Motor control device and motor control method

Abstract

Provided is a motor control device that can reduce torque vibration while preventing overcurrent at the time of a rapid change in rotational speed. This motor control device switches between a plurality of control modes including at least a vector control mode and a voltage phase control mode to control a motor, and is characterized by comprising: a magnetic flux amplitude calculation unit that calculates a magnetic flux amplitude value on the basis of a magnetic flux value of the motor; a magnetic flux command amplitude calculation unit that calculates a magnetic flux command amplitude value on the basis of a magnetic flux command value of the motor; a minimum limiting unit that limits the minimum of the magnetic flux amplitude value on the basis of the magnetic flux command amplitude value; and an integrator initial value computation unit that sets an initial value of an integrator for providing feedback control during the vector control mode and the voltage phase control mode, wherein when the control mode is to be switched, if the magnetic flux amplitude value is less than or equal to the magnetic flux command amplitude value, the minimum limiting unit limits the minimum value of the magnetic flux amplitude value to the magnetic flux command amplitude value.

Description

Motor control device and motor control method

[0001] The present invention relates to a control device configuration and control method for driving a motor, and more particularly to a technology that is effective when applied to a control device for an in-vehicle motor where high stability and reliability are required.

[0002] In conventional gasoline-powered vehicles, the engine and brakes are used for propulsion and braking, respectively, and vehicle motion control is primarily based on the brakes. In contrast, electric vehicles (EVs) can perform both acceleration and deceleration using motors. Motors have a response speed of several milliseconds, which is more than two orders of magnitude faster than engines, and unlike engines, they can accurately grasp the generated torque (rotational force). Therefore, EVs are capable of more advanced motion control than gasoline-powered vehicles.

[0003] Furthermore, with EVs equipped with in-wheel motors, the driving force of all four wheels can be controlled independently, minimizing vertical sway during acceleration and deceleration, as well as lateral sway when cornering, allowing for more stable control of the vehicle's posture.

[0004] As background technology for this field, for example, there is technology such as that described in Patent Document 1. Patent Document 1 discloses a "rotating electric machine control system that can suppress variations in the switching timing from a rectangular wave control mode to an overmodulation control mode."

[0005] Japanese Patent Publication No. 2010-246282

[0006] Main motors for automobiles primarily use interior permanent magnet synchronous motors (IPMSMs), and there is a demand for smaller size and higher output from IPMSMs. To meet these demands, in addition to asynchronous PWM control in the low-speed range, synchronous pulse-reducing control modes have been developed and are being put into practical use. These modes output pulses synchronized to the fundamental frequency, such as one-pulse (square wave) control and three-pulse control, which make effective use of voltage.

[0007] In these control modes, manipulation of voltage amplitude is limited (especially amplitude manipulation is not possible with a single pulse). Therefore, voltage phase control, which controls only the voltage phase, is used instead of two-axis vector control, which assumes manipulation of both voltage phase and amplitude. Consequently, it is necessary to switch controllers when transitioning from asynchronous PWM control to voltage phase control, and vice versa.

[0008] Furthermore, these controllers utilize integrators, such as PI control, to eliminate steady-state deviations from the target control variable. Therefore, when switching controllers, it is necessary to set appropriate initial values ​​for the integrator to prevent step-like changes in the output voltage during switching. If the integrator is not properly initialized, the current and torque will fluctuate and vibrate during control switching, leading to a deterioration in ride comfort and increased noise and vibration in the vehicle system.

[0009] The method for initializing an integrator is to calculate its initial value based on current and magnetic flux and set it in the integrator. Ideally, the current and magnetic flux used in this calculation should contain only the fundamental wave component, but in reality, the waveform will contain harmonics, and these harmonics will cause errors in the initial value of the integrator. In particular, in these low-pulse control modes, a relatively low-order 6th-order ripple (a pulsating component contained in DC current, output torque, and current and magnetic flux on the dq axis; 5th and 7th-order components on a three-phase system) is generated relative to the fundamental wave, and this ripple is superimposed on the actual magnetic flux and current. This ripple causes the actual magnetic flux and current to deviate from their fundamental wave component when switching control modes, resulting in fluctuations and oscillations in current and torque during control switching.

