JP2012115018A - Power controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power controller, which includes: an inverter; a step-up converter with a reactor, a switching element and a rectifier; and a first and a second smoothing capacitors, the power controller capable of individually determining degradation in the reactor of the step-up converter and the first and the second capacitors.SOLUTION: A power controller 20 includes: a second relay 42 disposed between a first relay 41 and a first capacitor 31, and a reactor L; a third relay 43 disposed between the reactor L of the step-up converter 23 and a diode D1; and a resistance element 33 connected in serial to the reactor L and in parallel to a transistor Tr2.

Description

  The present invention relates to a power control device including an inverter, a boost converter having a reactor, a switching element, and a rectifying element, and smoothing capacitors on an input side and an output side.

  Conventionally, this type of power control apparatus has an inverter circuit for driving an electric motor capable of inputting / outputting power, and a reactor connected to the positive side of a DC power supply via a system main relay and a voltage of the DC power supply. A booster circuit for boosting and supplying the voltage to the inverter circuit, a first capacitor for smoothing the voltage on the DC power supply side of the booster circuit, and a second capacitor for smoothing the voltage on the inverter circuit side of the booster circuit, When an overcurrent flows in the circuit, the system main relay is turned off and the electric power stored in the first and second capacitors is controlled by controlling the inverter circuit so that the electric motor consumes power without outputting torque. What is made to discharge is proposed (for example, refer to patent documents 1). In this power control apparatus, when the first and second capacitors are discharged due to the overcurrent flowing through the inverter circuit, the discharge duration times of the first and second capacitors are measured, and the discharge duration time is determined from a predetermined threshold value. If it is shorter, it is determined that at least one of the first and second capacitors is abnormal (capacitance is lower than that in the normal state). As this type of power control device, a power transistor unit connected to the battery via a switch and converting DC power from the battery into AC power, and an electrolytic capacitor connected in parallel to the power transistor unit, It is also proposed to measure the charging time from when the switch is turned on until the electrolytic capacitor is charged and reach a predetermined voltage, and to determine that the electrolytic capacitor has deteriorated when the charging time is shorter than the reference time (For example, refer to Patent Document 2).

JP 2009-189214 A JP-A-5-215800

  However, the power control device described in Patent Document 1 cannot determine which of the first and second capacitors has deteriorated. In addition, in the power control device described in Patent Document 1, there is a possibility that the reactor of the booster circuit may be deteriorated in addition to the first and second capacitors. However, Patent Document 1 describes the deterioration of the reactor of the booster circuit. There is no description about the judgment.

  The present invention relates to a power control apparatus including an inverter, a boost converter having a reactor, a switching element, and a rectifying element, and first and second capacitors for smoothing. The main purpose is to make it possible to determine deterioration individually.

  The power control apparatus of the present invention employs the following means in order to achieve the main object described above.

The power control device of the present invention includes an inverter that converts DC power from a DC power source into AC power, and stores energy in a reactor when the switching element is turned on, and a rectifier element when the switching element is turned off. A boost converter that superimposes and outputs the energy accumulated in the reactor to a voltage from the DC power supply, a first switch disposed between the DC power supply and the reactor of the boost converter, A first capacitor connected in parallel with the boost converter to the DC power source on the boost converter side of the first switch, and a second capacitor connected in parallel with the inverter with respect to the boost converter Current acquisition means for acquiring a current flowing through the DC power source, and acquiring a voltage across the terminals of the first capacitor. A power control device comprising a first voltage acquiring means, and a second voltage acquiring means for acquiring a terminal voltage of said second capacitor,
A second switch disposed between the first switch and the first capacitor and the reactor;
A third switch disposed between the reactor of the boost converter and the rectifying element;
And a resistor connected in series to the reactor and connected in parallel to the switching element.

