Onboard charger

Abstract

To configure an onboard charger so as to suppress increase in a system cost by using a coil of an onboard rotary electric machine and an inverter, the onboard charger charging an onboard DC power supply with power from an external AC power supply.SOLUTION: An onboard charger includes: an AC-DC converter 1 that converts power between AC power on a side of an external AC power supply 4 and first DC power; and a DC-DC converter 2 that converts power between the first DC power and second DC power on a side of a DC power supply 3. The DC-DC converter 2 includes an H bridge circuit including a first arm 21 on the side of the AC-DC converter 1, a second arm on the side of the DC power supply 3, and a reactor disposed between the first arm 21 and the second arm. The reactor is configured using a plurality of coils 7 of a rotary electric machine, and the second arm is configured using an inverter 5.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 that is a driving force source for the wheels of the vehicle can be used as the three-phase coil. FIG. 12 shows an example of a charging device 10X that is a conventional example of such an on-board charging device. The charging device 10X is configured to share the coil 7 of the rotating electric machine 70 that is a driving force source for the wheels and the inverter 5 that drives and controls the rotating electric machine 70. The charging device 10X is configured to have a first converter 100 that is an AC-DC converter and a second converter 200 that is a DC-DC converter. The first converter 100 is configured using the coil 7 and the inverter 5, and an external AC power source 4 is connected to the neutral point 7N of the multiple-phase coils 7 of the rotating electric machine 70. The first converter 100 and the second converter 200 are selectively connected via a function switching contactor 12. When the coil 7 and the inverter 5 are used to drive the wheels, the first function switching contactor contact 12a is closed, and when the coil 7 and the inverter 5 are used to charge the DC power source 3, the second function switching contactor contact 12b is closed.

[0005] However, the rotating electric machine that serves as the driving force source for the wheels is designed to have a high power density, and the coil 7 has a small inductance as an inductor of the AC-DC converter. Therefore, during AC-DC conversion, the peak value of the pulsation of the harmonic current of the system current of the external AC power source 4 tends to become large. As one method for suppressing this, it is considered to increase the control frequency of the inverter 5 constituting the first converter 100. Alternatively, it is considered to increase the control frequency of the DC-DC converter in order to reduce the pulsation on the side of the second converter 200. However, when the control frequency is increased, it is necessary to shorten the control period (operation frequency) of the control device that controls the inverter 5 and the DC-DC converter. In addition, switching at a high frequency associated with a fast control period increases the loss in the switching elements provided in the inverter 5 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. As another method, it is possible to add an inductor (L1) between the external AC power supply 4 and the neutral point 7N of the coil 7 as shown in Fig. 12. However, even in this case, the addition of the inductor (L1) leads to an increase in the cost of the on-board charging device.

[0006] In view of the above background, it is desirable to configure an on-board charging device that uses a 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 suppressing increases in system costs. [Means for solving the problem]

[0007] In view of the above, an on-board charging device is provided which is mounted on a vehicle including a rotating electric machine having multiple phase coils connected to each other at a neutral point and serving as a driving force source for wheels, an inverter which converts power between DC and multiple phase AC, and a DC power source which is connected to the rotating electric machine via the inverter, and which charges the DC power source with power supplied from an external AC power source, and which includes an AC-DC converter which converts power between AC power on the external AC power source side and a first DC power, and a DC-DC converter which converts power between the first DC power and a second DC power on the DC power source side, and the DC-DC converter includes an H-bridge circuit including a first arm on the AC-DC converter side, a second arm on the DC power source side, and a reactor arranged between the first arm and the second arm, and the reactor is configured using a plurality of the coils, and the second arm is configured using the inverter.

[0008] According to this configuration, the AC / DC converter, which requires an appropriate inductance, is configured without using the drive circuit (coil and inverter) of the rotating electric machine, among the AC / DC converter and the DC / DC converter that configure the on-board charging device. When the coil of the rotating electric machine is used in the on-board charging device, it may be difficult to ensure the required performance due to the small inductance of the coil. However, according to this configuration, the AC / DC converter can be configured while ensuring sufficient performance such as power factor correction by using the AC / DC converter that can set an appropriate inductance without using the coil of the rotating electric machine. In addition, since the DC / DC converter is configured using the drive circuit of the rotating electric machine, the cost of the on-board charging device can be reduced. Furthermore, since an appropriate inductance can be set in the AC / DC converter, it is not necessary to control the AC / DC converter with a short control period (high control frequency), and the loss of the switching element that configures the AC / DC converter can be easily reduced.

