VEHICLE ENERGY CONVERTER

Abstract

A vehicle power converter (1) mounted on a vehicle (Ve) comprises connectors, an AC-DC power conversion circuit (2), a smoothing capacitor (Cs), a bidirectional DC-DC power conversion circuit (3), switches provided between the smoothing capacitor (Cs) and at least one of the connectors, and a control unit.The control unit (4) executes the battery charging preparation operation when the control unit (4) detects that the vehicle power converter (1) is connected to the external power supply (P), as follows: after the control unit (4) controls the operation of the bidirectional DC-DC power conversion circuit (3) while maintaining a connection state between the smoothing capacitor (Cs) and the connectors in a disconnected state through the switch so that a current output from the battery (B) is supplied to the smoothing capacitor (Cs), the control unit (4) causes a connection state of the switch to change from a disconnected state to a connected state.

Description

BACKGROUND OF THE INVENTIONTechnical FieldThe present invention relates to a vehicular power converter.Prior ArtThere is known a vehicular power converter that operates as follows: converting an alternating current (AC) from an external power supply device such as a charging station into a direct current (DC) by rectifying the alternating current using an AC-DC power conversion circuit and smoothing the rectified alternating current using a smoothing capacitor; converting the direct current into a direct current corresponding to a target direct current using a bidirectional DC-DC power conversion circuit; and feeding the direct current into a battery mounted on a vehicle. Moreover, in this vehicular power converter, before outputting the power from the external power supply to the vehicular power converter, the smoothing capacitor is charged with a power output from the battery. This prevents a relatively large inrush current from flowing into the smoothing capacitor when the current is output from the external power supply to the vehicle power converter. Japanese Patent Application Publication No. 2022-054866 is known as a prior art of this vehicular power converter.When the external power supply device does not have a function of controlling power output, it may occur that the power is output from the external power supply device to the vehicle power converter at a time when the external power supply device and the vehicle power converter are connected to each other, i.e., when a connector of the charging station is inserted into the vehicle. This may result in the smoothing capacitor not being precharged.Here, another vehicular power converter having a circuit in which a resistor and a switch are provided on an input side of a smoothing capacitor, which are connected in parallel with each other, is known, wherein the vehicular power converter limits an inrush current flowing into the smoothing capacitor by the resistor, and switches the switch from the off position to the on position after the smoothing capacitor is charged.In such a vehicular power converter, however, the resistor and the switch are required to limit the inrush current flowing into the smoothing capacitor, which causes the manufacturing cost of the vehicular power converter to increase.The present invention is directed, in part, to suppressing an increase in the manufacturing cost of an in-vehicle power converter while suppressing a relatively large inrush current from flowing into a smoothing capacitor in the in-vehicle power converter when power is supplied from an external power supply to the in-vehicle power converter.SUMMARYAccording to an aspect of the present invention, there is provided a vehicular power converter mounted on a vehicle, the vehicular power converter including connectors to which a power output from an external power supply is input, an AC-DC power conversion circuit that, when power consumption at the connectors is an AC current, converts the AC current into a DC current by rectifying the AC current, a smoothing capacitor that smoothes the DC current rectified by the AC-DC power conversion circuit, a bidirectional DC-DC power conversion circuit that converts the DC current smoothed by the smoothing capacitor into a DC current corresponding to a target DC current and supplies the DC current to a battery mounted on the vehicle, a switch provided between the smoothing capacitor and at least one of the connectors, and a controller that controls the operation of the AC-DC power conversion circuit, the bidirectional DC-DC power conversion circuit, and the switch. The controller performs the battery charge preparation operation when the controller determines that the vehicle power converter is connected to the external power supply. In the battery charge preparation operation, after the controller controls the operation of the bidirectional DC-DC power conversion circuit while maintaining a connection state between the smoothing capacitor and the connectors in a disconnected state by the switch so that a current output from the battery is supplied to the smoothing capacitor, the controller causes a connection state of the switch to transition from a disconnected state to a connected state.Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.BRIEF DESCRIPTION OF THE FIGURESFor an understanding of the invention and the objects and advantages thereof, reference is made to the following description of the embodiments taken in conjunction with the accompanying figures, in which: FIG. 1 is a diagram showing an example of a vehicle power converter according to the present embodiment; FIG. 2A is a diagram showing an example of an AC-DC power conversion circuit, and FIG. 2B is an example of a bidirectional DC-DC power conversion circuit; FIG. 3 is a diagram showing a modified example 1 of the vehicle power converter according to the present embodiment; FIG. 4 is a diagram showing a modified example 2- 1 of the vehicle power converter according to the present embodiment; FIG. 5 is a diagram showing an example of a switching circuit shown in FIG. 4 ; FIG. 6 is a diagram showing a modified example 2- 2 of the vehicle power converter according to the present embodiment; FIG. 7 is a diagram showing an example of a switching circuit shown in FIG. 6 ; FIG. 8 is a diagram showing a modified example 2-3 of the vehicle power converter according to the present embodiment; FIG. 9 is a diagram showing a modified example 2-4 of the vehicular power converter according to the present embodiment; FIG. 10 is a diagram showing a modified example 3 of the vehicle power converter according to the present embodiment; FIG. 11 is a diagram showing a modified example 4 of the vehicle power converter according to the present embodiment; and FIG. 12 is a diagram showing a modified example 5 of the vehicle power converter according to the present embodiment.DETAILED DESCRIPTION OF THE EMBODIMENTSHereinafter, an embodiment of the present invention will be described in more detail with reference to the figures.FIG. 1 is a diagram showing an example of a vehicular power converter according to the present embodiment.A vehicle power converter 1 illustrated in FIG. 1 is mounted on a vehicle Ve such as an electric vehicle and a plug-in hybrid vehicle. The vehicular power converter 1 converts an alternating current (AC) supplied from an external power supply device Ch, e.g., a charging station, into a direct current (DC) corresponding to a target direct current, and supplies the direct current to a battery B mounted on the vehicle Ve.Note that the external power supply device Ch converts an alternating current output from an alternating current power supply P into a certain alternating current, and supplies the certain alternating current to the vehicle power converter 1. Here, the AC power supply P is an external power supply such as a commercial power supply.In addition, the battery B is a rechargeable battery, for example, a lithium ion secondary battery. The battery B serves as either a main battery for supplying power to a driving device such as a traction motor or an auxiliary battery for supplying power to electrical equipment such as an air compressor and an on-vehicle control device Cv that controls the travel of the vehicle Ve.In the example illustrated in FIG. 1, the alternating current output from the external power supply device Ch is supplied to the vehicle power converter 1 via a charging cable Ca; however, the alternating current output from the external power supply device Ch may be supplied to the vehicle power converter 1 wirelessly. In such a configuration, the vehicular power converter 1 includes a receiving power supply via which the alternating current is wirelessly received, the receiving power supply being connected to the connectors CL, CN, which will be described later.The vehicle power converter 1 also includes connectors CL, CN, a connector Cc, switches SW 1, SW 2, an AC-DC power conversion circuit 2, a bidirectional DC-DC power conversion circuit 3, a smoothing capacitor Cs, current sensors Si 1, Si 2, a voltage sensor Sv 1 (first voltage sensor), a voltage sensor Sv 2 (second voltage sensor), a voltage sensor Sv 3, a voltage sensor Sv 4, and a controller 4.The alternating current output from the alternating current power supply P is input to the connectors CL, CN via the external power supply device Ch. The connector CL is connected to a terminal of the AC-DC power conversion circuit 2 on an AC side thereof via a connection line (current-carrying conductor) L 11. In addition, the connector CL is connected to an output terminal OL of the external power supply device Ch via a connection line in the charging cable Ca. The connector CN is connected to the other terminal of the AC-DC power conversion circuit 2 on the AC side thereof via a connection line (neutral line) L 12. Moreover, the connector CN is connected to the other output terminal ON of the external power supply device Ch via the other power line in the charging cable Ca. The connector Cc is connected to the control device 4 via a signal line Lc. In addition, the connector Cc is connected to a terminal Oc of the external power supply device Ch via a signal line in the charging cable Ca. When the vehicle power converter 1 is connected to the external power supply device Ch via the charging cable Ca, power supply from the external power supply device Ch to the vehicle power converter 1 is ready, and the vehicle power converter 1 and the external power supply device Ch can communicate with each other.The switches SW 1, SW 2 are each formed of an electromagnetic relay having a normally closed contact (single-pole on / off switch). The switch SW 1 is provided between the connector CL and the smoothing capacitor Cs, and the switch SW 2 is provided between the connector CN and the smoothing capacitor Cs. The smoothing capacitor Cs will be described later. In the present embodiment, the switch SW 1 is provided on the connection line L 11 between the connector CL and the one terminal of the AC-DC power conversion circuit 2. In addition, the switch SW 2 is provided on a connection line L 12 between the connector CN and the other terminal of the AC-DC power conversion circuit 2. When the switches SW 1, SW 2 are turned on, the connectors CL, CN are electrically connected to the AC-DC power conversion circuit 2 (smoothing capacitor Cs). When at least one of the switches SW 1, SW 2 is turned off, the connectors CL, CN are electrically disconnected from the AC-DC power conversion circuit 2 (smoothing capacitor Cs). Note that one of the switches SW 1, SW 2 may be omitted, and only one switch of them may be present. When both switches SW 1, SW 2 are present, the connectors CL, CN are electrically disconnected from the smoothing capacitor Cs by the other switch even if one of them fails.The AC-DC power conversion circuit 2 converts the alternating current applied to the connectors CL, CN into a direct current by rectifying the alternating current.The smoothing capacitor Cs is provided between the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3. The direct current rectified by the AC-DC power conversion circuit 2 is smoothed by the smoothing capacitor Cs, and the smoothed current is output to the bidirectional DC-DC power conversion circuit 3. That is, one terminal of the smoothing capacitor Cs is connected to a connection line (plus line) L 21. The connection line L 21 connects one terminal of the AC-DC power conversion circuit 2 on a DC side thereof to one terminal of the bidirectional DC-DC power conversion circuit 3 on a side opposite to the battery B via the bidirectional DC-DC power conversion circuit 3. The connection line L 22 connects the other terminal of the AC-DC power conversion circuit 2 on the DC side thereof to the other terminal of the bidirectional DC-DC power conversion circuit 3 on the opposite side to the battery B via the bidirectional DC-DC power conversion circuit 3.The bidirectional DC-DC power conversion circuit 3 is provided between the smoothing capacitor Cs and the battery B. When the battery B is charged, the bidirectional DC-DC power conversion circuit 3 converts the direct current smoothed by the smoothing capacitor Cs into the direct current corresponding to the target direct current, and supplies the direct current to the battery B.The current sensor Si 1 is made of a Hall element, a shunt resistor, or the like. The current sensor Si 1 detects a current I 1 flowing through the connection line L 11 and sends the detected current I 1 to the controller 4.The voltage sensor Sv1 is composed of a voltage divider including resistors or the like. The voltage sensor Sv 1 detects a voltage V 1 between the connection line L 11 connecting the connector CL to the switch SW 1 and the connection line L 12 connecting the connector CN to the switch SW 2, and sends the detected voltage V 1 to the controller 4.The voltage sensor Sv2 is composed of a voltage divider including resistors or the like. The voltage sensor Sv 2 detects a voltage V 2 between the connection line L 11 connecting the switch SW 1 to the AC-DC power conversion circuit 2 and the connection line L 12 connecting the switch SW 2 to the AC-DC power conversion circuit 2, and sends the detected voltage V 2 to the controller 4.The voltage sensor Sv 3 is composed of a voltage divider including resistors or the like. The voltage sensor Sv 3 detects a voltage V 3 via the smoothing capacitor Cs, and sends the detected voltage V 3 to the controller 4.The current sensor Si 2 is made of a Hall element, a shunt resistor, or the like. The current sensor Si 2 detects a current I 2 flowing through the bidirectional DC-DC power conversion circuit 3 and sends the detected current I 2 to the controller 4.The voltage sensor Sv4 is composed of a voltage divider including resistors or the like. When the battery B is charged, the voltage sensor Sv 4 detects a voltage V 4 output from the bidirectional DC-DC power conversion circuit 3, and sends the detected voltage V 4 to the controller 4.