On-vehicle charger

Abstract

To construct an on-vehicle charger that charges a DC power supply of a vehicle driving device having a rotary electric machine, an inverter, and the DC power supply by using a coil of the rotary electric machine and the inverter with a power from an external AC power supply by suppressing an increase of a system cost.SOLUTION: An on-vehicle charger 10 that charges a DC power supply 3 of a vehicle driving device having a winding magnetic field type rotary electric machine 70, an inverter 5, an exciting circuit 50, and a DC power supply 3 by a power supplied from an external AC power supply 4, is constructed so as to contain the exciting circuit 50, and comprises: a first circuit 1 that converts a power between an AC power and a first DC power on the side of the external AC power supply 4; the inverter 5; a stator coil 7 with a plurality of phases; and an output capacitor Cs, and comprises a second circuit 2 that generates a second DC power for charging the DC power supply 3 from the first DC power. The output capacitor Cs is connected to between a neutral point 7N of the stator coil 7 and a DC negative electrode.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an on-board charging device. [Background technology]

[0002] JP2022-503713A discloses an onboard charging device (onboard charger) that charges a DC power source mounted on a vehicle equipped with a rotating electric machine as a driving force source for wheels such as an electric vehicle or a hybrid vehicle while the vehicle is mounted on the vehicle (the symbols in parentheses in the background art are those of the referenced document). FIG. 3 of this document illustrates an onboard charging device in which a single-phase external AC power source (310) is connected to the neutral point of a Y-connected three-phase coil, each of the three-phase coils is connected to each of the AC side arms of an inverter (220), an input side terminal of a DC / DC converter is connected to a DC side terminal of the inverter (220), and a DC power source is connected to an output side terminal of the DC / DC converter. The three-phase coils and the inverter (220) form an AC / DC converter that converts a sine wave grid current from the external AC power source (310) into DC. By controlling the switching of the inverter (220), the AC-DC converter also functions as a power factor correction (PFC) circuit that improves the power factor of the DC power converted from the AC power. A ripple occurs in the current after the AC-DC conversion, the frequency of which is twice the frequency (system frequency) of the external AC power source (310). The DC-DC converter reduces the ripple and generates a battery current for charging the DC power source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-503713 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, for example, in an on-board charging device for an electric vehicle or a hybrid vehicle, a coil (stator coil) provided in a stator of a rotating electric machine that is a driving force source in the vehicle can be used as the three-phase coil. However, such a rotating electric machine is designed to have a high power density and has a small inductance. As illustrated in FIG. 3 of the above document, when a single-phase external AC power supply is connected to the neutral point to form an AC-DC converter, the peak value of the harmonic current of the system current of the external AC power supply tends to be large during AC-DC conversion.

[0005] As one method for suppressing this, it is possible to increase the control frequency of the inverter constituting the AC-DC converter. Alternatively, it is possible to increase the control frequency of the DC-DC converter in order to reduce ripples on the DC-DC converter side. However, when the control frequency is increased, it is necessary to shorten the control period (operating frequency) of the control device that controls the inverter and the DC-DC converter. In addition, switching at a high frequency due to a fast control period increases the loss in the switching elements provided in the inverter and the DC-DC converter, leading to a decrease in the efficiency of the vehicle-mounted charging device. In addition, it becomes necessary to use a microcomputer or the like capable of high-speed operation as the control device, which leads to an increase in the cost of the vehicle-mounted charging device. Alternatively, as another method, it is possible to add an inductor between the external AC power source and the neutral point of the coils of the multiple phases. However, in this case, the addition of the inductor also increases the cost of the vehicle-mounted charging device.

[0006] In view of the above, it is desirable to configure an on-board charging device that charges the DC power supply of a vehicle drive device that has a rotating electric machine, an inverter, and a DC power supply using the coil of the rotating electric machine and the inverter with power from an external AC power supply, while suppressing increases in system costs. [Means for solving the problem]

[0007] In view of the above, an on-board charging device is an on-board charging device that charges the DC power supply of a vehicle drive device with power supplied from an external AC power supply, the on-board charging device including: a stator having multiple-phase stator coils connected to each other at a neutral point; and a rotor having a field winding that generates a field magnetic flux, the stator having a wound-field type rotating electric machine that serves as a driving force source for wheels; a DC power supply; an inverter connected between the stator coil and the DC power supply and converting power between DC and multiple-phase AC; and an excitation circuit connected between the field winding and the DC power supply and exciting the field winding. The on-board charging device includes: a first circuit that includes the excitation circuit and converts power between AC power on the side of the external AC power supply and a first DC power; and a second circuit that includes the inverter, the multiple-phase stator coils, and an output capacitor and generates second DC power from the first DC power to charge the DC power supply, the output capacitor being connected between the neutral point of the stator coil and a negative pole of DC.

[0008] According to this configuration, the first circuit is configured using an excitation circuit, and the first circuit is configured using an inverter and a stator coil, so that the in-vehicle charging device can be configured with a simplified structure compared to a case where a separate circuit for charging the DC power source is provided. In addition, among the circuits configuring the in-vehicle charging device, a circuit that converts power between AC power on the external AC power source side and the first DC power is required to have an appropriate inductance. Although it is possible to use a coil of a rotating electric machine as an inductor, a rotating electric machine is designed to have a high power density, and the inductance of the coil is generally small. According to this configuration, the first circuit, which requires an appropriate inductance to convert power between AC power and the first DC power, is configured without using a coil of the rotating electric machine. Therefore, the first circuit can be configured while ensuring sufficient performance for AC-DC conversion, such as a power factor correction function. In addition, the cost of the in-vehicle charging device can be reduced by configuring the second circuit, which does not require high inductance, using a drive circuit of the rotating electric machine. Furthermore, since an appropriate inductance can be set in the AC-DC converter, even if the first circuit is a switching power supply circuit, there is no need to control the first circuit with a short control period (high control frequency), and loss in the switching elements constituting the first circuit can be easily reduced. Thus, according to this configuration, it is possible to configure an on-board charging device that charges the DC power supply of a vehicle drive device including a rotating electric machine, an inverter, and a DC power supply with power from an external AC power supply by utilizing the coil of the rotating electric machine and the inverter, while suppressing an increase in system costs.

