Electric motor control method and electric motor control device

Abstract

To provide a motor control method and a motor control device that can appropriately perform switching between current vector control and voltage phase control both in normal operation and at a sudden change in load.SOLUTION: A motor control method controls a motor while switching between a first control mode (current vector control) for feeding back a current value of a motor 11 to a current target value that is a target value of a current supplied to the motor 11, thereby calculating a voltage command value for controlling the motor 11, and a second control mode (voltage phase control) for feeding back the current value or a parameter calculated based on the current value to a command value related to the phase of a voltage supplied to the motor, thereby calculating the voltage command value. A delay time is set to the switching between the first control mode and the second control mode. The delay time for the switching from the second control mode to the first control mode is changed according to a power supply voltage Vdc.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method and a device for controlling an electric motor. [Background technology]

[0002] Patent Document 1 discloses a motor control method that executes either current vector control or voltage phase control depending on the operating state of the motor. In this motor control method, the timing for switching between current vector control and voltage phase control is determined based on the current value of the motor or a state quantity calculated based on the current value of the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 106729 Summary of the Invention [Problem to be solved by the invention]

[0004] Both current vector control and voltage phase control are control configurations that adjust the voltage supplied to the motor by feeding back the motor current value and other parameters that represent the motor's state (hereinafter, these are collectively referred to as the motor's state quantities, or simply as state quantities). However, the state quantities inevitably contain harmonics. This is due to, for example, the magnetic characteristics of the motor and the error characteristics of sensors, i.e., hardware characteristics and detection errors. Therefore, when the motor's state quantities are used to determine the timing of switching between current vector control and voltage phase control, the harmonics contained in the state quantities are reduced or removed by averaging processing using a low-pass filter or the like. This is to suppress the steps and resulting shocks that occur when switching between controls.

[0005] In normal operating conditions where the state quantities change relatively slowly, the time constant of the low-pass filter must be set relatively long (large) to sufficiently reduce the harmonics contained in the state quantities. However, if the time constant of the low-pass filter is set long, when the state quantities change suddenly due to a sudden change in the load on the motor (hereinafter simply referred to as a sudden load change), the establishment of the control switching decision is delayed, resulting in an unintended current increase in the control. As a result, the surge voltage in the semiconductor switching elements included in the inverter increases, and the voltage applied to the semiconductor switching elements may exceed the upper limit of the withstand voltage of the semiconductor switching elements.

[0006] Conversely, to prevent a delay in control switching when a state quantity changes suddenly due to a sudden change in load, etc., it is necessary to set the time constant of the low-pass filter relatively short. However, if the time constant of the low-pass filter is set short, chattering of control switching may occur in normal operating conditions, which may result in unexpected vibrations.

[0007] In particular, since voltage phase control is a nonlinear control system, the loop transfer characteristics consisting of the control system and the motor change depending on the operating state of the motor, making it difficult to design a low-pass filter that can solve both the problems that occur during sudden load changes and during normal operation.

[0008] The present invention aims to provide a motor control method and a motor control device that can appropriately switch between current vector control and voltage phase control so as to prevent the above-mentioned problems from occurring both during normal operation and when the load suddenly changes. [Means for solving the problem]

[0009] In one aspect of the present invention, there is provided a first control mode (current vector control) in which a voltage command value for controlling the motor is calculated by feeding back the current value of the motor to a current target value, which is a target value of the current supplied to the motor; Voltage phase command value, which is a command value for the voltage phase , the current value or the value calculated based on the current value Torque Deviation In this motor control method, a delay time is set for switching between the first control mode and the second control mode. The delay time for switching from the second control mode to the first control mode is The higher the power supply voltage, the shorter the time. The lower the power supply voltage, the longer the time. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a motor control method and a motor control device that can appropriately switch between current vector control and voltage phase control both during normal operation and when a sudden load change occurs. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of an electric motor control device. [Figure 2] FIG. 2 is a block diagram showing the configuration of the control calculation unit. [Figure 3] FIG. 3 is a block diagram showing the configuration of the current vector control unit. [Figure 4] FIG. 4 is a block diagram showing the configuration of the voltage phase control unit. [Figure 5] FIG. 5 is a graph showing an example of the relationship between voltage phase and torque. [Figure 6] FIG. 6 is a block diagram showing the configuration of the control mode switching unit. [Figure 7] FIG. 7 is a block diagram showing a specific configuration of the control mode determination unit. [Figure 8] FIG. 8 is an explanatory diagram showing the relationship between the power supply voltage and the control mode switching line. [Figure 9] FIG. 9 is a graph showing the input / output static characteristics of the motor under voltage phase control. [Figure 10] FIG. 10 is a graph schematically showing the characteristics of a semiconductor switching element. [Figure 11]FIG. 11 is a flowchart showing the operation of switching the control mode by the motor control device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] [First embodiment] Fig. 1 is a block diagram showing a schematic configuration of an electric motor control device 100. As shown in Fig. 1, the electric motor control device 100 drives an electric motor 11 with power supplied from a power source 10 and controls its operating state. The power source 10, the electric motor 11, and the electric motor control device 100 are mounted as drive sources in a vehicle such as an electric vehicle or a hybrid vehicle, for example.

[0014] The power supply 10 is a source of power supply to the electric motor 11 and other components of the vehicle, etc. The power supply 10 is directly a secondary battery such as a lithium-ion battery. Therefore, the power supply 10 can be charged by an external power source, regenerative braking force, etc. The power supply 10 may include a device such as a fuel cell that generates power to charge the secondary battery.

[0015] In this embodiment, the power supply 10 is a DC power supply. That is, the voltage output by the power supply 10 is a direct current voltage (hereinafter referred to as a DC voltage), the current output by the power supply 10 is an alternating current (DC current), and the power output by the power supply 10 is direct current power (DC power).

[0016] In this embodiment, the DC voltage output by the power supply 10 is detected as appropriate by a voltage detector 21. The motor control device 100 and the like then calculate the detected DC voltage (hereinafter referred to as the power supply voltage V dc It is important to note that the power supply voltage V dcHowever, this may vary to a certain extent depending on the actual and specific state of the power supply 10, such as the SOC (State Of Charge) and SOH (State Of Health) of the power supply 10. For this reason, the motor control device 100 dc The operating state of the electric motor 11 is controlled in accordance with the detected voltage.

[0017] The electric motor 11 is, for example, an IPM (Interior Permanent Magnet) type three-phase synchronous motor. In this embodiment, the electric motor 11 is an IPM type three-phase synchronous motor and has windings of three phases: U phase, V phase, and W phase. Note that other types of electric motors can also be controlled by the electric motor control device 100 as long as they can be driven by so-called voltage vector control and voltage phase control.

[0018] The motor control device 100 is configured by a control calculation unit 12, a coordinate conversion unit 13, a PWM conversion unit 14, an inverter 15 (INV.), a coordinate conversion unit 16, a rotation speed calculation unit 17, and the like.

[0019] The control calculation unit 12 calculates the torque command value T * In order to make the electric motor 11 output a torque T corresponding to * Specifically, the control calculation unit 12 calculates a command value for the voltage to be supplied to the electric motor 11 based on the torque command value T * , d-axis current i d , q-axis current i q , power supply voltage V dc , and the rotation speed N, the d-axis voltage command value V d-fin * and q-axis voltage command value V q-fin * Calculate the following.

[0020] Torque command value T * is a command related to the torque T to be outputted from the electric motor 11, and is determined in advance by, for example, a higher-level controller (computer) (not shown) in accordance with the operation of the vehicle by the driver.

[0021] d-axis current i dand q-axis current i q is a current value obtained by converting the detected value of the current flowing through the electric motor 11 into a current in the dq-axis coordinate system that rotates together with the rotor of the electric motor 11. The control calculation unit 12 receives the d-axis current i d and q-axis current i q In the following, the d-axis current i d and q-axis current i q Putting these together, the dq axis current i d ,i q That's what they say.

[0022] Power supply voltage V dc is obtained from the voltage detector 21. The power supply voltage V dc As described above, since the power supply voltage V changes depending on the SOC of the power supply 10, the control calculation unit 12 dc By appropriately obtaining the power supply voltage V dc The d-axis voltage command value V d-fin * and q-axis voltage command value V q-fin * Calculate the following.

[0023] The rotation speed N [rpm] is a parameter that represents the rotation state of the electric motor 11, more specifically, the rotation speed, and is calculated based on the electrical angle θ [deg] of the electric motor 11. The control calculation unit 12 acquires the rotation speed N from the rotation speed calculation unit 17.

[0024] d-axis voltage command value V d-fin * and q-axis voltage command value V q-fin * is the torque command value T * The d-axis voltage command value V is a command value of the voltage to be supplied to the electric motor 11 in order to output a torque T corresponding to the d-fin * and q-axis voltage command value V q-fin * is the voltage command value in the dq-axis coordinate system. In the following, the d-axis voltage command value V d-fin * and q-axis voltage command value V q-fin * The dq-axis voltage command value V d-fin* ,V q-fin * The control calculation unit 12 calculates the dq-axis voltage command value V d-fin * ,V q-fin * is output to the coordinate conversion unit 13.