[0010] One method to suppress the generation of sixth-order ripple is to initialize the integrator using flux and current commands instead of actual flux and current. This method utilizes the fact that in a steady state, the fundamental wave components of the actual flux and current coincide with the command values. However, in transient states, such as when the rotational speed changes abruptly, the actual flux and current deviate significantly from the command values. If the integrator is reset using the command values ​​in this case, a large change in output voltage occurs, causing the current to oscillate significantly, and in some cases, overcurrent can cause the inverter control to stop.

[0011] In the above-mentioned Patent Document 1, the fundamental wave component of the actual current is calculated, and the control is switched based on this, so that, as shown in Figure 6, the control can be set to the maximum efficiency characteristic line 62 instead of the switching threshold line 64, which is the switching line of the conventional technology. However, if the fundamental wave component cannot be calculated in transient conditions such as when the rotational speed changes abruptly, an overcurrent may occur.

[0012] Therefore, the object of the present invention is to provide a motor control device and a motor control method using the same that can reduce torque vibration while preventing overcurrent during sudden changes in rotational speed.

[0013] To solve the above problems, the present invention provides a motor control device that controls a motor by switching between a plurality of control modes, including at least a vector control mode and a voltage phase control mode, comprising: a magnetic flux amplitude calculation unit that calculates a magnetic flux amplitude value based on the magnetic flux value of the motor; a magnetic flux command amplitude calculation unit that calculates a magnetic flux command amplitude value based on the magnetic flux command value of the motor; a lower limit unit that sets a lower limit on the magnetic flux amplitude value based on the magnetic flux command amplitude value; and an integrator initial value calculation unit that sets an initial value for an integrator for performing feedback control in the vector control mode and the voltage phase control mode, wherein when switching the control mode, the lower limit unit limits the lower limit of the magnetic flux amplitude value to the magnetic flux command amplitude value if the magnetic flux amplitude value is less than or equal to the magnetic flux command amplitude value.

[0014] Furthermore, the present invention relates to a motor control method for controlling a motor by switching between a plurality of control modes, including at least a vector control mode and a voltage phase control mode, comprising: (a) a step of calculating a magnetic flux amplitude value based on the magnetic flux value of the motor; (b) a step of calculating a magnetic flux command amplitude value based on the magnetic flux command value of the motor; (c) a step of setting a lower limit on the magnetic flux amplitude value calculated in step (a) based on the magnetic flux command amplitude value calculated in step (b); and (d) a step of setting an initial value for an integrator for performing feedback control in the vector control mode and the voltage phase control mode, wherein when switching the control mode, in step (c), if the magnetic flux amplitude value is less than or equal to the magnetic flux command amplitude value, the lower limit of the magnetic flux amplitude value is limited to the magnetic flux command amplitude value.

[0015] According to the present invention, it is possible to realize a motor control device and a motor control method using the same that can reduce torque vibration while preventing overcurrent during sudden changes in rotational speed.

[0016] This can contribute to improving the performance of in-vehicle motor systems.

[0017] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments.

[0018] This figure shows the schematic configuration of a motor system according to Embodiment 1 of the present invention. This is a functional block diagram showing the configuration of the controller 5 in Figure 1. This is a functional block diagram showing the configuration of the current control unit 15 in Figure 2. This is a functional block diagram showing the configuration of the vector control unit 20 in Figure 3. This is an enlarged view of the amplitude calculation units 28, 29 and the lower limit unit 30 in Figure 4. This is a functional block diagram showing the configuration of the lower limit unit 30 in Figure 4. This figure shows an example of the effect according to Embodiment 1. This figure shows an example of the effect according to Embodiment 1. This is a functional block diagram showing the configuration of the vector control unit 20 according to Embodiment 2 of the present invention. This figure shows the operation during a sudden change in rotational speed. This is a flowchart of the motor control method according to Embodiment 1 of the present invention.