<An Example of AC-DC Power Conversion Circuit 2>FIG. 2A is a diagram showing an example of the AC-DC power conversion circuit 2. Note that in FIG. 2A, the same components as in FIG. 1 are denoted by the same reference numerals.The AC-DC power conversion circuit 2 illustrated in FIG. 2A is a so-called Power Factor Correction (PFC) circuit, and includes an inductor L and the switching elements Q 1 to Q 4. Note that the switching elements Q 1 to Q 4 are each made of, for example, a metal oxide semiconductor field effect transistor (MOSFET).One terminal of the inductor L is connected to the connection line L 11, and the other terminal of the inductor L is connected to a node between a source terminal of the switching element Q 1 and a drain terminal of the switching element Q 2. A node between a source terminal of the switching element Q 3 and a drain terminal of the switching element Q 4 is connected to the connection line L 12. Drains of the switching elements Q 1, Q 3 are connected to one terminal of the smoothing capacitor Cs via the connection line L 21, and sources of the switching elements Q 2, Q 4 are connected to the other terminal of the smoothing capacitor Cs via the connection line L 22.While a positive current is input to the AC-DC power conversion circuit 2 (while the alternating current is a positive value) via the connection lines L 11, L 12, after the switching elements Q 2, Q 4 are turned on and the switching elements Q 1, Q 3 are turned off, the switching elements Q 1, Q 4 are turned on and the switching elements Q 2, Q 3 are turned off. This on-off operation is repeated in the sense described above. While negative power is input to the AC-DC power conversion circuit 2 via the connection lines L 11, L 12 (while the alternating current is a negative value), after the switching elements Q 1, Q 3 are turned on and the switching elements Q 2, Q 4 are turned off, the switching elements Q 2, Q 3 are turned on and the switching elements Q 1, Q 4 are turned off. This on-off operation is repeated in the manner described above. As a result, a power factor in the AC input of the AC-DC power conversion circuit 2 is corrected and the AC is rectified by the AC-DC power conversion circuit 2.Moreover, the AC-DC power conversion circuit 2 is a bidirectional circuit that can convert a direct current on one side of the smoothing capacitor Cs into an alternating current and output the converted alternating current to the connectors CL, CN.<An Example of Bidirectional DC-DC Power Conversion Circuit 3>FIG. 2B is a diagram showing an example of the bidirectional DC-DC power conversion circuit 3. Note that in FIG. 2B, the same components as in FIG. 1 are denoted by the same reference numerals.The bidirectional DC-DC power conversion circuit 3 illustrated in FIG. 2B includes a transformer Tr, switching elements Q 5 to Q 8 forming a bridge circuit on a primary side of the transformer Tr, switching elements Q 9 to Q 12 forming a bridge circuit on a secondary side of the transformer Tr, and a capacitor C provided on a battery B side. Note that the switching elements Q 5 to Q 12 are each made of, for example, a MOSFET.Drains of the switching elements Q 5, Q 7 are connected to one terminal of the smoothing capacitor Cs via the connection line L 21, and sources of the switching elements Q 6, Q 8 are connected to the other terminal of the smoothing capacitor Cs via the connection line L 22. A node between a source terminal of the switching element Q 5 and a drain terminal of the switching element Q 6 is connected to one terminal of a primary coil Lt 1 of the transformer Tr, and a node between a source terminal of the switching element Q 7 and a drain terminal of the switching element Q 8 is connected to the other terminal of the primary coil Lt 1 of the transformer Tr. Drains of the switching elements Q 9, Q 11 are connected to one terminal of the capacitor C, and sources of the switching elements Q 10, Q 12 are connected to the other terminal of the capacitor C. A node between a source terminal of the switching element Q 9 and a drain terminal of the switching element Q 10 is connected to one terminal of a secondary coil Lt 2 of the transformer Tr, and a node between a source terminal of the switching element Q 11 and a drain terminal of the switching element Q 12 is connected to the other terminal of the secondary coil Lt 2 of the transformer Tr. One terminal of the capacitor C is connected to a positive terminal of the battery B illustrated in FIG. 1, and the other terminal of the capacitor C is connected to a negative terminal of the battery B.Note that a configuration of the bidirectional DC-DC power conversion circuit 3 is not limited to a circuit configuration illustrated in FIG. 2B as long as the bidirectional DC-DC power conversion circuit 3 converts the direct current smoothed by the smoothing capacitor Cs into the direct current corresponding to the target direct current and supplies the direct current to the battery B, and also converts the direct current output of the battery B into a certain direct current and supplies the certain direct current to the smoothing capacitor Cs.< Of Control Apparatus 4>The control device 4 shown in FIG. 1 consists of a processor or a programmable module such as a field programmable gate array (FPGA) and a programmable logic circuit (PLD). The controller 4 controls the operations of the AC-DC power conversion circuit 2, the bidirectional DC-DC power conversion circuit 3, and the switches SW 1, SW 2. Note that the operation of the AC-DC power conversion circuit 2 and the switches SW 1, SW 2 may be controlled by a controller other than the controller 4. In this case, the controller 4 cooperates with the other controller to control the operation of the bidirectional DC-DC power conversion circuit 3.<Operation of Control Apparatus 4>1) Previously, the connectors CL, CN are electrically disconnected from the smoothing capacitor Cs by the switches SW 1, SW 2. When the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply device Ch, the controller 4 first controls the operation of the bidirectional DC-DC power conversion circuit 3 while maintaining a connection state between the smoothing capacitor Cs and the connectors CL, CN in the disconnected state by the switches SW 1, SW 2, so that the current output from the battery B is supplied to the smoothing capacitor Cs to pre-charge the smoothing capacitor Cs. That is, when the controller 4 determines that the vehicle power converter 1 is connected to the external power supply device Ch, the controller 4 performs a battery charge preparing operation. The battery charge preparation operation is a process in which the controller 4 controls the operation of the bidirectional DC-DC power conversion circuit 3 while keeping the connection state between the smoothing capacitor Cs and the connectors CL, CN in the disconnected state by the switches SW 1, SW 2 so that the current output from the battery B is supplied to the smoothing capacitor Cs, the controller 4 causes a connection state of each of the switches SW 1, SW 2 to transition from a disconnected state to a connected state by turning the switches SW 1, SW 2 on from off. Note that the controller 4 maintains the connection state between the smoothing capacitor Cs and the connectors CL, CN in the disconnected state by the switches SW 1, SW 2 from an end of the previous charging of the battery B to an end of the pre-charging of the smoothing capacitor Cs. Moreover, a maximum current flowing from the battery B through the bidirectional DC-DC power conversion circuit 3 into the smoothing capacitor Cs when the smoothing capacitor Cs is precharged is, for example, a rated current of the smoothing capacitor Cs or less.2) Subsequently, when the pre-charging of the smoothing capacitor Cs is completed, the controller 4 causes a connection state between the AC power supply P and the vehicle power converter 1 to transition from a disconnected state to a connected state by turning on both switches SW 1, SW 2 (the battery charge preparing operation ends).3) Subsequently, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the direct current corresponding to the target direct current, which is sent from the on-vehicle controller Cv to the controller 4, is output to the battery B.4) When the target direct current transmitted from the on-vehicle controller Cv to the controller 4 reaches zero or when a command to end the charging of the battery B is transmitted from the on-vehicle controller Cv to the controller 4, the controller 4 stops the operation of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 and causes the connection state between the smoothing capacitor Cs and the connectors CL, CN to transition from the connected state to the disconnected state via the switches SW 1, SW 2.<Example of Operation of Control Apparatus 4 when Control Apparatus 4 Determines that Vehicular Energy Converter 1 is Connected to Alternating Current Power Supply P via External Power Supply Device Ch>When the controller 4 detects a signal that runs via the signal line in the charging cable Ca and the signal line Lc, the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch. Note that the above-described signal is, for example, a proximity detection (PISW) signal. When the vehicle power converter 1 is connected to the external power supply device Ch via the charging cable Ca, the PISW signal is input to a PISW port on one side of the vehicle power converter 1 and detected by the controller 4. The above-described signal may be, for example, a CPLT (Control Pilot Line) signal. When the vehicle power converter 1 is connected to the external power supply device Ch via the charging cable Ca, the CPLT signal is input to a CPLT terminal on the vehicle power converter 1 side and detected by the controller 4. Note that the phrase "determines that the vehicular power converter 1 is connected to the AC power supply P" includes a state in which the vehicular power converter 1 is actually connected to the AC power supply P.Alternatively, when the controller 4 receives a command to start charging of the battery B sent from the on-vehicle controller Cv, the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch. Note that the on-vehicle control device Cv transmits the command for starting the charging of the battery B to the control device 4 based on the operation by the user, a remaining capacity of the battery B, or the like.Alternatively, in a case where the alternating current is wirelessly output from the external power supply Ch to the vehicle power converter 1, when establishing communication for preparing the charging between the control device 4 and the external power supply Ch, the control device 4 determines that the vehicle power converter 1 is connected to the alternating current P via the external power supply Ch.Alternatively, when the controller 4 acquires, from the vehicle-side controller Cv, the information that the vehicle Ve approaches the external power supply Ch, the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch. Note that the following. When the in-vehicle controller Cv determines that the vehicle Ve approaches the external power supply Ch, the in-vehicle controller Cv transmits the information that the vehicle Ve approaches the external power supply Ch to the controller 4 using a global positioning system (GPS) signal mounted on the vehicle Ve.Alternatively, in the following cases, the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply device Ch: after a first case where an operation or instruction is performed by which a cover provided on an outer surface of the vehicle Ve and covering the connectors CL, CN is opened, or a sensor not shown detects such an operation of the cover, the controller 4 receives the information from the vehicle-side controller Cv; and a second case where the controller 4 receives the information from the vehicle-side controller Cv after the sensor not shown detects that a driver or the like approaches the connectors CL, CN with a key fob.Alternatively, the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch when the voltage sensor Sv 1 detects an AC voltage V 1 applied from the external power supply Ch.<Example of Operation of Control Unit 4 Upon Termination of Precharge of Smoothing Capacitor Cs>In precharging the smoothing capacitor Cs, when the voltage V 3 detected by the voltage sensor Sv 3 is a voltage threshold value Vth 3 or more, the controller 4 determines that the smoothing capacitor Cs is sufficiently charged (the smoothing capacitor Cs is filled with electric charge), and causes the connection state between the smoothing capacitor Cs and the connectors CL, CN to transition from the disconnected state to the connected state via the switches SW 1, SW 2. Note that, for example, when the alternating current is output from the external power supply Ch to the vehicle power converter 1, the voltage threshold Vth 3 is defined as a peak voltage of the alternating voltage between the connection line L 11 and the connection line L 12 or a maximum voltage of the direct voltage between the connection line L 21 and the connection line L 22. The voltage threshold Vth 3 may be determined in advance, may be determined or estimated from a value of the voltage sensor Sv 1, or may be set to a value corresponding to the output voltage of the connected external power supply device Ch when the output voltage has already been determined.Alternatively, when pre-charging the smoothing capacitor Cs, the controller 4 determines that the smoothing capacitor Cs is sufficiently charged when the current flowing from the battery B into the smoothing capacitor Cs and detected by the current sensor Si 2 is a threshold current or less, and causes the connection state between the smoothing capacitor Cs and the connectors CL, CN to transition from the disconnected state to the connected state via the switches SW 1, SW 2. Alternatively, a current sensor may be provided that is connected in series with the smoothing capacitor Cs, and the current flowing from the battery B into the smoothing capacitor Cs may be detected by the current sensor. Note that a threshold current is set to zero, for example. Alternatively, the current flowing from the battery B into the smoothing capacitor Cs may be accumulated, and when the accumulated current amount exceeds a certain threshold current, the controller 4 may determine that the smoothing capacitor Cs is sufficiently charged, and cause the connection state between the smoothing capacitor Cs and the connectors CL, CN to transition from the disconnected state to the connected state via the switches SW 1, SW 2.Alternatively, in the battery charge preparation operation, the controller 4 determines that the smoothing capacitor Cs is sufficiently charged when a certain time t has elapsed since the start of the power supply from the battery B to the smoothing capacitor Cs, and causes the connection state between the smoothing capacitor Cs and the connectors CL, CN to transition from the disconnected state to the connected state by turning the switches SW 1, SW 2 from off to on. Here, the specified time t is equal to or longer than the time required for the voltage across the smoothing capacitor Cs to reach such a voltage that the current flowing from the AC-DC power conversion circuit 2 to the smoothing capacitor Cs when the connection state between the smoothing capacitor Cs and the connectors CL, CN enters the connected state through the switches SW 1, SW 2 is equal to or less than an allowable current of the smoothing capacitor Cs. Moreover, the specified time t is equal to or shorter than the time required for the voltage across the smoothing capacitor Cs to reach the peak voltage of the alternating current supplied from the external power supply Ch or the voltage of the direct current supplied from the AC-DC power conversion circuit 2. The determined time t may be determined by experiment in advance or calculated based on the voltage across the battery B. By thus controlling the battery charge preparation operation in time, the time required from the start of the current supply from the battery B to the smoothing capacitor Cs until the connection state between the smoothing capacitor Cs and the connectors CL, CN transitions from the disconnected state to the connected state through the switches SW 1, SW 2 is shortened by a certain time, compared with a case where