of a 3rd Example. The flowchart of the initial charge of the 3rd Example is shown. It is a block diagram of the power converter device of a 4th Example.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In this embodiment, a UPS (Uninterruptable Power-supplement System) will be described as a representative example.

  FIG. 1 is a system diagram of an uninterruptible power supply (hereinafter referred to as “UPS”) 100. Three-phase AC power input from the commercial AC power supply 106 is input to the converter 102 via the converter-side AC reactor 406. The converter 102 converts the three-phase AC power into DC power, converts the AC power again into AC power by the inverter 103, and supplies the AC power to the load 108 via the inverter-side AC filter 408. The electric power converted into direct current by the converter 102 is stored in the storage battery 107 by being stepped up or down to an optimum voltage by the chopper 104 and the DC reactor 407. The operations of the converter, inverter, and chopper are controlled by the host control circuit 105.

  When the commercial power source 106 fails for some reason, the power stored in the storage battery 107 is supplied to the inverter 103, converted into AC power, and supplied to the load 108, so that the load 108 can be supplied without interruption. it can.

  FIG. 2 is a diagram showing main electric circuits constituting converter 102. The converter 102 converts the three-phase AC power from the three-phase AC commercial power source 106 into DC power between the positive electrode and the negative electrode (between PN). The three-phase AC power 106 to be input is supplied to the AC terminals R, S, and T of the phase converters 201, 202, and 203 of the three-phase converter 102, and the switching element 21 and the rectifier of the upper arm provided in each phase. The element 23, the lower arm switching element 22 and the rectifying element 24 are rectified by controlling the switching timing by the converter control circuit 204. In this embodiment, an IGBT (Insulated Gate Bipolar Transistor) is used as the switching element and a diode is used as the rectifying element. However, the present invention is not limited to this, and other types of elements can be applied.

  FIG. 3 is a circuit diagram showing the configuration of the inverter circuit. The inverter control circuit 304 controls the switching timing of the DC voltage converted by the converter 102 in the switching element 21 and the rectifying element 23 of the upper arm and the switching element 22 and the rectifying element 24 of the lower arm provided for each phase. By doing so, it is converted into AC power and output to the AC terminals U, V, W of the phase converters 301, 302, 303.

  FIG. 4 is a circuit diagram showing the configuration of the chopper circuit. The step-up chopper 104 converts a low-voltage DC voltage generated by the storage battery 107 into a high-voltage DC voltage across the PN. While the lower arm switching element 22 is ON, energy is accumulated in the DC reactor 407 connected between the storage battery 107 and the AC terminal C. Next, when the switching element 22 of the lower arm is turned OFF, the rectifying element 23 of the upper arm is turned ON by the counter electromotive voltage generated by the reactor 407. As a result, the sum of the DC voltage of the storage battery 107 and the counter electromotive voltage of the reactor 407 appears at the output terminal of the boost chopper 104, and as a result, the voltage is boosted. Further, the step-up ratio can be arbitrarily set by controlling the switching timing by the chopper control circuit 405.

  From the above, the converter 102, the inverter 103, and the step-up chopper 104 mounted on the UPS 100 of the present embodiment are all the switching element 21 and the rectifying element 23 of the upper arm, the switching element 22 and the rectifying element 24 of the lower arm, The basic structure is a two-level half-bridge circuit 20 in which are connected in series, but it is also possible to apply an inverter, converter and booster circuit having a basic structure of three levels.

  FIG. 5 shows a configuration diagram of the UPS 100 in the present embodiment in which two power conversion units 200 including a converter 102, an inverter 103, and a chopper 104 are connected in parallel.

  Converter input terminals 501a and 501b of each power conversion unit 200a and 200b are connected to a common reactor 406 via switches SW_ac11 and SW_ac21, respectively. Similarly, the inverter output terminals 502a and 502b are connected to the common reactor 408 via the switches SW_ac12 and SW_ac22, respectively. The chopper input terminals 503a and 503b are connected to the DC reactor 407 via the switches SW_dc11 and SW_dc21. Moreover, each P pole terminal and each N pole terminal of the 1st power conversion unit 200a and the 2nd power conversion unit 200b are connected via switch SW_p12, SW_p22, SW_n11, SW_n21. The P pole terminal of each power conversion unit is connected between the DC reactor 407 and the DC input switch SW_dc via the switches SW_p11 and SW_p21. Capacitors 25a and 25b can be charged by closing the switches SW_p11 and SW_p21. That is, when the power conversion unit 200a is in operation, the chopper input terminal 503a of the power conversion unit 200a and the P pole terminal of the power conversion unit 200b are connected via the switch SW_dc11, the reactor 407, and the switch SW_p21. Thus, the charging current of the capacitor 25b can be supplied from the power conversion unit 200a to the power conversion unit 200b.

