JP2022006573A - Motor drive system - Google Patents

Abstract

To provide a motor drive system capable of sufficiently consuming a surplus of regenerative power.SOLUTION: At a time of regeneration of a motor drive system (YES in S1), an HV-ECU calculates regenerative power Wrb (S3-S7) and determines whether or not surplus power Wsp is generated (S9). In a case where the surplus power Wsp is generated (YES in S9), the HV-ECU distributes the surplus power Wsp to motor increase power Wm and converter increase power Wc (S13). The HV-ECU then determines a frequency f and an amplitude ΔVH of a harmonic wave to be superposed on a system voltage command (S15 and S17). The HV-ECU outputs a power consumption command LOSSUP including the converter increase power Wc, the frequency f and the amplitude ΔVH of a harmonic wave component and the motor increase power Wm to an MG-ECU 80 (S19).SELECTED DRAWING: Figure 8

Description

The present disclosure relates to a motor drive system.

Japanese Patent Application Laid-Open No. 2010-246263 (Patent Document 1) adjusts the loss of the motor to suppress overcharging of the battery when the braking torque is output when the SOC (State Of Charge) of the battery is high SOC. The motor drive device to be used is disclosed. When the loss amount of the motor is insufficient for the required loss amount, this motor drive device shifts the power loss line for realizing the loss amount to be consumed by the motor to the d-axis side to reduce the loss of the motor. Increase (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2010-246263

In recent years, the loss of the motor has been reduced due to the improvement of the motor and the like. Therefore, it may not be possible to sufficiently consume the surplus of the regenerative power only by adjusting the loss of the motor (that is, reducing the efficiency of the motor).

The present disclosure has been made to solve the above problems, and an object thereof is to provide a motor drive system capable of sufficiently consuming a surplus of regenerative power.

The motor drive system according to this disclosure includes an inverter for driving a motor generator, a converter that boosts the DC voltage of the inverter to a voltage higher than the battery voltage, and a control that controls the converter so that the DC voltage of the inverter becomes a command value. Equipped with a device. At the time of regeneration of the motor drive system, the control device superimposes a harmonic on the command value of the DC voltage of the inverter when the regenerative power by the motor generator exceeds the upper limit of the charging power of the battery.

According to the above configuration, when the regenerated power of the motor generator exceeds the upper limit of the charging power of the battery during the regeneration of the motor drive system (that is, when the surplus of the regenerated power is generated), the inverter Harmonics are superimposed on the command value of the DC voltage. When harmonics are superimposed on the command value, the iron loss and copper loss of the reactor contained in the boost converter increase, and the switching loss and on-loss of the switching element included in the boost converter increase. That is, the efficiency of the boost converter is reduced. Due to the reduced efficiency of the boost converter, more regenerative power is consumed in the boost converter. Therefore, by superimposing the harmonics on the command value of the DC voltage of the inverter, the surplus of the regenerative power can be sufficiently consumed.

According to the present disclosure, it is possible to provide a motor drive system capable of sufficiently consuming a surplus of regenerative power.

It is an overall block diagram of the motor drive system which concerns on embodiment. It is a figure for demonstrating surplus electric power. It is a functional block diagram of the HV-ECU regarding the calculation of the regenerative power. It is a figure for demonstrating the system voltage command at the time of superimposing harmonics. It is a figure for demonstrating the reactor current at the time of superimposing a harmonic on a system voltage command. It is a figure for demonstrating the frequency of a harmonic superposed with a system voltage command. It is a figure for demonstrating the amplitude of a harmonic superposed with a system voltage command. It is a flowchart which shows the procedure of the process executed by the HV-ECU.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

<Overall configuration>
FIG. 1 is an overall configuration diagram of a motor drive system 100 according to the present embodiment. The motor drive system 100 according to the present embodiment can be applied to, for example, a hybrid vehicle, an electric vehicle, a fuel cell vehicle (hereinafter, also collectively referred to as “vehicle”) and the like. With reference to FIG. 1, the motor drive system 100 includes a motor generator 10, a power control unit (PCU) 20, a battery 30, and a control device 50. The control device 50 includes a battery ECU (Electronic Control Unit) 60, an HV-ECU 70, and an MG-ECU 80.

The motor generator 10 is, for example, a drive electric motor that generates torque for driving the drive wheels of a vehicle. The motor generator 10 is an AC rotary electric machine, and is configured as, for example, a three-phase AC rotary electric machine in which a permanent magnet is embedded in a rotor (not shown). Further, the motor generator 10 is further provided with the function of a generator, and is configured to have the functions of an electric motor and a generator.

