On-vehicle charger

Abstract

To provide an on-vehicle charger that can charge a DC power supply of a vehicle drive device equipped with a rotating electric machine, an inverter, and the DC power supply with high efficiency using power from an external AC power supply by utilizing a coil of the rotating electric machine and the inverter.SOLUTION: An on-vehicle charger includes: a first circuit with an AC-DC converter; a second circuit with an active decoupling circuit; and a control device. The control device executes constant power charging control so that a charging power is constant until a terminal voltage of a DC power supply reaches a second voltage that is lower than the terminal voltage of the DC power supply in a fully charged state. In the constant power charging control, a grid current Igrid is variably controlled by feedback control based on a deviation between a battery voltage command value V*bat and a battery voltage Vbat and a grid voltage Vgrid, and by feedforward control based on the grid voltage Vgrid, the battery voltage Vbat, and a battery power command Pb*.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] 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 SOC increases, and the terminal voltage (battery voltage) of the DC power source also increases. When the SOC increases to a preset value or when 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 is continued 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. In the constant-current constant-voltage charging control, the DC power supply can be charged in a relatively short time while suppressing overcharging (overvoltage) of the DC power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-201382 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, a vehicle equipped with a rotating electric machine as a driving force source for wheels, such as an electric vehicle or a hybrid vehicle, 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 drive 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 decoupling capacitor that smoothes the DC voltage is arranged between the inverter and the DC power source. When an inverter and a decoupling capacitor are included in the drive circuit of the rotating electric machine used in the on-board charging device, the terminal voltage (DC link voltage) of the decoupling 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. That is, in the conventional constant current constant voltage charging control, the loss in the on-board charging device tends to be large.

[0005] Furthermore, 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 conventional constant current constant voltage control, 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.

[0006] In view 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 that has a rotating electric machine, an inverter, and a DC power supply with high efficiency using power from an external AC power supply by utilizing the coil of the rotating electric machine and the inverter. [Means for solving the problem]

[0007] In view of the above, an on-board charging device is an on-board charging device that charges a DC power source of a vehicle drive device, the on-board charging device having 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 source connected to the inverter, with power supplied from an external AC power source, the on-board charging device comprising: a first circuit having an AC-DC converter that converts power between AC power on the side of the external AC power source and a first DC power; a second circuit that is configured to include the inverter, the multiple-phase coils, and an active filter capacitor, and has an active decoupling circuit that attenuates pulsating components from the first DC power to generate second DC power that charges the DC power source; and a control device that controls the first circuit and the second circuit, wherein a DC side terminal of the first circuit and a DC side terminal of the inverter are connected without passing through any other passive components, and the active filter capacitor is The control device is connected between the neutral point of the coil and a negative pole of a DC power supply, and sets a terminal voltage of the DC power supply when the DC power supply is in a fully charged state as a first voltage, and a preset voltage lower than the first voltage as a second voltage, and executes constant power charging control as charging control until a battery voltage, which is the terminal voltage of the DC power supply, reaches the second voltage from a state lower than the second voltage, so that a battery current, which is a current flowing through the DC power supply, and a charging power based on the battery voltage are constant, and in the constant power charging control, a grid current supplied to the DC power supply from the external AC power supply side is variably controlled by feedback control based on a deviation between a command value of the battery voltage and the battery voltage and a grid voltage, which is a voltage value of AC power supplied from the external AC power supply, and feedforward control based on the grid voltage, the battery voltage, and a battery power command for charging the DC power supply.

[0008] The DC power output from the first circuit including the AC-DC converter is superimposed with pulsating components of harmonics of the frequency of the external AC power source. In order to generate DC power from which the pulsating components have been removed, in many cases, a DC-DC converter is provided following the first circuit, and the DC power source is charged with the DC power converted by the DC-DC converter. In addition, in this case, a decoupling capacitor is often provided between the AC-DC converter and the DC-DC converter. Since a capacitor with a relatively large capacitance is used for this decoupling capacitor, the physical size of the vehicle-mounted charging device tends to be large. In this embodiment, the first circuit including the AC-DC converter and the second circuit including an active decoupling circuit that attenuates the pulsating components are connected without passing through passive components including such a decoupling capacitor. Therefore, it is easy to keep the physical size of the vehicle-mounted charging device small. Furthermore, according to this configuration, the inverter for driving the rotating electric machine and the coil of the rotating electric machine are used as switching elements and inductors that configure the active decoupling circuit, and it is easy to suppress an increase in the overall size of the vehicle-mounted device.

[0009] According to this configuration, when the state of charge (SOC) of the DC power supply is low and the terminal voltage of the DC power supply is less than the second voltage, constant power charging control is executed so that the charging power is constant as charging control until the terminal voltage reaches the second voltage. Therefore, the DC power supply can be charged with the maximum allowable charging power, and the charging time can be shortened. In addition, in the constant power charging control, the grid current supplied from the external AC power supply is variably controlled by feedforward control and feedback control based on the battery voltage, the command value of the battery voltage, the grid voltage, and the battery power command. Therefore, the DC power supply can be efficiently charged with an appropriate current according to the conditions, rather than a uniform current as in the constant current charging control. That is, according to this configuration, it is possible to realize an in-vehicle charging device that can charge the DC power supply of a vehicle drive device including a rotating electric machine, an inverter, and a DC power supply with high efficiency by using the coil of the rotating electric machine and the inverter.

[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 an example of an on-board charging device using a drive control system for a rotating electric machine. [Diagram 3] A functional block diagram that is a variation of the circuit block diagram shown in Figure 2. [Figure 4] Graph showing the concept of constant power charging [Diagram 5] FIG. 13 is a diagram showing the relationship between the battery voltage and the capacitor voltage command. [Figure 6] Control block diagram for the first circuit functioning as an AC-DC converter [Figure 7] Control block diagram for controlling the second circuit that functions as an active decoupling circuit [Figure 8] Diagram showing current flow in an active decoupling circuit (active filter capacitor charging (capacitor current is positive and increasing)) [Figure 9] Diagram showing current flow in an active decoupling circuit (active filter capacitor charging (capacitor current is positive and decreasing)) [Figure 10] Diagram showing the current flow in an active decoupling circuit (active filter capacitor discharging (capacitor current is negative and the absolute value of the capacitor current increases)) [Figure 11] Diagram showing the current flow in an active decoupling circuit (active filter capacitor discharging (capacitor current is negative and the absolute value of the capacitor current is decreasing)) [Figure 12] Waveform diagram showing the relationship between grid voltage, grid current, capacitor current, and capacitor voltage [Figure 13]Waveform diagram showing pulse width modulation when controlling capacitor current [Figure 14] A time chart showing an example of a start sequence [Figure 15] A circuit block diagram showing a comparative example (third charger) of an on-board charger using a drive control system for a rotating electric machine. [Figure 16] A circuit block diagram showing a comparative example (second charging device) of an on-board charging device using a drive control system for a rotating electric machine. [Figure 17] A circuit block diagram showing a comparative example (first charging device) of an on-board charging device using a drive control system for a rotating electric machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the vehicle-mounted charging device will be described with reference to the drawings. The circuit block diagram of FIG. 1 shows a schematic diagram of a drive control system of a rotating electric machine 70, and the circuit block diagram of FIG. 2 shows an 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. In the embodiment shown in FIG. 2, the external AC power source 4 is connected to a first circuit 1, which will be described later, via an EMI filter FLT. The EMI filter FLT can be disposed as appropriate. Also, this does not prevent a configuration in which the vehicle-mounted charging device 10 is configured without including an EMI filter FLT.