[0019] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, identical components are denoted by the same reference numerals, and detailed descriptions of overlapping parts are omitted.

[0020] A motor control device according to Embodiment 1 of the present invention and a motor control method using the same will be described with reference to Figures 1 to 8 and Figures 10 and 11.

[0021] Figure 1 is a diagram showing the schematic configuration of the motor system of this embodiment. Figure 2 is a functional block diagram showing the configuration of the controller 5 in Figure 1. Figure 3 is a functional block diagram showing the configuration of the current control unit 15 in Figure 2. Figure 4 is a functional block diagram showing the configuration of the vector control unit 20 in Figure 3. Figure 5 is an enlarged view of the amplitude calculation units 28, 29 and the lower limit unit 30 in Figure 4. Figure 6 is a functional block diagram showing the configuration of the lower limit unit 30 in Figure 4. Figures 7 and 8 are diagrams showing examples of the effects of this embodiment. Figure 10 is a diagram showing the operation during a sudden change in rotational speed. Figure 11 is a flowchart showing the motor control method of this embodiment.

[0022] As shown in Figure 1, the motor system of this embodiment mainly comprises a motor 2 to be controlled, an inverter 1 for driving and controlling the motor 2, and a battery 3 for supplying DC power to the inverter 1. The motor 2 is an AC motor, such as an embedded magnet synchronous motor (IPMSM). The inverter 1 is a DC / AC type power converter that converts the DC power supplied from the battery 3 into AC power and supplies it to the motor 2.

[0023] The inverter 1 comprises a power conversion unit 4, a controller 5, a gate drive circuit 7, a voltage sensor 8, and a current sensor 10. The motor 2 is equipped with a magnetic pole position sensor 11 for measuring the magnetic pole position of the motor 2.

[0024] The power conversion unit 4 consists of six semiconductor switches Q1 to Q6, six diodes D1 to D6, and a smoothing capacitor 12. Each of the diodes D1 to D6 is connected in antiparallel to each other with respect to the semiconductor switches Q1 to Q6.

[0025] A semiconductor switch Q1 and diode D1 form one upper arm, and a semiconductor switch Q2 and diode D2 form one lower arm, with these upper and lower arms forming one leg. Similarly, a semiconductor switch Q3 and diode D3 form one upper arm, and a semiconductor switch Q4 and diode D4 form one lower arm, with these upper and lower arms forming one leg. Similarly, a semiconductor switch Q5 and diode D5 form one upper arm, and a semiconductor switch Q6 and diode D6 form one lower arm, with these upper and lower arms forming one leg. A three-phase AC output is drawn from the connection point of each upper and lower arm and connected to the motor 2 via a current sensor 10.

[0026] Controller 5 receives the torque command value T from the higher-level control system. ０ ＊ Based on the DC voltage Vdc on the input side of the power conversion unit 4 detected by the voltage sensor 8, the current values ​​iu, iv, and iw of each phase (U phase, V phase, W phase) of the three-phase AC output detected by the current sensor 10, and information regarding the magnetic pole position of the motor 2 (rotor angle θ) detected by the magnetic pole position sensor 11, a gate signal 6 is generated and output to the gate drive circuit 7. The gate drive circuit 7 turns each semiconductor switch Q1 to Q6 ON / OFF based on the input gate signal 6.

[0027] The configuration and operation of the controller 5 will be explained using Figure 2. As shown in Figure 2, the controller 5 comprises a torque control unit 13, a current command value calculation unit 14, a current control unit 15, a dq conversion unit 16, a modulation rate calculation control mode determination unit 17, a voltage control unit 18, and a PWM gate control unit 19.

[0028] Torque command value T from the higher-level control system ０ ＊ This is input to the torque control unit 13. The torque control unit 13 receives the torque command value T ０ ＊ Based on the final torque command T ＊ The current command value is calculated and input to the current command value calculation unit 14. The current command value calculation unit 14 calculates the final torque command T ＊ Based on the dq axis current command value id＊ , iq ＊ is calculated and input to the current control unit 15.

