Motor control device

Abstract

To provide a motor control device capable of estimating a rotor position using high-frequency current while suppressing motor noise.SOLUTION: In a motor control device 100a, a position estimator 32, a PLL controller 31, and an axis error calculator 30 estimate the position of a rotor that a motor M has based on a high-frequency current generated when a high-frequency voltage is applied to the motor M. A high-frequency voltage command value generator 43 applies a high-frequency voltage intermittently to the motor. For example, the high-frequency voltage command value generator 43 sets a period in which no high-frequency voltage is applied to the motor at predetermined intervals. The high-frequency voltage command value generator 43 also sets, for example, a period in which no high-frequency voltage is applied to the motor every predetermined period of the high-frequency voltage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a motor control device. [Background technology]

[0002] One technique for estimating the rotor position in sensorless vector control for AC motors involves applying a high-frequency voltage that does not contribute to torque generation to the motor and estimating the rotor position using the high-frequency component (hereinafter sometimes referred to as "high-frequency current") contained in the detected current. In this technique, the rotor position is estimated based on a common-mode current vector that rotates in the same direction as the high-frequency magnetic flux vector generated in response to the application of the high-frequency voltage, and a mirror-mode current vector that rotates in the opposite direction to the high-frequency magnetic flux vector (Patent Document 1). Hereinafter, the common-mode current vector and the mirror-mode current vector will be collectively referred to as "common-mode mirror-mode current vector". [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2002-171799 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, when high-frequency current flows through a motor, noise is generated.

[0005] Therefore, this disclosure proposes a technology that can estimate the rotor position using high-frequency current while suppressing motor noise. [Means for solving the problem]

[0006] The motor control device of this disclosure includes an estimator and an application unit. The estimator estimates the position of the rotor of the motor based on the high-frequency current generated when a high-frequency voltage is applied to the motor. The application unit intermittently applies the high-frequency voltage to the motor. [Effects of the Invention]

[0007] According to this disclosure, the rotor position can be estimated using high-frequency current while suppressing motor noise. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows an example of the configuration of a motor control device according to Embodiment 1 of the present disclosure. [Figure 2] Figure 2 shows an example of the configuration of the noise reduction command generator in Embodiment 1 of this disclosure. [Figure 3] Figure 3 shows an example of the operation of the high-frequency voltage command value generator of Embodiment 1 of this disclosure. [Figure 4] Figure 4 is a diagram illustrating the noise reduction effect of Embodiment 1 of this disclosure. [Figure 5] Figure 5 is a diagram illustrating the noise reduction effect of Embodiment 1 of this disclosure. [Figure 6] Figure 6 shows an example of the configuration of the drive component removal filter in Embodiment 1 of this disclosure. [Figure 7] Figure 7 shows an example of the configuration of the axis error calculator in Embodiment 1 of this disclosure. [Figure 8] Figure 8 shows an example configuration of the in-phase mirror-phase current vector generator of Embodiment 1 of this disclosure. [Figure 9] Figure 9 shows an example of the operation of the count calculator, command generator, and high-frequency voltage command value generator of Embodiment 2 of this disclosure. [Figure 10] Figure 10 is a diagram illustrating the noise reduction effect of Embodiment 2 of this disclosure. [Figure 11] Figure 11 shows an example of the operation of the count calculator, command generator, and high-frequency voltage command value generator of Embodiment 3 of this disclosure. [Figure 12] Figure 12 is a diagram illustrating the noise reduction effect of Embodiment 3 of this disclosure. [Figure 13] Figure 13 shows an example of the operation of the high-frequency voltage command value generator in Embodiment 4 of this disclosure. [Figure 14] Figure 14 shows an example of the configuration of the axis error calculator in Embodiment 5 of this disclosure. [Figure 15] Figure 15 shows an example of the configuration of a motor control device according to Embodiment 6 of the present disclosure. [Figure 16] Figure 16 shows an example of the configuration of a motor control device according to Embodiment 7 of this disclosure. [Modes for carrying out the invention]

[0009] The embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, the same parts will be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0010] This disclosure describes a motor control device that performs position sensorless vector control of a permanent magnet synchronous motor (PMSM) that drives a compressor as an example. However, the disclosed technology is broadly applicable to motor control devices that estimate the rotor position using magnetic salient polarity for motors having magnetic salient polarity.

[0011] [Example 1] <Motor control device configuration> Figure 1 shows an example configuration of a motor control device according to Embodiment 1 of the present disclosure. In Figure 1, the motor control device 100a includes subtractors 11, 18, 19, a speed controller 12, adders 21, 22, 44, 45, a current command value calculator 14, a current controller 20, a dq / u,v,w converter 23, a PWM (Pulse Width Modulation) modulator 24, and an IPM (Intelligent Power Module) 25. The IPM 25 is connected to a motor M. An example of a motor M is a PMSM.