The motor generator 10 is provided with a rotation angle sensor (resolver) 45 and a temperature sensor 46.

The rotation angle sensor (resolver) 45 detects the rotation angle θ of the motor generator 10 and outputs a signal indicating the detection result to the MG-ECU 80. The MG-ECU 80 can detect the rotation speed (rotation speed) Nm of the motor generator 10 from the change speed of the rotation angle θ detected by the rotation angle sensor 45.

The temperature sensor 46 detects the temperature Tm of the motor generator 10 and outputs a signal indicating the detection result to the HV-ECU 70.

The battery 30 is composed of a secondary battery such as a nickel hydrogen battery or a lithium ion battery. The secondary battery may be a secondary battery having a liquid electrolyte between the positive electrode and the negative electrode, or may be a secondary battery (all-solid-state battery) having a solid electrolyte. Further, the battery 30 may be configured by an electric double layer capacitor or the like.

The battery 30 is provided with a monitoring unit 35. The monitoring unit 35 detects the voltage (battery voltage) VB of the battery 30, the input / output current (battery current) IB of the battery 30, and the temperature (battery temperature) TB of the battery 30, and outputs a signal indicating the detection result to the battery. Output to ECU 60. In the present embodiment, the battery current IB shows a negative value when the battery 30 is charged, and shows a positive value when the battery 30 is discharged.

The PCU 20 boosts the DC power supplied from the battery 30 and converts it into AC power to supply the motor generator 10. Further, the PCU 20 converts the AC power generated by the motor generator 10 into DC power and supplies it to the battery 30. That is, the battery 30 can transfer power to and from the motor generator 10 via the PCU 20.

The PCU 20 includes a boost converter 21, an inverter 22, a voltage sensor 41, a current sensor 42, a voltage sensor 43, a capacitor C1, and a capacitor C2.

The capacitor C1 is connected between the power line PL1 and the power line NL. The capacitor C1 smoothes the battery voltage VB and supplies it to the boost converter 21. The voltage sensor 41 detects the voltage across the capacitor C1, that is, the voltage VL between the power lines PL1 and NL, and outputs a signal indicating the detection result to the MG-ECU 80.

The boost converter 21 boosts the battery voltage VB according to the control signals S1 and S2 from the MG-ECU 80, and supplies the boosted voltage to the power lines PL2 and NL. Further, the boost converter 21 charges the battery 30 by stepping down the DC voltage between the power lines PL2 and NL supplied from the inverter 22 according to the control signals S1 and S2 from the MG-ECU 80.

Specifically, the boost converter 21 includes a reactor L, switching elements Q1 and Q2, and diodes D1 and D2. The reactor L is connected between the connection node of the switching elements Q1 and Q2 and the power line PL1. As each of the switching elements Q1 and Q2 and the switching elements Q3 to Q8 described later, for example, an IGBT (Insulated Gate Bipolar Transistor), a MOS (Metal Oxide Semiconductor) transistor, a bipolar transistor or the like can be used. The diodes D1 and D2 are connected in antiparallel between the collector and the emitter of the switching elements Q1 and Q2, respectively.

Further, the boost converter 21 includes a temperature sensor 47. The temperature sensor 47 detects the temperatures TQ1 and TQ2 of the switching element Q1 and the switching element Q2, respectively, and outputs a signal indicating the detection result to the HV-ECU 70. The HV-ECU 70 calculates the temperature TQ of the switching elements Q1 and Q2 by using the temperatures TQ1 and TQ2 received from the temperature sensor 47. For example, the HV-ECU 70 calculates the average value of the temperature TQ1 and the temperature TQ2 as the temperature TQ of the switching elements Q1 and Q2.

The current sensor 42 detects the reactor current IL flowing through the power line PL1 and outputs a signal indicating the detection result to the MG-ECU 80.

The capacitor C2 is connected between the power line PL2 and the power line NL. The capacitor C2 smoothes the DC voltage supplied from the boost converter 21 and supplies it to the inverter 22. The voltage sensor 43 detects the voltage across the capacitor C2, that is, the voltage (hereinafter also referred to as “system voltage”) VH between the power lines PL2 and NL connecting the boost converter 21 and the inverter 22, and outputs a signal indicating the detection result. Output to MG-ECU 80.