[0029] On the other hand, the current values iu, iv, iw detected by the current sensor 10 and the rotor angle θ detected by the magnetic pole position sensor 11 are input to the dq conversion unit 16. The dq conversion unit 16 calculates dq-axis current command values id, iq based on the current values iu, iv, iw and the rotor angle θ, and inputs them to the current control unit 15.

[0030] The current control unit 15 receives the control mode input from the modulation ratio calculation control mode determination unit 17, the dq-axis current command values id ＊ , iq ＊ from the current command value calculation unit 14, and the dq-axis current command values id, iq from the dq conversion unit 16, and calculates dq-axis voltage command values Vd ＊ , Vq ＊ based on these values, and inputs them to the voltage control unit 18 and the modulation ratio calculation control mode determination unit 17. <​​​​​​​​​​​​​The vector control unit 20 has a vector control configuration based on magnetic flux as disclosed in Japanese Patent No. 7362523. Based on the dq-axis current command values id*, iq*, the dq-axis current values id, iq, the control mode, and the rotor temperature Tr, it calculates the dq-axis voltage command values Vd**, Vq** by vector control that controls the current using the inverse model of the motor 2 based on the magnetic flux, and inputs them to the coordinate conversion unit 22.

[0035] The voltage phase control unit 21 calculates a correction amount θv by voltage phase control based on the dq-axis current command values id*, iq* and the dq-axis current values id, iq and the control mode, and inputs it to the coordinate conversion unit 22.

[0036] The coordinate conversion unit 22 calculates the dq-axis voltage command values Vd*, Vq* using the formula shown in FIG. 3 based on the dq-axis voltage command values Vd**, Vq** input from the vector control unit 20 and the correction amount θv input from the voltage phase control unit 21, and inputs them to the voltage control unit 18 and the modulation ratio calculation control mode determination unit 17 (see FIG. 2).

[0037] In the configuration of FIG. 3, during voltage phase control, the dq-axis voltage command values Vd**, Vq** are fixed at the values at the time of switching, and during vector control operation, the correction amount θv is set to 0.

[0038] The configuration and operation of the vector control unit 20, which is a characteristic part of this embodiment, will be described using FIGS. 4 and 5. As shown in FIG. 4, the vector control unit 20 mainly includes 23, an amplitude calculation unit (magnetic flux amplitude calculation unit) 28, an amplitude calculation unit (magnetic flux command amplitude calculation unit) 29, a lower limit limit unit 30, an integrator 34, and an integrator initial value calculation unit 48. The integrator 34 has an integrator 35 and an integrator 36.

[0039] Based on the input dq-axis current command values \(i_d^*\) and \(i_q^*\), the magnetic flux calculation unit 23 calculates the dq-axis magnetic flux command values \(\varphi_d^*\) and \(\varphi_q^*\) by referring to a pre-registered table. Also, based on the input dq-axis current values \(i_d\) and \(i_q\), the dq-axis magnetic flux values \(\varphi_{dc}\) and \(\varphi_{qc}\) are calculated by referring to a pre-registered table. Further, based on the input rotor temperature \(T_r\), the coefficient \(K_{ec}\) of the magnet flux is calculated by referring to a pre-registered table. In this embodiment, various physical quantities are calculated by referring to tables, but they may also be calculated using approximation formulas or the like.

[0040] The d-axis magnetic flux command value \(\varphi_d^*\) and the d-axis magnetic flux value \(\varphi_{dc}\) calculated by the magnetic flux calculation unit 23 are added and subtracted by the adder-subtractor 24, then multiplied by the cut-off frequency by the gain 26, and input to the integrator 35. Also, the q-axis magnetic flux command value \(\varphi_q^*\) and the q-axis magnetic flux value \(\varphi_{qc}\) are added and subtracted by the adder-subtractor 25, then multiplied by the cut-off frequency by the gain 27, and input to the integrator 36. Further, the d-axis magnetic flux value \(\varphi_{dc}\) and the q-axis magnetic flux value \(\varphi_{qc}\) are input to the integrator initial value calculation unit 48 to calculate the d and q-axis integrator reset signals \(\varphi_d'\) and \(\varphi_q'\).