the voltage across the smoothing capacitor Cs or the current flowing into the smoothing capacitor Cs is detected and whether the smoothing capacitor Cs is sufficiently charged is determined from the detected voltage or the current. Here, the determined time is a time required to convert the analog values detected by the voltage sensor and the current sensor into digital values. Moreover, this management prevents the smoothing capacitor Cs from being damaged when the connection state between the smoothing capacitor Cs and the connectors CL, CN is switched from the disconnected state to the connected state by the switches SW 1, SW 2. That is, the time required from the connection of the vehicular power converter 1 to the AC power supply P via the external power supply device Ch until the start of the charging of the battery B is shortened.In addition, the controller 4 may be configured such that the controller 4 changes the predetermined time t (the voltage threshold Vth 3, the threshold current, the predetermined threshold current in the accumulated current amount) depending on the voltage V 1 detected by the voltage sensor Sv 1. Specifically, for example, the controller 4 may be configured such that the controller 4 shortens the specified time t as the voltage V 1 decreases. When the output voltage of the external power supply device Ch is relatively low, the current flowing from the external power supply device Ch into the vehicle power converter 1 is normally relatively low. For this reason, even when the predetermined time t is shortened, the current flowing from the external power supply device Ch into the smoothing capacitor Cs when the connection state between the smoothing capacitor Cs and the connectors CL, CN is switched from the disconnected state to the connected state by the switches SW 1, SW 2 is relatively small. Accordingly, the smoothing capacitor Cs is charged only as far as the output voltage of the external power supply device Ch requires, so that the time from the start of supply of the power from the battery B to the smoothing capacitor Cs until the transition of the connection state between the smoothing capacitor Cs and the connectors CL, CN through the switches SW 1, SW 2 from the disconnected state to the connected state is shortened as compared with a case where the predetermined voltage, the predetermined current, or the predetermined time are set according to the assumed maximum output voltage of the external power supply device Ch. That is, the time required from the connection of the vehicular power converter 1 to the AC power supply P via the external power supply device Ch until the start of the charging of the battery B is shortened.<Example of Operation of Control Unit 4 in Determining Whether At Least One of Switches SW 1, SW 2 Is Fused>When the alternating current is output from the alternating current power supply P to the vehicle power converter 1 via the external power supply device Ch and the connection state between the smoothing capacitor Cs and the connectors CL, CN is maintained in the disconnected state by the switches SW 1, SW 2, the controller 4 determines that at least one of the switches SW 1, SW 2 is fused in a case where the voltage V 1 detected by the voltage sensor Sv 1 is a voltage threshold Vth 1 (first voltage threshold) or more and the voltage V 2 detected by the voltage sensor Sv 2 is a voltage threshold Vth 2 (second voltage threshold) or more. This makes it possible to determine whether at least one of the switches SW 1, SW 2 is secured. When only one of the switches SW 1, SW 2 is present in the vehicle power converter 1, the controller 4 determines that the switch is fused when the voltage V 1 detected by the voltage sensor Sv 1 is the voltage threshold Vth 1 or more and the voltage V 2 detected by the voltage sensor Sv 2 is the voltage threshold Vth 2 or more.<Example of Operation of Control Unit 4 After Switching State Between Smoothing Capacitor Cs and Connectors CL, CN from Disconnected State to Connected State By Switches SW 1, SW 2>When the battery B is charged, the controller 4 controls the driving of the switching elements Q 1 to Q 4 by outputting the driving signals S 1 to S 4 using the current I 1 detected by the current sensor Si 1, the voltage V 2 detected by the voltage sensor Sv 2, and the voltage V 3 detected by the voltage sensor Sv 3. At this time, the controller 4 controls the driving of the switching elements Q 1 to Q 4 such that a phase difference between the AC input to the AC-DC power conversion circuit 2 and the AC input to the AC-DC power conversion circuit 2 becomes zero, that is, the power factor in the AC input to the AC-DC power conversion circuit 2 becomes one. In this control, the current rectified by the AC-DC power conversion circuit 2 having the corrected power factor is supplied to the smoothing capacitor Cs.Moreover, when charging the batteries B, the controller 4 controls the driving of the switching elements Q 5 to Q 8 by outputting the driving signals S 5 to S 8 and the driving of the switching elements Q 9 to Q 12 by outputting the driving signals S 9 to S 12 so that the direct current supplied from the bidirectional DC-DC power conversion circuit 3 to the battery B follows the target direct current. The target direct current is set based on, for example, the voltage across the battery B when a constant current charge control is switched to a constant voltage charge control, or based on the current flowing through the battery B when the constant voltage charge control ends. For example, a duty ratio of each of the drive signals S 5 to S 12 is set to 50 [%]. In addition, the drive signal S 5 is synchronized with the drive signal S 8, the drive signal S 6 is synchronized with the drive signal S 7, the drive signal S 9 is synchronized with the drive signal S 12 and the drive signal S 10 is synchronized with the drive signal S 11. A phase of the drive signal S 5 and S 8 is shifted 180 degrees from a phase of the drive signal S 6 and S 7, and a phase of the drive signal S 9 and S 12 is shifted 180 degrees from a phase of the drive signal S 10 and S 11. A dead time is provided between a rise time of the drive signal S 5 and a fall time of the drive signal S 6, and between a fall time of the drive signal S 5 and a rise time of the drive signal S 6. A dead time is provided between a rise time of the drive signal S 7 and a fall time of the drive signal S 8, and between a fall time of the drive signal S 7 and a rise time of the drive signal S 8. A dead time is provided between a rise time of the drive signal S 9 and a fall time of the drive signal S 10, and between a fall time of the drive signal S 9 and a rise time of the drive signal S 10. A dead time is provided between a rise time of the drive signal S 11 and a fall time of the drive signal S 12 and between a fall time of the drive signal S 11 and a rise time of the drive signal S 12.<Example of Operation of Control Apparatus 4 when Alternating Current is Output to Connectors CL, CN>When the controller 4 is instructed by a user to convert the power supplied from the battery B into AC power and output the AC power to the outside of the vehicle power converter 1 via the connectors CL, CN, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the DC power output from the battery B is converted into AC power and the converted AC power is output to the outside of the vehicle power converter 1 via the connectors CL, CN.Next, an effect of the vehicular power converter 1 according to the present embodiment will be described.< Effect>When supplying the vehicle power converter 1 with power from the AC power supply P, for example, there may be a case where the vehicle power converter 1 is connected to the AC power supply P via the external power supply device Ch and the external power supply device Ch has no function of controlling a power output timing (e.g., a charge control method of the external power supply device Ch is not standard or has only the MODE 1). In this case, the alternating current from the alternating current power supply P may be supplied to the vehicle power converter 1 at a time when the vehicle power converter 1 is connected to the external power supply device Ch, that is, at a time when the connector of the charging station is inserted into the vehicle Ve.When the controller 4 in the vehicular power converter 1 of the present embodiment determines that the vehicular power converter 1 is connected to the AC power supply P via the external power supply Ch, the controller 4 performs the battery charge preparing operation. Specifically, the connection state between the smoothing capacitor Cs and the connectors CL, CN is maintained in the cut state by the switches SW 1, SW 2, thereby suppressing the power supply to the smoothing capacitor Cs. In addition, in the battery charge preparation operation, the smoothing capacitor Cs is precharged by supplying the current from the battery B to the smoothing capacitor Cs. When the precharge of the smoothing capacitor Cs is completed, the controller 4 causes the connection state between the smoothing capacitor Cs and the connectors CL, CN to transition from the disconnected state to the connected state through the switches SW 1, SW 2, enabling the supply of the power from the AC power supply P to the smoothing capacitor Cs.Thereby, even when the external power supply device Ch does not have a function of timing the current output, it is suppressed that the current from the AC power supply P is supplied to the smoothing capacitor Cs via the external power supply device Ch before the smoothing capacitor Cs is sufficiently charged. This suppresses a relatively large inrush current from flowing into the smoothing capacitor Cs. In addition, a resistor need not be provided to limit the inrush current flowing into the smoothing capacitor Cs, so that an increase in the manufacturing cost of the vehicular power converter 1 is suppressed.< Effect>When precharging the smoothing capacitor Cs, the controller 4 may determine that the smoothing capacitor Cs is sufficiently charged (the smoothing capacitor Cs is filled with electric charge) when the voltage V 3 detected by the voltage sensor Sv 3 is the voltage threshold value Vth 3 or more, and transition the connection state between the smoothing capacitor Cs and the connectors CL, CN from the disconnected state to the connected state via the switches SW 1, SW 2.This control securely suppresses a relatively large inrush current from flowing into the smoothing capacitor Cs.< Effect>In the battery charge preparation operation, when the certain time t has elapsed from the start of the power supply from the battery B to the smoothing capacitor Cs, the controller 4 may transition the connection state between the smoothing capacitor Cs and the connectors CL, CN from the disconnected state to the connected state. The specified time t is equal to or longer than the time required for the voltage across the smoothing capacitor Cs to reach the voltage so that the current flowing from the AC-DC power conversion circuit 2 to the smoothing capacitor Cs when the connection state between the smoothing capacitor Cs and the connectors CL, CN enters the connected state through the switches SW 1, SW 2 is equal to or less than the allowable current of the smoothing capacitor Cs. In addition, the specified time t is equal to or shorter than the time required for the voltage across the smoothing capacitor Cs to reach the peak voltage of the alternating current supplied from the external power supply device Ch or the voltage of the direct current supplied from the AC-DC power conversion circuit 2.By thus controlling the battery charge preparation operation in time, the time that passes from the start of the current supply from the battery B to the smoothing capacitor Cs to the transition of the connection state between the smoothing capacitor Cs and the connectors CL, CN from the disconnected state to the connected state by the switches SW 1, SW 2 is shortened compared with the case where the voltage across the smoothing capacitor Cs or the current flowing into the smoothing capacitor Cs is detected and whether the smoothing capacitor Cs is sufficiently charged is determined from the detected voltage or the current. Moreover, this management prevents the smoothing capacitor from being damaged when the connection state between the smoothing capacitor Cs and the connectors CL, CN is switched from the disconnected state to the connected state by the switches SW 1, SW 2. That is, the time required from the connection of the vehicular power converter 1 to the AC power supply P via the external power supply device Ch until the start of the charging of the battery B is shortened.< Effect>The specific time t (the voltage threshold Vth 3, the threshold current, or the predetermined threshold current in the accumulated current amount) may be changed depending on the voltage V 1 detected by the voltage sensor Sv 1, for example, the specific time t may be concretely shortened as the voltage V 1 decreases.Since the output value of the external power supply device Ch is generally relatively low, the current flowing from the external power supply device Ch to the vehicle power converter 1 is relatively low. For this reason, the time from the start of the current supply from the battery B to the smoothing capacitor Cs to the transition of the connection state between the smoothing capacitor Cs and the connectors CL, CN from the disconnected state to the connected state is shortened by the switches SW 1, SW 2. That is, the time from the connection of the vehicular power converter 1 to the AC power supply P via the external power supply device Ch to the start of the charging of the battery B is shortened.< Effect>The AC-DC power conversion circuit 2 is the bidirectional circuit that can convert the direct current on the smoothing capacitor Cs side into the alternating current and output the converted alternating current to the connectors CL, CN. When the controller 4 is instructed by the user to convert the power supplied from the battery B into AC power and output the AC power to the outside of the vehicle power converter 1 via the connectors CL, CN, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the DC power output from the battery B is converted into AC power and the converted AC power is output to the outside of the vehicle power converter 1 via the connectors CL, CN. Thus, the vehicle power converter is usable not only for charging but also as a power source of the alternating current.< Effect>The vehicle power converter 1 includes the switches SW 1, SW 2, the voltage sensor Sv 1, and the voltage sensor Sv 2. With this configuration, when the alternating current is output from the alternating current power supply P to the vehicle power converter 1 via the external power supply device Ch and the connection state between the smoothing capacitor Cs and the connectors CL, CN is maintained in the disconnected state by the switches SW 1, SW 2, the controller 4 determines that at least one of the switches SW 1, SW 2 is fused when the voltage V 1 detected by the voltage sensor Sv 1 is the voltage threshold Vth 1 (first voltage threshold) or more and the voltage V 2 detected by the voltage sensor Sv 2 is the voltage threshold Vth 2 (second voltage threshold) or more. It is thus possible to determine whether at least one of the switches SW 1, SW 2 is secured.