Control device for an electric vehicle

Abstract

The present disclosure relates to a control device (40) for an electric vehicle (1), the electric vehicle comprising: a DC power supply (10); an electric motor (30); an inverter (20) that converts DC power supplied from the DC power supply (10) into AC power and outputs the AC power to the electric motor (30); and an inverter control unit (100) that controls the inverter (20) and controls the input voltage to the electric motor (30). When a predetermined high-frequency component is included in a parameter correlated with the input voltage, the inverter control unit (100) performs correction by adding a component that cancels the high-frequency component to the input voltage, and controls the electric motor (30) based on the corrected input voltage. Thereby, it is possible to reduce the multiple component of the electrical frequency.

Description

Technical Field

[0001] The present invention relates to a control device for an electric vehicle. Background Art

[0002] In Patent Document 1, in a drive system of a three-phase AC motor, in order to reduce power supply voltage ripple generated by switching of an inverter, correction control of adding a third-harmonic component to a voltage command of the inverter is performed.

[0003] Prior Art Documents

[0004] Patent Document 1: Japanese Patent No. 5472475 Gazette Summary of the Invention

[0005] Technical Problem to be Solved by the Invention

[0006] In the configuration described in Patent Document 1, although ripple of a switching frequency component can be reduced by a countermeasure against power supply voltage ripple, a countermeasure against power supply current ripple or motor torque ripple is not considered, and thus a multiple component of the electrical frequency cannot be reduced, and there is room for improvement.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for an electric vehicle that can reduce a multiple component of the electrical frequency.

[0008] Technical Solution for Solving the Problem

[0009] The present invention is a control device for an electric vehicle, the electric vehicle including: a DC power supply; a three-phase AC motor; an inverter that converts DC power supplied from the DC power supply into AC power and outputs the AC power to the three-phase AC motor; and a control unit that controls the inverter and controls an input voltage to the three-phase AC motor. The control device is characterized in that when a parameter related to the input voltage includes a predetermined high-frequency component, the control unit performs correction of adding a component that cancels the high-frequency component to the input voltage, and controls the three-phase AC motor based on the corrected input voltage.

[0010] According to this configuration, when a parameter related to the input voltage to the three-phase AC motor includes a predetermined high-frequency component, by performing correction of adding a component that cancels the high-frequency component to the input voltage, a multiple component of the electrical frequency can be reduced.

[0011] In addition, the high-frequency component may be a 6n-th component.

[0012] According to this configuration, a countermeasure against a 6n-th component ripple of a parameter becomes possible.

[0013] In addition, the component for canceling the high-frequency component may include at least one of the 6n-1th component and the 6n+1th component.

[0014] According to this configuration, by adjusting the 6n-1th component and the 6n+1th component on the AC side, the 6nth component ripple of the parameter can be reduced.

[0015] In addition, the parameter may include at least one of the power supply current and the motor torque.

[0016] According to this configuration, countermeasures against the power supply current ripple and the motor torque ripple become possible, and multiple objectives required by the control device can be achieved simultaneously.

[0017] In addition, the control device may switch between the first correction control and the second correction control according to the operating point of the three-phase AC motor. The first correction control is a control for performing the correction in such a way as to cancel only the 6nth component of the power supply current among the power supply current and the motor torque, and the second correction control is a control for performing the correction in such a way as to cancel only the 6nth component of the motor torque among the power supply current and the motor torque.

[0018] According to this configuration, since the first correction control and the second correction control are switched and implemented, mutual interference between the control for reducing the power supply current ripple and the control for reducing the motor torque ripple can be avoided.

[0019] In addition, the parameter may include the magnetic flux.

[0020] According to this configuration, since distortion of the magnetic flux can be suppressed, harmonic iron loss can be reduced. Thereby, harmonic iron loss can be reduced and the efficiency of the system can be improved.

[0021] In addition, the control device may switch between the correction control and the normal control according to the operating point of the three-phase AC motor. The correction control is a control for performing the correction in such a way as to cancel the 6nth component of the magnetic flux, and the normal control is a control for not performing the correction.

[0022] According to this configuration, since the correction control and the normal control are switched and implemented according to the state of the motor, a balance between reducing magnetic flux distortion and ensuring efficiency can be achieved.

[0023] In addition, the parameter may include at least one of the power supply current, the motor torque, and the magnetic flux.

[0024] According to this configuration, countermeasures against the power supply current ripple, the motor torque ripple, and the harmonic iron loss become possible, and multiple objectives required by the control device can be achieved simultaneously.

[0025] In addition, the control device can switch the first correction control, the second correction control, and the third correction control according to the operating point of the three-phase AC motor. The first correction control is a control for performing the correction in such a way as to cancel only the 6n-th component of the power supply current among the power supply current, the motor torque, and the magnetic flux. The second correction control is a control for performing the correction in such a way as to cancel only the 6n-th component of the motor torque among the power supply current, the motor torque, and the magnetic flux. The third correction control is a control for performing the correction in such a way as to cancel only the 6n-th component of the magnetic flux among the power supply current, the motor torque, and the magnetic flux.

[0026] According to this configuration, since the first correction control, the second correction control, and the third correction control are switched and implemented, it is possible to avoid mutual interference among the control for reducing the power supply current ripple, the control for reducing the motor torque ripple, and the control for reducing the harmonic iron loss.

