JP2024115455A - On-board charging equipment - Google Patents

Abstract

To provide an on-vehicle charging apparatus that can charge a DC power source of a vehicular driving device with electric power from an external AC power source, with high efficiency, while utilizing a coil of a rotary electric machine and an inverter.SOLUTION: An on-vehicle charging apparatus comprises an AC-DC converter that converts AC power from an external AC power source to DC power, a DC-DC converter, and a control device, where one of the converters is configured using an inverter of a vehicular driving device and multi-phase coils, and a smooth capacitor is arranged between the converters. The control device executes constant power charging control so that charging power Pbat is constant until a terminal voltage Vbat of a DC power source reaches a second voltage Vbat_s from a state where the terminal voltage is lower than the second voltage Vbat_s which is lower than a voltage Vbat_s in a fully charged state. In the constant power charging control, the control device executes variable DC voltage control so that a terminal voltage Vdc of the smooth capacitor increases in accordance with an increase in the terminal voltage Vbat of the DC power source.SELECTED DRAWING: Figure 4

Description

The present invention relates to an on-board charging device.

JP 2015-201382 A discloses constant current/constant voltage charging control as a charging control method when charging a DC power source (secondary battery) with power supplied from an external power source. Specifically, when the state of charge (SOC) of the DC power source is low, the DC power source is charged by constant current charging control that supplies a constant current to the DC power source. As charging by constant current charging control progresses, the value of the SOC increases, and the terminal voltage (battery voltage) of the DC power source also increases. When the SOC increases to a preset value or the battery voltage increases to a preset value, the control method is switched from constant current charging control to constant voltage charging control. In constant voltage charging control, charging continues while keeping the voltage applied to the DC power source constant. Since the voltage applied to the DC power source is kept constant, the charging current gradually decreases, and when the charging current decreases to a preset current value, charging is terminated. Constant current/constant voltage charging control allows the DC power source to be charged in a relatively short time while preventing overcharging (overvoltage) of the DC power source.

JP 2015-201382 A

For example, vehicles equipped with a rotating electric machine as a driving force source for wheels, such as electric vehicles and hybrid vehicles, may be equipped with an on-board charging device (on-board charger) that charges a DC power source while mounted on the vehicle. In this case, a part of the circuit constituting the on-board charging device may be configured using a driving circuit of the rotating electric machine including a coil (stator coil) of the rotating electric machine. In many cases, an inverter that converts power between DC and AC is arranged between the rotating electric machine and the DC power source, and a smoothing capacitor that smoothes the DC voltage is arranged between the inverter and the DC power source. When an inverter and a smoothing capacitor are included in the driving circuit of the rotating electric machine used in the on-board charging device, the terminal voltage (DC link voltage) of the smoothing capacitor is often maintained at a constant voltage value in constant current constant voltage charging. On the other hand, the terminal voltage (battery voltage) of the DC power source is low at the start of charging control when the SOC is low, and increases as the constant current charging control progresses. Therefore, at the start of charging control, the voltage difference between the DC link voltage and the battery voltage is large, and losses such as switching losses in the on-board charging device tend to be large. In other words, conventional constant current, constant voltage charging control tends to result in large losses in the on-board charging device.

In addition, in constant current charging control, the battery voltage increases as the control progresses. Therefore, the charging power based on the current flowing through the DC power supply and the battery voltage is not constant, but increases as the control progresses. The charging power is small at the beginning of the charging control, and increases as the constant current charging control progresses. In other words, the DC power supply is not charged with the maximum allowable charging power, so the charging time tends to be long. Therefore, in the conventional constant current constant voltage system, there is room for improvement in the charging efficiency and the system efficiency of the on-board charging device, including the loss of the switching element described above.

In light of the above, it is desirable to realize an on-board charging device that can charge the DC power supply of a vehicle drive device equipped with a rotating electric machine, an inverter, and a DC power supply with high efficiency using the coil of the rotating electric machine and the inverter with power from an external AC power supply.

In view of the above, an on-board charging device is an on-board charging device that charges the DC power supply of a vehicle drive device, which includes a rotating electric machine that serves as a driving force source for wheels, an inverter that converts power between DC and multiple-phase AC, and a DC power supply connected to the inverter, with power supplied from a single-phase external AC power supply, and is equipped with an AC-DC converter that converts AC power from the external AC power supply into DC power, a DC-DC converter that converts the AC power from the external AC power supply into DC power, a smoothing capacitor that is disposed between the AC-DC converter and the DC-DC converter and that smooths the voltage of the DC power converted by the AC-DC converter, and a control device that controls the AC-DC converter and the DC-DC converter, and one of the AC-DC converter and the DC-DC converter is connected to the inverter. and a plurality of phases of the coils, the AC side terminal of the AC-DC converter is connected to the external AC power source, the DC side terminal of the AC-DC converter is connected to a first terminal of the DC-DC converter, and a second terminal different from the first terminal of the DC-DC converter is connected to the DC power source, and the control device sets the terminal voltage of the DC power source when the DC power source is fully charged as a first voltage, sets a voltage that is preset lower than the first voltage as a second voltage, and performs constant power charging control as charging control until the terminal voltage of the DC power source reaches the second voltage from a state lower than the second voltage, so that the charging power based on the current flowing through the DC power source and the terminal voltage of the DC power source is constant, and in the constant power charging control, variable DC voltage control is performed so that the terminal voltage of the smoothing capacitor increases in response to an increase in the terminal voltage of the DC power source.

According to this configuration, constant power charging control is executed so that the charging power is constant from a state in which the state of charge (SOC) of the DC power source is low and the terminal voltage of the DC power source is less than the second voltage until the terminal voltage reaches the second voltage. Therefore, the DC power source can be charged with the maximum allowable charging power, so that the charging time can be shortened. In addition, variable DC voltage control is also executed during execution of the constant power charging control. Since the terminal voltage of the smoothing capacitor is controlled to rise in the same way as the terminal voltage of the DC power source, which rises from less than the second voltage toward the second voltage as a result of execution of the constant power charging control, the voltage difference between the input side and the output side of the DC-DC converter is easily kept relatively small compared to the case in which the terminal voltage of the smoothing capacitor is held at a constant voltage higher than the second voltage. As a result, it is easy to reduce losses such as switching losses in the on-board charging device. In this way, with this configuration, it is possible to realize an on-board charging device that can charge the DC power supply of a vehicle drive device equipped with a rotating electric machine, an inverter, and a DC power supply with high efficiency using the coil of the rotating electric machine and the inverter with power from an external AC power supply.

Further features and advantages of the on-board charging device will become apparent from the following description of exemplary, non-limiting embodiments, which are illustrated in the drawings.

Schematic circuit block diagram of a drive control system for a rotating electric machine Schematic block diagram of the system configuration of an in-vehicle charging device A circuit block diagram showing an example of an on-board charging device using a drive control system for a rotating electric machine. Graph showing an example of charging control Graph showing a comparison example of charging control Schematic control block diagram of AC-DC converter Schematic control block diagram of a DC-DC converter FIG. 1 is a diagram showing an example of a current path in precharge control; FIG. 1 is a diagram showing a comparative example of a current path in precharge control; FIG. 13 is a diagram showing another comparative example of a current path in precharge control; A circuit block diagram showing another example of an on-board charging device using a drive control system for a rotating electric machine.