[0041] When the control mode output from the modulation ratio calculation control mode determination unit 17 is vector control, the integrator 35 integrates the input from the gain 26 and outputs the second d-axis magnetic flux command value \(\varphi_d^{**}\). When the control mode is voltage phase control, the integration operation is stopped. When the control mode switches from voltage phase control to vector control, the integration initial value is set to the d-axis integrator reset signal \(\varphi_d'\). When the control mode output from the modulation ratio calculation control mode determination unit 17 is vector control, the integrator 36 integrates the input from the gain 27 and outputs the second q-axis magnetic flux command value \(\varphi_q^{**}\). When the control mode is voltage phase control, the integration operation is stopped. When the control mode switches from voltage phase control to vector control, the integration initial value is set to the q-axis integrator reset signal \(\varphi_q'\).

[0042] The d-axis magnetic flux command value φd** output from the integrator 35 is input to the adder / subtractor 37, the differentiator 41, and the integrator 43, respectively. The q-axis magnetic flux command value φq** output from the integrator 36 is input to the integrator 44 and the proportionalizer 45, respectively. The adder / subtractor 37 adds or subtracts the input d-axis magnetic flux command value φd** from the magnetic flux coefficient Kec calculated by the magnetic flux calculation unit 23, and inputs the result to the proportionalizer 42.

[0043] The q-axis magnetic flux command value φq** output from the integrator 36 is input to the integrator 44 and the proportionalizer 45, respectively. The d-axis magnetic flux command value φd**, differentiated by the differentiator 41, is added to the result of the proportionalizer 42 in the adder 38, and then added to or subtracted from the result of the integrator 44 in the subtractor 39 to calculate the d-axis voltage command value Vd**. Meanwhile, the result of the integrator 43 and the result of the proportionalizer 45 are added together in the adder 40 to calculate the q-axis voltage command value Vq**.

[0044] Here, the operation of the integrator initial value calculation unit 48 will be explained using Figure 5. The d-axis magnetic flux value φdc and the q-axis magnetic flux value φqc are input to the amplitude calculation unit (magnetic flux amplitude calculation unit) 28, and the magnetic flux amplitude value |φ| is calculated. In addition, the d-axis magnetic flux command value φd* and the q-axis magnetic flux command value φq* are input to the amplitude calculation unit (magnetic flux command amplitude calculation unit) 29, and the magnetic flux command amplitude value |φ*| is calculated.

[0045] The magnetic flux amplitude value |φ| calculated by the amplitude calculation unit (magnetic flux amplitude calculation unit) 28 is input to the divider 31 and also to the lower limit unit 30. The lower limit unit 30 sets a lower limit on the magnetic flux amplitude value |φ| based on the magnetic flux command amplitude value |φ*| calculated by the amplitude calculation unit (magnetic flux command amplitude calculation unit) 29, and calculates the lower limit magnetic flux amplitude value |φ'|. The calculated lower limit magnetic flux amplitude value |φ'| is input to the divider 31. The divider 31 performs a calculation using the input magnetic flux amplitude value |φ| and the lower limit magnetic flux amplitude value |φ'|, and inputs the calculation result to the multiplier 32 and the multiplier 33, respectively.

[0046] The multiplier 32 obtains the d-axis magnetic flux value φd' by multiplying the d-axis magnetic flux value φdc calculated by the magnetic flux calculation unit 23 by the calculation result of the divider 31. The multiplier 33 obtains the q-axis magnetic flux value φq' by multiplying the q-axis magnetic flux value φqc calculated by the magnetic flux calculation unit 23 by the calculation result of the divider 31.