< Example 1>FIG. 3 is a diagram showing a modified example 1 of the vehicle power converter 1 according to the present embodiment. Note that in FIG. 3, the same components as in FIG. 1 are denoted by the same reference numerals, so their description is omitted. Moreover, a vehicle compartment power supply section Co illustrated in FIG. 3 is an outlet port provided in the vehicle Ve from which the alternating current is supplied to a vehicle compartment. To the vehicle compartment power supply section Co, a load such as an electric appliance is connected, which is not illustrated. When the alternating current is supplied from the vehicle power converter 1 to the vehicle compartment power supply section Co in a state where a load is connected to the vehicle compartment power supply section Co, the alternating current is supplied to the load.The vehicle energy converter 1 shown in FIG. 3 differs from the vehicle energy converter 1 shown in FIG. 1 in that the switches SW 3, SW 4 are provided instead of the switches SW 1, SW 2.For example, the switches SW 3, SW 4 are each formed of an electromagnetic relay having a double-throw contact (single-pole switching relay). One terminal COM each of the switches SW 3, SW 4 is connected to the AC-DC power conversion circuit 2. One terminal NC each of the switches SW 3, SW 4 is connected to the vehicle compartment power supply section Co. A terminal NO of the switch SW 3 is connected to the connector CL, and a terminal NO of the switch SW 4 is connected to the connector CN.When the terminal COM of each of the switches SW 3, SW 4 is connected to the corresponding terminal NC of the switches SW 3, SW 4, the AC-DC power conversion circuit 2 is connected to the vehicle compartment power supply section Co. In this case, the connection state between the smoothing capacitor Cs and the connectors CL, CN is switched to the disconnected state by the switches SW 3, SW 4. Note that even when the terminal COM of at least one of the switches SW 3, SW 4 is connected to the corresponding terminal NC, the connection state between the smoothing capacitor Cs and the connectors CL, CN is also referred to as a disconnected state.When the terminal COM of each of the switches SW 3, SW 4 is connected to the corresponding terminal NO of the switches SW 3, SW 4, the AC-DC power conversion circuit 2 is connected to the connectors CL, CN. In this case, the connection state between the smoothing capacitor Cs and the connectors CL, CN is switched to the connected state by the switches SW 3, SW 4.<Example of Operation of Control Unit 4 When Battery B> Is ChargedFirst, when the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch, the controller 4 controls the switches SW 3, SW 4 so that the terminal COM of at least one of the switches SW 3, SW 4 is connected to the terminal NC. In this case, the connection state between the smoothing capacitor Cs and the connectors CL, CN is switched to the disconnected state by the switches SW 3, SW 4. In addition, the controller 4 controls the operation of the bidirectional DC-DC power conversion circuit 3 to precharge the smoothing capacitor Cs. Note that stopping the operation of the AC-DC power conversion circuit 2 when the smoothing capacitor Cs is precharged prevents the alternating current output from the AC-DC power conversion circuit 2 from being output to an outside of the vehicle power converter 1 via the vehicle compartment power supply section Co.Subsequently, when the precharge of the smoothing capacitor Cs is completed, the controller 4 controls the switches SW 3, SW 4 so that the terminal COM of the respective switch SW 3, SW 4 is connected to the corresponding terminal NO of the switches SW 3, SW 4. In this case, the connection state between the smoothing capacitor Cs and the connectors CL, CN is switched to the connected state by the switches SW 3, SW 4.Then, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the alternating current output from the external power supply device Ch is converted into the direct current corresponding to the target direct current and the direct current is supplied to the battery B.<Example of Operation of Control Unit 4 When Inputted to Vehicle Room Power Supply Section Co>First, when the controller 4 receives a command to power the vehicle compartment power supply section Co sent from the vehicle-side controller Cv, the controller 4 controls the switches SW 3, SW 4 so that the terminal COM of each of the switches SW 3, SW 4 is connected to the corresponding terminal NC of the switches SW 3, SW 4.Then, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the direct current output from the battery B is converted into alternating current and the alternating current is supplied to the vehicle compartment power supply section Co.The vehicular power converter 1 according to the modified example 1 provides the same effects as the first to sixth effects. The vehicular power converter 1 according to the modified example 1 also provides the following seventh effect.< Effect>The vehicle Ve includes the vehicle compartment power supply section Co that supplies the vehicle compartment with alternating current, and the AC-DC power conversion circuit 2 is the bidirectional circuit that can convert the direct current on the smoothing capacitor Cs side into the alternating current and output the converted alternating current to the connectors. The switches SW 3, SW 4 are provided between the AC-DC power conversion circuit 2 and the connectors CL, CN instead of the switches SW 1, SW 2, and connect the AC-DC power conversion circuit 2 to the connectors CL, CN or connect the AC-DC power conversion circuit 2 to the vehicle compartment power supply section Co. Accordingly, the switches SW 3, SW 4 are also used as the switches SW 1, SW 2, which prevents an increase in manufacturing cost of the vehicle power converter 1 having a function of supplying power to the vehicle compartment power supply section Co.< Example 2-1>FIG. 4 is a diagram showing a modified example 2- 1 of the vehicle power converter 1 according to the present embodiment. Note that in FIG. 4, the same components as in FIG. 3 are denoted by the same reference numerals, and the description of these components is omitted.The vehicular power converter 1 illustrated in FIG. 4 is different from the vehicular power converter 1 illustrated in FIG. 3 in that a three-phase AC output of the external power supply device Ch is converted into the DC current corresponding to the target DC current and the DC current is supplied to the battery B. Note that the external power supply device Ch converts an R-phase alternating current of the three-phase alternating current of the alternating current power supply P into a certain alternating current and outputs the certain alternating current at a terminal R, converts an S-phase alternating current of the three-phase alternating current of the alternating current power supply P into a certain alternating current and outputs the certain alternating current at a terminal S, and converts a T-phase alternating current of the three-phase alternating current of the alternating current power supply P into a certain alternating current and outputs the certain alternating current at a terminal T. Further, a terminal n of the external power supply device Ch is connected to a neutral point of the AC power supply P.The vehicle energy converter 1 shown in FIG. 4 contains the connectors CR, CS, CT, Cn as well as a switching circuit 5 instead of the connectors CL, CN.When the vehicle power converter 1 is connected to the external power supply device Ch via the charging cable Ca, the connectors CR, CS, CT, Cn of the vehicle power converter 1 are connected to the terminals R, S, T, n of the external power supply device Ch, respectively.The AC-DC power conversion circuit 2 illustrated in FIG. 4 includes the inductors L 1 to L 3 and the switching elements Q 13 to Q 18. Note that the switching elements Q 13 to Q 18 are each formed of a MOSFET, for example.One terminal of the inductor L 1 is connected to a connection line L 31, and the other terminal of the inductor L 1 is connected to a node between a source terminal of the switching element Q 13 and a drain terminal of the switching element Q 14. One terminal of the inductor L 2 is connected to a connection line L 32, and the other terminal of the inductor L 2 is connected to a node between a source terminal of the switching element Q 15 and a drain terminal of the switching element Q 16. One terminal of the inductor L 3 is connected to a connection line L 33, and the other terminal of the inductor L 3 is connected to a node between a source terminal of the switching element Q 17 and a drain terminal of the switching element Q 18.Moreover, the AC-DC power conversion circuit 2 is the bidirectional circuit that can convert the direct current on the smoothing capacitor Cs side into a single-phase alternating current and output the single-phase alternating current to the connectors CR, Cn (the vehicle compartment power supply section Co described later).The controller 4 controls the operation of the switching circuit 5 to switch between a state in which the power output from the external power supply Ch is ready to be supplied to the battery B and a state in which the power output from the battery B is ready to be supplied to the vehicle compartment power supply section Co.FIG. 5 is a schematic diagram showing an example of the switching circuit 5 shown in FIG. 4.The switching circuit 5 illustrated in FIG. 5 includes switches SW 3, SW 4, switches SW 5 to SW 7, voltage sensors Sv 5 to Sv 10, and current sensors Si 3 to Si 5.The switch SW 3 is provided on the connection line L 31. Specifically, the terminal COM, the terminal NC, and the terminal NO of the switch SW 3 are connected to the inductor L 1, the vehicle compartment power supply portion Co, and the connector CR, respectively. That is, the switch SW 3 connects the inductor L 1 to the connector CR or the vehicle compartment power supply portion Co.The switches SW 4, SW 5 are provided with a connection line L 34 connecting the connector Cn and a node between the switching elements Q 17, Q 18. Specifically, the terminal COM, the terminal NC, and the terminal NO of the switch SW 4 are connected to a terminal NO of the switch SW 5, the vehicle compartment power supply portion Co, and the connector Cn, respectively. Here, the switch SW 5 is constituted by an electromagnetic relay having a normally-open switch, and a terminal COM of the switch SW 5 is connected to the node between the switching elements Q 17, Q 18. That is, the switch SW 4 connects the node between the switching elements Q 17, Q 18 to the connector Cn and the vehicle compartment power supply section Co, respectively.The switch SW 6 is provided on the connection line L 32. Specifically, the switch SW 6 is formed of an electromagnetic relay having a changeover contact. A terminal COM, a terminal NC, and a terminal NO of the switch SW 6 are connected to the inductor L 2, the connector CR, and the connector CS, respectively. That is, the switch SW 6 connects the inductor L 2 to the connector CR or the connector CS.The switch SW 7 is provided on the connection line L 33. Specifically, the switch SW 7 is formed of an electromagnetic relay having a normally open switch. A terminal COM and a terminal NO of the switch SW 7 are connected to the inductor L 3 and the connector CT, respectively.One terminal of the voltage sensor Sv 5 is connected between the switch SW 3 and the connector CR, and the other terminal of the voltage sensor Sv 5 is connected between the switch SW 4 and the connector Cn. One terminal of the voltage sensor Sv 6 is connected between the switch SW 6 and the connector CS, and the other terminal of the voltage sensor Sv 6 is connected between the switch SW 4 and the connector Cn. One terminal of the voltage sensor Sv 7 is connected between the switch SW 7 and the connector CT, and the other terminal of the voltage sensor Sv 7 is connected between the switch SW 4 and the connector Cn. The voltage sensors Sv 5, Sv 6, and Sv 7 measure a voltage between the connection line L 31 and the connection line L 34, a voltage between the connection line L 32 and the connection line L 34, and a voltage between the connection line L 33 and the connection line L 34, respectively. In addition, one terminal of the voltage sensor Sv 8 is connected between the switch SW 3 and the AC-DC power conversion circuit 2, and the other terminal of the voltage sensor Sv 8 is connected between the switch SW 5 and the AC-DC power conversion circuit 2. One terminal of the voltage sensor Sv 9 is connected between the switch SW 6 and the AC-DC power conversion circuit 2, and the other terminal of the voltage sensor Sv 6 is connected between the switch SW 5 and the AC-DC power conversion circuit 2. One terminal of the voltage sensor Sv 10 is connected between the switch SW 7 and the AC-DC power conversion circuit 2, and the other terminal of the voltage sensor Sv 10 is connected between the switch SW 5 and the AC-DC power conversion circuit 2. The voltage sensors Sv 8, Sv 9, and Sv 10 respectively measure a voltage between the connection line L 31 and the connection line L 34, a voltage between the connection line L 32 and the connection line L 34, and a voltage between the connection line L 33 and the connection line L 34. In addition, current sensors Si3, Si4, Si5 are provided on the connection line L31, L32, and L33, respectively. The current sensors Si 3, Si 4, Si 5 measure a current flowing through an inductor L 1, a current flowing through an inductor L 2, and a current flowing through an inductor L 3, respectively.Note that the connection of the voltage sensors Sv 5 to Sv 10 is not limited to the example described above, but may also be as follows: one terminal of the voltage sensor Sv 5 is connected between the switch SW 3 and the connector CR, and the other terminal of the voltage sensor Sv 5 is connected between the switch SW 6 and the connector CS; one terminal of the voltage sensor Sv 6 is connected between the switch SW 6 and the connector CS, and the other terminal of the voltage sensor Sv 6 is connected between the switch SW 7 and the connector CT; one terminal of the voltage sensor Sv 7 is connected between the switch SW 7 and the connector CT, and the other terminal of the voltage sensor Sv 7 is connected between the switch SW 3 and the connector CR; the voltage sensors SV 5, SV 6, SV 7 measure a voltage between the connection line L 31 and the connection line L 32, a voltage between the connection line L 32 and the connection line L 33, and a voltage between the connection line L 33 and the connection line L 31, respectively; a terminal of the voltage sensor Sv 8 is connected between the switch SW 3 and the AC-DC power conversion circuit 2, and the other terminal of the voltage sensor Sv 8 is connected between the switch SW 6 and the AC-DC power conversion circuit 2; a terminal of the voltage sensor Sv 9 is connected between the switch SW 6 and the AC-DC power conversion circuit 2, and the other terminal of the voltage sensor Sv 9 is connected between the switch SW 7 and the AC-DC power conversion circuit 2; one terminal of the voltage sensor Sv 10 is connected between the switch SW 7 and the AC-DC power conversion circuit 2, and the other terminal of the voltage sensor Sv 10 is connected between the switch SW 3 and the AC-DC power conversion circuit 2; the voltage sensors Sv 8, Sv 9, Sv 10 measure a voltage between the connection line L 31 and the connection line L 32, a voltage between the connection line L 33 and the connection line L 31, and a voltage between the connection line L 33 and the connection line L 31, respectively.