On-vehicle charging apparatus

Abstract

To configure, with higher safety, an on-vehicle charging apparatus that charges an on-vehicle DC power source with power from an external AC power source by using coils and an inverter of an on-vehicle rotary electric machine, while preventing an increase in system cost.SOLUTION: An on-vehicle charging apparatus 10 comprises a first circuit 1 that converts power between AC power and first DC power, and a second circuit 2 that generates second DC power from the first DC power. The second circuit 2 is a chopper circuit formed by including a switching circuit formed by using an inverter 5, a choke coil formed by using a coil 7, and an output capacitor Cs connected with a neutral point 7N. The first circuit 1 is a dual active bridge circuit formed by including a transformer T, a primary-side bridge circuit 111, and a secondary-side bridge circuit 112. The primary-side bridge circuit 111 is formed of a bi-directional switching element.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 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 (reference symbols in parentheses in the background art are those of the referenced document). FIG. 3 of this document illustrates an onboard charging device in which an 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 AC side arm of an inverter (220), an input side terminal of a DC / DC converter is connected to a DC side terminal of the inverter (220), and a DC power source is connected to an output side terminal of the DC / DC converter. The three-phase coils and the inverter (220) form an AC / DC converter that converts a sine wave grid current from the external AC power source (310) into DC. By controlling the switching of the inverter (220), the AC-DC converter also functions as a power factor correction (PFC) circuit that improves the power factor of the DC power converted from the AC power. A ripple occurs in the current after the AC-DC conversion, the frequency of which is twice the frequency (system frequency) of the external AC power source (310). The DC-DC converter reduces this ripple and generates a battery current for charging the DC power source. [Prior art documents] [Patent documents]

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

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

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

[0006] In addition, in a configuration in which the external AC power supply and the DC power supply are not electrically independent from each other, a relatively high leakage current from the external AC power supply may flow to the common ground. Since a user or the like may be present near the vehicle while the DC power supply is being charged, it is preferable to take such leakage current into consideration. In addition, in a configuration in which the external AC power supply and the DC power supply are not electrically independent from each other, in the event of a short circuit or the like occurring in the external AC power supply, a large short circuit current may flow to the DC power supply and the in-vehicle device connected to the DC power supply.

[0007] In view of the above background, it is desirable to configure an on-board charging device that uses the coil and inverter of an on-board rotating electric machine to charge an on-board DC power supply with power from an external AC power supply, while providing greater safety and suppressing increases in system costs. [Means for solving the problem]

[0008] In view of the above, an on-board charging device is mounted on a vehicle including a rotating electric machine having coils of multiple phases connected to each other at a neutral point, an inverter that converts power between DC and multiple phase AC, and a DC power source connected to the rotating electric machine via the inverter, and charges the DC power source with power supplied from an external AC power source, the on-board charging device including a first circuit that converts power between AC power on the side of the external AC power source and a first DC power, and a second circuit that generates second DC power from the first DC power for charging the DC power source, the second circuit being a chopper circuit including a switching circuit configured using the inverter, a choke coil configured using the coils of the multiple phases, and an output capacitor connected to the neutral point of the coils of the multiple phases, the first circuit being a dual active bridge circuit including a transformer having a primary coil and a secondary coil, a primary bridge circuit connected to the primary coil, and a secondary bridge circuit connected to the secondary coil, and the primary bridge circuit is configured with a bidirectional switching element.

[0009] According to this configuration, an inverter and a coil are used in a second circuit that converts power between a first DC power and a second DC power, instead of a first circuit that converts power between an AC power and a first DC power. A coil is used in a choke coil of a second circuit that requires a lower inductance than a coil of a rotating electric machine, instead of a first circuit that requires a larger inductance than a coil of a rotating electric machine. Therefore, it is less necessary to take measures such as adding an inductor or increasing the control frequency of the vehicle-mounted charging device due to the inductance that is insufficient in the coil of a rotating electric machine, and an increase in system costs can be suppressed. In addition, since the primary side bridge circuit of the first circuit is composed of bidirectional switching elements, the primary side bridge circuit can be switched by current control using an inductor, rather than voltage control using a capacitor. Since a capacitor with a large capacity tends to be large in size, it is easy to suppress the size of the vehicle-mounted charging device. In addition, a bidirectional switching element easily realizes soft switching accompanied by zero current switching that makes the current flowing through the switching element zero during switching. Therefore, it is easy to reduce losses in the on-board charging device and to reduce system costs. Furthermore, by providing a transformer in the first circuit, the DC power supply and the external AC power supply are insulated. Therefore, it is easy to ensure the safety of the user against leakage current from the external AC power supply. Furthermore, when a short circuit or the like occurs in the external AC power supply, it is possible to reduce the possibility that a large short-circuit current will flow to the DC power supply and the on-board device connected to the DC power supply. Thus, according to this configuration, it is possible to configure an on-board charging device that uses the coil and inverter of the on-board rotating electric machine to charge the on-board DC power supply with power from the external AC power supply, with higher safety and suppressing increases in system costs.