[0009] In addition, the coils of the multiple phases connected in parallel to each other at the neutral point appear as one coil, and can form a reactor. In addition, the arms of each phase of the inverter connected in parallel appear as one phase arm (half bridge), and can form a second arm. By disposing a coil between the first arm and the second arm, an H-bridge circuit can be formed by the first arm, the reactor (coil), and the second arm (inverter). A DC-DC converter equipped with an H-bridge circuit is capable of both stepping down and stepping up the voltage. Some DC power supplies mounted on vehicles to supply power to a rotating electric machine that drives the wheels have different rated voltages. Even for the same vehicle model, the rated voltage of the DC power supply may differ depending on the grade. For example, a higher grade may be equipped with a DC power supply with a higher rated voltage to obtain a higher output. If this voltage is higher than the voltage obtained by performing AC-DC conversion from a general commercial power supply, a step-up is required in the DC-DC converter. If on-board charging devices with different configurations are mounted depending on the vehicle, economies of scale cannot be obtained, and the reduction in the cost of the on-board charging device is limited. However, by configuring the DC-DC converter with a step-up / step-down function, the same hardware can be used and the control form (e.g., software such as a program) can be changed to deploy the same on-board charging device in a variety of grades and vehicle models.

[0010] Thus, with this configuration, 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 can be constructed while suppressing increases in system costs.

[0011] 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]

[0012] [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] FIG. 1 is a diagram illustrating a current flow when a DC-DC converter that functions as a step-down converter when charging a DC power source charges an output capacitor; [Figure 4] FIG. 1 illustrates the flow of current returning through a DC-DC converter functioning as a step-down converter when charging a DC power source. [Diagram 5] FIG. 1 illustrates the flow of current returning through a DC-DC converter functioning as a boost converter when charging a DC power source. [Figure 6] FIG. 1 is a diagram illustrating an example of a current flow when a DC-DC converter that functions as a boost converter when charging a DC power source charges a reactor. [Figure 7] 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 8] A circuit block diagram showing a third example of an on-board charging device using a drive control system for a rotating electric machine. [Figure 9] 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 10] 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 11] A circuit block diagram showing a sixth example of an on-board charging device using a drive control system for a rotating electric machine. [Figure 12] A circuit block diagram showing a conventional example of an on-board charging device using a drive control system for a rotating electric machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 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.

[0014] 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. The vehicle-mounted charging device 10 is configured to share some parts with the vehicle drive device 9. Specifically, the inverter 5 and the coil 7 of the rotating electric machine 70 are shared. In the embodiment shown in FIG. 2, the external AC power source 4 is connected to an AC-DC converter 1 described later via an EMI filter FLT. The EMI filter FLT can be disposed as appropriate, and the EMI filter FLT may be provided even when it is not illustrated in the examples other than the first example. Conversely, even when the EMI filter FLT is illustrated, the vehicle-mounted charging device 10 may be configured without the EMI filter FLT.

[0015] 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.

[0016] As shown in FIG. 1, the vehicle drive device 9 includes an inverter 5. The inverter 5 is connected to an AC rotating electric machine 70 and a DC power source 3, and converts power between multiple phase AC and DC. A pair of DC side terminals 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 (which may be called legs). 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, i.e., the connection point between the upper stage switching element 5U and the lower stage switching element 5L, is connected to the respective coils 7. Specifically, the midpoint of the U-phase arm is connected to U-phase coil 7u, the midpoint of the V-phase arm is connected to V-phase coil 7v, and the midpoint of the W-phase arm is connected to W-phase coil 7w.

[0017] The DC side of the inverter 5 is provided with a smoothing capacitor (DC link capacitor 6) that smoothes the voltage (DC link voltage) between the positive and negative poles. The DC side of the inverter 5 is also provided with a voltage sensor (DC link voltage sensor 61) that detects the DC link voltage. The DC link capacitor 6 is referred to as a "first DC link capacitor" when distinguished from a capacitor (second DC link capacitor Cd) that smoothes the DC link voltage (first DC voltage) of the in-vehicle charging device 10 described later.

[0018] The DC power source 3 is, for example, a rechargeable secondary battery (battery) such as a lithium ion battery, an electric double layer capacitor, or the like. When the rotating electric machine 70 is the driving force source of the vehicle as in this embodiment, the DC power source 3 is a high-voltage, large-capacity DC power source, and the rated power supply voltage is, for example, 200 to 800 [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.

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

[0020] As shown in FIG. 1, the inverter 5 is configured to have a plurality of switching elements 5S. In this embodiment, a form in which a FET (Field Effect Transistor) is used as the switching element 5S is illustrated. In addition to the FET, an IGBT (Insulated Gate Bipolar Transistor) may be used as the switching element 5S. In this embodiment, a freewheel diode is connected in parallel to each switching element 5S with the forward direction being the direction from the negative electrode to the positive electrode (the direction from the lower stage to the upper stage). Of course, in the case of using a body diode or in the case of using reverse conduction in a transistor of a wide band gap semiconductor made of enhancement mode gallium nitride (E-Gan), such a form of freewheel diode may not be provided.