[0009] Further features and advantages of the on-board charging device will become apparent from the following description of exemplary and non-limiting embodiments which are given with reference to the drawings. [Brief description of the drawings]

[0010] [Figure 1] Schematic circuit block diagram of a drive control system for a rotating electric machine [Diagram 2] A circuit block diagram showing a first example of an in-vehicle charging device. [Diagram 3] A circuit block diagram showing a second example of an in-vehicle charging device. [Figure 4] A circuit block diagram showing a third example of an in-vehicle charging device. [Diagram 5] A circuit block diagram showing a fourth example of an in-vehicle charging device. [Figure 6] A functional block diagram obtained by modifying the circuit block diagrams shown in FIGS. 4 and 5. [Figure 7] Circuit block diagram showing a comparative example of an in-vehicle charging device DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the vehicle-mounted charging device will be described with reference to the drawings. The circuit block diagram of FIG. 1 shows a schematic diagram of a drive control system of a rotating electric machine 70, and the circuit block diagrams of FIG. 2 to FIG. 5 show an example of a vehicle-mounted charging device 10 using the drive control system of the rotating electric machine 70. The vehicle-mounted charging device 10 is a device that charges a DC power source 3 provided in a vehicle drive device 9 as shown in FIG. 1 while being mounted on a vehicle. As shown in FIG. 1, the vehicle drive device 9 of this embodiment includes a rotating electric machine 70 that serves as a drive power source for wheels of a hybrid vehicle, an electric vehicle, or the like, an inverter 5 that converts power between DC and multiple-phase AC (here, three phases), and a DC power source 3 connected to the inverter 5. Note that this does not prevent the vehicle drive device 9 from including other drive power sources such as an internal combustion engine (not shown) in addition to the rotating electric machine 70.

[0012] 2 to 5, the vehicle-mounted charging device 10 is a device that charges a DC power source 3 of a vehicle drive device 9 with power supplied from an external AC power source 4 (grid power source, single-phase in this case), and is a device that is so-called an onboard charger. In this embodiment, the vehicle-mounted charging device 10 is configured to share some components with the vehicle drive device 9. Specifically, the inverter 5, the coil 7 (stator coil) of the rotating electric machine 70, and the excitation circuit 50 are shared.

[0013] As shown in FIG. 1, a vehicle drive device 9 includes a control device 8 that controls a rotating electric machine 70 that serves as a driving force source for a vehicle, and the control device 8 drives and controls the rotating electric machine 70 by performing current feedback control. The rotating electric machine 70 to be driven is a wound field type synchronous rotating electric machine (EESM: Electrically Excited Synchronous Motor) having a stator 71 in which a multi-phase (N phases, where N is an arbitrary natural number; in this embodiment, a three-phase form with N=3 is illustrated) coil 7 (stator coil) is arranged on a stator core, and a wound field type rotor 72. The wound field type synchronous rotating electric machine has a rotor structure equipped with an electromagnet using a field winding 7r instead of a permanent magnet as a field source. The field magnetic flux by the electromagnet can be adjusted by a field current supplied to the field winding 7r from an excitation circuit 50 controlled by the control device 8. The excitation circuit 50 is configured with switching elements, and adjusts (transforms) the DC voltage supplied from the DC power supply 3 and applies it to the field winding 7r. A wound-field type synchronous rotating electric machine has the following advantages over a permanent magnet type rotating electric machine (PMSM: Permanent Magnet Synchronous Motor): (1) since the field flux is variable, efficiency can be improved in the operating range of medium to high speed and low torque, and the constant output range can be expanded, and (2) it is not affected by the unstable supply of permanent magnets using rare earths, etc. For this reason, in recent years, it has also been increasingly used as a driving force source for the wheels of electric vehicles and hybrid vehicles.

[0014] As described above, the wound-field type synchronous rotating electric machine generates a field in the rotor 72 by passing a field current through the field winding 7r of the rotor 72. However, since the rotor 72 rotates, it is necessary to provide a structure for passing a field current in the same direction through the field winding 7r. FIG. 1 illustrates a structure provided with a brush 73, which is a mechanical switching structure. The rotating electric machine 70 of FIG. 2 and FIG. 4, which will be referred to later, also has a structure provided with a brush 73. Note that, as in the rotating electric machine 70 of FIG. 3 and FIG. 5, which will be referred to later, a driving circuit 74 may be provided instead of the brush 73 to electrically change the direction of the field current (brushless EESM). The driving circuit 74 is configured to include, for example, a rotary transformer 75 and a rectifier circuit 76. The structure of such a wound-field type synchronous rotating electric machine is publicly known, so a detailed description thereof will be omitted.

[0015] In this embodiment, the stator 71 is illustrated as being in a Y-type (star type) configuration in which three-phase coils 7 are short-circuited at a neutral point 7N. However, the rotating electric machine 70 may be in a configuration in which, for example, two sets of three-phase coils 7 are provided and the rotating electric machine 70 is driven by six-phase alternating current. The rotating electric machine 70 can function as both an electric motor and a generator. When the rotating electric machine 70 functions as an electric motor, the rotating electric machine 70 is in a power running state, and when the rotating electric machine 70 functions as a generator, the rotating electric machine 70 is in a regenerative state.

[0016] As shown in FIG. 1, the vehicle drive device 9 includes an inverter 5. The inverter 5 is connected to an AC rotating electric machine 70 and a DC power source 3, and converts power between multiple phase AC and DC. A pair of DC side terminals (DC side terminals T5d) of the inverter 5 are connected to both positive and negative terminals of the DC power source 3. Specifically, the positive terminal (inverter positive terminal T5P) of the pair of DC side terminals T5d is connected to the positive electrode of the DC power source 3, and the negative terminal (inverter negative terminal T5N) of the pair of DC side terminals T5d is connected to the negative electrode of the DC power source 3. The multiple phase AC side terminals of the inverter 5 are connected to the multiple phase coils 7, respectively. In this embodiment, the inverter 5 includes a U-phase arm, a V-phase arm, and a W-phase arm as multiple phase arms. Each arm is formed by connecting in series an upper stage switching element 5U arranged on the positive side and a lower stage switching element 5L arranged on the negative side. The midpoint of each arm, i.e., the connection point between the upper-stage switching element 5U and the lower-stage switching element 5L, is connected to the respective coil 7. Specifically, the midpoint of the U-phase arm is connected to the U-phase coil 7u, the midpoint of the V-phase arm is connected to the V-phase coil 7v, and the midpoint of the W-phase arm is connected to the W-phase coil 7w.

[0017] A smoothing capacitor (DC link capacitor 6) that smoothes the voltage between the positive and negative poles (DC link voltage Vdc) is provided on the DC side of the inverter 5. In addition, a voltage sensor (DC link voltage sensor 61) that detects the DC link voltage Vdc is also provided on the DC side of the inverter 5.