[0027] Effects of the Invention

[0028] In the present invention, in the case where a predetermined high-frequency component is included in a parameter correlated with the input voltage to the three-phase AC motor, by performing correction for adding a component that cancels the high-frequency component to the input voltage, it is possible to reduce the multiple components of the electrical frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a system configuration diagram schematically showing the configuration of the electric vehicle in the embodiment.

[0030] Figure 2 It is a diagram for explaining the generation mechanism of the power supply current ripple.

[0031] Figure 3 It is a waveform diagram showing the 6th ripple of the power supply current.

[0032] Figure 4 It is a diagram for explaining the power variation on the DC side.

[0033] Figure 5 It is a diagram for explaining the main causes of the distortion of the motor current.

[0034] Figure 6 It is an explanatory diagram showing the countermeasure method for the power supply current ripple.

[0035] Figure 7 It is a diagram for explaining the waveform when distortion is intentionally added to the inverter voltage as a countermeasure for the power supply current ripple.

[0036] Figure 8 It is a waveform diagram showing the waveform of the power supply current when the correction control is implemented.

[0037] Figure 9 It is a diagram for explaining the torque ripple of the motor.

[0038] Figure 10 It is an explanatory diagram showing countermeasure methods for coping with the torque ripple of the motor.

[0039] Figure 11 It is a mapping diagram for explaining the correction control switched according to the operating point of the motor.

[0040] Figure 12 It is a flowchart showing the switching processing flow.

[0041] Figure 13 It is a diagram for explaining the distortion of the magnetic flux.

[0042] Figure 14 It is an explanatory diagram showing countermeasure methods for coping with harmonic iron loss.

[0043] Figure 15 It is a mapping diagram for explaining the correction control of the magnetic flux implemented according to the operating point of the motor. Detailed implementation manners

[0044] Hereinafter, with reference to the accompanying drawings, a control device for an electric vehicle according to an embodiment of the present invention will be specifically described. In addition, the present invention is not limited to the embodiments described below.

[0045] Figure 1 It is a system configuration diagram schematically showing the configuration of the electric vehicle in the embodiment. As Figure 1 shown, the electric vehicle 1 includes a DC power supply 10, an inverter 20, a motor 30, and a control device 40. This electric vehicle 1 is a vehicle with the motor 30 as a power source. In addition, the motor drive system 50 in the electric vehicle 1 is configured to include the DC power supply 10, the inverter 20, and the motor 30.

[0046] The DC power supply 10 is a power storage device capable of storing electric power for supplying to the motor 30. This DC power supply 10 is constituted by a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery, for example.

[0047] The inverter 20 is a power conversion device that converts the DC power supplied from the DC power supply 10 into AC power and outputs the converted AC power to the motor 30. This inverter 20 is electrically connected to the control device 40, and its driving state is controlled by the control device 40. Specifically, the inverter 20 applies a three-phase voltage to the motor 30 based on a three-phase voltage command from the control device 40. That is to say, the inverter 20 is a three-phase inverter.

[0048] The inverter 20 includes: a U-phase arm including a p-side switching element and an n-side switching element; a V-phase arm including a p-side switching element and an n-side switching element; and a W-phase arm including a p-side switching element and an n-side switching element. Each switching element of the inverter 20 is constituted by, for example, an IGBT (Insulated Gate Bipolar Transistor). In addition, each phase arm of the inverter 20 is connected in parallel between a positive line connected to the positive electrode of the DC power supply 10 and a negative line connected to the negative electrode of the DC power supply 10. A diode through which current flows from the emitter side to the collector side is connected to the switching element of the inverter 20. And the midpoints of the p-side switching element and the n-side switching element of each phase arm are respectively connected to each phase coil (U-phase coil, V-phase coil, W-phase coil) of the motor 30.

[0049] The motor 30 is a driving power source in the electric vehicle 1 and is a three-phase AC motor-generator in which permanent magnets are embedded in the rotor. That is, the motor 30 is a three-phase AC motor. The motor 30 generates torque by flowing three-phase current according to the applied three-phase voltage. The motor 30 is mechanically connected to the drive wheels of the electric vehicle 1 and can generate torque for driving the electric vehicle 1. When the electric vehicle 1 brakes, the motor 30 can also receive the input of the kinetic energy of the electric vehicle 1 for regeneration (power generation). For example, when the electric vehicle 1 is a hybrid vehicle, the motor 30 is mechanically connected to the engine and can be regenerated by the power of the engine and can also assist the power of the engine.

[0050] In addition, after a three-phase voltage is applied to the motor 30 through the inverter 20, motor current flows in each phase coil of the motor 30. The motor current includes: a U-phase current Iu flowing in the U-phase coil of the motor 30; a V-phase current Iv flowing in the V-phase coil of the motor 30; and a W-phase current Iw flowing in the W-phase coil of the motor 30.

[0051] The control device 40 is an electronic control device that controls the operation of the motor drive system 50. The control device 40 includes a processor and a memory. The processor includes a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field-Programmable Gate Array), etc. The memory is a main storage device and includes a RAM (Random Access Memory), a ROM (Read Only Memory), etc. Further, the control device 40 loads the program pre-stored in the ROM into the working area of the memory for execution, and controls each component through the execution of the program, thereby realizing functions that meet the predetermined purpose. Further, the control device 40 can execute control (ripple reduction control) for reducing the ripple generated in the motor drive system 50 according to the control program pre-stored in the ROM.