[0010] 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]

[0011] [Figure 1]Schematic circuit block diagram of a drive control system for a rotating electric machine [Diagram 2] A circuit block diagram showing a first example of an on-board charging device using a drive control system for a rotating electric machine. [Diagram 3] A circuit block diagram showing a second example of an on-board charging device using a drive control system for a rotating electric machine. [Figure 4] A circuit block diagram showing a third example of an on-board charging device using a drive control system for a rotating electric machine. [Diagram 5] A circuit block diagram showing a fourth example of an on-board charging device using a drive control system for a rotating electric machine. [Figure 6] A circuit block diagram showing a fifth example of an on-board charging device using a drive control system for a rotating electric machine. [Figure 7] Circuit block diagram showing a comparative example of an on-board charging device using a drive control system for a rotating electric machine DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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 a first 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 phases (here, three phases) of AC, 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.

[0013] As shown in Fig. 2, the vehicle-mounted charging device 10 is a device that charges a DC power source 3 of a vehicle drive device 9 with power supplied from an external AC power source 4 (grid power source), and is a device that is so-called an onboard charger. In a first example, 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.

[0014] As shown in FIG. 1, a vehicle drive device 9 includes a control device 80 that controls a rotating electric machine 70 that serves as a driving force source for a vehicle, and the control device 80 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, in a form in which two sets of three-phase coils 7 are arranged and driven by six-phase alternating current. The rotating electric machine 70 can function both as an electric motor and as 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.

[0015] 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 of the inverter 5 are connected to a positive terminal and a negative terminal 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 an upper-stage switching element 5U arranged on the positive side and a lower-stage switching element 5L arranged on the negative side in series. The midpoint of each arm, that is, the connection point between the upper-stage switching element 5U and the lower-stage 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.

[0016] A smoothing capacitor (DC link capacitor 6) that smoothes the voltage (DC link voltage) between the positive and negative poles 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 is also provided on the DC side of the inverter 5.

[0017] 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 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 the input / output current to and from the DC power source 3, and a voltage sensor (battery voltage sensor 32) that detects the terminal voltage of the DC power source 3. The relay may be a mechanical relay or a semiconductor relay (solid state relay). The same applies to other contactors below.

[0018] 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.

[0019] 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 form in which a FET is used as the switching element 5S is illustrated. 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 form of freewheel diode may not be provided.

[0020] As shown in FIG. 1, the inverter 5 is controlled by a control device 80. The control device 80 is constructed with a logic circuit such as a microcomputer as a core member. For example, the control device 80 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 80 may be considered to include the drive circuit.

[0021] 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 80 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 80 acquires the detection results. The control device 80 executes current feedback control using the detection results of the motor current sensor 81 and the rotation sensor 82. The control device 80 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).

[0022] 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.

[0023] When the DC power supply 3 is charged by an external power supply, it is preferable that an on-board charging device is installed in the vehicle. In many cases, the external power supply is AC because it receives power from a commercial power supply. For this reason, the on-board charging device is configured to have a power conversion function from AC to DC. As a circuit for converting power from AC to DC, an AC-DC converter equipped with an inductor and a bridge circuit composed of switching elements is known. Although the conversion from AC to DC can be realized by a rectifier circuit using a rectifier element such as a diode, it is preferable that the power conversion is performed in a state where the power factor defined by the phase of the AC voltage and current is close to "1". For this reason, the AC-DC converter often includes a bridge circuit using switching elements so as to realize a power factor correction circuit.

[0024] An on-board charging device equipped with such a power conversion circuit tends to have a large circuit scale, but there are fewer opportunities to charge the DC power source 3 compared to driving the wheels. Therefore, it is preferable that the on-board charging device has a small-scale configuration. When charging the DC power source 3 from an external power source, the vehicle is stopped (parked). Therefore, the inverter 5 formed of a switching element and the coil 7 of the rotating electric machine 70 having inductance are not used to drive the wheels when charging the DC power source 3 from an external power source. Therefore, it is conceivable to use the inverter 5 and the coil 7 to configure an on-board charging device.

