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 is constructed by containing: an AC and DC converter 1 that converts a power between an AC power on an external AC power supply 4 and a first DC power; an inverter 5; a coil 7 with a plurality of phases; and an output capacitor Cs, and comprises an active decoupling circuit 2 that generates a second DC power for charging a DC power supply 3 from the first DC power. A DC side terminal T1d of the AC-DC converter 1 and a DC side terminal T5d of the inverter 5 are connected without passing through the other passive component, and the output capacitor Cs is connected to between a neutral point 7N of the coil 7 and a DC negative electrode.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] JP2022-503713A discloses an on-board 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 DC power source 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 on-board 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. The current after AC-DC conversion generates ripples with a frequency twice the frequency (system frequency) of the external AC power source (310). The DC-DC converter reduces the ripples and generates a battery current for charging the DC power source. A smoothing capacitor is also provided between the AC-DC converter and the DC-DC converter. [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 conceivable to increase the control frequency of the inverter constituting the AC-DC converter. Alternatively, it is conceivable 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, leading to an increase in the cost of the vehicle-mounted charging device. Alternatively, as another method, it is conceivable 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. In addition, a large capacity is required for the smoothing capacitor provided between the AC-DC converter and the DC-DC converter, which is likely to lead to an increase in the size and cost of the vehicle-mounted charging device due to the increase in size.

[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, which includes a rotating electric machine that serves as a driving force source for wheels, an inverter that converts power between DC and multiple-phase AC, and a DC power supply connected to the inverter, with power supplied from an external AC power supply, and is equipped with an AC-DC converter that converts power between AC power on the external AC power supply side and a first DC power, and an active decoupling circuit that includes the inverter, the multiple-phase coils, and an output capacitor and generates second DC power from the first DC power to charge the DC power supply, wherein a DC side terminal of the AC-DC converter and a DC side terminal of the inverter are connected without passing through any other passive components, and the output capacitor is connected between the neutral point of the coil and a negative pole of the DC.

[0008] According to this configuration, the AC-DC converter, which requires an appropriate inductance, is configured without using a drive circuit of the rotating electric machine (a coil of the rotating electric machine and an inverter that drives the rotating electric machine). When a coil of a rotating electric machine is used in an in-vehicle charging device, it may be difficult to ensure the required performance due to the small inductance of the coil. However, according to this configuration, an AC-DC converter capable of AC-DC conversion can be configured by an AC-DC converter in which an appropriate inductance can be set without using a coil of a rotating electric machine, while ensuring sufficient performance such as a power factor correction function. 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 that constitutes the AC-DC converter can be easily reduced. Therefore, the system efficiency of the in-vehicle charging device can be 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 often arranged in the rear stage of the AC-DC converter via a decoupling capacitor for smoothing the pulsating component. According to this configuration, the pulsating components can be reduced by the 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 for driving the rotating electric machine and the coil of the rotating electric machine can be used as switching elements and inductors that constitute the active decoupling circuit, so that the circuit size of the entire vehicle-mounted system can be easily kept small. That is, according to this configuration, it is possible to configure an on-vehicle 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 using 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 an example of an on-board charging device using a drive control system for a rotating electric machine. [Diagram 3] A functional block diagram that is a variation of the circuit block diagram shown in Figure 2. [Figure 4] Diagram showing current flow in an active decoupling circuit (output capacitor charging (capacitor current is positive and increasing)) [Diagram 5] Diagram showing current flow in an active decoupling circuit (output capacitor charging (capacitor current is positive and decreasing)) [Figure 6] Diagram showing current flow in an active decoupling circuit (output capacitor discharging (capacitor current is negative and the absolute value of the capacitor current is increasing)) [Figure 7] Diagram showing current flow in an active decoupling circuit (output capacitor discharging (capacitor current is negative and the absolute value of the capacitor current is decreasing)) [Figure 8] Waveform diagram showing the relationship between grid voltage, grid current, capacitor current, and capacitor voltage [Figure 9] Waveform diagram showing pulse width modulation when controlling capacitor current [Figure 10] A circuit block diagram showing a first comparative example of an on-board charging device using a drive control system for a rotating electric machine. [Figure 11] A circuit block diagram showing a second comparative example of an on-board charging device using a drive control system for a rotating electric machine. 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 diagram of FIG. 2 shows 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] As shown in Fig. 2, the vehicle-mounted charging device 10 is a device that charges a DC power supply 3 of a vehicle drive device 9 with power supplied from an external AC power supply 4 (grid power supply, 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 and the coil 7 of the rotating electric machine 70 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 an interior permanent magnet type rotating electric machine (IPMSM: Interior Permanent Magnet Synchronous Motor) having a stator 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 in a stator core, and a rotor in which a permanent magnet is arranged in a rotor core. Such a configuration is well known, and in this embodiment, the stator core, stator, rotor core, rotor, permanent magnets, etc. are not illustrated. In this embodiment, a Y-type (star type) in which three-phase coils 7 are short-circuited at a neutral point 7N is illustrated. However, the rotating electric machine 70 may be, for example, provided with two sets of three-phase coils 7 and 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.

