Vehicle-mounted charging device

Abstract

A vehicle-mounted charging device is configured so as to suppress an increase in system cost, and the vehicle-mounted charging device charges a DC power source of a vehicle drive device provided with a rotating electric machine, an inverter, and the DC power source by means of power from an external AC power source using a coil of the rotating electric machine and the inverter. An in-vehicle charging device (10) is provided with: an AC / DC converter (1) that converts power between AC power on the side of an external AC power source (4) and first DC power; and an active decoupling circuit (2) configured to include an inverter (5), a multi-phase coil (7), and an output capacitor (Cs), the active decoupling circuit (2) generating second DC power for charging the DC power source (3) from the first DC power, the DC-side terminal (T1d) of the AC-DC converter and the DC-side terminal (T5d) of the inverter being connected without passing through other passive components, and the DC-side terminal (T5d) of the inverter being connected to the DC-side terminal (T5d) of the AC-DC converter and the DC-side terminal (T5d) of the inverter. The output capacitor is connected between the neutral point (7N) of the coil and the negative electrode of the direct current.

Description

Technical Field

[0001] The invention relates to a vehicle-mounted charging device. Background Art

[0002] Japanese Patent Publication No. 2022-503713 discloses an onboard charging device (onboard charger, Onboardcharger), which charges a DC power source mounted on a vehicle such as an electric vehicle or a hybrid vehicle that has a rotating electric machine as a driving force source for the wheels while being mounted on the vehicle (the reference numerals in parentheses in the background art are reference numerals of the referenced document). Figure 3 An on-vehicle charging device is illustrated in the figure, wherein a single-phase external AC power source (310) is connected to the neutral point of a three-phase coil connected in a Y shape, each arm of the AC side of an inverter (220) is connected to each of the three-phase coils, an input side terminal of a DC converter (DC / DC converter) is connected to the DC side terminal of the inverter (220), and a DC power source is connected to the output side terminal of the DC converter. The three-phase coil and the inverter (220) form an AC / DC converter (AC / DC converter) that converts a sinusoidal grid current from the external AC power source (310) into a DC power source. By switching the inverter (220), the AC / DC converter also functions as a power factor correction (PFC) circuit that corrects the power factor of the DC power converted from the AC power. The current after the AC / DC conversion generates a ripple with a frequency twice the frequency (system frequency) of the external AC power source (310). The DC converter reduces the ripple and generates a battery current for charging the DC power source. In addition, a smoothing capacitor is provided between the AC-DC converter and the DC converter.

[0003] Patent Document 1: Japanese Patent Application No. 2022-503713

[0004] Here, for example, in an on-board charger of an electric vehicle or a hybrid vehicle, as a three-phase coil, a coil (stator coil) provided in the stator of a rotating electric machine that is a driving force source of the vehicle can be used. However, such a rotating electric machine is designed to have a high power density and a small inductance. Figure 3 As exemplified in FIG. 1 , when an AC-DC converter is formed by connecting a single-phase external AC power supply to a neutral point, the peak value of the harmonic current of the system current of the external AC power supply tends to increase during AC-DC conversion.

[0005] As a method for suppressing this situation, it is possible to consider increasing the control frequency of the inverter constituting the AC-DC converter. Alternatively, in order to reduce the ripple on the DC converter side, it is possible to consider increasing the control frequency of the DC converter. Among them, when the control frequency is increased, it is also necessary to shorten the control cycle (operation frequency) of the control device that controls the inverter and the DC converter. In addition, the switching action at a high frequency accompanied by a fast control cycle increases the loss of the switching elements possessed by the inverter and the DC converter, causing a decrease in the efficiency of the on-board charging device. In addition, as a control device, it is necessary to use a microcomputer capable of high-speed operation, etc., which causes an increase in the cost of the on-board charging device. Alternatively, as another method, it is also possible to consider adding an inductor between the external AC power supply and the neutral point of the multi-phase coil. However, in this case, the cost of the on-board charging device is also increased due to the addition of the inductor. In addition, the smoothing capacitor possessed between the AC-DC converter and the DC converter also seeks a larger capacity, which is easy to cause the on-board charging device to be enlarged and the cost to increase, which is accompanied by the enlargement of the appearance. Summary of the invention

[0006] In view of the above, it is desired to configure a vehicle-mounted charging device in a manner that suppresses an increase in system cost, wherein the vehicle-mounted charging device charges a vehicle drive device having a rotating motor, an inverter, and a DC power supply using power from an external AC power supply, and the DC power supply uses the coil of the rotating motor and the inverter to charge the DC power supply.

[0007] In view of the above-mentioned on-vehicle charging device charging the DC power supply of the vehicle drive device by the power supplied from the external AC power supply, the vehicle drive device comprises: a rotating electric machine, which comprises multi-phase coils connected to each other at a neutral point and serves as a driving force source for the wheels; an inverter, which converts power between DC and multi-phase AC; and the DC power supply connected to the inverter, the on-vehicle charging device comprises: an AC-DC converter, which converts power between AC power on the side of the external AC power supply and a first DC power; and an active decoupling circuit, which comprises the inverter, the multi-phase coils and an output capacitor, and generates a second DC power for charging the DC power supply from the first DC power, the DC side terminal of the AC-DC converter and the DC side terminal of the inverter are connected without passing through other passive components, and the output capacitor is connected between the neutral point of the coil and the negative pole of the DC.

[0008] According to this structure, the AC-DC converter that requires a suitable inductance is configured to not use the driving system circuit of the rotating motor (the coil of the rotating motor and the inverter that drives the rotating motor). In the case where the on-board charging device uses the coil of the rotating motor, the inductance of the coil is small, and thus it is difficult to ensure the required performance. However, according to this structure, 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 without using the coil of the rotating motor, by using an AC-DC converter that can set a suitable inductance. In addition, since a suitable inductance can be set in the AC-DC converter, it is not necessary to control the AC-DC converter with a shorter control cycle (higher control frequency), and the loss of the switching element constituting the AC-DC converter is also easily reduced. Therefore, the system efficiency of the on-board charging device is also easily improved. In addition, a pulsating component is superimposed on the DC converted from the AC by the AC-DC converter, and therefore, a DC converter is usually configured in the later stage of the AC-DC converter via a decoupling capacitor for smoothing the pulsating component. According to this structure, the pulsation component can be reduced by an active decoupling circuit connected to the AC-DC converter instead of via such a decoupling capacitor, so it is easy to suppress the circuit scale to be small. In addition, the switching element and inductor constituting the active decoupling circuit can also serve as the inverter that drives the rotating motor and the coil of the rotating motor, and the circuit scale of the entire vehicle system is also suppressed to be small. That is, according to this structure, the vehicle-mounted charging device can be constructed in a manner that suppresses the increase in system cost. The above-mentioned vehicle-mounted charging device can charge the DC power supply of a vehicle drive device having a rotating motor, an inverter, and a DC power supply by using the coil of the rotating motor and the inverter through power from an external AC power supply.