[0021] 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 component. For example, the control device 80 performs current feedback control 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. The operating voltage of a logic circuit element such as a microcomputer is generally 5 volts or less. In this embodiment, although not shown for simplification, a control signal generated by the logic circuit element is transmitted to the inverter 5 via a drive circuit. Alternatively, the control device 80 may be considered to include a drive circuit.

[0022] The actual current flowing through the coils 7 of each phase of the rotating electric machine 70 is detected by a current sensor (motor current sensor 81), and the control device 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 (program).

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

[0024] 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, which is determined by the phase of the AC voltage and current, is close to "1". For this reason, the AC-DC converter often includes a power factor correction circuit using a switching element so that the power factor can be improved.

[0025] 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.

[0026] The vehicle-mounted charging device 10 of this embodiment charges the DC power source 3 of the vehicle drive device 9 with power supplied from an external AC power source 4. That is, the vehicle-mounted charging device 10 of this embodiment is mounted on a vehicle equipped with a rotating electric machine 70 that is a driving force source for the wheels, an inverter 5 that converts power between DC and multiple-phase AC, and a DC power source 3 connected to the rotating electric machine 70 via the inverter 5, and charges the DC power source 3 with power supplied from the external AC power source 4. Various forms will be described below by way of examples. The circuit block diagram of FIG. 2 shows a first example of the vehicle-mounted charging device 10, which is the most basic configuration.

[0027] 2, the in-vehicle charging device 10 includes an AC-DC converter 1 that converts power between AC power on the side of an external AC power source 4 and a first DC power, and a DC-DC converter 2 that converts power between the first DC power and a second DC power on the side of a DC power source 3. As described later, in this embodiment, the AC-DC converter 1 connected to the external AC power source 4 is configured by a circuit formed separately from a vehicle drive device 9, and the DC-DC converter 2 connected to the DC power source 3 is configured to share a drive system circuit (coils 7 and inverter 5) of a rotating electric machine 70.

[0028] As shown in Fig. 2, the AC-DC converter 1 is configured to include a switching element 1S. In AC-DC conversion, a phase difference occurs between the voltage phase and the current phase due to inductive impedance and capacitive impedance, and the power factor decreases due to the phase difference. By controlling the switching element 1S, for example, the current phase is adjusted, the phase difference is compensated for, and the power factor can be improved. The AC-DC converter 1 is also configured to function as a power factor correction (PFC) circuit that improves the power factor of DC power converted from AC power supplied from an external AC power source 4.

[0029] The AC-DC converter 1 is also configured to include an input inductor Li and a full-bridge circuit using a switching element 1S. That is, the power factor correction circuit is configured as a totem-pole type power factor correction circuit. By including such a full-bridge circuit in the AC-DC converter 1, the AC-DC converter 1 functions as a bidirectional power converter capable of converting AC to DC and DC to AC.

[0030] The DC-DC converter 2 includes an H-bridge circuit including a first arm 21 on the side of the AC-DC converter 1, a second arm (inverter 5) on the side of the DC power source 3, and a reactor (coil 7) disposed between the first arm 21 and the second arm. As described above, the DC-DC converter 2 is configured to share the drive circuit (coil 7 and inverter 5) of the rotating electric machine 70. The first arm 21 is configured as a half-bridge circuit made up of a switching element 2S. The reactor is configured using a plurality of coils 7, and the second arm is configured using the inverter 5.

[0031] Specifically, the coils 7 of the multiple phases connected in parallel appear as one coil, forming a reactor. The arms of the phases connected in parallel appear as one phase arm (half bridge), forming a second arm. The neutral point 7N of the coil 7 is connected to the midpoint of the first arm 21 (the connection point of the upper-stage switching element 2U and the lower-stage switching element 2L of the first arm). The end of the coil 7 of each phase opposite to the neutral point 7N is connected to the midpoint of the arm of each phase of the inverter 5 (the connection point of the upper-stage switching element 5U and the lower-stage switching element 5L of each arm). Therefore, the first arm 21, the reactor (coil 7), and the second arm (inverter 5) form an H-bridge circuit. The reactor may be called a choke coil.

[0032] The DC-DC converter 2 equipped with an H-bridge circuit is capable of both stepping down and stepping up. The DC power source 3 mounted on the vehicle to supply power to the rotating electric machine 70 that drives the wheels may have different rated voltages. Even for the same vehicle model, the rated voltage of the DC power source 3 may differ depending on the grade. For example, in a higher grade, a DC power source 3 with a higher rated voltage may be mounted in order to obtain a higher output. If this voltage is higher than the voltage obtained by performing AC-DC conversion on the external AC power source 4, which is a general commercial power source, the DC-DC converter 2 needs to step up the voltage. If an in-vehicle charging device 10 with a different configuration is mounted on each vehicle, economies of scale cannot be obtained, and the reduction in the cost of the in-vehicle charging device 10 is limited. However, since the DC-DC converter 2 is configured to have a step-up and step-down function, the same hardware can be used and the same in-vehicle charging device 10 can be deployed in various grades and various vehicle models by changing the control form (for example, software such as a program).