[0018] The DC power source 3 is, for example, a rechargeable secondary battery (battery) such as a lithium ion battery, an electric double layer capacitor, or the like. When the rotating electric machine 70 is the driving force source of the vehicle as in this embodiment, the DC power source 3 is a high-voltage, large-capacity DC power source, and the rated power supply voltage is, for example, 200 to 400 [V]. In many cases, the DC power source 3 is configured to be capable of electrically connecting and disconnecting the inverter 5 and the rotating electric machine 70 by operating a main switch (ignition switch) of the vehicle, or the like. For example, the DC power source 3 is connected to the inverter 5 and the rotating electric machine 70 via a main contactor 11 (first contactor) configured by a relay or the like. The DC power source 3 is also provided with a current sensor (battery current sensor 31) that detects an input / output current (battery current Ibat: see FIG. 6) for the DC power source 3, and a voltage sensor (battery voltage sensor 32) that detects a terminal voltage (battery voltage Vbat: see FIG. 6) of the DC power source 3.

[0019] Although not shown in the figure, for example, when the DC power supply 3 is a lithium ion battery, a battery management system (BMS) is often provided. A secondary battery such as a lithium ion battery is composed of a plurality of cells (battery cells). The battery management system is a battery management control system that performs the following: (1) prevention of overcharging and overdischarging of cells, (2) prevention of overcurrent flowing through cells, (3) cell temperature management, (4) calculation of the state of charge (SOC), (5) equalization of cell voltages, etc. The battery current sensor 31 and battery voltage sensor 32 described above may be configured as part of the battery management system.

[0020] As shown in FIG. 1, the inverter 5 is configured to have a plurality of switching elements 5S. It is preferable to apply a power semiconductor element capable of operating at high frequencies, such as an IGBT (Insulated Gate Bipolar Transistor), a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a SiC-MOSFET (Silicon Carbide-Metal Oxide Semiconductor FET), a SiC-SIT (SiC-Static Induction Transistor), or a GaN-MOSFET (Gallium Nitride-MOSFET), to the switching elements 5S. In this embodiment, a FET is used as the switching element 5S. In this embodiment, a freewheel diode is connected in parallel to each switching element 5S with the forward direction being the direction from the negative electrode to the positive electrode (the direction from the lower stage to the upper stage). Of course, in the case of using a body diode or in the case of using reverse conduction in a transistor of a wide band gap semiconductor made of enhancement mode gallium nitride (E-GaN), such a freewheel diode may not be provided.

[0021] As shown in FIG. 1, the inverter 5 is controlled by a control device 8. The control device 8 is constructed with a logic circuit such as a microcomputer as a core member. For example, the control device 8 performs current feedback control using a vector control method based on a target torque (torque command) of the rotating electric machine 70 provided as a request signal from another control device such as a vehicle control device 90, which is one of the higher-level control devices, to drive the rotating electric machine 70 via the inverter 5. In the vector control method, feedback control is performed by converting the currents (U-phase current Iu, V-phase current Iv, and W-phase current Iw in this embodiment: see FIG. 6, etc.) flowing through the coils 7 of each phase into vector components of a d-axis, which is the direction of the magnetic field generated by the rotor 72, and a q-axis, which is a direction perpendicular to the d-axis (a direction leading an electrical angle of π / 2 with respect to the direction of the magnetic field). The coordinate system after the coordinate conversion is called a dq-axis orthogonal coordinate system. The operating voltage of logic circuit elements such as a microcomputer is about 3.3 to 5 volts. In this embodiment, for simplification, the control signal generated by the logic circuit element is transmitted to the inverter 5 via a drive circuit (not shown). Alternatively, the control device 8 may be considered to include the drive circuit.

[0022] The actual current flowing through the coils 7 of each phase of the rotating electric machine 70 is detected by a current sensor (motor current sensor 81), and the control device 8 acquires the detection results. In addition, the rotational position and rotational speed (angular velocity) of the rotor 72 of the rotating electric machine 70 at each point in time are detected by a rotation sensor 82 such as a resolver or an inductive position sensor, and the control device 8 acquires the detection results. The control device 8 executes current feedback control using the detection results of the motor current sensor 81 and the rotation sensor 82. The control device 8 is configured to have various functional units for current feedback control, and each functional unit is realized by cooperation between hardware such as a microcomputer and software (programs).

[0023] As described above, the rotating electric machine 70 connected to the DC power source 3 via the inverter 5 functions as an electric motor by the power supplied from the DC power source 3, and can also function as a generator to charge the DC power source 3. For example, in a hybrid vehicle, mechanical energy can be supplied to the rotating electric machine 70 by the power of an internal combustion engine or the like to cause the rotating electric machine 70 to generate electricity, but there are cases where the DC power source 3 cannot be sufficiently charged because there are few opportunities for power generation. Also, in an electric vehicle equipped with only the rotating electric machine 70 as a driving force source, power generation is limited to mechanical energy from the wheels during inertial running, and the DC power source 3 cannot be sufficiently charged in many cases. Also, in a hybrid vehicle, there are cases where it is more energy efficient to supply power from an external source than to have the rotating electric machine 70 generate electricity. For this reason, it is preferable that the DC power source 3 be configured to be charged by an external power source when the DC power source 3 is mounted on the vehicle.

[0024] The vehicle-mounted charging device 10 of this embodiment charges a DC power source 3 of a vehicle drive device 9 with power supplied from an external AC power source 4. As shown in FIG. 2 to FIG. 5, the vehicle-mounted charging device 10 includes a first circuit 1 that is connected to the external AC power source 4 and converts the AC power from the external AC power source 4 into a first DC power, and a second circuit 2 that generates a second DC power from the first DC power to charge the DC power source 3. The first circuit 1 includes an excitation circuit 50. The second circuit 2 includes an inverter 5, a multi-phase coil 7, and an output capacitor Cs. The output capacitor Cs is connected between a neutral point 7N of the coil 7 and a negative pole of the DC. As will be described later, the first circuit 1 is an AC-DC converter (AC / DC converter), and the second circuit 2 is a DC-DC converter (DC / DC converter) or an active decoupling circuit.

[0025] The first circuit 1 (AC-DC converter) and the second circuit 2 (DC-DC converter or active decoupling circuit) are configured with switching elements (switching elements indicated by symbols 1S and 5S), and these switching elements are controlled by a control device 8 that drives and controls a rotating electric machine 70 via an inverter 5. As described later, the vehicle-mounted charging device 10 is configured with contactors (main contactor 11, OBC contactor 12 (second contactor), grid contactor 13, and excitation contactor 14 (third contactor)). These contactors are configured by relays, for example, and these contactors are also controlled by the control device 8, or the control device 8 and the vehicle control device 90. As described above with reference to FIG. 1, the control device 8 is included in the drive control system of the rotating electric machine, and the control device 8 is also used in common for drive control of the rotating electric machine 70 and charge control of the DC power source 3.