[0052] In addition, signals from various sensors are input to the control device 40. As the signals input to the control device 40, the rotational position of the motor 30 from a rotational position sensor that detects the rotational position of the motor 30, the U-phase current Iu and V-phase current Iv of the motor 30 from a current sensor that detects the phase currents of the U-phase and V-phase of the motor 30 can be cited. In addition, the voltage VB of the DC power supply 10 from a voltage sensor that detects the voltage of the DC power supply 10, the current of the DC power supply 10 from a current sensor that detects the current of the DC power supply 10 (hereinafter referred to as the power supply current) can be cited. Further, the ignition signal from the ignition switch, the shift position from a shift position sensor that detects the operation position of the shift lever, the accelerator opening from an accelerator pedal position sensor that detects the depression amount of the accelerator pedal, the brake pedal position from a brake pedal position sensor that detects the depression amount of the brake pedal, the vehicle speed from a vehicle speed sensor, etc. can be cited. And the control device 40 executes various controls based on the signals input from various sensors. For example, the control device 40 calculates the electrical angle and / or rotational speed of the motor 30 based on the rotational position of the motor 30 input from the rotational position sensor.

[0053] In the electric vehicle 1 configured as described above, the control device 40 sets the required torque based on the accelerator opening and the vehicle speed. The control device 40 sets this required torque as the torque command Tr of the motor 30. And the control device 40 executes the switching control of each switching element of the inverter 20 using the torque command Tr of the motor 30. When performing the switching control, the control device 40 outputs switching signals to each switching element of the inverter 20.

[0054] The control device 40 includes an inverter control unit 100 that controls the operation of the inverter 20. The inverter control unit 100 includes: a torque control unit 110, a current control unit 120, a gate signal (strobe signal) conversion unit 130, and a voltage command corrector 140. The inverter control unit 100 controls the input voltage to the motor 30.

[0055] Based on the torque command Tr of the motor 30, the torque control unit 110 generates a two-phase current command (Idtg, Iqtg). The generated two-phase current commands Idtg and Iqtg are output from the torque control unit 110 to the current control unit 120.

[0056] Based on the two-phase current commands Idtg and Iqtg input from the torque control unit 110, the current control unit 120 generates a three-phase voltage command (Vu, Vv, Vw). The generated three-phase voltage commands Vu, Vv, and Vw are output from the current control unit 120 to the gate signal conversion unit 130.

[0057] For example, in the current control unit 120, the V-phase current Iv and the W-phase current Iw are input as feedback information from the inverter 20. The current control unit 120 converts the three-phase current values into two-phase current values including the d-axis current Id and the q-axis current Iq based on the V-phase current Iv and the W-phase current Iw. The current control unit 120 generates a two-phase voltage command including the d-axis voltage Vd and the q-axis voltage Vq based on the difference between the converted two-phase current values (Id, Iq) and the two-phase current commands Idtg and Iqtg input from the torque control unit 110. Then, the current control unit 120 converts the generated two-phase voltage command (Vd, Vq) into a three-phase voltage command (Vu, Vv, Vw). In this way, the current control unit 120 generates a three-phase voltage command.

[0058] Based on the three-phase voltage commands Vu, Vv, and Vw input from the current control unit 120, the gate signal conversion unit 130 generates gate signals (switching signals) for each phase switching element of the inverter 20. The gate signal is a switching signal for switching the opening and closing of the switching element. The generated switching signals for each phase are output to the inverter 20.

[0059] By generating the switching signal of the gate signal conversion unit 130, a known method (such as PWM, etc.) can be used. For example, the gate signal conversion unit 130 is configured to be able to receive a carrier wave with a predetermined carrier frequency from the carrier wave generation unit. The gate signal conversion unit 130 compares the magnitudes of the carrier wave and the three-phase voltage commands Vu, Vv, and Vw. And, the gate signal conversion unit 130 generates the U-phase switching signals Gup, Gun, the V-phase switching signals Gvp, Gvn, and the W-phase switching signals Gwp, Gwn as switching signals whose logical states change according to the comparison result. The generated switching signals of each phase are input to the inverter 20. And, when the inverter 20 changes or maintains the driving state of each switching element to a predetermined state through the switching signals of each phase, it drives the motor 30 according to the circuit state corresponding to the driving state. The control method of this inverter 20 is a mode of PWM control. In addition, among the switching signals corresponding to each phase, the signal with the identifier called "p" is the driving signal for driving the p-side switching element in each phase of the switching element, and the signal with the identifier called "n" is the driving signal for driving the n-side switching element in each phase of the switching element.

[0060] The voltage command corrector 140 corrects the three-phase voltage commands Vu, Vv, and Vw output from the current control unit 120. The voltage command corrector 140 performs correction by adding a predetermined correction component to the three-phase voltage commands (Vu, Vv, Vw) output from the current control unit 120.

[0061] In the control device 40 configured as described above, the inverter control unit 100 switches between normal control and correction control. The normal control is control without correction by the voltage command corrector 140, and the correction control is control corrected by the voltage command corrector 140.

[0062] For example, when a ripple of a multiple component of the electrical frequency is generated in the power supply current of the DC power supply 10, the voltage command corrector 140 performs correction by adding a component (correction component) for canceling the ripple to the voltage command. That is, as an execution condition of the correction control, a case where a power supply current ripple including a multiple component of the electrical frequency is generated can be cited. The control device 40 can detect that a ripple is generated in the power supply current based on the signals input from various sensors. In addition, the multiple component of the electrical frequency includes the 6n-th component of the power supply current. As described above, as the ripple reduction control for reducing the ripple generated in the motor drive system 50, the control device 40 implements the correction control for correcting the voltage command by the voltage command corrector 140.