[0012] Furthermore, the motor control device 100a includes a shunt resistor 26, current sensors 27a and 27b, and a 3φ current calculator 28. However, the motor control device 100a only needs to have either the shunt resistor 26 or the current sensors 27a and 27b.

[0013] Furthermore, the motor control device 100a includes a u,v,w / dq converter 29, an axis error calculator 30, a PLL (Phase Locked Loop) controller 31, a position estimater 32, a 1 / Pn processor 33, and a decoupling controller 36.

[0014] Furthermore, the motor control device 100a includes a high-frequency voltage command value generator 43, a Pn processor 46, a drive component removal filter 61, a noise reduction command generator 71, a high-frequency current subtractor 41, and a phase generator 42. The high-frequency current subtractor 41 includes subtractors 41a and 41b.

[0015] The subtractor 11 receives the mechanical angular velocity command value ωm from an external source (e.g., a higher-level controller) to the motor control device 100a. * The angular velocity error Δω is calculated by subtracting the current estimated angular velocity, which is the machine angle estimated angular velocity ωm, output from the 1 / Pn processor 33. Here, the machine angle command value ωm * This is a command value determined based on the desired rotational speed of motor M.

[0016] The speed controller 12 sets a torque command value T such that the angular velocity error Δω approaches 0. * Generates.

[0017] The current command value calculator 14 calculates the torque command value T * The d-axis current command value Id on the dq coordinate axis * and q-axis current command value Iq * Distribute it to them.

[0018] The subtractor 18 subtracts the high-frequency removed d-axis current Idm output from the high-frequency current subtractor 41 from the d-axis current command value Id *By subtracting from, the d-axis current command value Id * and the high-frequency removed d-axis current Idm, the d-axis current error Id_diff, which is the error therebetween, is calculated. The subtracter 19 subtracts the high-frequency removed q-axis current Iqm output from the high-frequency current subtracter 41 from the q-axis current command value Iq * to calculate the q-axis current error Iq_diff, which is the error between the q-axis current command value Iq * and the high-frequency removed q-axis current Iqm.

[0019] The current controller 20 calculates a temporary d-axis voltage command value Vdt by performing PI (Proportional Integral) control based on the input d-axis current error Id_diff. Also, the current controller 20 calculates a temporary q-axis voltage command value Vqt by performing PI control based on the input q-axis current error Iq_diff.

[0020] The decoupling controller 36 generates a d-axis decoupling voltage command value Vda for compensating the temporary d-axis voltage command value Vdt based on the electrical angular velocity command value ωe output from the Pn processor 46 * and the d-axis current command value Id output from the current command value calculator 14 * . Also, the decoupling controller 36 generates a q-axis decoupling voltage command value Vqa for compensating the temporary q-axis voltage command value Vqt based on the electrical angular velocity command value ωe output from the Pn processor 46 * and the q-axis current command value Iq output from the current command value calculator 14 * . The d-axis decoupling voltage command value Vda and the q-axis decoupling voltage command value Vqa are decoupling compensation values for canceling the interference between the d-q coordinate axes by feedforward.

[0021] Adder 21 calculates the d-axis drive voltage command value Vdm by adding the d-axis decoupling voltage command value Vda to the provisional d-axis voltage command value Vdt. Adder 22 calculates the q-axis drive voltage command value Vqm by adding the q-axis decoupling voltage command value Vqa to the provisional q-axis voltage command value Vqt. As a result, the d-axis drive voltage command value Vdm and the q-axis drive voltage command value Vqm are obtained, in which interference between the d and q coordinate axes is canceled out by feedforward.

[0022] The dq / u,v,w converter 23 receives the two-phase d-axis voltage command value Vd from the adders 44 and 45. * and q-axis voltage command value Vq * Based on the electrical angular phase θe output from the position estimator 32, the three-phase U-phase output voltage command value Vu * V-phase output voltage command value Vv * and W-phase output voltage command value Vw * Convert to this. The electrical angular phase θe output from the position estimator 32 indicates the current rotor position of the motor M.

[0023] The PWM modulator 24 controls the U-phase output voltage command value Vu * V-phase output voltage command value Vv * W-phase output voltage command value Vw * Based on the PWM carrier signal, a 6-phase PWM signal is generated, and the generated 6-phase PWM signal is output to the IPM25.

[0024] The IPM25 generates three AC voltages (U-phase, V-phase, and W-phase) from a DC voltage Vdc based on the six-phase PWM signal output from the PWM modulator 24, and applies these three AC voltages to the U-phase, V-phase, and W-phase of the motor M.