[0026] When charging the DC power source 3, power is supplied from the external AC power source 4 to the DC power source 3. Therefore, in terms of circuit configuration, the first circuit 1 (AC-DC converter) arranged relatively closer to the external AC power source 4 (upstream side) may be called a front-end circuit, and the second circuit 2 (DC-DC converter or active decoupling circuit) arranged relatively closer to the DC power source 3 (downstream side) may be called a back-end circuit. In this embodiment, the first circuit 1 (AC-DC converter) which is a front-end circuit connected to the external AC power source 4, and the second circuit 2 (DC-DC converter or active decoupling circuit) which is a back-end circuit arranged closer to the DC power source 3 than the first circuit 1 are configured to share the drive system circuits (excitation circuit 50, coil 7, and inverter 5) of the rotating electric machine 70. In this embodiment, AC power is supplied from the external AC power source 4 to the in-vehicle charging device 10 via an EMI filter FLT that reduces EMI (Electro Magnetic Interference) noise.

[0027] Specific circuit configurations are exemplified below. Fig. 2 and Fig. 3 illustrate an in-vehicle charging device 10 in a form in which the second circuit 2 is a DC-DC converter. Fig. 4 and Fig. 5 illustrate an in-vehicle charging device 10 in a form in which the second circuit 2 is an active decoupling circuit. Fig. 2 illustrates a first example of the in-vehicle charging device 10, Fig. 3 illustrates a second example of the in-vehicle charging device 10, Fig. 4 illustrates a third example of the in-vehicle charging device 10, and Fig. 5 illustrates a fourth example of the in-vehicle charging device 10. Figs. 2 and 4 illustrate a form in which the field current is mechanically switched by a brush 73, and Figs. 3 and 5 illustrate a form in which the field current is electrically switched by a drive circuit 74.

[0028] As shown in Fig. 2 and Fig. 3, the in-vehicle charging device 10 includes a main contactor 11, an OBC contactor 12, a grid contactor 13, and an excitation contactor 14. The main contactor 11 connects and disconnects the electrical connection between the output capacitor Cs and the DC power source 3, and complementarily connects and disconnects the electrical connection between the DC power source 3 and the DC side terminal T5d of the inverter 5 and the electrical connection between the DC power source 3 and the excitation circuit 50 in conjunction with the output capacitor Cs. The OBC contactor 12 connects and disconnects the electrical connection between the neutral point 7N and the output capacitor Cs. The grid contactor 13 selectively connects the AC side terminal T1a of the first circuit 1 (AC-DC converter) and the external AC power source 4 (connects and disconnects the AC side terminal T1a and the external AC power source 4). The excitation contactor 14 disconnects the electrical connection between the excitation circuit 50 and the field winding 7r.

[0029] When the grid contactor 13 is closed, the grid contactor 13 is brought into a conductive state, and the external AC power supply 4 and the in-vehicle charging device 10 (AC-DC converter) are electrically connected. AC power is supplied to the in-vehicle charging device 10 via the grid contactor 13 and the EMI filter FLT.

[0030] The main contactor 11 has two contacts, a main contactor first contact 11a and a main contactor second contact 11b. When the inverter 5 functions as the in-vehicle charging device 10, the main contactor second contact 11b is closed and the main contactor first contact 11a is opened. When the inverter 5 is used for driving control of the rotating electric machine 70, the main contactor first contact 11a is closed and the main contactor second contact 11b is opened, so that the inverter positive terminal T5P of the inverter 5 is connected to the DC power source 3 via the main contactor 11 and the excitation circuit 50 is connected to the DC power source 3 via the main contactor 11. When the vehicle is parked or when it is necessary to cut off the power supply to the rotating electric machine 70 due to an abnormality or the like, both the main contactor first contact 11a and the main contactor second contact 11b can be opened.

[0031] As shown by the dashed lines in the figure, the main contactor 11 (first contactor) is closed on the side of the main contactor first contact 11a, and the excitation contactor 14 (third contactor) is closed to electrically connect the DC power source 3 to the DC side terminal T5d of the inverter 5, and to electrically connect the DC power source 3 to the field winding 7r, and in a state where the OBC contactor 12 (second contactor) is opened, power is converted between the DC power source 3 and the rotating electric machine 70 via the inverter 5, and the field winding 7r is excited. That is, the rotating electric machine 70 is driven and controlled via the inverter 5. Naturally, at this time, the grid contactor 13 is opened. As shown by solid lines in the figure, the main contactor 11 is closed on the side of the main contactor second contact 11b to electrically connect the DC power source 3 and the output capacitor Cs, the excitation contactor 14 is opened, and in a state where the OBC contactor 12 is closed, power is converted between the external AC power source 4 and the DC power source 3 via the AC-DC converter (first circuit 1) and the DC-DC converter (second circuit 2) including the inverter 5. Naturally, at this time, the grid contactor 13 is closed.

[0032] In this way, by simply changing the connection form of the main contactor 11, the OBC contactor 12, and the excitation contactor 14 to the coil 7 and the field winding 7r, it is possible to realize a circuit that can switch between a function of driving and controlling the rotating electric machine 70 and a function of charging the DC power supply 3 with the external AC power supply 4. In other words, the in-vehicle charging device 10 can be configured with a simple configuration.

[0033] The configuration of the first circuit 1, which is an AC-DC converter, is common to all of the first, second, third, and fourth examples, and all of them are configured to include an excitation circuit 50. As shown in FIG. 2 and other figures, the first circuit 1 is configured to include an inductor L1. In AC-DC conversion, a phase difference occurs between the voltage phase and the current phase due to inductive impedance and capacitive impedance, and the power factor decreases due to the phase difference. The first circuit 1, which is an AC-DC converter, is configured to include a switching element 1S, and by controlling the switching element 1S, for example, the current phase is adjusted, the phase difference is compensated, and the power factor can be improved. That is, the first circuit 1 is configured to also function as a power factor correction (PFC) circuit that improves the power factor of DC power converted from AC power supplied from an external AC power source 4.

[0034] In this embodiment, the first circuit 1, which is an AC-DC converter, is configured to include an inductor L1 and a full bridge circuit using a switching element 1S. By including the full bridge circuit, the first circuit 1 can function as a bidirectional converter capable of AC-DC conversion and DC-AC conversion. For example, the in-vehicle charging device 10 can be used as a device having two functions: a function for charging the DC power source 3 with power supplied from the external AC power source 4, and a function for supplying AC power to a device outside the vehicle with power stored in the DC power source 3.