[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 in series an upper-stage switching element (fifth switch S5) arranged on the positive side and a lower-stage switching element (sixth switch S6) arranged on the negative side. The midpoint of each arm, i.e., the connection point between the upper-stage switching element and the lower-stage switching element, is connected to the respective coils 7. Specifically, the midpoint of the U-phase arm is connected to U-phase coil 7u, the midpoint of the V-phase arm is connected to V-phase coil 7v, and the midpoint of the W-phase arm is connected to W-phase coil 7w.

[0016] A decoupling capacitor (DC link capacitor 6) that smoothes the voltage (DC link voltage) between the positive and negative poles is provided on the DC side of the inverter 5. In addition, a voltage sensor (DC link voltage sensor 61) that detects the DC link voltage is also provided on the DC side of the inverter 5.

[0017] The DC power source 3 is, for example, a rechargeable secondary battery (battery) such as a lithium ion battery, an electric double layer capacitor, or the like. When the rotating electric machine 70 is the driving force source of the vehicle as in this embodiment, the DC power source 3 is a high-voltage, large-capacity DC power source, and the rated power supply voltage is, for example, 200 to 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. In this embodiment, an example is shown in which a field effect transistor (FET) is used as the switching element. In addition to the FET, an insulated gate bipolar transistor (IGBT) may be used as the switching element. In this embodiment, a freewheel diode is connected in parallel to each switching element 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 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 operation processor 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 microcomputer or the like 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 configure an on-board charging device using the inverter 5 and the coil 7.

[0025] The vehicle-mounted charging device 10 of this embodiment charges the DC power source 3 of the vehicle drive device 9 with power supplied from an external AC power source 4. As shown in FIG. 2, the vehicle-mounted charging device 10 includes a first circuit 1 including an 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 a first DC power, and a second circuit 2 including an active decoupling circuit that attenuates a pulsating component from the first DC power to generate a second DC power for charging the DC power source 3. As will be described in detail later, in this embodiment, the second circuit 2 includes an inverter 5, a multi-phase coil 7, and an active filter capacitor Cs. The DC side terminal of the first circuit 1 and the DC side terminal of the inverter 5 included in the second circuit 2 are connected without passing through any other passive components. The active filter capacitor Cs is connected between the neutral point 7N of the coil 7 and the negative pole of the DC.

[0026] The first circuit 1 and the second circuit 2 are configured to include switching elements, and these switching elements are controlled by a control device 80 that drives and controls the rotating electric machine 70 via the inverter 5. 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 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. The control device 80 is a control device that controls the rotating electric machine, and is also a control device that controls the in-vehicle charging device 10. As will be described later, the in-vehicle charging device 10 is configured to include contactors (main contactor 11, function switching contactor 12, and grid contactor 13). These contactors are also controlled by the control device 80, or by the control device 80 and the vehicle control device 90.

[0027] FIG. 17 shows a first comparative example (first charger 10X) of the in-vehicle charging device 10 of this embodiment. The first charger 10X is also configured with a first circuit 1 and a second circuit 2. The first circuit 1 is configured as an AC-DC converter including a full bridge 1c having a first arm 1a and a second arm 1b, and an input inductor Li connected between the full bridge 1c and an external AC power source 4. The second circuit 2 is configured as a DC-DC converter including a step-down chopper having a single-arm half bridge and a choke coil Le. The first charger 10X is different from the in-vehicle charging device 10 of this embodiment illustrated in FIG. 2 in that the first circuit 1 shares the drive circuit of the rotating electric machine 70. Specifically, the first arm 1a is formed by an inverter 5, and the input inductor Li is formed by a coil 7. The decoupling capacitor arranged between the first circuit 1 and the second circuit 2 shares the DC link capacitor 6 in the drive circuit of the rotating electric machine 70 (see FIG. 1).

[0028] However, the rotating electric machine 70 that serves as the driving force source for the wheels is designed to have a high power density, and the coil 7 may not have sufficient inductance as the input inductor Li of the AC-DC converter. If the inductance of the input inductor Li is small, the peak value of the pulsation of the harmonic current of the system current of the external AC power source 4 tends to be large during AC-DC conversion. One method for suppressing this is to increase the control frequency of the inverter 5 that constitutes the first circuit 1. Alternatively, in order to reduce the pulsation on the side of the second circuit 2, it is possible to increase the control frequency of the DC-DC converter. However, when the control frequency is increased, it is necessary to shorten the control period (operation frequency) of the control device 80 that controls the inverter 5 and the DC-DC converter. For this purpose, it becomes necessary to use a microcomputer or the like capable of high-speed operation as the control device 80, which leads to an increase in the cost of the on-board charging device. In addition, switching at a high frequency associated with a fast control period increases the loss in the switching elements of the inverter 5 and the DC-DC converter, leading to a decrease in the efficiency of the on-board charging device (in this case, the first charging device 10X).

[0029] For this reason, for example, as in a second comparative example (second charging device 10Y) shown in Fig. 16, it is possible to supplement the inductance that is insufficient with the coil 7 alone by disposing an additional inductor La between the neutral point 7N of the coil 7 and the external AC power supply 4. In this case, an input inductor Li is formed by a series circuit of the coil 7 and the additional inductor La. However, even in this case, the component cost of the additional inductor La is incurred, and the cost of the in-vehicle charging device is likely to increase due to the need to secure a mounting space for the additional inductor La.

[0030] In view of this, in a third comparative example (third charging device 10Z) shown in Fig. 15, the driving circuit of the rotating electric machine 70 is shared with the second circuit 2 instead of the first circuit 1. Specifically, an inverter 5 is used as a single arm of a step-down chopper equipped with a single-arm half bridge and a choke coil Le, and a coil 7 is used as the choke coil Le. Note that in the third charging device 10Z as well, the above-mentioned DC link capacitor 6 is shared as a decoupling capacitor arranged between the first circuit 1 and the second circuit 2.

[0031] The third charging device 10Z and the in-vehicle charging device 10 of this embodiment have in common that the first circuit 1 is a boost type AC / DC converter (AC / DC Boost Converter), but differ in that the second circuit 2 of the third charging device 10Z is a DC / DC Buck Converter equipped with a step-down chopper, whereas the second circuit 2 of the in-vehicle charging device 10 is an active decoupling circuit. In addition, the third charging device 10Z includes a DC link capacitor 6 between the first circuit 1 and the second circuit 2, and the switching elements of the first circuit 1 and the second circuit 2 are independently controlled for switching. On the other hand, in the in-vehicle charging device 10 of this embodiment, which does not include a decoupling capacitor between the first circuit 1 and the second circuit 2, the switching elements of the first circuit 1 and the second circuit 2 are controlled for switching in cooperation with each other. In particular, the switching elements of the second circuit 2, which is the latter circuit, are controlled to operate in conjunction with the first circuit 1. The details will be described later with reference to Figs. 6 to 13 etc.

[0032] As shown in Fig. 2, the first circuit 1 is configured to include an input inductor Li. In AC-DC conversion, a phase difference occurs between the voltage phase and the current phase due to inductive impedance and capacitive impedance, and the power factor decreases due to the phase difference. The first circuit 1 is configured to include a switching element, and by controlling the switching element, for example, the current phase is adjusted, the phase difference is compensated, and the power factor can be improved. In other words, the first circuit 1 is configured to also function as a power factor correction (PFC) circuit that improves the power factor of DC power converted from AC power supplied from an external AC power source 4.

