Onboard charger

Abstract

To provide an onboard charger that can also use a vehicle driving device, charge an onboard DC power supply with an external AC power supply and output AC power from the DC 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 AC-DC converter 1 includes a current source active rectifier 17 having a power factor improvement function. The DC-DC converter 2 includes a chopper circuit including a reactor disposed on a side of the AC-DC converter 1 and a half-bridge circuit disposed on the side of the DC power supply 3. The reactor is configured using a plurality of coils 7, the half-bridge circuit is configured using an inverter 5, and the current source active rectifier 17 is configured using a bidirectional switching element.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Christelle Saber et al. have published a paper on an on-board charging device for charging batteries (DC power sources) for electric vehicles. Saber et al. have considered power factor correction (PFC) in on-board chargers that use components from a vehicle drive system (traction power train) to reduce costs. As shown in FIG. 16, the on-board charging device considered by Saber et al. includes a one-way current source active rectifier 17 (CSAR) with a step-down function at the input stage (AC-DC converter 1) from an external AC power source 4, and includes a step-up converter at the output stage (DC-DC converter 2) to the DC power source 3 following the CSAR. That is, the on-board charging device disclosed includes an AC-DC step-down converter and a DC-DC step-up converter arranged in this order from the external AC power source 4 toward the DC power source 3.

[0003] In the paper, Saber et al. consider an in-vehicle charging device that receives power from a single-phase external AC power source 4. Published Japanese Translation of PCT International Publication No. 2011-526775 (family: US Patent Application Publication No. 2012 / 0286740) discloses an example of an in-vehicle charging device that receives power from a three-phase external AC power source 4, as shown in Fig. 17. This in-vehicle charging device also has a configuration in which an AC-DC step-down converter and a DC-DC step-up converter are arranged in this order from the external AC power source 4 to the DC power source 3. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2011-526775 [Non-patent literature]

[0005] [Non-Patent Document 1] Christelle Saber, Denis Labrousse, Bertrand Revol, and Alain Gascher “Challenges Facing PFC of a Single-Phase On-Board Charger for Electric Vehicles Based on a Current Source Active Rectifier Input Stage”, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol.31, No.9, September 2016, P.6192-6202 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, it has been proposed to use the DC power source of an electric vehicle or a hybrid vehicle as an emergency AC power source in the event of a disaster, etc. However, the on-board charging device described above with reference to Fig. 16 and Fig. 17 only supports one-way power supply from an external AC power source to a DC power source.

[0007] In view of the above background, it is desirable to provide an on-board charging device that also utilizes a vehicle drive device, charges an on-board DC power supply from an external AC power supply, and outputs AC power from the DC power supply. [Means for solving the problem]

[0008] 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, the on-board charging device including an AC / DC converter which converts power between AC power on the side of the external AC power source 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 side of the DC power source, the AC / DC converter including a current source active rectifier having a power factor correction function, the DC / DC converter including a chopper circuit including a reactor arranged on the side of the AC / DC converter and a half-bridge circuit arranged on the side of the DC power source, the reactor being configured using a plurality of the coils, the half-bridge circuit being configured using the inverter, and the current source active rectifier being configured using a bidirectional switching element.

[0009] According to this configuration, the current source active rectifier having a power factor correction function in the AC-DC converter is configured by a bidirectional switching element. That is, the current source active rectifier is configured by using a bidirectional switching element as a switching element. The bidirectional switching element is an element that can pass a current in both directions, and has the same withstand voltage for both positive and negative voltages. Therefore, it is easy to construct an AC-DC converter equipped with a current-controlled active rectifier circuit. 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, and it is possible to reduce component costs and suppress the increase in size of the device. In addition, the current source active rectifier configured by using a bidirectional switching element is a current source active rectifier capable of bidirectional power conversion. Therefore, not only AC to DC power conversion but also DC to AC power conversion is possible. Therefore, it is also possible to use the DC power source of an electric vehicle or a hybrid vehicle as an emergency AC power source. Thus, according to this configuration, it is possible to provide an on-board charging device that also utilizes a vehicle drive device, charges an on-board DC power supply from an external AC power supply, and outputs AC power from the DC power supply.