The inverter 22 includes a U-phase arm 221, a V-phase arm 222, and a W-phase arm 223. Each phase arm is connected in parallel between the power line PL2 and the power line NL. The U-phase arm has switching elements Q3 and Q4 connected in series with each other. The V-phase arm 222 has switching elements Q5 and Q6 connected in series with each other. The W-phase arm 223 has switching elements Q7 and Q8 connected in series with each other. Diodes D3 to D8 are connected in antiparallel between the collector and the emitter of each switching element Q3 to Q8.

The midpoint of each phase arm is connected to each phase end of each phase coil of the motor generator 10. The intermediate point of the switching elements Q3 and Q4 is connected to one end of the U-phase coil of the motor generator 10. The intermediate point of the switching elements Q5 and Q6 is connected to one end of the V-phase coil of the motor generator 10. The intermediate point of the switching elements Q7 and Q8 is connected to one end of the W phase coil of the motor generator 10. The other ends of the three coils of the U-phase, V-phase and W-phase of the motor generator 10 are commonly connected to the neutral point.

When the system voltage VH is supplied, the inverter 22 converts the DC voltage into an AC voltage and drives the motor generator 10 according to the control signals S3 to S8 from the MG-ECU 80. As a result, the motor generator 10 is controlled by the inverter 22 so as to generate torque according to the torque command value Trqcom.

Further, at the time of regeneration of the motor drive system 100, the inverter 22 converts the AC voltage generated by the motor generator 10 into a DC voltage according to the control signals S3 to S8 from the MG-ECU 80, and the converted DC voltage (system voltage VH). ) Is supplied to the boost converter 21 via the capacitor C2.

The current sensor 44 detects the three-phase currents (motor currents) iu, iv, and iwa flowing through the motor generator 10, and outputs a signal indicating the detection result to the MG-ECU 80. Since the sum of the instantaneous values of the three-phase currents iu, iv, and iwa is zero, the current sensor 44 has two phases of motor current (for example, V-phase current iv and W-phase current iwa) as shown in FIG. It suffices to arrange it so that it can be detected.

The control device 50 includes a battery ECU 60, an HV-ECU 70, and an MG-ECU 80. The battery ECU 60, HV-ECU 70, and MG-ECU 80 are input / output devices for exchanging signals with various connected sensors and other ECUs, and memories used for storing various control programs, maps, and the like. It is configured to include a central processing unit (CPU) for executing a control program, a counter for timing, and the like.

The battery ECU 60 manages the state of the battery 30. The battery ECU 60 calculates the SOC of the battery 30 based on the detection result received from the monitoring unit 35. SOC is a percentage of the current charge capacity of the battery 30. As a method for calculating the SOC, various known methods such as a method based on current value integration (coulomb count) or a method based on estimation of open circuit voltage (OCV) can be adopted. The battery ECU 60 outputs a signal indicating the calculated SOC to the HV-ECU 70.

Further, the battery ECU 60 calculates the input limit Win and the output limit Wout of the battery 30. The input limit Win is the allowable charging power indicating the maximum value of the power that the battery 30 can accept, that is, the upper limit of the charging power of the battery 30. The input limit Win is set to a value of 0 or less. When the input limit Win is 0, it means that the battery 30 cannot be charged. When the input limit Win becomes smaller (the absolute value of the input limit Win becomes larger), it means that the power that can be received by the battery 30 becomes larger. The battery ECU 60 sets the input limit Win, for example, based on the SOC of the battery 30 and the battery temperature TB. The battery ECU 60 sets the input limit Win to be larger (smaller as an absolute value) as the SOC of the battery 30 is higher. Further, the battery ECU 60 sets the input limit Win to be larger (smaller as an absolute value) as the battery temperature TB is lower.

The output limit Wout is an allowable discharge power indicating the maximum value of the power that can be output from the battery 30, that is, the upper limit of the discharge power of the battery 30. The output limit Wout is set to a value of 0 or more. When the output limit Wout is 0, it means that the battery 30 cannot be discharged. The increase in the output limit Wout means that the power that can be output from the battery 30 increases. The battery ECU 60 sets the output limit Wout based on, for example, the SOC of the battery 30 and the battery temperature TB. The battery ECU 60 sets the output limit Wout smaller as the SOC of the battery 30 is lower. Further, the battery ECU 60 sets the output limit Wout smaller as the battery temperature TB is lower.

The battery ECU 60 outputs a signal indicating the calculated input limit Win and output limit Wout to the HV-ECU 70.