Hereinafter, an embodiment of the vehicle-mounted charging device will be described with reference to the drawings. The vehicle-mounted charging device 10 is a device that charges the DC power source 3 provided in the vehicle drive device 9 as shown in FIG. 1 while mounted on the vehicle. FIG. 1 is a schematic circuit block diagram of a drive control system for a rotating electric machine 70 included in the vehicle drive device 9, and FIG. 2 is a schematic block diagram of the system configuration of the vehicle-mounted charging device 10. As shown in FIG. 1, the vehicle drive device 9 of this embodiment includes a rotating electric machine 70 that serves as a driving force source for wheels of a hybrid vehicle, an electric vehicle, etc., an inverter 5 that converts power between DC and multiple phase AC, and a DC power source 3 connected to the inverter 5. Note that this does not prevent the vehicle drive device 9 from also including other driving force sources such as an internal combustion engine (not shown) in addition to the rotating electric machine 70. As shown in FIG. 2, the vehicle-mounted charging device 10 is a device that charges the DC power source 3 of the vehicle drive device 9 with power supplied from a single-phase external AC power source 4 (grid power source), and is a device that is so-called an onboard charger. In this embodiment, the vehicle-mounted charging device 10 is configured to share some parts with the vehicle drive device 9. Specifically, the inverter 5 and the coil 7 of the rotating electric machine 70 are shared. Preferably, as described below, the control device 8 that drives the inverter 5 and the smoothing capacitor (DC link capacitor 6) that smoothes the DC voltage are also shared.

As shown in FIG. 1, the vehicle drive device 9 includes a control device 8 that controls a rotating electric machine 70 that serves as a driving force source for the vehicle, and the control device 8 drives and controls the rotating electric machine 70 by performing current feedback control. The rotating electric machine 70 to be driven is an interior permanent magnet type rotating electric machine (IPMSM: Interior Permanent Magnet Synchronous Motor) having a stator in which multiple phases (N phases, where N is any natural number; in this embodiment, a three-phase form with N=3 is illustrated) of coils 7 (stator coils) are arranged in a stator core, and a rotor in which a permanent magnet is arranged in a rotor core. This 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-shaped form in which three-phase coils 7 (U-phase coil 7u, V-phase coil 7v, W-phase coil 7w: see FIG. 3, FIG. 11, etc.) are short-circuited at a neutral point 7N is illustrated. However, the rotating electric machine 70 may have, for example, two sets of three-phase coils 7 and be driven by six-phase AC. 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.

As shown in FIG. 1, the vehicle drive device 9 includes an inverter 5 (see also FIG. 3, FIG. 11, etc.). The inverter 5 is connected to an AC rotating electric machine 70 and a DC power source 3 to convert power between multiple phases of AC and DC. A pair of DC side terminals (DC link terminals T5d) of the inverter 5 are connected to both positive and negative terminals of the DC power source 3. Specifically, the positive terminal (DC link positive terminal T5P) of the pair of DC link terminals T5d is connected to the positive electrode of the DC power source 3, and the negative terminal (DC link negative terminal T5N) of the pair of DC link terminals T5d is connected to the negative electrode of the DC power source 3. In addition, the multiple phase AC side terminals (coil side terminals T5a) of the inverter 5 are connected to each of the multiple phase coils 7. In this embodiment, the inverter 5 includes a U-phase arm, a V-phase arm, and a W-phase arm as multiple phase arms, and the midpoints of each arm are connected to the coil side terminal T5a. 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.

The DC side of the inverter 5 is provided with a smoothing capacitor (DC link capacitor 6) that smoothes the voltage between the positive and negative poles (DC link voltage Vdc). 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 Vdc. When the drive circuit (inverter 5, coil 7, etc.) of the rotating electric machine 70 is used as the on-board charging device 10, the DC link capacitor 6 is disposed between the AC-DC converter 1 and the DC-DC converter 2 described later with reference to Figures 2, 3, 11, etc., and also functions as a smoothing capacitor that smoothes the voltage of the DC power converted by the AC-DC converter 1 (DC link voltage Vdc).

The DC power supply 3 is composed of, for example, a rechargeable secondary battery (battery) such as a lithium ion battery, an electric double layer capacitor, or the like. When the rotating electric machine 70 is the driving force source of the vehicle as in this embodiment, the DC power supply 3 is a high-voltage, large-capacity DC power supply, and the rated power supply voltage is, for example, 200 to 400 V. The DC power supply 3 also includes a current sensor (battery current sensor 31) that detects the input/output current (battery current Ibat: see FIG. 4, etc.) to the DC power supply 3, and a voltage sensor (battery voltage sensor 32) that detects the terminal voltage of the DC power supply 3 (battery voltage Vbat: see FIG. 4, etc.).

Although not shown, for example, when the DC power source 3 is a lithium ion battery, a BMS (Battery Management System) is often provided. A secondary battery such as a lithium ion battery is composed of multiple cells (battery cells). The BMS is a battery management control system that (1) prevents overcharging and overdischarging of cells, (2) prevents overcurrent from flowing through cells, (3) manages the temperature of cells, (4) calculates the state of charge (SOC), and (5) equalizes the cell voltages. The battery current sensor 31 and battery voltage sensor 32 described above may be configured as part of the BMS.

As shown in FIG. 3, the inverter 5 is configured with a plurality of switching elements 5S. For the switching elements 5S, it is preferable to use power semiconductor elements capable of operating at high frequencies, such as IGBTs (Insulated Gate Bipolar Transistors), power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), SiC-MOSFETs (Silicon Carbide - Metal Oxide Semiconductor FETs), SiC-SITs (SiC - Static Induction Transistors), and GaN-MOSFETs (Gallium Nitride - MOSFETs). In this embodiment, an example is shown in which FETs are used as the switching elements 5S. Each switching element 5S is provided with a freewheel diode in parallel, with the forward direction being from the negative pole to the positive pole (from the lower stage to the upper stage).

As shown in FIG. 1, the inverter 5 is controlled by the control device 8. The control device 8 is constructed with a logic circuit such as a microcomputer as its core component. For example, the control device 8 performs current feedback control using a vector control method based on the target torque (torque command) of the rotating electric machine 70 provided as a request signal from another control device such as a vehicle control device 90, which is one of the higher-level control devices, to drive the rotating electric machine 70 via the inverter 5. In the vector control method, the current flowing through the coil 7 of each phase (U-phase current Iu, V-phase current Iv, and W-phase current Iw in this embodiment: see FIG. 3, etc.) is coordinate-converted into vector components of the d-axis, which is the direction of the magnetic field generated by the permanent magnet arranged in the rotor, and the q-axis, which is a direction perpendicular to the d-axis (a direction that advances the magnetic field direction by an electrical angle of π/2), to perform feedback control. The coordinate system to which the coordinates are converted is called the dq-axis orthogonal coordinate system. The operating voltage of logic circuit elements such as a microcomputer is about 3.3 to 5 volts. In this embodiment, for simplicity, the control signal generated by the logic circuit element is transmitted to the inverter 5 via a drive circuit, which is not shown in the figure. Alternatively, the control device 8 may be considered to include the drive circuit.