[0047] The configuration and operation of the lower limit unit 30 will be explained using Figure 6. As shown in Figure 6, the lower limit unit 30 includes a comparator 46 and a switch 47. The magnetic flux amplitude value |φ| and the magnetic flux command amplitude value |φ*| input to the lower limit unit 30 are input to the comparator 46 and also to the switch 47. The comparator 46 determines the relative magnitudes of the magnetic flux amplitude value |φ| and the magnetic flux command amplitude value |φ*|, and the result is input to the switch 47.

[0048] Switch 47, when the magnetic flux amplitude value |φ| is less than or equal to the magnetic flux command amplitude value |φ*|, limits the lower limit of the magnetic flux amplitude value |φ| to the magnetic flux command amplitude value |φ*| and outputs the lower limit magnetic flux amplitude value |φ'|, which is the magnetic flux amplitude value after the limit. Therefore, when the magnetic flux amplitude value |φ| is less than or equal to the magnetic flux command amplitude value |φ*|, the lower limit magnetic flux amplitude value |φ'| = magnetic flux command amplitude value |φ*|, and in all other cases, the lower limit magnetic flux amplitude value |φ'| = magnetic flux amplitude value |φ|.

[0049] The effects of this embodiment will be explained using Figures 7, 8, and 10. In Figure 7, the elapsed time from the start of vehicle deceleration is shown on the horizontal axis, and each motor control parameter is shown on the vertical axis, both as relative values. In Figures 8 and 10, the elapsed time from the start of vehicle deceleration is shown on the horizontal axis, and magnetic flux is shown on the vertical axis, both as relative values. As shown in Figure 10, when the rotational speed changes abruptly due to the start of deceleration, the actual value (magnetic flux amplitude value |φ|) exceeds the amplitude of the command value (magnetic flux command amplitude value |φ*|), and the system operates in that state. Therefore, in order to achieve stable operation, it is necessary to reset the system to the actual value (magnetic flux amplitude value |φ|).

[0050] Therefore, as shown in Figure 8, in this embodiment, the amplitude of the actual magnetic flux (magnetic flux amplitude value |φ|) and the amplitude of the magnetic flux command (magnetic flux command amplitude value |φ*|) are calculated, and a limit is set so that the actual magnetic flux amplitude (magnetic flux amplitude value after lower limit |φ'|) ​​exceeds the magnetic flux command amplitude (magnetic flux command amplitude value |φ*|).

[0051] In vector control, the ω1 term of the voltage equation shown in equation (1) below is output, so in the steady state, the integrator outputs are φd and φq for the dq axes, respectively.

[0052] When switching from voltage phase control to vector control, the same φd and φq values ​​as motor 2 are set as the initial integral values. When harmonics are superimposed on φd and φq, if an integral reset is applied with a value below the command value, the output voltage will be lower than that of the motor terminals, causing a torque shock. Therefore, when the value falls below the command value, an integral reset is applied with the command value. During sudden changes in rotational speed, the actual value exceeds the command value, so overcurrent can be prevented by applying a reset with the higher value.

[0053] As a result, as shown in Figure 7, it is possible to reduce torque vibration while preventing overcurrent during sudden changes in rotational speed.

[0054] Figure 11 illustrates a typical flow of the motor control method described above.

[0055] First, in step S1, the magnetic flux amplitude value |φ| is calculated based on the dq axis magnetic flux values ​​φdc and φqc of the motor 2. Next, in step S2, the magnetic flux command amplitude value |φ*| is calculated based on the dq axis magnetic flux command values ​​φd* and φq* of the motor 2. Next, in step S3, a lower limit is set for the magnetic flux amplitude value |φ| based on the magnetic flux command amplitude value |φ*| calculated in step S2. Finally, in step S4, the initial value of the integrator for performing feedback control in vector control mode and voltage phase control mode is set.