[0014] 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.

[0015] 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.

[0016] 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. 3) for the DC power source 3, and a voltage sensor (battery voltage sensor 32) that detects a terminal voltage (battery voltage Vbat: see FIG. 3) of the DC power source 3.

[0017] 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.

[0018] 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.

[0019] 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 current (U-phase current Iu, V-phase current Iv, and W-phase current Iw in this embodiment: see FIG. 2, etc.) flowing through the coil 7 of each phase into vector components of a d-axis, which is the direction of the magnetic field generated by a permanent magnet arranged in the rotor, 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 into which the coordinates are converted 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.

[0020] 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 magnetic pole position (electrical angle) of the rotor of the rotating electric machine 70 at each point in time and the rotation speed (angular velocity) of the rotor 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).

[0021] 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.

[0022] An in-vehicle charging device 10 of this embodiment charges a DC power supply 3 of a vehicle drive device 9 with power supplied from an external AC power supply 4. As shown in FIG. 2, the in-vehicle charging device 10 includes an AC / DC converter 1 (AC / DC converter) that is connected to the external AC power supply 4 and converts AC power from the external AC power supply 4 into first DC power, and an active decoupling circuit 2 that generates second DC power from the first DC power to charge the DC power supply 3. Although details will be described later, in this embodiment, the active decoupling circuit 2 includes an inverter 5, a multi-phase coil 7, and an output capacitor Cs. The active decoupling circuit 2 also functions as a so-called DC / DC converter.

[0023] In the vehicle-mounted charging device 10 of this embodiment, the DC side terminal T1d of the AC-DC converter 1 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). Specifically, the DC side positive terminal T1P of the AC-DC converter 1 and the inverter positive terminal T5P of the inverter 5 are connected, and the DC side negative terminal T1N of the AC-DC converter 1 and the inverter negative terminal T5N of the inverter 5 are connected. In addition, an output capacitor Cs is connected between the neutral point 7N of the coil 7 and the negative pole of the DC. In this embodiment, AC power is supplied from the external AC power source 4 to the vehicle-mounted charging device 10 via an EMI filter FLT that reduces EMI (Electro Magnetic Interference) noise.

[0024] The AC-DC converter 1 and the active decoupling circuit 2 are configured to include switching elements (switching elements indicated by symbols 1S and 5S in FIG. 2), and these switching elements are controlled by a control device 8 that drives and controls the rotating electric machine 70 via the inverter 5. As will be described later, the in-vehicle charging device 10 is configured to include contactors (main contactor 11, OBC contactor 12 (second contactor), and grid contactor 13 (third contactor)). These contactors are also controlled by the control device 8, or by 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.

[0025] When charging the DC power supply 3, power is supplied from the external AC power supply 4 to the DC power supply 3. Therefore, in terms of circuit configuration, the AC-DC converter 1 arranged relatively closer to the external AC power supply 4 (upstream side) may be referred to as a front-end circuit or a first circuit, and the active decoupling circuit 2 arranged relatively closer to the DC power supply 3 (downstream side) may be referred to as a back-end circuit or a second circuit. In this embodiment, the AC-DC converter 1, which is a front-end circuit connected to the external AC power supply 4, is configured by a circuit formed separately from the vehicle drive device 9, and the active decoupling circuit 2, which is a back-end circuit arranged closer to the DC power supply 3 than the AC-DC converter 1, is configured to share the drive system circuit (coil 7 and inverter 5) of the rotating electric machine 70.