  The upper control circuit 109 that controls each power conversion unit includes a mechanism that monitors the voltage between the P and N poles of each power conversion unit and controls the chopper operation.

  In this embodiment, polar capacitors such as electrolytic capacitors are assumed as the capacitors 25a and 25b. However, a nonpolar capacitor such as a film capacitor can be charged with the same configuration.

  FIG. 6 shows a flowchart of initial charging. Hereinafter, an initial charging operation when the second power conversion unit 200b is added under the condition that the inverter / converter of the first power conversion unit 200a is operating will be described.

  First, when the first power conversion unit 200a of FIG. 5 is driven, the switches SW_ac11, SW_ac12, SW_dc11, SW_p12, SW_n11, SW_dc connecting the input / output systems are closed, and the first power conversion unit The switch SW_p11 in the charging path of the capacitor 25a is open.

  The switches SW_ac21, SW_ac22, SW_dc21, SW_p22, SW_n21, and SW_p21 connected to the second power conversion unit 200b that is the additional unit are in an open state.

  The charging operation of the capacitor 25b in the second power conversion unit will be described using a flowchart.

  First, SW_n21 is closed, and the N potential of the first power conversion unit and the N potential of the second power conversion unit are set to the same potential. Further, with SW_dc opened and the DC reactor 407 and the storage battery 107 disconnected, SW_p21 is closed, and the P pole terminal of the second power conversion unit and the chopper terminal 503a of the first power conversion unit are connected to the DC reactor. Connection is made via 407 (step 601). Note that either the timing for closing SW_n21 or the timing for opening SW_dc may be earlier, and SW_p21 is closed after these operations. Further, the upper arm switching element 21 of the chopper circuit of the first power conversion unit is controlled to be off as an initial state.

  The chopper circuit of the first power conversion unit is operated at a specific duty ratio. At this time, a charging current flows through the capacitor 25b of the second power conversion unit via the chopper terminal 503a, the switch SW_dc11, the DC reactor 407, and the switch SW_p21 of the first power conversion unit (step 602). . The host control circuit 109 monitors the voltage between the P and N poles of the second power conversion unit, and when the predetermined set value is reached (Yes in step 603), the chopper circuit of the first power conversion unit is turned off. (Step 604), the charging current is cut off. In step 604, specifically, the switch SW_p21 is opened, the charging current path from the chopper of the first power conversion unit to the second power conversion unit is cut off, and the switches SW_ac21, SW_ac22, SW_p22, SW_dc21 are disconnected. And the converter input terminals 501a and 501b, the inverter output terminals 502a and 502b, the chopper input terminals 503a and 503b, and the P pole N pole terminal in the first power conversion unit and the second power conversion unit, respectively. Connecting. Further, the switch SW_dc is closed, the DC reactor 407 and the storage battery 107 are connected, and the second power conversion unit starts the inverter / converter operation synchronized with the first power conversion unit.

  According to the present embodiment, even when the first power conversion unit is operating in the inverter / converter operation, the second power conversion unit can be added (initial charge). That is, since the charging current of the second power conversion unit passes through the chopper circuit of the first power conversion unit, the charging current can be controlled by chopper control. In addition, by using the chopper built in each power conversion unit as a charging circuit and sharing the DC reactor in each unit (having a connection part connected from the reactor to the chopper of each unit), few additions Supports hot swapping with parts. Further, charging from the second power conversion unit to the first power conversion unit is also possible, and the redundancy of the charging circuit can be ensured similarly to the multi-parallel unit.

  On the other hand, for example, when the second power conversion unit needs to be removed during maintenance, all the SW elements of the inverter, converter, and chopper of the second power conversion unit are controlled to be turned off, and the second power conversion unit is removed from the power system and the storage battery. With the current flowing through the power conversion unit cut off, the switches SW_ac21, SW_dc21, SW_p21, SW_ac22, SW_p22, and SW_n21 are opened, so that the power system and the first power conversion unit can be switched to the second power conversion unit Can be separated.