[0063] Regarding the configuration of the voltage command corrector 140, according to the inventors' understanding, it is clear that: if the voltage command of the inverter 20 is corrected by adding the 6n - 1st harmonic component and the 6n + 1st harmonic component, the 6nth ripple of the power supply current can be reduced. Thus, the parameter related to the input voltage of the motor 30 includes the power supply current. Further, since each harmonic component is an independent phenomenon, in the case of generating ripples of multiple components, the harmonics corresponding to each can be added and added to the voltage command. That is, harmonic superposition units of each order are added according to the harmonic component order to be reduced.

[0064] The voltage command corrector 140 includes a 6n - 1st harmonic superposition unit 141 and a 6n + 1st harmonic superposition unit 142. n is a natural number (n = 1, 2, 3,...).

[0065] The 6n - 1st harmonic superposition unit 141 corrects the voltage command by adding the 6n - 1st harmonic component. The 6n + 1st harmonic superposition unit 142 corrects the voltage command by adding the 6n + 1st harmonic component. In addition, the amplitude and phase are input to each of the 6n - 1st harmonic superposition unit 141 and the 6n + 1st harmonic superposition unit 142. Regarding the amplitude and phase, the control device 40 determines the amplitude and phase by using, for example, a method of estimating an inverter / motor model (theoretical calculation). This theoretical calculation can be an online calculation or an offline calculation. And the 6n - 1st harmonic superposition unit 141 and the 6n + 1st harmonic superposition unit 142 determine the correction value of each phase based on the input amplitude and phase. The voltage command corrector 140 outputs the determined correction value of each phase (the correction component of the voltage command).

[0066] And the correction value of each phase output from the voltage command corrector 140 is added to the three - phase voltage commands (Vu, Vv, Vw) output by the current control unit 120. Thus, when the control device 40 executes the correction control of the voltage command (ripple reduction control), the corrected three - phase voltage commands with the correction component added are input to the gate signal conversion unit 130. The gate signal conversion unit 130 generates the switching signals of each phase of the inverter 20 based on the corrected three - phase voltage commands.

[0067] Here, refer to Figures 2 to 5 the generation mechanism of the power supply current ripple is described. In addition, in this description, the side of the circuit of the motor drive system 50 closer to the motor 30 than the inverter 20 is referred to as the "AC side", and the side closer to the DC power supply 10 than the inverter 20 is referred to as the "DC side". In addition, it is clarified by the inventors' understanding Figure 2 the generation mechanism shown.

[0068] Figure 2 is a diagram for explaining the generation mechanism of the power supply current ripple. As Figure 2As shown, when observed on the AC side, it can be seen that there is almost no 6th component in the current and voltage. In other words, it can be known that the AC side current and voltage contain the 5th component and the 7th component respectively.

[0069] On the other hand, when observed on the DC side, the power contains the 6th component. The power on the DC side is based on the current and voltage on the AC side. That is to say, it is obvious that the 5th distortion and 7th distortion on the AC side become the 6th component on the DC side. Thus, according to the inventor's view, for the 6nth component on the DC side, when observed on the AC side (voltage, current, magnetic flux), it is obvious that it becomes the 6n + 1th component and the 6n - 1th component according to the properties of trigonometric functions.

[0070] Furthermore, on the DC side, the 6th component of the electrical frequency is amplified by the circuit characteristics. The ripple component is amplified by the resonance phenomenon of the smoothing capacitor and / or the inductance of the wiring. As a result, for the power supply current ripple, as Figure 3 shown, the electrical 6th component (electrical 6th cycle) dominates. Thus, according to the inventors' view, it is obvious that on the DC side, the power variation becomes the starting source of vibration, generating the 6th ripple in the power supply current. That is, it is considered that if the power variation on the DC side can be suppressed, the 6nth ripple of the power supply current can be reduced.

[0071] Figure 4 is a diagram for explaining the power variation on the DC side. As Figure 4 shown, when the 6nth ripple occurs in the power supply current, a 6nth variation (6nth power variation) occurs in the power on the DC side. This power variation on the DC side can be divided into the distortion of the voltage source component and the distortion of the current source component. Furthermore, the power on the DC side is determined by the voltage and current on the AC side. Therefore, after considering the generation mechanism as Figure 2 shown, the 6nth power variation on the DC side is determined by the 6n - 1th component and the 6n + 1th component in the voltage on the AC side and the 6n - 1th component and the 6n + 1th component in the current on the AC side. That is to say, the distortion of the voltage source component in the 6nth power variation on the DC side is caused by the 6n - 1th distortion and the 6n + 1th distortion in the voltage on the AC side. The distortion of the current source component in the 6nth power variation on the DC side is caused by the 6n - 1th distortion and the 6n + 1th distortion in the current on the AC side.

[0072] And, if the magnitudes of the distortion in the voltage source component and the current source component are compared, it can be seen that the distortion of the voltage source component is relatively small, and the distortion of the current source component is relatively large. From this result, it can be considered that the 6nth power variation on the DC side is mainly generated by the distortion of the current source component. That is, it is considered that the main reasons for generating the 6nth ripple in the power supply current are the 6n - 1th distortion and the 6n + 1th distortion in the current on the AC side.