[0056] As described above, the motor control device (controller 5) of this embodiment is a motor control device that controls the motor 2 by switching between a plurality of control modes, including at least a vector control mode and a voltage phase control mode. It includes an amplitude calculation unit (magnetic flux amplitude calculation unit) 28 that calculates a magnetic flux amplitude value |φ| based on the dq axis magnetic flux values ​​φdc and φqc of the motor 2, an amplitude calculation unit (magnetic flux command amplitude calculation unit) 29 that calculates a magnetic flux command amplitude value |φ*| based on the dq axis magnetic flux command values ​​φd* and φq* of the motor 2, a lower limit unit 30 that sets a lower limit for the magnetic flux amplitude value |φ| based on the magnetic flux command amplitude value |φ*|, and an integrator initial value calculation unit 48 that sets an initial value for the integrator 34 for performing feedback control in the vector control mode and the voltage phase control mode. When switching control modes, the lower limit unit 30 limits the lower limit of the magnetic flux amplitude value |φ| to the magnetic flux command amplitude value |φ*| if the magnetic flux amplitude value |φ| is less than or equal to the magnetic flux command amplitude value |φ*|.

[0057] According to this embodiment, for example, torque fluctuations can be avoided when switching from voltage phase control to vector control. Furthermore, the control mode can be stably switched in transient states such as sudden changes in rotational speed. If the amplitude of the actual magnetic flux φ used for integral reset |φ| falls below the amplitude of the magnetic flux command φ* |φ*|, a step occurs in the modulation rate, causing a torque shock. Therefore, integral reset is performed at a value with a limit set so that the actual magnetic flux amplitude |φ| exceeds the magnetic flux command amplitude |φ*|. In sudden changes in rotational speed, the actual magnetic flux φ becomes larger than the command value φ*, and the actual magnetic flux φ and the magnetic flux command φ* diverge significantly. In this invention, when the actual magnetic flux φ becomes large, the switch is made using that information directly, thus eliminating the problem.

[0058] Referring to Figure 9, a motor control device according to Embodiment 2 of the present invention and a motor control method using the same will be described. In this embodiment, in addition to the configuration of Embodiment 1 (Figure 4), an example in which a low-pass filter 49 is provided in the vector control unit 20 will be described.

[0059] Figure 9 is a functional block diagram showing the configuration of the vector control unit 20 in this embodiment. As shown in Figure 9, the vector control unit 20 in this embodiment has a low-pass filter 49 between the magnetic flux calculation unit 23 and the amplitude calculation unit (magnetic flux command amplitude calculation unit) 29. The other configurations are the same as in Embodiment 1 (Figure 4).

[0060] The low-pass filter 49 hardly attenuates components at frequencies below a predetermined cutoff frequency, while reducing components at frequencies above the predetermined cutoff frequency. The d-axis magnetic flux command value φd* and the q-axis magnetic flux command value φq* calculated by the magnetic flux calculation unit 23 are reduced by the low-pass filter 49 to obtain the d-axis magnetic flux command value φdf* and the q-axis magnetic flux command value φqf*, which are then input to the amplitude calculation unit (magnetic flux command amplitude calculation unit) 29. The amplitude calculation unit (magnetic flux command amplitude calculation unit) 29 calculates the magnetic flux command amplitude value |φ*| based on the d-axis magnetic flux command value φdf* and the q-axis magnetic flux command value φqf*.

[0061] Furthermore, in order to ensure that the filtered dq-axis magnetic flux command values ​​φdf* and φqf* reproduce the response of the actual magnetic flux φ, the cutoff frequency (filter cutoff angular frequency) is set to the same value as the current control cutoff angular frequency ωc.

[0062] In this embodiment, the vector control unit 20 calculates the magnetic flux command amplitude value |φ*| based on the d-axis magnetic flux command value φdf* and the q-axis magnetic flux command value φqf*, which are obtained by reducing the components with frequencies higher than a predetermined cutoff frequency. As a result, the d and q-axis integrator reset signals φd' and φq' become approximately equal to the fundamental wave components of the actual magnetic fluxes φd and φq, enabling more stable motor control.