The HV-ECU 70 receives the detection signals from various connected sensors. Various sensors connected to the HV-ECU 70 include, for example, an accelerator position sensor 91 and a brake position sensor 92. The accelerator position sensor 91 detects the amount of depression of the accelerator pedal by the driver. The brake position sensor 92 detects the amount of depression of the brake pedal by the driver. The accelerator position sensor 91 and the brake position sensor 92 output a signal indicating the detection result to the HV-ECU 70.

Further, the HV-ECU 70 receives various information such as the motor rotation speed Nm, the system voltage VH, and the reactor current IL from the MG-ECU 80. The HV-ECU 70 may be configured to acquire the reactor current IL and the system voltage VH from the current sensor 42 and the voltage sensor 43, respectively. Further, the HV-ECU 70 may be configured to acquire the rotation angle θ from the rotation angle sensor 45 and calculate the rotation speed (motor rotation speed) Nm of the motor generator 10.

The HV-ECU 70 calculates the required driving force based on the accelerator opening degree or the like determined by the amount of depression of the accelerator pedal. The HV-ECU 70 generates a torque command value Trqcom for the motor generator 10 based on the calculated required driving force, and outputs the generated torque command value Trqcom to the MG-ECU 80.

The MG-ECU 80 controls the operation of the boost converter 21 and the inverter 22 so that the motor generator 10 outputs the torque according to the torque command value Trqcom. That is, the MG-ECU 80 generates control signals S1 to S8 for controlling the boost converter 21 and the inverter 22, and outputs the control signals to the boost converter 21 and the inverter 22.

During the boosting operation of the boost converter 21, the MG-ECU 80 feedback-controls the system voltage VH of the capacitor C2 so that the system voltage VH becomes a voltage command value (hereinafter also referred to as “system voltage command”) VHcom. Generate S2.

Further, the MG-ECU 80 sets a d-axis current command and a q-axis current command from the torque command value Trqcom, and the d-axis current and the q-axis converted based on these and the motor currents iu, iv, iwa and the rotation angle θ. Feedback control is performed based on the deviation from the current (d-axis current command-d-axis current, q-axis current command-q-axis current). The MG-ECU 80 sets a d-axis voltage command and a q-axis voltage command so that the deviation becomes small, and coordinates the set d-axis voltage command and q-axis voltage command into a three-phase voltage command (two-phase three-phase conversion). )do. The MG-ECU 80 generates control signals S3 to S8 so that a voltage corresponding to a three-phase voltage command is applied to each of the three-phase coils of the motor generator 10.

When the MG-ECU 80 receives a signal RGE indicating that the vehicle (motor drive system 100) has entered the regenerative mode from the HV-ECU 70, the MG-ECU 80 is a control signal to convert the AC voltage generated by the motor generator 10 into a DC voltage. S3 to S8 are generated and output to the inverter 22. As a result, the inverter 22 converts the AC voltage generated by the motor generator 10 into a DC voltage and supplies it to the boost converter 21. The MG-ECU 80 generates control signals S1 and S2 so as to step down the DC voltage supplied from the inverter 22, and outputs the control signals to the boost converter 21. As a result, the AC voltage generated by the motor generator 10 is converted into a DC voltage, stepped down, and supplied to the battery 30.

<Consumption of surplus power>
Here, at the time of regeneration of the motor drive system 100, the magnitude of the regenerative power Wrb of the motor drive system 100 exceeds the magnitude of the input limit Win of the battery 30, and the surplus power Wsp (= | Wrb | − | Win |). May occur. FIG. 2 is a diagram for explaining the surplus power Wsp. FIG. 2 shows an example of the time transition of the power consumed and generated by the motor generator 10 (hereinafter, also referred to as “motor power”). The horizontal axis of FIG. 2 shows time, and the vertical axis shows motor power.

Before time t1, the motor drive system 100 is in the power running mode, and the power of the battery 30 is consumed by the motor generator 10.

At time t1, the motor drive system 100 enters the regenerative mode and the motor generator 10 generates electricity. Between time t1 and time t2, since the magnitude of the electric power (regenerative electric power Wrb) generated by the motor generator 10 is less than the magnitude of the input limit Win, all of the regenerative electric power Wrb is charged to the battery 30. As described above, the input limit Win changes as the SOC of the battery 30 rises due to charging, but in FIG. 2, the input limit Win is shown as constant for the sake of facilitation of explanation.

At time t2, the magnitude of the regenerative power Wrb exceeds the magnitude of the input limit Win. That is, after time t2, surplus power Wsp is generated.