[0025] The control calculation unit 12 configured as above has two control modes, a first control mode and a second control mode, for controlling the electric motor 11. The first control mode is a mode in which the electric motor 11 is controlled by current vector control. The second control mode is a mode in which the electric motor 11 is controlled by voltage phase control. The first control mode and the second control mode can be switched appropriately. Therefore, the d-axis voltage command value V d-fin * and q-axis voltage command value V q-fin * is calculated by current vector control in the first control mode, or by voltage phase control in the second control mode. The specific configuration of the control calculation unit 12 that switches between these control modes will be described in detail later.

[0026] The coordinate conversion unit 13 converts the dq-axis voltage command value V d-fin * ,V q-fin * into voltage command values ​​for the UV and W phases. That is, the coordinate conversion unit 13 converts the dq-axis voltage command value V d-fin * ,V q-fin * Based on this, the U-phase voltage command value V u * ,V-phase voltage command value V v * , and W-phase voltage command value V w * In the following, the U-phase voltage command value V u * ,V-phase voltage command value V v * , and W-phase voltage command value V w * The three-phase voltage command value V u * ,Vv * ,V w * Specifically, the coordinate conversion unit 13 calculates the three-phase voltage command value V in accordance with the electrical angle θ of the electric motor 11 based on the following formula (1): u * ,V v * ,V w * is output to the PWM conversion unit 14. The electrical angle θ is detected by the electrical angle detector 22.

[0027]

number

[0028] The PWM conversion unit 14 converts the power supply voltage V dc Based on this, the three-phase voltage command value V u * ,V v * ,V w * is converted into a PWM (Pulse Width Modulation) signal D, which is a drive signal for the semiconductor switching element 23 (sw) that constitutes the inverter 15. uu * ~D wl * Converts to PWM signal D uu * ~D wl * The first subscripts u, v, and w represent the UVW phases, respectively, and the second subscripts u and l represent the drive signals for the upper arm (u) and the lower arm (l) of the semiconductor switching element of each phase. uu * ~D wl * is output to the inverter 15.

[0029] The inverter 15 is configured using a plurality of semiconductor switching elements 23. The inverter 15 receives a PWM signal D uu * ~D wl *By driving these semiconductor switching elements 23 based on the dc AC voltage V u ,V v ,V w Then, the inverter 15 converts the AC voltage V u ,V v ,V w are supplied to the U, V and W phases of the electric motor 11. As a result, the electric motor 11 operates in response to the torque command value T * The motor is driven to output a torque T according to the

[0030] The semiconductor switching element 23 that constitutes the inverter 15 is a physical circuit element. Therefore, the voltage V sw and current I sw In the following, the voltage V input or output by the semiconductor switching element 23 is sw and current I sw The upper limit values ​​of the upper limit voltage V UL and upper limit current I UL In principle, the semiconductor switching element 23 is dc However, when the current vector control and the voltage vector control are switched, the voltage V of the semiconductor switching element 23 changes due to this switching. sw and current I sw In the following, a surge in the voltage of the semiconductor switching element 23 is referred to as a surge voltage, and the magnitude of the surge voltage is referred to as a surge width W. M Surge width W M is the power supply voltage V dc The upper limit voltage V UL and the power supply voltage V dc difference (V UL -V dc ) is the surge voltage (surge width W M ), which will be referred to below as the surge margin V M That's what they say.

[0031] The coordinate conversion unit 16 converts the detected value of the current of the electric motor 11 into the dq axis current i d ,i q In this embodiment, the coordinate conversion unit 16 converts the U-phase current i u and V-phase current i v The dq axis current i d ,i q The coordinate conversion unit 16 converts the dq-axis current i d ,i q to the control calculation unit 12. Specifically, the coordinate conversion unit 16 calculates the U-phase current i u and V-phase current i v The dq axis current i d ,i q Convert to.

[0032]

number

[0033] U phase current i u and V-phase current i v is detected by the current detector 24. The current detector 24 may detect currents of at least two of the three phases. When the current detector 24 is configured to detect three-phase currents, the coordinate conversion unit 16 calculates the dq-axis current i d ,i q Calculate the following.

[0034] The rotation speed calculation unit 17 calculates the rotation speed N of the electric motor 11 based on the amount of change per unit time of the electrical angle θ. The rotation speed calculation unit 17 outputs the rotation speed N to the control calculation unit 12.

[0035] In the motor control device 100 configured as described above, for example, the control calculation unit 12, the coordinate conversion unit 13, the PWM conversion unit 14, the coordinate conversion unit 16, and the rotation speed calculation unit 17 are configured by one or more computers. That is, one or more computers are programmed to function as the control calculation unit 12, the coordinate conversion unit 13, the PWM conversion unit 14, the coordinate conversion unit 16, and the rotation speed calculation unit 17. On the other hand, the inverter 15, the semiconductor switching elements 23, the voltage detector 21, the electrical angle detector 22, and the current detector 24 are circuit devices or the like that cooperate with the above-mentioned computers.

[0036] [Configuration of control calculation section] Fig. 2 is a block diagram showing the configuration of the control calculation unit 12. As shown in Fig. 2, the control calculation unit 12 includes a current vector control unit 26 (first control unit), a voltage phase control unit 27 (second control unit), a control mode switching unit 28, and a delay time setting unit 29.

[0037] The current vector control unit 26 controls the d-axis voltage command value and the q-axis voltage command value (hereinafter referred to as the dq-axis voltage command value V di-fin * ,V qi-fin * The current vector control is a control in which the current value of the electric motor 11 is fed back to a current target value, which is a target value of the current supplied to the electric motor 11. In this embodiment, the current vector control unit 26 calculates the d-axis current target value i d * and q-axis current target value i q * (Hereinafter, the dq axis current target value i d * ,i q * ) and calculate the dq axis current target value i d * ,i q * In response to this, the current value of the motor 11 (dq axis current i d ,i q ) as feedback.

[0038] Specifically, the current vector control unit 26 calculates the torque command value T * , rotation speed N, power supply voltage V dc , and dq axis current i d ,i q Based on this, the dq-axis voltage command V di-fin * ,V qi-fin * Calculates the dq-axis voltage command V of the current vector control. di-fin * ,V qi-fin * The specific configuration for calculating the above will be described in detail later.

[0039] The voltage phase control unit 27 controls the d-axis voltage command value and the q-axis voltage command value (hereinafter referred to as the dq-axis voltage command value V dv-fin * ,V qv-fin * The voltage phase control is a control in which the current value of the motor 11 or a parameter calculated from the current value of the motor 11 is fed back to the phase of the voltage supplied to the motor 11 (hereinafter referred to as voltage phase α). In this embodiment, a target value or command value for the voltage phase α (hereinafter referred to as voltage phase command value α * ) and calculate the voltage phase command value α * The "current value of the motor 11 or a parameter calculated from the current value of the motor 11" is, for example, the dq-axis current i d ,i q , or dq axis current i d ,i q In the voltage phase control of this embodiment, for example, the dq-axis current i d ,i q The torque T of the electric motor 11 is estimated using the above. Then, the estimated value (hereinafter referred to as the torque estimated value T est ) is the voltage phase command value α * By feeding back to the d ,i q is the voltage phase command value α * is fed back to.

[0040] Specifically, the voltage phase control unit 27 calculates the torque command value T * , rotation speed N, power supply voltage V dc , and dq axis current i d ,i q Based on this, the dq-axis voltage command value V dv-fin * ,V qv-fin * Also, the dq-axis voltage command value V dv-fin * ,V qv-fin * A part or all of the control gains used by the voltage phase control unit 27 when calculating the dq-axis voltage command value V dv-fin * ,V qv-fin * The specific configuration for calculating the above will be described in detail later.

[0041] The control mode switching unit 28 switches or maintains the control mode of the electric motor 11. Specifically, the control mode switching unit 28 dc , and the time constant τ set by the delay time setting unit 29 va and switching prohibition period t mask When the first control mode is selected, the control mode switching unit 28 selects the dq-axis voltage command value V di-fin * ,V qi-fin * The final dq-axis voltage command value V d-fin * ,V q-fin * On the other hand, when the second control mode is selected, the control mode switching unit 28 outputs the dq-axis voltage command value V dv-fin * ,V qv-fin * The final dq-axis voltage command value V d-fin * ,V q-fin * to the coordinate conversion unit 13. The control mode switching unit 28 also outputs a mode selection signal S indicating whether the selected control mode is the first control mode or the second control mode. mode to the delay time setting unit 29. The specific configuration of the control mode switching unit 28 will be described in detail later.

[0042] The delay time setting unit 29 receives the mode selection signal S mode and the variable power supply voltage V dc In particular, the delay time setting unit 29 sets a variable delay time for at least switching from the second control mode to the first control mode. Specifically, the delay time setting unit 29 sets a variable time constant τ va The delay time can be set by setting or changing the control mode switching inhibition period t mask In this embodiment, the delay time setting unit 29 can set or change the power supply voltage V dc Based on the time constant τ va and switching prohibition period t mask However, the delay time setting unit 29 sets or changes the time constant τ va or switching prohibition period t mask The delay time may be set by setting or changing either one of the above.