[0073] Figure 5 This is a diagram for explaining the main reasons for the distortion of the motor current. As Figure 5 shown, on the AC side, distortion is generated in the motor electromotive force. Even when there is no distortion in the inverter voltage, distortion will still be generated in the motor electromotive force. Due to this distortion of the motor electromotive force, distortion is generated in the motor current on the AC side. In addition, through the switching control of the inverter 20, current flows back from the AC side to the DC side. And, referring to as Figure 2 , Figure 4 explained, the distortion of the power supply current in the DC side is determined by the inverter voltage and the motor current in the AC side. Therefore, as Figure 5 shown, due to the distortion of the motor current in the AC side, distortion (ripple) of the power supply current in the DC side is generated.

[0074] Therefore, as a countermeasure against the power supply current ripple, the control device 40, as Figure 6 shown, is configured to suppress the power fluctuation in the DC side. It is considered that if the 6n-th power fluctuation in the DC side can be suppressed, the 6n-th ripple of the power supply current can be reduced. Therefore, according to the inventors' opinion, a method of suppressing the power fluctuation by paying attention to the voltage source component of the power and adjusting this voltage component is considered.

[0075] Specifically, as Figure 6 shown, the control device 40 intentionally adds voltage distortion. As a result, the waveform of the voltage component is adjusted to a desired state. At this time, control is performed such that: in the power fluctuation, the fluctuation of the current source component is not adjusted while the fluctuation of the voltage source component is adjusted. And, by canceling the distortion of the current source component with the distortion of the adjusted voltage source component, the 6n-th power fluctuation in the DC side can be suppressed. In this way, by canceling the fluctuation of the current source component with the adjusted voltage source component, the power fluctuation in the DC side can be made zero.

[0076] Figure 7 This is a diagram for explaining the waveform when voltage distortion is intentionally added to the inverter voltage as a countermeasure against the power supply current ripple. As Figure 7As shown, when the motor current is distorted due to the distortion of the motor electromotive force, in order to reduce the power supply current ripple caused by the current distortion source component, the control device 40 implements correction control of the voltage command and intentionally adds distortion to the inverter voltage. The distortion component added to the inverter voltage is a component adjusted in such a way as to cancel the current distortion source component in the component of the power supply current. When distortion is added to the inverter voltage through this correction control, distortion remains in the motor current. That is, the control device 40 does not add a distortion component that completely cancels the distortion of the motor current to the inverter voltage, but adds a distortion component that becomes the voltage distortion source component and cancels the current distortion source component of the power fluctuation to the inverter voltage.

[0077] For example, when 6th-order ripple occurs in the power supply current, in the voltage command corrector 140, the 6n - 1th-order distortion superimposer 141 performs correction of adding the 5th-order distortion as a correction component to each phase voltage command, and the 6n + 1th-order distortion superimposer 142 performs correction of adding the 7th-order distortion as a correction component to each phase voltage command. In the voltage command, the 5th-order distortion component and the 7th-order distortion component are added overlapped. Therefore, the corrected voltage command contains the 5th-order distortion component and the 7th-order distortion component. And, based on this corrected voltage command, the gate signals of the switching elements of each phase are generated to control the inverter 20. The switching width of the corrected inverter voltage changes compared with the uncorrected inverter voltage. That is, when correcting the voltage command, the duty ratio is changed in such a way that the switching width changes. And, when the control device 40 implements correction control of adding the 5th-order component and the 7th-order component distortion to the voltage command, as Figure 8 shown, the 6th-order component of the power supply current can be reduced.

[0078] In this way, the inverter control unit 100 of the control device 40 controls the input voltage to the motor 30 by controlling the voltage commands of each phase. And, when a parameter related to the input voltage to the motor 30 contains a predetermined high-frequency component, the inverter control unit 100 implements correction control regarding the voltage command and performs correction of adding a component that cancels this high-frequency component to the input voltage. This high-frequency component is a 6nth-order component. That is, the ripple contains a 6th-order and / or 12th-order electrical component. Therefore, as Figure 1 shown, the voltage command corrector 140 includes a 6m - 1th-order distortion superimposer 143 and a 6m + 1th-order distortion superimposer 144. m is a natural number based on n (m = n + 1, n + 2, n + 3,...).

[0079] For example, in the case of reducing the 6th and 12th ripples of the power supply current, since n = 1 and m = 2, the 6n - 1th distortion superimposer 141 adds the distortion of the 5th component, the 6n + 1th distortion superimposer 142 adds the distortion of the 7th component, the 6m - 1th distortion superimposer 143 adds the distortion of the 11th component, and the 6m + 1th distortion superimposer 144 adds the distortion of the 13th component.

[0080] As described above, according to the embodiment, even without implementing hardware measures to cope with the electrical distortion of the inverter 20 and / or the motor 30, the 6nth ripple of the power supply current can be reduced. That is to say, for a general motor drive system 50, it can be applied without changing the hardware, and the versatility is excellent.

[0081] In addition, the electric vehicle 1 is not limited to a hybrid vehicle, and can also be an electric vehicle that uses only the motor 30 as a power source or a train (rail vehicle) equipped with the motor 30. In addition, the motor 30 can be a three-phase AC motor, and is not limited to a PM motor, and can also be an induction motor (IM).

[0082] In addition, the motor drive system 50 can include a boost converter and a smoothing capacitor. The boost converter includes a reactor, a switching element, and a diode. The smoothing capacitor is a capacitor for smoothing connected between the positive line and the negative line. In this case, the current flowing through the reactor of the boost converter and the voltage between the terminals of the smoothing capacitor are detected by various sensors. In the case of having such a smoothing capacitor, the power supply current can be reduced by the correction control of the voltage command, and thus the smoothing capacitor can be miniaturized. In addition, the control device 40 is configured to include a converter control unit that controls the drive state of the boost converter.