[0026] As described above, in the in-vehicle charging device 10 of this embodiment, the DC side terminal T1d of the AC-DC converter 1 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). That is, the first circuit and the second circuit are connected without passing through passive components such as a smoothing capacitor. For example, in a form in which the first circuit and the second circuit are connected through a smoothing capacitor (such as the first comparative charging device 10Y illustrated in FIG. 10), the first circuit (in this case, the AC-DC converter 1) and the second circuit (in this case, the DC-DC converter 20) can operate independently, and the switching element 1S of the first circuit and the switching element 5S of the second circuit are controlled independently without needing to be switched in cooperation. On the other hand, in this embodiment, the first circuit (the AC-DC converter 1) and the second circuit (the active decoupling circuit 2) operate in cooperation. Therefore, the switching element 5S of the second circuit, which is the latter circuit, is controlled to operate in conjunction with the first circuit, as will be described in detail later with reference to FIG.

[0027] As shown in Fig. 2, the AC-DC converter 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 AC-DC converter 1 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. In other words, the AC-DC converter 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.

[0028] In this embodiment, the AC-DC converter 1 is configured to include an inductor L1 and a full bridge circuit using a switching element 1S. By including the full bridge circuit, the AC-DC converter 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 the power stored in the DC power source 3.

[0029] 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 AC-DC converter 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 AC-DC converter 1 may be configured as a unidirectional converter that performs only AC-DC conversion. In this case, the AC-DC converter 1 may be configured to have, for example, a half-bridge circuit.

[0030] 2, the vehicle-mounted charging device 10 includes a grid contactor 13 that selectively connects the AC side terminal T1a of the AC-DC converter 1 to the external AC power source 4 (connects and disconnects the AC side terminal T1a to and from the external AC power source 4). The grid contactor 13 is also formed of, for example, a relay. When the grid contactor 13 is closed, the grid contactor 13 is in a conductive state, and the external AC power source 4 and the vehicle-mounted charging device 10 (AC-DC converter 1) are electrically connected to each other.

[0031] As shown in FIG. 2, the vehicle-mounted charging device 10 includes an OBC contactor 12 that electrically connects and disconnects the neutral point 7N of the coil 7 and the output capacitor Cs. The OBC contactor 12 is also configured by, for example, a relay. 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 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 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, with both the main contactor 11 and the OBC contactor 12 closed, power is converted between the external AC power source 4 and the DC power source 3 via the active decoupling circuit 2 including the AC-DC converter 1 and the inverter 5.

[0032] When the inverter 5 is used for driving control of the rotating electric machine 70, the main contactor 11 is closed and the OBC contactor 12 and the grid contactor 13 are controlled to be open. That is, with the main contactor 11 closed and the OBC contactor 12 open, power is converted between the DC power source 3 and the rotating electric machine 70 via the inverter 5.

[0033] In this way, by simply changing the connection form of the OBC contactor 12 to the coil 7, 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. That is, the in-vehicle charging device 10 can be configured with a simple configuration.

[0034] As described above, the in-vehicle charging device 10 is configured to include the AC-DC converter 1 and the active decoupling circuit 2. The circuit block diagram of FIG. 3 is a functional block diagram of the circuit block diagram of FIG. 2, which is shown in order to facilitate understanding. The AC-DC converter 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 1. 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 active decoupling circuit 2 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.

[0035] Here, if the AC voltage supplied from the external AC power supply 4 is the "grid voltage Vgrid", the AC current is the "grid current Igrid", and their respective amplitudes (a positive value from the center of the amplitude to the wave height; the same applies to "_peak" below) are "Vgrid_peak" and "Igrid_peak", then the grid voltage Vgrid and the grid current Igrid are expressed by the following equations (1) and (2).