The actual current flowing through the coils 7 of each phase of the rotating electric machine 70 is detected by a current sensor (motor current sensor 81), and the control device 8 acquires the detection results. In addition, the magnetic pole position (electrical angle) of the rotor of the rotating electric machine 70 at each point in time and the rotation speed (angular velocity) of the rotor are detected by a rotation sensor 82 such as a resolver, and the control device 8 acquires the detection results. The control device 8 executes current feedback control using the detection results of the motor current sensor 81 and the rotation sensor 82. The control device 8 is configured with various functional units for current feedback control, and each functional unit is realized by the cooperation of hardware such as a microcomputer and software (programs).

As described above, the rotating electric machine 70 connected to the DC power source 3 via the inverter 5 functions as an electric motor using 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 using 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. In addition, 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. In addition, even in a hybrid vehicle, it may be more energy efficient to supply power from an external source rather than having the rotating electric machine 70 generate power. 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 installed in the vehicle.

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 a single-phase external AC power source 4. As shown in FIG. 2, the vehicle-mounted charging device 10 includes an AC/DC converter 1 (AC/DC converter) that is connected to the external AC power source 4 and converts the AC power from the external AC power source 4 into DC power, and a DC/DC converter 2 (DC/DC converter) that converts the voltage of the DC converted by the AC/DC converter 1. The AC/DC converter 1 includes a pair of AC side terminals T1a and a pair of DC side terminals T1d, and the AC side terminal T1a of the AC/DC converter 1 is connected to the external AC power source 4. The DC/DC converter 2 includes a pair of first terminals T21 and a pair of second terminals T22, and the pair of first terminals T21 and the pair of DC side terminals T1d of the AC/DC converter 1 are connected, and the pair of second terminals T22 and the positive and negative terminals of the DC power source 3 are connected.

The AC-DC converter 1 and the DC-DC converter 2 are configured with switching elements (switching elements indicated by symbols 1S, 5S, and 15S in FIG. 3 and FIG. 11), and these switching elements are controlled by the control device 8 that drives and controls the rotating electric machine 70 via the inverter 5. Therefore, the control device 8 also controls the AC-DC converter 1 and the DC-DC converter 2. As described later, the vehicle-mounted charging device 10 is also configured with contactors (contactors indicated by symbols 11, 12, and 13 in FIG. 3 and FIG. 11). These contactors are also controlled by the control device 8, or the control device 8 and the vehicle control device 90. As described above with reference to FIG. 1, the control device 8 is included in the drive control system of the rotating electric machine, and the control device 8 is also shared for drive control of the rotating electric machine 70 and charge control of the DC power source 3.

When charging the DC power source 3, power is supplied from the external AC power source 4 to the DC power source 3. Therefore, in terms of circuit configuration, the AC-DC converter 1 arranged relatively closer to the external AC power source 4 (upstream side) may be called a front-end converter or a front converter, and the DC-DC converter 2 arranged relatively closer to the DC power source 3 (downstream side) may be called a back-end converter or a buck converter. In this embodiment, either the AC-DC converter 1 (front converter) or the DC-DC converter 2 (buck converter) is configured using an inverter 5 and a multi-phase coil 7. In addition, as shown in FIG. 2, the AC-DC converter 1 is provided with a grid current sensor 41 and a grid voltage sensor 42 to detect the AC current and the AC voltage.

3 shows a configuration example (first example) of the on-board charging device 10 using the drive control system of the rotating electric machine 70, including the drive circuit of the rotating electric machine 70 (coil 7, inverter 5, etc.), and the circuit block diagram of FIG. 11 shows another configuration example (second example) of the on-board charging device 10 using the drive control system of the rotating electric machine 70, including the drive circuit of the rotating electric machine 70. In the first example shown in FIG. 3, the AC-DC converter 1, which is a front converter connected to the external AC power source 4, is configured by a circuit formed separately from the vehicle drive device 9, and the DC-DC converter 2, which is a back converter connected to the DC power source 3, is configured by sharing the drive circuit of the rotating electric machine 70 (coil 7 and inverter 5). In the second example shown in FIG. 11, the AC-DC converter 1, which is a front converter connected to an external AC power source 4, is configured to share the drive circuit (coil 7 and inverter 5) of the rotating electric machine 70, and the DC-DC converter 2, which is a back converter connected to the DC power source 3, is configured by a circuit formed separately from the vehicle drive device 9.

As shown in Figures 3 and 11, 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 this phase difference reduces the power factor. By controlling the switching element 1S, for example, the current phase can be adjusted, the phase difference can be 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 the DC power converted from the AC power supplied from the external AC power source 4.

In both the first and second examples, the AC-DC converter 1 is configured to include an inductor L1 and a full bridge circuit using a switching element 1S. As shown in FIG. 11, the second example is configured to have four arms, but the second example also has an equivalent full bridge circuit, which will be described in detail later. The AC-DC converter 1, which also has a power factor correction function, is provided with an inductor L1, so that the inductance required to realize the power factor correction function can be appropriately set by the inductor L1. In addition, by providing a full bridge circuit, the AC-DC converter 1 can function as a bidirectional converter capable of AC-DC conversion and DC-AC conversion. For example, the on-board charging device 10 can be used as a device having two functions: a function for charging the DC power source 3 with power supplied from the external AC power source 4, and a function for supplying AC power to a device outside the vehicle with power stored in the DC power source 3.

In recent years, it has been proposed to use the DC power source 3 of an electric vehicle or hybrid vehicle as an emergency power source in the event of a disaster. By equipping the AC-DC converter 1 with a full bridge circuit, the DC power source 3 can be used as such an emergency power source. Of course, in cases where the use of such a DC power source 3 is not considered, the AC-DC converter 1 may be configured as a unidirectional converter that performs only AC-DC conversion. In this case, the AC-DC converter 1 may be configured to have, for example, a half bridge circuit.

As described above with reference to FIG. 2, the first terminal T21 of the DC-DC converter 2 is connected to the DC side terminal T1d of the AC-DC converter 1, and the second terminal T22 is connected to the DC power source 3. In the first example illustrated in FIG. 3, the DC link terminal T5d, which is the DC side terminal of the inverter 5, is the first terminal T21, and the neutral point 7N is the second terminal T22.

As shown in FIG. 3, the vehicle-mounted charging device 10 includes a front-end contactor 11 that selectively connects the AC side terminal T1a of the AC-DC converter 1 to the external AC power source 4 (connects and disconnects the AC side terminal T1a to the external AC power source 4). The front-end contactor 11 includes a contact (front-end contactor first contact 11a) that is connected to the external AC power source 4 and a contact (front-end contactor second contact 11b) that is connected to the AC-DC converter 1. When the front-end contactor first contact 11a and the front-end contactor second contact 11b are connected, the front-end contactor 11 is in a conductive state, and the external AC power source 4 and the vehicle-mounted charging device 10 (AC-DC converter 1) are electrically connected.