[0033] In addition, since the first circuit 1 is configured to include a full bridge, it can function as a bidirectional converter capable of AC-DC conversion and DC-AC conversion. For example, the vehicle-mounted charging device 10 can be used as a device having two functions: a function 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. That is, the vehicle-mounted charging device 10 of this embodiment functions as a boost type AC-DC converter (AC / DC Boost Converter) and also functions as a step-down type DC-AC converter (DC / AC Buck Converter).

[0034] In recent years, it has been proposed to use the DC power supply 3 of an electric vehicle or a hybrid vehicle as an emergency power supply in the event of a disaster or the like. The first circuit 1 has a full bridge, so that the DC power supply 3 can be used as such an emergency power supply. Of course, when the use of such a DC power supply 3 is not taken into consideration, the first circuit 1 may be configured as a one-way converter that performs only AC-DC conversion. In this case, the first circuit 1 may be configured to have, for example, a half bridge.

[0035] 2, the in-vehicle charging device 10 includes a grid contactor 13 that electrically connects and disconnects the first circuit 1 and the external AC power source 4. When the grid contactor 13 is closed, the grid contactor 13 is in a conductive state, and the external AC power source 4 and the in-vehicle charging device 10 (first circuit 1) are electrically connected.

[0036] As shown in FIG. 2, the vehicle-mounted charging device 10 includes a function-switching contactor 12 that electrically connects and disconnects the neutral point 7N of the coil 7 and the active filter capacitor Cs. When the function-switching contactor 12 is closed, the neutral point 7N is connected to the negative pole of the DC power supply via the active filter capacitor Cs. As described above, the drive control system of the rotating electric machine 70 and the vehicle-mounted charging device 10 share the main contactor 11. When the inverter 5 functions as the vehicle-mounted charging device 10, the main contactor 11, the function-switching contactor 12, and the grid contactor 13 are all controlled to be closed. That is, with the main contactor 11, the function-switching contactor 12, and the grid contactor 13 all closed, power is converted between the external AC power supply 4 and the DC power supply 3 via the first circuit 1 and the second circuit 2 including the inverter 5.

[0037] When the inverter 5 is used for driving control of the rotating electric machine 70, the main contactor 11 is closed and the function switching contactor 12 and the grid contactor 13 are controlled to be open. That is, with the main contactor 11 closed and the function switching contactor 12 open, power is converted between the DC power source 3 and the rotating electric machine 70 via the inverter 5.

[0038] In this way, by simply changing the connection form of the function switching contactor 12 to the coil 7, it is possible to realize a circuit that can switch between the function of driving and controlling the rotating electric machine 70 and the function of charging the DC power supply 3 with the external AC power supply 4. That is, the in-vehicle charging device 10 can be configured with a simple configuration.

[0039] As described above, the in-vehicle charging device 10 is configured to include the first circuit 1 functioning as an AC-DC converter and the second circuit 2 functioning as an active decoupling circuit. The circuit block diagram of FIG. 3 is a functionally divided version of the circuit block diagram of FIG. 2 for ease of understanding. The first circuit 1 adjusts the power factor of the grid current Igrid supplied from the external AC power source 4 to a value close to "1" while boosting the voltage. However, the first DC power output from the first circuit 1 has a pulsating component caused by harmonics of the AC frequency of the external AC power source 4 superimposed thereon. The inventors' experiments and simulations have revealed that the even-order harmonics of the AC frequency of the external AC power source 4 have a large effect. It has also been found that the pulsating effects of the second and fourth harmonic components of the even-order harmonics are particularly large. The second circuit 2 reduces the pulsation of these harmonic components and supplies the second DC power from which the pulsation is suppressed, preferably the second DC power from which the pulsation is removed, to the DC power source 3 to charge the DC power source 3.

[0040] Here, if the AC voltage supplied from the external AC power supply 4 is the "grid voltage Vgrid" and the AC current is the "grid current Igrid," the input power Pin supplied from the external AC power supply 4 is expressed as the product of the "grid voltage Vgrid" and the "grid current Igrid" as shown in the following formula (1). Assuming that the input power Pin is converted to the first DC power with a power factor of "1," the relationship between the input power Pin and the first DC power can be approximated as shown in the following formula (1). Formula (1) indicates that the first DC power contains a DC component Pdc and an AC component Prpl.

[0041]

number

[0042] The active decoupling circuit functions to cause a current corresponding to the AC component Prpl included in equation (1), i.e., the AC component Prpl included in the first DC power, to flow through the active decoupling circuit so that the output power Pout to the DC power supply 3 is only the DC component Pdc included in equation (1) (equation (2)). The second circuit 2 as an active decoupling circuit operates to make the capacitor power Pcs, which is the power in the active filter capacitor Cs, equal to the AC component Prpl of the first DC power, as shown in the following equation (3).

[0043]

number

number

[0044] Regarding the capacitor power Pcs, the relationship of the following formula (4) holds between the capacitor voltage Vcs and the capacitor current Ics, and therefore the capacitor power Pcs can be controlled by appropriately controlling the capacitor current Ics.

[0045]

number

[0046] As described above, since the inductance of the coil 7 of the rotating electric machine 70 is small, the active decoupling circuit uses the inductor (coil 7) not to store energy but to pass current. Also, in the on-board charging device 10, the capacitor current Ics is not a so-called continuous current but a discontinuous current by pulse width modulation to realize the decoupling action by the active decoupling circuit.

[0047] Constant-current constant-voltage charging control is known 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. In 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. As charging by constant-current charging control progresses, the value of the SOC increases, and the terminal voltage of the DC power source 3 (battery voltage Vbat) also increases from the voltage at the start of charging.

[0048] When the SOC rises to a predetermined value (e.g., 80 to 90%), or when the battery voltage Vbat rises to a preset value (e.g., a switching voltage), 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 supply 3 constant. Since the voltage applied to the DC power supply 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., a full charge voltage), 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.

[0049] Consider a case where such charging control is performed using a charging device configured using a drive circuit (coil 7, inverter 5, etc.) of a rotating electric machine 70, for example, a case where it is performed using a third charging device 10Z illustrated with reference to FIG. 15. In the third charging device 10Z, a DC link capacitor 6 is arranged between a first circuit 1 (AC-DC converter) and a second circuit 2 (DC-DC converter). In the constant current constant voltage charging control, a DC link voltage Vdc corresponding to the terminal voltage of the DC link capacitor 6 is held at a constant voltage value throughout the entire control period. On the other hand, a battery voltage Vbat, which is a voltage of a DC power source 3 to be charged, 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 Vdc and the battery voltage Vbat is large, and losses such as switching losses in the third charging device 10Z (particularly the second circuit 2 in this case) tend to be large.

[0050] Furthermore, in constant current charging control, the battery voltage Vbat increases as the control progresses. In constant current charging control, the battery current Ibat is constant, so the battery power Pbat is small at the beginning of charging control (constant current charging control) and increases as the battery voltage Vbat increases due to the execution of constant current charging control. In other words, the DC power supply 3 is charged with a relatively low charging power at the beginning of charging, and is not charged with the maximum allowable charging power over the entire range of charging control, so that the charging time tends to be long.

[0051] That is, when a conventional charging device (third charging device 10Z) shown in FIG. 15 is used to charge the DC power source 3 using conventional constant-current constant-voltage charging control, there are at least the following problems: (1) the voltage difference between the DC link voltage Vdc, which is the terminal voltage of the DC link capacitor 6, and the battery voltage Vbat becomes large, and (2) the DC power source 3 is not charged at the maximum charging power allowed over almost the entire range of charging control, so that the charging time tends to be long.