[0025] The vehicle-mounted charging device 10 of this embodiment charges a DC power source 3 of a vehicle drive device 9 with power supplied from an external AC power source 4. As shown in FIG. 2, the vehicle-mounted charging device 10 includes a first circuit 1 that converts power between AC power on the side of the external AC power source 4 and a first DC power, and a second circuit 2 that generates a second DC power from the first DC power to charge the DC power source 3. The first circuit 1 is a so-called AC / DC converter, and the second circuit 2 is a so-called DC / DC converter. As shown in FIG. 2, an LC filter circuit 1f composed of a filter inductor Lf and a filter capacitor Cf is provided at a connection portion (between a primary side bridge circuit 111 described later and the external AC power source 4) of the first circuit 1. Note that a configuration in which the LC filter circuit 1f is not provided is not prohibited.

[0026] The first circuit 1 is a dual active bridge (DAB) circuit including a transformer T having a primary coil T1 and a secondary coil T2, a primary bridge circuit 111 connected to the primary coil T1, and a secondary bridge circuit 112 connected to the secondary coil T2. It can also be said that the first circuit 1 includes a primary circuit 1a and a secondary circuit 1b insulated by the transformer T. The primary circuit 1a includes a primary coil T1 and a primary bridge circuit 111. The primary bridge circuit 111 of the first example is a full bridge (H bridge) in which two arms, each of which has two switching elements 11S connected in series, are connected in parallel, and the upper switching element 11S is connected to one end of the external AC power source 4 via a grid contactor 13. The lower switching element 11S is connected to the other end of the external AC power source 4. The grid contactor 13 is, for example, a relay or the like. When the external AC power supply 4 is connected to the in-vehicle charging device 10 to charge the DC power supply 3, the grid contactor 13 closes and the contacts are turned on, electrically connecting the external AC power supply 4 and the primary-side bridge circuit 111. The primary-side coil T1 is connected between the midpoint of one arm (the connection point between the upper-side switching element 11S and the lower-side switching element 11S) and the midpoint of the other arm.

[0027] The secondary circuit 1b includes a secondary coil T2, a secondary bridge circuit 112, and a secondary inductor Ls. In the first example, and in the second, third, fourth, and fifth examples described below, the secondary bridge circuit 112 is a full bridge in which two arms, each of which has two switching elements 12S connected in series, are connected in parallel. In each arm, the secondary coil T2 is connected via the secondary inductor Ls between the connection point between the upper switching element 12S and the lower switching element 12S.

[0028] As shown in FIG. 2, the primary bridge circuit 111 is composed of bidirectional switching devices. That is, the switching device 11S of the primary bridge circuit 111 is a bidirectional switching device. The bidirectional switching device is an element that can pass current in both directions, and has the same withstand voltage for both positive and negative voltages. For this reason, it is easy to construct a current-controlled AC-DC converter using an inductor (filter inductor Lf) as the primary circuit 1a in the first circuit 1. This inductor acts to pass a constant current. A voltage-controlled AC-DC converter requires a large-capacity capacitor, but a current-controlled AC-DC converter does not require a large-capacity capacitor, which reduces component costs and prevents the device from becoming large in size. The filter capacitor Cf is a small-capacity capacitor. In addition, between the first circuit 1 and the second circuit 2, the DC link capacitor 6 of the vehicle drive device 9 is also used as a smoothing capacitor that smoothes the DC voltage output from the first circuit 1. When the DC link capacitor 6 is also used for the on-board charging device 10, a larger capacity may be required than the capacity required for the vehicle drive device 9. However, if the primary side bridge circuit 111 is configured with bidirectional switching elements and a current-controlled AC-DC converter is constructed, the capacity of the DC link capacitor 6 does not need to be large, and the system can be made more compact.

[0029] Furthermore, the bidirectional switching element can easily realize soft switching accompanied by zero current switching, which makes the current flowing through the switching element zero during switching. Therefore, it is easy to reduce the loss of the in-vehicle charging device 10 and the system cost.

[0030] In AC-DC conversion, a phase difference occurs between the voltage phase and the current phase due to inductive impedance and capacitive impedance, and this phase difference reduces the power factor. The first circuit 1 is configured to include switching elements 11S and 12S, and by controlling the switching elements 11S and 12S, for example, the current phase is adjusted and the phase difference between the voltage and the current is compensated for, thereby improving the power factor. In other words, the first circuit 1 is configured to also function as a power factor correction (PFC) circuit that improves the power factor of DC power converted from AC power supplied from the external AC power source 4.