[0009] Further features and advantages of the vehicle-mounted charging device will become apparent from the following description of exemplary and non-limiting embodiments described with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic circuit block diagram of a drive control system of a rotating electrical machine.

[0011] Figure 2 This is a circuit block diagram showing an example of an on-vehicle charging device using a drive control system of a rotating electric machine.

[0012] Figure 3 Yes Figure 2 The circuit block diagram shown is a functional block diagram of a deformation.

[0013] Figure 4 1 is a diagram showing the flow of current in the active decoupling circuit (the output capacitor is being charged (the capacitor current is positive and increasing)).

[0014] Figure 5 1 is a diagram showing the flow of current in the active decoupling circuit (the output capacitor is being charged (the capacitor current is positive and decreasing)).

[0015] Figure 6 1 is a diagram showing the flow of current in the active decoupling circuit (the output capacitor is being discharged (the capacitor current is negative and the absolute value of the capacitor current is increasing)).

[0016] Figure 7 1 is a diagram showing the flow of current in the active decoupling circuit (the output capacitor is being discharged (the capacitor current is negative and the absolute value of the capacitor current is decreasing)).

[0017] Figure 8 It is a waveform diagram showing the relationship among the grid voltage, grid current, capacitor current, and capacitor voltage.

[0018] Fig. 9 This is a waveform diagram showing pulse width modulation when controlling capacitor current.

[0019] Fig.10 1 is a circuit block diagram showing a first comparative example of an on-vehicle charging device using a drive control system of a rotating electrical machine.

[0020] Fig.11 This is a circuit block diagram showing a second comparative example of an on-vehicle charging device using a drive control system of a rotating electrical machine.

[0021] Description of Reference Numerals

[0022] 1...AC-DC converter; 1S...switching element; 2...active decoupling circuit; 3...DC power supply; 4...external AC power supply; 5...inverter; 5L...lower switching element; 5S...switching element; 5U...upper 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. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the vehicle-mounted charging device will be described with reference to the drawings. Figure 1 The circuit block diagram schematically shows the drive control system of the rotating electrical machine 70. Figure 2 The circuit block diagram of FIG. 1 shows an example of an on-vehicle charging device 10 using a drive control system of a rotating electric machine 70. The on-vehicle charging device 10 is a device that is mounted on a vehicle and is used to charge a rotating electric machine 70. Figure 1A device for charging the DC power supply 3 provided in the vehicle drive device 9 as shown. Figure 1 As shown, the vehicle drive device 9 of this embodiment includes: a rotating electric machine 70 that becomes a driving force source for wheels of a hybrid vehicle, an electric vehicle, etc., an inverter 5 that converts power between direct current and multi-phase alternating current (here, three phases), and a direct current power source 3 connected to the inverter 5. In addition, the vehicle drive device 9 may also include other driving force sources such as an internal combustion engine (not shown) in addition to the rotating electric machine 70.

[0024] like Figure 2 As shown, the onboard charging device 10 is a device that charges the DC power supply 3 of the vehicle drive device 9 with power supplied from the external AC power supply 4 (grid power supply, single-phase here), and is a so-called onboard charger. In this embodiment, the onboard charging device 10 is configured to be partially shared with the vehicle drive device 9. Specifically, the inverter 5 and the coil 7 of the rotating motor 70 are shared.

[0025] like Figure 1 As shown, the vehicle drive device 9 includes a control device 8, and the control device 8 takes the rotating electric machine 70 that will be the driving force source of the vehicle as a control object, 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 embedded permanent magnet type rotating electric machine (IPMSM: Interior Permanent Magnet Synchronous Motor) having a stator with a multi-phase (N is an arbitrary natural number, N phase, and in this embodiment, a three-phase form of N=3) coil 7 (stator coil) arranged on the stator core and a rotor with a permanent magnet arranged on the rotor core. Such a structure is well known, and in this embodiment, the stator core, stator, rotor core, rotor, permanent magnet, etc. are omitted. In this embodiment, a Y-type (star) form in which the three-phase coil 7 is short-circuited at the neutral point 7N is illustrated. However, the rotating electric machine 70 may be, for example, a form in which it is provided with two sets of three-phase coils 7 and driven by six-phase alternating current. In addition, the rotating electric machine 70 can function as a motor or a generator. When the rotating electrical machine 70 functions as a motor, the rotating electrical machine 70 is in a power running state, and when the rotating electrical machine 70 functions as a generator, the rotating electrical machine 70 is in a regeneration state.

[0026] like Figure 1As shown, the vehicle drive device 9 includes an inverter 5. The inverter 5 is connected to the AC rotating electric machine 70 and the DC power supply 3, and converts power between multi-phase AC and DC. A pair of DC side terminals (DC side terminals T5d) of the inverter 5 are connected to the positive and negative terminals of the DC power supply 3. Specifically, the terminal on the positive side of the pair of DC side terminals T5d (inverter positive terminal T5P) is connected to the positive pole of the DC power supply 3, and the terminal on the negative side of the pair of DC side terminals T5d (inverter negative terminal T5N) is connected to the negative pole of the DC power supply 3. In addition, the multi-phase AC side terminals of the inverter 5 are respectively connected to the multi-phase coils 7. In the present embodiment, the inverter 5 includes a U-phase arm, a V-phase arm, and a W-phase arm as multi-phase arms. Each arm is formed by connecting the upper switching element 5U arranged on the positive side and the lower switching element 5L arranged on the negative side in series. The midpoint of each arm, i.e., the connection point between the upper switching element 5U and the lower switching element 5L, is connected to each 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.