[0083] In addition, the method for determining the amplitude and phase of the voltage command corrector 140 is not limited to theoretical calculation. That is to say, any method such as a method of using feedback sensor values and learning or a method of plotting the results of pre-adjustment on a mapping diagram can be used as the method for determining the amplitude and phase of the correction value. For example, in the method of feedback sensor values, measure at which amplitude and phase the 6th component in the DC side becomes smaller.

[0084] In addition, in the case where the 6th ripple is generated in the power supply current, the voltage command corrector 140 can be configured to perform a correction of adding at least one of the 5th distortion and the 7th distortion to each phase voltage command. That is to say, it is not limited to the correction of adding both the 5th distortion and the 7th distortion, and the correction of adding only one of them is also possible.

[0085] In addition, the control device 40 is not limited to reducing the power supply current ripple, and may be configured to perform ripple reduction control (correction control) to reduce the motor torque ripple. The control device 40 of this modification example performs correction control of the correction voltage command as a countermeasure against the motor torque ripple. The execution condition of the correction control in this modification example is the occurrence of motor torque ripple. That is, the parameter related to the input voltage to the motor 30 includes the motor torque. The control device 40 can detect the occurrence of ripple in the motor torque based on the signals input from various sensors. In addition, the motor torque ripple includes a multiple component of the electrical frequency. This multiple component of the electrical frequency includes a 6n-th component. And when a 6n-th ripple occurs in the motor torque, the control device 40 performs correction control of the correction voltage command to reduce the motor torque ripple. Here, refer to Figures 9 to 10 A more detailed description will be given regarding the modification example.

[0086] Figure 9 It is a diagram for explaining the motor torque ripple. As Figure 9 shown, when the motor torque ripple occurs, a 6n-th ripple occurs in the motor torque. This motor 30 is an IPMSM (Interior Permanent Magnet Synchronous Motor). Therefore, the torque formula of the IPMSM is expressed by the following formula (1).

[0087] T = PΦIq + P(Lq - Ld)IdIq...(1)

[0088] In the above formula (1), P is the number of poles, Φ is the magnet magnetic flux, Iq is the q-axis current, Lq is the inductance, Ld is the inductance, and Id is the d-axis current. In addition, PΦIq represents the magnet torque. P(Lq - Ld)IdIq represents the reluctance torque. In this modification example, regarding the motor torque ripple, only the magnet torque is considered as the main cause. In addition, even when the reluctance torque is included, the idea is the same.

[0089] As shown in the above formula (1), the motor torque is determined by the motor current and the magnetic flux. And the motor torque ripple can be divided into the distortion of the current source component and the distortion of the magnetic flux source component. Therefore, as Figure 9 shown, the 6n-th ripple of the motor torque is determined by the 6n - 1-th component and 6n + 1-th component of the current and the 6n - 1-th component and 6n + 1-th component of the magnetic flux. In addition, the distortion of the motor current is generated by the distortion of the inverter voltage. That is, the 6n - 1-th distortion and 6n + 1-th distortion of the current are generated due to the distortion of the inverter voltage. Therefore, the control device 40 of the modification example, as a countermeasure against the motor torque ripple, as Figure 10As shown, corrective control for intentionally adding voltage distortion is performed in such a way as to adjust the 6n-1th component and the 6n+1th component of the current. According to this modification example, the 6nth ripple of the motor torque can be suppressed, and the torque ripple can also be made zero.

[0090] In addition, as another modification example, the control device 40 can be configured to switch between the reduction control of the power supply current ripple and the reduction control of the motor torque ripple. In the method of correcting the voltage command to reduce the power supply current ripple and the motor torque ripple, it is necessary to consider the mutual interference. Therefore, in this modification example, according to the operating point (torque, speed) of the motor 30, the control to be prioritized is switched. Here, referring to Figures 11 to 12 a more detailed description will be given of other modification examples.

[0091] Figure 11 is a mapping diagram for explaining the switching of the corrective control according to the operating point of the motor. As Figure 11 shown, when the motor torque is larger than a predetermined value, the control device 40 performs ripple reduction control. When the speed is relatively large in this high torque region, that is, when the operating point becomes Figure 11 the region A shown, the control device 40 performs the reduction control of the power supply current ripple. On the other hand, when the speed is relatively small in the high torque region, that is, when the operating point becomes Figure 11 the region B shown, the control device 40 performs the reduction control of the motor torque ripple. And when the motor torque is smaller than a predetermined value, that is, when the operating point becomes Figure 11 the region C shown, the control device 40 does not perform ripple reduction control. In addition, Figure 11 the region and the boundary shown are for example, and are not limited thereto.

[0092] Figure 12 is a flowchart showing the switching processing flow. In addition, Figure 12 the control shown is repeatedly performed by the control device 40 at a control cycle.

[0093] The control device 40 acquires the information of the speed and torque of the motor 30 (step S101). In step S101, the operating point of the motor 30 is acquired. The control device 40 calculates the speed of the motor 30 based on the rotational position of the motor 30 input from the rotational position sensor. The torque of the motor 30 can use the required torque calculated based on the accelerator opening and the vehicle speed.