[0031] The second circuit 2 is a chopper circuit including a switching circuit using an inverter 5, a choke coil using a coil 7 of multiple phases, and an output capacitor Cs connected to a neutral point 7N of the coil 7 of multiple phases. As shown in FIG. 1 and FIG. 2, the inverter 5 is configured with a number of arms for one phase in which an upper-stage switching element 5U and a lower-stage switching element 5L are connected in series, the number of arms corresponding to the number of phases of the multiple-phase AC (here, three arms corresponding to three phases) connected in parallel. When the inverter 5 functions as a switching circuit of a chopper circuit, all the upper-stage switching elements 5U of the arms of the multiple phases are simultaneously and similarly controlled to be turned on and off, and all the lower-stage switching elements 5L of the arms of the multiple phases are simultaneously and similarly controlled to be turned on and off. Therefore, the inverter 5 having multiple arms apparently functions as a switching circuit formed by one arm in which an upper-stage switching element 5U and a lower-stage switching element 5L are connected in series.

[0032] One end of each of the coils 7 of the multiple phases is connected to the midpoint of the arm corresponding to the respective phase (the connection point between the upper-stage switching element 5U and the lower-stage switching element 5L), and the other end is connected to the neutral point 7N. As described above, each of the arms of the multiple phases is similarly switched, so that the current flows in the same manner between the arm and the neutral point 7N in each of the coils 7 of the multiple phases. Therefore, the coils 7 of the multiple phases can be regarded as one coil, and the coil 7 functions as a choke coil in the chopper circuit, with one end connected to the midpoint of the switching circuit (the connection point between the upper-stage switching element 5U and the lower-stage switching element 5L connected in series), and the other end connected to the output capacitor Cs. The output capacitor Cs connected between the neutral point 7N and the ground can be said to be connected between the choke coil and the ground.

[0033] As shown in Fig. 2, the on-board charging device 10 includes a main contactor 11, an OBC contactor 12, and a grid contactor 13. These contactors are configured with relays or the like, and are controlled by a control device 80, or by both the control device 80 and a vehicle control device 90. As described above with reference to Fig. 1, the control device 80 is included in the drive control system of the rotating electric machine, and it can be said that the control device 80 is also used in common for drive control of the rotating electric machine 70 and charge control of the DC power source 3.

[0034] As described above with reference to FIG. 1, the main contactor 11 is installed so as to be able to electrically connect and disconnect the DC power source 3 and the inverter 5. When the inverter 5 and the coil 7 of the rotating electric machine 70 are also used as the in-vehicle charging device 10, the connection form with the DC power source 3 is switched. For this reason, the main contactor 11 has a main contactor first contact 11a and a main contactor second contact 11b. When the inverter 5 functions as the vehicle drive device 9, the main contactor first contact 11a is closed and the main contactor second contact 11b is opened. When the inverter 5 functions as the in-vehicle charging device 10, the main contactor second contact 11b is closed and the main contactor first contact 11a is opened. When the DC power source 3 is not charged and the vehicle is parked, the main contactor 11 can be opened by opening both the main contactor first contact 11a and the main contactor second contact 11b.

[0035] In the closed state, the OBC contactor 12 electrically connects the output of the second circuit 2 serving as a DC-DC converter to the DC power source 3. Specifically, in the closed state, the OBC contactor 12 connects the neutral point 7N to the positive electrode of the DC power source 3, and also connects the positive terminal of the output capacitor Cs to the positive electrode of the DC power source 3. As described above, the grid contactor 13 electrically connects and disconnects the first circuit 1 to the external AC power source 4.

[0036] 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 OBC contactor 12 and the grid contactor 13 are controlled to be in an open state, and power is converted between the DC power source 3 and the rotating electric machine 70 via the inverter 5. When the inverter 5 is used as the in-vehicle charging device 10, the main contactor second contact 11b is closed, and the OBC contactor 12 and the grid contactor 13 are controlled to be in a closed state, and the DC power source 3 is charged by the external AC power source 4.

[0037] In this way, it is possible to realize a circuit that can switch between a function of driving and controlling the rotating electric machine 70 and a function of charging the DC power supply 3 with the external AC power supply 4, simply by changing the connection form of the inverter 5 and the coil 7. That is, it is possible to configure the in-vehicle charging device 10 with a simple configuration.

[0038] In recent years, it has been proposed to use the DC power source 3 of an electric vehicle or a hybrid vehicle as an emergency power source in the event of a disaster or the like. The second circuit 2 is a bidirectional chopper circuit, and functions as a step-down converter from the first circuit 1 (AC-DC converter) to the DC power source 3, and functions as a step-up converter from the DC power source 3 to the first circuit 1 (in this case, the DC-AC converter). As shown in FIG. 2, the first circuit 1 includes a full bridge circuit, so that the first circuit 1 can function not only as an AC-to-DC converter but also as a bidirectional power converter having a DC-to-AC converter function. That is, the first circuit 1 performs DC-to-AC conversion, and commercial AC power can be output from the first circuit 1, and the DC power source 3 can be used as an emergency power source.