[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] FIG. 1 is a diagram showing a positive current loop when charging an output capacitor in an on-board charging device that functions as an AC-DC step-down converter when charging a DC power source. [Figure 4] Diagram showing the positive current return loop in an on-board charging device functioning as an AC-DC step-down converter. [Diagram 5] FIG. 1 is a diagram showing a negative current loop when charging an output capacitor in an on-board charging device that functions as an AC-DC step-down converter when charging a DC power source. [Figure 6] A diagram showing a negative current return loop in an on-board charging device functioning as an AC-DC step-down converter. [Figure 7] FIG. 1 is a diagram showing a positive current loop when charging a reactor in an on-board charging device that functions as an AC-DC boost converter when charging a DC power source. [Figure 8] A diagram showing the positive current return loop in an on-board charging device functioning as an AC-DC boost converter. [Figure 9] FIG. 1 is a diagram showing a negative current loop when charging a reactor in an on-board charging device that functions as an AC-DC boost converter when charging a DC power source. [Figure 10] A diagram showing a negative current return loop in an on-board charging device functioning as an AC-DC boost converter. [Figure 11] 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 12] 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 13] FIG. 13 is a diagram showing an example of a positive current loop when the on-board charging device of the third example is supplied with power from a three-phase external DC power supply. [Figure 14] FIG. 13 is a diagram showing an example of a return loop of a positive current in the on-board charging device of the third example. [Figure 15] FIG. 13 is a diagram showing an example of a positive current loop when the on-board charging device of the third example is supplied with power from a single-phase external DC power supply. [Figure 16] A circuit block diagram showing a conventional example of a charging device that uses a drive control system for a rotating electrical machine to charge a DC power source with power from a single-phase AC external power source. [Figure 17] A circuit block diagram showing a conventional example of a charging device that uses a drive control system for a rotating electrical machine to charge a DC power source with power from a three-phase AC external power source. 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. 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. The DC link capacitor 6 is also shared as an output capacitor Cs of the vehicle-mounted charging device 10. All or at least some of the control devices (not shown) that control the switching elements, contactors, etc. provided in the vehicle-mounted charging device 10 may be shared with the control device 80 that controls the vehicle drive device 9.

[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 (which may also be called legs). Each arm is formed by connecting an upper-stage switching element arranged on the positive side and a lower-stage switching element arranged on the negative side in series. The midpoint of each arm, that is, the connection point between the upper-stage switching element and the lower-stage switching element, is connected to the respective coil 7. Specifically, the midpoint of the U-phase arm is connected to the U-phase coil 7u, the midpoint of the V-phase arm is connected to the V-phase coil 7v, and the midpoint of the W-phase arm is connected to the W-phase coil 7w.

[0016] 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.

[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 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.

[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. 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.

[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 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.

[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 (program).

[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, 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.

[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] FIG. 16 shows a conventional vehicle-mounted charging device (first charging device 10X) also exemplified in the background art. The same reference numerals are used for parts corresponding to the vehicle-mounted charging device 10 of the present embodiment. This first charging device 10X also uses a power train (traction power train) for driving the wheels. As with the vehicle-mounted charging device 10 of the present embodiment, the first charging device 10X also uses an inverter 5 (traction inverter for driving) and a coil 7 (windings of a rotating electric machine) in the DC-DC converter 2, which is an output stage to the DC power source 3. The coil 7 is used as a reactor (filtering inductor) as with the vehicle-mounted charging device 10 of the present embodiment. The inverter 5 having three-phase arms (also synonymous with legs) has upper-stage switching elements collectively switched and lower-stage switching elements collectively switched so as to appear as one arm.

[0026] As shown in FIG. 16, the first charging device 10X includes a unidirectional current source active rectifier 17 (CSAR: Current Source Active Rectifier) ​​having a step-down function in the AC-DC converter 1, which is an input stage from the external AC power source 4. The current source active rectifier includes a full bridge circuit using switching elements, and is configured as a totem-pole type power factor correction circuit. One arm of this full bridge circuit is configured by sequentially connecting, from the positive pole side to the negative pole side of the DC, one diode with a cathode connected to the positive pole side, two switching elements with freewheel diodes connected in parallel with the forward direction from the positive pole side to the negative pole side, and one diode with an anode connected to the negative pole side. Between the external AC power source 4 and the current source active rectifier 17, a filter 1f (inductor-capacitor filter) consisting of a filter inductor Lf and a filter capacitor Cf is arranged. In addition, between the filter 1f and the external AC power source 4, a differential mode inductor Lg is arranged.