  FIG. 7 is a configuration diagram of the power conversion device according to the second embodiment.

  In the following, an operation as a unit in which the inverter and converter of the first power conversion unit are in operation and the second power conversion unit is added and initially charged will be described.

  The host control circuit 109 is different from the first embodiment in that the output current of the AC filter reactor 408 is monitored in addition to the P-pole N-pole voltage of the second power conversion unit.

  The upper control circuit 109 switches the chopper continuity of the first power conversion unit that controls the charging current of the second power conversion unit according to the output current signal.

  FIG. 8 shows a chopper part equivalent circuit of the first power conversion unit.

  FIG. 9 shows the chopper control voltage and the charging current for the chopper control signal S1 of the host control circuit 109. The horizontal axis represents time, and the vertical axis represents chopper control voltage and charging current.

  As shown in FIG. 9, the host control circuit switches the pulse signal duty ratio of the chopper control signal S <b> 1 according to the output current of the AC filter reactor 408.

  When the output current is small, since the loss of the inverter and converter of the first power conversion unit is small, the S1a signal having a large pulse signal duty ratio increment is selected as the chopper control signal S1. Thus, when the change (increment) of the pulse width is large, the charging current can be increased.

  On the other hand, when the output current is large, since the loss of the inverter and converter of the first power conversion unit is large, the S1b signal having a small increment of the pulse signal duty ratio is selected as the chopper control signal S1. If the charging current is increased when the output current of the inverter / converter is large, the converter will generate more heat, leading to malfunctions. By limiting the charging current while monitoring the output current in this way, Excessive heat generation / failure can be avoided.

  In addition, with respect to the chopper control signal S1b, in the chopper control signal S1a, the charging current becomes smaller and the charging time becomes longer.

  According to the present embodiment, in the first power conversion unit in which the inverter and the converter are operating, it is possible to reduce the influence of an increase in loss due to an increase in charging current to the second power conversion unit and an increase in heat generation. That is, when the inverter and converter of the first power conversion unit are operating at a high load, that is, when the loss and heat generation of the inverter and converter are large, the charging current is limited by applying the chopper control signal S1b. And the temperature rise of an inverter and a converter can be suppressed.

  In the present embodiment, the operation state of the inverter and converter of the power conversion unit that supplies the charging current is determined by the output current of the AC filter reactor 408, and the chopper control signal S1 is controlled. On the other hand, the same control is possible when the AC reactor 406 input current, the converter input current, the inverter output current, or the temperature information of the inverter and converter unit is used as information for determining the operation state of the inverter and the converter. is there.

  FIG. 10 is a configuration diagram of the power conversion device according to the third embodiment.

  The difference from the first and second embodiments is the configuration positions of the switch SW_dc1 and the switch SW_dc2. The chopper input terminals 503a and 503b are connected to each other via the switch SW_dc1. Further, the chopper input terminals 503a and 503b are connected to each other via the DC reactor 407 and the switch SW_dc2. By comprising in this way, the number of switches can be reduced compared with the structure of the power converter device of Example 1 and Example 2. FIG.

  FIG. 11 shows a flowchart of initial charging in the present embodiment. Hereinafter, an initial charging operation when the second power conversion unit 200b is added under the condition that the inverter / converter of the first power conversion unit 200a in FIG. 10 is operating will be described.

  When the first power conversion unit 200a is driven, the switches SW_ac11, SW_ac12, SW_p12, SW_n11, and SW_dc connecting the input / output systems are closed, and the chopper input terminal 503a of the first power conversion unit; The switches SW_dc1 and SW_dc2 that connect the chopper input terminal 503b of the second power conversion unit are both open. Further, the switches SW_ac21, SW_ac22, SW_dc1, SW_p22, and SW_n21 connected to the second power conversion unit 200b that is the additional unit are in an open state.