[0039] Naturally, when the use of such a DC power source 3 is not taken into consideration, the first circuit 1 may be configured as a unidirectional converter that performs only AC-DC conversion, and therefore may be configured with, for example, a half-bridge circuit without having a full-bridge circuit.

[0040] When the in-vehicle charging device 10 charges the DC power supply 3 from the external AC power supply 4, the first circuit 1 functions as a dual active bridge AC / DC DAB Boost Converter, and the second circuit 2 functions as a DC / DC Buck Converter. When the in-vehicle charging device 10 functions as an emergency AC power supply that outputs AC power using power stored in the DC power supply 3, the second circuit 2 functions as a DC / DC Boost Converter, and the first circuit 1 functions as a dual active bridge DC / AC DAB Buck Converter.

[0041] The circuit block diagram of FIG. 7 shows a comparative example (comparative example charging device 10X) for the in-vehicle charging device 10 according to the present embodiment. The comparative example charging device 10X includes an AC-DC converter 100 that converts power between AC power on the side of the external AC power source 4 and a first DC power, and a DC-DC converter 200 that generates a second DC power from the first DC power to charge the DC power source 3. Unlike the in-vehicle charging device 10 according to the present embodiment, the comparative example charging device 10X uses the drive circuit of the rotating electric machine 70 in the AC-DC converter 100. Specifically, the AC-DC converter 100 includes an inverter 5, a multi-phase coil 7, a single-phase arm 105 connected in parallel to the inverter 5, and a first inductor L1. The first inductor L1 and the external AC power source 4 are connected in series between the neutral point 7N of the multi-phase coil 7 and the midpoint of the single-phase arm 105. The three-phase arms constituting the inverter 5 are connected in parallel to seemingly constitute one arm, and together with the single-phase arm 105, form a full bridge (H bridge).

[0042] Generally, a rotating electric machine that is a driving force source of a vehicle is designed to have a high power density and has a small inductance. Therefore, when the coil 7 is used in the AC-DC converter 100 as in the comparative 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 due to insufficient inductance. In order to compensate for the insufficient inductance, in the comparative charging device 10X, not only the coil 7 but also a first inductor L1 is added as an input inductor of the AC-DC converter 100.

[0043] The DC-DC converter 200 is a chopper circuit including a switching circuit in which switching elements are connected in series so as to be switched complementarily, a second inductor L2 serving as a choke coil, and an output capacitor Cs connected to the second inductor L2.

[0044] The comparative charging device 10X also includes a main contactor 11, a grid contactor 13, and an OBC contactor 12. The OBC contactor 12 of the comparative charging device 10X includes two contacts, an OBC contactor first contact 12a and an OBC contactor second contact 12b, and selectively connects the AC-DC converter 100 (inverter 5) to the DC power source 3, or connects the AC-DC converter 100 (inverter 5) to the DC-DC converter 200. When the inverter 5 functions as the 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 control the drive of the rotating motor 70, the OBC contactor first contact 12a is closed and the OBC contactor second contact 12b is opened, and the positive side of the inverter 5 is connected to the DC power source 3 via the OBC contactor 12 and the main contactor 11.

[0045] In the embodiment illustrated in FIG. 7, the first inductor L1 is added to compensate for the inductance of the coil 7 of the rotating electric machine 70 that serves as the driving force source of the vehicle. However, it is also possible to increase the control frequency of the inverter 5 included in the AC-DC converter 100 and the switching circuit of the DC-DC converter 200 without adding the first inductor L1. However, when the control frequency is increased, the control period (control frequency) of the control device 80 must also be shortened. Switching at a high frequency increases the loss in the switching elements included in the AC-DC converter 100 (inverter 5) and the DC-DC converter 200, leading to a decrease in the efficiency of the 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 80, which leads to an increase in the cost of the comparative charging device 10X. In view of this, if the first inductor L1 that compensates for the insufficient inductance is arranged as illustrated in FIG. 7, it is likely to lead to an increase in the system cost.

[0046] In the vehicle-mounted charging device 10 of this embodiment, the coil 7 of the rotating electric machine 70 and the inverter 5 are used in the second circuit 2 functioning as a DC-DC converter, not in the first circuit 1 functioning as an AC-DC converter. In the second circuit 2, the coil 7 functions as a reactor, but does not require a larger inductance than the input inductor Li (boost inductor) in the AC-DC converter. Therefore, unlike the comparative charging device 10X, it is possible to configure a DC-DC converter with the coil 7 as a reactor without providing an additional inductor in series with the coil 7. In addition, since the input inductor Li having an appropriate inductance for configuring the AC-DC converter can be arranged in the first circuit 1, it is not necessary to increase the control frequency when controlling the switching of the first circuit 1 and the second circuit 2. Therefore, the control device 80 is not required to use a microcomputer or the like capable of high-speed operation. In this way, the vehicle-mounted charging device 10 of this embodiment can suppress an increase in system cost compared to the comparative charging device 10X.