[0027] The DC side of the inverter 5 includes a smoothing capacitor (DC link capacitor 6) for smoothing the voltage between the positive and negative electrodes (DC link voltage Vdc). The DC side of the inverter 5 also includes a voltage sensor (DC link voltage sensor 61) for detecting the DC link voltage Vdc.

[0028] The DC power supply 3 is composed of, for example, a rechargeable secondary battery (battery) such as a lithium-ion battery, an electric double-layer capacitor, or the like. As in the present embodiment, when the rotating motor 70 is the driving force source of the vehicle, the DC power supply 3 is a high-voltage and large-capacity DC power supply, and the rated power supply voltage is, for example, 200 to 400 [V]. In most cases, the DC power supply 3 is configured so that it can be electrically connected and disconnected with respect to the inverter 5 and the rotating motor 70 by operating the main switch (ignition switch) of the vehicle, etc. For example, the DC power supply 3 is connected to the inverter 5 and the rotating motor 70 via a main contactor 11 (first contactor) composed of a relay, etc. In addition, the DC power supply 3 also has a function of detecting the input and output current (battery current Ibat: refer to Figure 3 ) of the current sensor (battery current sensor 31), detecting the terminal voltage of the DC power supply 3 (battery voltage Vbat: refer to Figure 3 ) voltage sensor (battery voltage sensor 32).

[0029] Although not shown in the figure, when the DC power source 3 is a lithium-ion battery, for example, a battery management system (BMS) is usually provided. Secondary batteries such as lithium-ion batteries are composed of a plurality of cells (battery cells). The battery management system is a battery management system that performs the following processes: (1) prevention of overcharging and overdischarging of cells; (2) prevention of overcurrent flowing into cells; (3) temperature management of cells; (4) calculation of the state of charge (SOC); (5) equalization of cell voltages; etc. The above-mentioned battery current sensor 31 and battery voltage sensor 32 can also constitute part of the battery management system.

[0030] like Figure 1 As shown, the inverter 5 is configured to have a plurality of switching elements 5S. It is preferred that the switching element 5S use power semiconductor elements such as IGBT (Insulated Gate Bipolar Transistor), Power-MOSFET (Metal Oxide Semiconductor Field Effect Transistor), SiC-MOSFET (Silicon Carbide-Metal Oxide Semiconductor FET), SiC-SIT (SiC-Static Induction Transistor), GaN-MOSFET (Gallium Nitride-MOSFET) that can operate at high frequency. In the present embodiment, the form of using FET is exemplified as the switching element 5S. In addition, in the present embodiment, in each switching element 5S, a freewheeling diode is connected in parallel with the direction from the negative electrode toward the positive electrode (the direction from the lower side toward the upper side) as the forward direction. Of course, it is also possible that in the case of using a body diode, in the case of reverse conduction of a transistor of a wide bandgap semiconductor composed of enhancement mode gallium nitride (E-GaN), etc., such a freewheeling diode is not provided.

[0031] like Figure 1 As shown, the inverter 5 is controlled by the control device 8. The control device 8 is constructed with a logic circuit such as a microcomputer as a core component. For example, the control device 8 performs current feedback control using a vector control method based on the target torque (torque command) of the rotating motor 70 provided as a request signal from other control devices such as the vehicle control device 90 as one of the upper control devices, and drives the rotating motor 70 via the inverter 5. In the vector control method, the current flowing to the coil 7 of each phase (in this embodiment, the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw: refer to Figure 2Feedback control is performed by transforming the coordinates of the direction of the magnetic field generated by the permanent magnets arranged on the rotor, i.e., the d-axis, and the q-axis in the direction orthogonal to the d-axis (the direction that advances the electrical angle of π / 2 relative to the direction of the magnetic field) into the vector components of the q-axis. The coordinate system of the coordinate transformation target is called the dq-axis orthogonal coordinate system. In addition, the operating voltage of the logic circuit elements such as microcomputers is about 3.3 to 5 volts. In this embodiment, for simplicity, the illustration is omitted, but the control signal generated by the logic circuit element is transmitted to the inverter 5 via the drive circuit. Alternatively, it can also be considered that the control device 8 includes a drive circuit.

[0032] The actual current flowing in the coil 7 of each phase of the rotating motor 70 is detected by the current sensor (motor current sensor 81), and the control device 8 obtains the detection result. In addition, the magnetic pole position (electrical angle) of the rotor of the rotating motor 70 at each moment and the rotation speed (angular velocity) of the rotor are detected by a rotation sensor 82 such as a rotary transformer and an inductive position sensor (Inductive Position Sensor), and the control device 8 obtains the detection result. The control device 8 performs 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 the cooperative action between hardware such as a microcomputer and software (program).

[0033] As described above, the rotating electric machine 70 connected to the DC power source 3 via the inverter 5 functions as a motor due to 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, it is also possible to supply mechanical energy to the rotating electric machine 70 by the power of an internal combustion engine, etc., so that the rotating electric machine 70 generates electricity, but sometimes there are few opportunities for power generation and the DC power source 3 cannot be fully charged. In addition, for an electric vehicle that only carries the rotating electric machine 70 as a driving force source, it is limited to power generation by mechanical energy from the wheels in the case of inertial driving, etc., and there are many cases where the DC power source 3 cannot be fully charged. In addition, in a hybrid vehicle, it is also possible that the energy efficiency is higher when power is supplied from the outside than when the rotating electric machine 70 generates electricity. Therefore, it is preferably configured so that the DC power source 3 can be charged by an external power source when the DC power source 3 is mounted on the vehicle.

[0034] The vehicle-mounted charging device 10 of this embodiment charges the DC power supply 3 of the vehicle drive device 9 with the power supplied from the external AC power supply 4. Figure 2As shown, the vehicle-mounted charging device 10 includes: an AC / DC converter 1 (AC / DC converter) connected to an external AC power source 4 and converting AC power from the external AC power source 4 into a first DC power; and an active decoupling circuit 2 that generates a second DC power for charging a DC power source 3 from the first DC power. Although the 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 has a function as a so-called DC converter (DC / DC converter).