[0033] In the in-vehicle charging device 10 of this embodiment, the AC-DC converter 1 is an AC-DC boost converter, and the DC-DC converter 2 is configured to function as a DC-DC boost converter or a DC-DC step-down converter depending on the rated voltage of the DC power source 3. That is, the full bridge circuit of the AC-DC converter 1 functions as an AC-DC step-up converter. The H-bridge circuit of the DC-DC converter 2 functions as a DC-DC step-up converter or a DC-DC step-down converter depending on the rated voltage of the DC power source 3. Specifically, when the rated voltage of the DC power source 3 is higher than the voltage of the first DC power (first DC voltage), the DC-DC converter 2 (H-bridge circuit) functions as a step-up converter. On the other hand, when the rated voltage of the DC power source 3 is lower than the voltage of the first DC power (first DC voltage), the DC-DC converter 2 (H-bridge circuit) functions as a step-down converter.

[0034] The switching between the step-up and step-down functions of the DC-DC converter 2 is realized by control, as described later with reference to Figs. 3 to 6. That is, the same hardware is used and the function is switched by software. Since the rated voltage of the DC power source 3 is known in the vehicle in which the vehicle-mounted charging device 10 is mounted, the vehicle-mounted charging device 10 is appropriately charged by the power supplied from the external AC power source 4 according to the rated voltage of the DC power source 3 by control based on a preset program (software). That is, the vehicle-mounted charging device 10 of this embodiment can charge the DC power source 3 using the same hardware according to the rated voltage of the DC power source 3, regardless of whether the rated voltage of the DC power source 3 is higher or lower than the voltage of the first DC power (first DC voltage).

[0035] As described above, the AC-DC converter 1 converts power between the AC power and the first DC power. The DC-DC converter 2 converts power between the first DC power and the second DC power. Therefore, the voltage between the AC-DC converter 1 and the DC-DC converter 2 is the first DC voltage, which is the voltage of the first DC power, and is the DC link voltage in the in-vehicle charging device 10. A second DC link capacitor Cd is disposed between the AC-DC converter 1 and the DC-DC converter 2 to smooth the first DC voltage (the DC link voltage of the in-vehicle charging device 10).

[0036] Moreover, the voltage between the second arm (inverter 5) and the DC power source 3 is a second DC voltage which is the voltage of the second DC power, and is a voltage for charging the DC power source 3. In other words, it is a voltage between the positive and negative poles of the DC power source 3, and can be called a battery voltage. From the viewpoint of charging the DC power source 3, the second DC voltage can also be called an output voltage of the in-vehicle charging device 10. An output capacitor Cs is disposed between the second arm (inverter 5) and the DC power source 3. The output capacitor Cs also serves as the DC link capacitor 6 (first DC link capacitor) described with reference to FIG. 1.

[0037] Like the AC-DC converter 1, the DC-DC converter 2 has both a function of generating a second DC power from a first DC power (a function of converting a first DC voltage to a second DC voltage) and a function of generating a first DC power from a second DC power (a function of converting a second DC voltage to a first DC voltage). Since both the AC-DC converter 1 and the DC-DC converter 2 have a function of converting power in both directions, the vehicle-mounted charging device 10 is a bidirectional power conversion device having a function of converting power in both directions between AC power and the second DC power (battery power). 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 vehicle-mounted charging device 10 of this embodiment not only charges the DC power source 3, but also has a function of being able to use the DC power source 3 as an AC emergency power source.

[0038] When the vehicle-mounted charging device 10 charges the DC power supply 3 from the external AC power supply 4, the AC-DC converter 1 functions as a unity power factor AC-DC boost converter (AC / DC Boost Converter UPF (Unity Power Factor)), and the DC-DC converter 2 functions as a DC / DC Buck Boost Converter. When the vehicle-mounted charging device 10 functions as an emergency AC power supply that outputs AC power using power stored in the DC power supply 3, the DC-DC converter 2 functions as a DC / DC Buck Boost Converter, and the AC-DC converter 1 functions as a unity power factor DC-AC Buck Converter UPF.

[0039] As shown in Fig. 2, the in-vehicle charging device 10 includes a main contactor 11, a function switching 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.