[0036]

number

number

[0037] Assuming that the input power Pin input from the external AC power supply 4 to the AC-DC converter 1 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 is expressed by the following formulas (3) to (5). Formula (3) shows that the first DC power contains a DC component Pdc and an AC component Prpl. Formula (4) shows the DC component Pdc of the first DC power, and formula (5) shows the AC component Prpl which is a pulsating component of the first DC power.

[0038]

number

number

number

[0039] The active decoupling circuit 2 functions (equation (6)) by causing a current corresponding to the AC component Prpl shown in equation (5) to flow within the active decoupling circuit 2 so that the output power Pout to the DC power supply 3 consists only of the DC component Pdc shown in equation (4). Therefore, the active decoupling circuit 2 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 (7).

[0040]

number

number

[0041] Regarding the capacitor power Pcs, the relationship of the following formula (8) 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.

[0042]

number

[0043] 4 to 7 show the current flow in the active decoupling circuit 2. The waveform diagram in FIG. 8 shows the relationship between the grid voltage Vgrid, the grid current Igrid, the capacitor current Ics, and the capacitor voltage Vcs. As described above, in the active decoupling circuit 2, the capacitor current Ics is controlled, so FIG. 8 shows the capacitor current command I * The waveform diagram in FIG. 9 also shows the capacitor current command I cs, which is switched by pulse width modulation control. * cs, the capacitor current Ics, and the switching pulses.

[0044] Figures 4 and 5 show the current flow when the capacitor current Ics flowing through the output capacitor Cs is a positive value with the direction of the arrow shown in Figure 3 being positive, and the output capacitor Cs is being charged, which corresponds to the current flow during the period marked "Charging" in Figures 8 and 9. Figures 6 and 7 show the current flow when the capacitor current Ics flowing through the output capacitor Cs is a negative value and the output capacitor Cs is being discharged, which corresponds to the current flow during the period marked "Discharging" in Figures 8 and 9.

[0045] As described above, since the inductance of the coil 7 of the rotating electric machine 70 is small, the active decoupling circuit 2 uses an inductor (coil 7) not for storing energy but for passing current. Also, in the on-board charging device 10 of this embodiment, the decoupling action of the active decoupling circuit 2 is realized by making the capacitor current Ics a discontinuous current by pulse width modulation, rather than a so-called continuous current.

[0046] 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 the active decoupling circuit 2, 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.

[0047] In addition, since the current of approximately the same magnitude flows through each of the coils 7 of the multiple phases, excluding individual differences and errors, even if the coils 7 are also used as the in-vehicle charging device 10, almost no torque is generated in the rotor. Since the 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. For example, it is possible to cut off the power transmission from the rotor to the wheels by a clutch or the like, or to restrict the rotation of the output member connected to the wheels or the rotation of the rotor by a so-called parking brake or the like. However, in these cases, the mechanism of the vehicle drive device 9 becomes complicated, or a mechanical load is generated on the gears of the vehicle drive device 9 or the like. In this embodiment, the rotor is controlled so that no torque is generated, so that the in-vehicle charging device 10 can be appropriately configured without generating almost no mechanical load on the gears of the vehicle drive device 9 or the like.

[0048] The waveform diagram in FIG. 9 shows the modulation pulses of the pulse width modulation of the upper-stage switching element 5U and the lower-stage switching element 5L when controlling the capacitor current Ics. The sinusoidal waveform is the capacitor current command I * cs, and the capacitor current command I *Based on the capacitor current Ics, the control device 8 generates a modulated pulse. Therefore, the actual capacitor current Ics has a triangular waveform. As is clear from FIG. 9, the inverter 5 is controlled by the modulated pulse into three states: a first state in which all upper-stage switching elements 5U are on (ON) and all lower-stage switching elements 5L are off (OFF), a second state in which all upper-stage switching elements 5U are off and all lower-stage switching elements 5L are on, and a third state in which all upper-stage switching elements 5U and all lower-stage switching elements 5L are off. In the third state, all switching elements 5S of the inverter 5 are off.