[0035] In recent years, it has been proposed to use the DC power supply 3 of an electric vehicle or a hybrid vehicle as an emergency power supply in the event of a disaster or the like. The first circuit 1 is provided with a full-bridge circuit, so that the DC power supply 3 can be used as such an emergency power supply. Of course, when the use of such a DC power supply 3 is not considered, the first circuit 1 may be configured as a unidirectional converter that performs only AC-DC conversion. In this case, the first circuit 1 may be configured to have, for example, a half-bridge circuit.

[0036] The circuit block diagram of FIG. 7 shows a charging device 10X as a comparative example of the on-board charging device 10 that utilizes a drive control system for a rotating electric machine 70. In the comparative example, the EMI filter FLT is omitted for simplification. In addition, in this comparative example, the configuration (excitation circuit 50) specific to a wound-field type rotating electric machine is omitted. The charging device 10X of the comparative example also charges the DC power source 3 of the vehicle drive device 9 with power supplied from an external AC power source 4, similar to the on-board charging device 10 of this embodiment. The charging device 10X of the comparative example also includes an AC-DC converter (comparative AC-DC converter 100) and a DC-DC converter (comparative DC-DC converter 200) similar to the on-board charging devices 10 of the first and second examples. However, in the on-vehicle charging devices 10 of the first and second examples, the drive circuit of the rotating electric machine 70 is shared with the DC-DC converter (second circuit 2), but in the charging device 10X of the comparative example, the drive circuit of the rotating electric machine 70 is shared with an AC-DC converter (comparative example AC-DC converter 100) rather than a DC-DC converter. When the rotating electric machine 70 is a wound-field type rotating electric machine, it is preferable that the excitation circuit 50 is shared with the comparative example DC-DC converter 200.

[0037] The comparative AC-DC converter 100 includes an inverter 5, multiple-phase coils 7, a single-phase arm 105 connected in parallel to the inverter 5, and an inductor L1 (first inductor). The multiple-phase coils 7 are short-circuited at a neutral point 7N, and the inductor L1 (first inductor) and an external AC power supply 4 are connected in series between the neutral point 7N and the midpoint of the single-phase arm 105. The three-phase arms that make up the inverter 5 are connected in parallel to form an apparent single arm, and together with the single-phase arm 105, form a full-bridge circuit.

[0038] The comparative DC-DC converter 200 is configured as a step-down DC-DC converter including an arm in which switching elements are connected in series so as to be switched complementarily, and a second inductor L2 connected to the midpoint of the arm. The comparative DC-DC converter 200 may be configured as a step-up converter or a step-up / step-down converter. As described above, when the rotating electric machine 70 is a wound-field type rotating electric machine, the comparative DC-DC converter 200 may be configured to include the excitation circuit 50.

[0039] The charging device 10X of the comparative example also includes a main contactor 11 and a grid contactor 13 similar to those of the in-vehicle charging device 10 of the first and second examples. The charging device 10X of the comparative example also includes an OBC contactor 12 that selectively connects the comparative AC-DC converter 100 (inverter 5) to the DC power source 3, or connects the comparative AC-DC converter 100 (inverter 5) to the comparative DC-DC converter 200. The OBC contactor 12 includes two contacts, an OBC contactor first contact 12a and an OBC contactor second contact 12b. When the inverter 5 functions as an in-vehicle charging device (the charging device 10X of the comparative example), the OBC contactor second contact 12b is closed and the OBC contactor first contact 12a is opened. When the inverter 5 is used to drive and control the rotating motor 70, the OBC contactor first contact 12a is closed and the OBC contactor second contact 12b is opened, and the inverter positive terminal T5P of the inverter 5 is connected to the DC power source 3 via the OBC contactor 12 and the main contactor 11.

[0040] The rotating electric machine that serves as the driving force source of the vehicle is designed to have a high power density and a small inductance. Therefore, when an AC-DC converter is formed by connecting an external AC power source 4 to a neutral point 7N as in the charging device 10X of the comparative example, the peak value of the harmonic current of the system current of the external AC power source 4 tends to be large during AC-DC conversion.

[0041] As a method for suppressing this, it is considered to increase the control frequency of the inverter 5 and the comparative DC / DC converter 200 included in the comparative AC / DC converter 100. When these control frequencies are increased, it is necessary to shorten the control period (control frequency) of the control device 8. Switching at a high frequency increases the loss in the switching elements of the comparative AC / DC converter 100 (inverter 5) and the comparative DC / DC converter 200, leading to a decrease in the efficiency of the charging device 10X of the comparative example. In addition, it becomes necessary to use a microcomputer or the like capable of high-speed operation as the control device 8, leading to an increase in the cost of the charging device 10X of the comparative example. In view of this point, in the charging device 10X of the comparative example, while the coil 7 is used as an inductor, an additional inductor L1 is arranged between the external AC power source 4 and the neutral point 7N of the coil 7 of the multiple phases to compensate for the inductance that is insufficient in the coil 7, thereby ensuring the necessary inductance. In the charging device 10X of the comparative example, an inductor (second inductor L2) is also arranged in the comparative DC-DC converter 200, and the number of inductors is greater than in the in-vehicle charging devices 10 of the first and second examples, which tends to increase system costs.

[0042] In view of this, the vehicle-mounted charging device 10 of the first and second examples is configured to suppress an increase in system cost. Specifically, among the AC-DC converter and the DC-DC converter that constitute the charging device, the AC-DC converter (first circuit 1) that requires an appropriate inductance is configured without using the drive circuit of the rotating electric machine 70 (the coil 7 of the rotating electric machine 70 and the inverter 5 that drives the rotating electric machine 70). That is, the vehicle-mounted charging device 10 of the first and second examples can configure an AC-DC converter that can perform AC-DC conversion while ensuring sufficient performance such as a power factor correction function, by the AC-DC converter (first circuit 1) in which an appropriate inductance is set using the inductor L1 that is independent of the drive circuit of the rotating electric machine 70 (the inverter 5, the coil 7, the field winding 7r). In addition, the second circuit 2 (for example, the DC-DC converter) that does not require a high inductance is configured by sharing the drive circuit of the rotating electric machine 70 (the inverter 5, the coil 7), and the cost of the vehicle-mounted charging device 10 can be reduced. Furthermore, since an appropriate inductance is set in the first circuit (AC-DC converter) by the inductor L1, there is no need to control the AC-DC converter with a short control period (high control frequency).