<Example of Operation of Control Unit 4 When Battery B> Is ChargedFirst, when the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch, the controller 4 maintains a connection state between the AC-DC power conversion circuit 2 (smoothing capacitor Cs) and the connectors CR, CS, CT, Cn in a disconnected state by the switches SW 3 to SW 7. Here, a connection state in which the AC-DC power conversion circuit 2 and at least three of the four connectors CR, CS, CT, Cn are disconnected from each other is defined as the disconnected state by the switch. For example, in a state illustrated in FIG. 5, although the connector CR is connected to the AC-DC power conversion circuit 2 via the terminal NC of the switch SW 6, the connectors CS, CT, Cn are not connected to the AC-DC power conversion circuit 2 via the switches SW 4 to SW 7, so that the connection state between the AC-DC power conversion circuit 2 and the connectors CR, CN, CT, Cn is regarded as the disconnected state. Specifically, the controller 4 controls the switch SW 3 so that the inductor L 1 is connected to the vehicle compartment power supply section Co. In addition, the controller 4 controls the switches SW 4, SW 5 so that the node between the switching elements Q 17, Q 18 is not connected to the connector Cn and the vehicle compartment power supply section Co. The controller 4 controls the switch SW 6 so that the inductor L 2 is not connected to the connector CS. The controller 4 also controls the switch SW 7 so that the inductor L 3 is not connected to the connector CT.Then, the controller 4 controls the operation of the bidirectional DC-DC power conversion circuit 3 to precharge the smoothing capacitor Cs. Note that stopping the operation of the AC-DC power conversion circuit 2 when the smoothing capacitor Cs is precharged prevents the alternating current output from the AC-DC power conversion circuit 2 from coming to the outside of the vehicle power converter 1 via the vehicle compartment power supply section Co even when the AC-DC power conversion circuit 2 is connected to the vehicle compartment power supply section Co via the switches SW 3, SW 4, SW 5.Subsequently, when the precharge of the smoothing capacitor Cs is completed, the controller 4 controls the switch SW 3 such that the inductor L 1 is connected to the connector CR, controls the switches SW 4, SW 5 such that the node between the switching elements Q 17, Q 18 is not connected to the connector Cn, controls the switch SW 6 such that the inductor L 2 is connected to the connector CS, and controls the switch SW 7 such that the inductor L 3 is connected to the connector CT. This connection state is defined as a connected state when the three-phase alternating current is input.Then, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the three-phase alternating current output from the external power supply device Ch is converted into the direct current corresponding to the target direct current and the direct current is supplied to the battery B.It should be noted that the vehicular power converter 1 in FIG. 4 may also operate with a single-phase alternating current as an input. When the single-phase alternating current is input to the vehicular power converter 1, the connectors CR, Cn only serve as input terminals of the vehicular power converter 1, and a connection state in which the AC-DC power conversion circuit 2 (smoothing capacitor) and at least one of the connectors CR, Cn are separated from each other by the switches SW 3, SW 4, SW 5, SW 6 is defined as a separated state. When the precharge of the smoothing capacitor Cs is completed, the controller 4 controls the switch SW 3 such that the inductor L 1 is connected to the connector CR, controls the switches SW 4, SW 5 such that the node between the switching elements Q 17, Q 18 is connected to the connector Cn, and controls the switch SW 6 such that the inductor L 2 is connected to the connector CR. This connection state is defined as a connected state. In this connection state, an interlace connection is formed with the inductances L1, L2, and each of the switching elements Q13 to Q16 is relieved. In addition, the controller 4 may control the switch SW 6 so that the inductor L 2 is not connected to the connector CR. This connection state is also referred to as a connected state. In this connection state, the inductor L 2 and the switching elements Q 15, Q 16 do not operate.<Example of Operation of Control Unit 4 When Inputted to Vehicle Room Power Supply Section Co>First, when the controller 4 receives a command to power the vehicle compartment power supply section Co sent from the vehicle-side controller Cv, the controller 4 controls the switch SW 3 to connect the inductor L 1 to the vehicle compartment power supply section Co, and controls the switches SW 4, SW 5 to connect the node between the switching elements Q 17, Q 18 to the vehicle compartment power supply section Co.Then, the controller 4 turns on the switching elements Q 13, Q 18 and turns off the switching elements Q 14 to Q 17, and then turns on the switching elements Q 14, Q 17 and turns off the switching elements Q 13, Q 15, Q 16, Q 18. This on-off operation is repeated by the controller 4.<Example of Operation of Control Apparatus 4 when Alternating Current is Outputted from Connectors>When the controller 4 receives the instruction from the user to convert the power supplied from the battery B into AC power and output the AC power to the outside of the vehicle power converter 1 via the connectors CR, Cn, the controller 4 controls the switch SW 3 to connect the inductor L 1 to the connector CR, and controls the switches SW 4, SW 5 to connect the node between the switching elements Q 17, Q 18 to the connector Cn. Then, the controller 4 turns on the switching elements Q 13, Q 18 and turns off the switching elements Q 14 to Q 17, and then turns on the switching elements Q 14, Q 17 and turns off the switching elements Q 13, Q 15, Q 16, Q 18. This on-off operation is repeated by the controller 4.Moreover, when the controller 4 is instructed by the user to convert the current supplied from the battery B into a single-phase three-conductor alternating current and output the single-phase three-conductor alternating current to the outside of the vehicle power converter 1 via CR, CS, Cn, the controller 4 controls the switch SW 3 to connect the inductor L 1 to the connector CR, controls the switches SW 4, SW 5 to connect the node between the switching elements Q 17, Q 18 to the connector Cn, the controller 4 controls the switch SW 3 to connect the inductor L 1 to the connector CR, controls the switches SW 4, SW 5 to connect the node between the switching elements Q 17, Q 5, Q 18 is connected to the connector Cn, and controls the switch SW 6 so that the inductor L 2 is connected to the connector CS. Then, the controller 4 repeatedly turns on and off the switching elements Q 13, Q 14 and the switching elements Q 15, Q 16 alternately to output the AC voltages to each of the connection lines L 31, L 32 that are shifted 180 degrees from each other in phase. In addition, the controller 4 controls the switching elements Q 17, Q 18 such that a voltage measured by the voltage sensor Sv 5 between the connection line L 31 and the connection line L 34 and a voltage measured by the voltage sensor Sv 6 between the connection line L 32 and the connection line L 34 are equal to each other and have opposite signs.The vehicular power converter 1 according to the modified example 2-1 provides the same effects as the first to seventh effects. The vehicular power converter 1 according to the modified example 2-1 also provides the following eighth effect.<Acht Effect>The vehicular power converter 1 according to the modified example 2-1 can process not only the three-phase alternating current but also the single-phase alternating current as an input. Moreover, the vehicular power converter 1 can supply the three-conductor single-phase alternating current.In the modified example 2-1, the switch SW 5 may be omitted, and the switch SW 6 may be made of an electromagnetic relay having a normally closed switch, similar to the switch SW 7.< Example 2-2>FIG. 6 is a diagram of a modified example 2- 2 of the vehicular power converter 1 according to the present embodiment. Note that in FIG. 6, the same components as in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted. In addition, the connector CS is omitted in the vehicle energy converter 1 illustrated in FIG. 6 in comparison with the vehicle energy converter 1 illustrated in FIG. 4. The external power supply device Ch illustrated in FIG. 6 converts a single-phase alternating current from the single-phase alternating current power supply P as an external power supply into a predetermined alternating current, and supplies the predetermined alternating current to the vehicle power converter 1.In the vehicle power converter 1 illustrated in FIG. 6, when the vehicle power converter 1 is connected to the external power supply device Ch via the charging cable Ca, the connector CR is connected to the output terminal OL of the external power supply device Ch via a power line in the charging cable Ca, the connector CT is connected to the output terminal ON of the external power supply device Ch via the other power line in the charging cable Ca, and the connector Cc is connected to the terminal Oc of the external power supply device Ch via the signal line in the charging cable Ca. In this state, a power supply from the external power supply device Ch to the vehicle power converter 1 is ready, and the vehicle power converter 1 and the external power supply device Ch can communicate with each other.The AC-DC power conversion circuit 2 illustrated in FIG. 6 further includes a switch SW 8. The switch SW8 is formed of an electromagnetic relay having a changeover contact. In the switch SW 8, a terminal COM is connected to the node between the switching elements Q 17, Q 18, a terminal NO is connected to the connection line L 33, and a terminal NC is connected to the connection line L 34 via the inductor L 3. That is, the switch SW 8 connects the node between the switching elements Q 17, Q 18 to the connection line L 33 or the connection line L 34.FIG. 7 is a schematic diagram of an example of the switching circuit 5 illustrated in FIG. 6, and it should be noted that in FIG. 7, the same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted.In the switching circuit 5 illustrated in FIG. 7, one terminal of a voltage sensor Sv 11 is connected between the switch SW 6 and the AC-DC power conversion circuit 2, and the other terminal of the voltage sensor Sv 11 is connected between the connector CT and the switch SW 8. The voltage sensor Sv 11 measures a voltage between the connection line L 32 and the connection line L 33. Note that in the switching circuit 5 illustrated in FIG. 7, the switches SW 3, SW 4, SW 7 and the voltage sensors Sv 6, Sv 8, Sv 9, Sv 10 are omitted as compared with the switching circuit 5 illustrated in FIG. 5. Further, in a case where the power is supplied from the single-phase AC power supply P to the vehicle power converter 1, as illustrated in FIG. 6, the switch SW 5 may be omitted.In the switching circuit 5 illustrated in FIG. 7, the terminal COM of the switch SW 5 is connected to the node between the switching elements Q 17, Q 18 via the inductor L 3 and the switch SW 8, and the terminal NO of the switch SW 5 is connected to the connector Cn. Moreover, in the switching circuit 5 illustrated in FIG. 7, the terminal COM of the switch SW 6 is connected to the node between the switching elements Q 15, Q 16 via the inductance L 2, the terminal NC of the switch SW 6 is connected to the connector CR, and the terminal NO of the switch SW 6 is connected to the connector CT. That is, the switch SW 6 connects the node between the switching elements Q 15, Q 16 to the connector CR or the connector CT. Moreover, the switches SW 5, SW 8 connect the node between the switching elements Q 17, Q 18 to the connector CT or the connector Cn, or do not connect the node between the switching elements Q 17, Q 18 to the connector CT and the connector Cn.<Example of Operation of Control Unit 4 When Battery B> Is ChargedFirst, when the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch, the controller 4 maintains a connection state between the AC-DC power conversion circuit 2 (smoothing capacitor Cs) and the connectors CR, CT in a disconnected state by the switches SW 6, SW 8. Here, a connection state in which the AC-DC power conversion circuit 2 and at least one of the two connectors CR, CT are disconnected from each other is defined as the disconnected state by the switches. For example, in a state of FIG. 7, although the connector CR is connected to the AC-DC power conversion circuit 2 through the terminal NC of the switch SW 6, the connector CT is disconnected from the AC-DC power conversion circuit 2 through the switches SW 6, SW 8, so that the connection state between the AC-DC power conversion circuit 2 and the connectors CR, CT is regarded as the disconnected state. Specifically, the controller 4 controls the switch SW 6 so that the node between the switching elements Q 15, Q 16 is connected to the connector CR. In addition, the controller 4 controls the switch SW 8 so that the node between the switching elements Q 17, Q 18 is not connected to the connector CT. Note that the switch SW 5 may be turned on or off.Then, the controller 4 controls the operation of the bidirectional DC-DC power conversion circuit 3 to precharge the smoothing capacitor Cs. Note that stopping the operation of the AC-DC power conversion circuit 2 when the smoothing capacitor Cs is precharged prevents the alternating current output from the AC-DC power conversion circuit 2 from being conducted to the outside of the vehicle power converter 1 via the connectors CR, CT, Cn even when the node between the switching elements Q 17, Q 18 is connected to the connector CT or the connector Cn.Subsequently, when the precharge of the smoothing capacitor Cs is completed, the controller 4 controls the switch SW 6 so as to connect the node between the switching elements Q 15, Q 16 to the connector CR, and controls the switch SW 8 so as to connect the node between the switching elements Q 17, Q 18 to the connector CT. This connection state is defined as a connected state when the single-phase alternating current is input.Subsequently, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the single-phase alternating current output from the external power supply device Ch is converted into the direct current corresponding to the target direct current and the direct current is supplied to the battery B.<Example of Operation of Control Unit 4 when AC power is output from Connectors (during Injection of Single-Phase AC power (when Load Which is Injected is Connected to Connectors CR, CT and Not Connected to Connector Cn)>When the controller 4 instructs the user to convert the direct current supplied from the battery B into a single-phase alternating current and output the single-phase alternating current to the outside of the vehicle power converter 1 via the connectors CR, CT, or the like, the controller 4 controls the switch SW 6 to connect the node between the switching elements Q 15, Q 16 to the connector CR, and controls the switch SW 8 to connect the node between the switching elements Q 17, Q 18 to the connector CT. Then, the controller 4 turns on the switching elements Q 13, Q 15, Q 18 and turns off the switching elements Q 14, Q 16, Q 17, and then turns on the switching elements Q 14, Q 16, Q 17 and turns off the switching elements Q 13, Q 15, Q 18. This on-off operation is repeated by the controller 4. Note that the switch SW 5 may be turned on or off.