[0052] In view of this, in this embodiment, the in-vehicle charging device 10 having the configuration shown in Fig. 2 is used to overcome the above-mentioned problems and is configured to charge the DC power source 3 with high efficiency. Specifically, as shown in Figs. 2 and 3, the DC link capacitor 6 is not disposed between the first circuit 1 and the second circuit 2, but is connected in parallel to the DC power source 3, so that the voltage difference between the DC link voltage Vdc, which is the terminal voltage of the DC link capacitor 6, and the battery voltage Vbat is suppressed from increasing. Furthermore, during the period in which the constant current charging control is conventionally performed and from a state lower than the switching voltage (second voltage) until the switching voltage (second voltage) is reached, constant power charging control is performed as charging control so that the battery current Ibat, which is the current flowing through the DC power source 3, and the charging power (battery power Pbat) based on the battery voltage Vbat, which is the voltage of the DC power source 3, are constant. This allows the DC power source 3 to be charged with the maximum charging power allowed over almost the entire range of charging control, and the charging time can be shortened.

[0053] As shown in FIG. 4, the control device 80 executes constant power charging control as charging control so that the charging power (battery power Pbat) based on the current (battery current Ibat) flowing through the DC power source 3 and the terminal voltage (battery voltage Vbat) of the DC power source 3 is constant (first phase PH1) 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. In the on-board charging device 10 shown in FIG. 2, the DC link capacitor 6 is connected in parallel to the DC power source 3, and the DC link voltage Vdc rises together with the battery voltage Vbat. Although FIG. 4 illustrates a state in which there is a voltage difference between the DC link voltage Vdc and the battery voltage Vbat, they may be substantially the same voltage. In the case of the third charging device 10Z shown in FIG. 15, it is preferable that the DC link voltage Vdc is variably controlled according to the battery voltage Vbat and rises together with the battery voltage Vbat while maintaining a constant voltage difference as shown in FIG. 4.

[0054] In the vehicle-mounted charging device 10 of this embodiment, as described above, it is not necessary to variably control the DC link voltage Vdc, which is the voltage across the terminals of the DC link capacitor 6. Instead, in the vehicle-mounted charging device 10, the capacitor voltage Vcs, which is the voltage across the terminals of the active filter capacitor Cs, is controlled so as to maintain a constant voltage difference (ΔV) with the battery voltage Vbat, as shown in FIG. 5. That is, in constant power charging control, the control device 80 sets a voltage command (capacitor voltage V) so that the terminal voltage (capacitor voltage Vcs) of the active filter capacitor Cs increases in response to an increase in the terminal voltage of the DC power source 3 (battery voltage Vbat). * cs) is set to execute variable DC voltage control. The reason for this will be described later with reference to equation (28) etc.

[0055] Furthermore, as charging control, the control device 80 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 80 reduces the battery power Pbat until it becomes zero, or reduces the battery current Ibat until it becomes zero.

[0056] Incidentally, 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". Also, the charging start voltage Vbat_e, which is the battery voltage Vbat when charging starts and is lower than the "second voltage", can also be called the "third voltage". The full charge voltage Vbat_f and the switching voltage Vbat_s are voltage values ​​that are predetermined 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 predetermined voltage value.

[0057] 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 (full charge 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), such overcharging can be easily suppressed.

[0058] In addition, as charging control, the control device 80 may execute constant voltage charging control similar to the conventional constant current constant voltage charging control described above, instead of 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%).

[0059] As shown in Fig. 4, in the charging control of this embodiment, when the state of charge (SOC) of the DC power supply 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 constant power charging control is executed. When the SOC rises to a predetermined value (e.g., 80 to 90%) or the battery voltage Vbat rises to a preset 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.

[0060] The control form in the control device 80 for realizing the above-mentioned charging control will be described below. Fig. 6 shows a schematic control block diagram of a first control unit 810 that controls the first circuit 1 that functions as an AC-DC converter and a power factor correction circuit, and Fig. 7 shows a schematic control block diagram of a second control unit 820 that controls the second circuit 2 that functions as an active decoupling circuit. The first control unit 810 and the second control unit 820 are part of the control device 80, and are realized by working with software such as a program, with a logic operation processor such as a microcomputer at its core.

[0061] 6, a "grid voltage Vgrid" is an AC voltage indicated by "Vcosωt" and input from the external AC power supply 4. Here, "ω" is the angular velocity, and "t" is the time. In this embodiment, the control device 80 controls the first circuit 1 not by sine wave control but by vector control in a dp axis vector coordinate system, similar to the drive control of the rotating electric machine 70. In the case of sine wave control, the grid voltage Vgrid is represented by "Vsinωt". Also, the "grid current Igrid" is an AC current input from the external AC power supply 4. * "Vgrid_sense" indicates the detected "grid voltage Vgrid", "Igrid_sense" indicates the detected "grid current Igrid", and "Vbat_sense" indicates the detected "battery voltage Vbat". In addition, the effective value of the grid voltage Vgrid (grid voltage effective value Vgrid_rms) is detected by a peak detector (PK_DETECT) provided in the first control unit 810.

[0062] As shown in FIG. 6, the first control unit 810 includes a grid current command feedback calculation unit 815, a grid current command feedforward calculation unit 816, a first voltage command feedback calculation unit 811, a first voltage command feedforward calculation unit 812, a first pulse generation unit 813, and a grid voltage detection unit 819.

[0063] The grid voltage detection unit 819 detects a peak voltage (grid voltage peak value Vgrid_pk), an angular velocity ω, and a waveform "cosωt" from the grid voltage Vgrid for use in a subsequent control block. In this embodiment, a form in which the grid voltage detection unit 819 is configured using a phase locked loop (PLL) is exemplified. As described above, in the case of vector control, "cosωt" is detected as the waveform.

[0064] As shown in FIG. 6 and the following equations (5) and (6), the grid current command feedback calculation unit 815 calculates the battery voltage Vbat and the battery voltage command V * Based on the deviation from bat, proportional and integral control (PI control) is performed to calculate the power value (InputPower) required for charging the DC power source 3, and a feedback grid current command I * Calculate grid_fb.

[0065]

number

number

[0066] In order to make it clear that a detected value is used in equation (5), the battery voltage Vbat is written as "Vbat_sense". The same applies to the signal names with "_sense" added to equation (6) and the following equations. Furthermore, in equation (5), Kp is the proportional gain, and Ki is the integral gain. The same applies to the equations showing proportional-integral control below. As shown in Fig. 6, the product of the value obtained by dividing the grid voltage Vgrid by the square of the grid voltage effective value Vgrid_rms and the calculation result of the PI control based on the deviation of the battery voltage Vbat is the feedback grid current command I * It becomes grid_fb.

[0067] As shown in the following equation (7), the grid current command feedforward calculation unit 816 calculates the battery power command Pb * Based on the grid voltage Vgrid and the battery voltage Vbat, a feedforward grid current command I * Calculate grid_ff.

[0068]

number

[0069] 6, the grid current command feedforward calculation unit 816 includes a loss map (LOSSMAP) that stores the loss values ​​in the AC-DC converter associated with the battery voltage Vbat and the grid voltage effective value Vgrid_rms. The loss of the AC-DC converter obtained from the loss map using the grid voltage effective value Vgrid_rms and the battery voltage Vbat as arguments and the battery power command Pb * The required battery power (Pi) is calculated by adding the required battery power (Pi) and taking into account the loss. The required battery power (Pi) is then multiplied by the square root of 2 and divided by the effective grid voltage Vgrid_rms to obtain the feedforward grid current command I * grid_ff is calculated.

[0070] As shown in FIG. 6 and the following equation (8), the feedback grid current command I *grid_fb and the feedforward grid current command I * The sum of this and grid_ff is the grid current command I * It becomes grid.