[0043] Furthermore, delay time setting unit 29 sets or changes some or all of the control gains used by voltage phase control unit 27 to assist in setting or changing the variable delay time. This makes it easier to set the delay time within a range that does not exceed a practically allowable value. In this embodiment, delay time setting unit 29 sets or changes some or all of the control gains used by voltage phase control unit 27, such as proportional gain K φp and integral gain K φi Set or change (see Figure 4).

[0044] In this embodiment, the delay time setting unit 29 sets a delay time for both switching from the first control mode to the second control mode and switching from the second control mode to the first control mode. dc The delay time is changed depending on the power supply voltage V when switching from the second control mode (voltage phase control) to the first mode (current vector control). That is, when switching from the first control mode (current vector control) to the second control mode (voltage phase control), the delay time is changed depending on the power supply voltage V dc The specific setting of the delay time will be described in detail later.

[0045] [Configuration of current vector control unit] Fig. 3 is a block diagram showing the configuration of current vector control unit 26. As shown in Fig. 3, current vector control unit 26 includes a non-interference voltage calculation unit 31, an averaging processing unit 32, a current target value calculation unit 33, a deviation calculation unit 34, a PI control unit 35, and an addition unit 36.

[0046] The non-interference voltage calculation unit 31 calculates the torque command value T * , rotation speed N, and power supply voltage V dc Based on this, the non-interfering voltage V d-dcpl * Calculate the non-interfering voltage V d-dcpl * is a target value of the voltage to be supplied to the d-axis, and is a voltage value obtained by reducing or eliminating the interference voltage that interferes between the d-axis and the q-axis. * , rotation speed N, and power supply voltage V dc and the non-interfering voltage V d-dcpl * The decoupling voltage calculation unit 31 stores in advance a decoupling voltage table (look-up table) in which the decoupling voltages V and V correspond to each other based on experiments, simulations, etc. Therefore, the decoupling voltage calculation unit 31 can calculate the decoupling voltage V by referring to the decoupling voltage table. d-dcpl * The decoupling voltage calculation unit 31 calculates the decoupling voltage V d-dcpl *is output to the averaging processor 32.

[0047] The averaging processor 32 calculates the non-interfering voltage V d-dcpl * By averaging the voltages, the averaged non-interfering voltage V d-dcpl-flt * The averaging processor 32 is configured with a filter such as a low-pass filter (LPF), a band-pass filter, a moving average filter, a Gaussian filter, or a median filter. In this embodiment, the averaging processor 32 is a low-pass filter. The averaged non-interference voltage V d-dcpl-flt * is output to the adder 36.

[0048] The current target value calculation unit 33 calculates the torque command value T * , rotation speed N, and power supply voltage V dc Based on this, the d-axis current target value i d * The current target value calculation unit 33 calculates, for example, the torque command value T * , rotation speed N, and power supply voltage V dc and the d-axis current target value i d * (and the q-axis current target value i q * ) and the d-axis current target value i d * The d-axis current target value i d * is output to the deviation calculation unit 34.

[0049] The deviation calculation unit 34 calculates the d-axis current target value i d * and the detected value of the d-axis current i d and the d-axis current deviation i d-err In this embodiment, the deviation calculation unit 34 calculates the d-axis current target value i d * From d-axis current i dThe resulting d-axis current deviation i d-err (=i d * -i d ) is output to the PI control unit 35.

[0050] The PI control unit 35 controls the d-axis current i d is the d-axis current target value i d * Specifically, the PI control unit 35 performs current feedback processing to adjust the d-axis voltage command value so that the d-axis current deviation i d-err Based on this, the current feedback d-axis voltage command value V di ' is calculated. "s" in formula (3) is the Laplace operator, and "K dp " is the d-axis proportional gain, and "K di " is the d-axis integral gain. In this embodiment, the d-axis proportional gain K dq and d-axis integral gain K di is a fixed value determined in advance by experiment, simulation, etc. The PI control unit 35 calculates the current feedback d-axis voltage command value V di ' is output to the adder 36.

[0051]

number

[0052] The adder 36 calculates the averaged non-interfering voltage V as shown in the following formula (4): d-dcpl-flt * and the current feedback d-axis voltage command value V di By adding ', the d-axis voltage command value V di-fin * The d-axis voltage command value V di-fin * is input to the control mode switching unit 28 as described above.

[0053]

number

[0054] 3 shows the configuration of the current vector control unit 26 related to the d-axis, the current vector control unit 26 has the same configuration as above, and controls the q-axis voltage command value V dq-fin * The description of the configuration of the current vector control unit 26 relating to the q axis will be omitted.

[0055] [Configuration of voltage phase control section] Fig. 4 is a block diagram showing the configuration of voltage phase control unit 27. As shown in Fig. 4, voltage phase control unit 27 includes a voltage norm calculation unit 41, a voltage phase calculation unit 42, a first feedback system 43, and a second feedback system 44.

[0056] The voltage norm calculation unit 41 calculates the voltage V dc Based on the voltage norm V a The command value by feedforward control for a-ff Specifically, the voltage norm calculation unit 41 calculates the feedforward voltage norm command value V a-ff Calculates the feedforward voltage norm command value V a-ff is input to the adder 71 and the voltage phase calculator 42, and the voltage norm V a The voltage norm command value V a * is used in the calculation of

[0057]

number

[0058] In addition, "M * " is the reference modulation factor. Reference modulation factor M * is the reference value of the modulation factor M to be realized by voltage phase control. It is a predetermined modulation factor that is determined in advance as the reference of the modulation factor M in voltage phase control. The modulation factor M is calculated by multiplying the power supply voltage V dcThe correlation voltage is, for example, the voltage between the U and V phases of the motor 11 (V u -V v )

[0059] When the modulation factor M is 1.0 or less, the voltage phase control is in a normal control region (normal modulation region) where the fundamental component of the correlation voltage can be converted into a quasi-sine wave by PWM control. When the modulation factor M exceeds 1.0, the voltage phase control operates in an overmodulation control region (so-called overmodulation region), and even if a quasi-sine wave is generated, the waveform shape of the correlation voltage is partially limited at its peaks and troughs. When the modulation factor M is approximately 1.1, the voltage phase control operates in a control region (so-called square wave region) where the fundamental component of the correlation voltage is substantially equivalent to a square wave. Voltage phase control has the advantage of expanding the range of operating states (operating points) of the motor 11, particularly by controlling in the overmodulation region and square wave region (so-called flux-weakening region).

[0060] The voltage phase calculation unit 42 calculates the feedforward voltage norm command value V a-ff , rotation speed N, and torque command value T * Based on this, the command value by feedforward control for the voltage phase α (hereinafter referred to as the feedforward voltage phase command value α ff The voltage phase calculation unit 42 calculates the feedforward voltage norm command value V a-ff , rotation speed N, and torque command value T * and the feedforward voltage phase command value α ff The voltage phase calculation unit 42 stores in advance a voltage phase table (look-up table) that associates the voltages and the phases based on experiments, simulations, etc. Therefore, the voltage phase calculation unit 42 references this voltage phase table to calculate the feedforward voltage phase command value α ff The feedforward voltage phase command value α ff is input to the adder 73, and the final voltage phase command value α * is used in the calculation of

[0061] The first feedback system 43 is a voltage norm V a In this embodiment, the first feedback system 43 is a system that feeds back the current value of the electric motor 11 or a parameter calculated from the current value of the electric motor 11. In this embodiment, the first feedback system 43 feeds back the dq-axis current i d ,i q The parameters related to the magnetic flux norm φ are calculated from the a * Feedback to.

[0062] Specifically, the first feedback system 43 includes a current target value calculation unit 51, a magnetic flux calculation unit 52, a reference magnetic flux norm calculation unit 53, a magnetic flux estimation unit 54, a deviation calculation unit 55, and a PI control unit 56.

[0063] The current target value calculation unit 51 calculates the torque command value T * , rotation speed N, and power supply voltage V dc Based on this, the dq axis current target value i d * ,i q * The current target value calculation unit 51 calculates, for example, the torque command value T * , rotation speed N, and power supply voltage V dc and the dq axis current target value i d * ,i q * The current target value calculation unit 51 stores in advance a current target value table (look-up table) in which the d-axis current target value i and the q-axis current target value i are associated with each other through experiments, simulations, etc. Therefore, the current target value calculation unit 51 references this current target value table to calculate the d-axis current target value i d * ,i q * The current target value calculation unit 51 calculates the dq-axis current target value i d * ,i q * is input to the magnetic flux calculation unit 52.

[0064] The magnetic flux calculation unit 52 calculates the dq-axis current target value i d* ,i q * The magnetic flux norm command value φ0 is a command value for the norm of the composite magnetic flux (magnetic flux norm φ) of the magnet magnetic flux and the current magnetic flux. Specifically, the magnetic flux calculation unit 52 calculates the magnetic flux norm command value φ0 based on the following formula (6). In formula (6), "φ a " is the number of winding interlinkage magnetic fluxes, and "L d " is the d-axis inductance, and "L q " is the q-axis inductance. These are constants that are determined in advance for the specific electric motor 11. The same applies to equation (7) described later. The magnetic flux norm command value φ0 is input to the reference magnetic flux norm calculation unit 53.