<Example of Operation of Control Unit 4 in Outputting Alternating Current at Connectors (In Feeding Single-Phase Three-Conductor Alternating Current (When Load to be Fed is Connected to Connectors CR, CT, Cn))>When the controller 4 is instructed to convert the direct current supplied from the battery B into a three-conductor single-conductor alternating current and outputs the three-conductor single-conductor alternating current through the connectors CR, CT, Cn from the user or the like, the controller 4 controls the switch SW 6 so that the node between the switching elements Q 15, Q 16 is connected to the connector CT, and controls the switches SW 5, SW 8 so that the node between the switching elements Q 17, Q 18 is connected to the connector Cn. Then, the controller 4 repeatedly turns on and off the switching elements Q 13, Q 14 and the switching elements Q 15, Q 16 alternately to output the AC voltages in the connection lines L 31, L 33 that are 180 degrees out of phase with each other. In addition, the controller 4 controls the switching elements Q 17, Q 18 such that a voltage measured by the voltage sensor Sv 5 between the connection line L 31 and the connection line L 34 and a voltage measured by the voltage sensor Sv 7 between the connection line L 33 and the connection line L 34 are equal to each other and have opposite signs.<Example of Operation of Control Unit 4 in Determining Whether Switch SW 6 is Locked>When the alternating current is supplied from the alternating current power supply P to the vehicle power converter 1 via the external power supply device Ch and the controller 4 controls the switch SW 6 such that the terminal COM of the switch SW 6 is connected to the terminal NO, the controller 4 compares a differential voltage ΔV between a voltage (peak voltage) measured by the voltage sensor Sv 5 and a voltage (peak voltage) measured by the voltage sensor Sv 7 with a voltage V 11 measured by the voltage sensor Sv 11. The controller 4 determines that the terminal COM and the terminal NC of the switch SW 6 are fused together when the differential voltage ΔV is equal to or substantially equal to the voltage V 11. For example, when the controller 4 controls the switch SW 6 such that the terminal COM of the switch SW 6 is connected to the terminal NO, the controller 4 determines that the terminal COM and the terminal NC of the switch SW 6 are fused together when a difference between the differential voltage ΔV and the voltage V 11 is the voltage threshold Vth 3 or less.The vehicular power converter 1 according to the modified example 2-2 provides the same effects as the first effect to the fifth effect and the eighth effect. The vehicular power converter 1 according to the modified example 2-2 also provides the following ninth effect.< Effect>The vehicular power converter 1 includes the switch SW 6 and the voltage sensors Sv 5, Sv 7, Sv 11. Accordingly, in the case where the alternating current is output from the alternating current power supply P to the vehicle power converter 1 via the external power supply Ch, when controlling the switch SW 6 such that the terminal COM of the switch SW 6 is connected to the terminal NO, the controller 4 compares the differential voltage ΔV with the voltage V 11. The controller 4 determines that the terminal COM and the terminal NC of the switch SW 6 are fused together when the differential voltage ΔV is equal to or substantially equal to the voltage V 11. It is thus possible to determine whether the switch SW 6 is secured.< Example 2-3>FIG. 8 is a diagram of a modified example 2- 3 of the vehicle power converter 1 according to the present embodiment. Note that in FIG. 8, the same components as in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted. The switching circuit 5 illustrated in FIG. 8 corresponds to the switching circuit 5 illustrated in FIG. 7, for example. When the vehicle power converter 1 illustrated in FIG. 8 is connected to the external power supply device Ch via the charging cable Ca, the connector Cn of the vehicle power converter 1 is connected to the terminal n of the external power supply device Ch via the power line in the charging cable Ca. A neutral point of the AC power supply P is connected to the ground and also to the terminal n of the external power supply apparatus Ch.The external power supply device Ch illustrated in FIG. 8 converts the single-phase three-conductor AC output of the AC power supply P as an external power supply into a predetermined AC power, and supplies the predetermined AC power to the vehicle power converter 1.<Example of Operation of Control Unit 4 When Battery B> Is ChargedFirst, when the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch, the controller 4 maintains a connection state between the AC-DC power conversion circuit 2 (smoothing capacitor Cs) and the connectors CR, CT, Cn in a disconnected state by the switches SW 5, SW 6, SW 8. Here, a connection state in which the AC-DC power conversion circuit 2 and at least two of the three connectors CR, CT, Cn are disconnected from each other is defined as a disconnected state by the switch. For example, the controller 4 controls the switch SW 6 so that the node between the switching elements Q 15, Q 16 is connected to the connector CR. In addition, the controller 4 controls the switches SW 5, SW 8 so that the node between the switching elements Q 17, Q 18 is not connected to the connectors CT, Cn.Then, the controller 4 controls the operation of the bidirectional DC-DC power conversion circuit 3 to precharge the smoothing capacitor Cs. Note that stopping the operation of the AC-DC power conversion circuit 2 when the smoothing capacitor Cs is precharged prevents the alternating current output from the AC-DC power conversion circuit 2 from being conducted to the outside of the vehicle power converter 1 via the connectors CR, CT, Cn even when the node between the switching elements Q 17, Q 18 is connected to the connector CT or the connector Cn.Subsequently, when the precharge of the smoothing capacitor Cs is completed, the controller 4 controls the switch SW 6 so as to connect the node between the switching elements Q 15, Q 16 to the connector CR, and controls the switch SW 8 so as to connect the node between the switching elements Q 17, Q 18 to the connector CT. This connection state is defined as a connected state when the single-phase alternating current is input.Subsequently, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the single-phase alternating current output from the external power supply device Ch is converted into the direct current corresponding to the target direct current and the direct current is supplied to the battery B.The example of the operation of the controller 4 when the alternating current (single-phase alternating current or single-phase three-conductor alternating current) is output from the connectors in Modified Example 2-3 is the same as the example of the operation of the controller 4 when the alternating current is output from the connectors in Modified Example 2-2, and therefore the description of the example of the operation is omitted.In addition, whether the switch SW 6 is fused in Modified Example 2- 3 is the same as whether the switch SW 6 is fused in Modified Example 2- 2, so the description of the test is omitted.The vehicular power converter 1 according to the modified example 2-3 provides the same effects as the first to fifth effects, the eighth effect, and the ninth effect.< Example 2-4>FIG. 9 is a diagram of a modified example 2- 4 of the vehicle power converter 1 according to the present embodiment. Note that in FIG. 9, the same components as in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted. The switching circuit 5 shown in FIG. 9 is similar to the switching circuit 5 shown in FIG. 7. In the vehicle power converter 1 illustrated in FIG. 9, when the vehicle power converter 1 is connected to the external power supply device Ch via the charging cable Ca, the connector CR of the vehicle power converter 1 is connected to the terminal R of the external power supply device Ch via the power line in the charging cable Ca, the connector CT of the vehicle power converter 1 is connected to the terminal S of the external power supply device Ch via the power line in the charging cable Ca, the connector Cn of the vehicle power converter 1 is connected to the terminal T of the external power supply device Ch via the power line in the charging cable Ca, and the connector Cc of the vehicle power converter 1 is connected to the terminal Oc of the external power supply device Ch via the signal line in the charging cable Ca.The external power supply device Ch illustrated in FIG. 9 converts the three-phase alternating current output from the alternating current power supply P as an external power supply into a predetermined alternating current, and supplies the predetermined alternating current to the vehicle power converter 1.<Example of Operation of Control Unit 4 When Battery B> Is ChargedFirst, when the controller 4 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch, the controller 4 maintains a connection state between the AC-DC power conversion circuit 2 (smoothing capacitor Cs) and the connectors CR, CT, Cn in a disconnected state by the switches SW 5, SW 6, SW 8. Here, a connection state in which the AC-DC power conversion circuit 2 and at least two of the three connectors CR, CT, Cn are disconnected from each other is defined as a disconnected state by the switch. For example, the controller 4 controls the switch SW 6 so that the node between the switching elements Q 15, Q 16 is connected to the connector CR. In addition, the controller 4 controls the switches SW 5, SW 8 so that the node between the switching elements Q 17, Q 18 is not connected to the connectors CT, Cn.Then, the controller 4 controls the operation of the bidirectional DC-DC power conversion circuit 3 to precharge the smoothing capacitor Cs. Note that stopping the operation of the AC-DC power conversion circuit 2 when the smoothing capacitor Cs is precharged prevents the alternating current output from the AC-DC power conversion circuit 2 from being output to the outside of the vehicle power converter 1 via the connectors CR, CT, Cn even when the node between the switching elements Q 17, Q 18 is connected to the connector CT or the connector Cn.Subsequently, when the precharge of the smoothing capacitor Cs is completed, the controller 4 controls the switch SW 6 such that the node between the switching elements Q 15, Q 16 is connected to the connector CT, and controls the switches SW 5, SW 8 such that the node between the switching elements Q 17, Q 18 is connected to the connector Cn. This connection state is defined as a connected state when the three-phase alternating current is input.Then, the controller 4 controls the operations of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the three-phase alternating current output from the external power supply device Ch is converted into the direct current corresponding to the target direct current and the direct current is supplied to the battery B.The example of the operation of the controller 4 when the alternating current (single-phase alternating current or single-phase three-conductor alternating current) is output from the connectors in Modified Example 2-4 is the same as the example of the operation of the controller 4 when the alternating current is output from the connectors in Modified Example 2-2, and therefore the description of the example of the operation is omitted.In addition, the check as to whether the switch SW 6 is secured in the modified example 2- 4 is the same as the check as to whether the switch SW 6 is secured in the modified example 2- 2, and therefore the description of the check is omitted.The vehicular power converter 1 according to the modified example 2-4 provides the same effects as the first to fifth effects, the eighth effect, and the ninth effect.< Example 3>FIG. 10 is a diagram showing a modified example 3 of the vehicle power converter 1 according to the present embodiment. Note that in FIG. 10, the same components as in FIG. 1 are denoted by the same reference numerals, so their description is omitted.The vehicular power converter 1 illustrated in FIG. 10 is different from the vehicular power converter 1 illustrated in FIG. 1 in that a capacitor Cy 1 is provided as a capacitor for noise reduction between the ground and the connection line L 11 connecting the switch SW 1 to the AC-DC power conversion circuit 2, and a capacitor Cy 2 is provided as a capacitor for noise reduction between the ground and the connection line L 12 connecting the switch SW 2 to the AC-DC power conversion circuit 2. That is, the switches (switches SW 1, SW 2) are provided on all the respective connection lines L 11, L 12 to which the capacitors Cy 1, Cy 2 for reducing the noise are connected. Note that the AC power supply P is two AC power supplies that are 180 degrees out of phase with each other and connected to each other. A zero point of the AC power supply P is connected to the ground, and opposite terminals of the AC power supply P are connected to the external power supply device Ch. That is, the opposite terminals of the three-conductor single-phase AC power supply are connected to the external power supply device Ch. In addition, when the switches SW 1, SW 2 are turned off, the connection line L 11 between the connector CL and the capacitor Cy 1 and the connection line L 12 between the connector CN and the capacitor Cy 2 are each disconnected. In the vehicular power converter 1 illustrated in FIGS. 4 and 8, the capacitors for noise reduction may be provided between the connection line L 31 and ground, between the connection line L 32 and ground, between the connection line L 33 and ground, and between the connection line L 34 and ground. Here, the connection lines L 31, L 32, L 33, L 34 are provided between the switching circuit 5 and the AC-DC power conversion circuit 2.Similarly to the controller 4 illustrated in FIG. 1, the controller 4 illustrated in FIG. 10 also maintains the connection state between the smoothing capacitor Cs and the connectors CL, CN through the switches SW 1, SW 2 in the disconnected state from an end of the previous charging of the battery B to an end of the precharging of the smoothing capacitor Cs. Specifically, in Modified Example 3, both the connection lines L 11, L 12 are turned off by turning off the two switches SW 1, SW 2.The vehicular power converter 1 according to the modified example 3 provides the same effects as the first to sixth effects. The vehicular power converter 1 according to the modified example 3 also provides the following tenth effect.< Effect>The switches SW 1, SW 2 are provided between the AC-DC power conversion circuit 2 and the connectors CL, CN. The capacitors Cy 1, Cy 2 for noise reduction are respectively provided between ground and the connection line L 11 connecting the switch SW 1 to the AC-DC power conversion circuit 2 and between ground and the connection line L 12 connecting the switch SW 2 to the AC-DC power conversion circuit 2. The switches (switches SW 1, SW 2) are provided on all the respective connection lines L 11, L 12 to which the capacitors CY 1, CY 2 for reducing the noise are connected. Accordingly, in a configuration of Modified Example 3, it is possible that all the respective connection lines on which the capacitors for noise reduction are provided are turned off.In a case where the AC power supply P is connected to the ground and only one of the switches SW 1, SW 2 is provided, e.g., the switch SW 2 is not provided, even if the connection state between the smoothing capacitor Cs and the connectors CL, CN is in the disconnected state by turning off the switch SW 1, a loop is formed by the connection line L 12, the capacitor Cy 2, the ground, the AC power supply P, the external power supply device Ch, and the connection line L 12 that generates a reactive current. However, in Modified Example 3, the switches SW 1, SW 2 are turned off to turn off the two connection lines L 11, L 12 on which the capacitors for reducing the noise are provided, thereby suppressing generation of the reactive current. Note that even if the AC power supply P is only one, similarly to FIG. 1, in a case where one of the opposite terminals of the AC power supply P is connected to the ground, the same problem occurs. In this case as well, the vehicular power converter 1 according to the modified example 3 suppresses the reactive current from being generated.