[0035] For the vehicle-mounted charging device 10 of the present embodiment, the DC side terminal T1d of the AC-DC converter 1 is connected to the DC side terminal T5d of the inverter 5 without passing through other passive components (such as the DC link capacitor 6). Specifically, the DC side positive terminal T1P of the AC-DC converter 1 is connected to the inverter positive terminal T5P of the inverter 5, and the DC side negative terminal T1N of the AC-DC converter 1 is connected to the inverter negative terminal T5N of the inverter 5. In addition, the output capacitor Cs is connected between the neutral point 7N of the coil 7 and the negative pole of the DC. In addition, in the present embodiment, AC power is supplied to the vehicle-mounted charging device 10 from the external AC power supply 4 via the EMI filter FLT that reduces EMI (Electro Magnetic Interference) noise.

[0036] The AC / DC converter 1 and the active decoupling circuit 2 include a switching element ( Figure 2 The vehicle-mounted charging device 10 is composed of a plurality of switch elements (switching elements represented by reference numerals 1S and 5S in the figure), which are controlled by a control device 8 that drives and controls the rotating electric machine 70 via an inverter 5. In addition, as described later, the vehicle-mounted charging device 10 is composed of contactors (main contactor 11, OBC contactor 12 (second contactor), 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 shown in FIG. Figure 1 As described above, the control device 8 is included in the drive control system of the rotating electrical machine, and the control device 8 is also commonly used in the drive control of the rotating electrical machine 70 and the charge control of the DC power source 3 .

[0037] When charging the DC power supply 3, power is supplied to the DC power supply 3 from the external AC power supply 4. Therefore, in terms of circuit structure, the AC-DC converter 1 arranged on the side (upstream side) of the external AC power supply 4 is sometimes referred to as a front-end circuit or a first circuit, and the active decoupling circuit 2 arranged on the side (downstream side) of the DC power supply 3 is sometimes referred to as a back-end circuit or a second circuit. In the present embodiment, the AC-DC converter 1, which is a front-end circuit connected to the external AC power supply 4, and the active decoupling circuit 2, which is a back-end circuit formed by a circuit separate from the vehicle drive device 9 and arranged on the DC power supply 3 side relative to the AC-DC converter 1, constitute a drive system circuit (coil 7 and inverter 5) of the common rotating electric machine 70.

[0038] As described above, in the vehicle-mounted charging device 10 of the present 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 (e.g., the DC link capacitor 6). In other words, the first circuit and the second circuit are connected without passing through passive components such as a smoothing capacitor. For example, in the case where the first circuit and the second circuit are connected via a smoothing capacitor ( Fig.10 For the illustrated first comparative example charging device 10Y, etc., the first circuit (in this case, the AC-DC converter 1) and the second circuit (in this case, the DC converter 20) can each operate independently, and the switching element 1S of the first circuit and the switching element 5S of the second circuit do not need to switch in coordination but are independently controlled. On the other hand, in the present embodiment, the first circuit (AC-DC converter 1) and the second circuit (active decoupling circuit 2) operate in coordination. Therefore, in particular, the latter circuit, that is, the switching element 5S of the second circuit is controlled to operate in conjunction with the first circuit. For details, refer to Figure 8 etc. will be described later.

[0039] like Figure 2 As shown, the AC-DC converter 1 is configured with an inductor L1. In AC-DC conversion, a phase difference is generated between the voltage phase and the current phase due to inductive impedance and capacitive impedance, and the power factor is reduced due to the phase difference. The AC-DC converter 1 is configured with a switching element 1S, and by controlling the switching element 1S, for example, adjusting the current phase, the phase difference can be compensated to correct the power factor. That is, the AC-DC converter 1 is configured to also function as a power factor correction (PFC: power factor correction) circuit that corrects the power factor of the DC power converted from the AC power supplied by the external AC power source 4.

[0040] In the present embodiment, the AC-DC converter 1 is configured by including an inductor L1 and a full-bridge circuit using a switching element 1S. By including a full-bridge circuit, the AC-DC converter 1 can function as a bidirectional converter capable of performing AC-DC conversion and DC-AC conversion. For example, the vehicle-mounted charging device 10 can be used as a device having two functions: a function of charging the DC power supply 3 with power supplied from the external AC power supply 4, and a function of supplying AC power to a device outside the vehicle with power stored in the DC power supply 3.

[0041] In recent years, it is advocated to use the DC power supply 3 of electric vehicles and hybrid vehicles as an emergency power supply in disasters. Since the AC-DC converter 1 has a full-bridge circuit, the DC power supply 3 can be used as such an emergency power supply. Of course, it is also possible that, in the case where the use of such a DC power supply 3 is not considered, the AC-DC converter 1 is configured as a unidirectional converter that only performs AC-DC conversion. In this case, it is also possible that the AC-DC converter 1 is configured with, for example, a half-bridge circuit.

[0042] like Figure 2 As shown, 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 (disconnects and connects the AC side terminal T1a to the external AC power source 4). The grid contactor 13 is also composed of, for example, a relay. When the grid contactor 13 is closed, the grid contactor 13 becomes conductive, and the external AC power source 4 is electrically connected to the vehicle-mounted charging device 10 (AC-DC converter 1).

[0043] like Figure 2 As shown, the on-board charging device 10 includes an OBC contactor 12 that disconnects and connects the electrical connection between the neutral point 7N of the coil 7 and the output capacitor Cs. The OBC contactor 12 is also composed of, for example, a relay. If the OBC contactor 12 is closed, the OBC contactor 12 is turned on, and the neutral point 7N is connected to the negative pole of the DC via the output capacitor Cs. In addition, as described above, the drive control system of the rotating electric machine 70 and the on-board charging device 10 share the main contactor 11. When the inverter 5 functions as the on-board charging device 10, the main contactor 11 is controlled to be closed and the OBC contactor 12 is closed. That is, in a state where both the main contactor 11 and the OBC contactor 12 are closed, power is converted between the external AC power supply 4 and the DC power supply 3 via the AC-DC converter 1 and the active decoupling circuit 2 including the inverter 5.

[0044] When the inverter 5 is used for driving control of the rotating electric machine 70, the control is such that the main contactor 11 is closed and the OBC contactor 12 and the grid contactor 13 are opened. That is, in a state where the main contactor 11 is closed and the OBC contactor 12 is opened, power is converted between the DC power supply 3 and the rotating electric machine 70 via the inverter 5.

[0045] In this way, by simply changing the connection form to the coil 7 using the OBC contactor 12, a circuit capable of switching between the function of driving and controlling the rotating electric machine 70 and the function of charging the DC power supply 3 through the external AC power supply 4 can be realized. That is, the vehicle-mounted charging device 10 can be configured with a simple structure.