[0094] The control device 40 determines whether the operating point of the motor 30 is within the region A where the reduction of the power supply current ripple is prioritized (step S102). In step S102, using the mapping diagram shown in Figure 11 and the operating point obtained according to step S101, it is determined whether to prioritize the countermeasure against the power supply current ripple.

[0095] When the operating point of the motor 30 is within the region A where the reduction of the supply current ripple is prioritized (step S102: Yes), the control device 40 performs correction control for reducing the supply current ripple (step S103). In step S103, as the control for reducing the supply current ripple, the voltage command is corrected. After the process of step S103 is implemented, this control routine ends.

[0096] When the operating point of the motor 30 is not within the region A where the reduction of the supply current ripple is prioritized (step S102: No), the control device 40 determines whether the operating point of the motor 30 is within the region B where the reduction of the motor torque ripple is prioritized (step S104). In step S104, using the Figure 11 represented mapping diagram and the operating point obtained according to step S101, it is determined whether to prioritize the countermeasures against the motor torque ripple.

[0097] When the operating point of the motor 30 is within the region B where the reduction of the motor torque ripple is prioritized (step S104: Yes), the control device 40 performs correction control for reducing the motor torque ripple (step S105). In step S105, as the control for reducing the motor torque ripple, the voltage command is corrected. After the process of step S105 is implemented, this control routine ends.

[0098] When the operating point of the motor 30 is not within the region B where the reduction of the motor torque ripple is prioritized (step S104: No), the control device 40 does not correct the voltage command and prioritizes power consumption (step S106). In step S106, using the Figure 11 represented mapping diagram and the operating point obtained according to step S101, it is implemented when the operating point is within the region C. The control device 40 performs normal control. After the process of step S106 is implemented, this control routine ends.

[0099] As shown in this other modification example, the control device 40 switches between the first correction control and the second correction control according to the operating point of the motor 30. The first correction control is a control for correcting in such a way as to cancel only the 6n-th component of the supply current among the supply current and the motor torque, and the second correction control is a control for correcting in such a way as to cancel only the 6n-th component of the motor torque. That is, it is sufficient that the parameter related to the input voltage to the motor 30 includes at least one of the supply current and the motor torque.

[0100] In addition, Figure 11The mapping diagram shown is an example, and the relationship between the operating point of the motor and the region of control implementation is not limited to this. That is, the relationship between region A where the reduction of the power supply current ripple is prioritized, region B where the reduction of the motor torque ripple is prioritized, and region C where corrective control is not implemented is not limited to Figure 11 the example shown.

[0101] In addition, in the prior art, although the ripple of the switching frequency component can be reduced by measures to cope with the power supply voltage ripple, measures to cope with harmonic iron loss have not been considered, so the multiple component of the electrical frequency cannot be reduced, and there is room for improvement. In the motor drive system 50, due to the distortion of the inverter voltage and / or the current and / or magnetic flux of the motor 30, sometimes a 6nth-order distortion is generated in the magnetic flux, and harmonic iron loss caused thereby is generated. Therefore, as a further modification example, the control device 40 performs corrective control to correct the voltage command as a measure to cope with harmonic iron loss. The execution condition of the corrective control in this modification example is the case where distortion occurs in the magnetic flux. That is, the parameter related to the input voltage of the motor 30 includes the magnetic flux. The control device 40 can detect the occurrence of distortion in the magnetic flux based on the signals input from various sensors. In addition, the distortion of the magnetic flux includes a multiple component of the electrical frequency. This multiple component of the electrical frequency includes a 6nth-order component. And when a 6nth-order component distortion occurs in the magnetic flux, the control device 40 performs corrective control to correct the voltage command in order to reduce the distortion of the magnetic flux. Thus, the control device 40 can also be configured to perform distortion reduction control (corrective control) for reducing the distortion of the 6-fold component of the magnetic flux, not limited to the reduction of the power supply current ripple or the motor torque ripple. Here, refer to Figures 13 to 14 for a more detailed description of further modification examples.

[0102] Figure 13 is a diagram for explaining the distortion of the magnetic flux. As Figure 13 shown, in the case of generating harmonic iron loss, a 6nth-order distortion occurs in the magnetic flux on the DC side. The magnetic flux on the DC side is determined by the current magnetic flux on the AC side and the magnet magnetic flux. And the distortion of the magnetic flux on the DC side can be divided into the distortion of the component derived from the current magnetic flux and the distortion of the component derived from the magnet magnetic flux. Therefore, considering the Figure 13 shown generation mechanism, the 6nth-order distortion of the magnetic flux on the DC side is determined by the 6n - 1th-order component and the 6n + 1th-order component in the current magnetic flux on the AC side and the 6n - 1th-order component and the 6n + 1th-order component in the magnet magnetic flux on the AC side.

[0103] The distortion of the current magnetic flux on the AC side is generated by the distortion of the inverter voltage. That is, the 6n - 1th distortion and the 6n + 1th distortion of the current magnetic flux on the AC side are caused by the distortion of the inverter voltage. In addition, the distortion of the magnet magnetic flux on the AC side is due to the configuration of the magnets or the unevenness of the magnets, that is, it is determined by the structure of the motor 30. Therefore, as a countermeasure against harmonic iron loss, the control device 40, as Figure 14 shown, is configured to intentionally add voltage distortion to suppress the 6nth distortion of the magnetic flux on the DC side.