< Example 4>FIG. 11 is a diagram showing a modified example 4 of the vehicle power converter 1 according to the present embodiment. Note that in FIG. 11, the same components as in FIG. 1 are denoted by the same reference numerals, so their description is omitted.In the vehicular power converter 1 illustrated in FIG. 11, the switch SW 1 is provided between the connector CL and the smoothing capacitor Cs on the connection line L 21 connecting the AC-DC power conversion circuit 2 to the smoothing capacitor Cs. The switch SW 2 is located between the connector CN and the smoothing capacitor Cs on the connection line L 22 connecting the AC-DC power conversion circuit 2 to the smoothing capacitor Cs. Moreover, the vehicular power converter 1 illustrated in FIG. 11 is different from the vehicular power converter 1 illustrated in FIG. 1 in that the voltage sensor Sv 2 (second voltage sensor) is provided between the connection line L 21 connecting the switch SW 1 to the bidirectional DC-DC power conversion circuit 3 and the connection line L 22 connecting the switch SW 2 to the bidirectional DC-DC power conversion circuit 3. Note that the voltage sensor Sv 3 (first voltage sensor) is provided between the connection line L 21 connecting the AC-DC power conversion circuit 2 to the switch SW 1 and the connection line L 22 connecting the AC-DC power conversion circuit 2 to the switch SW 2.When the controller 4 in FIG. 11 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply device Ch, the controller 4 controls the operation of the bidirectional DC-DC power conversion circuit 3 while maintaining a connection state between the smoothing capacitor Cs and the connectors CL, CN in the disconnected state by the switches SW 1, SW 2, so that the current output from the battery B is supplied to the smoothing capacitor Cs to pre-charge the smoothing capacitor Cs.When the alternating current is output from the external power supply Ch to the vehicle power converter 1 and the connection state between the smoothing capacitor Cs and the connectors CL, CN is maintained in the disconnected state by the switches SW 1, SW 2, the controller 4 illustrated in FIG. 11 determines that at least one of the switches SW 1, SW 2 is fused when the voltage V 3 detected by the voltage sensor Sv 3 corresponds to the voltage threshold Vth 1 (first voltage threshold) or more and the voltage V 2 detected by the voltage sensor Sv 2 corresponds to the voltage threshold Vth 2 (second voltage threshold) or more. It is thus possible to determine whether at least one of the switches SW 1, SW 2 is secured.When the alternating current is output from the alternating current power supply P to the vehicle power converter 1 via the external power supply device Ch and the connection state between the smoothing capacitor Cs and the connectors CL, CN is maintained in the turned-off state by the switches SW 1, SW 2, the controller 4 illustrated in FIG. 11 may be configured such that the controller 4 changes the specific time t (the voltage threshold, the threshold current, the predetermined threshold current in the accumulated current amount) depending on the voltage V 1 detected by the voltage sensor Sv 1. Specifically, the control device 4 can be configured, for example, such that the control device 4 shortens the specific time t as the voltage V 1 decreases. This shortens the time from the electrical connection of the vehicle power converter 1 to the external power supply device Ch until the start of the charging process of the batteries B. In addition, the voltage V 3 detected by the voltage sensor Sv 3 can be used instead of the voltage V 1.The vehicular power converter 1 according to the modified example 4 provides the same effects as the first to fifth effects. The vehicular power converter 1 according to the modified example 4 also provides the following eleventh effect.< Effect>The vehicle power converter 1 includes the switches SW 1, SW 2, the voltage sensor Sv 3, and the voltage sensor Sv 2. Accordingly, when the alternating current is supplied from the alternating current power supply P to the vehicle power converter 1 via the external power supply device Ch and the connection state between the smoothing capacitor Cs and the connectors CL, CN is maintained in the disconnected state by the switches SW 1, SW 2, the controller 4 will determine that at least one of the switches SW 1, SW 2 is fused when the voltage V 3 detected by the voltage sensor Sv 3 is the voltage threshold Vth 1 (first voltage threshold) or more and the voltage V 2 detected by the voltage sensor Sv 2 is the voltage threshold Vth 2 (second voltage threshold) or more. It is thus possible to determine whether at least one of the switches SW 1, SW 2 is secured.< Example 5>FIG. 12 is a diagram showing a modified example 5 of the vehicle power converter 1 according to the present embodiment. Note that in FIG. 12, the same components as in FIG. 1 are denoted by the same reference numerals, and the description of these components is omitted. In the present embodiment, the voltage sensor Sv 1 is an analog sensor, and the controller 4 may determine that an input voltage between the connection lines L 11, L 12 is an AC voltage or a DC voltage by detecting a frequency of the voltage V 1 detected by the voltage sensor Sv 1. In addition, the connectors CL, CN, Cc may be connected to both an AC power supply connector and a DC power supply connector. Moreover, FIG. 12 shows a state in which the vehicular power converter 1 is connected to the external power supply device Ch to which the alternating current from the alternating current power supply P is input. However, a state in which the connectors CL, CN, Cc each have a shape connectable to an external power supply device to which a direct current from a direct current power supply is input and the connectors CL, CN, Cc are connected to such an external power supply device will also be described below.The vehicle power converter 1 illustrated in FIG. 12 further includes switches SW 9, SW 10. The switches SW9, SW10 are each formed by an electromagnetic relay having, for example, a normally-open contact. One terminal of the switch SW 9 is connected to the connector CL, and the other terminal of the switch SW 9 is connected to the positive terminal of the battery B. One terminal of the switch SW 10 is connected to the connector CN, and the other terminal of the switch SW 10 is connected to the negative terminal of the battery B. That is, the switches SW 9, SW 10 each serve as bypass switches for bypassing the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3, and connecting the battery B and the connectors CL, CN.When it is determined that the power supply is an AC power supply based on the voltage V 1 detected by the voltage sensor Sv 1, the controller 4 illustrated in FIG. 12 determines that the vehicle power converter 1 is connected to the AC power supply P via the external power supply Ch, that is, a case where the power consumption at the connectors CL, CN is an AC power. In this case, the controller 4 performs the battery charge preparing operation. While a connection state between the smoothing capacitor Cs and the connector CL, CN is maintained in the disconnected state by turning off at least one of the switches SW 1, SW 2, the smoothing capacitor Cs is precharged. At least one of the switches SW9, SW10 is held in the off state. After the smoothing capacitor Cs is supplied with power from the battery B, the controller 4 causes the connection state between the smoothing capacitor Cs and the connectors CL, CN to transition to the connected state by turning on the switches SW 1, SW 2 and keeping the switches SW 9, SW 10 in the off state, and then the controller 4 controls the operation of each of the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 so that the battery B is charged by the AC power supplied from the external power supply Ch.The following describes the case where the vehicular power converter 1 is connected to the external power supply device to which the direct current from the direct current power supply is input. When it is determined from the voltage V 1 detected by the voltage sensor Sv 1 that the power supply is a DC power supply, the controller 4 determines that the vehicle power converter 1 is connected to the DC power supply, not shown, via the external power supply Ch. That is, this corresponds to a case where the power consumption at the connectors CL, CN is a direct current. In this case, the controller 4 does not execute the battery charge preparing operation. The controller 4 maintains the connection state between the smoothing capacitor Cs and the connectors CL, CN in the disconnected state by the switches SW 1, SW 2, and switches the switches SW 9, SW 10 from off to on, so that the direct current is supplied from the external power supply device Ch to the battery B via the switches SW 9, SW 10. As a result, the battery B is charged.Note that the control device 4 illustrated in FIG. 12 can determine whether the power consumption at the connectors CL, CN is an alternating current or a direct current by performing wired communication with the external power supply device Ch using the signal line in the charging cable Ca and the signal line Lc or by performing wireless communication with the external power supply device Ch. Alternatively, the controller 4 illustrated in FIG. 12 may determine whether the power consumption at the connectors CL, CN is an alternating current or a direct current by using signals transmitted from the vehicle-side controller Cv. As the voltage sensor Sv 1, a DC voltage sensor and an AC voltage sensor may be provided, respectively.In the vehicular power converter 1 illustrated in FIG. 12, as in the vehicular power converter 1 illustrated in FIG. 11, the switches SW 1, SW 2 may be provided on the power lines L 21, L 22 between the AC-DC power conversion circuit 2 and the smoothing capacitor Cs, respectively.When the alternating current is output from the external power supply device Ch to the vehicle power converter 1 and the connection state between the smoothing capacitor Cs and the connectors CL, CN is maintained in the disconnected state by the switches SW 1, SW 2, SW 9, SW 10, the controller 4 illustrated in FIG. 12 may determine that at least one of the switches SW 1, SW 2 is fused when the voltage V 1 detected by the voltage sensor Sv 1 is the voltage threshold Vth 1 (first voltage threshold) or more and the voltage V 2 detected by the voltage sensor Sv 2 is the voltage threshold Vth 2 (second voltage threshold) or more. It is thus possible to determine whether at least one of the switches SW 1, SW 2 is secured. The control device 4 can determine, on the basis of the voltage V 4 detected by the voltage sensor Sv 4, whether at least one of the switches SW 9, SW 10 is fused.In addition, when the alternating current is output from the alternating current power supply P to the vehicle power converter 1 via the external power supply device Ch and the connection state between the smoothing capacitor Cs and the connectors CL, CN is kept disconnected by the switches SW 1, SW 2, SW 9, SW 10, the controller 4 illustrated in FIG. 12 may be configured such that the controller 4 changes the specific time t (the voltage threshold, the threshold current, the predetermined threshold current in the accumulated current amount) depending on the voltage V 1 detected by the voltage sensor Sv 1. Specifically, for example, the controller 4 may be configured such that the controller 4 shortens the predetermined time t as the voltage V 1 decreases. This shortens the time from the electrical connection of the vehicle energy converter 1 to the external power supply device Ch until the beginning of the charging process of the battery B.The vehicular power converter 1 according to the modified example 5 provides the same effects as the first to sixth effects. The vehicular power converter 1 according to the modified example 5 also provides the following twelfth effect.< Effect>When the power consumption at the connectors CL, CN is an alternating current, the controller 4 performs the battery charge preparing operation. When the current consumption at the connectors CL, CN is a direct current, the controller 4 does not execute the battery charge preparing operation and maintains the connection state between the smoothing capacitor Cs and the connectors CL, CN in the turned-off state through the switches SW 1, SW 2. Accordingly, the AC-DC power conversion circuit 2 and the smoothing capacitor Cs are disconnected from the connectors CL, CN even when the direct current is input to the connectors CL, CN, so that there is no problem even when the direct current is input. That is, a dedicated connector for feeding the direct current supplied from the external power supply device Ch does not need to be provided separately from the connectors CL, CN, so that an increase in the manufacturing cost of the vehicular power converter 1 is suppressed. In addition, when the current supplied from the external power supply device Ch is a direct current, the smoothing capacitor Cs does not need to be precharged, so that an unnecessary battery charge preparing operation is omitted.The present invention is not limited to the above-described embodiment, and may be modified within the scope of the present invention.The vehicular power converter 1 can be directly connected to the AC power supply P without the external power supply device Ch. Specifically, in Modified Example 5, the vehicular power converter 1 can be directly connected to the DC power supply without the external power supply device Ch.The terminal NO and the terminal NC of the electromagnetic relay with the changeover contact may be interchanged. The electromagnetic relay with the normally open contact can be replaced by an electromagnetic relay with an normally open contact. In this case, when the control signals are not input to each switch, the terminal COM of each switch is connected to the terminal NC. However, when each switch is not in the power-off state in this state, it is necessary to set each switch to the power-off state by switching each switch from the terminal NC to the terminal NO in advance before the controller 4 determines that the vehicle power converter 1 is connected to an external power supply. The control device 4 then only needs to input the control signals for each switch as required.When there is no need to output the alternating current from the battery B side to the connector or the vehicle compartment power supply section Co, the configuration of the AC-DC power conversion circuit 2 is not limited to the configuration of the circuit illustrated in FIGS. 2A, 4, and 6 as long as an input alternating current to the AC-DC power conversion circuit 2 is at least rectified. For example, the AC-DC power conversion circuit 2 may include a diode rectifier circuit on one side of the connectors. Here, a positive output terminal of the diode rectifier circuit may be connected to the one terminal of the inductor L, and a negative output terminal of the diode rectifier circuit may be connected to the source terminal of the switching element Q 2, and the phase including the switching elements Q 3, Q 4 may be omitted, so that the AC-DC power conversion circuit 2 may have only the phase including the switching elements Q 1, Q 2. In addition, when the power factor of the AC-DC power conversion circuit 2 does not need to be corrected, the AC-DC power conversion circuit 2 may be composed of only the diode rectifier circuit.When the vehicular power converter 1 is treated as the input with the three-phase alternating current as in the modified example 2- 1 and the connector Cn is omitted, a connection state in which the AC-DC power conversion circuit 2 and at least two of the three connectors CR, CS, CT are disconnected from each other may be defined as a disconnected state.In Modified Example 2-1, the switch SW 5 may be omitted. In addition, the vehicle compartment power supply section Co can be omitted, and the electromagnetic relay having the normally open contact or the electromagnetic relay having the normally open contact can be used as the switch SW 3, SW 4.In Modified Example 3 and Modified Example 5, the switches SW 1, SW 2 may be replaced with the switches SW 3, SW 4, and the vehicle compartment power supply section Co may be provided as in Modified Example 1.The noise reduction capacitors according to Modified Example 3 may be applied to the three-phase alternating current circuit according to Modified Example 2-1 or the single-phase three-conductor alternating current circuit according to Modified Example 2-3.The bypass passage that bypasses the AC-DC power conversion circuit 2 and the bidirectional DC-DC power conversion circuit 3 and connects the connectors CL, CN to the battery B via the switches SW 9, SW 10 is provided in the vehicle power converter 1 in the modified example 5. However, the bypass passage may be provided outside the vehicle power converter 1. In addition, a desired power converter, a relay, a capacitor or the like may be provided in the bypass passage.The control of feeding the alternating current to the connectors and the control of feeding the direct current to the connector in Modified Example 5 can be applied to Modified Example 2-1 or Modified Example 2-4 that treat the three-phase alternating current as an input.The features of the above-described embodiment will be summarized below.