[0065]

number

[0066] The reference magnetic flux norm calculation unit 53 calculates the reference magnetic flux norm φ based on the magnetic flux norm command value φ0. 0-ref Calculate the reference flux norm φ 0-ref represents the target response of the magnetic flux norm φ. The reference magnetic flux norm calculation unit 53 is configured by a filter such as a low-pass filter (LPF), a band-pass filter, a moving average filter, a Gaussian filter, or a median filter. In this embodiment, the reference magnetic flux norm calculation unit 53 is a low-pass filter. The reference magnetic flux norm φ 0-ref is input to the deviation calculation unit 55.

[0067] The magnetic flux estimation unit 54 estimates the dq-axis current i d ,i q Based on this, the flux norm estimate φ is calculated as 0-est Specifically, the magnetic flux estimation unit 54 calculates the magnetic flux norm estimation value φ based on the following equation (7). 0-est Calculate the flux norm estimate φ 0-est is input to the deviation calculation unit 55.

[0068]

number

[0069] The deviation calculation unit 55 calculates the magnetic flux norm command value φ0 and the magnetic flux norm estimated value φ 0-est The magnetic flux norm deviation φ 0-err In this embodiment, the deviation calculation unit 55 calculates the magnetic flux norm estimated value φ from the magnetic flux norm command value φ. 0-est By subtracting the flux norm deviation φ 0-err Calculate the magnetic flux norm deviation φ 0-err is input to the PI control unit 56.

[0070] The PI control section 56 controls the voltage norm V a is the voltage norm command value V a * Specifically, the PI control unit 56 calculates the magnetic flux norm deviation φ by the following equation (8): 0-err (=φ 0-ref -φ 0-est ) based on the feedback voltage norm command value V a-fb Calculates the feedback voltage norm command value V a-fb is the command value for the voltage norm Va by feedback control. Feedback voltage norm command value V a-fb is input to the adder 71.

[0071]

number

[0072] In addition, "K" in formula (8) φp " is the proportional gain, and "K φi " is the integral gain. In this embodiment, the proportional gain K φp and integral gain K φi is a variable value, and is set by the delay time setting unit 29 to the power supply voltage V dc It is set or changed depending on the power supply voltage V dc and control mode, etc., and proportional gain K φpand integral gain K φi The relationship regarding the settings etc. will be described in detail later.

[0073] The adder 71 calculates the feedforward voltage norm command value V a-ff and the feedback voltage norm command value V input from the first feedback system 43 as described above. a-fb As a result, the adder 71 calculates the voltage norm command value V a * Calculates the voltage norm command value V a * is input to the voltage norm command value limiting unit 72.

[0074] The voltage norm command value limiting unit 72 limits the power supply voltage V dc Based on this, the voltage norm command value V a * The lower limit (zero) is greater than or equal to a predetermined upper limit V a-max The voltage norm command value V is limited to the following value. a * Lower and upper limits V a-max is determined in advance. Specifically, the voltage norm command value V a * The upper limit of the power supply voltage V dc The "M" in the formula (9) is determined in advance according to max * " is the reference modulation rate M * The maximum value that can be set as the reference modulation factor M * is the maximum allowable value.

[0075]

number

[0076] The voltage norm command value V a * is the upper limit V a-max While this is the case, the voltage norm V ais fixed. Therefore, only the torque feedback for the voltage phase α, which will be described later, functions. Also, the voltage norm command value V a * is the upper limit V a-max While this is the case, the voltage norm command value limiting unit 72 controls the PI control unit 56 to limit the voltage norm command value V a * While receiving this notification signal, the PI control unit 56 stops the integral calculation for anti-windup purposes.

[0077] The voltage norm command value V output by the adder 71 a * is the upper limit V a-max When the voltage norm command value V is less than or equal to the voltage norm command value V a * is the final voltage norm command value V a * On the other hand, the voltage norm command value V a * is the upper limit V a-max When the voltage norm command value V a * The upper limit V a-max is the final voltage norm command value V a * are input to the vector conversion unit 75 as

[0078] The second feedback system 44 is a system that feeds back the current value of the electric motor 11 or a parameter calculated from the current value of the electric motor 11 to the voltage phase α. In this embodiment, the second feedback system 44 feeds back the dq-axis current i d ,i q Calculate the parameters related to the torque T from the voltage phase command value α * Feedback to.

[0079] Specifically, the second feedback system 44 includes a reference torque calculation unit 61, a torque estimation unit 62, a deviation calculation unit 63, and a PI control unit 64.

[0080] The reference torque calculation unit 61 calculates the torque command value T * Based on the reference torque T ref Calculate the reference torque T ref represents the target response of the torque T. The reference torque calculation unit 61 is configured by a filter such as a low-pass filter (LPF), a band-pass filter, a moving average filter, a Gaussian filter, or a median filter. In this embodiment, the reference torque calculation unit 61 is a low-pass filter. The reference torque T ref is input to the deviation calculation unit 63.

[0081] The torque estimation unit 62 estimates the dq-axis current i d ,i q Based on this, the torque estimate T est The torque estimation unit 62 calculates, for example, the dq-axis current i d ,i q and the torque estimate T est The torque estimation unit 62 stores in advance a torque table (look-up table) in which the torques are associated with each other based on experiments, simulations, etc. Therefore, the torque estimation unit 62 can obtain the torque estimation value T est The torque estimate T est is input to the deviation calculation unit 63.

[0082] The deviation calculation unit 63 calculates the reference torque T ref and the torque estimate T est The torque deviation T err In this embodiment, the deviation calculation unit 63 calculates the reference torque T ref from the torque estimate T est By subtracting the torque deviation T err Calculate the torque deviation T err is input to the PI control unit 64.

[0083] The PI control unit 64 calculates the voltage phase α as a voltage phase command value α * Specifically, the PI control unit 64 calculates the torque deviation T err (=T ref -T est ) based on the feedback voltage phase command value α fb Calculate the feedback voltage phase command value α fb is a command value by feedback control for the voltage phase α. Feedback voltage phase command value α fb is input to the adder 73.

[0084]

number

[0085] In addition, "K" in formula (10) αp " is the proportional gain, and "K αi " is the integral gain. In this embodiment, the proportional gain K αp and integral gain K αi is a predetermined fixed value.

[0086] The adder 73 calculates the feedforward voltage phase command value α ff and the feedback voltage phase command value α input from the second feedback system 44 as described above. fb As a result, the adder 73 calculates the voltage phase command value α * Calculate the voltage phase command value α * is input to the voltage phase command value limiting unit 74.

[0087] The voltage phase command value limiting unit 74 limits the voltage phase command value α * a predetermined lower limit value α min to a predetermined upper limit value α max The voltage phase command value α is limited to the range * The lower limit α min and upper limit value α maxis predetermined by the characteristics of the electric motor 11.

[0088] 5 is a graph showing an example of the relationship between the voltage phase α and the torque T. For example, when the electric motor 11 has the characteristics shown in FIG. 5, the voltage phase command value α * The range in which the correlation between the voltage phase command value α and the torque T is maintained is approximately ±105 degrees. * The lower limit α min is -105 degrees, upper limit α max is set to +105 degrees.

[0089] The voltage phase command value limiting unit 74 limits the voltage phase command value α * is the lower limit α min or upper limit α max While this is the case, the voltage phase command value α * is fixed. Therefore, the voltage norm V a In this state, only the feedback of the magnetic flux norm for the voltage phase command value α * is the lower limit α min or upper limit α max While this is the case, the voltage phase command value limiting unit 74 controls the PI control unit 64 to limit the voltage phase command value α * While receiving this notification signal, the PI control unit 64 stops the integral calculation for anti-windup purposes.

[0090] The voltage phase command value α output by the adder 73 * is the lower limit α min Above, upper limit α max When the voltage phase command value α is within the range below, the voltage phase command value α output by the adder 73 is substantially * is the final voltage phase command value α * On the other hand, due to the limitation in the voltage phase command value limiting unit 74, the voltage phase command value α * is the lower limit α min or upper limit α max When the voltage phase command value limiting unit 74 is limited to minor upper limit α max is the final voltage phase command value α * are input to the vector conversion unit 75 as

[0091] The vector conversion unit 75 (see FIG. 4) converts the voltage norm command value V a * and receives the voltage phase command value α * Then, the vector conversion unit 75 converts the voltage norm command value V a * and voltage phase command value α * Based on this, the dq-axis voltage command value V dv-fin * ,V qv-fin * Calculate the dq-axis voltage command value V dv-fin * ,V qv-fin * is input to the control mode switching unit 28 as described above.

[0092]

number

[0093] [Configuration of control mode switching section] 6 is a block diagram showing the configuration of the control mode switching unit 28. As shown in FIG. 6, the control mode switching unit 28 includes a switch 81 and a control mode determination unit 82.