[0049] FIG. 4 shows the flow of current when the capacitor current Ics flowing through the output capacitor Cs increases with a positive value, with the direction of the arrow shown in FIG. 2 and FIG. 3 being positive, and the output capacitor Cs is being charged. In the waveform diagrams shown in FIG. 8 and FIG. 9, during the period marked "Charging", the capacitor current Ics increases in proportion to the capacitor current command I * This corresponds to a period during which the amplitude of the first DC power increases from the center of amplitude of the first DC power to the wave height (peak). The switching element 5S of the inverter 5 is controlled to be in the first state. The AC component Prpl of the first DC power is consumed to charge the output capacitor Cs, and substantially only the DC component Pdc of the first DC power is supplied to the DC power supply 3 as the second DC power.

[0050] FIG. 5 shows the current flow when the capacitor current Ics is decreasing with a positive value and charging the output capacitor Cs. In the waveform diagrams shown in FIG. 8 and FIG. 9, during the period marked "Charging", the capacitor current Ics is greater than the capacitor current command I *This corresponds to the period during which the current Ics decreases from the wave height (peak) of the output capacitor Cs toward the center of amplitude. The switching element 5S of the inverter is controlled to be in the third state. The capacitor current Ics decreases while circulating between the output capacitor Cs and the output capacitor Cs through the freewheeling diode connected in parallel to the lower-side switching element 5L, or through the lower-side switching element 5L (when using the reverse conduction of the body diode or E-GaN transistor).

[0051] That is, in the "charging" phase, the lower-stage switching element 5L is controlled to be constantly off, and the upper-stage switching element 5U is switched by pulse width modulation control.

[0052] FIG. 7 shows the current flow when the capacitor current Ics is negative and the absolute value of the capacitor current Ics is decreasing while discharging the output capacitor Cs. In the waveform diagrams shown in FIG. 8 and FIG. 9, during the period marked "Discharging", the absolute value of the capacitor current Ics is greater than the capacitor current command I * This corresponds to a period during which the amplitude of the first DC power is decreasing from the wave height (bottom) of the output capacitor Cs toward the center of the amplitude. The switching element 5S of the inverter is controlled to be in the third state. The current flowing due to the charge discharged from the output capacitor Cs flows to the DC power supply 3 through the freewheel diode connected in parallel to the upper-stage switching element 5U, or through the lower-stage switching element 5L (when reverse conduction of a body diode or E-GaN transistor is used). That is, the AC component Prpl of the first DC power is reduced by the charge discharged from the output capacitor Cs, and approximately only the DC component Pdc of the first DC power is supplied to the DC power supply 3 as the second DC power.

[0053] FIG. 6 shows the current flow when the capacitor current Ics is negative and the absolute value of the capacitor current Ics is increasing to discharge the output capacitor Cs. In the waveform diagrams shown in FIG. 8 and FIG. 9, during the period marked "Discharging", the absolute value of the capacitor current Ics increases as the capacitor current command I *This corresponds to the period during which the amplitude of the capacitor current Ics increases from the center to the bottom. The inverter switching element 5S is controlled to be in the second state. The absolute value of the capacitor current Ics increases while circulating between the output capacitor Cs and the lower-stage switching element 5L.

[0054] That is, in the "Discharging" phase, contrary to the "Charging" phase, the upper-stage switching element 5U is controlled to be constantly off, and the lower-stage switching element 5L is switched by pulse width modulation control.

[0055] As shown in FIG. 8, the capacitor current command I * The phase of the grid voltage Vgrid and the grid current Igrid coincide with each other. The grid voltage Vgrid and the grid current Igrid are expressed by the above formulas (1) and (2), and the AC component Prpl of the input power Pin is expressed by the above formula (5). Therefore, the capacitor current command I * cs is the capacitor current command I * The amplitude of cs is I * The capacitor voltage Vcs is expressed by the following equation (9) as cs_peak. The phase of the capacitor voltage Vcs lags behind the capacitor current Ics by π / 2. The capacitor voltage Vcs is expressed by the following equation (10) with the amplitude of the capacitor voltage Vcs as Vcs_peak.

[0056]

number

number

[0057] As described above, in the inverter 5, the multiple upper-side switching elements 5U and the multiple lower-side switching elements 5L are switching-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 1. The active decoupling circuit 2 attenuates the AC harmonic components in the AC-DC converter 1 by flowing 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 1, the attenuation effect can be increased.