(Supplementary Note 1)A vehicle energy converter mounted on a vehicle, the vehicle energy converter comprising:connectors to which a power output from an external power supply is input;an AC-DC power conversion circuit that, when the power consumption at the connectors is an AC current, converts the AC current into a DC current by rectifying the AC current;a smoothing capacitor that smoothes the direct current rectified by the AC-DC power conversion circuit;a bidirectional DC-DC power conversion circuit that converts the direct current smoothed by the smoothing capacitor into a direct current corresponding to a target direct current and supplies the direct current to a vehicle-mounted battery;a switch provided between the smoothing capacitor and at least one of the connectors; anda controller that controls respective operations of the AC-DC power conversion circuit, the bidirectional DC-DC power conversion circuit, and the switch, characterized in thatthe controller performs a battery charge preparation operation when the controller determines that the vehicle power converter is connected to the external power supply, andIn the battery charge preparation operation, after the controller controls the operation of the bidirectional DC-DC power conversion circuit while holding a connection state between the smoothing capacitor and the connectors by the switch in a disconnected state so that a current output from the battery is supplied to the smoothing capacitor, the controller causes a connection state of the switch to transition from a disconnected state to a connected state.(Supplementary Note 2)The vehicular power converter according to Supplementary Note 1, characterized in that in the battery charge preparation operation, when a certain time has elapsed since the start of the power supply from the battery to the smoothing capacitor, the controller causes the connection state of the switch to transition from the disconnected state to the connected state, the certain time is equal to or longer than a time required for a voltage across the smoothing capacitor to reach such a voltage that a current flowing from the AC-DC power conversion circuit to the smoothing capacitor when the connection state of the switch transitions to the connected state is equal to or less than an allowable current of the smoothing capacitor, and the certain time is equal to or shorter than the time required, in order that the voltage across the smoothing capacitor reaches a peak voltage of the alternating current supplied from the external power supply or a voltage of the direct current supplied from the AC-DC power conversion circuit.(Supplementary Note 3)The vehicular power converter according to Supplementary Note 1 or 2, further comprising a vehicle compartment power supply section from which an alternating current is input to a vehicle compartment, characterized in that the AC-DC power conversion circuit is a bidirectional circuit that converts a direct current on a side of the smoothing capacitor into an alternating current and outputs the alternating current toward the connectors, the switch is provided between the AC-DC power conversion circuit and at least one of the connectors, and the switch connects the AC-DC power conversion circuit to the connectors or connects the AC-DC power conversion circuit to the vehicle compartment power supply section.(Supplementary Note 4)The vehicle power converter according to any one of Additional Notes 1 to 3, further comprising:a first voltage sensor disposed between the connectors and the switch, the switch being provided between the AC-DC power conversion circuit and at least one of the connectors; anda second voltage sensor provided between the AC-DC power conversion circuit and the switch, characterized in thatwhen the controller maintains the connection state between the smoothing capacitor and the connectors through the switch in the disconnected state, the controller determines that the switch is fused in a case where a first voltage detected by the first voltage sensor is a first voltage threshold value or more and a second voltage detected by the second voltage sensor is a second voltage threshold value or more.(Supplementary Note 5)The vehicle power converter according to any one of Additional Notes 1 to 3, further comprising:a first voltage sensor provided between the AC-DC power conversion circuit and the switch, the switch being provided between the AC-DC power conversion circuit and the smoothing capacitor; anda second voltage sensor provided between the bidirectional DC-DC power conversion circuit and the switch, characterized in thatwhen the controller maintains the connection state between the smoothing capacitor and the connectors through the switch in the disconnected state, the controller determines that the switch is fused in a case where a first voltage detected by the first voltage sensor is a first voltage threshold value or more and a second voltage detected by the second voltage sensor is a second voltage threshold value or more.(Supplementary Note 6)The vehicle power converter according to Supplementary Note 2, further comprisinga voltage sensor provided between the connectors and the switch, characterized in thatthe controller shortens the predetermined time when a voltage detected by the voltage sensor decreases.(Supplementary Note 7)The vehicle energy converter according to any one of the supplementary comments 1 to 4 and the supplementary comment 6, characterized in thatthe switch comprises a plurality of switches,the switches are provided between the AC-DC power conversion circuit and the connectors,the vehicle power converter includes capacitors provided between ground and corresponding connection lines connecting the switches to the AC-DC power conversion circuit; andthe switches are provided on all the respective connecting lines to which the capacitors are connected.(Supplementary Note 8)The vehicle energy converter according to any one of the supplements 1 to 7, characterized in thatwhen the current consumption at the connectors is an alternating current, the control device performs the battery charge preparation operation, andwhen the power consumption at the connectors is a direct current, the controller does not execute the battery charge preparing operation and maintains the connection state of the switch in the disconnected state.Vehicle energy converter (1) according to one of Claims 1 to 7, characterized in thatwhen the current consumption at the connectors is an alternating current, the control device (4) performs the battery charge preparation operation, andwhen the power consumption at the connectors is a direct current, the controller (4) does not execute the battery charge preparing operation and maintains the connection state of the switch in the disconnected state.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2022-054686

[0002]

Claims

A vehicular power converter (1) mounted on a vehicle (Ve), the vehicular power converter (1) including: connectors to which a power output from an external power supply (P) is input; an AC-DC power conversion circuit (2) that, when the power input to the connector is an AC power, converts the AC power into a DC power by rectifying the AC power; a smoothing capacitor (Cs) that smoothes the DC power rectified by the AC-DC power conversion circuit (2); a bidirectional DC-DC power conversion circuit (3) that converts the DC power smoothed by the smoothing capacitor (Cs) into a DC power corresponding to a target DC power, and supplies the DC power to a battery (B) mounted on the vehicle (Ve); a switch provided between the smoothing capacitor (Cs) and at least one of the connectors; and a controller (4) that controls respective operations of the AC-DC power conversion circuit (2), the bidirectional DC-DC power conversion circuit (3), and the switch, characterized in that the controller (4) performs a battery charge preparation operation when the controller (4) determines that the vehicle power converter (1) is connected to the external power supply (P), and in the battery charge preparation operation after the controller (4) controls operation of the bidirectional DC-DC power conversion circuit (3) while a connection state between the smoothing capacitor (Cs) and the connectors is maintained in a disconnected state by the switch, So that a current output from the battery (B) is supplied to the smoothing capacitor (Cs), the controller (4) causes a connection state of the switch to transition from a disconnected state to a connected state.The vehicular power converter (1) according to claim 1, characterized in that in the battery charge preparation operation, when a certain time (t) has elapsed since the start of the power supply from the battery (B) to the smoothing capacitor (Cs), the controller (4) causes the connection state of the switch to transition from the disconnected state to the connected state, the certain time (t) is equal to or longer than a time required for a voltage across the smoothing capacitor (Cs) to reach a voltage such that a current flowing from the AC-DC power conversion circuit (2) to the smoothing capacitor (Cs) when the connection state of the switch transitions to the connected state is equal to or less than an allowable current of the smoothing capacitor (Cs), and the specified time (t) is equal to or shorter than a time required for the voltage across the smoothing capacitor (Cs) to reach a peak voltage of the alternating current input from the external power supply (P) or a voltage of the direct current supplied from the AC-DC power conversion circuit (2).The vehicle power converter (1) according to claim 1 or 2, further comprising: a vehicle compartment power supply section (Co) from which an alternating current is input to a vehicle compartment, characterized in that the AC-DC power conversion circuit (2) is a bidirectional circuit that converts a direct current on a side of the smoothing capacitor (Cs) into an alternating current and outputs the alternating current to the connectors, the switch is provided between the AC-DC power conversion circuit (2) and the at least one of the connectors, and the switch connects the AC-DC power conversion circuit (2) to the connectors or connects the AC-DC power conversion circuit (2) to the vehicle compartment power supply section (Co).The vehicle power converter (1) according to any one of claims 1 to 3, further comprising: a first voltage sensor (Sv1) disposed between the connectors and the switch, the switch being disposed between the AC-DC power conversion circuit (2) and the at least one of the connectors; and a second voltage sensor (Sv2) provided between the AC-DC power conversion circuit (2) and the switch, characterized in that when the controller (4) maintains the connection state between the smoothing capacitor (Cs) and the connectors through the switch in the disconnected state, the controller (4) determines that the switch is fused in a case where a first voltage (V1) detected by the first voltage sensor (Sv1) is a first voltage threshold (Vth1) or more and a second voltage (V2) detected by the second voltage sensor (Sv2) is a second voltage threshold (Vth2) or more.The vehicular power converter (1) according to any one of claims 1 to 3, further including: a first voltage sensor (Sv3) provided between the AC-DC power conversion circuit (2) and the switch, the switch being provided between the AC-DC power conversion circuit (2) and the smoothing capacitor (Cs); and a second voltage sensor (Sv2) provided between the bidirectional DC-DC power conversion circuit (3) and the switch, characterized in that when the controller (4) maintains the connection state between the smoothing capacitor (Cs) and the connectors through the switch in the disconnected state, the controller (4) determines that the switch is fused in a case where a first voltage (V3) detected by the first voltage sensor (Sv3) is a first voltage threshold (Vth1) or more and a second voltage (V2) detected by the second voltage sensor (Sv2) is a second voltage threshold (Vth2) or more.The vehicular power converter (1) according to claim 2, further comprising: a voltage sensor (V1) provided between the connectors and the switch, characterized in that the controller (4) shortens the predetermined time (t) when a voltage (V1) detected by the voltage sensor (V1) decreases.The vehicular power converter (1) according to any one of claims 1 to 4 and claim 6, characterized in that the switch includes a plurality of switches, the switches are provided between the AC-DC power conversion circuit (2) and the connectors, the vehicular power converter (1) includes capacitors (Cy1, Cy2) provided between a ground and corresponding connection lines connecting the switches to the AC-DC power conversion circuit (2), and the switches are provided on all the corresponding connection lines to which the capacitors (Cy1, Cy2) are connected.The vehicular power converter (1) according to any one of claims 1 to 7, characterized in that when the power consumption at the connectors is an alternating current, the controller (4) performs the battery charge preparing operation, and when the power consumption at the connectors is a direct current, the controller (4) does not perform the battery charge preparing operation and maintains the connection state of the switch in the disconnected state.

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