[0046] As described above, the vehicle-mounted charging device 10 is configured to include the AC / DC converter 1 and the active decoupling circuit 2 . Figure 3 The circuit diagram is shown in Figure 1 for easy understanding. Figure 2 The circuit block diagram is shown separately by function. The AC-DC converter 1 performs voltage boosting and adjusts the power factor of the grid current Igrid supplied from the external AC power source 4 to a value close to "1". Among them, a pulsating 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. The active decoupling circuit 2 reduces the pulsation of the second harmonic component, and supplies the second DC power with suppressed pulsation, preferably the second DC power with pulsation removed, to the DC power source 3 to charge the DC power source 3.

[0047] Here, if the AC voltage supplied from the external AC power supply 4 is set to "grid voltage Vgrid", the AC current is set to "grid current Igrid", and the respective amplitudes (the value from the center of the amplitude to the wave height, and a positive value; the same applies to "_peak" below) are set to "Vgrid_peak" and "Igrid_peak", then the grid voltage Vgrid and the grid current Igrid are expressed by the following equations (1) and (2).

[0048] [Mathematical formula 1]

[0049] V grid =V grid_peak cosωt…(1)

[0050] [Mathematical formula 2]

[0051] I grid =I grid_peak cosωt…(2)

[0052] If it is assumed that the input power Pin input from the external AC power source 4 to the AC-DC converter 1 has a power factor of "1" and is converted into the first DC power, the relationship between the input power Pin and the first DC power is expressed by the following equations (3) to (5). Equation (3) shows that the first DC power includes a DC component Pdc and an AC component Prpl. Equation (4) shows the DC component Pdc of the first DC power, and Equation (5) shows the pulsating component of the first DC power, that is, the AC component Prpl.

[0053] [Mathematical formula 3]

[0054] P in =V grid I grid ≈P dc +P rpl …(3)

[0055] [Formula 4]

[0056]

[0057] [Formula 5]

[0058]

[0059] The active decoupling circuit 2 functions so that a current corresponding to the AC component Prpl shown in the equation (5) flows in the active decoupling circuit 2 and the output power Pout output to the DC power supply 3 becomes only the DC component Pdc shown in the equation (4) (equation (6)). Therefore, as shown in the following equation (7), the active decoupling circuit 2 operates so that the power of the output capacitor Cs, that is, the capacitor power Pcs, is consistent with the AC component Prpl of the first DC power.

[0060] [Mathematical formula 6]

[0061] P out =P dc …(6)

[0062] [Formula 7]

[0063] P rpl =P cs …(7)

[0064] Since the capacitor power Pcs satisfies the relationship of the following equation (8) between the capacitor voltage Vcs and the capacitor current Ics, the capacitor power Pcs can be controlled by appropriately controlling the capacitor current Ics.

[0065] [Mathematical formula 8]

[0066] P cs =V cs Ics …(8)

[0067] Figures 4 to 7 The flow of current in the active decoupling circuit 2 is shown. In addition, Figure 8 The waveform diagram 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 Figure 8 The capacitor current command I is also shown ＊ cs. In addition, Fig. 9 The waveform diagram shows the capacitor current command I controlled by the switch through pulse width modulation control ＊ cs, capacitor current Ics and switching pulses.

[0068] Figure 4 and Figure 5 The capacitor current Ics flowing to the output capacitor Cs is shown as Figure 3 The direction of the arrow shown is a positive value and the current flows when the output capacitor Cs is charged, which is equivalent to Figure 8 and Fig. 9 The flow of current during the period described as "Charging" in FIG. Figure 6 and Figure 7 The capacitor current Ics flowing to the output capacitor Cs is negative and the current flow when the output capacitor Cs is discharged is equivalent to Figure 8 and Fig. 9 The flow of current during the period described as "Discharging" in FIG.

[0069] As described above, the inductance of the coil 7 of the rotating electric machine 70 is small, and therefore, the inductor (coil 7) is used not for storing energy but for passing current in the active decoupling circuit 2. In addition, in the vehicle-mounted charging device 10 of the present embodiment, the capacitor current Ics is used as a discontinuous current obtained by pulse width modulation rather than as a so-called continuous current, thereby realizing the decoupling effect obtained by the active decoupling circuit 2.

[0070] As described above, the inverter 5 is configured to have an arm having an upper switching element 5U and a lower switching element 5L connected in series in a manner of multiple arms connected in parallel between the positive and negative poles of the DC corresponding to the number of phases of the multi-phase AC. In the present embodiment, the inverter 5 is configured to have three arms. When the inverter 5 functions as an active decoupling circuit 2, multiple upper switching elements 5U are simultaneously switched and controlled, and multiple lower switching elements 5L are simultaneously switched. That is, the inverter 5 having a multi-phase arm corresponding to the multi-phase AC can be used as an inverter (switching circuit) having a single-phase arm. The current is dispersed and flows in multiple arms, so even if the inverter 5 is used as part of the vehicle-mounted charging device 10, it is easy to suppress the consumption of the inverter 5.

[0071] In addition, currents of almost the same magnitude flow through each of the multi-phase coils 7 except for individual differences and errors. Therefore, even if the coils 7 are also used for the on-board charging device 10, the rotor generates almost no torque. Since the charging of the DC power supply 3 is carried out when the vehicle is stopped, it is not desirable for the rotor to generate torque. For example, it is also considered to cut off the power transmission from the rotor to the wheel by a clutch, etc., or to limit the rotation of the output member connected to the wheel and the rotation of the rotor by a so-called parking brake, etc. However, these situations also lead to the complication of the mechanism of the vehicle drive device 9, or cause mechanical loads to be generated on the gears of the vehicle drive device 9. In the present embodiment, the control is such that the rotor does not generate torque, so the on-board charging device 10 can be appropriately constructed in a manner that almost no mechanical load is generated on the gears of the vehicle drive device 9, etc.