[0063] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0064] 1...Inverter, 2...Motor, 3...Battery, 4...Power conversion unit, 5...Controller, 6...Gate signal, 7...Gate drive circuit, 8...Voltage sensor, 9...Duty signal, 10...Current sensor, 11...Magnetic pole position sensor, 12...Smoothing capacitor, 13...Torque control unit, 14...Current command value calculation unit, 15...Current control unit, 16...dq conversion unit, 17...Modulation rate calculation control mode determination unit, 18...Voltage control unit, 19...PWM gate control unit, 20...Vector control unit, 21...Voltage phase control unit, 22...Coordinate 23...Conversion unit, 24, 25, 37, 39...Magnetic flux calculation unit, 26, 27, 34, 35, 36, 43, 44...Integrator, 28...Amplitude calculation unit (magnetic flux amplitude calculation unit), 29...Amplitude calculation unit (magnetic flux command amplitude calculation unit), 30...Lower limit unit, 31...Divider, 32, 33...Multiplier, 38, 40...Adder, 41...Differentiator, 42, 45...Proportional unit, 46...Comparator, 47...Switch, 48...Integrator initial value calculation unit, 49...Low-pass filter, Q1 to Q6...Semiconductor switches, D1 to D6...Diodes.

Claims

1. A motor control device for controlling a motor by switching between a plurality of control modes, including at least a vector control mode and a voltage phase control mode, comprising: a magnetic flux amplitude calculation unit that calculates a magnetic flux amplitude value based on the magnetic flux value of the motor; a magnetic flux command amplitude calculation unit that calculates a magnetic flux command amplitude value based on the magnetic flux command value of the motor; a lower limit unit that sets a lower limit on the magnetic flux amplitude value based on the magnetic flux command amplitude value; and an integrator initial value calculation unit that sets an initial value for an integrator for performing feedback control in the vector control mode and the voltage phase control mode, wherein when switching the control mode, the lower limit unit limits the lower limit of the magnetic flux amplitude value to the magnetic flux command amplitude value if the magnetic flux amplitude value is less than or equal to the magnetic flux command amplitude value.

2. A motor control device according to claim 1, wherein the integrator initial value calculation unit sets the initial value of the integrator based on the magnetic flux amplitude value after limitation by the lower limit unit.

3. A motor control device according to claim 1, comprising a low-pass filter that reduces components with frequencies higher than a predetermined cutoff frequency, wherein the magnetic flux command amplitude calculation unit calculates a magnetic flux command amplitude value based on the magnetic flux command value of the motor via the low-pass filter.

4. A motor control device according to claim 1, characterized in that the vector control mode is a vector control mode that controls the current using an inverse model of the motor based on magnetic flux.

5. A motor control method for controlling a motor by switching between a plurality of control modes, including at least a vector control mode and a voltage phase control mode, comprising: (a) a step of calculating a magnetic flux amplitude value based on the magnetic flux value of the motor; (b) a step of calculating a magnetic flux command amplitude value based on the magnetic flux command value of the motor; (c) a step of setting a lower limit on the magnetic flux amplitude value calculated in step (a) based on the magnetic flux command amplitude value calculated in step (b); and (d) a step of setting an initial value for an integrator for performing feedback control in the vector control mode and the voltage phase control mode, wherein when switching the control mode, in step (c), if the magnetic flux amplitude value is less than or equal to the magnetic flux command amplitude value, the lower limit of the magnetic flux amplitude value is limited to the magnetic flux command amplitude value.

6. A motor control method according to claim 5, characterized in that in step (d), the initial value of the integrator is set based on the magnetic flux amplitude value after the limitation in step (c).

7. A motor control method according to claim 5, characterized in that, in step (b), a magnetic flux command amplitude value is calculated based on the magnetic flux command value of the motor through a low-pass filter that reduces components with frequencies higher than a predetermined cutoff frequency.

8. A motor control method according to claim 5, characterized in that the vector control mode is a vector control mode that controls the current using an inverse model of the motor based on magnetic flux.

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