[0025] The 3φ current calculator 28 calculates the U-phase current Iu, V-phase current Iv, and W-phase current Iw (i.e., the current flowing through the windings of the motor M) of the motor M from the 6-phase PWM switching information output from the PWM modulator 24 and the detected bus current when the bus current is detected using a single-shunt method with a shunt resistor 26. Alternatively, when the U-phase current and V-phase current are detected by the current sensors 27a and 27b, the 3φ current calculator 28 calculates the remaining W-phase current Iw based on Kirchhoff's law "Iu + Iv + Iw = 0". The 3φ current calculator 28 outputs the phase currents Iu, Iv, and Iw of each phase to the u,v,w / dq converter 29.

[0026] The u,v,w / dq converter 29 converts the three-phase U-phase current Iu, V-phase current Iv, and W-phase current Iw into two-phase d-axis current Id and q-axis current Iq based on the electrical angular phase θe output from the position estimator 32.

[0027] The PLL controller 31 calculates the electrical angular velocity ωe, which is the current estimated angular velocity of the motor M, based on the axis error Δθ output from the axis error calculator 30.

[0028] The position estimator 32 estimates the electrical angular phase θe based on the estimated electrical angular velocity ωe.

[0029] The 1 / Pn processor 33 calculates the estimated mechanical angular velocity ωm by dividing the estimated electrical angular velocity ωe by the number of pole pairs Pn of the motor M.

[0030] The Pn processor 46 processes the mechanical angular velocity command value ωm * Multiply the number of pole pairs Pn of motor M by the electrical angular velocity command value ωe * Calculate.

[0031] The high-frequency voltage command value generator 43 generates the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * This generates the following. In the following, the d-axis high-frequency voltage command value and the q-axis high-frequency voltage command value may be collectively referred to as the "high-frequency voltage vector".

[0032] The phase generator 42 generates a high-frequency voltage with an angular frequency (hereinafter sometimes referred to as "high-frequency angular frequency") ωh * By integrating over the range "0≦ωht≦2π", the high-frequency phase ωht, which is the phase of the high-frequency voltage vector, is generated. High-frequency angular frequency ωh * This is input to the motor control device 100a from an external source (for example, a higher-level controller).

[0033] The high-frequency voltage command value generator 43 receives the application method command signal_noise_method, the high-frequency phase ωht, and the high-frequency voltage amplitude command value Vh from an external source (e.g., a higher-level controller) to the motor control device 100a. * Based on this, the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * Generates a high-frequency voltage vector Vdh. * ,Vqh * This is generated to produce a high-frequency current used for rotor position estimation and does not contribute to torque generation for rotor position estimation. In other words, the high-frequency current used for rotor position estimation is the high-frequency voltage vector Vdh to the motor M. * ,Vqh * It occurs in response to the application of [something].

[0034] The adder 44 controls the d-axis drive voltage command value Vdm and the d-axis high-frequency voltage command value Vdh * By adding these together, the d-axis voltage command value Vd * The adder 45 calculates the q-axis drive voltage command value Vqm and the q-axis high-frequency voltage command value Vqh. * By adding these together, the q-axis voltage command value Vq * The following is calculated. In the following, the d-axis drive voltage command value Vdm and the q-axis drive voltage command value Vqm may be collectively referred to as "drive voltage command value Vm".

[0035] The drive component removal filter 61 controls the mechanical angular velocity command value ωm * and high-frequency angular frequency ωh *Based on this, the high-frequency d-axis current Idh is extracted from the d-axis current Id by removing components other than the high-frequency component from the d-axis current Id. In addition, the drive component removal filter 61 is used with respect to the mechanical angular velocity command value ωm * and high-frequency angular frequency ωh * Based on this, the high-frequency q-axis current Iqh is extracted from the q-axis current Iq by removing components other than the high-frequency component from the q-axis current Iq. Hereafter, components other than the high-frequency component may be referred to as "non-high-frequency current". Non-high-frequency current is the current component generated in conjunction with the driving of the motor M. Hereafter, the high-frequency d-axis current Idh and the high-frequency q-axis current Iqh may be collectively referred to as "high-frequency current Ih".

[0036] The axis error calculator 30 receives the signal_noise_method command, the high-frequency d-axis current Idh, the high-frequency q-axis current Iqh, and the high-frequency angular frequency ωh from the noise reduction command generator 71. * Based on this, the axis error Δθ (the difference between the actual axis of rotation and the estimated axis of rotation) is calculated. In other words, the axis error calculator 30 calculates the high-frequency voltage vector Vdh * ,Vqh * Using the high-frequency current vector generated in response to the application of the current, the axis error Δθ, which is the discrepancy between the dq coordinate axis and the estimated coordinate axis of the dq coordinate axis, is calculated.

[0037] In other words, the position estimator 32, the PLL controller 31, and the axis error calculator 30 estimate the position of the rotor of the motor M based on the high-frequency current generated when a high-frequency voltage is applied to the motor M.