[0071]

number

[0072] The first voltage command feedback calculation unit 811 calculates the grid current Igrid and the grid current command I * The first voltage command feedback calculation unit 811 calculates a first feedback voltage command Vfe_fb based on the grid current Igrid and the battery voltage Vbat. * Proportional-integral control (PI control) is executed based on the deviation from the grid to calculate an initial first feedback voltage command Vfe_fb0. Then, the initial first feedback voltage command Vfe_fb0 is divided by the battery voltage Vbat to calculate the first feedback voltage command Vfe_fb.

[0073] The first voltage command feedforward calculation unit 812 calculates the first feedforward voltage command Vfe_ff. Here, in order to generate a sinusoidal voltage command, the wave magnitude (amplitude or peak value) and phase are calculated. The magnitude 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 battery voltage Vbat. The phase is determined taking into consideration three elements: the phase "ωt" of the grid voltage Vgrid, the phase delay due to the input inductor Li (denoted as "θ1"), and the phase delay associated with the delay in grid current control (denoted as "θ2"). Note that the delay in grid current control refers to the number of times that the grid current command Igrid is decreased in one control cycle of the control device 80 after the grid current Igrid is detected. * This corresponds to the delay time associated with the grid being calculated and the first circuit 1 being controlled by the voltage command calculated in the next control period.

[0074] The phase delay "θ1" due to the input inductor Li is expressed by the following formula (9), where the inductance of the input inductor Li is "Li". * grid_pk” is the grid current command peak value.

[0075]

number

[0076] The phase delay "θ2" associated with the delay in grid current control is calculated as a phase equivalent to 1.5 cycles as shown below, because a delay of one control cycle occurs in the calculation of the voltage command. By performing a correction for 1.5 cycles, it becomes possible to correct the average voltage over the entire carrier cycle one cycle ahead, in which the control calculation results are reflected.

[0077] θ2=ω (1.5 cycles of grid current control / 1[s])

[0078] Based on these, an initial first feedforward voltage command Vfe_ff0 having a sinusoidal waveform is defined as shown in the following equation (10).

[0079]

number

[0080] Incidentally, since a normal sine wave has positive and negative values ​​with zero as the center of amplitude, a known conversion process such as a shift process is performed to generate a pulse with a positive digital value. For example, if the domain of the initial first feedforward voltage command Vfe_ff0 is "-1 to 1", "1" is added to "Vfe_ff0" to set the domain to "0 to 2", and in order to fit within the range of "1", "1 / 2" is multiplied to obtain the first feedforward voltage command Vfe_ff. This makes it possible to express the sine wave-shaped first feedforward voltage command Vfe_ff in the domain of "0 to 1". In addition, in the case of sine wave control, since "1-sinωt" is calculated in the calculation of the feedforward term and the domain is already "0 to 2", it is only necessary to multiply by "1 / 2" without adding "1".

[0081] The first pulse generating unit 813 generates a pulse (pulse for pulse width modulation) for controlling the switching of the switching elements (first switch S1, second switch S2, third switch S3, fourth switch S4) of the first circuit 1 based on the first voltage command Vfe, which is the sum of the first feedback voltage command Vfe_fb and the first feedforward voltage command Vfe_ff. The final switching pulse is generated by a known calculation based on the carrier (first carrier CA_fe) and the first voltage command Vfe, and therefore a detailed description thereof will be omitted. When the control device 80 is configured by a digital processor such as a microcomputer, for example, the first voltage command Vfe is converted into a counter value to generate the switching pulse.

[0082] The first voltage command Vfe indicates a duty in pulse width modulation control. For example, when the first voltage command Vfe is a duty in an arm on the side of the third switch S3 and the fourth switch S4, the duty in the arm on the opposite side, that is, the arm on the side of the first switch S1 and the second switch S2, is indicated by "1-Vfe", which is the inverse of the first voltage command Vfe.

[0083] As described above, the second circuit 2 functioning as an active decoupling circuit attenuates the pulsating component of the current charging the DC power supply 3 by passing a current of the pulsating component through the active filter capacitor Cs (coil 7). The second circuit 2 controls the switching of the inverter 5 to pass an appropriate current through the active filter capacitor Cs. In the inverter 5, all upper-stage switching elements are collectively controlled to be turned on and off, and all lower-stage switching elements are collectively controlled to be turned on and off. The collectively controlled upper-stage switching elements correspond to the fifth switch S5, and the collectively controlled lower-stage switching elements correspond to the sixth switch S6.

[0084] 7, the second control unit 820 that controls the second circuit 2 includes a capacitor current command feedback control unit 821, a capacitor current command feedforward control unit 822, a capacitor voltage command feedforward control unit 823, and a second pulse generating unit 824. * As shown in FIG. 7 and the following formula (11), the capacitor current feedback command I * cs_fb, and the capacitor current feedforward command I calculated by the capacitor current command feedforward control unit 822. * It is calculated as the sum with cs_ff.

[0085]

number

[0086] As shown in FIG. 7 and the following formula (12), the capacitor current command feedback control unit 821 receives the capacitor voltage command V * Based on the deviation between the active filter capacitor Cs and the capacitor voltage Vcs, PI control is performed to calculate the power value (Power) to be consumed by the active filter capacitor Cs.

[0087]

number

[0088] The capacitor current command feedback control unit 821 further divides the derived power value (Power) by the capacitor voltage Vcs as shown in the following equation (13), to obtain the capacitor current feedback command I * Calculate cs_fb.

[0089]

number

[0090] The capacitor current command feedforward control unit 822 controls the battery power command Pb * Based on the battery voltage Vbat, the capacitor current command I * The peak value (Ics2f) of the second harmonic (2f) and the peak value (Ics4f) of the fourth harmonic (4f) of cs are obtained. Values ​​optimized in advance by experiments and simulations are stored in the lookup table. As shown in FIG. 7 and the following formula (14), for the values ​​obtained from the lookup table, the peak value of the second harmonic (Ics2f) is multiplied by "cos2ωt" and the peak value of the fourth harmonic (Ics4f) is multiplied by "cos(4ωt+π / 2)", and the second harmonic and the fourth harmonic are added to obtain the capacitor current feedforward command I * cs_ff is calculated.

[0091]

number

[0092] The capacitor voltage command feedforward control unit 823 calculates a second voltage command Vadc for controlling the switching of the inverter 5 in the second circuit 2. The slope of the capacitor current Ics flowing through the active filter capacitor Cs differs depending on whether the capacitor current Ics is positive or negative. As shown in Figs. 12 and 13, the capacitor current Ics becomes triangular shaped due to pulse width modulation control. The slope of the capacitor current Ics corresponds to the slope of this triangular wave. The slope of the capacitor current Ics when the capacitor current Ics is positive (Ics_posi_slope) and the slope of the capacitor current when the capacitor current Ics is negative (Ics_nega_slope) are respectively expressed by the following equations (15) and (16). It should be noted that "Lm" is the inductance of the coil 7 of the rotating electric machine 70.

[0093]

number

number

[0094] The capacitor voltage command feedforward control unit 823 further calculates the capacitor current command I * A difference between cs and the capacitor current Ics is obtained, and the difference is divided by the gradient of the capacitor current shown in equation (15) or (16), to calculate a second voltage command Vadc (active decoupling voltage command).