  In the power control apparatus of the present invention, if the second and third switches are turned off and only the first switch is turned on while the inverter is shut down, the power from the DC power supply is supplied only to the first capacitor. The first capacitor is charged, and the voltage between the terminals of the first capacitor converges to a predetermined voltage (voltage between terminals of the DC power supply) as the charging proceeds. Therefore, when the time from when only the first switch is turned on until the voltage between the terminals of the first capacitor acquired by the first voltage acquisition unit becomes a predetermined voltage is shorter than a predetermined threshold, for example, It can be determined that the first capacitor has deteriorated and its capacity has decreased. Also, if the third switch is turned off and the first and second switches are turned on while the inverter is shut down, the current from the DC power source flows through the reactor and the resistor of the boost converter, and the current is It gradually increases according to the resistance characteristics and eventually converges to a constant value. Therefore, when the time from when the first and second switches are turned on until the current flowing through the DC power source acquired by the current acquisition unit reaches a certain value is shorter than a predetermined threshold, the reactor deteriorates. Thus, it can be determined that the inductance is reduced. Furthermore, if all of the first, second, and third switches are turned on while the inverter is shut down, the power from the DC power source is supplied to the second capacitor via the reactor, the third switch, and the rectifier of the boost converter. And the second capacitor is charged, and the voltage between the terminals of the second capacitor converges to a predetermined voltage (voltage between terminals of the DC power supply) as the charging proceeds. Accordingly, the time from when all of the first, second, and third switches are turned on until the voltage between the terminals of the second capacitor acquired by the second voltage acquisition means becomes a predetermined voltage is more than a predetermined threshold value. If it is too short, it can be determined that the second capacitor has deteriorated and its capacity has decreased. As a result, in the power control apparatus of the present invention, it is possible to individually determine the deterioration of the reactor of the boost converter and the first and second capacitors. In addition, by connecting a resistor in series with the reactor and in parallel with the switching element, it becomes possible to use the resistor as a discharge resistor for discharging the charge accumulated in the first capacitor, thereby suppressing an increase in the number of components. can do.

It is a schematic block diagram of the electric vehicle 10 carrying the power control unit 20 which concerns on one Example of this invention. FIG. 6 is an explanatory diagram showing an example of temporal changes in terminal voltages VL and VH and battery current Ib of first and second capacitors 31 and 32 after start switch 51 is turned on in electric vehicle 10.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a schematic configuration diagram of an electric vehicle 10 equipped with a power control unit 20 as a power control apparatus according to an embodiment of the present invention. As shown in the figure, an electric vehicle 10 according to an embodiment includes, for example, a motor 11 that is configured as a synchronous generator motor and has a rotor connected to drive wheels 18a and 18b via a differential gear 16, and the motor 11 and the electric power A power control unit (power control device) that controls power exchanged between the motor 11 and the battery 12 and a battery (DC power supply) 12 that can be exchanged, for example, a lithium ion secondary battery or a nickel hydride secondary battery. 20 and a power control unit 20 and an electronic control unit 40 for controlling the entire vehicle. The power control unit 20 is interposed between the motor 11 and the battery 12 and is connected to the inverter 22 that drives the motor 11, and the battery 12 via the first relay (first switch) 41 and the power line 38. And the boost converter 23 capable of boosting the electric power from the battery 12 and supplying the boosted power to the inverter 22 and the boost converter 23 in parallel to the battery 12 on the boost converter 23 side of the first relay 41. A first capacitor 31 and a second capacitor 32 connected in parallel to the inverter 22 with respect to the boost converter 23 are provided.

  The first relay 41 is connected to the positive terminal 41 a of the battery 12 and the positive bus 38 a of the power line 38, and is connected to the negative terminal 41 b of the battery 12 and the negative bus 38 b of the power line 38. The relay 41b includes an avoidance relay 41c and a resistance element 41d connected in parallel to the positive relay 41a in order to avoid an inrush current when the positive relay 41a is turned on. The inverter 22 also converts the DC power from the battery 12 into AC power by switching a plurality of switching elements, and supplies the phase current for forming a rotating magnetic field to the three-phase coil of the motor 11 to rotate the motor 11. The inverter is configured as a known inverter that can be driven.

  Boost converter 23 includes a reactor L having one end connected to the positive terminal of battery 12 via first relay 41, and two transistors (switching elements) Tr1 and Tr2 that are, for example, insulated gate bipolar transistors (IGBT). And diodes (rectifier elements) D1 and D2. The emitter of the transistor Tr1 is connected to the other end of the reactor L, and the collector of the transistor Tr1 is connected to the inverter 22 side. The anode of the diode D1 is connected to the other end of the reactor L, and the cathode of the diode D1 is connected to the inverter 22 side. The emitter of the transistor Tr2 is connected to the negative bus 38b, and the collector of the transistor Tr2 is connected to the other end of the reactor L. The anode of the diode D2 is connected to the negative bus 38b, and the cathode of the diode D1 is connected to the other end of the reactor L. Therefore, the other end of the reactor L is connected to the midpoint of the transistors Tr1 and Tr2, the diode D1 is connected in parallel to the transistor Tr1 in the reverse direction, and the diode D2 is connected in parallel to the transistor Tr2 in the reverse direction.