[0038] Subtractor 41a calculates the high-frequency removed d-axis current Idm by subtracting the high-frequency d-axis current Idh from the d-axis current Id. Subtractor 41b calculates the high-frequency removed q-axis current Iqm by subtracting the high-frequency q-axis current Iqh from the q-axis current Iq. In other words, subtractor 41 extracts the drive current of the motor M from the d-axis current Id and q-axis current Iq by subtracting the high-frequency current Ih extracted by the drive component removal filter 61 from the d-axis current Id and q-axis current Iq.

[0039] <Configuration of the noise reduction command generator> Figure 2 shows an example of the configuration of a noise reduction command generator according to Embodiment 1 of this disclosure. The motor control device of this embodiment intermittently applies a high-frequency voltage to the motor M. In Figure 2, the noise reduction command generator 71 has a count calculator 71a and a command generator 71b. The noise reduction command generator 71 sets the timing for applying a high-frequency voltage to estimate the rotor position of the motor M (hereinafter sometimes referred to as "position estimation") and the timing for not applying a high-frequency voltage to reduce noise.

[0040] The count calculator 71a calculates a noise reduction count signal_count based on the high-frequency phase ωht at each predetermined control cycle. Here, the high-frequency phase ωht is repeatedly generated with a cycle of 0 to 2π. The count calculator 71a determines that one cycle of the high-frequency phase ωht has elapsed when the high-frequency phase ωht generated in the current control cycle is less than the high-frequency phase ωht_old generated in the previous control cycle, that is, when the high-frequency phase ωht reaches 2π and returns to 0, and increments the noise reduction count signal_count by 1 (hereinafter sometimes referred to as "incrementing"). Here, when an arbitrary period is set, the noise reduction command generator 71 is set with a number of intervals (hereinafter sometimes referred to as "intervals with application") X in which the high-frequency voltage is applied to the motor M (hereinafter sometimes referred to as "intervals with application") and a number of intervals (hereinafter sometimes referred to as "intervals without application") Y in which the high-frequency voltage is not applied to the motor M (hereinafter sometimes referred to as "intervals without application"), with one interval of the high-frequency phase ωht being considered as one interval. The count calculator 71a increments the noise reduction count signal_count from 1 to X+Y, and resets the noise reduction count signal_count to 1 when it reaches X+Y.

[0041] The command generator 71b generates the signal_noise_method command based on the noise reduction count signal_count. The signal_noise_method command indicates whether or not a high-frequency voltage is applied. When the noise reduction count signal_count is less than or equal to X, the command generator 71b sets the signal_noise_method command to "SIGNAL_ON (0)", while when the noise reduction count signal_count is greater than X, it sets the signal_noise_method command to "SIGNAL_OFF (1)".

[0042] <Operation of the High-Frequency Voltage Command Value Generator> Figure 3 shows an example of the operation of the high-frequency voltage command value generator in Embodiment 1 of this disclosure. Figure 3 shows an example where one period of the high-frequency phase ωht is considered one interval, and the number of applied intervals X is set to "3", while the number of unapplied intervals Y is set to "1". Therefore, the count calculator 71a increments the noise reduction count signal_count from 1 to 4 for each period of the high-frequency phase ωht, and resets the noise reduction count signal_count to 1 when it reaches 4. In addition, the command generator 71b sets the application method command signal_noise_method to "SIGNAL_ON(0)" when the noise reduction count signal_count is 3 or less, while setting the application method command signal_noise_method to "SIGNAL_OFF(1)" when the noise reduction count signal_count is greater than 3.

[0043] The high-frequency voltage command value generator 43 receives the application method command signal_noise_method as input. The high-frequency voltage command value generator 43 generates the high-frequency voltage amplitude command value Vh according to the application method command signal_noise_method, as follows. * Based on the high-frequency phase ωht, the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * Generates.

[0044] When the application method command signal_noise_method input from the noise reduction command generator 71 is set to “SIGNAL_ON(0)”, the high-frequency voltage command value Vdh on the d axis is calculated according to equation (1). * and the q-axis high-frequency voltage command value Vqh * Generates.

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[0045] On the other hand, when the application method command signal_noise_method input from the noise reduction command generator 71 is set to “SIGNAL_OFF(1)”, the high-frequency voltage command value Vdh of the d axis is calculated according to equation (2) in the high-frequency voltage command value generator 43. * and the q-axis high-frequency voltage command value Vqh * This generates the d-axis high-frequency voltage command value Vdh. In other words, when the application method command signal_noise_method is set to "SIGNAL_OFF(1)", the high-frequency voltage command value generator 43 generates the d-axis high-frequency voltage command value Vdh. * and the q-axis high-frequency voltage command value Vqh * To make it 0, no high-frequency voltage is applied to motor M.