[0043] In the on-board charging device 10 of the first and second examples, the first circuit 1 that generates the first DC power and the second circuit 2 that generates the second power are connected via a DC link capacitor 6. In the AC-DC conversion by the first circuit 1, the pulsation of the second harmonic component of the AC frequency often remains in the first DC power. In the on-board charging device 10 of the first and second examples, the pulsation component of the first DC power is reduced by utilizing the smoothing effect of the DC link capacitor 6. For this reason, the DC link capacitor 6 is required to have a higher capacity than that of acting as a smoothing capacitor in the drive system of the rotating electric machine 70. As a result, it is likely that the capacitance of the DC link capacitor 6 needs to be larger than that when it is used only in the rotating electric machine drive system, which may lead to an increase in the size of the capacitor and an increase in cost.

[0044] In the on-board charging device 10 of the third and fourth examples shown in FIG. 4 and FIG. 5, the second circuit 2 is configured as an active decoupling circuit, and the pulsating component of the first DC power is reduced by the active decoupling circuit. Therefore, the first circuit 1 and the second circuit 2 are connected without other passive components such as the DC link capacitor 6. According to the experiments and simulations by the inventors, it was found that the DC link capacitor 6 of the on-board charging device 10 of the first and second examples needs about twice the capacity compared to the DC link capacitor 6 of the on-board charging device 10 of the third and fourth examples. Therefore, the on-board charging device 10 of the third and fourth examples is easier to realize miniaturization and reduction in system cost compared to the on-board charging device 10 of the first and second examples.

[0045] Hereinafter, the on-vehicle charging device 10 of the third and fourth examples will be described. As shown in Fig. 4 and Fig. 5, the on-vehicle charging device 10 includes a main contactor 11 that electrically connects and disconnects the DC power source 3 and the DC side terminal T5d of the inverter 5 and the DC power source 3 and the excitation circuit 50, an OBC contactor 12 that electrically connects and disconnects the neutral point 7N and the output capacitor Cs, an excitation contactor 14 that electrically disconnects the excitation circuit 50 and the field winding 7r, and a grid contactor 13 that selectively connects the AC side terminal T1a of the first circuit 1 (AC-DC converter) and the external AC power source 4 (connects and disconnects the AC side terminal T1a and the external AC power source 4). In the first and second examples, the main contactor 11 includes two contacts. Since a large current flows through both the main contactor first contact 11a and the main contactor second contact 11b, the component size of the main contactor 11 tends to be relatively large. In the on-board charging device 10 of the third and fourth examples, the main contactor 11 is configured to have only one contact. This prevents the main contactor 11 from becoming large in size, prevents the on-board charging device 10 from becoming large in size, and makes it easy to reduce system costs.

[0046] As described above, the first circuit 1 is an AC-DC converter, and in the third and fourth examples, the second circuit 2 is an active decoupling circuit. Also, as described above, in the third and fourth examples, the main contactor 11 is configured to have only one contact. The DC side terminal T1d of the first circuit 1, which is an AC-DC converter, and the DC side terminal T5d of the inverter 5 are connected without passing through other passive components (for example, the DC link capacitor 6). As shown by the dashed lines in the figure, in a state in which the main contactor 11 and the excitation contactor 14 are closed and the OBC contactor 12 is opened, power is converted between the DC power source 3 and the rotating electric machine 70 via the inverter 5, the field winding 7r is excited, and the rotating electric machine 70 is driven and controlled. Moreover, as shown by solid lines in the figure, with the main contactor 11 and the OBC contactor 12 both closed and the excitation contactor 14 open, power is converted between the external AC power source 4 and the DC power source 3 via the first circuit 1 which is an AC-DC converter and the second circuit 2 which is an active decoupling circuit including an inverter 5. Naturally, at this time, the grid contactor 13 is closed.

[0047] As shown in FIG. 4 and FIG. 5, the vehicle-mounted charging device 10 includes an OBC contactor 12 that electrically disconnects the neutral point 7N of the coil 7 and the output capacitor Cs. When the OBC contactor 12 is closed, the OBC contactor 12 is conductive, and the neutral point 7N is connected to the negative pole of the DC power supply via the output capacitor Cs. As described above, the drive control system of the rotating electric machine 70 and the vehicle-mounted charging device 10 share the main contactor 11. When the grid contactor 13 is closed and the inverter 5 functions as the vehicle-mounted charging device 10, the main contactor 11 is controlled to be closed and the OBC contactor 12 is controlled to be closed. That is, in a state in which both the main contactor 11 and the OBC contactor 12 are closed and the excitation contactor 14 is opened, power is converted between the external AC power supply 4 and the DC power supply 3 via the AC-DC converter and the active decoupling circuit including the inverter 5.

[0048] When the grid contactor 13 is opened and the inverter 5 is used to drive and control the rotating electric machine 70, the main contactor 11 and the excitation contactor 14 are closed and the OBC contactor 12 is controlled to be in an open state. That is, with the main contactor 11 and the excitation contactor 14 closed and the OBC contactor 12 in an open state, power is converted between the DC power source 3 and the rotating electric machine 70 via the inverter 5.

[0049] In this way, also in the third and fourth examples, a circuit can be realized that can switch between a function of driving and controlling the rotating electric machine 70 and a function of charging the DC power supply 3 with the external AC power supply 4, simply by changing the connection form of the OBC contactor 12 and the excitation contactor 14 to the coil 7 and the field winding 7r. That is, the in-vehicle charging device 10 can be configured with a simple configuration.

[0050] The circuit block diagram in FIG. 6 is a diagram in which the circuit block diagrams in FIG. 4 and FIG. 5 are divided by function for easy understanding. The AC-DC converter (first circuit 1) adjusts the power factor of the grid current Igrid supplied from the external AC power source 4 to a value close to "1" while boosting the voltage. However, a pulsation component caused by the AC frequency of the external AC power source 4 is superimposed on the first DC power output from the AC-DC converter. Specifically, the pulsation of the second harmonic component of the AC frequency of the external AC power source 4 is superimposed on the first DC power. The second circuit 2, which functions as an active decoupling circuit, reduces the pulsation of the second harmonic component and supplies the second DC power with the pulsation suppressed, preferably the second DC power with the pulsation removed, to the DC power source 3 to charge the DC power source 3.

[0051] Here, if the AC voltage supplied from the external AC power supply 4 is the "grid voltage Vgrid" and the AC current is the "grid current Igrid", the input power Pin supplied from the external AC power supply 4 is expressed by the following formula (1). Then, assuming that the input power Pin is converted to the first DC power with a power factor of "1", the relationship between the input power Pin and the first DC power can be approximated by the following formula (2). Formula (2) indicates that the first DC power contains a DC component Pdc and an AC component Prpl.