[0094] The switch 81 receives the mode selection signal S mode Based on the mode selection signal S, the control mode is switched between a first control mode in which the motor 11 is controlled by current vector control and a second control mode in which the motor 11 is controlled by voltage phase control. mode is input from the control mode determination unit 82 to the switch 81. The mode selection signal S mode represents the selection of the first control mode, the switch 81 is di-fin *,V qi-fin * The final dq-axis voltage command value V d-fin * ,V q-fin * On the other hand, the mode selection signal S mode represents the selection of the second control mode, the switch 81 is dv-fin * ,V qv-fin * The final dq-axis voltage command value V d-fin * ,V q-fin * Output as

[0095] The control mode determination unit 82 determines the dq-axis voltage command value V d-fin * ,V q-fin * , power supply voltage V dc , and the control mode to be selected based on all or part of the parameters related to the setting of the delay time by the delay time setting unit 29. In this embodiment, the parameters related to the setting of the delay time by the delay time setting unit 29 include the time constant τ va , switching prohibition period t mask , and the control gain (proportional gain K φp and integral gain K φi In this embodiment, the control mode determination unit 82 determines the dq-axis voltage command value V d-fin * ,V q-fin * , power supply voltage V dc , time constant τ va , and switching prohibition period t mask The control mode determination unit 82 selects the control mode based on the mode selection signal S mode is output to the delay time setting unit 29 and the switch 81.

[0096] 7 is a block diagram showing a specific configuration of the control mode determination unit 82. As shown in FIG.

[0097] The low-pass filter 91 calculates the final dq-axis voltage command value V d-fin * ,V q-fin * By performing averaging processing on the averaged dq-axis voltage command value V d-flt * ,V q-flt * The low-pass filter 91 calculates the dq-axis voltage command value V d-fin * ,V q-fin * In this embodiment, the low-pass filter 91 is one of the elements that sets a variable delay time, particularly for switching the control mode.

[0098] The low-pass filter 91 is, for example, a d-axis voltage command value V d-fin * and a d-axis low-pass filter 91a that averages the q-axis voltage command value V q-fin * However, the d-axis low-pass filter 91a and the q-axis low-pass filter 91b have the same time constant τ va Therefore, unless a distinction is necessary, these are collectively referred to as the low-pass filter 91. The time constant τ of the low-pass filter 91 is va is not a fixed value, but a parameter that is adjusted by the delay time setting unit 29 to set or change the delay time.

[0099] The low-pass filter 91 is an example of a filter that performs averaging processing, and a band-pass filter, a moving average filter, a Gaussian filter, a median filter, or the like can be used instead of the low-pass filter 91. In this case, the delay time setting unit 29 sets the time constant τ va Similarly to setting or changing the parameter for changing the degree of averaging depending on the specific type of filter, etc.

[0100] The voltage norm calculation unit 92 calculates the averaged dq-axis voltage command value V d-flt * ,V q-flt * Based on this, the voltage norm V is calculated using the following equation (12): a The voltage norm calculation unit 92 calculates the calculated voltage norm V a is input to the control mode selection unit 93.

[0101]

number

[0102] The control mode selection unit 93 selects the voltage norm V a , switching prohibition period t mask , and power supply voltage V dc and selects a control mode based on the selected mode selection signal S mode The specific method by which the control mode selection unit 93 selects the control mode is as follows.

[0103] As described above, the control mode determination unit 82 selects the control mode based on the dq-axis voltage command value V d-fin * ,V q-fin * is used, but the control mode determination unit 82 uses the dq-axis voltage command value V d-fin * ,V q-fin *Any state quantity representing the operating state of the motor 11 can be used, including the current (dq-axis current i d ,i q etc.), voltage (dq-axis voltage command value V d-fin * ,V q-fin * The state quantity used by the control mode determination unit 82 to select the control mode is preferably the current, voltage, torque T, or rotation speed N of the electric motor 11.

[0104] [Control mode selection] The control mode selection unit 93 determines the elapsed time t since the last change of the control mode. e The control mode selection unit 93 monitors this by counting or acquiring the elapsed time t e The delay time setting unit 29 sets the switching inhibition period t mask Compare with.

[0105] As shown in Table 1 below, the elapsed time t e is the switching prohibition period t mask When the voltage norm V a It is decided to maintain the current control mode selected last time, regardless of other parameters such as the elapsed time t e is the switching prohibition period t mask If it is less than this, the control mode selection unit 93 reselects the previously selected control mode.

[0106] [Table 1]

[0107] On the other hand, as shown in Table 1 above, the elapsed time t e is the switching prohibition period t mask If the power supply voltage V dcDepending on the result, it is determined whether to switch the control mode or maintain the current control mode.

[0108] Specifically, the control mode selection unit 93 selects a power supply voltage V dc The voltage norm V calculated by the voltage norm calculation unit 92 is calculated using a The first voltage norm threshold Th va1 and the second voltage norm threshold Th va2 The first voltage norm threshold Th va1 is a threshold value for determining whether to switch to the second control mode (voltage phase control). va1 For example, as shown in Table 1 above, va1 =1.05×V dc The second voltage norm threshold Th va2 is a threshold value for determining whether to switch to the first control mode (voltage vector control). va2 For example, as shown in Table 1 above, va2 =1.00×V dc It is calculated by / √2.

[0109] First voltage norm threshold Th va1 is the voltage norm V in the control scene where the effective modulation factor M in PWM control is "1.05". a The control scene where the modulation factor M is "1.05" is clearly a control scene where control of the overmodulation region is required. Therefore, the first voltage norm threshold Th va1 is the criterion for determining whether it is necessary to switch to voltage phase control. va1 The modulation factor M is set to "1.05" instead of "1.00" in order to provide hysteresis to the control mode switching and suppress chattering. dc Since varies depending on the SOC of the power supply 10, the first voltage norm threshold Th va1 is the power supply voltage V dc Specifically, it changes depending on the power supply voltage V dc If becomes smaller, the first voltage norm threshold Thva1 The power supply voltage V dc If becomes larger, the first voltage norm threshold Th va1 also becomes larger.

[0110] Second voltage norm threshold Th va2 is the voltage norm V in the control scene where the effective modulation rate M in PWM control is "1.00". a The control scene where the modulation factor M is "1.00" is a control scene where control in the normal modulation region is possible. Therefore, the second voltage norm threshold Th va2 is the criterion for determining whether to switch to current vector control. dc Since the second voltage norm threshold Th va2 is the power supply voltage V dc Specifically, it changes depending on the power supply voltage V dc If becomes smaller, the second voltage norm threshold Th va2 The power supply voltage V dc If becomes larger, the second voltage norm threshold Th va2 also becomes larger.

[0111] The control mode selection unit 93 selects the voltage norm V calculated by the voltage norm calculation unit 92. a and the power supply voltage V dc The first voltage norm threshold Th calculated as above according to va1 and the second voltage norm threshold Th va2 The control mode is selected by comparing the voltage norm V a is the first voltage norm threshold Th va1 When it is determined that the voltage norm V is greater than V, the control mode selection unit 93 selects the second control mode (voltage phase control). a is the second voltage norm threshold Th va2 When it is determined that the voltage norm Va is smaller than the first voltage norm threshold Th, the control mode selection unit 93 selects the first control mode (current vector control). va1 Second voltage norm threshold Th va2 If so, maintain the current control mode by reselecting it.

[0112] [Delay time setting] In response to the switching of the control mode, the delay time setting unit 29 adjusts the power supply voltage V dc Depending on va , switching prohibition period t mask , and proportional gain K φp and integral gain K φi The delay time is set or changed by setting or changing

[0113] The delay time setting unit 29 sets the power supply voltage V dc Based on experiments or simulations, a first power supply voltage threshold Th vdc1 and the second power supply voltage threshold Th vdc2 In the example of Table 2, the first power supply voltage threshold Th vdc1 is, for example, 250 V, and the second power supply voltage threshold Th vdc2 is, for example, 350 V. The delay time setting unit 29 then sets the first power supply voltage threshold Th vdc1 and the second power supply voltage threshold Th vdc2 , the power supply voltage V dc and based on the comparison result, the time constant τ va Various parameters relating to delay times such as the above are set or changed.

[0114] [Table 2]

[0115] Specifically, as shown in Table 2, when the selected or maintained control mode is the first control mode (current vector control), the delay time setting unit 29 sets the power supply voltage V dc Regardless of the specific value of , the time constant τ va and switching prohibition period t mask is a predetermined value (fixed value). In the example of Table 2, when the control mode is the first control mode (current vector control), the time constant τ va is set to 5ms, and the switching inhibition period tmask is set to 10ms.

[0116] When the control mode is the first control mode (current vector control), the proportional gain K φp and integral gain K φi is the power supply voltage V dc For example, the proportional gain K when the control mode is the first control mode (current vector control) is set to a predetermined value that does not depend on the proportional gain K. φp and integral gain K φi The description of is omitted.

[0117] When the selected or maintained control mode is the second control mode (voltage phase control), the delay time setting unit 29 adjusts the power supply voltage V dc and the first power supply voltage threshold Th vdc1 and the second power supply voltage threshold Th vdc2 Compare with.