If the battery 30 is charged with power exceeding the size of the input limit Win, the battery 30 will be overcharged. Therefore, the surplus portion of the regenerative power Wrb exceeding the size of the input limit Win (surplus power Wsp) ) Is desired to be appropriately consumed without being used for charging the battery 30. As a method for this, it is conceivable to consume surplus power Wsp by, for example, reducing the efficiency of the motor generator 10.

However, there is a possibility that the surplus power Wsp cannot be sufficiently consumed only by reducing the efficiency of the motor generator 10.

Therefore, in the present embodiment, in addition to the decrease in the efficiency of the motor generator 10, the efficiency of the boost converter 21 is further decreased to sufficiently consume the surplus power Wsp. The details will be described below in order.

First, the HV-ECU 70 calculates the regenerative power Wrb in the motor drive system 100. Then, the HV-ECU 70 compares the calculated regenerative power Wrb with the input limit Win of the battery 30 to calculate the surplus power Wsp.

FIG. 3 is a functional block diagram of the HV-ECU 70 regarding the calculation of the regenerative power Wrb. With reference to FIG. 3, the HV-ECU 70 includes a motor power calculation unit 71, a motor loss calculation unit 72, a motor power calculation unit 73, a converter loss calculation unit 74, and a regenerative power calculation unit 75.

The motor power calculation unit 71 integrates the motor rotation speed Nm and the torque command value Trqcom to calculate the power of the motor generator 10.

The motor loss calculation unit 72 calculates the loss in the motor generator 10 using the first loss map with the motor rotation speed Nm, the torque command value Trqcom, and the system voltage VH as arguments. The first loss map is a map for calculating the loss in the motor generator 10 from the motor rotation speed Nm, the torque command value Trqcom, and the system voltage VH. The first loss map can be predetermined based on experimental results, simulation results, specifications of the motor generator 10, and the like.

The motor power calculation unit 73 adds the power of the motor generator 10 calculated by the motor power calculation unit 71 and the loss in the motor generator 10 calculated by the motor loss calculation unit 72 to obtain the motor power (of the motor generator 10). Regenerative power) is calculated.

The converter loss calculation unit 74 calculates the loss in the boost converter 21 using the second loss map with the system voltage VH and the reactor current IL as arguments. The second loss map is a map for calculating the loss in the boost converter 21 from the system voltage VH and the reactor current IL. The second loss map can be predetermined based on the experimental result, the simulation result, the specifications of the boost converter 21, and the like.

The regenerative power calculation unit 75 calculates the regenerative power Wrb by adding the motor power calculated by the motor power calculation unit 73 and the loss in the boost converter 21 calculated by the converter loss calculation unit 74.

When the regenerative power Wrb is calculated with reference to FIGS. 1 and 2 again, the HV-ECU 100 calculates the value obtained by subtracting the size of the input limit Win from the size of the regenerative power Wrb as the surplus power Wsp.

The HV-ECU 70 divides the surplus power Wsp into power consumed due to a decrease in the efficiency of the motor generator 10 and power consumed due to a decrease in the efficiency of the boost converter 21. That is, the HV-ECU 70 distributes the surplus power Wsp to the motor increasing power Wm that increases the power consumption of the motor generator 10 and consumes it, and the converter increasing power Wc that increases and consumes the power consumption of the boost converter 21. ..

For example, the HV-ECU 70 distributes the surplus power Wsp by using the temperature Tm of the motor generator 10 and the temperature TQ of the switching elements Q1 and Q2 of the boost converter 21. For example, the HV-ECU 70 distributes the surplus power Wsp so that the power consumed by the boost converter 21 (converter increasing power Wc) becomes large when the temperature Tm of the motor generator 10 is relatively high, and the switching elements Q1 and Q2 When the temperature TQ is relatively high, the surplus power Wsp is distributed so that the power consumed by the motor generator 10 (motor increasing power Wm) becomes large. In the present embodiment, the HV-ECU 70 takes the ratio of the temperature Tm of the motor generator 10 and the temperature TQ of the switching elements Q1 and Q2 as arguments, and uses the distribution map to set the motor increasing power Wm and the converter increasing power Wc. Determine the distribution ratio. The distribution map is a map in which the relationship between the ratio of the temperature Tm and the temperature TQ and the distribution ratio of the motor increasing power Wm and the converter increasing power Wc is defined. The distribution map is stored in the memory of the HV-ECU 70, for example. The HV-ECU 70 divides the surplus power Wsp into a motor increasing power Wm and a converter increasing power Wc based on the distribution ratio obtained by using the distribution map.