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[0046] Therefore, when the number of application intervals X is set to "3" and the number of non-application intervals Y is set to "1", as shown in Figure 3, the high-frequency voltage is applied to the motor M in three intervals from the first period T1 to the third period T3, and then not applied to the motor M in one interval of the fourth period T4. Similarly thereafter, the high-frequency voltage is applied to the motor M in three intervals from the fifth period T5 to the seventh period T7, and then not applied to the motor M in one interval of the eighth period T8. Furthermore, the high-frequency voltage is applied to the motor M in three intervals from the ninth period T9 to the eleventh period T11. In this way, the high-frequency voltage command value generator 43 intermittently applies the high-frequency voltage to the motor M. For example, as shown in Figure 3, the high-frequency voltage command value generator 43 provides intervals in which the high-frequency voltage is not applied to the motor M at predetermined time intervals corresponding to three periods of the high-frequency phase ωht. Furthermore, as shown in Figure 3, one period of the high-frequency phase ωht corresponds to one period of the high-frequency voltage. Therefore, the high-frequency voltage command value generator 43 may, for example, provide a section where the high-frequency voltage is not applied to the motor M every three periods of the high-frequency voltage, as shown in Figure 3. Note that the larger the number of applied-voltage sections X is set relative to the number of unapplied-voltage sections Y, the higher the accuracy of position estimation and the less unstable the control of the motor M becomes. On the other hand, the larger the number of unapplied-voltage sections Y is set relative to the number of unapplied-voltage sections X, the greater the effect of suppressing noise. Therefore, the number of applied-voltage sections X and the number of unapplied-voltage sections Y should be set to appropriate values ​​in advance through experiments or other means so as to satisfy the stability of control and the effect of suppressing noise.

[0047] In the following, the conventional application method, that is, the application method in which the high-frequency voltage is continuously applied to the motor M without a change in the phase of the high-frequency voltage, will be referred to as "First Application Method NCA". In the following, the application method of Example 1, that is, the application method in which the high-frequency voltage is intermittently applied to the motor M, will be referred to as "Second Application Method NCB".

[0048] Here, when the second application method NCB is used as the method for applying high-frequency voltage, sidebands are generated. The frequency of the sidebands when the second application method NCB is used is the high-frequency current frequency fh * Based on “fh * ±fh *It is expressed as / (X+Y)''.

[0049] As an example, high-frequency current frequency fh * When the frequency is 250 Hz, and the first application method NCA is used as the method for applying the high-frequency voltage, the frequency spectrum of the noise generated by the application of the high-frequency voltage (hereinafter sometimes referred to as the "noise spectrum") appears only at 250 Hz, as shown in Figure 4. Figure 4 is a diagram used to explain the noise reduction effect of Embodiment 1 of this disclosure.

[0050] In contrast, high-frequency current frequency fh * When the frequency is 250 Hz, if the second application method NCB is used as the method for applying the high-frequency voltage, as shown in Figure 5, the sideband with the largest noise spectrum appears at 250 Hz ± 62.5 Hz, while the time-averaged noise level at 250 Hz generated by the application of the high-frequency voltage can be reduced compared to when the first application method NCA is used (Figure 4). Figure 5 is a diagram for explaining the noise reduction effect of Embodiment 1 of this disclosure.

[0051] By providing a no-voltage section in this manner, the time-averaged noise level of the motor M can be reduced, thereby suppressing the noise of the motor M.

[0052] <Configuration of the drive component removal filter> Figure 6 shows an example configuration of the drive component removal filter of Embodiment 1 of the present disclosure. In Figure 6, the drive component removal filter 61 includes a high-pass filter 61a, a low-pass filter 61b, a notch filter 61c, and a filter constant calculator 61d.

[0053] Here, the in-phase mirror-phase current vector generator 301 of the axis error calculator 30, which will be described later, functions as a bandpass filter, and in a bandpass filter, the wider the pass frequency bandwidth, the faster the filter's response speed.

[0054] However, due to the sampling rate based on the carrier frequency in the motor control device 100a, it can be difficult to sufficiently separate the frequency band of non-high frequency currents from the frequency band of high frequency currents (Reason 1). For example, since the calculation of the axis error is performed for each period of the carrier signal, the high frequency current frequency fh * If the high frequency (fh) is close to the carrier frequency, the number of samples per period of the high-frequency current decreases, reducing the accuracy of position estimation. Therefore, the high-frequency current frequency fh * It is preferable that the frequency is sufficiently low relative to the carrier frequency (for example, a frequency of 1 / 20th of the carrier frequency).

[0055] Furthermore, since the magnitude of the voltage and current of the drive component that contributes to torque generation changes depending on the driving conditions of the motor M (load, rotational speed, etc.), even under conditions where the voltage and current of the drive component are at their maximum, the drive component frequency band (i.e., the high-frequency current frequency fh) is sufficiently removed to the extent that the current of the drive component (i.e., the non-high-frequency current) is sufficiently removed. * It is necessary to guarantee the attenuation of frequency bands other than the specified band (Reason 2).