As shown in FIG. 3, the vehicle-mounted charging device 10 of the first example includes a battery contactor 12 that selectively connects the DC link terminal T5d, which is the DC side terminal of the inverter 5, and the neutral point 7N to the DC power source 3. In this embodiment, the battery contactor 12 selectively connects the DC link positive terminal T5P and the neutral point 7N to the positive pole of the DC power source 3. The battery contactor 12 includes a battery contactor first contact 12a connected to the positive pole of the DC power source 3, a battery contactor second contact 12b connected to the neutral point 7N, and a battery contactor third contact 12c connected to the DC link positive terminal T5P. When the battery contactor first contact 12a and the battery contactor second contact 12b are connected, the neutral point 7N is connected to the DC power source 3 via the battery contactor 12. The battery contactor third contact 12c is open. When the inverter 5 functions as an on-board charging device 10, the battery contactor 12 is connected in this manner.

When the inverter 5 is used to drive and control the rotating electric machine 70, the battery contactor first contact 12a and the battery contactor third contact 12c are connected, and the DC link positive terminal T5P of the inverter 5 is connected to the DC power source 3 via the battery contactor 12. The battery contactor second contact 12b is open. When the vehicle is parked or when it is necessary to cut off the power supply to the rotating electric machine 70 due to an abnormality or the like, neither the battery contactor second contact 12b nor the battery contactor third contact 12c can be connected to the battery contactor first contact 12a.

In this way, by simply changing the connection form of the battery contactor 12 to the DC power source 3, a circuit can be realized that can switch between the function of driving and controlling the rotating electric machine 70 and the function of charging the DC power source 3 with the external AC power source 4. In other words, the on-board charging device 10 can be configured with a simple configuration.

The front-end contactor 11, the battery contactor 12, and the back-end contactor 13, which will be described later with reference to FIG. 11, are controlled to open and close by the control device 8. Alternatively, these contactors may be controlled by the vehicle control device 90. For example, these contactors can be configured using mechanical relays. Mechanical relays have high insulation when the contacts are open, and it is easy to ensure a large current that can flow when the contacts are closed. However, these contactors are not limited to mechanical relays, and may be configured using semiconductors such as solid-state relays.

As a control method for charging the DC power source 3 with power supplied from the external AC power source 4 while suppressing overcharging (overvoltage) of the DC power source 3 using such an in-vehicle charging device 10, a constant current constant voltage charging control as illustrated in FIG. 5 is known. In the constant current constant voltage charging control, when the state of charge (SOC) of the DC power source 3 is low, the DC power source is charged by constant current charging control that supplies a constant current to the DC power source 3. A constant current (battery current Ibat) flows through the DC power source 3. In FIG. 5, the first phase PH1 corresponds to the period during which the constant current charging control is executed. As charging by the constant current charging control progresses, the value of the SOC increases, and the terminal voltage (battery voltage Vbat) of the DC power source 3 also increases from the voltage at the start of charging (charging start voltage Vbat_e).

When the SOC rises to a predetermined value (e.g., 80 to 90%), or when the battery voltage Vbat rises to a predetermined value (switching voltage Vbat_s), the control method is switched from constant current charging control to constant voltage charging control. In FIG. 5, the second phase PH2 corresponds to the period during which the constant voltage charging control is executed. In the constant voltage charging control, charging is continued while keeping the voltage applied to the DC power source 3 constant. Since the voltage applied to the DC power source 3 is kept constant, the battery current Ibat gradually decreases. The battery voltage Vbat increases at a slower rate. When the battery voltage Vbat rises to a predetermined value (e.g., full charge voltage Vbat_f), or when the battery current Ibat decreases to a predetermined value, or when the SOC rises to a predetermined value (e.g., 98 to 100%), the constant voltage charging control ends, and the charging control also ends.

As described above, in this embodiment, the DC power source 3 is charged using the on-board charging device 10 that utilizes the drive circuit (coil 7, inverter 5, etc.) of the rotating electric machine 70. As shown in Figures 2, 3, 11, etc., the DC link capacitor 6 is disposed between the AC-DC converter 1 and the DC-DC converter 2. In general, the DC link voltage Vdc corresponding to the terminal voltage of the DC link capacitor 6 is maintained at a constant voltage value throughout the entire period of the constant current constant voltage charging control as shown in Figure 5. As described above, the battery voltage Vbat is a low value (Vbat_e) at the start of charging control when the SOC is low, and increases as the constant current charging control progresses. Therefore, at the start of charging control, the voltage difference between the DC link voltage Vdc and the battery voltage Vbat is large, and losses such as switching losses in the on-board charging device 10 (particularly the DC-DC converter 2 in this case) tend to be large. In addition, in the constant current charging control, the battery voltage Vbat increases as the control progresses. Because the battery current Ibat is constant, as shown in FIG. 5, the battery power Pbat is small at the beginning of the charging control (constant current charging control) and increases as the constant current charging control progresses. In other words, the DC power source 3 is not charged with the maximum allowable charging power, so the charging time tends to be long.

In view of this, the present embodiment realizes an in-vehicle charging device 10 that can charge with higher efficiency than conventional constant current constant voltage charging control. As shown in FIG. 4, the control device 8 executes constant power charging control as charging control so that the current (battery current Ibat) flowing through the DC power source 3 and the charging power (battery power Pbat) based on the terminal voltage (battery voltage Vbat) of the DC power source 3 are constant until the terminal voltage (battery voltage Vbat) of the DC power source 3 reaches the switching voltage Vbat_s from a state (for example, charging start voltage Vbat_e) lower than the switching voltage Vbat_s (first phase PH1). In addition, in the constant power charging control, the control device 8 executes variable DC voltage control so that the 6-terminal voltage (DC link voltage Vdc) of the DC link capacitor increases in response to an increase in the terminal voltage (battery voltage Vbat) of the DC power source 3.

Furthermore, as charging control, the control device 8 executes variable power charging control in which the battery power Pbat is gradually reduced so that the battery power Pbat decreases as the battery voltage Vbat increases after the battery voltage Vbat reaches the switching voltage Vbat_s until the full charge voltage Vbat_f is reached, or until the battery current Ibat decreases to a predetermined value, or until the SOC increases to a predetermined value (e.g., 98 to 100%). Preferably, in the variable power charging control, the control device 8 reduces the battery power Pbat until it becomes zero, or reduces the battery current Ibat until it becomes zero.

Note that the full charge voltage Vbat_f, which is the terminal voltage (battery voltage Vbat) of the DC power supply 3 when the DC power supply 3 is in a fully charged state, corresponds to the "first voltage", and the switching voltage Vbat_s corresponds to the "second voltage" which is a preset voltage lower than the "first voltage". In addition, the charging start voltage Vbat_e, which is lower than the "second voltage" and is the battery voltage Vbat when charging starts, can also be called the "third voltage". The full charge voltage Vbat_f and the switching voltage Vbat_s are voltage values that are predefined according to the specifications of the DC power supply 3. On the other hand, the charging start voltage Vbat_e is an arbitrary value when charging is performed, a variable value, and is not a predefined voltage value.