[0072] Fig. 9 The waveform diagram of FIG. 1 shows the modulation pulse of the pulse width modulation of the upper switching element 5U and the lower switching element 5L when controlling the capacitor current Ics. The sinusoidal waveform is the capacitor current command I ＊ cs, based on the capacitor current command I ＊ cs, a modulation pulse is generated by the control device 8. Therefore, the actual capacitor current Ics becomes a triangular waveform. Fig. 9 As can be seen, the inverter 5 is controlled by modulating pulses to be in three states: a first state in which all upper switch elements 5U are turned on (ON) and all lower switch elements 5L are turned off (OFF), a second state in which all upper switch elements 5U are turned off and all lower switch elements 5L are turned on, and a third state in which all upper switch elements 5U and all lower switch elements 5L are turned off. In the third state, all switch elements 5S of the inverter 5 are turned off.

[0073] Figure 4 The capacitor current Ics flowing to the output capacitor Cs is shown as Figure 2 and Figure 3The direction of the arrow shown is the positive direction, and the current flows when the output capacitor Cs is charged by increasing the current value. Figure 8 and Fig. 9 The capacitor current Ics in the period described as “Charging” in the waveform diagram shown in FIG. 1 is determined by the capacitor current command I ＊ The period during which the amplitude center of cs increases toward the wave height (peak value). 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 by charging 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.

[0074] Figure 5 The flow of current when the capacitor current Ics is positive and decreasing and the output capacitor Cs is charged is shown. Figure 8 and Fig. 9 The capacitor current Ics in the period described as “Charging” in the waveform diagram shown in FIG. 1 is determined by the capacitor current command I ＊ The period during which the wave height (peak value) of cs decreases toward the center of the amplitude. The switching element 5S of the inverter is controlled to be in the third state. The capacitor current Ics passes through the freewheeling diode connected in parallel with the lower switching element 5L or passes through the lower switching element 5L (using the body diode or the reverse conduction of the E-GaN transistor) and decreases while flowing back between the output capacitor Cs.

[0075] That is, in the "Charging" stage, the lower switching element 5L is controlled to be always off, and the upper switching element 5U is switched by pulse width modulation control.

[0076] Figure 7 The capacitor current Ics is negative and the absolute value of the capacitor current Ics decreases, and the current flows when the output capacitor Cs is discharged. Figure 8 and Fig. 9 The absolute value of the capacitor current Ics in the period described as “disharging” in the waveform diagram shown in FIG. 1 is determined from the capacitor current command I ＊The period during which the wave height (bottom) of cs decreases toward the center of the amplitude. The switching element 5S of the inverter is controlled to become 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 freewheeling diode connected in parallel with the upper switching element 5U or through the lower switching element 5L (using the body diode, the reverse conduction of the E-GaN transistor) . That is, the AC component Prpl of the first DC power is reduced due to the charge discharged from 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.

[0077] Figure 6 The capacitor current Ics is negative and the absolute value of the capacitor current Ics increases to discharge the output capacitor Cs. Figure 8 and Fig. 9 In the period described as “Discharging” in the waveform diagram shown in FIG. 1 , the absolute value of the capacitor current Ics is determined by the capacitor current command I ＊ The period during which the amplitude of cs increases from the center toward the peak (bottom). The switching element 5S of the inverter is controlled to be in the second state. The absolute value of the capacitor current Ics increases while flowing back between the lower switching element 5L and the output capacitor Cs.

[0078] That is, in the "disharging" stage, contrary to the "charging" stage, the upper switching element 5U is controlled to be always off, and the lower switching element 5L is switched by pulse width modulation control.

[0079] In addition, if Figure 8 As shown, the capacitor current command I ＊ The phase of cs is consistent with the phase of the grid voltage Vgrid and the phase of the grid current Igrid. The grid voltage Vgrid and the grid current Igrid are expressed by the above equations (1) and (2), and the AC component Prpl of the input power Pin is expressed by the above equation (5). Therefore, the capacitor current command I ＊ The amplitude of cs is set to I ＊ The capacitor current command I is expressed by the following equation (9): ＊ cs. The phase of the capacitor voltage Vcs is delayed by π / 2 with respect to the capacitor current Ics. The amplitude of the capacitor voltage Vcs is denoted by Vcs_peak, and the capacitor voltage Vcs is expressed by the following equation (10).

[0080] [Mathematical formula 9]

[0081] I * cs =I* cs_peak cos2ωt…(9)

[0082] [Formula 10]

[0083]

[0084] As described above, the inverter 5 performs switching control on the plurality of upper switching elements 5U and the plurality of lower switching elements 5L so that the phase of the current flowing in 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 harmonic components of the AC in the AC-DC converter 1 by causing the AC harmonic components to flow in the output capacitor Cs. By aligning the phase of the current flowing in the output capacitor Cs with the phase of the AC current in the AC-DC converter 1, the attenuation effect can be improved.

[0085] In addition, as described above, in this embodiment, it is necessary to allow a current (capacitor current Ics) corresponding to the pulsating component, that is, the AC component Prpl of the first DC power to flow to the active decoupling circuit 2. That is, it is necessary to implement the above-mentioned "charging" current loop and "discharging" current loop with respect to the output capacitor Cs. Therefore, the capacitor current command I ＊ cs is set in consideration of its magnitude relationship with the output voltage (=battery voltage Vbat) of the DC power supply 3 .

[0086] In order to realize the "Charging" current loop ( Figure 4 ), "Discharging" current loop ( Figure 7 ), the capacitor voltage Vcs needs to be a voltage lower than the battery voltage Vbat. In addition, since the capacitor voltage Vcs generates pulsation equivalent to the AC component Prpl of the first DC power, 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, when the amplitude of the AC component "Vrpl" of the voltage in the first DC power is set to Vrpl_peak, the command value of the capacitor voltage Vcs, that is, the capacitor voltage command V ＊ The amplitude of cs is "V ＊ cs_peak" satisfies the following equation (11).

[0087] [Mathematical formula 11]

[0088] V * cs_peak <V bat -V rpl_peak …(11)

[0089] In addition, as the DC power supply 3 is charged, the battery voltage Vbat increases. Therefore, if the capacitor voltage command V ＊ If cs is constant, the difference between the capacitor voltage Vcs and the battery voltage Vbat becomes larger, the capacitor current Ics increases, and the loss also becomes larger. Therefore, it is preferred that the capacitor voltage Vcs satisfies equation (11) and increases as the battery voltage Vbat increases. That is, it is preferred that the capacitor voltage command V ＊ cs is set so as to satisfy the expression (11) and increase as the battery voltage Vbat increases.