[0052] Pin = Vgrid Igrid (1) Pin ≒ Pdc + Prpl (2)

[0053] The active decoupling circuit functions to cause a current corresponding to the AC component Prpl included in equation (2), i.e., the AC component Prpl included in the first DC power, to flow through the active decoupling circuit so that the output power Pout to the DC power supply 3 is only the DC component Pdc included in equation (2) (equation (3)). The second circuit 2 as an active decoupling circuit operates to make the capacitor power Pcs, which is the power in the output capacitor Cs, equal to the AC component Prpl of the first DC power, as shown in the following equation (4).

[0054] Pout = Pdc (3) Prpl=Pcs ···(4)

[0055] Regarding the capacitor power Pcs, the relationship of the following formula (5) holds between the capacitor voltage Vcs and the capacitor current Ics, and therefore the capacitor power Pcs can be controlled by appropriately controlling the capacitor current Ics.

[0056] Pcs = Vcs Ics (5)

[0057] As described above, since the inductance of the coil 7 of the rotating electric machine 70 is small, the active decoupling circuit uses the inductor (coil 7) not to store energy but to pass current. Also, in the on-board charging device 10 of the third and fourth examples, the decoupling action is realized by the active decoupling circuit by making the capacitor current Ics a discontinuous current by pulse width modulation, rather than a so-called continuous current.

[0058] As described above, the inverter 5 is configured to have a plurality of arms in parallel, in which the upper-stage switching element 5U and the lower-stage switching element 5L are connected in series between the positive and negative poles of the direct current, according to the number of phases of the multi-phase alternating current. In this embodiment, the inverter 5 is configured to have three arms. When the inverter 5 functions as an active decoupling circuit, the multiple upper-stage switching elements 5U are simultaneously switched and the multiple lower-stage switching elements 5L are simultaneously switched. That is, the inverter 5 having multiple phase arms corresponding to the multi-phase alternating current can be used as an inverter (switching circuit) having a single-phase arm. Since the current flows in a distributed manner in the multiple arms, it is easy to suppress the wear of the inverter 5 even if the inverter 5 is used as a part of the in-vehicle charging device 10.

[0059] In addition, in the switching control, the sinusoidal capacitor current command I * Based on the capacitor current command I cs, a switching control signal (switching pulse) for the upper-stage switching element 5U and the lower-stage switching element 5L is generated. * The phase of the capacitor voltage Vcs coincides with the phase of the grid voltage Vgrid and the phase of the grid current Igrid. The phase of the capacitor voltage Vcs lags behind the capacitor current Ics by π / 2.

[0060] As described above, in the inverter 5, the multiple upper-side switching elements 5U and the multiple lower-side switching elements 5L are switched and controlled so that the phase of the current flowing through the output capacitor Cs coincides with the phase of the AC current in the AC-DC converter. The active decoupling circuit attenuates the AC harmonic components in the AC-DC converter by passing them through the output capacitor Cs. By matching the phase of the current flowing through the output capacitor Cs with the phase of the AC current in the AC-DC converter, the attenuation effect can be increased.

[0061] As described above, in this embodiment, it is necessary to pass a current (capacitor current Ics) corresponding to the AC component Prpl, which is a pulsating component of the first DC power, through the active decoupling circuit. * cs is set taking into consideration the magnitude relationship with the output voltage to the DC power supply 3 (=battery voltage Vbat).

[0062] The capacitor voltage Vcs needs to be lower than the battery voltage Vbat. In addition, since pulsation corresponding to the AC component Prpl of the first DC power occurs in the capacitor voltage Vcs, the capacitor voltage Vcs is set to a voltage lower than the battery voltage Vbat in consideration of the amplitude of the pulsation. That is, the capacitor voltage command V * The amplitude of cs “V * It is preferable that "cs_peak" be set so as to satisfy the following equation (6), where "Vrpl_peak" is the amplitude (the value from the amplitude center to the wave height (peak)) of the AC component "Vrpl" of the voltage in the first DC power.

[0063] V * cs_peak < Vbat-Vrpl_peak ···(6)

[0064] In addition, the battery voltage Vbat increases as the charging of the DC power supply 3 progresses, so the capacitor voltage command V *If the capacitor voltage Vcs is constant, the difference between the capacitor voltage Vcs and the battery voltage Vbat increases, the capacitor current Ics increases, and the loss also increases. Therefore, it is preferable that the capacitor voltage Vcs increases while satisfying the formula (6) as the battery voltage Vbat increases. That is, the capacitor voltage command V * It is preferable that cs is set so as to increase as the battery voltage Vbat increases while satisfying the formula (6).

[0065] In the third and fourth examples, when the inverter 5 functions as an active decoupling circuit, the multiple upper-stage switching elements 5U are simultaneously switched and the multiple lower-stage switching elements 5L are simultaneously switched. In the first and second examples in which the second circuit 2 is a DC-DC converter, detailed description of the operation of the DC-DC converter is omitted because it is a known configuration, but as in the third and fourth examples, the multiple upper-stage switching elements 5U are simultaneously switched and the multiple lower-stage switching elements 5L are simultaneously switched.

[0066] However, when currents of different magnitudes flow through the coil 7, torque is generated in the rotor 72. Since charging of the DC power source 3 is performed in a state where the vehicle is stopped, it is not preferable for torque to be generated in the rotor 72. For example, it is possible to cut off the power transmission from the rotor 72 to the wheels by a clutch or to restrict the rotation of the output member connected to the wheels or the rotation of the rotor 72 by a so-called parking brake. However, in these cases, the mechanism of the vehicle drive device 9 becomes complicated, and a mechanical load is generated in the gears of the vehicle drive device 9. In common with the first to fourth examples, the multiple upper-stage switching elements 5U are switched-controlled simultaneously, and the multiple lower-stage switching elements 5L are switched-controlled simultaneously, so that currents of approximately the same magnitude flow through each of the multiple-phase coils 7. Therefore, even if the coil 7 is also used as the in-vehicle charging device 10, it is possible to prevent almost no torque from being generated in the rotor 72.

[0067] However, when there is a difference in the magnitude of the current flowing through the coils 7 of the multiple phases due to individual differences or errors of the coils 7, there is a possibility that a torque, even if it is small, will be generated in the rotor 72. For example, when the rotating electric machine 70 is a permanent magnet type rotating electric machine (PMSM) having a permanent magnet in the rotor 72, a field magnet is always present in the rotor 72, so that a torque may be generated in the rotor 72. However, when the rotating electric machine 70 is a wound field type synchronous rotating electric machine (EESM) as in this embodiment, a field magnet is not generated in the rotor 72 unless the field winding 7r is energized. When the inverter 5 and the coils 7 are used as the on-board charging device 10, the excitation contactor 14 is opened, the field winding 7r is not excited, and the rotor 72 does not generate a field magnet. Therefore, even if there is a difference in the magnitude of the current flowing through the coils 7 of the multiple phases due to individual differences or errors of the coils 7, it is possible to prevent the rotor 72 from generating a torque in common to the first to fourth examples. That is, in the in-vehicle charging device 10 of this embodiment in which the rotating electric machine 70 is a wound-field type synchronous rotating electric machine, it is easier to prevent torque from being generated in the rotor 72 compared to when the rotating electric machine 70 is a permanent magnet type rotating electric machine. Therefore, there is even less risk of mechanical load being generated on the gears of the vehicle drive device 9, and the in-vehicle charging device 10 can be appropriately configured.