[0104] Specifically, the control device 40 performs correction control to intentionally add voltage distortion in such a way as to adjust the 6n - 1th component and the 6n + 1th component of the current magnetic flux on the AC side. At this time, control is performed such that: among the distortions of the magnetic flux, the distortion of the component derived from the magnet magnetic flux is not adjusted while the distortion of the component derived from the current magnetic flux is adjusted. And by canceling out the distortion of the component derived from the magnet magnetic flux and the adjusted distortion of the component derived from the current magnetic flux, the 6nth distortion of the magnetic flux on the DC side can be suppressed. According to this modification example, by canceling out the distortion of the component derived from the magnet magnetic flux with the adjusted component derived from the current magnetic flux on the AC side, the distortion of the magnetic flux on the DC side can be made zero. Thus, by suppressing the distortion of the magnetic flux on the DC side, harmonic iron loss can be reduced. Thereby, harmonic iron loss can be reduced and the efficiency (system efficiency) of the motor drive system 50 can be improved. That is, even without implementing hardware measures to cope with the electrical distortion of the inverter 20 and / or the motor 30, harmonic iron loss can be reduced.

[0105] In addition, as yet another further modification example, the control device 40 may be configured to switch between implementing control to reduce magnetic flux distortion and normal control. In the method of correcting the voltage command to reduce the power supply current ripple, the motor torque ripple, and the magnetic flux distortion, it is necessary to consider the mutual interference. Therefore, in this modification example, according to the operating point (torque, speed) of the motor 30, the control to be prioritized is switched. Here, referring to Figure 15 , a yet another further modification example will be described in more detail.

[0106] Figure 15 is a mapping diagram for explaining the implementation of correction control regarding the magnetic flux according to the operating point of the motor. As Figure 15 shown, when the motor torque is smaller than the second predetermined value and the motor speed is smaller than the third predetermined value, the control device 40 implements control to reduce magnetic flux distortion. That is, when the motor 30 is in the low torque region and the low rotation region, that is, when the operating point becomes Figure 15 the region D shown, the control device 40 implements control to reduce magnetic flux distortion. And when the operating point of the motor 30 becomes Figure 15When in the area C shown, the control device 40 implements normal control without correction. The normal control is a control that prioritizes power consumption over the reduction of ripple and distortion. Thus, the control device 40 switches between the third correction control and the normal control according to the operating point of the motor 30. The third correction control is a control that corrects in such a way as to cancel only the 6n-th component of the magnetic flux on the DC side, and the normal control is a control without correction. Thereby, according to the state of the motor 30, it is possible to take into account reducing harmonic iron loss by implementing the third correction control and ensuring efficiency by implementing the normal control.

[0107] Furthermore, in this modification, the control device 40 can switch between the first correction control, the second correction control, the third correction control, and the normal control according to the operating point of the motor 30. The first correction control is a control that corrects in such a way as to cancel only the 6n-th component of the power supply current among the power supply current, the motor torque, and the magnetic flux. The second correction control is a control that corrects in such a way as to cancel only the 6n-th component of the motor torque among the power supply current, the motor torque, and the magnetic flux. The third correction control is a control that corrects in such a way as to cancel only the 6n-th component of the magnetic flux among the power supply current, the motor torque, and the magnetic flux. The normal control is a control without correction. That is, the parameter related to the input voltage of the motor 30 may include at least one of the power supply current, the motor torque, and the magnetic flux on the DC side. In this case, in the high torque region, when the rotational speed is relatively large, that is, when the operating point becomes Figure 15 When in the area A shown, the control device 40 implements control to reduce the power supply current ripple. When the rotational speed is relatively small, that is, when the operating point becomes Figure 15 When in the area B shown, the control device 40 implements control to reduce the motor torque ripple. Thereby, it is possible to avoid mutual interference between the control to reduce the power supply current ripple, the control to reduce the motor torque ripple, and the control to reduce harmonic iron loss. In addition, Figure 15 The shown area and the boundary are taken as an example, and are not limited thereto.

[0108] Reference Numeral Explanation

[0109] 1 Electric vehicle; 10 DC power supply; 20 Inverter; 30 Motor; 40 Control device; 50 Motor drive system; 100 Inverter control unit; 110 Torque control unit; 120 Current control unit; 130 Gate signal conversion unit; 140 Voltage command corrector; 141 6n - 1-th distortion superposer; 142 6n + 1-th distortion superposer; 143 6m - 1-th distortion superposer; 144 6m + 1-th distortion superposer.

Claims

1. A control device for an electric vehicle, the electric vehicle comprising: A DC power supply; A three-phase AC motor; An inverter that converts DC power supplied from the DC power supply into AC power and outputs it to the three-phase AC motor; and A control unit that controls the inverter and controls the input voltage to the three-phase AC motor; The control device is characterized in that When the parameter related to the input voltage includes a predetermined high-frequency component, the control unit performs correction by adding a component that cancels the high-frequency component to the input voltage, and controls the three-phase AC motor based on the corrected input voltage. The parameter includes at least one of the power supply current and the motor torque. The high-frequency component is a 6n-th component. The control device switches between a first correction control and a second correction control according to the operating point of the three-phase AC motor. The first correction control is a control that performs the correction in a manner that only cancels the 6n-th component of the power supply current among the power supply current and the motor torque, and the second correction control is a control that performs the correction in a manner that only cancels the 6n-th component of the motor torque among the power supply current and the motor torque.

2. The control device for an electric vehicle according to claim 1, Characterized in that The component that cancels the high-frequency component includes at least one of a 6n - 1-th component and a 6n + 1-th component.

Images