If charging control is continued while keeping the charging power (battery power Pbat) constant, charging will continue with the same power even when the terminal voltage (battery voltage Vbat) of the DC power supply 3 approaches the first voltage (fully charged voltage Vbat_f), and current will continue to be supplied to the DC power supply 3, which may lead to overcharging. By executing variable power charging control after the terminal voltage of the DC power supply 3 reaches the second voltage (switching voltage Vbat_s), it is easy to suppress such overcharging.

In addition, the control device 8 may execute the constant voltage charging control as described above with reference to FIG. 5 as the charging control, instead of the variable power charging control, until the battery voltage Vbat reaches the switching voltage Vbat_s and then reaches the full charge voltage Vbat_f, or until the battery current Ibat decreases to a predetermined value, or until the SOC increases to a predetermined value (e.g., 98 to 100%).

As shown in FIG. 4, in the charging control of this embodiment, when the state of charge (SOC) of the DC power source 3 is low, constant power charging control is executed so that the battery power Pbat is constant. In FIG. 4, the first phase PH1 corresponds to the period during which the constant power charging control is executed. The battery power Pbat is the product of the battery current Ibat and the battery voltage Vbat. Immediately after the start of the charging control, the battery voltage Vbat is low, so that the DC power source 3 can be charged by passing a battery current Ibat having a larger current value than the battery current Ibat in the constant current charging control. As described above, the battery voltage Vbat increases as the charging progresses, so if the battery power Pbat is constant, the battery current Ibat decreases with the charging control. Also, as described above, when the constant power charging control is executed, variable DC voltage control is also executed so that the DC link voltage Vdc increases in parallel with the increase in the battery voltage Vbat. The DC link voltage Vdc is controlled to be parallel to the battery voltage Vbat and to be a voltage that is approximately a constant differential voltage higher than the battery voltage Vbat.

When the SOC rises to a predetermined value (e.g., 80-90%), or when the battery voltage Vbat rises to a predetermined value (switching voltage Vbat_s), the control method is switched from constant power charging control to variable power charging control. In FIG. 4, the second phase PH2 corresponds to the period during which variable power charging control is executed. In variable power charging control, variable DC voltage control is not executed, and the DC link voltage Vdc is maintained at an almost constant voltage. Therefore, in variable power charging control, charging continues while the voltage applied to the DC power source 3 is kept roughly constant. The battery voltage Vbat rises at a slower rate of increase. The battery current Ibat decreases at a higher rate of change than the battery voltage Vbat, and the battery power Pbat also decreases. When the battery voltage Vbat rises to a predetermined value (e.g., the full charge voltage Vbat_f), or when the battery current Ibat falls to a predetermined value (zero or close to zero), or when the battery power Pbat falls to a predetermined value (zero or close to zero), or when the SOC rises to a predetermined value (e.g., 98-100%), the variable power charging control ends, and the charging control also ends.

The following describes the control modes in the control device 8 for realizing constant power charging control, variable power charging control, and variable DC voltage control. Figure 6 shows a schematic control block diagram of the front-end control unit 810 that controls the AC-DC converter 1 (front converter), and Figure 7 shows a schematic control block diagram of the back-end control unit 820 that controls the DC-DC converter 2 (buck converter).

In FIG. 6, the "grid voltage Vgrid" is an AC voltage input from the external AC power supply 4, indicated by "Vsinωt". Here, "ω" is angular velocity, and "t" is time. In this example, the control device 8 performs sine wave control, not vector control in the dp-axis vector coordinate system. In the case of vector control, the grid voltage Vgrid is indicated by "Vcosωt". Furthermore, the "grid current Igrid" is an AC current input from the external AC power supply 4. "V ^* dc" is a command value of the DC link voltage Vdc. In the variable DC voltage control described above, the value of the DC link voltage Vdc is variably controlled. As is clear from FIG. 3, the DC link voltage Vdc is a voltage output from the AC-DC converter 1, and therefore the AC-DC converter 1 is controlled by the control device 8 based on the DC link voltage command V ^* dc.

As shown in FIG. 6, the front-end control unit 810 includes a grid current command calculation unit 815, a front-end feedback calculation unit 811, a front-end feedforward calculation unit 812, a front-end pulse generation unit 813, and a grid voltage detection unit 819. The front-end control unit 810 performs calculations using information detected by the grid current sensor 41, the grid voltage sensor 42, the DC link voltage sensor 61, etc. described above.

The grid voltage detection unit 819 detects the peak voltage (grid voltage peak value Vgrid_pk), angular velocity ω, and waveform "sinωt" from the grid voltage Vgrid for use in the subsequent control block. In this embodiment, the grid voltage detection unit 819 is configured using a phase locked loop (PLL). As described above, in the case of vector control, "cosωt" is detected as the waveform.

The grid current command calculation unit 815 performs proportional-integral control (PI control) based on the deviation between the DC link voltage Vdc and the DC link voltage command V ^* dc to calculate a power value, and calculates a grid current command I ^* grid based on the power value and the grid voltage Vgrid. As shown in Fig. 6, the grid current command I*grid is calculated by multiplying the value obtained by dividing the grid voltage Vgrid by the square of the effective value of ^the grid voltage Vgrid (grid voltage effective value Vgrid_rms) and the calculation result of the PI control based on the deviation of the DC link voltage Vdc.

The front-end feedback calculation unit 811 performs proportional-integral control (PI control) based on the deviation between the grid current Igrid and the grid current command I ^* grid to calculate a front-end feedback voltage command Vfe_fb0. The front-end feedback calculation unit 811 also calculates a front-end feedback duty Vfe_fb by dividing the front-end feedback voltage command Vfe_fb0 by the DC link voltage Vdc.

The front-end feedforward calculation unit 812 calculates the front-end feedforward duty Vfe_ff. Here, in order to generate a sinusoidal voltage command, the wave size (amplitude or peak value) and phase are calculated. The size of the voltage command is defined by the ratio between the input voltage and the output voltage (input voltage Vin/output voltage Vout), and is calculated by dividing the grid voltage peak value Vgrid_pk by the DC link voltage command V ^* dc. The phase is determined in consideration of three elements: the phase "ωt" of the grid voltage Vgrid, the phase delay due to the inductor L1 (denoted as "θ1"), and the phase delay associated with the delay of the grid current control (denoted as "θ2"). Note that the delay of the grid current control corresponds to the delay time associated with the grid current command I ^* grid being calculated in one control cycle of the control device 8 after the grid current Igrid is detected, and the AC-DC converter 1 being controlled by the voltage command calculated in the next control cycle.

The phase delay "θ1" caused by the inductor L1 is expressed by the following formula, where the inductance of the inductor L1 is "L." Here, "I ^* grid_pk" is the grid current command peak value.