[0056] Furthermore, as the motor is driven, a high-frequency current component is generated, mainly due to the motor's cogging torque, corresponding to the motor's rotational speed. Hereafter, the high-frequency current component generated due to the motor's cogging torque will be referred to as the "cogging current." The order of the cogging current frequency is determined by the number of poles on the motor M's rotor (hereinafter sometimes referred to as the "number of rotor poles") and the number of slots on the motor M (hereinafter sometimes referred to as the "number of motor slots"). For example, if motor M is a P-pole, S-slot motor, a cogging current with a frequency equal to the least common multiple of P and S is generated. In addition, cogging currents with frequencies equal to half, twice, three times, ..., n times the least common multiple of P and S are also generated. For example, if motor M is a 6-pole, 9-slot motor, in addition to the 18th-order frequency, which is the least common multiple of 6 and 9, cogging currents with frequencies equal to half the least common multiple of 6 and 9 (the 9th-order frequency), and 18 × n-order frequencies such as the 36th, 54th, ... are generated. Such cogging currents reduce the accuracy of position estimation, so it is necessary to ensure an attenuation level that can sufficiently eliminate the cogging current (Reason 3).

[0057] Furthermore, for the reasons 1, 2, and 3 above, it becomes necessary to narrow the passband of the common-mode mirror-phase current vector generator 301 as a bandpass filter, which slows down the filter response speed of the common-mode mirror-phase current vector generator 301.

[0058] Therefore, in order to input the high-frequency d-axis current Idh and high-frequency q-axis current Iqh to the in-phase mirror-phase current vector generator 301, the drive component removal filter 61 has a high-pass filter 61a, a low-pass filter 61b, a notch filter 61c, and a filter constant calculator 61d, as shown in Figure 6. When the high-frequency d-axis current Idh and high-frequency q-axis current Iqh are input to the in-phase mirror-phase current vector generator 301, the current input to the in-phase mirror-phase current vector generator 301 becomes only the high-frequency current generated by the high-frequency voltage for rotor position estimation. In this way, by combining the high-pass filter 61a, the low-pass filter 61b, and the notch filter 61c to form a band-pass filter, it is possible to widen the passband frequency of the in-phase mirror-phase current vector generator 301 as a band-pass filter, and thus the filter response speed can be increased compared to when a band-pass filter with a narrow passband frequency is used as the in-phase mirror-phase current vector generator 301.

[0059] In Figure 6, the high-pass filter 61a removes the drive current component (hereinafter sometimes referred to as "drive current") Im, which contributes to the torque generation of the motor M, from the d-axis current Id and the q-axis current Iq, thereby obtaining the drive current-removed d-axis current Id1 and drive current-removed q-axis current Iq1. The drive current Im is the current component generated when the motor M is driven by the drive voltage command value Vm. For example, the passband of the high-pass filter 61a is set to the mechanical angular velocity command value ωm * A sufficiently large frequency (for example, the mechanical angular velocity command value ωm) * It is preferable to use a frequency band with a frequency four times or more greater than that of [the specified frequency].

[0060] When the drive current Im is removed by the high-pass filter 61a, a phase shift occurs in the high-frequency currents (drive current removal d-axis current Id1 and drive current removal q-axis current Iq1). Equation (3) shows the first-order phase characteristic θhigh of the high-pass filter 61a. In equation (3), "HIGH_a0" is the filter constant of the high-pass filter 61a. From equation (3), the frequency fh of the high-frequency current generated in the high-pass filter 61a is given by... *The amount of phase shift in the band can be determined.

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[0061] On the other hand, the high-frequency current frequency fh of the low-pass filter 61b * The first-order phase characteristic θlow of the band is given by equation (4). In equation (4), "LOW_a0" is the filter constant of the low-pass filter 61b.

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[0062] Therefore, the filter constant calculator 61d calculates the high-frequency angular frequency ωh according to equations (5) and (6). * Based on the filter constant HIGH_a0 of the high-pass filter 61a, the filter constant LOW_a0 of the low-pass filter 61b is calculated. The filter constant LOW_a0 is the high-frequency angular frequency ωh * It is updated as needed in response to changes. The filter constant LOW_a0 calculated by the filter constant calculator 61d is set in the low-pass filter 61b.

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[0063] The low-pass filter 61b performs filtering on the drive current-removed d-axis current Id1 and drive current-removed q-axis current Iq1 using the filter constant LOW_a0 calculated by the filter constant calculator 61d. This compensates for the phase shift that occurs in the drive current-removed d-axis current Id1 and drive current-removed q-axis current Iq1, and removes high-frequency noise Inoise from the drive current-removed d-axis current Id1 and drive current-removed q-axis current Iq1. High-frequency noise Inoise is generated in a frequency band higher than the frequency of the high-frequency current Ih as the motor M is driven. The low-pass filter 61b outputs the filtered noise-removed d-axis current Id2 and noise-removed q-axis current Iq2 to the notch filter 61c.