[0040] As described above with reference to FIG. 1, the main contactor 11 is installed so as to be able to make and break the electrical connection between the DC power source 3 and the inverter 5. The main contactor 11 is closed both when the inverter 5 functions as the vehicle drive device 9 and when the inverter 5 functions as the in-vehicle charging device 10. When the DC power source 3 is not charged and the vehicle is parked, the electrical connection between the DC power source 3 and the inverter 5 can be cut off by opening the main contactor 11. The grid contactor 13 is installed so as to be able to cut off the electrical connection between the external AC power source 4 and the AC-DC converter 1. The function switching contactor 12 can cut off the electrical connection between the first arm 21 and the reactor (here, the neutral point 7N of the coil 7). When the inverter 5 functions as the in-vehicle charging device 10, the function switching contactor 12 is closed and electrically connects the first arm 21 and the reactor. When the coil 7 and the inverter 5 function as the vehicle drive device 9, the function switching contactor 12 is opened.

[0041] In this way, by simply changing the connection form of the inverter 5 and the coil 7, a circuit capable of switching between a function of driving and controlling the rotating electric machine 70 and a function of charging the DC power source 3 with the external AC power source 4 can be realized. That is, the vehicle-mounted charging device 10 can be configured with a simple configuration. As described above, the vehicle-mounted charging device 10 of the present embodiment is a bidirectional power conversion device capable of not only converting AC power to the second DC power, but also converting the second DC power to AC power. By converting the second DC power to AC power, a function of outputting AC power from the DC power source 3 can be realized. When the function of outputting AC power from the DC power source 3 is realized, the main contactor 11 and the function switching contactor 12 are closed. The grid contactor 13 is opened or closed depending on the form of the output destination of the AC current.

[0042] Hereinafter, with reference to FIG. 3 to FIG. 6, the current flow when the DC-DC converter 2 functions as a step-down converter and when it functions as a step-up converter will be described. FIG. 3 and FIG. 4 show the current flow when the DC-DC converter 2 functions as a step-down converter when the DC power source 3 is charged with the power supplied from the external AC power source 4, and FIG. 5 and FIG. 6 show the current flow when the DC-DC converter 2 functions as a step-up converter. For convenience, the current passing through the reactor and the current passing through the second arm are shown by a single line. In reality, the current flows evenly through all of the coils 7 of the multiple phases in the reactor. In addition, all of the multiple upper-stage switching elements 5U of the inverter 5 constituting the second arm are controlled to the same state, and all of the multiple lower-stage switching elements 5L are controlled to the same state. Therefore, the current flows evenly through all of the arms of the multiple phases.

[0043] 3 illustrates the current flow when the DC-DC converter 2 functioning as a step-down converter charges the output capacitor Cs. At this time, the upper-stage switching elements 2U of the first arm are controlled to be on and the lower-stage switching elements 2L are controlled to be off. In addition, the upper-stage switching elements 5U of the inverter 5 constituting the second arm are all controlled to be on and the lower-stage switching elements 5L are all controlled to be off. A current flows from the second DC link capacitor Cd to the output capacitor Cs, charging the output capacitor Cs.

[0044] 4 illustrates the flow of current circulating through the DC-DC converter 2 functioning as a step-down converter. At this time, the upper-side switching elements 2U of the first arm are controlled to be off and the lower-side switching elements 2L are controlled to be on. Also, the upper-side switching elements 5U of the inverter 5 constituting the second arm are all controlled to be on and the lower-side switching elements 5L are all controlled to be off. The current circulates without passing through the second DC link capacitor Cd.

[0045] Fig. 5 illustrates the flow of current circulating through the DC-DC converter 2 functioning as a boost converter. At this time, the upper-side switching element 2U of the first arm is controlled to be off, and the lower-side switching element 2L is controlled to be on. Also, the upper-side switching elements 5U of the inverter 5 constituting the second arm are all controlled to be on, and the lower-side switching elements 5L are all controlled to be off. Due to the continuity of the current flowing through the reactor, the current circulates, and the energy stored in the reactor charges the output capacitor Cs, as will be described later with reference to Fig. 6.

[0046] 6 illustrates the current flow when the DC-DC converter 2 functioning as a boost converter charges the reactor (coil 7). At this time, the upper-stage switching elements 2U of the first arm are controlled to be on and the lower-stage switching elements 2L are controlled to be off. Also, the upper-stage switching elements 5U of the inverter 5 constituting the second arm are all controlled to be off and the lower-stage switching elements 5L are all controlled to be on. Current flows from the second DC link capacitor Cd to the reactor (coil 7) and energy is stored in the reactor (coil 7).

[0047] Because the DC-DC converter 2 has both a step-down function and a step-up function, the in-vehicle charging device 10 with the same hardware configuration can be used, for example, when the rated voltage of the DC power source 3 is both 400 volts and 800 volts.

[0048] The circuit block diagram of Fig. 7 shows a second example of the in-vehicle charging device 10. In the first example, the external AC power supply 4 is a single-phase AC power supply, whereas in the second 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 as a three-phase AC power supply with phases differing by 2π / 3. Corresponding to the three-phase AC power supply, the grid contactor 13 is also configured with three contacts.