  Of the two transistors Tr1 and Tr2, the transistor (lower arm) Tr2 located on the lower side of the figure and the diode D1 located on the upper side of the two diodes D1 and D2 are connected to the reactor 12 together with the reactor L. A boost chopper circuit that boosts the voltage is configured. That is, when the transistor Tr2 is turned on, energy is accumulated in the reactor L. When the transistor Tr2 is subsequently turned off, the voltage boosted by superimposing the energy accumulated in the reactor L on the voltage from the battery 12 is diode-converted. It is output via D1. The transistor (upper arm) Tr1 located on the upper side of the two transistors Tr1 and Tr2 and the diode D2 located on the lower side of the two diodes D1 and D2 are connected to the motor 11 together with the reactor L. A step-down chopper circuit for stepping down the voltage from is configured. Therefore, if the transistors Tr1 and Tr2 are on / off controlled, the voltage from the battery 12 is boosted by the boost converter 23 and supplied to the inverter 22, or the voltage from the motor 11 is stepped down and supplied to the battery 12. It becomes possible.

  Furthermore, in the power control unit 20 of the embodiment, the first relay 41 and the first capacitor 31 and the reactor L of the boost converter 23, that is, the positive relay 41a and the avoidance relay 41c constituting the first relay 41, A second relay (second switch) 42 is disposed between the boost converter 23 and the reactor L so as to be positioned closer to the reactor L than the first capacitor 31 (a connection point with the positive bus). Turning on the second relay 42 electrically connects the battery 12 and the reactor L via the first relay 41 and turning off the second relay 42 releases the electrical connection between the battery 12 and the reactor L. can do. Further, a third relay (third switch) 43 is disposed between the reactor L of the boost converter 23 and the anode of the diode D1. Turning on the third relay 43 electrically connects the reactor L and the anode of the diode D1, and turning off the third relay 43 releases the electrical connection between the reactor L and the anode of the diode D1. it can. In addition, the power control unit 20 according to the embodiment includes a resistance element 33 connected in series to the reactor L and connected in parallel to the transistor Tr2. That is, one end of the resistance element 33 is connected between the reactor L and the anode of the diode D1, and the other end of the resistance element 33 is connected to the negative electrode bus 38b. The resistance element 33 is also used as a discharge resistor for discharging the charge accumulated in the first capacitor 31.

  The first capacitor 31 smoothes the voltage between the boost converter 23 and the battery 12, and a voltage sensor that detects the voltage VL between the terminals of the first capacitor 31 between the terminals of the first capacitor 31. 34 is arranged. The second capacitor 32 smoothes the voltage between the boost converter 23 and the inverter 22, and detects the inter-terminal voltage VH of the second capacitor 32 between the terminals of the second capacitor 32. A voltage sensor 35 is arranged. Further, the power control unit 20 includes a resistance element 36 connected in parallel to the second capacitor 32 between the boost converter 23 and the inverter 22. The resistance element 36 is used as a discharge resistor for discharging the charge accumulated in the second capacitor 32. A current sensor 37 that detects a battery current Ib that is a current flowing through the battery 12 is installed on the positive bus 38a.

  The electronic control unit 40 includes a start instruction signal from the start switch 51, an accelerator opening from the accelerator pedal position sensor 55 that detects the amount of depression of the accelerator pedal 54, a vehicle speed from the vehicle speed sensor 58, and a battery current from the current sensor 37. Ib, the voltage VL between the terminals of the first capacitor 31 from the voltage sensor 34, the voltage VH between the terminals of the second capacitor 32 from the voltage sensor 35, and the like are input via the input port. From the electronic control unit 40, a switching control signal to the inverter 22, a switching control signal to the boost converter 23, an on / off signal to the first to third relays 41 to 43, and the like are output via an output port.