[0118] And the power supply voltage V dc is the first power supply voltage threshold Th vdc1 Second power supply voltage threshold Th vdc2 If the delay time is less than or equal to the time constant τ va , switching prohibition period t mask , and the proportional gain K of the PI control unit 56 φp and integral gain K φi is set or changed to a predetermined reference value determined in advance based on an experiment, a simulation, or the like. va The reference value of is, for example, 5 ms, and the switching inhibition period t mask The reference value of is, for example, 10 ms. These are equal to the values ​​set for switching from the first control mode (current vector control) to the second control mode (voltage phase control). In addition, the proportional gain K φp and integral gain K φi The reference values ​​for are, for example, "837.8" and "41.9", respectively.

[0119] In contrast, the power supply voltage Vdc is the first power supply voltage threshold Th vdc1 When the delay time is smaller than the time constant τ va In the example in Table 2, the power supply voltage V dc is the first power supply voltage threshold Th vdc1 When the voltage is less than 250V, the time constant τ va is set to 10 ms, which is larger than the reference value (5 ms).

[0120] Power supply voltage V dc is the first power supply voltage threshold Th vdc1 When the delay time setting unit 29 determines that the switching inhibition period t mask In the example in Table 2, the power supply voltage V dc is the first power supply voltage threshold Th vdc1 When the voltage is less than 250V, the switching prohibition period t mask is set to 20 ms, which is larger than the reference value (10 ms).

[0121] Power supply voltage V dc is the first power supply voltage threshold Th vdc1 When the delay time is smaller than the proportional gain K φp and integral gain K φi In the example in Table 2, the power supply voltage V dc is the first power supply voltage threshold Th vdc1 When the voltage is smaller than 250V, the proportional gain K φp and integral gain K φi are set to "418.9" and "20.9", which are smaller than the reference values ​​("837.8" and "41.9").

[0122] On the other hand, the power supply voltage V dc is the second power supply voltage threshold Th vdc2 When the delay time is larger than the time constant τ va In the example in Table 2, the power supply voltage V dc is the second power supply voltage threshold Thvdc2 When the voltage is less than 350V, the time constant τ va is set to 2 ms, which is smaller than the reference value (5 ms).

[0123] Power supply voltage V dc is the second power supply voltage threshold Th vdc2 When the delay time setting unit 29 determines that the switching inhibition period t mask In the example in Table 2, the power supply voltage V dc is the second power supply voltage threshold Th vdc2 When the voltage is less than 350V, the switching prohibition period t mask is set to 5 ms, which is smaller than the reference value (10 ms).

[0124] Power supply voltage V dc is the second power supply voltage threshold Th vdc2 When the delay time is larger than the proportional gain K φp and integral gain K φi In the example in Table 2, the power supply voltage V dc is the second power supply voltage threshold Th vdc2 When the voltage is smaller than 350V, the proportional gain K φp and integral gain K φi are set to "2094.4" and "104.7", which are larger than the reference values ​​("837.8" and "41.9").

[0125] As described above, the delay time setting unit 29 sets the power supply voltage V dc Depending on va , switching prohibition period t mask , and the proportional gain K of the PI control unit 56 φp and integral gain K φi By setting or changing the delay time, a variable delay time can be set for switching of the control mode. In particular, the delay time for switching from the second control mode (voltage phase control) to the first control mode (current vector control) can be set by changing the delay time of the power supply voltage V dc Change it depending on the

[0126] Specifically, the delay time setting unit 29 sets the time constant τ va and switching prohibition period t mask By setting or changing the supply voltage V dc is the first power supply voltage threshold Th vdc1 When the supply voltage V dc is the first power supply voltage threshold Th vdc1 The delay time is extended compared to when the power supply voltage V dc is the second power supply voltage threshold Th vdc2 When it is greater than the supply voltage V dc is the second power supply voltage threshold Th vdc2 The delay time is reduced compared to the case where the time constant τ va and switching prohibition period t mask The relationship between the delay time and the time will be described in detail later.

[0127] As mentioned above, the power supply voltage V dc the first power supply voltage threshold Th vdc1 and the second power supply voltage threshold Th vdc2 Set the power supply voltage V dc is divided into three sections to extend or shorten the delay time. va In other words, the delay time setting unit 29 basically sets the parameters such as the power supply voltage V dc In order to shorten the delay time as the power supply voltage V dc The larger the time constant τ va and switching prohibition period t mask In principle, the delay time setting unit 29 sets the power supply voltage V dc In order to shorten the delay time as the power supply voltage V dc The larger the proportional gain K of the PI control section 56, φp and integral gain K φi Similarly, the delay time setting unit 29 sets the power supply voltage V dc In order to extend the delay time as the power supply voltage V dc The smaller the time constant τ va and switching prohibition period t maskIn principle, the delay time setting unit 29 sets the power supply voltage V dc The smaller the proportional gain K of the PI control section 56, φp and integral gain K φi Set to a small value.

[0128] [Time constant τ va and switching prohibition period t mask and delay time] Power supply voltage V dc The time constant τ according to va and switching prohibition period t mask The specific relationship between the setting or change of and the delay time for switching the control mode is as follows:

[0129] Switching prohibition period t mask is a parameter that directly limits the switching of the control mode in the electric motor control device 100. Therefore, the switching inhibition period t mask The larger the value, the slower the switching of the control mode in response to a sudden change in the load of the motor 11 becomes, and the longer the switching prohibition period t mask The smaller the value, the quicker the control mode changes in response to a sudden change in load.

[0130] Time constant τ va As mentioned above, the dq-axis voltage command value V d-fin * ,V q-fin * is a parameter that determines the degree of averaging, and the time constant τ va The larger the value of , the greater the dq-axis voltage command value V d-fin * ,V q-fin * is averaged. Therefore, the time constant τ va The larger the time constant τ va The smaller the time constant τ, the quicker the control mode changes in response to a sudden change in load. va Setting or changing the delay time for switching the control mode is synonymous with setting or changing the delay time for switching the control mode.

[0131] [Relationship between delay time setting and durability of semiconductor switching elements] The above-mentioned power supply voltage V dc The delay time is set or changed according to the physical characteristics of the semiconductor switching element 23 (particularly the upper limit voltage V UL ) is as follows:

[0132] First, Figure 8 shows the power supply voltage V dc 8 is an explanatory diagram showing the relationship between the rotation speed N and the torque T, and the control mode switching line. As shown in FIG. 8, the operating state (operating point) of the electric motor 11 is determined by the relationship between the rotation speed N and the torque T, and the control mode switching line. LIM As mentioned above, the control mode switching decision is made based on the power supply voltage V dc , so in FIG. 8, the power supply voltage V dc The control switching line 95 (dotted line) when the power supply voltage V is low voltage V1. dc 10 shows a control switching line 96 (broken line) when the voltage V is a high voltage V2 that is greater than the low voltage V1.

[0133] As indicated by arrows A1 and B1, the control mode selector 93 selects the second control mode (voltage phase control) on the high rotation speed side of the control switching lines 95 and 96. On the other hand, as indicated by arrows A2 and B2, the control mode selector 93 selects the first control mode (voltage vector control) on the low rotation speed side of the control switching lines 95 and 96. Therefore, the power supply voltage V dc When V is low, voltage phase control is applied up to the low rotation speed range, and the power supply voltage V dc When the voltage phase control is high, the voltage phase control is generally applied in the high rotation speed region. The reason why this control mode is selected is that the voltage phase control can obtain good control performance in the so-called flux weakening region.

[0134] Next, Fig. 9 is a graph showing the input / output static characteristics of the motor 11 in voltage phase control. aThis can be considered as a feedback system with the voltage phase α as input and the magnetic flux norm φ and torque T as output (Fig. 4). For this reason, here, under the condition of multiple rotation speeds N, Fig. 9(A) shows the static characteristics of torque T with respect to voltage phase α, and Fig. 9(B) shows the static characteristics of voltage norm V a FIG. 9(B) shows the static characteristics of the magnetic flux norm φ with respect to the magnetic field.

[0135] As shown in FIG. 9(A), in the control configuration of the voltage phase control, the static characteristics of the torque T with respect to the voltage phase α are shown by the arrow N L As shown in the arrow N, the smaller the rotation speed N, the greater the slope. H 9(A) represents the gain of the second feedback system 44 (gain of the open loop transmission system) which receives the voltage phase α and outputs the torque T.

[0136] Similarly, as shown in FIG. 9(B), in the control configuration of the voltage phase control, the static characteristics of the magnetic flux norm φ with respect to the voltage norm Va are shown by the arrow N L As shown by the arrow NH, the smaller the rotation speed N, the steeper the slope. As shown by the arrow NH, the larger the rotation speed N, the steeper the slope. The slope of the graph shown in FIG. 9(B) is the voltage norm V a represents the gain of the first feedback system 43 (gain of the open loop transfer system) which has the magnetic flux norm φ as its output and the magnetic flux norm φ as its input.

[0137] Therefore, taking all of these factors into consideration, voltage phase control is a control system with nonlinear characteristics in which the gain increases as the rotation speed N of the electric motor 11 decreases. For this reason, in voltage phase control, the harmonics superimposed on the current and voltage of the electric motor 11 tend to increase as the rotation speed N of the electric motor 11 decreases.