[0064] The notch filter 61c obtains high-frequency d-axis current Idh and high-frequency q-axis current Iqh by removing the cogging current at cogging frequency fcog from the noise-removed d-axis current Id2 and noise-removed q-axis current Iq2. The cogging frequency fcog is determined by the least common multiple of the rotor pole number P and the motor slot number S and the mechanical angular velocity command value ωm. * The cogging frequency fcog is calculated by dividing the result of multiplication by 2π, and is set as the center frequency of the attenuation region of the notch filter 61c. The cogging frequency fcog is calculated using the mechanical angular velocity command value ωm * This will be updated as changes occur.

[0065] As described above, the drive component removal filter 61 obtains a high-frequency current Ih by removing non-high-frequency currents from the d-axis current Id and the q-axis current Iq. For example, the drive current Im, high-frequency noise Inoise, and cogging current are non-high-frequency currents, which are current components generated in conjunction with the driving of the motor M.

[0066] <Configuration of the axis error calculator> Figure 7 shows an example configuration of the axis error calculator of Embodiment 1 of this disclosure. The axis error calculator 30a shown in Figure 7 corresponds to the axis error calculator 30 shown in Figure 1. In Figure 7, the axis error calculator 30a includes a common-mode mirror-phase current vector generator 301, a mirror-phase estimator 302, a filter-corrected current estimator 303, and a switch 304. The axis error calculator 30a utilizes the magnetic salient polarity of the motor M and calculates a high-frequency angular frequency ωh * Based on the high-frequency d-axis current Idh and the high-frequency q-axis current Iqh, the axis error Δθ is calculated. Figure 8 shows an example configuration of the in-phase mirror-image current vector generator of Embodiment 1 of this disclosure. In Figure 8, the in-phase mirror-image current vector generator 301 has a sign inverter b11 and D-factor filters b12, b13.

[0067] In Figure 8, the sign inverter b11 has a high-frequency angular frequency ωh * The sign is reversed, and the high-frequency angular frequency after the sign reversal is -ωh * Output to the D factor filter b12.

[0068] The D-factor filters b12 and b13 are filters that separate and extract in-phase and enantiomer components, and the D-factor in the D-factor filters b12 and b13 is defined by equation (7) using the identity matrix I, the skew-symmetric matrix J, and the Laplace operator s.

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[0069] The D-factor filter b12 has a high-frequency angular frequency of -ωh after sign inversion. * Based on this, the common-mode current vector Ihp contained in the high-frequency d-axis current Idh and high-frequency q-axis current Iqh is detected. The common-mode current vector Ihp is the high-frequency voltage vector Vdh * ,Vqh * It rotates in the same direction as the high-frequency magnetic flux vector generated in response to the application of the signal.

[0070] The D-factor filter b13 has a high-frequency angular frequency ωh *Based on this, the mirror phase current vector Ihn contained in the high-frequency d-axis current Idh and high-frequency q-axis current Iqh is detected. The mirror phase current vector Ihn is the high-frequency voltage vector Vdh * ,Vqh * It rotates in the opposite direction to the high-frequency magnetic flux vector generated in response to the application of the signal.

[0071] Here, the D-factor filters b12 and b13 have a frequency response F(s+jωh) for each component of a 2×1 vector, which is a scalar signal. * It functions equivalently to the filter of ). Therefore, by designing F(s) to have low-pass characteristics and applying it to D-factor filters b12 and b13, the D-factor filters b12 and b13 become ωh * This will function as a bandpass filter with a center frequency of . Furthermore, the D-factor filters b12 and b13 have polarity separation characteristics. In other words, the polarity separation bandpass characteristics of the D-factor filters b12 and b13 allow the high-frequency d-axis current Idh and high-frequency q-axis current Iqh to be separated into the common-mode current vector Ihp and the mirror-mode current vector Ihn.

[0072] As described above, the in-phase mirror phase current vector generator 301 calculates the in-phase current vector Ihp and the mirror phase current vector Ihn using high-frequency current, whereas the filter-corrected current estimator 303 calculates the in-phase current vector Ihp and the mirror phase current vector Ihn without using high-frequency current, as follows. The filter-corrected current estimator 303 estimates the in-phase current vector Ihp according to equation (8) and the mirror phase current vector Ihn according to equation (9). In equations (8) and (9), Ld is the d-axis inductance of the motor M, Lq is the q-axis inductance of the motor M, R(2Δθ) is a rotation matrix with a rotation angle of 2Δθ, up(ωht) is a 2×1 unit positive-sequence matrix represented by equation (10), and un(ωht) is a 2×1 unit negative-sequence matrix represented by equation (11). Also, Δθ in equation (9) is a provisional axis error calculated by an extended induced voltage method or the like, which uses the induced voltage generated by the rotation of the motor M to estimate the position. In other words, the filter-corrected current estimator 303 estimates the common-mode current vector Ihp and the mirror-mode current vector Ihn that occur when a high-frequency voltage is applied to the motor, by using theoretical formulas.