  When the electric vehicle 10 according to the embodiment travels, the electronic control unit 40 uses the accelerator pedal position sensor 55 that detects the amount of depression of the accelerator pedal 54 and the vehicle speed from the vehicle speed sensor 58 to travel. The required torque required for the motor 11 is set. Then, based on the set required torque and the rotation speed of the motor 11, a target voltage to be applied to the inverter 22 is set so as to increase as the required torque and the rotation speed of the motor 11 increase, and the first to third relays 41 are set. The transistors Tr1 and Tr2 are turned on / off using a predetermined duty ratio so that the inter-terminal voltage VH becomes the target voltage in a state where all of .about.43 are turned on, and torque corresponding to the required torque is output from the motor 11. The inverter 22 is controlled to be switched.

  Next, in the electric vehicle 10 of the embodiment, a procedure for determining the presence or absence of deterioration of the reactors L of the first capacitors 31 and 32 and the boost converter 23 will be described. In the embodiment, when the start switch 51 is turned on by the driver and electric power is started to be supplied from the battery 12 to the motor 11 via the boost converter 23 and the inverter 22, the electronic control unit 40 performs the first to first steps according to the following procedure. The three relays 41 to 43 are controlled to be turned on / off, and whether or not the first capacitors 31 and 32 and the reactor L of the boost converter 23 are deteriorated is determined. FIG. 2 shows the on / off states of the first to third relays 41 to 43 after the start switch 51 is turned on in the electric vehicle 10, the voltage VL, VH between the terminals of the first and second capacitors 31, 32, and the battery current Ib. An example of the time change of is shown. Note that the inverter 22 is shut down from the start to the completion of the deterioration determination described below.

  When the start switch 51 is turned on by the driver, the electronic control unit 40 turns on the negative relay 41b and the avoidance relay 41c of the first relay 41 while turning off the second and third relays 42 and 43 ( Hereinafter, turning on the negative side relay 41b and the avoidance relay 41c is referred to as “turning on the first relay 41”), and the current is passed to the first capacitor 31 via the resistance element 41d. In order to suppress the inrush current from flowing, the positive relay 41a is turned off (time t1 in FIG. 2). As a result, the power from the battery 12 is supplied only to the first capacitor 31 and the first capacitor 31 is charged. As shown in FIG. 2, the inter-terminal voltage VL of the first capacitor 31 is changed to the battery as charging progresses. 12 converges to the inter-terminal voltage VB (time t2 in FIG. 2). The electronic control unit 40 measures an elapsed time Δt1 from when the first relay 41 is turned on until the terminal voltage VL of the first capacitor 31 converges to the terminal voltage VB of the battery 12, and the measured elapsed time Δt1. The presence or absence of deterioration of the first capacitor 31 is determined by comparing with a predetermined threshold value tref1. Here, the threshold value tref1 is an experiment based on the capacity of the first capacitor 31 as the time from the start of applying the voltage VB to the first capacitor 31 until the charging is completed in a state where the first capacitor 31 is not deteriorated.・ Predetermined by analysis. Therefore, for example, when the elapsed time Δt1 is shorter than the threshold value tref1 by a predetermined time or more, it is possible to determine that the first capacitor 31 is deteriorated and the capacity is reduced. For example, the elapsed time Δt1 is equal to the threshold value tref1. If it falls within the allowable range at the center, it can be determined that the first capacitor 31 has not deteriorated. The current (battery current Ib) flowing from the battery 12 to the first capacitor 31 becomes the maximum immediately after the first relay 41 is turned on according to the characteristics of the first capacitor 31 and the resistance element 41d, and the charging of the first capacitor 31 is performed. As it progresses, it gradually decreases and becomes almost zero when the charging of the first capacitor 31 is completed.