  As charging operation of the capacitor 25b in the second power conversion unit, SW_n21 is closed, and the N potential of the first power conversion unit and the N potential of the second power conversion unit are set to the same potential. Further, with SW_dc open and the DC reactor 407 and storage battery 107 disconnected, SW_dc2 is closed, and the chopper terminal 503b of the second power conversion unit and the chopper terminal 503a of the first power conversion unit are connected to the DC reactor. Connection is made via 407 (step 1001). At this time, the timing of opening SW_dc and SW_dc1 and the timing of closing SW_n21 are in no particular order, but SW_dc2 is controlled to close after the operation of these switches. Note that the upper arm switching element 21 of the chopper circuit of the first power conversion unit and the upper arm switching element 21 and the lower arm switching element 22 of the chopper circuit of the second power conversion unit are all controlled to be off as an initial state. Has been.

  Next, the chopper circuit of the first power conversion unit is operated at a specific duty ratio (step 1002). At this time, the capacitor 25b of the second power conversion unit includes the chopper terminal 503a of the first power conversion unit, the DC reactor 407, the switch SW_dc2, the chopper terminal 503b of the second power conversion unit, and the second power. A charging current flows through the upper arm rectifying element 23 of the chopper circuit of the conversion unit. The host control circuit 109 monitors the voltage between the P and N poles of the second power conversion unit, and when the predetermined set value is reached (Yes in step 1003), the chopper circuit of the first power conversion unit is turned off. , Cut off the charging current. On the other hand, if the predetermined value is not reached, the same determination is repeated (No in step 1003).

  Next, the switch SW_dc2 is opened, the charging current path from the chopper of the first power conversion unit to the second power conversion unit is interrupted, the switches SW_ac21, SW_ac22, SW_p22, SW_dc1 are closed, Converter input terminals 503a and 503b, inverter output terminals 502a and 502b, chopper input terminals 503a and 503b, and P-pole N-pole terminals in the power conversion unit and the second power conversion unit are connected to each other. Further, the switch SW_dc is closed, the DC reactor 407 and the storage battery 107 are connected, and the second power conversion unit starts the inverter / converter operation synchronized with the first power conversion unit.

  According to the present embodiment, even when the first power conversion unit is operating in the inverter / converter operation, the second power conversion unit can be added (initial charge). Since the charging current of the second power conversion unit passes through the chopper circuit of the first power conversion unit, the charging current can be controlled by chopper control. Further, by using a chopper built in each power conversion unit as a charging circuit and sharing a DC reactor in each unit, hot swapping is supported with a small number of additional parts.

  During maintenance, for example, when it is necessary to remove the second power conversion unit, all the SW elements of the inverter, converter, and chopper of the second power conversion unit are controlled to be turned off, and the second power is supplied from the power system and the storage battery. The second power conversion unit is disconnected from the power system and the first power conversion unit by opening the switches SW_ac21, SW_dc1, SW_ac22, SW_p22, SW_n21 while the current flowing through the conversion unit is interrupted. Is possible.

  FIG. 12 is a configuration diagram of the power conversion device according to the fourth embodiment. In this embodiment, the UPS 100 has a configuration in which three power conversion units 200 are connected in parallel.

  The chopper input terminal 503a of the first power conversion unit 200a and the chopper input terminal 503b of the second power conversion unit are connected to the switch SW_dc1. Furthermore, the chopper input terminal 503a of the first power conversion unit 200a and the chopper input terminal 503b of the second power conversion unit are connected to the DC reactor 407 via the switch SW_dc2. On the other hand, the chopper input terminal 503b of the second power conversion unit and the chopper input terminal 503c of the third power conversion unit are connected via a switch SW_dc3.

  When charging the third power conversion unit 200c, the charging current is supplied from the chopper in the first power conversion unit via the DC reactor 407, the switch SW_dc2, and the switch SW_dc3. To the chopper input terminal 503c. It is also possible to supply a charging current from the third power conversion unit to the first power conversion unit through the same current path.

  According to this Embodiment, the switch between the chopper input terminals of the 2nd power conversion unit and the 3rd power conversion unit can be constituted by one, and the number of parts can be reduced.

  Although the embodiment described above refers to UPS, it can be applied to different power converters (for example, PCS) and is not limited to the configuration of the above embodiment. Moreover, although the switch was described as an example, other means may be used as long as the electrical connection state is turned on and off.