The HV-ECU 70 outputs information including the motor increasing power Wm and the converter increasing power Wc to the MG-ECU 80 as a power consumption command LOSSUP.

When the MG-ECU 80 receives the power consumption command LOSSUP from the HV-ECU 70, the MG-ECU 80 reduces the efficiency of the motor generator 10 and the boost converter 21 based on the power consumption command LOSSUP. That is, the MG-ECU 80 controls the PCU 20 so that the power consumption of the boost converter 21 increases by the converter increasing power Wc so that the power consumption of the motor generator 10 increases by the motor increasing power Wm.

First, the efficiency reduction of the motor generator 10 will be described. The MG-ECU 80 stores a plurality of operation lines that define the relationship between the current advance angle and the current effective value. The current advance angle indicates the angle of the current vector based on the d-axis current command and the q-axis current command in the dq coordinate system. The current effective value indicates the square root of the sum of the square value of the d-axis current command and the square value of the q-axis current command, that is, the magnitude of the current vector. The MG-ECU 80 sets the d-axis current command and the q-axis current command from the current effective value and the current advance angle determined at the intersection of the torque command value Trqcom and the operation line.

The operating line includes an optimum line and a plurality of loss lines. The optimum line is an operation line that defines the combination of the current effective value and the current advance angle that minimizes the current effective value. The loss line is an operation line that defines a combination of the current effective value and the current advance angle in which the current effective value is larger than the optimum line. The MG-ECU 80 can increase the power consumption of the motor generator 10 (decrease the efficiency of the motor generator 10) by selecting the loss line having a larger current effective value from the plurality of loss lines. ). In the MG-ECU 80, the motor generator 10 operates by selecting the optimum line as the operation line during normal operation. When the MG-ECU 80 receives the power consumption command LOSSUP from the HV-ECU 70, the MG-ECU 80 selects an appropriate loss line from a plurality of loss lines according to the power to be consumed by the motor generator 10 (motor increase power Wm).

Next, the efficiency reduction of the boost converter 21 will be described. When the MG-ECU 80 receives the power consumption command LOSSUP from the HV-ECU 70, the voltage command value of the system voltage VH (system voltage command VHcom) is such that the power to be consumed by the boost converter 21 (converter increase power Wc) is consumed. Superimpose harmonics on.

FIG. 4 is a diagram for explaining a system voltage command VHcom when harmonics are superimposed. FIG. 5 is a diagram for explaining a reactor current IL when harmonics are superimposed on the system voltage command VHcom. Time is shown on the horizontal axis of FIGS. 4 and 5. The vertical axis of FIG. 4 shows the voltage. The vertical axis of FIG. 5 shows the current.

The solid line L3 in FIG. 4 shows the system voltage command VHcom when the harmonics are not superimposed, and the solid line L4 shows the system voltage command VHcom when the harmonics are superimposed. The solid line L5 in FIG. 5 shows the reactor current IL when the harmonics are not superimposed on the system voltage command VHcom, and the solid line L6 shows the reactor current IL when the harmonics are superimposed on the system voltage command VHcom. ..

When a harmonic is superimposed on the system voltage command VHcom, the system voltage command VHcom fluctuates as shown by the solid line L4 in FIG. 4, and the reactor current IL fluctuates as shown by the solid line L6 in FIG. This increases the iron loss and copper loss of the reactor L. Further, the fluctuation of the reactor current IL increases the switching loss and the on-loss of the switching elements Q1 and Q2. That is, the efficiency of the boost converter 21 is lowered by superimposing harmonics on the system voltage command VHcom.

The HV-ECU 70 determines the frequency f and the amplitude ΔVH of the harmonics superimposed on the system voltage command VHcom as follows.

FIG. 6 is a diagram for explaining the frequency f of the harmonics superimposed on the system voltage command VHcom. The horizontal axis of FIG. 6 shows the motor rotation speed Nm, and the vertical axis shows the frequency f.

The HV-ECU 70 determines the frequency f of the harmonics as either the frequency f1 or the frequency f2 (<f1), for example, based on the motor rotation speed Nm. For example, when the motor rotation speed Nm is N1, the HV-ECU 70 determines the harmonic frequency f to f1. For example, when the motor rotation speed Nm is N3, the HV-ECU 70 determines the harmonic frequency f to f2.