θ1=-I ^* grid_pk・(ωL/Vgrid_pk)

The phase delay "θ2" associated with the delay in grid current control is calculated as follows, as a phase equivalent to 1.5 cycles, since a delay of one control cycle occurs in the calculation of the voltage command. By performing a correction for 1.5 cycles, it is possible to correct the average voltage over the entire carrier cycle one cycle ahead, in which the control calculation results are reflected.

θ2 = ω (1.5 cycles of grid current control/1 [s])

Based on this, the sinusoidal front-end feedforward voltage command Vfe_ff0 is defined as follows:

Vfe_ff0=1-(Vgrid_pk/V ^* dc)sin(ωt-θ1+θ2)

Since a normal sine wave has positive and negative values with zero as the center of amplitude, known conversion processes such as shift processing are performed to generate pulses with positive digital values. In the above calculation example, the front-end feedforward voltage command Vfe_ff0 is calculated in an offset state so that there are no negative values, so it is only necessary to adjust the amplitude. The "1/2" controller in the front-end feedforward calculation unit 812 in FIG. 6 is an amplitude adjuster, and the front-end feedforward duty Vfe_ff is generated through this amplitude adjuster.

Vfe_ff=Vfe_ff0/2

The front-end pulse generating unit 813 generates a pulse (pulse for pulse width modulation) that controls the switching of the switching element 1S that constitutes the AC-DC converter 1 based on the final duty (front-end duty Vfe) obtained by adding the front-end feedback duty Vfe_fb and the front-end feedforward duty Vfe_ff. The front-end duty Vfe is calculated as follows.

Vfe=Vfe_fb+Vfe_ff

This front-end duty Vfe corresponds to the duty in pulse width modulation control. The final switching pulse is generated by a known calculation based on the carrier wave (front-end carrier CA_fe) and the front-end duty Vfe, so a detailed explanation is omitted.

Note that, for ease of understanding, the sinusoidal wave control has been described as an example. However, it is also possible to configure the front-end control unit 810 so that the calculations are performed in the dq axis vector coordinate system. Those skilled in the art will be able to easily substitute this from the control block diagram in FIG. 6, so a detailed description will be omitted here.

In Fig. 7, "Ia" indicates the "coil current" which is the sum of currents flowing through the coils 7 of multiple phases. In this embodiment, a three-phase coil 7 is provided, and in the configuration illustrated in Fig. 3, the coil current Ia is the sum of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw. "P ^* bat" is the command value (battery power command) of the battery power Pbat in constant power charging control. "V ^* bat" is the command value (battery voltage command) of the battery voltage Vbat.

As shown in FIG. 7, the back-end control unit 820 includes a back-end feedback calculation unit 821, a back-end feedforward calculation unit 822, and a back-end pulse generation unit 823. The back-end control unit 820 performs calculations using information detected by the motor current sensor 81, the battery current sensor 31, the battery voltage sensor 32, the DC link voltage sensor 61, and the like. The battery power Pbat can be calculated by multiplying the battery current Ibat and the battery voltage Vbat.

The back-end feedback calculation unit 821 calculates a back-end feedback voltage command Vbe_fb0 by performing proportional-integral control (PI control) based on the deviation between a battery current command (I ^* bat) obtained by dividing the battery power command P ^* bat by the battery voltage Vbat and a coil current Ia corresponding to the current (battery current Ibat) flowing through the DC power supply 3. The back-end feedback calculation unit 821 also calculates a back-end feedback duty Vbe_fb by dividing the back-end feedback voltage command Vbe_fb0 by the DC link voltage Vdc.

The back-end feedforward calculation unit 822 calculates a back-end feedforward duty Vbe_ff. The back-end feedforward duty Vbe_ff is defined as a ratio between an input voltage and an output voltage (input voltage Vin/output voltage Vout), and the back-end feedforward calculation unit 822 calculates the back-end feedforward duty Vbe_ff by dividing the battery voltage command V ^* bat by the DC link voltage Vdc.

The back-end pulse generating unit 823 generates a pulse (pulse for pulse width modulation) that controls the switching of the switching element 5S of the inverter 5, which is a switching element that constitutes the DC-DC converter 2, based on the back-end duty Vbe, which is the sum of the back-end feedback duty Vbe_fb and the back-end feedforward duty Vbe_ff. The back-end duty Vbe corresponds to the duty in pulse width modulation control. The final switching pulse is generated by a known calculation based on the carrier wave (back-end carrier CA_be) and the back-end duty Vbe, so a detailed description is omitted.

As shown in FIG. 3, when the DC-DC converter 2 is configured using the inverter 5, there are six switching elements 5S to be controlled. However, as described above, since the neutral point 7N of the coil 7 is connected to the positive pole of the DC power supply 3, the three-phase arms of the inverter 5 can be considered as one arm. Therefore, the upper-stage switching elements 5S of each phase can be controlled with the same switching pulse, and the lower-stage switching elements 5S can be controlled with the same switching pulse.

As described above with reference to FIG. 3, the vehicle-mounted charging device 10 includes a front-end contactor 11 that selectively connects the AC side terminal T1a of the AC-DC converter 1 to the external AC power source 4 (connects and disconnects the AC side terminal T1a to the external AC power source 4). The vehicle-mounted charging device 10 includes a battery contactor 12 that selectively connects the DC link terminal T5d, which is the DC side terminal of the inverter 5, to the DC power source 3 and the neutral point 7N. When performing charging control, the control device 8 closes the front-end contactor 11 and controls the battery contactor 12 so that the battery contactor first contact 12a and the battery contactor second contact 12b are connected. At this time, for example, when the vehicle has been stopped for a long time, the DC link capacitor 6 is discharged and the DC link voltage Vdc is almost zero. When charging control is started, a large current flows in transiently to charge the DC link capacitor 6. In the configuration shown in FIG. 3, the AC-DC converter 1 is used only for charging, so the switching element 1S that constitutes the AC-DC converter 1 is not required to have the performance to tolerate a large current that drives the rotating electric machine 70. In other words, it is not desirable for the transient current for charging the DC link capacitor 6 to flow through such an element that does not have a high current resistance.

For this reason, in this embodiment, the control device 8 executes pre-charge control to charge the DC link capacitor 6 before executing the charging control.

The charge stored in the smoothing capacitor (here, DC link capacitor 6) gradually decreases due to discharging after the electrical connection between the charge source and the smoothing capacitor is cut off. When charging control is started from a state in which the smoothing capacitor is almost completely discharged, the smoothing capacitor is rapidly charged. In other words, when charging control starts, a large transient current flows through the path from the charge source to the smoothing capacitor. Since the steady current flowing through the path during charging control is much smaller than such a transient current, measures such as increasing the allowable value of the current that can flow through the path in preparation for such a transient current are required, which may lead to an increase in the size of the device. When pre-charge control is executed to charge the smoothing capacitor prior to charging control, it is possible to suppress the flow of a large transient current accompanying the start of charging control, and it is easy to configure the vehicle-mounted charging device 10 simply.