[0058] 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 2. That is, it is necessary to realize the above-mentioned "Charging" current loop and "Discharging" current loop for the output capacitor Cs. For this reason, the capacitor current command I * cs is set taking into consideration the magnitude relationship with the output voltage to the DC power supply 3 (=battery voltage Vbat).

[0059] To realize the "charging" current loop (FIG. 4) and the "discharging" current loop (FIG. 7), the capacitor voltage Vcs needs to be lower than the battery voltage Vbat. Furthermore, 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, taking into consideration the amplitude of the pulsation. That is, the capacitor voltage command V * The amplitude of cs “V * The amplitude of the AC component “Vrpl” of the voltage of the first DC power is set as Vrpl_peak so as to satisfy the following equation (11).

[0060]

number

[0061] 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 (11) 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 (11).

[0062] Hereinafter, the advantages of the in-vehicle charging device 10 will be described with reference to a comparative example. In the comparative example, the EMI filter FLT is omitted for simplification. The circuit block diagram of FIG. 10 shows a first comparative example (first comparative example charging device 10Y) of the in-vehicle charging device 10 that utilizes a drive control system of the rotating electric machine 70. The first comparative example charging device 10Y 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 in-vehicle charging device 10 of this embodiment. As shown in FIG. 10, the first comparative example charging device 10Y includes an AC-DC converter 1 (AC / DC converter) 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 DC-DC converter 20 (DC / DC converter) that converts the first DC power converted by the AC-DC converter 1 into a second DC power.

[0063] In the first comparative charging device 10Y, the AC-DC converter 1 arranged relatively closer to the external AC power source 4 (upstream side) can be referred to as a front-end circuit or a first circuit, and the DC-DC converter 20 arranged relatively closer to the DC power source 3 (downstream side) can be referred to as a back-end circuit or a second circuit. Also in the first comparative charging device 10Y, the AC-DC converter 1 which is a front-end circuit connected to the external AC power source 4 is configured by a circuit formed separately from the vehicle drive device 9, and the DC-DC converter 20 which is a back-end circuit arranged closer to the DC power source 3 than the AC-DC converter 1 is configured to share the drive system circuit (coil 7 and inverter 5) of the rotating electric machine 70.

[0064] The configuration of the first comparative example charging device 10Y will be described below. The configuration of the AC-DC converter 1 is similar to that of the AC-DC converter 1 of the above-described in-vehicle charging device 10, and detailed description thereof will be omitted.

[0065] Like the active decoupling circuit 2 of the above-mentioned in-vehicle charging device 10, the DC-DC converter 20 is also configured to include an inverter 5, multiple phase coils 7, an output capacitor Cs, and an OBC contactor 12. However, while the active decoupling circuit 2 connects the DC side terminal T1d of the AC-DC converter 1 and the DC side terminal T5d of the inverter 5 without passing through other passive components (e.g., the DC link capacitor 6), the DC-DC converter 20 of the first comparative example charging device 10Y connects the DC side terminal T1d of the AC-DC converter 1 and the DC side terminal T5d of the inverter 5 through the DC link capacitor 6. In the active decoupling circuit 2, the output capacitor Cs is connected between the neutral point 7N of the coil 7 and the negative pole of the DC, but in the first comparative example charging device 10Y, the output capacitor Cs is connected between the neutral point 7N of the coil 7 and the negative pole of the DC, and is also connected between the positive pole of the DC power source 3 and the negative pole of the DC (the same as the negative pole of the DC power source 3). In other words, the capacitor voltage Vcs, which is the voltage across the output capacitor Cs, becomes the battery voltage Vbat, which is the voltage across the DC power source 3.