[0090] Hereinafter, the advantages of the vehicle-mounted charger 10 will be described with reference to a comparative example. In the comparative example, the EMI filter FLT is omitted for simplicity. Fig.10 The circuit block diagram shows a first comparative example (first comparative example charging device 10Y) of a vehicle-mounted charging device 10 that utilizes a drive control system of a rotating electric machine 70. Similar to the vehicle-mounted charging device 10 of the present embodiment, the first comparative example charging device 10Y also charges the DC power supply 3 of the vehicle drive device 9 by the power supplied from the external AC power supply 4. Fig.10 As shown, the first comparative example charging device 10Y comprises: an AC / DC converter 1 (AC / DC converter) connected to an external AC power source 4 to convert AC power from the external AC power source 4 into a first DC power; and a DC converter 20 (DC / DC converter) to convert the first DC power obtained by the AC / DC converter 1 into a second DC power.

[0091] In the first comparative example charging device 10Y, the AC-DC converter 1 disposed on the side (upstream side) of the external AC power source 4 can also be referred to as a front-end circuit or a first circuit, and the DC converter 20 disposed on the side (downstream side) of the DC power source 3 can be referred to as a back-end circuit or a second circuit. In addition, in the first comparative example charging device 10Y, the front-end circuit connected to the external AC power source 4, that is, the AC-DC converter 1, is also composed of a circuit formed separately from the vehicle drive device 9, and the back-end circuit, that is, the DC converter 20 disposed on the side of the DC power source 3 relative to the AC-DC converter 1, is composed of a common drive system circuit (coil 7 and inverter 5) of the rotating electric machine 70.

[0092] Hereinafter, the configuration of the first comparative example charging device 10Y will be described. The configuration of the AC / DC converter 1 is the same as that of the AC / DC converter 1 of the above-mentioned vehicle-mounted charging device 10, and a detailed description thereof will be omitted.

[0093] Similar to the active decoupling circuit 2 of the vehicle-mounted charging device 10, the DC converter 20 also includes an inverter 5, a multi-phase coil 7, an output capacitor Cs, and an OBC contactor 12. In the active decoupling circuit 2, 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), whereas in the DC converter 20 of the first comparative example 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 through the DC link capacitor 6. In addition, 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 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 .

[0094] In addition, for the first comparative example charging device 10Y, the main contactor 11 selectively connects the positive electrode of the inverter 5 (the inverter positive terminal T5P) and the positive electrode of the output of the DC converter 20 (the positive terminal of the output capacitor Cs, the neutral point 7N in the state where the OBC contactor 12 is closed) with respect to the positive electrode of the DC power supply 3. That is, the main contactor 11 has two contacts, the main contactor first contact 11a and the main contactor second contact 11b. When the inverter 5 functions as the on-vehicle charging device (the first comparative example 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 in the drive 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 supply 3 via the main contactor 11. Furthermore, when the vehicle is stopped or when the power supply to the rotary electric machine 70 needs to be cut off due to an abnormality or the like, both the main contactor first contact 11 a and the main contactor second contact 11 b can be opened.

[0095] Fig.11The circuit block diagram shows a second comparative example (second comparative example charging device 10X) of the vehicle-mounted charging device 10 that utilizes the drive control system of the rotating electric machine 70. Like the vehicle-mounted 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 supply 3 of the vehicle drive device 9 by the power supplied from the external AC power supply 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 converter (comparative example DC converter 200). Among them, in the first comparative example charging device 10Y, the drive system circuit of the rotating electric machine 70 is shared with the DC converter 20, but in the second comparative example charging device 10X, the drive system circuit of the rotating electric machine 70 is shared with the AC-DC converter (comparative example AC-DC converter 100). The comparative example AC-DC converter 100 is composed of an inverter 5, a multi-phase coil 7, a single-phase arm 105 connected in parallel to the inverter 5, and an inductor L1 (first inductor). The multi-phase coil 7 is short-circuited at a neutral point 7N, and the inductor L1 (first inductor) and the 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 constituting the inverter 5 are connected in parallel to form one arm, and form a full-bridge circuit together with the single-phase arm 105.

[0096] In the second comparative example charging device 10X, the DC converter (comparative example DC converter 200) is independently formed without sharing the drive system circuit of the rotating electrical machine 70. The comparative example DC converter 200 is a step-down DC converter having an arm having a switching element connected in series in a complementary switching control manner and a second inductor L2 connected to the midpoint of the arm. Alternatively, the comparative example DC converter 200 may be a step-up converter or a step-up / step-down converter.

[0097] The second comparative example charging device 10X also includes the main contactor 11 and the grid contactor 13 that are the same as the first comparative example charging device 10Y of the vehicle-mounted charging device 10. In addition, the second comparative example charging device 10X also includes an OBC contactor 12 that selectively connects the comparative example AC-DC converter 100 (inverter 5) to the DC power source 3 or connects the comparative example AC-DC converter 100 (inverter 5) to the comparative example DC converter 200. The OBC contactor 12 includes two contacts, a first OBC contactor contactor 12a and a second OBC contactor contactor 12b. When the inverter 5 functions as the vehicle-mounted charging device (the second comparative example charging device 10X), the second OBC contactor contactor 12b is closed and the first OBC contactor contactor 12a is opened. When the inverter 5 is used for driving control of the rotating electrical machine 70 , the OBC contactor first contact 12 a is closed, the OBC contactor second contact 12 b is opened, and the inverter positive terminal T5P of the inverter 5 is connected to the DC power supply 3 via the OBC contactor 12 and the main contactor 11 .

[0098] The rotating electric machine that is the driving force source of the vehicle is designed to have a high power density and a small inductance. Therefore, when an external AC power source 4 is connected to the neutral point 7N to form an AC-DC converter 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 increase during AC-DC conversion.