[0027] Although detailed description is omitted, the same applies to an on-vehicle charging device (second charging device 10Y) shown in FIG. 17 that charges a DC power source 3 with power from a three-phase external AC power source 4.

[0028] In this embodiment, an in-vehicle charging device 10 is mounted on a vehicle equipped with a rotating electric machine 70 that is a driving force source for wheels and includes a multi-phase coil 7 connected to a neutral point 7N, an inverter 5 that converts power between DC and multi-phase AC, and a DC power source 3 that is connected to the rotating electric machine 70 via the inverter 5, and charges the DC power source 3 with power supplied from an external AC power source 4. That is, as shown in FIG. 2, the in-vehicle charging device 10 includes an AC-DC converter 1 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 2 that converts power between the first DC power and a second DC power on the side of the DC power source 3. The AC-DC converter 1 includes a current source active rectifier 17 having a power factor correction function, and the DC-DC converter 2 includes a chopper circuit including a reactor arranged on the side of the AC-DC converter 1 and a half-bridge circuit arranged on the side of the DC power source 3. In the first example shown in FIG. 2, the current source active rectifier 17 is configured by a full bridge circuit including four switching elements 1S.

[0029] In the DC-DC converter 2, a reactor is configured using a plurality of coils 7, and a half-bridge circuit is configured using an inverter 5. Specifically, the coils 7 of multiple phases connected in parallel appear as one coil, and together with an inductor Le described later, they configure a reactor. Furthermore, the arms of each phase connected in parallel of the inverter 5 appear as one phase arm, and configure a half-bridge circuit. The neutral point 7N of the coils 7 is connected to the AC-DC converter 1 via the inductor Le. The neutral point 7N may be connected to the AC-DC converter 1 without providing the inductor Le. The end of the coils 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 between the upper-stage switching element and the lower-stage switching element of each arm). The reactor may be called a choke coil.

[0030] Moreover, the current source active rectifier 17 of the AC-DC converter 1 is composed of a bidirectional switching device. Specifically, one arm of the full bridge circuit constituting the current source active rectifier 17 is composed of two bidirectional switching devices connected in series from the positive pole side to the negative pole side of the DC current. The bidirectional switching device is an element that can pass current in both directions, and has the same withstand voltage against both positive and negative polarity voltages. For this reason, it is easy to construct the AC-DC converter 1 equipped with a current-controlled active rectifier circuit. 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.

[0031] Moreover, this current source active rectifier 17 is not a unidirectional current source active rectifier like the first charging device 10X illustrated in Fig. 16, but a bidirectional current source active rectifier. Therefore, not only AC to DC power conversion but also DC to AC power conversion is possible. Therefore, the DC power source 3 of an electric vehicle or a hybrid vehicle can be used as an emergency AC power source.

[0032] FIG. 2 illustrates an example in which a filter 1f (inductor-capacitor filter) composed of a filter inductor Lf and a filter capacitor Cf is disposed between the external AC power supply 4 and the current source active rectifier 17, similar to the first charging device 10X. Also, an example in which a differential mode inductor Lg is disposed between the filter 1f and the external AC power supply 4. Furthermore, a freewheel diode (DC link freewheel diode Dfw) is disposed between the AC-DC converter 1 and the DC-DC converter 2, with the direction from the negative pole to the positive pole of the first DC power as the forward direction.

[0033] 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 and the vehicle-mounted device connected to the DC power supply 3. However, in this embodiment, by providing the DC link freewheel diode Dfw, even if a short circuit occurs between the positive and negative poles at the output terminal of the AC-DC converter 1 (or the input terminal of the DC-DC converter 2), the current flowing from the positive pole to the negative pole can be cut off by the DC link freewheel diode Dfw. Therefore, even if an insulating circuit using, for example, a transformer is not provided in the vehicle-mounted charging device 10, it is possible to prepare for a short circuit or the like of the external AC power supply 4 as described above. That is, an increase in the circuit size of the vehicle-mounted charging device 10 can be suppressed.