20... 2 level half bridge circuit 21, 22... Switching element (IGBT)
23, 24 ... Rectifier element (diode)
25 ... Capacitor elements 27, 28 ... Fuse element 100 ... Power converter (UPS)
DESCRIPTION OF SYMBOLS 102 ... Converter 103 ... Inverter 104 ... Chopper 105, 109 ... High-order control part 106 ... Commercial alternating current power supply 107 ... Storage battery 108 ... Load 200 ... Power conversion unit 201 ... Converter R phase power conversion unit 202 ... Converter S phase power conversion unit 203 ... Converter T-phase power conversion unit 204 ... converter control circuit 301 ... inverter U-phase power conversion unit 302 ... inverter V-phase power conversion unit 303 ... inverter W-phase power conversion unit 304 ... inverter control circuit 401 ... chopper power conversion unit 405 ... chopper control Circuits 406, 407, 408 ... reactor 501 ... converter input terminal 502 ... inverter output terminal 503 ... chopper input terminal

Claims (11)

A power conversion device having a plurality of power conversion units including a converter, an inverter, and a chopper,
A first switch provided between a chopper circuit input terminal built in one first power conversion unit among the plurality of power conversion units and a DC reactor connected to a DC power supply;
A second switch for connecting a positive terminal of another second power conversion unit different from the first power conversion unit and the DC power source and the DC reactor;
When the second power conversion unit is connected in parallel while the first power conversion unit is in operation, the chopper circuit input terminal and the positive terminal are closed by closing the first switch and the second switch. Is a power conversion device connected via the reactor. The power conversion device according to claim 1,
By closing the first switch and the second switch, from the chopper circuit built in the first power conversion unit, via the reactor, the positive terminal of the second power conversion unit A power conversion device in which a current flows through the capacitor and a capacitor provided in the second power conversion unit is charged. The power conversion device according to claim 1,
When charging the second power conversion unit, the converter circuit input terminal built in the first power conversion unit and the converter circuit input terminal built in the second power conversion unit are electrically Insulated and
The inverter circuit output terminal incorporated in the first power conversion unit and the inverter circuit output terminal incorporated in the second power conversion unit are electrically insulated from each other. . The power conversion device according to claim 1,
The converter circuit input terminal built in the first power conversion unit and the converter circuit input terminal built in the second power conversion unit are connected via a switch,
The inverter circuit output terminal built in the first power conversion unit and the inverter circuit output terminal built in the second power conversion unit are connected via a switch. apparatus. The power conversion device according to claim 2,
The power converter is
The control circuit included in the first power conversion unit, the control circuit for supplying a control signal to a chopper circuit,
Voltage information between the positive and negative electrodes of the second power conversion unit is input to the control circuit, and the control circuit performs chopper circuit of the first power conversion unit until the voltage between the positive and negative electrodes reaches a rated voltage. The power conversion device that controls the charging current to flow through the positive terminal of the second power conversion unit. The power conversion device according to claim 5,
Output current information of the inverter circuit included in the first power conversion unit is input to the control circuit, and a chopper built in the first power conversion unit based on the magnitude of the inverter circuit output current A power conversion device characterized by changing a conductivity of a circuit. The power conversion device according to claim 6, wherein
The power converter which makes the increase rate of the said continuity rate small, so that the said inverter circuit output current is large. A power conversion device having a plurality of power conversion units including a converter, an inverter, and a chopper,
A chopper circuit input terminal built in one first power conversion unit among the plurality of power conversion units, and a chopper circuit built in another second power conversion unit different from the first power conversion unit The input terminal is connected via a switch,
When the second power conversion unit is connected in parallel while the first power conversion unit is in operation, the chopper circuit input terminal and the positive terminal are connected via the reactor by closing the switch. Power converter. The power conversion device according to claim 8, wherein
A chopper circuit input terminal built in the second power conversion unit, and a third power conversion unit different from the first power conversion device and the second power conversion device among the power conversion devices. The chopper circuit input terminal is a power converter connected via one switch The power conversion device according to claim 8, wherein
The power converter device further provided with the 2nd switch for connecting between the positive electrode terminal of a 2nd power conversion unit, and the said DC power supply and the said DC reactor. The power conversion device according to claim 8, wherein
The chopper circuit includes a rectifier element between a chopper circuit input terminal and a positive terminal,
The chopper circuit input terminal of the second power conversion unit is connected to the positive terminal of the second power conversion unit through the rectifying element.

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