[0047] Although not shown, in a configuration in which the coil 7 of the rotating electric machine 70 and the inverter 5 are used in the second circuit 2, the first circuit 1 can be a switching rectifier circuit like the comparative charging device 10X, instead of a dual active bridge circuit using a transformer T as in this embodiment. However, in this case, since the external AC power supply 4 and the DC power supply 3 are not electrically independent from each other, a relatively high leakage current may flow to the common ground. Since there is a possibility that a user is present near the vehicle while the DC power supply 3 is being charged, it is preferable that measures are taken against such leakage current. In addition, in a configuration in which the external AC power supply 4 and the DC power supply 3 are not electrically independent from each other, when a short circuit or the like occurs in the external AC power supply 4, a large short circuit current may flow to the DC power supply 3 of the vehicle or to an in-vehicle device connected to the DC power supply 3.

[0048] In the in-vehicle charging device 10 of this embodiment, the first circuit 1 is configured as a dual active bridge circuit using a transformer T, and thus the external AC power source 4 is insulated from the DC power source 3 and the in-vehicle device connected to the DC power source 3. This makes it easier to ensure the safety of the user while the DC power source 3 is being charged, and also makes it possible to suppress the impact on the vehicle of a short-circuit failure of the external AC power source 4 while the DC power source 3 is being charged.

[0049] The circuit block diagram of FIG. 3 shows a second example of the in-vehicle charging device 10 using the drive control system of the rotating electric machine 70. The second example is different from the first example shown in FIG. 2 in the configuration of the primary side bridge circuit 111 of the primary side circuit 1a of the first circuit 1, but the other configurations are the same. In the first example, the primary side bridge circuit 111 is configured to include a full bridge circuit using a bidirectional switching element as the switching element 11S. In the second example, the primary side bridge circuit is configured to include a center tap type half bridge circuit using a bidirectional switching element.

[0050] In this configuration, an external AC power supply 4 is connected between the midpoint of the half-bridge circuit (the connection point of the switching elements 11S connected in series) and the midpoint of the primary coil T1. Filter inductors Lf are disposed between the upper-stage switching element 11S and the primary coil T1, and between the lower-stage switching element 11S and the secondary coil T2. Filter capacitors Cf are disposed on the side of the upper-stage switching element 11S and the side of the lower-stage switching element 11S.

[0051] The circuit block diagram in Fig. 4 shows a third example of the on-board charging device 10 using a drive control system for a rotating electric machine 70. In the first and second examples, the external AC power supply 4 is a single-phase AC power supply, whereas in the third example, the external AC power supply 4 is a multi-phase AC power supply. Here, the external AC power supply 4 is connected at a neutral point 4N and is configured with three AC power supplies with phase differences of 2π / 3. Corresponding to the three AC power supplies, the grid contactor 13 is also configured with three contacts.

[0052] The primary circuit 1a of the first circuit 1 is configured as a three-phase AC-DC converter to convert power from three-phase AC to DC. The primary bridge circuit 111 is configured to have three arms corresponding to each of the three phases, similar to the inverter 5. Note that, in the third example, the primary bridge circuit 111 is also configured using bidirectional switching elements. A filter inductor Lf and a filter capacitor Cf are connected to the connection point of the switching element 11S in the arm of each phase.

[0053] Incidentally, rotating electric machines mounted on a vehicle are not limited to traction motors that drive the wheels, but also include motors that drive compressors of on-board air conditioners and motors that drive electric oil pumps. Note that, since the focus here is on "drive," the term "motor" is used, but here, "motor" and "rotating electric machine" are synonymous. Since the on-board air conditioner and the electric oil pump are called accessories in comparison with the vehicle drive device 9 as the main engine, in the following description, the motor that serves as the driving force source for the wheels will be called the traction motor, and the motor that serves as the driving force source for the on-board air conditioner and the electric oil pump will be called the accessory motor that serves as the driving force source for the accessories.