[0138] 10A and 10B are graphs showing the characteristics of the semiconductor switching element 23. dc When the voltage V is low, the current I sw and voltage V sw and surge width W Mand surge margin V M 10B is a schematic graph showing the relationship between the power supply voltage V dc When the voltage V is high, the current I sw and voltage V sw and surge width W M and surge margin V M 10 is a schematic graph showing the relationship between

[0139] As shown by the thick solid lines in FIGS. 10A and 10B, the surge voltage superimposed during the operation of the semiconductor switching element 23 is dc It is roughly the same regardless of the power supply voltage V dc Surge width W based on M are graphs of the same shape.

[0140] However, the surge voltage is higher than the power supply voltage V dc and the upper limit voltage V of the semiconductor switching element 23. UL is a physical characteristic and is therefore constant. dc is a low voltage V1, and when the power supply voltage V dc is a high voltage V2, the margin for surge voltage, i.e., surge margin V M When comparing the power supply voltage V dc If V2 is high, the surge margin V M becomes smaller. That is, the power supply voltage V dc Surge margin V when V1 is low voltage M "V M1 " and the power supply voltage V dc Surge margin V when V2 is high voltage M "V M2 " If so, V M1 >V M2 is.

[0141] As a result, the power supply voltage V dc is a low voltage V1, and when the power supply voltage V dc When the voltage V1 is high, the upper limit current I UL When comparing the power supply voltage Vdc The higher the voltage V2, the higher the upper limit current I UL becomes smaller. That is, the power supply voltage V dc Upper limit current I when V1 is low UL "I UL1 " and the power supply voltage V dc is the upper limit current I when the high voltage V2 UL "I UL2 "If so, I UL1 >I UL2 is.

[0142] Therefore, the supply voltage V dc When the upper limit current I is low, even if the surge voltage is superimposed, the semiconductor switching element 23 has a margin in withstand voltage performance. UL On the other hand, the power supply voltage V dc When the voltage is high, the upper limit current I UL needs to be limited low.

[0143] As described above, by summarizing the characteristics shown in Figures 8 to 10, the power supply voltage V dc When the voltage phase control is low, a delay in switching from the voltage phase control to the voltage vector control is acceptable from the viewpoint of durability of the semiconductor switching element 23.

[0144] For example, if a sudden deceleration occurs due to a sudden load change during voltage phase control, and the decision to switch the control mode is delayed, causing voltage phase control to continue in an area where current vector control should be performed, a large current due to a surge may flow through the semiconductor switching element 23.

[0145] However, the power supply voltage V dc When the power supply voltage V is low, the semiconductor switching element 23 can tolerate this large current. dc When the rotation speed is low, the control switching line is shifted to the low rotation speed side (i.e., control switching line 95), and by utilizing the fact that the voltage phase control has a high gain characteristic, it is possible to deliberately delay the decision to switch the control mode.

[0146] Therefore, in this embodiment, the delay time setting unit 29 is dc When is low, the time constant τ va and switching prohibition period t mask By intentionally setting a large value, the delay time for switching the control mode is intentionally extended. Such an extended delay time setting has the advantage of suppressing chattering during switching of the control mode in normal control situations where no sudden load changes occur.

[0147] On the other hand, considering the characteristics shown in Figures 8 to 10, the power supply voltage V dc When the voltage phase control is high, a delay in switching from voltage phase control to voltage vector control is not acceptable from the viewpoint of durability of the semiconductor switching element 23.

[0148] For example, as in the above case, a control scenario is assumed in which a sudden load change occurs during voltage phase control and a delay in determining whether to switch the control mode causes voltage phase control to continue in a region where current vector control should be performed. In this case, a large current due to a surge flows through the semiconductor switching element 23, but the power supply voltage V dc When the power supply voltage V is high, such a large current is not permissible from the viewpoint of durability of the semiconductor switching element 23. In other words, a sudden change in load during voltage phase control is not a control item and is therefore unavoidable. Therefore, in the control of the motor control device 100, dc When the control mode switching time is high, a delay in the control mode switching decision cannot be tolerated.

[0149] Therefore, in this embodiment, the delay time setting unit 29 is dc When is high, the time constant τ va and switching prohibition period t mask By setting the value to a small value, the delay time for switching the control mode is shortened, so that when a sudden change in the load occurs during voltage phase control, the control is quickly switched to current vector control.

[0150] Also, the power supply voltage V dcWhen the power supply voltage V is high, the control switching line is shifted to the high rotation speed side (i.e., the control switching line 96), and the voltage phase control has a low gain characteristic. dc When the power supply voltage V is high, chattering during switching of the control mode is unlikely to occur. dc When the load is high, such chattering during switching of the control mode is unlikely to occur, and by utilizing this, chattering during switching of the control mode is suppressed in normal control situations where no sudden change in the load occurs.

[0151] As described above, the delay time setting unit 29 sets the time constant τ va and switching prohibition period t mask The delay time for switching the control mode from the second control mode (voltage phase control) to the first control mode (current vector control) is set by the power supply voltage V dc This allows appropriate switching between current vector control and voltage phase control both during normal operation and when a sudden load change occurs.

[0152] <effect> Hereinafter, the operation of switching the control mode by the motor control device 100 configured as described above will be described.

[0153] 11 is a flowchart showing the operation of the motor control device 100. As shown in FIG. 11, in step S101, the electrical angle θ is acquired, and in step S102, the rotation speed N is calculated based on the electrical angle θ. In addition, in step S103, the current of the motor 11, for example, the U-phase current i u and V-phase current i v is detected, and in step S104, the U-phase current i u and V-phase current i v From dq axis current i d ,i q Then, in step S105, the power supply voltage V dc is acquired, and in step S106, the torque command value T * is obtained.

[0154] Then, in step S107, the delay time setting unit 29 sets the power supply voltage V dc In this embodiment, a variable constant, which is a parameter for setting a delay time for switching the control mode, is selected based on the time constant τ va , switching prohibition period t mask , and the control gain (proportional gain K φp and integral gain K φi ) is the power supply voltage V dc At this time, the delay time setting unit 29 sets or changes the delay time depending on the power supply voltage V dc The smaller the time constant τ, the longer the delay time. va and switching prohibition period t mask The delay time setting unit 29 sets or changes the value of the power supply voltage V dc The smaller the value of , the smaller the control gain in the PI control unit 56 is made.

[0155] Next, in step S108, a calculation for current vector control is executed. Meanwhile, in parallel with this current vector control calculation, in step S109, the control gain (proportional gain K φp and integral gain K φi ) is reflected in the setting. Then, in step S110, calculation for voltage phase control is performed using the control gain set or changed by delay time setting unit 29.

[0156] Then, in step S111, the time constant τ of the low-pass filter 91 is selected from the constants selected by the delay time setting unit 29. va and switching prohibition period t mask Then, in step S112, the dq-axis voltage command value V d-fin * ,V q-fin *and the time constant τ va and switching prohibition period t mask The control mode determination unit 82 determines whether to switch the control mode based on the setting of the control mode. The control mode switching determination is performed based on the elapsed time t e and switching prohibition period t mask Comparison of power supply voltage V dc The voltage norm V is calculated based on a This is done based on the value of

[0157] As described above, the motor control method according to this embodiment determines the target current value (dq-axis current target value i d * ,i q * ) and the current value of the motor 11 (dq axis current i d ,i q ) to control the motor 11. di-fin * ,V qi-fin * ) and a command value (voltage phase command value α * ) to the current value of the electric motor 11 or a parameter calculated based on the current value (torque deviation T err ) is fed back to the voltage command value (the dq-axis voltage command value V dv-fin * ,V qv-fin * ) and a second control mode (voltage phase control) that calculates the power supply voltage V. A delay time is set for switching between the first control mode and the second control mode, and the delay time for switching from the second control mode to the first control mode is set by the power supply voltage V. dc The value is changed depending on the

[0158] In this way, the delay time for switching from the second control mode (voltage phase control) to the first control mode (current vector control) is made variable, and the power supply voltage V dcBy changing the control mode in accordance with the load, it is possible to appropriately switch between current vector control and voltage phase control. Specifically, when there is a sudden load change, the control mode is switched abruptly within the range in which the semiconductor switching element 23 can withstand a surge due to a delay in switching the control mode. At the same time, chattering during control mode switching is suppressed during normal times when there is no sudden load change. In other words, abrupt control mode switching during a sudden load change and chattering suppression during normal times are both achieved.

[0159] In the motor control method according to the above embodiment, the power supply voltage V dc The larger the delay time, the shorter the power supply voltage V dc This makes it easier to achieve both rapid control mode switching when the load suddenly changes and chattering suppression during normal operation.

[0160] The electric motor control method according to the above embodiment is dc , the first threshold (first power supply voltage threshold Th vdc1 ) and a second threshold (second power supply voltage threshold Th vdc2 ) and is set. Then, the power supply voltage V dc When is smaller than the first threshold, the power supply voltage V dc The delay time is extended compared to when the power supply voltage V is equal to or greater than the first threshold. dc When is greater than the second threshold, the power supply voltage V dc is equal to or less than the second threshold value, the delay time is reduced.