[0034] The in-vehicle charging device 10 of this embodiment, which is configured to perform bidirectional power conversion from AC to DC (second DC power) and from DC (second DC power) to AC, can be said to be configured as follows. When the in-vehicle charging device 10 charges the DC power source 3 from the external AC power source 4, the AC-DC converter 1 functions as a unity power factor AC-DC step-down converter (AC / DC Buck Converter UPF (Unity Power Factor)), and the DC-DC converter 2 functions as a DC / DC boost converter. When the in-vehicle charging device 10 functions as an emergency AC power source that outputs AC power using power stored in the DC power source 3, the DC-DC converter 2 functions as a DC / DC step-down converter (DC / DC Buck Converter), and the AC-DC converter 1 functions as a unity power factor DC-AC boost converter (DC / AC Boost Converter UPF).

[0035] In this embodiment, when the in-vehicle charging device 10 charges the DC power supply 3 with the external AC power supply 4, the DC / DC converter 2 can also function as a DC / DC buck converter. In other words, the in-vehicle charging device 10 as a whole can have both the function of an AC / DC buck converter and the function of an AC / DC boost converter as a function of power conversion from AC power to second DC power (battery power).

[0036] The DC power source 3 mounted on a 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, a higher grade may be equipped with a DC power source 3 with a higher rated voltage 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, a boost is required in the DC-DC converter 2. If an on-vehicle charging device 10 with a different configuration is mounted depending on the vehicle, economies of scale cannot be obtained, and the reduction in the cost of the on-vehicle charging device 10 is limited. However, by configuring the DC-DC converter 2 with a boost / buck function, the same hardware can be used and the same on-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). For example, the on-vehicle charging device 10 with the same hardware configuration can be used in both cases where the rated voltage of the DC power source 3 is 400 volts and 800 volts.

[0037] Also, as described above, in this embodiment, the reactor of the DC-DC converter 2 is composed of a series circuit of a plurality of coils 7 connected in parallel and an inductor Le (additional inductor, or external inductor) connected to the neutral point 7N of the plurality of coils 7.

[0038] 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.

[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 main contactor 11 is opened to cut off the electrical connection between the DC power source 3 and the inverter 5. 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 is able to cut off the electrical connection between the AC-DC converter 1 and the reactor (here, the inductor Le). In other words, the reactor is disposed between the AC-DC converter 1 and the inverter 5 via the function switching contactor 12 which makes and breaks the electrical connection. When the inverter 5 functions as the in-vehicle charging device 10, the function switching contactor 12 is closed to electrically connect the AC-DC converter 1 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] The following describes current loops by way of example for the case where the on-board charging device 10 functions as an AC / DC buck converter as a whole and the case where the on-board charging device 10 functions as an AC / DC boost converter. Figures 3 to 6 show current loops when the on-board charging device 10 functions as an AC / DC buck converter, and Figures 7 to 10 show current loops when the on-board charging device 10 functions as an AC / DC boost converter.

[0043] In describing the current loop, the control states of the switching elements of the full bridge circuit of the current source active rectifier 17 of the AC-DC converter 1 and the half bridge circuit realized by the inverter 5 of the DC-DC converter 2 are also shown. The full bridge circuit of the current source active rectifier 17 includes a first arm in which a first switch S1 and a second switch S2 are connected in series in the order shown from the positive pole side to the negative pole side of the DC, and a second arm in which a third switch S3 and a fourth switch S4 are connected in series in the order shown from the positive pole side to the negative pole side of the DC. The apparent half bridge circuit realized by the inverter 5 is configured by connecting a fifth switch S5 and a sixth switch S6 in series in the order shown from the positive pole side to the negative pole side of the DC.

[0044] Table 1 below shows the functions of the on-board charging device 10 shown in Figs. 3 to 10, the direction of the current loop, the operation phase, and the control state (on state / off state) of the switching element. In the table, "Fig." shows the number of the drawing attached to this specification, and "Function" shows whether the function of the on-board charging device 10 is an AC / DC boost converter or an AC / DC buck converter. Also, "Loop" shows whether the current loop is a positive current loop (Posi.) or a negative current loop (Nega.). "Phase" shows the action of the current loop, "C Charging" shows the state in which the output capacitor is charged, "L Charging" shows the state in which the reactor (inductor Le, coil 7) is charged, and "Free Wheeling" shows the state in which the current is circulating. "S1" to "S6" show the first switch S1 to the sixth switch S6 described above, "ON" shows the state in which the switch is controlled to be in the on state, and "OFF" shows the state in which the switch is controlled to be in the off state.