[0049] The AC-DC converter 1 of the second example is configured to include a three-phase bridge circuit 18 having three arms corresponding to each of the three phases, similar to the inverter 5, in order to convert power from three-phase AC to DC. An input inductor Li is connected to the connection point of the switching element 1S in the arm of each phase. This three-phase bridge circuit 18 also has a power factor correction function. The other configuration is the same as that described in the first example, so detailed description will be omitted.

[0050] The circuit block diagram of FIG. 8 shows a third example of the in-vehicle charging device 10. In the first example, the external AC power source 4 is a single-phase AC power source, and in the second example, the external AC power source 4 is a multi-phase AC power source. In the third example, both a single-phase and a multi-phase (here, three-phase) external AC power source 4 can be connected. The grid contactor 13 has four contacts, namely, a U-phase contact 13u, a V-phase contact 13v, and a W-phase contact 13w for connecting the three-phase external AC power source 4, and a single-phase contact 13a for connecting the single-phase external AC power source 4. In addition, the AC-DC converter 1 has a three-phase bridge circuit 18 having three arms corresponding to each of the three phases, and a single-phase arm 19 (half-bridge circuit).

[0051] When the external AC power source 4 is a three-phase AC power source as in the second example, three of the four contacts of the grid contactor 13, namely, the U-phase contact 13u, the V-phase contact 13v, and the W-phase contact 13w, are closed, and the single-phase contact 13a is opened. During AC-DC conversion, the three-phase bridge circuit 18 is switched and controlled, and the single-phase arm 19 is not switched and is always maintained in the off state. That is, in this case, the on-board charging device 10 of the third example is equivalent to the on-board charging device 10 of the second example.

[0052] When the external AC power source 4 is a single-phase AC power source as in the first example, one of the three-phase AC power sources corresponds to the single-phase AC power source. Here, it is assumed that the U-phase AC power source 4u indicated by the reference numeral in FIG. 8 is arranged as a single-phase AC power source. Of the four contacts of the grid contactor 13, the single-phase contact 13a and the U-phase contact 13u are closed, and the V-phase contact 13v and the W-phase contact 13w are opened. In the three-phase bridge circuit 18, only the U-phase arm 18u is switched and controlled, and the arms of the other two phases are not switched and are always maintained in an off state. During AC-DC conversion, the single-phase arm 19 and the U-phase arm 18u are switched and controlled. That is, in this case, the vehicle-mounted charging device 10 of the third example is equivalent to the vehicle-mounted charging device 10 of the first example.

[0053] In this way, the on-board charging device 10 of the third example can selectively realize the on-board charging device 10 of the first example and the on-board charging device 10 of the second example. Therefore, the on-board charging device 10 of the same specifications can be applied to many vehicle models, and costs can be easily reduced due to economies of scale in the number of production. In addition, when the connectable external AC power source 4 is limited to a single phase, the grid contactor 13 is sufficient with only the single-phase contact 13a as in the first example. In addition, for the three-phase bridge circuit 18 and the input inductor Li of the AC-DC converter 1, at least the component cost can be reduced by not mounting the switching element 1S or the input inductor Li while using a common circuit board. Therefore, even if the on-board charging device 10 is only compatible with charging at home and only a single-phase AC power source is assumed as the external AC power source 4, for example, the increase in cost of the on-board charging device 10 can be suppressed, and it is possible to realize the on-board charging device 10 of the third example at a cost almost equivalent to that of the on-board charging device 10 of the first example due to the above-mentioned economies of scale.

[0054] The circuit block diagram of Fig. 9 shows a fourth example of the on-board charging device 10. This fourth example is different from the on-board charging device 10 of the third example in that the reactor of the DC-DC converter 2 is configured as a series circuit of a plurality of coils 7 connected in parallel and an inductor Le (an additional inductor or an external inductor) connected to a neutral point 7N of the plurality of coils 7. Naturally, the reactor of the DC-DC converter 2 can be configured in this way in the first, second, and third examples as well.

[0055] As described above, the DC-DC converter 2 also functions as a boost converter. As described above with reference to Figs. 5 and 6, when the DC-DC converter 2 functions as a boost converter, energy is stored in the reactor. The coil 7 of the rotating electric machine 70 is designed to have a high power density, and therefore may have a small inductance as a reactor. By connecting the inductor Le in series with the coil 7, it is possible to set a sufficient inductance for the reactor using the inductance of the inductor Le as well, and it is possible to properly ensure the function as a boost converter.