[0099] As a method for suppressing the above-mentioned trend, it is conceivable to increase the control frequency of the inverter 5 and the comparative DC converter 200 included in the comparative example AC-DC converter 100. In the case of increasing their control frequencies, it is also necessary to shorten the control cycle (control frequency) of the control device 8. The high-frequency switching action increases the loss of the switching elements possessed by the comparative example AC-DC converter 100 (inverter 5) and the comparative example DC converter 200, causing a decrease in the efficiency of the second comparative example charging device 10X. In addition, as the control device 8, it is necessary to use a microcomputer capable of high-speed operation, etc., which causes an increase in the cost of the second comparative example charging device 10X. In view of this, in the second comparative example charging device 10X, although the coil 7 is used, in order to supplement the insufficient inductance in the coil 7, an inductor L1 is configured between the external AC power supply 4 and the neutral point 7N of the multi-phase coil 7 to ensure the required inductance. In the second comparative example charging device 10X, an inductor (second inductor L2 ) is also arranged in the comparative example DC converter 200 . Compared with the first comparative example charging device 10Y and the vehicle-mounted charging device 10 of the present embodiment, the number of inductors is increased, and the system cost is likely to increase.

[0100] In view of this, the first comparative example charging device 10Y is configured to suppress the increase in system cost. Specifically, the AC-DC converter 1 that requires appropriate inductance in the AC-DC converter and the DC converter that constitute the charging device is configured to not use the drive system circuit of the rotating motor 70 (the coil 7 of the rotating motor 70 and the inverter 5 that drives the rotating motor 70). That is, the first comparative example charging device 10Y sets the AC-DC converter 1 with appropriate inductance by using the inductor L1, and can constitute an AC-DC converter 1 that can perform AC-DC conversion while ensuring sufficient performance such as the power factor correction function. In addition, the DC converter 20 that does not require high inductance is configured to share the drive system circuit of the rotating motor 70, which can reduce the cost of the vehicle-mounted charging device (the first comparative example charging device 10Y). In addition, by setting the appropriate inductance for the AC-DC converter 1 through the inductor L1, it is also unnecessary to control the AC-DC converter 1 with a shorter control cycle (higher control frequency).

[0101] Among them, in the active decoupling circuit 2 of the vehicle-mounted charging device 10 of the present 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), while in the DC converter 20 of the first comparative example 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 through the DC link capacitor 6. In the first comparative example charging device 10Y, the pulsating component of the first DC power, that is, the AC component Prpl is reduced by the smoothing effect of the DC link capacitor 6. Therefore, the DC link capacitor 6 seeks a higher capacity than that of the DC link capacitor 6 that functions as a smoothing capacitor in the drive system of the rotating electric machine 70. As a result, the electrostatic capacitance of the DC link capacitor 6 needs to be larger than that in the case of using it only in the rotating electric machine drive system. According to the experiments and simulations of the inventors, it is known that the DC link capacitor 6 of the first comparative example charging device 10Y needs to have a capacity of about twice that of the DC link capacitor 6 of the vehicle-mounted charging device 10 of the present embodiment. Therefore, the vehicle-mounted charger 10 of the present embodiment can easily achieve miniaturization and reduction in system cost compared to the charger 10Y of the first comparative example.

[0102] In addition, in the first comparative example charging device 10Y, the main contactor 11 has two contacts. A large current flows through both the first contact 11a and the second contact 11b of the main contactor, and therefore, the size of the main contactor 11 tends to be relatively large. In the vehicle-mounted charging device 10 of this embodiment, the main contactor 11 only needs one contact, and therefore, the main contactor 11 is prevented from becoming larger in size, and the device scale of the vehicle-mounted charging device 10 is prevented from becoming larger, and the system cost is easily reduced.

[0103] As described above, in the vehicle-mounted charging device 10 of the present embodiment, when the main contactor 11 is closed and the OBC contactor 12 is open, power is converted between the DC power supply 3 and the rotating electric machine 70 via the inverter 5, and when both the main contactor 11 and the OBC contactor are closed, power is converted between the external AC power supply 4 and the DC power supply 3 via the AC-DC converter 1 and the active decoupling circuit 2 including the inverter 5.

[0104] In order to cut off the electrical connection when the DC power supply 3 is not in use, in most cases, a contactor is arranged between the drive device for driving the rotating motor 70, the on-board charging device 10 and the DC power supply 3. A large current flows in the contactor, so the contactor uses a structure with high current capacity and withstand voltage, and has a tendency to become larger in size. The on-board charging device 10 of the present embodiment also includes: a drive device for driving the rotating motor 70; and a contactor that also serves as a part of the circuit and is used to switch the circuit. The contactor also requires a structure with relatively high current capacity and withstand voltage. According to this structure, the drive device and the on-board charging device 10 can be switched through the two contactors, the first contactor (main contactor 11) and the second contactor (OBC contactor 12), so it is easy to suppress the circuit scale to a small size.

Claims

1. An on-vehicle charging device that charges a DC power supply of a vehicle drive device by power supplied from an external AC power supply, the vehicle drive device comprising: a rotating electric machine having multi-phase coils connected to each other at a neutral point and serving as a driving force source for wheels; an inverter that converts power between DC and multi-phase AC; and the DC power supply connected to the inverter. The vehicle-mounted charging device is characterized in that it comprises: an AC-DC converter that converts power between AC power on the external AC power source side and first DC power; and an active decoupling circuit including the inverter, the multi-phase coils, and an output capacitor, and generating a second DC power for charging the DC power source from the first DC power, The DC side terminal of the AC-DC converter is connected to the DC side terminal of the inverter without passing through other passive components, The output capacitor is connected between the neutral point of the coil and a negative pole of a direct current.

2. The vehicle-mounted charging device according to claim 1, characterized in that: have: a first contactor that opens and closes the electrical connection between the DC power supply and the DC side terminal of the inverter; and a second contactor that disconnects and connects the electrical connection between the neutral point and the output capacitor, In a state where the first contactor is closed and the second contactor is open, electric power is converted between the DC power supply and the rotating electric machine via the inverter. In a state where both the first contactor and the second contactor are closed, electric 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. The vehicle-mounted charging device according to claim 1 or 2, characterized in that: The inverter is configured to include a plurality of arms formed by connecting upper switching elements and lower switching elements in series between the positive electrode of the direct current and the negative electrode in accordance with the number of phases of the multi-phase alternating current, and to connect the plurality of arms in parallel. When the inverter functions as the active decoupling circuit, the plurality of upper switching elements are simultaneously switched and controlled, and the plurality of lower switching elements are simultaneously switched and controlled.

4. The vehicle-mounted charging device according to claim 3, characterized in that: The inverter controls switching of the plurality of upper switching elements and the plurality of lower switching elements so that the phase of the current flowing through the output capacitor matches the phase of the AC current in the AC-DC converter.

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