  When it is determined whether or not the first capacitor 31 has deteriorated as described above, the electronic control unit 40 turns on the first relay 41 and turns on the second relay 42 while turning off the third relay 43 (FIG. 2). T3). Thus, current flows from battery 12 to reactor L of boost converter 23 and resistance element 33 connected in series therewith, and battery current Ib gradually increases according to the characteristics of reactor L and resistance element 33 and eventually reaches a constant value. (Time t4 in FIG. 2). The electronic control unit 40 measures the elapsed time Δt2 from when the second relay 42 is turned on until the battery current Ib converges to a constant value, and compares the measured elapsed time Δt2 with a predetermined threshold value tref2. Is used to determine whether the reactor L has deteriorated. Here, the threshold value tref2 is such that the current (battery current Ib) flowing through the reactor L and the resistance element 33 after the voltage VB starts to be applied to the reactor L and the resistance element 33 in a state where the reactor L has not deteriorated is constant. The time until convergence is determined in advance by experiments and analysis based on the inductance of the reactor L and the like. Therefore, for example, when the elapsed time Δt2 is shorter than the threshold value tref2 by a predetermined time or more, it is possible to determine that the reactor L has deteriorated and the inductance has decreased. For example, the elapsed time Δt2 has the threshold value tref2 as the center. If it falls within the allowable range, it can be determined that the reactor L has not deteriorated.

  Subsequently, the electronic control unit 40 turns on the third relay 43 with the first relay 41 and the second relay 42 turned on (time t5 in FIG. 2). As a result, power from the battery 12 is supplied to the second capacitor 32 via the reactor L of the boost converter 23, the third relay 43, and the diode D1, and the second capacitor 32 is charged. The voltage VH between the terminals of the two capacitors 32 converges to the voltage VB between the terminals of the battery 12 (time t6 in FIG. 2). The electronic control unit 40 measures an elapsed time Δt3 from when the third relay 43 is turned on until the inter-terminal voltage VH of the second capacitor 32 converges to the inter-terminal voltage VB of the battery 12, and the measured elapsed time Δt3 The presence or absence of deterioration of the second capacitor 32 is determined by comparing with a predetermined threshold value tref1. Here, the threshold value tref3 is an experiment based on the capacity of the second capacitor 32 as the time from the start of applying the voltage VB to the second capacitor 32 until the charging is completed in a state where the second capacitor 32 is not deteriorated.・ Predetermined by analysis. Therefore, for example, when the elapsed time Δt3 is shorter than the threshold value tref3 by a predetermined time or more, it is possible to determine that the second capacitor 32 is deteriorated and the capacity is reduced. If it falls within the allowable range at the center, it can be determined that the second capacitor 32 has not deteriorated.