[0095] The second pulse generating unit 824 generates pulses (pulses for pulse width modulation) for controlling the switching of the switching elements (fifth switch S5, sixth switch S6) of the second circuit 2 based on the second voltage command Vadc and the second carrier CA_adc. The final switching pulses are generated by a known calculation based on the carrier (second carrier CA_adc) and the second voltage command Vadc, and therefore a detailed description is omitted. When the control device 80 is configured with a digital processor such as a microcomputer, for example, the second voltage command Vadc is converted into a counter value to generate the switching pulses.

[0096] 8 to 11 show the current flow in the second circuit 2 that functions as an active decoupling circuit. The waveform diagram in FIG. 12 shows the relationship between the grid voltage Vgrid, the grid current Igrid, the capacitor current Ics, and the capacitor voltage Vcs. As described above, in the second circuit 2, the capacitor current Ics is controlled, so FIG. 12 shows the capacitor current command I * The waveform diagram in FIG. 13 also shows the capacitor current command I cs, which is switched by pulse width modulation control. * cs, the capacitor current Ics, and the switching pulses.

[0097] As shown in Fig. 13, when the capacitor current Ics is positive, the fifth switch S5 is on / off controlled, and the sixth switch S6 is fixed to the off state. When the capacitor current Ics is negative, the sixth switch S6 is on / off controlled, and the fifth switch S5 is fixed to the off state. Also, as shown in Figs. 12 and 13, the capacitor current Ics is not a so-called continuous current, but a discontinuous current due to pulse width modulation. Therefore, the current that actually flows as an AC current through the active filter capacitor Cs is equal to the capacitor current command I * Therefore, the capacitor current command I * cs is set to a value twice the current that should actually flow through the active filter capacitor Cs.

[0098] Figures 8 and 9 show the current flow when the capacitor current Ics flowing through the active filter capacitor Cs is a positive value with the direction of the arrow shown in Figure 3 being positive, and the active filter capacitor Cs is being charged, which corresponds to the current flow during the period marked "Charging" in Figures 12 and 13. Figures 10 and 11 show the current flow when the capacitor current Ics flowing through the active filter capacitor Cs is a negative value and the active filter capacitor Cs is being discharged, which corresponds to the current flow during the period marked "Discharging" in Figures 12 and 13.

[0099] As described above, the inverter 5 is configured to have a plurality of arms in parallel, in which an upper-stage switching element and a lower-stage switching element are connected in series between the positive and negative poles of the direct current, according to the number of phases of the multi-phase alternating current. In this embodiment, the inverter 5 is configured to have three arms. When the inverter 5 functions as an active decoupling circuit, all the upper-stage switching elements are simultaneously switched and controlled as the fifth switch S5, and all the lower-stage switching elements are simultaneously switched and controlled as the sixth switch S6. That is, the inverter 5 having multiple phase arms corresponding to the multi-phase alternating current is used as an inverter (switching circuit) having a single-phase arm. Since the current flows in a distributed manner in the multiple arms, it is easy to suppress the wear of the inverter 5 even if the inverter 5 is used as a part of the in-vehicle charging device 10.

[0100] In addition, since the current of approximately the same magnitude flows through each of the coils 7 of the multiple phases, excluding individual differences and errors, even if the coils 7 are also used as the in-vehicle charging device 10, almost no torque is generated in the rotor. Since the charging of the DC power source 3 is performed in a state where the vehicle is stopped, it is not preferable for torque to be generated in the rotor. For example, it is possible to cut off the power transmission from the rotor to the wheels by a clutch or the like, or to restrict the rotation of the output member connected to the wheels or the rotation of the rotor by a so-called parking brake or the like. However, in these cases, the mechanism of the vehicle drive device 9 becomes complicated, or a mechanical load is generated on the gears of the vehicle drive device 9 or the like. In this embodiment, the rotor is controlled so that no torque is generated, so that the in-vehicle charging device 10 can be appropriately configured without generating almost no mechanical load on the gears of the vehicle drive device 9 or the like.

[0101] 13, the inverter 5 is controlled by the modulated pulse to three states: (1) a first state in which all upper-stage switching elements (fifth switches S5) are on (ON) and all lower-stage switching elements (sixth switches S6) are off (OFF), (2) a second state in which the fifth switches S5 are off and all sixth switches S6 are on, and (3) a third state in which both the fifth switch S5 and the sixth switch S6 are off. In the third state, all switching elements of the inverter 5 are off.

[0102] Fig. 8 shows the flow of current when the capacitor current Ics flowing through the active filter capacitor Cs increases with a positive value, with the direction of the arrow shown in Fig. 2 and Fig. 3 being positive, to charge the active filter capacitor Cs. In the waveform diagrams shown in Fig. 12 and Fig. 13, during the period marked "Charging", the capacitor current Ics increases in proportion to the capacitor current command I *This corresponds to a period during which the amplitude of the first DC power increases from the center of amplitude of the first DC power to the wave height (peak). The switching elements of the inverter 5 are controlled to be in the first state. The AC component Prpl of the first DC power is consumed to charge the active filter capacitor Cs, and substantially only the DC component Pdc of the first DC power is supplied to the DC power supply 3 as the second DC power.

[0103] Fig. 9 shows the current flow when the capacitor current Ics is decreasing with a positive value and charging the active filter capacitor Cs. In the waveform diagrams shown in Figs. 12 and 13, during the period marked "Charging", the capacitor current Ics is greater than the capacitor current command I * This corresponds to the period during which the current Ics decreases from the wave height (peak) of the active filter capacitor Cs toward the center of amplitude. The switching elements of the inverter 5 are controlled to be in the third state. The capacitor current Ics decreases while circulating between the active filter capacitor Cs and the freewheeling diode connected in parallel to the lower-stage switching element, or through the lower-stage switching element (when using the reverse conduction of the body diode or E-GaN transistor).

[0104] That is, in the "charging" phase, the lower-stage switching element (sixth switch S6) is controlled to be constantly off, and the upper-stage switching element (fifth switch S5) is switched by pulse width modulation control.

[0105] FIG. 11 shows the current flow when the active filter capacitor Cs is discharged while the absolute value of the capacitor current Ics is decreasing with a negative value. In the waveform diagrams shown in FIG. 12 and FIG. 13, during the period marked "Discharging", the absolute value of the capacitor current Ics is greater than the capacitor current command I *This corresponds to a period during which the amplitude of the first DC power is decreasing from the wave height (bottom) of the active filter capacitor Cs toward the center of the amplitude. The switching elements of the inverter 5 are controlled to be in the third state. The current flowing due to the charge discharged from the active filter capacitor Cs flows to the DC power supply 3 through a freewheel diode connected in parallel to the upper-stage switching element, or through the upper-stage switching element (when reverse conduction of a body diode or E-GaN transistor is used). That is, the AC component Prpl of the first DC power is reduced by the charge discharged from the active filter capacitor Cs, and approximately only the DC component Pdc of the first DC power is supplied to the DC power supply 3 as the second DC power.

[0106] FIG. 10 shows the current flow when the capacitor current Ics is negative and the absolute value of the capacitor current Ics is increasing to discharge the active filter capacitor Cs. In the waveform diagrams shown in FIG. 12 and FIG. 13, during the period marked "Discharging", the absolute value of the capacitor current Ics increases in proportion to the capacitor current command I * This corresponds to the period during which the amplitude of the capacitor current Ics increases from the center to the wave height (bottom). The switching elements of the inverter 5 are controlled to be in the second state. The absolute value of the capacitor current Ics increases while circulating between the active filter capacitor Cs and the lower-stage switching elements.

[0107] That is, in the “Discharging” phase, in contrast to the “Charging” phase, the upper-stage switching element (the fifth switch S5) is controlled to be always off, and the lower-stage switching element (the sixth switch S6) is switched by pulse width modulation control.