[0054] In a conventional automobile, that is, a vehicle equipped with a battery having an output voltage of about 12 volts to about 24 volts and using an internal combustion engine as a driving force source for the wheels, the auxiliary motor is also driven by power supplied from the 12 volt battery. In an electric automobile using a traction motor as a driving force source for the wheels and a hybrid automobile using an internal combustion engine and a traction motor as a driving force source for the wheels, a high-voltage DC power supply having an output voltage of about 48 volts to about 400 volts is installed to supply power to the traction motor. Even in an electric automobile or a hybrid automobile, a low-voltage battery having an output voltage of about 12 volts to about 48 volts may be installed, and power for driving the auxiliary motor may be supplied from the battery. In addition, such a low-voltage battery may be supplied with power stepped down from a high-voltage DC power supply (corresponding to the DC power supply 3 in this embodiment) via a DC-DC converter.

[0055] However, loss occurs when the voltage is stepped down from the high-voltage DC power supply through a DC-DC converter. In addition, the auxiliary motor can easily output a high output and can be more efficient when driven at a high voltage. For this reason, in recent years, the auxiliary motor may also be driven by high-voltage power supplied from the high-voltage DC power supply (DC power supply 3). In such a case, it is also preferable to use an auxiliary motor, rather than a driving motor, in a circuit that also serves as a reactor or a switching circuit in the second circuit 2 of the in-vehicle charging device 10. In this embodiment, various forms of the "in-vehicle charging device using a drive control system for a rotating electric machine" are exemplified, but the "rotating electric machine" used in the "in-vehicle charging device 10" is not limited to the driving motor (rotating electric machine 70) and also includes the auxiliary motor 8M.

[0056] Hereinafter, an example will be given of an "on-vehicle charging device utilizing a drive control system for an accessory motor (an accessory rotating electric machine)." The drive system for the accessory motor can be easily understood by those skilled in the art by replacing the travel motor (rotating electric machine 70) with the accessory motor 8M (an accessory rotating electric machine), the coil (coil 7) of the travel motor with the accessory motor coil 8, the neutral point 7N of the coil 7 with the neutral point 8N of the accessory motor coil 8, the inverter 5 with the accessory inverter 50, and the switching element 5S with the switching element 50S in the drive system of the vehicle drive device 9 shown in Fig. 1, and therefore illustrations and detailed explanations will be omitted.

[0057] The circuit block diagram of FIG. 5 shows an on-vehicle charging device 10 using a drive control system for an auxiliary motor 8M as a fourth example of the on-vehicle charging device 10 using a drive control system for a rotating electric machine. The circuit block diagram of FIG. 5 is obtained by adding a drive control system for the auxiliary motor 8M to the circuit block diagram of FIG. 1. However, unlike FIG. 1, nothing is connected to the neutral point 7N of the coil 7 of the rotating electric machine 70, which is a travel motor, even if selectively, and neither the coil 7 nor the inverter 5 is used in the on-vehicle charging device 10. The second circuit 2 is configured using the auxiliary motor 8M and a drive circuit for the auxiliary motor 8M.

[0058] That is, the second circuit 2 is a chopper circuit including a switching circuit configured using the auxiliary inverter 50, a choke coil configured using a multi-phase auxiliary motor coil 8, and an output capacitor Cs connected to a neutral point 8N of the multi-phase auxiliary motor coil 8. As shown in FIG. 5, the auxiliary inverter 50 is also configured with a number of arms (here, three corresponding to three phases) corresponding to the number of phases of the AC, each of which has an upper-stage switching element 50U and a lower-stage switching element 50L connected in series, in parallel. When the auxiliary inverter 50 functions as a switching circuit of the chopper circuit, all of the upper-stage switching elements 50U of the multiple arms are simultaneously and similarly controlled to be turned on and off, and all of the lower-stage switching elements 50L of the multiple arms are simultaneously and similarly controlled to be turned on and off. Therefore, the auxiliary inverter 50 having multiple arms apparently functions as a switching circuit configured by one arm in which the upper-stage switching element 50U and the lower-stage switching element 50L are connected in series.

[0059] One end of each of the auxiliary motor coils 8 of the multiple phases is connected to the midpoint of the corresponding arm (the connection point between the upper-stage switching element 50U and the lower-stage switching element 50L), and the other end is connected to the neutral point 8N of the auxiliary motor coil 8. As described above, each of the multiple phase arms is switched and controlled in the same way, so that the same current flows in each auxiliary motor coil 8 between the arm and the neutral point 8N. Therefore, the auxiliary motor coils 8 of the multiple phases can be regarded as one coil. The connection relationship between the OBC contactor 12 and the output capacitor Cs is the same as that shown in Figs. 2 to 4, so a detailed description thereof will be omitted.