As described above, the control device 8 executes pre-charge control to charge the DC link capacitor 6 before executing the charging control. At this time, it is preferable that the control device 8 executes pre-charge control so that charge is supplied to the DC link capacitor 6 via a path different from the path that supplies charge to the DC link capacitor 6 when the charging control is executed.

As described above, the vehicle-mounted charging device 10 includes a battery contactor 12 that selectively connects the DC link terminal T5d, which is the DC side terminal of the inverter 5, to the DC power source 3 and the second terminal T22 of the DC-DC converter 2. In pre-charge control, the control device 8 controls the battery contactor 12 so that the DC power source 3 and the DC link terminal T5d are connected, and in charge control, the control device 8 controls the battery contactor 12 so that the DC power source 3 and the second terminal T22 of the DC-DC converter 2 are connected. During execution of pre-charge control, the front-end contactor 11 is controlled to an open state.

As shown in FIG. 8, in precharge control, when the battery contactor 12 is controlled so that the DC power source 3 and the DC link terminal T5d are connected, the DC power source 3 and the DC link capacitor 6 are directly connected, and the DC link capacitor 6 is charged by the DC power source 3. Since no switching elements or other elements are interposed in this path, the DC link capacitor 6 can be safely and quickly charged. Although the SOC of the DC power source 3 is low enough that charging control is required, there is often still enough charge remaining to charge the DC link capacitor 6. Therefore, the DC link capacitor 6 can be appropriately charged.

The smoothing capacitor (here, DC link capacitor 6) is disposed between AC-DC converter 1 and DC-DC converter 2, and is connected between the positive and negative poles of the DC side terminal (DC link terminal T5d) of inverter 5. By connecting the DC power source 3 to the DC side terminal of inverter 5 by a contactor (battery contactor 12), charge can be supplied directly from the DC power source 3 to the smoothing capacitor during precharge control. Since no components that require consideration of the amount of current that can be passed, such as switching elements, are disposed in the path from the DC power source 3 to the smoothing capacitor, the smoothing capacitor can be safely and quickly charged with a simple configuration.

Here, an example of a start sequence, which is a sequence at the start of integrated charging control including precharge control, will be described. Integrated charging control is a control that combines precharge control and charging control. Before the start of integrated charging control, the battery contactor 12, the front-end contactor 11, all switching elements 1S of the AC-DC converter 1, and all switching elements 2S of the DC-DC converter 2 are in the off state. When the control device 8 starts integrated charging control, it first controls the battery contactor first contact 12a and the battery contactor third contact 12c of the battery contactor 12 to be closed. As a result, as shown in FIG. 8, the DC link capacitor 6 is charged by the DC power source 3. When the SOC of the DC power source 3 is low, the DC link voltage Vdc rises to a voltage lower than the battery voltage Vbat at the time of full charge. The control device 8 can determine the end of precharge control, for example, based on the detection result of the DC link voltage sensor 61, when the DC link voltage Vdc reaches the battery voltage Vbat and the voltage no longer rises.

Next, the control device 8 starts charging control. Specifically, the control device 8 controls the front-end contactor 11 and the battery contactor 12 to connect the front-end contactor first contact 11a and the front-end contactor second contact 11b, and to connect the battery contactor first contact 12a and the battery contactor second contact 12b. The control device 8 may control the front-end contactor 11 and the battery contactor 12 at the same timing, or in sequence. When the control device 8 controls in sequence, either contactor may be controlled first. Incidentally, the battery contactor 12 has the battery contactor second contact 12b and the battery contactor third contact 12c exclusively connected to the battery contactor first contact 12a. Therefore, when the control device 8 connects the first battery contactor contact 12a and the second battery contactor contact 12b following the pre-charge control, the control device 8 opens the connection between the first battery contactor contact 12a and the third battery contactor contact 12c and connects the first battery contactor contact 12a and the second battery contactor contact 12b. Also, as described above, the control device 8 may determine the end of the pre-charge control when the DC link voltage Vdc reaches the battery voltage Vbat and the voltage no longer increases, and may open the connection between the first battery contactor contact 12a and the third battery contactor contact 12c in advance, and control all the contacts of the battery contactor 12 to be in an open state.

The control device 8 connects the front-end contactor first contact 11a and the front-end contactor second contact 11b, connects the battery contactor first contact 12a and the battery contactor second contact 12b, and then starts switching control of the AC-DC converter 1. The DC link voltage Vdc rises from the battery voltage Vbat to the target voltage of the DC link voltage Vdc in the charging control due to the power supplied from the external AC power source 4 via the AC-DC converter 1. When the control device 8 determines that the DC link voltage Vdc has reached the target voltage based on the detection result of the DC link voltage sensor 61, it starts switching control of the DC-DC converter 2.

Figures 9 and 10 show, as a comparative example, a case in which the DC link capacitor 6 is charged through a path different from that in Figure 8. In the example of Figure 9, the front-end contactor 11 is closed, and both contacts of the battery contactor 12 are open. In this case, the freewheel diode provided in the switching element 1S of the AC-DC converter 1 causes the AC-DC converter 1 to function as a diode full-wave rectifier circuit. As a result, a transient charging current flows from the external AC power source 4 through the switching element 1S (freewheel diode) to the DC link capacitor 6.

Since the AC-DC converter 1 is used only for charging the DC power source 3, it is configured with switching elements that can pass a smaller current value than the inverter 5 that drives the rotating electric machine 70. For this reason, it is not preferable for such a current to flow even transiently. However, although the cost of parts increases, configuring the AC-DC converter 1 using switching elements that can pass a larger current value does not prevent the formation of a path such as that shown in FIG. 9 and the precharge control. In addition, if the AC-DC converter 1 is configured to allow charging of the DC link capacitor 6 through the path shown in FIG. 9, the control device 8 may perform charging control without performing precharge control.

10, the front-end contactor 11 is opened, and the battery contactor 12 is connected to the battery contactor first contact 12a and the battery contactor second contact 12b in the same manner as when charging control is executed. In this case, a transient charging current flows to the DC link capacitor 6 through a freewheel diode provided in the switching element 5S of the inverter 5 constituting the DC-DC converter 2. The switching element 5S of the inverter 5 drives the rotating electric machine 70, so the value of the current that can be passed is large. Therefore, from the viewpoint of the magnitude of the current, it is considered possible to charge the DC link capacitor 6 through this path. However, according to a simulation by the inventors, it was observed that the coil current Ia and the DC link voltage Vdc fluctuate greatly and the peak value becomes high at the start of the precharge control. Therefore, compared to the precharge control via the DC-DC converter 2 as shown in FIG. 10, the precharge control by directly connecting the DC power source 3 and the DC link capacitor 6 without passing through the DC-DC converter 2 as shown in FIG. 8 is preferable.

The above-mentioned charging control (constant power charging control, variable power charging control, variable DC voltage control, precharge control) can be implemented not only by the first example of the on-board charging device 10 having the circuit configuration described above with reference to FIG. 3, but also by the second example of the on-board charging device 10 having the circuit configuration shown in FIG. 11.