[0066] In the first comparative charging device 10Y, the main contactor 11 selectively connects the positive electrode of the inverter 5 (inverter positive terminal T5P) and the positive electrode of the output of the DC-DC converter 20 (positive terminal of the output capacitor Cs, neutral point 7N when the OBC contactor 12 is closed) to the positive electrode of the DC power source 3. That is, 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 an in-vehicle charging device (first comparative charging device 10Y), 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, and the inverter positive terminal T5P of the inverter 5 is connected to the DC power source 3 via the main contactor 11. Furthermore, when the vehicle is parked or when it is necessary to cut off the power supply to the rotating motor 70 due to an abnormality or the like, both the main contactor first contact 11a and the main contactor second contact 11b can be placed in an open state.

[0067] The circuit block diagram of FIG. 11 shows a second comparative example (second comparative example charging device 10X) of the on-board charging device 10 using a drive control system of the rotating electric machine 70. Like the on-board charging device 10 of the present embodiment and the first comparative example charging device 10Y, the second comparative example charging device 10X also charges the DC power source 3 of the vehicle drive device 9 with power supplied from the external AC power source 4. Like the first comparative example charging device 10Y, the second comparative example charging device 10X also includes an AC-DC converter (comparative example AC-DC converter 100) and a DC-DC converter (comparative example DC-DC converter 200). However, while in the first comparative example charging device 10Y, the DC-DC converter 20 shares the drive system circuit of the rotating electric machine 70, in the second comparative example charging device 10X, the AC-DC converter (comparative example AC-DC converter 100) shares the drive system circuit of the rotating electric machine 70. 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.

[0068] In the second comparative example charging device 10X, the DC-DC converter (comparative example DC-DC converter 200) is formed independently without sharing the drive circuit of the rotating electric machine 70. The comparative example 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 example DC-DC converter 200 may be configured as a step-up converter or a step-up / step-down converter.

[0069] The second comparative charging device 10X also includes a main contactor 11 and a grid contactor 13 similar to those of the first comparative charging device 10Y of the vehicle-mounted charging device 10. The second comparative charging device 10X 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 the vehicle-mounted charging device (second comparative charging device 10X), 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.

[0070] 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 second comparative example charging device 10X, 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.

[0071] 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, the control period (control frequency) of the control device 8 must also be shortened. 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 second comparative charging device 10X. 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 second comparative charging device 10X. In view of this point, in the second comparative charging device 10X, while using the coil 7, in order to compensate for the inductance that is insufficient in the coil 7, an inductor L1 is arranged between the external AC power source 4 and the neutral point 7N of the coils 7 of the multiple phases to ensure the necessary inductance. In the second comparative example charging device 10X, an inductor (second inductor L2) is also arranged in the comparative example DC-DC converter 200, and the number of inductors is greater than in the first comparative example charging device 10Y and the in-vehicle charging device 10 of this embodiment, which tends to increase system costs.

[0072] In view of this, the first comparative charging device 10Y 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 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 first comparative charging device 10Y can configure the AC-DC converter 1 that can perform AC-DC conversion while ensuring sufficient performance such as a power factor correction function, by the AC-DC converter 1 in which an appropriate inductance is set using the inductor L1. In addition, the DC-DC converter 20 that does not require a high inductance is configured by sharing the drive circuit of the rotating electric machine 70, and the cost of the on-board charging device (first comparative charging device 10Y) can be reduced. In addition, since an appropriate inductance is set in the AC-DC converter 1 by the inductor L1, there is no need to control the AC-DC converter 1 with a short control period (high control frequency).

[0073] However, in the active decoupling circuit 2 of the in-vehicle charging device 10 of this embodiment, the DC side terminal T1d of the AC-DC converter 1 and the DC side terminal T5d of the inverter 5 are connected without any other passive components (for example, the DC link capacitor 6), whereas in the DC-DC converter 20 of the first comparative charging device 10Y, the DC side terminal T1d of the AC-DC converter 1 and the DC side terminal T5d of the inverter 5 are connected via the DC link capacitor 6. In the first comparative charging device 10Y, the AC component Prpl, which is a pulsating 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 driving system of the rotating electric machine 70. As a result, it becomes necessary to make the capacitance of the DC link capacitor 6 larger than that when it is used only in the rotating electric machine driving system. According to experiments and simulations by the inventors, it was found that the DC link capacitor 6 of the first comparative charging device 10Y requires approximately twice the capacity as the DC link capacitor 6 of the in-vehicle charging device 10 of this embodiment. Therefore, the in-vehicle charging device 10 of this embodiment is easier to achieve downsizing and reduction in system costs than the first comparative charging device 10Y.