[0056] However, in a configuration in which 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 from the external AC power supply 4 to the common ground. Since a user or the like may be present near the vehicle while the DC power supply 3 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 4 and the DC power supply 3 are not electrically independent from each other, if a short circuit or other fault occurs in the external AC power supply 4, a large short circuit current may flow to the DC power supply 3 and the in-vehicle device connected to the DC power supply 3.

[0057] 10 and 11, an in-vehicle charging device 10 according to a fifth and sixth example is provided with an insulating circuit, electrically isolating an external AC power source 4 from a DC power source 3. The configuration of the DC-DC converter 2 is similar to that of the first example. An LC filter circuit 1f made up of a filter inductor Lf and a filter capacitor Cf is provided at a connection portion between the AC-DC converter 1 and the external AC power source 4 (between a primary side bridge circuit 111 described later and the external AC power source 4). This does not preclude a configuration in which the LC filter circuit 1f is not provided.

[0058] The AC-DC converter 1 of the on-board charging device 10 of the fifth example shown in FIG. 10 includes 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 dual active bridge (DAB) circuit including a secondary bridge circuit 112 connected to the secondary coil T2. The AC-DC converter 1 can also be said to include a primary circuit 1a and a secondary circuit 1b insulated by the transformer T. The primary circuit 1a includes the primary coil T1, the primary bridge circuit 111, and an LC filter circuit 1f. The primary bridge circuit 111 is a full bridge in which two arms, each of which has two switching elements 11S connected in series, are connected in parallel. The primary coil T1 is connected between the midpoint of one arm (the connection point between the upper-stage switching element 11S and the lower-stage switching element 11S) and the midpoint of the other arm. The primary bridge circuit 111 can also be referred to as an H-bridge including two arms and a primary coil T1 connecting the midpoints of the arms.

[0059] The secondary circuit 1b includes a secondary coil T2, a secondary bridge circuit 112, and a secondary inductor Ls. The secondary bridge circuit 112, which is common to the in-vehicle charging device 10 of a sixth example described later, 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 between the connection point between the upper switching element 12S and the lower switching element 12S via the secondary inductor Ls. The secondary bridge circuit 112 can also be said to be an H bridge including two arms and a secondary coil T2 connecting the midpoints of the arms.

[0060] As shown in FIG. 10, 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 a 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 (input inductor Li) as the primary circuit 1a in the AC-DC converter 1. 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.

[0061] Furthermore, a second DC link capacitor Cd that smoothes the first DC voltage is disposed between the AC-DC converter 1 and the DC-DC converter 2. If the primary side bridge circuit 111 is configured using bidirectional switching elements to construct a current-controlled AC-DC converter, it becomes easy to reduce the capacitance of the second DC link capacitor Cd, and the system can be made more compact.

[0062] 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.

[0063] In this way, according to the fifth example of the in-vehicle charging device 10, since the primary bridge circuit is configured with bidirectional switching elements, the primary bridge circuit can be switched by current control using an inductor, not 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 in-vehicle charging device 10. In addition, the bidirectional switching element is easy to 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 to reduce the system cost. In addition, by providing the transformer T in the AC-DC converter 1, the DC power source 3 and the external AC power source 4 are insulated. Therefore, it is easy to ensure the safety of the user against leakage current from the external AC power source 4. In addition, when a short circuit failure or the like occurs in the external AC power source 4, it is possible to reduce the possibility that a large short-circuit current flows through the DC power source 3 and the in-vehicle device connected to the DC power source 3.

[0064] The circuit block diagram of FIG. 11 shows a sixth example of the in-vehicle charging device 10. The fifth example differs in that the external AC power supply 4 is a single-phase AC power supply, whereas the sixth example differs in that the external AC power supply 4 is a multi-phase AC power supply. Here, as in the second example, the external AC power supply 4 is connected at a neutral point 4N and is configured as a three-phase AC power supply with phases differing by 2π / 3. Corresponding to the three-phase AC power supply, the grid contactor 13 is also configured with three contacts. In the sixth example, an input inductor Li and an input capacitor Ci are provided between the external AC power supply 4 and the primary-side bridge circuit 111. In addition, in the AC-DC converter 1 of the sixth example, in order to convert power from three-phase AC to DC, the primary-side bridge circuit 111 is configured to have three arms corresponding to each of the three phases. Such differences are similar to the differences between the first and second examples, and detailed explanations will be omitted.

[0065] In addition, like the third example that can selectively realize the first and second examples, an in-vehicle charging device 10 that can selectively realize the fifth and sixth examples can also be configured. Those skilled in the art can easily understand this from the relationship between the first, second, and third examples, so a detailed explanation will be omitted. Similarly, as in the fourth example described above, the provision of an inductor Le in the reactor can be applied to the fifth and sixth examples, and to the configuration that can selectively realize the fifth and sixth examples. This can also be easily understood, so a detailed explanation will be omitted.