[0060] The circuit block diagram of FIG. 6 shows an on-vehicle charging device 10 using a drive control system for an auxiliary motor 8M as a fifth example of the on-vehicle charging device 10 using a drive control system for a rotating electric machine. The difference between the fourth example shown in FIG. 5 and the fifth example shown in FIG. 6 is the difference between the first example shown in FIG. 2 and the second example shown in FIG. 3 in that the configuration of the primary side bridge circuit 111 of the primary side circuit 1a of the first circuit 1 is different, and the other configurations are the same. That is, in the fourth example, the primary side bridge circuit 111 is configured to include a full bridge circuit, whereas in the fifth example, the primary side bridge circuit is configured to include a center tap type half bridge circuit. In particular, there is no difference between the fourth example and the fifth example in the second circuit 2, so a detailed description thereof will be omitted.

[0061] Although illustrations and detailed explanations are omitted, similar to the third example illustrated in FIG. 4, in the in-vehicle charging device 10 utilizing the drive control system for the auxiliary motor 8M, the external AC power source 4 may be a three-phase AC.

[0062] As in the fourth and fifth examples, when a vehicle is equipped with a first rotating electric machine and a second rotating electric machine both connected to a DC power source 3, i.e., when the vehicle is equipped with a first rotating electric machine (travel motor, rotating electric machine 70) that serves as a power source for the wheels, and a second rotating electric machine (accessory motor 8M) that serves as a driving power source for the accessories mounted on the vehicle, a rotating electric machine in which a coil and an inverter are used in the vehicle-mounted charging device 10 can be the second rotating electric machine.

[0063] Auxiliary rotating electric machines, which require smaller torque than those for driving wheels, often have smaller coils and inverters for driving the rotating electric machines. When a first rotating electric machine (travel motor, rotating electric machine 70) having a relatively large circuit and a second rotating electric machine (accessory motor 8M) having a relatively small circuit are both connected to a DC power source 3, the circuit of the second rotating electric machine is often sufficient for charging. By configuring the on-board charging device 10 using the circuit of the second rotating electric machine instead of the circuit of the first rotating electric machine, which is used for driving wheels and is easily consumed, the burden on the vehicle on which the on-board charging device 10 is mounted can also be reduced.

[0064] Naturally, even if the vehicle has a first rotating electric machine and a second rotating electric machine both connected to a DC power source 3, as in the first, second and third examples, the rotating electric machine in which a coil and an inverter are used in the vehicle-mounted charging device 10 may be the traction motor (rotating electric machine 70) that is the driving force source for the wheels.

[0065] When a vehicle is equipped with a rotating electric machine 70 that serves as a driving force source for the wheels, the DC power source 3 that provides driving power to the rotating electric machine 70 can be charged using the coil 7 of the rotating electric machine 70 and the inverter 5 that drives the rotating electric machine 70, thereby enabling an efficient configuration of an on-board charging device 10 by sharing circuits. [Explanation of symbols]

[0066] 1: first circuit, 2: second circuit, 3: DC power supply, 4: external AC power supply, 5: inverter, 5S: switching element, 7: coil, 7N: neutral point, 8M: auxiliary motor (second rotating electric machine), 8N: neutral point, 10: on-board charging device, 70: rotating electric machine (rotating electric machine, first rotating electric machine), 111: primary side bridge circuit, 112: secondary side bridge circuit, Cs: output capacitor, T: transformer, T1: primary side coil, T2: secondary side coil

Claims

1. An on-board charging device is mounted on a vehicle including a rotating electric machine having coils of multiple phases connected to each other at a neutral point, an inverter that converts power between direct current and multiple phase alternating current, and a direct current power source that is connected to the rotating electric machine via the inverter, and charges the direct current power source with power supplied from an external alternating current power source, a first circuit that converts power between AC power on the side of the external AC power supply and a first DC power; a second circuit that generates a second DC power from the first DC power to charge the DC power supply; The second circuit is A switching circuit configured using the inverter; A choke coil configured using the coils of multiple phases; an output capacitor connected to the neutral point of the coils of the multiple phases; A chopper circuit comprising: The first circuit is a transformer having a primary coil and a secondary coil; A primary bridge circuit connected to the primary coil; a secondary bridge circuit connected to the secondary coil; A dual active bridge circuit comprising: The primary bridge circuit is configured with a bidirectional switching element.

2. The in-vehicle charging device according to claim 1 , wherein the primary side bridge circuit is a full bridge circuit.

3. The vehicle-mounted charging device according to claim 1 or 2, wherein the rotating electric machine is a driving power source for wheels.

4. the vehicle includes a first rotating electric machine that serves as a driving power source for wheels, and a second rotating electric machine that serves as a driving power source for accessories mounted on the vehicle, the first rotating electric machine and the second rotating electric machine are both connected to the DC power supply, The vehicle-mounted charging device according to claim 1 , wherein the rotating electric machine is the second rotating electric machine.

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