[0108] As shown in FIG. 12, the capacitor current command I * The phase of cs coincides with the phase of the grid voltage Vgrid and the phase of the grid current Igrid. The grid voltage Vgrid and the grid current Igrid are expressed by the following formulas (17) and (18), with their amplitudes being "Vgrid_peak" and "Igrid_peak", respectively.

[0109]

number

number

[0110] When the pulsating component is consumed by the active filter capacitor Cs, the power of the pulsating component and the power in the active filter capacitor Cs must satisfy the relationship of the above formula (3). That is, the capacitor power Pcs must be controlled to be equal to the AC component Prpl of the first DC power. The capacitor current command I * cs is the capacitor current command I * The amplitude of cs is I * The capacitor voltage Vcs is expressed as cs_peak by the following equation (19). The phase of the capacitor voltage Vcs lags behind the capacitor current Ics by π / 2. The capacitor voltage Vcs is expressed by the following equation (20) with the amplitude of the capacitor voltage Vcs as Vcs_peak.

[0111]

number

number

[0112] Moreover, the left side "Prpl" and the right side "Pcs" of the formula (3) are expressed by the following formulas (21) and (22), respectively.

[0113]

number

number

[0114] Therefore, from equations (21) and (22), the amplitude of the capacitor current Ics required to cancel the pulsation of the power supplied to the DC power supply 3 is expressed by the following equation (23).

[0115]

number

[0116] As described above, in this embodiment, since control is performed using a discontinuous current, the amplitude of the necessary harmonic component of the capacitor current command is expressed by the following equation (24).

[0117]

number

[0118] As is clear from equation (24), the capacitor current command I * The magnitude of the capacitor current command Ics varies depending on the pulsation of the battery voltage Vbat and the battery current Ibat, and the capacitor voltage Vcs. Therefore, when the load size or the battery voltage Vbat changes, the capacitor current command I * The size of cs also changes.

[0119] In addition, the inventors' Fast Fourier Transform (FFT) analysis of the battery current Ibat revealed that the harmonic components that appear as pulsations and have a large influence are the second harmonic and the fourth harmonic. When the active decoupling circuit is not applied, the influence of the second harmonic component is the largest. When the active decoupling circuit is applied to suppress the second harmonic component, the second harmonic component is attenuated while the fourth harmonic component becomes large. For this reason, the active decoupling circuit is tuned to suppress both the second harmonic component and the fourth harmonic component. Therefore, the subscript "cs_rpl" shown in equations (21) to (24) includes "cs2f_rpl" corresponding to the second harmonic component and "cs4f_rpl" corresponding to the fourth harmonic component. For this reason, the final capacitor current command I *cs is expressed by the following equations (25) to (27).

[0120]

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[0121] In addition, if the battery voltage Vbat increases and the capacitor voltage Vcs is constant, the capacitor current Ics increases when the active decoupling circuit is subjected to switching control. This increases the loss in the second circuit 2. Therefore, as shown in FIG. 5, the capacitor voltage command V * The value of cs is set (see equation (28)).

[0122]

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[0123] Incidentally, in a configuration such as the third charging device 10Z shown in FIG. 15, that is, in a configuration in which a DC link capacitor 6 is disposed between the first circuit 1 and the second circuit 2, pre-charge control of the DC link capacitor 6 is often required as a start sequence when starting charging control.

[0124] In the third charging device 10Z, when the charging control is started from a state in which the DC link capacitor 6 is almost completely discharged, the DC link capacitor 6 is rapidly charged. That is, when the charging control is started, a large transient current flows through the path from the charge supplier to the DC link capacitor 6. Since the steady current flowing through the path during the execution of the 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 the pre-charge control for charging the DC link capacitor 6 prior to the charging control is executed, it is possible to suppress the flow of a large transient current accompanying the start of the charging control, and the third charging device 10Z can be easily configured simply.

[0125] For example, in the pre-charge control, the control device 80 controls the main contactor 11 so that the DC power source 3 and the DC link capacitor 6 are connected, and closes the first contact 11a of the main contactor. Even when the SOC of the DC power source 3 is low enough to require charging control, a charge sufficient to charge the DC link capacitor 6 often remains. Therefore, the DC link capacitor 6 is charged by the energy of the DC power source 3. Since no element such as a switching element is present in the path connecting the DC power source 3 and the DC link capacitor 6, the DC link capacitor 6 can be safely and quickly charged. During the execution of the pre-charge control, the grid contactor 13 is controlled to be in an open state.

[0126] Here, an example of a start sequence, which is a sequence at the start of the charge control including the pre-charge control, will be described. Before the start of the charge control, the main contactor 11, the function switching contactor 12, and the grid contactor 13 are all in an open state, and the switching elements of the first circuit 1 and the second circuit 2 are also all in an off state. The control device 80 first controls the main contactor first contact 11a of the main contactor 11 to be closed. As a result, the DC link capacitor 6 is charged by the DC power source 3 as described above. When the SOC of the DC power source 3 is low, the DC link voltage rises to a voltage lower than the battery voltage Vbat at the time of full charge. The control device 80 can determine the end of the pre-charge control based on, for example, the detection result of the DC link voltage sensor 61, when the DC link voltage reaches the battery voltage Vbat and the voltage no longer rises.

[0127] Next, the control device 80 opens the main contactor first contact 11a and closes the main contactor second contact 11b, closes the function switching contactor 12, and closes the grid contactor 13. Thereafter, the control device 80 controls the switching of the switching elements of the first circuit 1 and the second circuit 2 to charge the DC power supply 3 with power supplied from the external AC power supply 4.

[0128] On the other hand, as shown in Figs. 2 and 3, the vehicle-mounted charging device 10 of this embodiment does not have a DC link capacitor 6 between the first circuit 1 and the second circuit 2, nor does it have any passive components including other capacitors. The DC link capacitor 6 is connected in parallel to the DC power source 3 both when driving the rotating electric machine 70 and when charging the DC power source 3. In other words, even when the DC link capacitor 6 is rapidly charged from a discharged state, a current flows directly from the DC power source 3 without passing through other components such as a switching element. Therefore, the above-mentioned precharge control of the DC link capacitor 6 is not necessary, and charging of the DC power source 3 can be started quickly. That is, the vehicle-mounted charging device 10 of this embodiment can simplify the start sequence.

[0129] FIG. 14 is a time chart showing an example of a start sequence of the in-vehicle charging device 10 of this embodiment. At time t1, charging control is started. "ACDC" at the top of FIG. 14 indicates the state of charging control accompanied by AC-DC conversion, "ON" indicates the state in which charging control is being executed, and "OFF" indicates the state in which charging control is not being executed. When charging control is started, at least the main contactor 11 is closed first. When the main contactor 11 is closed, the DC link capacitor 6 is charged. In FIG. 14, "Vbat" indicates the inter-terminal voltage of the DC link capacitor 6, and at time t2, "Vbat" rises to the voltage "Vref1" of the DC power source 3 at that time.

[0130] At time t2, the function switching contactor 12 and the grid contactor 13 are closed, the grid current Igrid starts to be supplied from the external AC power source 4, and the AC-DC converter of the first circuit 1 and the active decoupling circuit (ADC) of the second circuit 2 also start to operate. * increases from time t2 within the range of the change rate limit in the control cycle, and at time t3, the required battery power command Pb * (100%). The capacitor voltage Vcs of the active filter capacitor Cs rises to a voltage "Vref2 (=Vref1-ΔV)" corresponding to the battery voltage Vbat, and the battery current Ibat also reaches the reference current (Iref1) in the constant power charging control. After time t3, the DC power supply 3 is charged by the constant power charging control described above.