[0066] FIG. 12 is a circuit block diagram of a conventional charging device 10X referred to in the background art of this specification. The charging device 10X is also configured to share the coil 7 of the rotating electric machine 70, which is a driving force source for the wheels, and the inverter 5 that drives and controls the rotating electric machine 70. The charging device 10X is configured to have a first converter 100 that is an AC-DC converter and a second converter 200 that is a DC-DC converter. The first converter 100 is configured using the coil 7 and the inverter 5, and an external AC power source 4 is connected to a neutral point 7N of the coils 7 of the multiple phases of the rotating electric machine 70. The first converter 100 and the second converter 200 are selectively connected via a function switching contactor 12. When the coil 7 and the inverter 5 are used to drive the wheels, the first contact 12a of the function switching contactor is closed, and when the coil 7 and the inverter 5 are used to charge the DC power source 3, the second contact 12b of the function switching contactor is closed. Since a relatively large current flows through the function switching contactor 12, the component tends to be large in size and the component cost tends to be high.

[0067] As described above with reference to FIG. 2 etc., the in-vehicle charging device 10 of this embodiment also includes a function switching contactor 12 that switches functions between a case where the coil 7 and the inverter 5 are used to drive the wheels and a case where the coil 7 and the inverter 5 are used to charge the DC power source 3. In the in-vehicle charging device 10 of this embodiment, the function switching contactor 12 is configured with one contact that can disconnect the electrical connection between the first arm 21 and the reactor (here, the neutral point 7N of the coil 7). That is, the reactor is disposed between the first arm 21 and the second arm (the inverter 5) via a contactor (function switching contactor 12) that disconnects the electrical connection.

[0068] The contactor (function switching contactor 12) that switches the function between when the coil 7 and the inverter 5 are used to drive the wheels and when the coil 7 and the inverter 5 are used to charge the DC power source 3 has only one contact, so that the size of the contactor can be easily kept small. The contactor connects the first arm 21 to the neutral point 7N of the coil 7 when the coil 7 is used to charge the DC power source 3, and opens when the coil 7 is used to drive the wheels. Therefore, when a large current flows due to the driving of the wheels, no current flows through the contactor, and the specification of the current that the contactor can tolerate can be easily kept low. Therefore, the size of the contactor can be easily kept small, and the cost can also be easily suppressed. That is, the in-vehicle charging device 10 can be easily configured while suppressing an increase in system cost.

[0069] In addition, the second converter 200 that performs DC-DC conversion in the charging device 10X only has a step-down function. As described above, some DC power sources mounted on vehicles to supply power to a rotating electric machine that drives the wheels have different rated voltages. Even for the same vehicle model, the rated voltage of the DC power source may differ depending on the grade. For example, in a higher grade, it may be necessary to boost the voltage of the DC power provided by the first converter 100. If in-vehicle charging devices with different configurations are mounted depending on the grade, economies of scale cannot be obtained, and cost reduction of the in-vehicle charging device is limited.

[0070] In this embodiment, the in-vehicle charging device 10 is configured with a DC-DC converter 2 having a step-up / step-down function, so that the same hardware can be used and the same in-vehicle charging device 10 can be deployed in a variety of grades and vehicle models by changing the control form (e.g., software such as a program). [Explanation of symbols]

[0071] 1: AC-DC converter, 2: DC-DC converter, 3: DC power source, 4: external AC power source, 5: inverter, 7: coil, 7N: neutral point, 10: on-board charging device, 12: function switching contactor (contactor), 21: first arm, 70: rotating electric machine, 111: primary bridge circuit, 112: secondary bridge circuit, T: transformer, T1: primary coil, T2: secondary coil

Claims

1. An on-board charging device is mounted on a vehicle including a rotating electric machine having multiple 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 direct current and multiple phase alternating current, and a DC power source that is connected to the rotating electric machine via the inverter, and charges the DC power source with power supplied from an external AC power source, an AC / DC converter that converts power between AC power on the side of the external AC power supply and a first DC power; a DC-DC converter that converts power between the first DC power and a second DC power on the side of the DC power source, the DC-DC converter comprises an H-bridge circuit including a first arm on the AC-DC converter side, a second arm on the DC power supply side, and a reactor disposed between the first arm and the second arm; The reactor is configured using a plurality of the coils, The second arm is configured using the inverter.

2. the AC-DC converter is an AC-DC step-up converter; The on-board charging device according to claim 1 , wherein the DC-DC converter functions as a DC-DC step-up converter or a DC-DC step-down converter depending on a rated voltage of the DC power source.

3. The AC / DC converter comprises: 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:

3. The vehicle-mounted charging device according to claim 1, wherein the primary bridge circuit is configured with bidirectional switching elements.

4. The on-board charging device according to claim 1 , wherein the reactor is disposed between the first arm and the second arm via a contactor that establishes or breaks an electrical connection.

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