[0074] In the first comparative charging device 10Y, the main contactor 11 has 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 in-vehicle charging device 10 of this embodiment, only one contact is required for the main contactor 11, which prevents the main contactor 11 from becoming large in size and the size of the in-vehicle charging device 10 from becoming large, making it easy to reduce system costs.

[0075] As described above, in the in-vehicle charging device 10 of this embodiment, when the main contactor 11 is closed and the OBC contactor 12 is open, power is converted between the DC power source 3 and the rotating electric machine 70 via the inverter 5, and when the main contactor 11 and the OBC contactor are both closed, power is converted between the external AC power source 4 and the DC power source 3 via the active decoupling circuit 2 including the AC-DC converter 1 and the inverter 5.

[0076] In many cases, a contactor is arranged between the drive device for driving the rotating electric machine 70 or the on-board charging device 10 and the DC power source 3 to cut off electrical connection when the DC power source 3 is not used. Since a large current flows through the contactor, a contactor with a high current capacity and high voltage resistance is used, and the contactor tends to be large in size. The on-board charging device 10 of this embodiment shares a part of the circuit with the drive device for driving the rotating electric machine 70, and also includes a contactor for switching the circuit. This contactor is often required to have a relatively high current capacity and voltage resistance. According to this configuration, the drive device and the on-board charging device 10 can be switched by two contactors, the first contactor (main contactor 11) and the second contactor (OBC contactor 12), so that the circuit size can be easily kept small. [Explanation of symbols]

[0077] 1: AC-DC converter, 1S: switching element, 2: active decoupling circuit, 3: DC power supply, 4: external AC power supply, 5: inverter, 5L: lower-stage switching element, 5S: switching element, 5U: upper-stage switching element, 7: coil, 7N: neutral point, 9: vehicle drive device, 10: on-board charging device, 11: main contactor (first contactor), 12: OBC contactor (second contactor), 70: rotating electric machine, Cs: output capacitor, T1d: DC side terminal, T5d: DC side terminal

Claims

1. An on-board charging device for charging a DC power supply of a vehicle drive device, the on-board charging device comprising: a rotating electric machine having multiple phase coils connected to each other at a neutral point and serving as a drive power source for wheels; an inverter that converts power between DC and multiple phase AC; and a DC power supply connected to the inverter, the on-board charging device charging the DC power supply with power supplied from an external AC power supply, an AC / DC converter that converts power between AC power on the side of the external AC power supply and a first DC power; an active decoupling circuit configured to include the inverter, the 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; a DC side terminal of the AC-DC converter and a DC side terminal of the inverter are connected without any other passive components; An on-board charging device, wherein the output capacitor is connected between the neutral point of the coil and a negative pole of a direct current.

2. a first contactor that electrically connects and disconnects the DC power source and a DC side terminal of the inverter; a second contactor that electrically disconnects the neutral point and the output capacitor; power is converted between the DC power source and the rotating electric machine via the inverter while the first contactor is closed and the second contactor is open; 2. The in-vehicle charging device according to claim 1, wherein, when the first contactor and the second contactor are both closed, power is converted between the external AC power source and the DC power source via the active decoupling circuit including the AC-DC converter and the inverter.

3. The inverter is configured to include a plurality of arms in parallel, each arm having an upper-stage switching element and a lower-stage switching element connected in series between a positive electrode and a negative electrode of a direct current, the plurality of arms corresponding to the number of phases of a multi-phase alternating current; 3. The in-vehicle charging device according to claim 1, wherein when the inverter functions as the active decoupling circuit, a plurality of the upper-stage switching elements are simultaneously switched-controlled and a plurality of the lower-stage switching elements are simultaneously switched-controlled.

4. 4. The in-vehicle charging device according to claim 3, wherein the inverter controls switching of the plurality of upper-stage switching elements and the plurality of lower-stage switching elements so that a phase of a current flowing through the output capacitor coincides with a phase of an AC current in the AC-DC converter.

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