[0161] In the motor control method according to the above embodiment, the power supply voltage V dc is the first threshold (first power supply voltage threshold Th vdc1 ) or more than the second threshold (second power supply voltage threshold Th vdc2 ), the delay time for switching from the second control mode (voltage phase control) to the first control mode (current vector control) is set equal to the delay time set for switching from the first control mode (current vector control) to the second control mode (voltage phase control). dcWhen the delay time for switching from the second control mode to the first control mode is set to a value that is neither too high nor too low and is a moderate value, there is relatively little need to take into consideration the durability of the semiconductor switching element 23 against surges and chattering during switching of the control mode. Therefore, by setting the delay time for switching from the second control mode to the first control mode to be approximately the same as the delay time for switching from the first control mode to the second control mode, switching between the current vector control and the voltage phase control can be performed particularly appropriately.

[0162] In the motor control method according to the above embodiment, the state quantity (dq-axis voltage command value V d-fin * ,V q-fin * ), the switching between the first control mode and the second control mode is determined, and the delay time is set by averaging the state quantity (low-pass filter 91). Then, the parameter of the averaging process (time constant τ va ) to the power supply voltage V dc The delay time is changed by changing the delay time in accordance with the state variables used to determine whether to switch the control mode. That is, the delay time is set or changed by averaging the state variables used to determine whether to switch the control mode and adjusting the degree of averaging. This method directly utilizes the correlation between the likelihood of control mode switching chattering occurring and the current increase during a sudden load change, and therefore can particularly appropriately suppress switching chattering and prevent the semiconductor switching element 23 from exceeding its durability.

[0163] In the electric motor control method according to the above embodiment, the state quantity is the current, voltage, torque T, or rotation speed N of the electric motor 11. The first control mode (voltage vector control) is particularly suitable for a control region where it is desired to obtain maximum torque at minimum current, i.e., when low rotation and low torque are required. On the other hand, the second control mode (voltage phase control) is particularly suitable for a flux-weakening region where voltage saturates, i.e., when high rotation and high torque are required. Therefore, if the state quantity for determining switching of the control mode is the current, voltage, torque T, or rotation speed N of the electric motor 11, as described above, these control regions can be directly and appropriately determined. This particularly appropriately suppresses switching chattering and prevents the semiconductor switching elements 23 from exceeding their durability.

[0164] In the electric motor control method according to the above embodiment, a prohibition period (switching prohibition period t mask ) is set. In this way, the switching inhibition period t mask The method of setting the delay time is to directly set or change the delay time. At the same time, this method utilizes the fact that the switching delay time is correlated with chattering and current rise during a sudden load change. Therefore, as described above, the switching inhibition period t mask When the above formula is set, chattering during switching is particularly appropriately suppressed, and the semiconductor switching element 23 is prevented from exceeding its durability.

[0165] In the electric motor control method according to the above embodiment, in the second control mode, the current value of the electric motor 11 (dq axis current i d ,i q ), a parameter related to the magnetic flux of the electric motor 11 (magnetic flux deviation φ err ) and calculates the voltage norm command value V based on the parameters related to this magnetic flux. a * That is, the current value of the motor 11 (dq axis current i d ,i q ) not only the voltage phase α but also the voltage norm V aIn principle, voltage phase control is a control that feeds back the current value to the voltage phase α. However, as mentioned above, the voltage norm V a When the current value is also fed back, a current increase due to an excessive voltage is particularly effectively suppressed during a delay in switching the control mode. That is, even in a control scenario in which a high voltage due to voltage phase control is maintained due to a switching delay when a transition from the second control mode (voltage phase control) to the first control mode (current vector control) is required due to a sudden load change, a current increase is suppressed to within a range that the semiconductor switching element 23 can withstand.

[0166] In the motor control method according to the above embodiment, the power supply voltage V dc In accordance with this, the control gain (proportional gain K φp and integral gain K φi ) is changed. This method dc This method utilizes the correlation between the gain of the loop transfer system of the voltage phase control and the power supply voltage V dc The gain of the loop transfer system increases when is small, but the control gain in the second control mode (voltage phase control) is dc Therefore, according to the above method, it is possible to increase the delay time within a realistic range that does not exceed an allowable value, and also to suppress chattering during switching of the control mode.

[0167] In particular, in the motor control method according to the above embodiment, the power supply voltage V dc The larger the value of V, the higher the control gain in the second control mode (voltage phase control) becomes. dc As the value of θ decreases, the control gain is reduced. This makes it possible to increase the delay time within a practical range that does not exceed an allowable value, and also to suppress chattering during switching of the control mode.

[0168] The above describes embodiments of the present invention, but the configurations described in the above embodiments and each modified example only show some of the application examples of the present invention and are not intended to limit the technical scope of the present invention. [Explanation of symbols]

[0169] 10: Power supply, 11: Motor, 12: Control calculation unit, 13: Coordinate conversion unit, 14: PWM conversion unit, 15: Inverter, 16: Coordinate conversion unit, 17: Rotation speed calculation unit, 21: Voltage detector, 22: Electrical angle detector, 23: Semiconductor switching element, 24: Current detector, 26: Current vector control unit, 27: Voltage phase control unit, 28: Control mode switching unit, 29: Delay time setting unit, 31: Non-interference voltage calculation unit, 32: Averaging processing unit, 33: Current target value calculation unit, 34: Deviation calculation unit, 35: PI control unit, 36: Addition unit, 41: Voltage norm calculation unit, 42: Voltage phase calculation unit, 43: First feedback system, 44: Second feedback system ,51: Current target value calculation unit, 52: Magnetic flux calculation unit, 53: Reference magnetic flux norm calculation unit, 54: Magnetic flux estimation unit, 55: Deviation calculation unit, 56: PI control unit, 61: Reference torque calculation unit, 62: Torque estimation unit, 63: Deviation calculation unit, 64: PI control unit, 71: Addition unit, 72: Voltage norm command value limit unit, 73: Addition unit, 74: Voltage phase command value limit unit, 75: Vector conversion unit, 81: Switch, 82: Control mode determination unit, 91: Low pass filter, 91a: d axis low pass filter, 91b: q axis low pass filter, 92: Voltage norm calculation unit, 93: Control mode selection unit, 95: Control switching line, 96: Control switching line, 100: Motor control device

Claims

1. A motor control method for controlling an electric motor while switching between a first control mode in which a voltage command value for controlling the electric motor is calculated by feeding back a current value of the electric motor to a current target value that is a target value of a current to be supplied to the electric motor, and a second control mode in which a voltage command value is calculated by feeding back the current value or a torque deviation calculated based on the current value to a voltage phase command value that is a command value for a voltage phase to be supplied to the electric motor, setting a delay time for switching between the first control mode and the second control mode; The delay time for switching from the second control mode to the first control mode is shortened as the power supply voltage increases and is lengthened as the power supply voltage decreases. Electric motor control method.

2. 2. The electric motor control method according to claim 1, a first threshold value and a second threshold value greater than the first threshold value are set for the power supply voltage; When the power supply voltage is lower than the first threshold, the delay time is extended compared to when the power supply voltage is equal to or higher than the first threshold; When the power supply voltage is greater than the second threshold, the delay time is reduced compared to when the power supply voltage is equal to or less than the second threshold. Electric motor control method. Electric motor control method.

3. 3. The electric motor control method according to claim 2, when the power supply voltage is equal to or greater than the first threshold and equal to or less than the second threshold, the delay time for switching from the second control mode to the first control mode is set equal to the delay time set for switching from the first control mode to the second control mode. Electric motor control method.

4. The electric motor control method according to any one of claims 1 to 3, determining whether to switch between the first control mode and the second control mode based on a state quantity representing an operating state of the electric motor; setting the delay time by averaging the state quantity; changing the delay time by changing a time constant of the averaging process in accordance with the power supply voltage; Electric motor control method.

5. 5. The electric motor control method according to claim 4, The state quantity is a current, a voltage, a torque, or a rotation speed of the motor. Electric motor control method.

6. The electric motor control method according to any one of claims 1 to 5, As the delay time, a prohibition period during which switching between the first control mode and the second control mode is prohibited is set. Electric motor control method.

7. The electric motor control method according to any one of claims 1 to 6, In the second control mode, a magnetic flux norm deviation of the motor is calculated based on the current value, and a voltage norm command value is calculated based on the magnetic flux norm deviation. Electric motor control method.

8. The electric motor control method according to any one of claims 1 to 7, a control gain in the second control mode is further changed in accordance with the power supply voltage; Electric motor control method.

9. 9. The motor control method according to claim 8, The larger the power supply voltage, the higher the control gain is, and the smaller the power supply voltage, the lower the control gain is. Electric motor control method.

10. an electric motor control device having: a first control unit that controls the electric motor in a first control mode that calculates a voltage command value for controlling the electric motor by feeding back a current value of the electric motor to a current target value that is a target value of a current to be supplied to the electric motor; a second control unit that controls the electric motor in a second control mode that calculates the voltage command value by feeding back the current value or a torque deviation calculated based on the current value to a voltage phase command value that is a command value for a voltage phase to be supplied to the electric motor; and a control mode switching unit that switches between the first control mode and the second control mode, a delay time setting unit that sets a delay time for switching between the first control mode and the second control mode, and that shortens the delay time for switching from the second control mode to the first control mode as a power supply voltage increases and extends the delay time as the power supply voltage decreases; Electric motor control device.

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