  As described above, in the power control unit 20 of the embodiment, the second and third relays 42 and 43 are turned off while the inverter 22 is shut down, and the first relay 41, that is, the negative side relay 41b and the avoidance relay 41c. Is turned on, the power from the battery 12 is supplied only to the first capacitor 31 and the first capacitor 31 is charged. As the charging proceeds, the voltage VL between the terminals of the first capacitor 31 becomes a predetermined voltage (battery 12 To the terminal voltage VB). Accordingly, the elapsed time Δt1 from when only the first relay 41 is turned on until the voltage VL between the terminals of the first capacitor 31 obtained by the voltage sensor 34 becomes the voltage VB between the terminals of the battery 12 is, for example, a predetermined threshold value. If it is shorter than tref1 by a predetermined time or more, it can be determined that the first capacitor 31 has deteriorated and its capacity has decreased. Further, when the third relay 43 is turned off and the first and second relays 41 and 42 are turned on while the inverter 22 is shut down, the current from the battery 12 flows through the reactor L and the resistance element 33 of the boost converter 23. The current gradually increases according to the characteristics of the reactor L and the resistance element 33 and eventually converges to a constant value. Therefore, the elapsed time Δt2 from when the first and second relays 41 and 42 are turned on until the battery current Ib acquired by the current sensor 37 reaches a certain value is shorter than a predetermined threshold value tref2 by a predetermined time or more, for example. In this case, it can be determined that the reactor L is deteriorated and the inductance is reduced. Further, if all of the first relay 41, the second relay 42, and the third relay 43 are turned on while the inverter 22 is shut down, the power from the battery 12 is supplied to the reactor L, the diode of the third relay 43, and the boost converter 23. (Rectifier element) The second capacitor 32 is supplied to the second capacitor 32 via D1, and the second capacitor 32 is charged. As the charging progresses, the inter-terminal voltage VH of the second capacitor 32 becomes a predetermined voltage (between the terminals of the battery 12). Converges to voltage VB). Therefore, until all of the first relay 41, the second relay 42, and the third relay 43 are turned on until the terminal voltage VH of the second capacitor 32 acquired by the voltage sensor 35 becomes the terminal voltage VB of the battery 12. When the elapsed time Δt3 is shorter than a predetermined threshold value tref3 by a predetermined time or more, for example, it can be determined that the second capacitor 32 has deteriorated and its capacity has decreased. As a result, in the electric vehicle 10 equipped with the power control unit 20 of the embodiment, it is possible to individually determine the deterioration of the reactor L of the boost converter 23 and the first and second capacitors 31 and 32.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the inverter 22 that converts the DC power from the battery 12 into the AC power corresponds to an “inverter”. When the transistor (switching element) Tr2 is turned on, energy is stored in the reactor L and the transistor Tr2 is turned off. When boosted, the boost converter 23 that superimposes and outputs the energy accumulated in the reactor L to the voltage from the battery 12 via the diode (rectifier element) D1 corresponds to the “boost converter”. The first relay 41 disposed between the first reactor 41 and the reactor L corresponds to a “first switch”, and is connected to the battery 12 in parallel to the boost converter 23 on the boost converter 23 side of the first relay 41. The first capacitor 31 corresponds to a “first capacitor” and The second capacitor 32 connected in parallel with the inverter 22 corresponds to the “second capacitor”, the current sensor 37 for acquiring the battery current Ib flowing through the battery 12 corresponds to the “current acquisition means”, and the first capacitor 31 The voltage sensor 34 for acquiring the inter-terminal voltage VL corresponds to the “first voltage acquisition means”, the voltage sensor 35 for acquiring the terminal voltage VL of the second capacitor 32 corresponds to the “second voltage acquisition means”, The first relay 41 and the second relay 42 disposed between the first capacitor 31 and the reactor L correspond to the “second switch”, and are disposed between the reactor L of the boost converter 23 and the diode D1. The third relay 43 corresponds to a “third switch”, and the resistance element 33 connected in series to the reactor L and connected in parallel to the transistor Tr2 is “resistance”. It corresponds to. However, the correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the invention described in the column of means for solving the problem by the embodiment. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. In other words, the examples are merely specific examples of the invention described in the column of means for solving the problem, and the interpretation of the invention described in the column of means for solving the problem is It should be done based on the description.

  As mentioned above, although the embodiment of the present invention has been described using examples, the present invention is not limited to the above-described examples, and various modifications can be made without departing from the scope of the present invention. Needless to say.

  INDUSTRIAL APPLICABILITY The present invention can be used in the manufacturing industry of a power control device including an inverter, a boost converter having a reactor, a switching element, and a rectifying element, and first and second capacitors for smoothing.

  DESCRIPTION OF SYMBOLS 10 Electric vehicle, 11 Motor, 12 Battery, 16 Differential gear, 18a, 18b Driving wheel, 22 Inverter, 23 Boost converter, 31 1st capacitor, 32 2nd capacitor, 33, 36 Resistance element, 34, 35 Voltage sensor, 37 Current sensor, 38 Power line, 38a Positive bus, 38b Negative bus, 40 Electronic control unit, 41 First relay, 41a Positive relay, 41b Negative relay, 41c Avoidance relay, 41d Resistance element, 42 Second relay, 43 3rd relay, 51 start switch, 54 accelerator pedal, 55 accelerator pedal position sensor, 58 vehicle speed sensor, D1, D2 diode, Tr1, Tr2 transistor.

Claims (1)

An inverter that converts direct current power from the direct current power source into alternating current power, and stores the energy in the reactor when the switching element is turned on, and the voltage from the direct current power source via the rectifier element when the switching element is turned off A boost converter that superimposes and outputs the energy accumulated in the reactor, a first switch disposed between the DC power supply and the reactor of the boost converter, and the booster than the first switch. On the converter side, a first capacitor connected in parallel with the boost converter to the DC power supply, a second capacitor connected in parallel to the inverter with respect to the boost converter, and a current flowing through the DC power supply Current acquisition means for acquiring the first voltage acquisition means for acquiring the voltage across the terminals of the first capacitor, A power control device and a second voltage acquiring means for acquiring a terminal voltage of the second capacitor,
A second switch disposed between the first switch and the first capacitor and the reactor;
A third switch disposed between the reactor of the boost converter and the rectifying element;
And a resistor connected in series with the reactor and connected in parallel with the switching element.

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