In the second example of the on-board charging device 10 shown in FIG. 11, the AC-DC converter 1 shares the drive circuit (inverter 5, coil 7) of the rotating electric machine 70. This AC-DC converter 1 is configured with an inverter 5, a multi-phase coil 7, a single-phase arm 15 connected in parallel to the inverter 5, and an inductor L1. Between the neutral point 7N of the multi-phase coil 7 and the midpoint of the single-phase arm 15, the inductor L1 and the external AC power source 4 are connected in series. The three-phase arms constituting the inverter 5 are connected in parallel to form a single arm, and together with the single-phase arm 15, they form a full bridge circuit. The switching element 5S constituting the inverter 5 and the switching element 15S of the single-phase arm 15 are elements with the same electrical specifications. The inductor L1 is indicated by the same reference numeral as in the first example shown in FIG. 3 because it is connected to the external AC power source 4 in the same arrangement, and does not mean that the circuit constants are the same.

The DC-DC converter 2 of the vehicle-mounted charging device 10 of the second example is formed independently without sharing the drive circuit of the rotating electric machine 70. This DC-DC converter 2 is configured as a step-down DC-DC conversion circuit, including an arm in which switching elements are connected in series so as to be switched complementarily, a back-end inductor L2 connected to the midpoint of the arm, and an output smoothing capacitor C2 connected in parallel to the DC power source 3. The DC-DC converter 2 may be configured as a step-up converter or a step-up/step-down converter.

The vehicle-mounted charging device 10 of the second example includes a front-end contactor 11 and a battery contactor 12 similar to those of the vehicle-mounted charging device 10 of the first example. The connection form and opening/closing control are similar to those of the vehicle-mounted charging device 10 of the first example, so a description thereof will be omitted. The vehicle-mounted charging device 10 of the second example also includes a back-end contactor 13 that selectively connects the AC-DC converter 1 (inverter 5) to the DC power source 3, or connects the AC-DC converter 1 (inverter 5) to the DC-DC converter 2. The back-end contactor 13 includes a back-end contactor first contact 13a connected to the positive electrode of the AC-DC converter 1 (inverter 5), a back-end contactor second contact 13b connected to the positive electrode of the input side of the DC-DC converter 2, and a back-end contactor third contact 13c connected to the battery contactor third contact 12c and selectively connected to the positive electrode of the DC power source 3. When the back-end contactor first contact 13a and the back-end contactor second contact 13b are connected, the AC-DC converter 1 (inverter 5) and the DC-DC converter 2 are connected.

When the inverter 5 is used to drive and control the rotating electric machine 70, the battery contactor first contact 12a and the battery contactor third contact 12c are connected as described above with reference to FIG. 3. In this state, when the back-end contactor first contact 13a and the back-end contactor third contact 13c are connected, the inverter 5 and the DC power source 3 are connected via the back-end contactor 13 and the battery contactor 12.

When a single-phase external AC power supply 4 is connected to the neutral point 7N, as in this vehicle-mounted charging device 10, the same current flows through the three-phase coils 7. As a result, due to magnetic saturation, etc., the inductance in the coils 7 becomes smaller, and it is considered that the harmonic current of the system current of the external AC power supply 4 and the peak value of the ripple current after DC conversion become larger. For this reason, in the vehicle-mounted charging device 10 of the second example, an inductor L1 is added between the external AC power supply 4 and the neutral point 7N of the multi-phase coils 7 to ensure the necessary inductance.

In this second example of the on-board charging device 10, the AC-DC converter 1 and the DC-DC converter 2 are also controlled by the control mode described above with reference to Figures 6 and 7. Since the circuit configurations are different, there are differences, but since a person skilled in the art would be able to make appropriate substitutions, detailed explanations will be omitted.

1: AC-DC converter, 2: DC-DC converter, 3: DC power source, 4: External AC power source, 5: Inverter, 6: DC link capacitor (smoothing capacitor), 7: Coil, 7N: Neutral point, 8: Control device, 9: Vehicle drive device, 10: Vehicle charging device, 12: Battery contactor (contactor), 70: Rotating electric machine, Pbat: Battery power (charging power), T1a: AC side terminal, T1d: DC side terminal, T21: First terminal, T22: Second terminal, T5d: DC link terminal (DC side terminal of inverter), Vbat: Battery voltage (terminal voltage of DC power source), Vbat_f: Full charge voltage (first voltage), Vbat_s: Switching voltage (second voltage), Vdc: DC link voltage (terminal voltage of smoothing capacitor)

Claims (5)

An on-board charging device for a vehicle includes 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 DC and multiple phase AC, and a DC power supply connected to the inverter, the on-board charging device charging the DC power supply with power supplied from a single-phase external AC power supply,
an AC-DC converter that converts AC power from the external AC power source into DC power;
a DC/DC converter that converts the voltage of the DC power converted by the AC/DC converter;
a smoothing capacitor disposed between the AC-DC converter and the DC-DC converter, smoothing a voltage of the DC power converted by the AC-DC converter;
a control device for controlling the AC-DC converter and the DC-DC converter,
one of the AC-DC converter and the DC-DC converter is configured using the inverter and the coils of a plurality of phases,
an AC side terminal of the AC-DC converter is connected to the external AC power supply;
a DC side terminal of the AC-DC converter is connected to a first terminal of the DC-DC converter;
a second terminal of the DC-DC converter different from the first terminal is connected to the DC power source;
The control device includes:
A terminal voltage of the DC power supply when the DC power supply is in a fully charged state is defined as a first voltage, and a voltage that is lower than the first voltage and set in advance as a second voltage,
a constant power charging control is executed as a charging control until a terminal voltage of the DC power supply reaches the second voltage from a state lower than the second voltage, so that a charging power based on a current flowing through the DC power supply and the terminal voltage of the DC power supply is constant;
In the constant power charging control, variable DC voltage control is executed so that the terminal voltage of the smoothing capacitor increases in response to an increase in the terminal voltage of the DC power supply. The vehicle-mounted charging device according to claim 1, wherein the control device executes variable power charging control as the charging control, in which the charging power is gradually reduced so that the charging power is reduced as the terminal voltage increases after the terminal voltage reaches the second voltage until the terminal voltage reaches the first voltage. The on-board charging device according to claim 1 or 2, wherein the control device performs a pre-charge control to charge the smoothing capacitor before performing the charging control. a contactor that selectively connects a DC side terminal of the inverter and the second terminal of the DC-DC converter to the DC power source;
The control device includes:
In the precharge control, the contactor is controlled so that the DC power source and a DC side terminal of the inverter are connected to each other;
The in-vehicle charging device according to claim 3 , wherein the charging control comprises controlling the contactor so that the DC power source and the second terminal of the DC-DC converter are connected to each other. a contactor that selectively connects a DC side terminal of the inverter and the second terminal of the DC-DC converter to the DC power source;
the DC-DC converter is configured with the inverter and the coils of a plurality of phases,
a DC side terminal of the inverter is the first terminal,
The vehicle-mounted charging device according to claim 1 , wherein the neutral point is the second terminal.

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