The frequency f1 and the frequency f2 are preset, for example, by the controllability of the PCU 20. The frequency f1 and the frequency f2 are set so as to avoid the electric primary frequency, the electric sixth frequency, and the electric twelfth frequency of the motor generator 10. This is to avoid resonance with the LC circuit (reactor L and capacitor C2) of the PCU 20.

The motor rotation speed Nx, which is a switching point between the frequency f1 and the frequency f2, is, for example, a rotation speed at which the margin with respect to the electric 12th frequency of the frequency f1 and the margin with respect to the electric 6th frequency of the frequency f2 are equal.

In the present embodiment, the frequency f of the harmonic is determined to be either the frequency f1 or the frequency f2, but the selectable frequency may be three or more. good.

FIG. 7 is a diagram for explaining the amplitude ΔVH of the harmonics superimposed on the system voltage command VHcom. FIG. 7 shows the relationship between the harmonic frequency f, the converter increasing power Wc, and the harmonic amplitude ΔVH. These relationships are defined as, for example, an amplitude map and are stored in the memory of the HV-ECU 70.

The HV-ECU 70 determines the amplitude ΔVH of the harmonic using the amplitude map with the frequency f of the harmonic and the converter increasing power Wc as arguments. For example, when the harmonic frequency f is f1 and the converter increasing power Wc is W1, the HV-ECU 70 determines the harmonic amplitude ΔVH to be ΔVH11. When the harmonic frequency f is f1 and the converter increasing power Wc is W2, the HV-ECU 70 determines the harmonic amplitude ΔVH to be ΔVH12 (> Vm11). When the harmonic frequency f is f2 and the converter increasing power Wc is W1, the HV-ECU 70 determines the harmonic amplitude ΔVH to be ΔVH21 (> Vm11). When the harmonic frequency f is f2 and the converter increasing power Wc is W2, the HV-ECU 70 determines the harmonic amplitude ΔVH to be ΔVH22 (> Vm21).

The relationship of ΔVH21> Vm11 is set so that the higher the frequency, the larger the iron loss, and the higher the frequency, the larger the current change in a unit time and the larger the copper loss, so that the amplitude ΔVH is small. However, it is possible to secure the power consumption.

<Processing executed by HV-ECU>
FIG. 8 is a flowchart showing a procedure of processing executed by the HV-ECU 70. The flowchart shown in FIG. 8 is repeatedly executed by the HV-ECU 70 at predetermined control cycles. A case where each step of the flowchart shown in FIG. 8 (hereinafter, the step is abbreviated as “S”) is realized by software processing by the HV-ECU 70 will be described, but a part or all of the steps are manufactured in the HV-ECU 70. It may be realized by the hardware (electric circuit).

In S1, the HV-ECU 70 determines whether or not the accelerator has been released based on the detection signal of the accelerator position sensor 91. In other words, the HV-ECU 70 determines whether or not the motor drive system 100 has entered the regenerative mode. If it is determined that the accelerator is off (YES in S1), the HV-ECU 70 advances the process to S3. If it is determined that the accelerator is not off (NO in S1), the HV-ECU 70 advances the process to S21.

In S3, the HV-ECU 70 calculates the regenerative power (motor power) by the motor generator 10. Specifically, the HV-ECU 70 integrates the motor rotation speed Nm and the torque command value Trqcom to calculate the power of the motor generator 10. Further, the HV-ECU 70 calculates the loss in the motor generator 10 using the first loss map with the motor rotation speed Nm, the torque command value Trqcom and the system voltage VH as arguments. The HV-ECU 70 calculates the motor power by adding the power of the motor generator 10 and the loss in the motor generator 10.

In S5, the HV-ECU 70 calculates the loss in the boost converter 21. Specifically, the HV-ECU 70 calculates the loss in the boost converter 21 using the second loss map with the system voltage VH and the reactor current IL as arguments.

In S7, the HV-ECU 70 calculates the regenerative power Wrb by adding the motor power and the loss in the boost converter 21.

In S9, the HV-ECU 70 determines whether or not the surplus power Wsp is generated. Specifically, the HV-ECU 70 determines whether or not the magnitude of the regenerative power Wrb is larger than the magnitude of the input limit Win of the battery 30. If it is determined that the magnitude of the regenerative power Wrb is larger than the magnitude of the input limit Win of the battery 30 (YES in S9), the HV-ECU 70 advances the process to S11. .. When it is determined that the magnitude of the regenerative power Wrb is equal to or less than the magnitude of the input limit Win of the battery 30 (NO in S9), the HV-ECU 70 processes the process in S21. Proceed.