[0045] [Table 1]

[0046] FIG. 3 shows a positive current loop when charging an output capacitor Cs (DC link capacitor 6) connected in parallel to a DC power source 3 in an on-board charging device 10 that functions as an AC-DC step-down converter when charging the DC power source 3. A current from an external AC power source 4 (conveniently, the positive side of the external AC power source 4) forms a current loop that passes through an input inductor Li, a first switch S1 in an ON state, a reactor (inductor Le, coil 7), a freewheel diode connected in inverse parallel to a fifth switch S5 in an OFF state, an output capacitor Cs, and a fourth switch S4 in an ON state, and returns to the external AC power source 4 (conveniently, the negative side of the external AC power source 4). The output capacitor Cs is charged by this current loop. Note that, depending on the structure of the fifth switch S5, the freewheel diode may not be provided, and the current flowing through the freewheel diode may be passed by a body diode of a switching element or a reverse conduction function of the switching element. The same applies to the following description.

[0047] 4 shows a return loop of a positive current in the on-board charging device 10 functioning as an AC-DC step-down converter. In this phase, the first switch S1 and the second switch S2 are in an OFF state, and the connection between the AC-DC converter 1 and the DC-DC converter 2 is interrupted. The current returning from the output capacitor Cs to the external AC power supply 4 returns to the DC-DC converter 2 through the DC link freewheel diode Dfw. That is, the current flows in the order of the reactor (inductor Le, coil 7), the freewheel diode connected in anti-parallel to the fifth switch S5 in an OFF state, the output capacitor Cs, the DC link freewheel diode Dfw, and the reactor, and returns inside the DC-DC converter 2.

[0048] 5 shows a negative current loop when charging an output capacitor Cs connected in parallel to a DC power supply 3 in an on-board charging device 10 that functions as an AC-DC step-down converter when charging the DC power supply 3. A current from the external AC power supply 4 (conveniently, the negative side of the external AC power supply 4) forms a current loop that passes through the third switch S3 in an ON state, the reactor (inductor Le, coil 7), the freewheel diode connected in inverse parallel to the fifth switch S5 in an OFF state, the output capacitor Cs, the second switch S2 in an ON state, and the input inductor Li, and returns to the external AC power supply 4 (conveniently, the positive side of the external AC power supply 4). The output capacitor Cs is charged by this current loop.

[0049] 6 shows a return loop of a negative current in the on-board charging device 10 functioning as an AC-DC step-down converter. In this phase, the first switch S1 and the second switch S2 are in an OFF state, and the connection between the AC-DC converter 1 and the DC-DC converter 2 is interrupted. The current returning from the output capacitor Cs to the external AC power supply 4 returns to the DC-DC converter 2 through the DC link freewheel diode Dfw. That is, the current flows in the order of the reactor (inductor Le, coil 7), the freewheel diode connected in anti-parallel to the fifth switch S5 in an OFF state, the output capacitor Cs, the DC link freewheel diode Dfw, and the reactor, and returns inside the DC-DC converter 2.

[0050] 7 shows a positive current loop when charging a reactor in an on-board charging device 10 that functions as an AC-DC boost converter when charging a DC power source 3. A current from an external AC power source 4 (conveniently, the positive side of the external AC power source 4) forms a current loop that passes through the input inductor Li, the first switch S1 in an ON state, the reactor (inductor Le, coil 7), the sixth switch S6 in an ON state, and the fourth switch S4 in an ON state, and returns to the external AC power source 4 (conveniently, the negative side of the external AC power source 4). The reactor is charged by this current loop.

[0051] 8 shows a return loop of a positive current in the on-board charging device 10 functioning as an AC-DC boost converter. In this phase, the first switch S1 and the second switch S2 are in an OFF state, and the connection between the AC-DC converter 1 and the DC-DC converter 2 is interrupted. The fifth switch S5 and the sixth switch S6 are both controlled to an OFF state, and the current flowing through the reactor (inductor Le, coil 7) flows in the order of the freewheel diode connected in anti-parallel to the fifth switch S5 in the OFF state, the output capacitor Cs, the DC link freewheel diode Dfw, and the reactor, and returns inside the DC-DC converter 2. The energy stored in the reactor is supplied to the output capacitor Cs.