[0131] In this way, the in-vehicle charging device 10 of this embodiment can quickly start charging control of the DC power source 3 without requiring pre-charge control of the capacitor.

[0132] As described above, the pulsating components of the harmonics of the frequency of the external AC power source 4 are superimposed on the DC power output from the first circuit 1 equipped with the AC-DC converter. In many cases, in order to generate DC power from which the pulsating components have been removed, a DC-DC converter is provided following the first circuit, and the DC power source 3 is charged with the DC power converted by the DC-DC converter. In this case, a decoupling capacitor having a relatively large capacitance and a relatively large size is often placed between the AC-DC converter and the DC-DC converter. According to the in-vehicle charging device 10 of this embodiment, the first circuit 1 equipped with the AC-DC converter and the second circuit 2 equipped with an active decoupling circuit that attenuates the pulsating components are connected without passing through passive components including such a decoupling capacitor. Therefore, it is easy to keep the size of the in-vehicle charging device 10 small. In addition, the inverter 5 for driving the rotating electric machine 70 and the coil 7 of the rotating electric machine 70 are used as switching elements and inductors that constitute the active decoupling circuit, which makes it easy to suppress an increase in the overall size of the in-vehicle device.

[0133] Furthermore, according to this configuration, by executing constant power charging control, the DC power supply 3 can be charged with the maximum allowable charging power, and the charging time can be shortened. In addition, in constant power charging control, the grid current supplied from the external AC power supply 4 is variably controlled by feedforward control and feedback control based on the battery voltage, the command value of the battery voltage, the grid voltage, and the battery power command. Therefore, the DC power supply 3 can be efficiently charged with an appropriate current according to the conditions, rather than a uniform current as in constant current charging control.

[0134] As described above, the peak value of the capacitor voltage Vcs, which is the terminal voltage of the active filter capacitor Cs, is smaller than the battery voltage Vbat, and the capacitor voltage Vcs is variably controlled so that the difference between the DC component of the capacitor voltage Vcs and the DC component of the battery voltage Vbat becomes a preset differential voltage ΔV.

[0135] This maintains a constant voltage difference (differential voltage ΔV) between the battery voltage Vbat and the capacitor voltage Vcs, thereby preventing an increase in loss in the second circuit 2 caused by the rise in the battery voltage Vbat as charging progresses.

[0136] As described above, the inverter 5 is switched and controlled so that an AC current corresponding to the pulsation of the even-order harmonic components of the grid current Igrid becomes the capacitor current Ics flowing through the active filter capacitor Cs and the coil 7.

[0137] As described above, according to the experiments and simulations by the inventors, it was found that the prominent pulsating components in the DC current converted from AC to DC by the first circuit 1 are the even-order harmonic components of the frequency of the external AC power supply. Therefore, the second circuit 2 can appropriately attenuate the pulsating components by controlling the switching so that the current of the even-order harmonic components becomes the capacitor current Ics.

[0138] In this embodiment, as described above, the even-order harmonic components are second harmonic components and fourth harmonic components, the phase of the second harmonic component of the capacitor current Ics is the same as that of the grid voltage Vgrid, and the phase of the fourth harmonic component of the capacitor current Ics is ahead of the phase of the second harmonic component by π / 2. That is, the phase of the grid voltage Vgrid is "ωt", the phase of the second harmonic component of the capacitor current Ics is "2ωt", and the phase of the fourth harmonic component of the capacitor current Ics is "4ωt+π / 2". As described above, the capacitor current command I * The peak value (Ics2f) of the second harmonic (2f) of cs and the peak value (Ics4f) of the fourth harmonic (4f) of cs are the battery power command Pb * and is calculated based on the battery voltage Vbat.

[0139] According to this embodiment, not only the second harmonic component, which has a relatively large influence, but also higher-order pulsating components can be attenuated. Therefore, the pulsating components superimposed on the DC current converted from AC to DC by the first circuit 1 can be appropriately attenuated.

[0140] In this embodiment, the pulsation to be attenuated by the active decoupling circuit corresponds to the second harmonic and the fourth harmonic among the even-order harmonic components. However, the active decoupling circuit may be configured to pass a capacitor current Ics so as to attenuate, for example, only the second harmonic component according to the amplitude of the pulsation that the DC power supply 3 can tolerate. Naturally, the active decoupling circuit may be configured to pass a capacitor current Ics that also corresponds to higher-order harmonic components such as the sixth harmonic and the eighth harmonic in addition to the second harmonic and the fourth harmonic. [Explanation of symbols]

[0141] 1: first circuit, 2: second circuit, 3: DC power supply, 4: external AC power supply, 5: inverter, 7: coil, 7N: neutral point, 9: vehicle drive device, 10: on-board charging device, 70: rotating electric machine, 80: control device, Cs: active filter capacitor, Ibat: battery current, Ics: capacitor current, Ics2f: peak value of second harmonic of capacitor current command, Ics4f: peak value of fourth harmonic of capacitor current command, Igrid: grid current, Pb * : Battery power command, Pbat: Battery power, Vbat: Battery voltage, Vcs: Capacitor voltage, Vgrid: Grid voltage, V * bat: Battery voltage command (battery voltage command value), ΔV: Differential voltage (voltage difference between battery voltage and capacitor voltage)

Claims

1. An on-board charging device for charging a DC power supply of a vehicle drive device, the on-board charging device comprising: a rotating electric machine having multiple phase coils connected to each other at a neutral point and serving as a drive power 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 an external AC power supply, a first circuit including an AC / DC converter for converting power between AC power from the external AC power source and a first DC power; a second circuit including an active decoupling circuit configured to include the inverter, the coils of a plurality of phases, and an active filter capacitor, and configured to attenuate a pulsating component from the first DC power to generate a second DC power for charging the DC power supply; a control device that controls the first circuit and the second circuit, a DC side terminal of the first circuit and a DC side terminal of the inverter are connected without any other passive component; The active filter capacitor is connected between the neutral point of the coil and a negative pole of a direct current; 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 battery voltage, which is a terminal voltage of the DC power supply, reaches the second voltage from a state lower than the second voltage, so that a battery current, which is a current flowing through the DC power supply, and a charging power based on the battery voltage are constant; In the constant power charging control, the grid current supplied from the external AC power supply to the DC power supply is feedback control based on a deviation between the command value of the battery voltage and the battery voltage, and a grid voltage which is a voltage value of the AC power supplied from the external AC power supply; and An on-board charging device that is variably controlled by feedforward control based on the grid voltage, the battery voltage, and a battery power command for charging the DC power supply.

2. a peak value of a capacitor voltage, which is a voltage across the active filter capacitor, is less than the battery voltage; 2. The in-vehicle charging device according to claim 1, wherein the capacitor voltage is variably controlled so that a difference between a DC component of the capacitor voltage and a DC component of the battery voltage becomes a preset differential voltage.

3. 3. The on-board charging device according to claim 1, wherein the inverter is switched and controlled so that an AC current corresponding to pulsations of even-order harmonic components of the grid current becomes a capacitor current flowing through the active filter capacitor and the coil.

4. the even-order harmonic components are second-order harmonic components and fourth-order harmonic components, the phase of the second harmonic component of the capacitor current is in phase with the grid voltage; The phase of the fourth harmonic component of the capacitor current is π / 2 ahead of the phase of the second harmonic component, 4. The in-vehicle charging device according to claim 3, wherein the peak value of the second harmonic component of the capacitor current and the peak value of the fourth harmonic component of the capacitor current are calculated based on the battery power command and the battery voltage.

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