In S11, the HV-ECU 70 calculates the magnitude of the surplus power Wsp. Specifically, the HV-ECU 70 calculates the magnitude of the surplus power Wsp by subtracting the magnitude of the input limit Win from the magnitude of the regenerative power Wrb (Wsp = | Wrb | − | Win |).

In S13, the HV-ECU 70 distributes the surplus power Wsp to the motor increasing power Wm and the converter increasing power Wc. The HV-ECU 70 divides the surplus power Wsp into the motor increasing power Wm and the converter increasing power Wc by using the distribution map with the ratio of the temperature Tm of the motor generator 10 and the temperature TQ of the switching elements Q1 and Q2 as arguments.

In S15, the HV-ECU 70 determines the frequency f of the harmonic component to be superimposed on the system voltage command VHcom. Specifically, the HV-ECU 70 determines the frequency f of the harmonic component based on the motor rotation speed Nm.

In S17, the HV-ECU 70 determines the amplitude ΔVH of the harmonic component superimposed on the system voltage command VHcom. Specifically, the HV-ECU 70 determines the amplitude ΔVH of the harmonic component using the amplitude map with the converter increasing power Wc determined in S13 and the frequency f determined in S15 as arguments.

In S19, the HV-ECU 70 outputs the power consumption command LOSSUP to the MG-ECU 80. The power consumption command LOSSUP includes a converter increasing power Wc, a frequency f and an amplitude ΔVH of harmonic components superimposed on the system voltage command VHcom, and a motor increasing power Wm. The MG-ECU 80 that has received the power consumption command LOSSUP reduces the efficiency of the motor generator 10 and the efficiency of the boost converter 21 based on the power consumption command LOSSUP.

In S21, the HV-ECU 70 advances the processing to the return without outputting the power consumption command LOSSUP.

As described above, in the present embodiment, when the magnitude of the regenerative power Wrb exceeds the magnitude of the input limit Win of the battery 30 (that is, when the surplus power Wsp is generated) at the time of regeneration of the motor drive system 100. HV-ECU 70 and MG-ECU 80 superimpose harmonics on the system voltage command VHcom. When harmonics are superimposed on the system voltage command VHcom, the iron loss and copper loss of the reactor L included in the boost converter 21 increase, and the switching loss and on-loss of the switching elements Q1 and Q2 included in the boost converter 21. Will increase. That is, the efficiency of the boost converter 21 is reduced. As the efficiency of the boost converter 21 decreases, more regenerative power is consumed in the boost converter 21. As a result, the surplus of the regenerative power can be sufficiently consumed.

Further, the HV-ECU 70 uses the temperature Tm of the motor generator 10 and the temperature TQ of the switching elements Q1 and Q2 of the boost converter 21 to consume the surplus power Wsp due to the decrease in the efficiency of the motor generator 10 (motor increasing power). Wm) and the power consumed by the decrease in efficiency of the boost converter 21 (converter increasing power Wc). For example, the HV-ECU 70 distributes the surplus power Wsp so that the converter increasing power Wc becomes large when the temperature Tm of the motor generator 10 is relatively high, and when the temperature TQ of the switching elements Q1 and Q2 is relatively high. Distributes the surplus power Wsp so that the motor increasing power Wm becomes large. As a result, the surplus power Wsp can be sufficiently consumed while suppressing abnormal heat generation in the motor generator 10 and the boost converter 21.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present disclosure is set forth by the claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims.

10 motor generator, 20 PCU, 21 boost converter, 22 inverter, 30 battery, 35 monitoring unit, 41,43 voltage sensor, 42,44 current sensor, 45 rotation angle sensor, 46,47 temperature sensor, 50 controller, 60 battery ECU, 70 HV-ECU, 71 Motor power calculation unit, 72 Motor loss calculation unit, 73 Motor power calculation unit, 74 Converter loss calculation unit, 75 Regenerative power calculation unit, 80 MG-ECU, 91 Accelerator position sensor, 92 Brake position Sensor, 100 motor drive system, C1, C2 capacitors, D1 to D8 diodes, L reactor, NL, PL1, PL2 power lines, Q1 to Q8 switching elements.

Claims (1)

It ’s a motor drive system.
Inverter for driving the motor generator and
A converter that boosts the DC voltage of the inverter to a voltage higher than that of the battery,
A control device for controlling the converter so that the DC voltage becomes a command value is provided.
At the time of regeneration of the motor drive system, the control device superimposes a harmonic on the command value when the regenerative power of the motor generator exceeds the upper limit of the charging power of the battery.

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