[0052] 9 shows a negative current loop when a reactor is charged to the DC power supply 3 in the on-board charging device 10 that functions as an AC-DC boost converter when charging the DC power supply 3. A current from the external AC power supply 4 (conveniently, the negative side of the external AC power supply 4) forms a current loop that passes through the third switch S3 in the on state, the reactor (inductor Le, coil 7), the sixth switch S6 in the on state, the second switch S2 in the on state, and the input inductor Li, and returns to the external AC power supply 4 (conveniently, the positive side of the external AC power supply 4). The reactor is charged by this current loop.

[0053] 10 shows a return loop of a negative current in the on-board charging device 10 functioning as an AC-DC boost converter. In this phase, the first switch S1 and the second switch S2 are in an OFF state, and the connection between the AC-DC converter 1 and the DC-DC converter 2 is interrupted. The fifth switch S5 and the sixth switch S6 are both controlled to an OFF state, and the current flowing through the reactor (inductor Le, coil 7) flows in the order of the freewheel diode connected in anti-parallel to the fifth switch S5 in the OFF state, the output capacitor Cs, the DC link freewheel diode Dfw, and the reactor, and returns inside the DC-DC converter 2. The energy stored in the reactor is supplied to the output capacitor Cs.

[0054] In this way, since the vehicle-mounted charging device 10 has a step-down function and a step-up function for converting AC power to the second DC power (battery power), the vehicle-mounted charging device 10 with the same hardware configuration can be used in both cases where the rated voltage of the DC power source 3 is 400 volts and where it is 800 volts, for example.

[0055] The circuit block diagram in Fig. 11 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.

[0056] 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. This three-phase bridge circuit 18 also includes a current source active rectifier having a power factor correction function. The other configuration is the same as that described in the first example, so detailed description will be omitted.

[0057] The circuit block diagram of FIG. 12 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, whereas in the third example, both a single-phase and a multi-phase (here, three-phase) external AC power source 4 can be connected. That is, the in-vehicle charging device 10 of the third example can selectively connect an external AC power source 4 that supplies a single-phase AC power source and an external AC power source 4 that supplies a multi-phase AC power source. 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).

[0058] 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.

[0059] 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. 12 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 other two phase arms 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.

[0060] 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 of the AC-DC converter 1, at least the component cost can be reduced by using a common circuit board and not mounting a switching element. 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 the on-board charging device 10 of the third example may be realized 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.

[0061] Fig. 13 shows an example of a current loop when the on-board charging device 10 of the third example is supplied with power from a three-phase external AC power supply 4. Fig. 13 shows a current loop at phase Q. A positive current flows in phase U, and a negative current flows in phase V and phase W. The current path, particularly the current path through the DC-DC converter 2, is similar to the form described above with reference to Fig. 3, and therefore a detailed description thereof will be omitted.

[0062] Fig. 14 shows an example of a current return loop in the third example of the on-board charging device 10. The current path, particularly the current path through the DC-DC converter 2, is similar to that described above with reference to Fig. 4, and therefore a detailed description thereof will be omitted.

[0063] Fig. 15 shows an example of a positive current loop when the in-vehicle charging device 10 of the third example is supplied with power from a single-phase external AC power supply 4. The current path is as described above with reference to Fig. 3, so a detailed description thereof will be omitted. Also, the return loop is as described above with reference to Fig. 4, so illustration and detailed description thereof will be omitted. [Explanation of symbols]

[0064] 1: AC-DC converter, 2: DC-DC converter, 3: DC power supply, 4: external AC power supply, 4N: neutral point, 5: inverter, 7: coil, 10: on-board charging device, 17: current source active rectifier, 70: rotating electric machine, Le: inductor

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 AC-DC converter comprises a current source active rectifier with power factor correction; the DC-DC converter includes a chopper circuit including a reactor arranged on the AC-DC converter side and a half-bridge circuit arranged on the DC power supply side; The reactor is configured using a plurality of the coils, The half-bridge circuit is configured using the inverter, An in-vehicle charging device, wherein the current source active rectifier is configured using a bidirectional switching element.

2. 2. The on-board charging device according to claim 1, wherein the reactor is configured by a series circuit of a plurality of the coils connected in parallel and an inductor connected to the neutral point of the plurality of the coils.

3. The on-board charging device according to claim 1 , wherein the reactor is disposed between the AC / DC converter and the inverter via a contactor that makes and breaks an electrical connection.

4. The on-board charging device according to claim 1 , wherein the external AC power supply that supplies a single-phase AC power supply and the external AC power supply that supplies a multi-phase AC power supply are selectively connectable to the on-board charging device.

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