[0068] According to the first and second examples described above, among the AC-DC converter and the DC-DC converter constituting the in-vehicle charging device 10, the AC-DC converter that requires an appropriate inductance is configured using the excitation circuit 50 without using the drive circuit of the rotating electric machine 70 (the coil 7 of the rotating electric machine 70 and the inverter 5 that drives the rotating electric machine 70). When the coil 7 of the rotating electric machine 70 is used in the in-vehicle charging device 10, it may be difficult to ensure the required performance due to the small inductance of the coil 7. However, according to this configuration, it is possible to configure an AC-DC converter that can perform AC-DC conversion while ensuring sufficient performance such as a power factor correction function by a circuit that can set an appropriate inductance without using the coil 7 of the rotating electric machine 70 and using the excitation circuit 50. In addition, a DC-DC converter that does not require a high inductance can be configured using a stator coil (coil 7) and an inverter 5, and the cost of the in-vehicle charging device 10 can be reduced. Furthermore, since an appropriate inductance can be set for the AC-DC converter, it is not necessary to control the AC-DC converter at a short control period (high control frequency), and the loss of the switching element 1S constituting the AC-DC converter can be easily reduced, and the system efficiency of the in-vehicle charging device 10 can be easily improved.

[0069] According to the above-mentioned third and fourth examples, the AC-DC converter, which requires an appropriate inductance, is configured without using the drive circuit of the rotating electric machine 70 (the coil 7 of the rotating electric machine 70 and the inverter 5 that drives the rotating electric machine 70). When the coil 7 of the rotating electric machine 70 is used in the vehicle-mounted charging device 10, it may be difficult to ensure the required performance due to the small inductance of the coil 7. However, according to this configuration, it is possible to configure an AC-DC converter capable of AC-DC conversion while ensuring sufficient performance such as a power factor correction function by a circuit that can set an appropriate inductance using the excitation circuit 50 without using the coil 7 of the rotating electric machine 70. Furthermore, since an appropriate inductance can be set in the AC-DC converter, it is not necessary to control the AC-DC converter with a short control period (high control frequency), and the loss of the switching element 1S that configures the AC-DC converter is also easily reduced. Therefore, the system efficiency of the vehicle-mounted charging device 10 is also easily increased. In addition, since a pulsating component is superimposed on the DC converted from the AC by the AC-DC converter, a DC-DC converter is generally arranged in the rear stage of the AC-DC converter via a decoupling capacitor for reducing the pulsating component. According to this configuration, the pulsating component can be reduced by an active decoupling circuit connected to the AC-DC converter without using such a decoupling capacitor, so that the circuit size can be easily kept small. In addition, the inverter 5 for driving the rotating electric machine 70 and the coil 7 of the rotating electric machine 70 can be used as switching elements and inductors constituting the active decoupling circuit, so that the circuit size of the entire in-vehicle system can be easily kept small. [Explanation of symbols]

[0070] 1: first circuit, 2: second circuit, 3: DC power supply, 4: external AC power supply, 5: inverter, 7: coil (stator coil), 7N: neutral point, 9: vehicle drive device, 10: on-board charging device, 11: main contactor (first contactor), 12: OBC contactor (second contactor), 14: excitation contactor (third contactor), 50: excitation circuit, 70: rotating electric machine, Cs: output capacitor, T1d: DC side terminal, T5d: DC side terminal

Claims

1. An on-board charging device for charging the DC power supply of a vehicle drive device with power supplied from an external AC power supply, the on-board charging device comprising: a stator having multiple-phase stator coils connected to each other at a neutral point; and a rotor having a field winding that generates a field magnetic flux, the stator having a wound-field type rotating electric machine that serves as a driving force source for wheels; a DC power supply; an inverter connected between the stator coil and the DC power supply for converting power between DC and multiple-phase AC; and an excitation circuit connected between the field winding and the DC power supply for exciting the field winding, a first circuit including the excitation circuit and configured to convert power between AC power from the external AC power supply and a first DC power; a second circuit configured to include the inverter, the stator coils of a plurality of phases, and an output capacitor, and to generate a second DC power from the first DC power for charging the DC power supply; An on-board charging device, wherein the output capacitor is connected between the neutral point of the stator coil and a negative pole of DC.

2. a first contactor that electrically connects the DC power source to a DC side terminal of the inverter and electrically disconnects the DC power source to the excitation circuit; a second contactor that electrically disconnects the neutral point and the output capacitor; a third contactor that cuts off an electrical connection between the excitation circuit and the field winding, the first circuit is an AC-DC converter; the second circuit is an active decoupling circuit; a DC side terminal of the AC-DC converter and a DC side terminal of the inverter are connected without any other passive components; in a state in which the first contactor and the third contactor are closed and the second contactor is opened, power is converted between the DC power source and the rotating electric machine via the inverter and the field winding is excited; 2. The on-board charging device according to claim 1, wherein, when the first contactor and the second contactor are both closed and the third contactor is open, power is converted between the external AC power source and the DC power source via the AC-DC converter and the active decoupling circuit including the inverter.

3. a first contactor that electrically connects and disconnects the output capacitor and the DC power source, and that, in a complementary manner with the output capacitor, connects and disconnects an electrical connection between the DC power source and a DC side terminal of the inverter and an electrical connection between the DC power source and the excitation circuit; a second contactor that electrically disconnects the neutral point and the output capacitor; a third contactor that cuts off an electrical connection between the excitation circuit and the field winding, the first circuit is an AC-DC converter; the second circuit is a DC-DC converter; the first contactor is closed to electrically connect the DC power source and a DC side terminal of the inverter, and the third contactor is closed, and in a state where the second contactor is opened, power is converted between the DC power source and the rotating electric machine via the inverter, and the field winding is excited; 2. The in-vehicle charging device according to claim 1, wherein the first contactor is closed to electrically connect the DC power source and the output capacitor while the third contactor is opened, and in a state where the second contactor is closed, power is converted between the external AC power source and the DC power source via the AC-DC converter and the DC-DC converter including the inverter.

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