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[0073] Here, in the no-applied section, the high-frequency d-axis current Idh and high-frequency q-axis current Iqh do not flow, making it difficult to calculate the common-mode current vector Ihp and mirror-phase current vector Ihn using the common-mode mirror-phase current vector generator 301. Therefore, the switch 304 switches the output source of the common-mode current vector Ihp and mirror-phase current vector Ihn input to the mirror-phase estimator 302 between the common-mode mirror-phase current vector generator 301 and the filter-corrected current estimator 303, according to the application method command signal_noise_method input from the noise reduction command generator 71. When the application method command signal_noise_method is set to "SIGNAL_ON(0)", the switch 304 connects the common-mode mirror-phase current vector generator 301 to the mirror-phase estimator 302, thereby making the output source of the common-mode current vector Ihp and mirror-phase current vector Ihn input to the mirror-phase estimator 302 the common-mode mirror-phase current vector generator 301. On the other hand, when the application method command signal_noise_method is set to “SIGNAL_OFF(1)”, the switch 304 connects the filter-corrected current estimator 303 to the mirror phase estimator 302, thereby making the filter-corrected current estimator 303 the source of the common-mode current vector Ihp and mirror phase current vector Ihn input to the mirror phase estimator 302. In this way, in the applied-current section, the common-mode current vector Ihp and mirror phase current vector Ihn generated by the common-mode mirror phase current vector generator 301 are input to the mirror phase estimator 302, while in the unapplied-current section, the common-mode current vector Ihp and mirror phase current vector Ihn estimated by the filter-corrected current estimator 303 are input to the mirror phase estimator 302. Therefore, even when an unapplied-current section is provided to suppress the noise of the motor M, the common-mode current vector Ihp and mirror phase current vector Ihn can be calculated, preventing the control of the motor M from becoming unstable.

[0074] The mirror phase estimator 302 calculates the axis error Δθ according to equations (12) and (13) using the common-mode current vector Ihp and the mirror phase current vector Ihn input from the common-mode mirror phase current vector generator 301 or the filter-corrected current estimator 303. In other words, the mirror phase estimator 302 calculates the axis error Δθ as the arctangent of the composite vector obtained by vector addition of the common-mode current vector Ihp and the mirror phase current vector Ihn, which have the same norm.

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[0075] Furthermore, the switch 304 may connect the in-phase mirror phase current vector generator 301 to the mirror phase estimator 302 in the section from the time when the application method command signal_noise_method set to “SIGNAL_ON(0)” is input started (hereinafter sometimes referred to as the “start time of the applied-voltage section”) after a predetermined waiting time has elapsed, until the time when the application method command signal_noise_method set to “SIGNAL_OFF(1)” is input started (hereinafter sometimes referred to as the “end time of the applied-voltage section”) (hereinafter sometimes referred to as the “first predetermined section”), and connect the filter correction current estimator 303 to the mirror phase estimator 302 in the section from the end time of the applied-voltage section until a predetermined waiting time has elapsed from the start time of the next applied-voltage section (hereinafter sometimes referred to as the “second predetermined section”). Here, immediately after the application of the high-frequency voltage, the high-frequency current becomes unstable. Therefore, the predetermined waiting time is set to the time until the high-frequency current stabilizes, for example, a time corresponding to one cycle of the high-frequency voltage. In this case, as explained in Figure 3, from the first period T1 to the fifth period T5, the start of the first period T1 and the fifth period T5 correspond to the start of the applied voltage section. Also, the first period T1 and the fifth period T5 correspond to a predetermined waiting time. Furthermore, the end of the first period T1 and the fifth period T5 corresponds to the time when the predetermined waiting time has elapsed. Also, the end of the third period T3 corresponds to the end of the applied voltage section. Furthermore, the second period T2 to the third period T3 becomes the first predetermined section, and the first period T1 and the fourth period T4 to the fifth period T5 become the second predetermined section. By doing this, it is possible to prevent the control of the motor M from becoming unstable in the section immediately after the application of the high-frequency voltage when the high-frequency current is not yet stable.

[0076] The above describes Example 1.

[0077] [Example 2] <Operation of the count calculator, command generator, high-frequency voltage command value generator, and switch> Figure 9 shows an example of the operation of the count calculator, command generator, and high-frequency voltage command value generator in Embodiment 2 of this disclosure. Embodiment 2 differs from Embodiment 1 in that, as shown in Figure 9, there is no no-voltage interval, and the phase of the high-frequency voltage is alternately inverted between a first phase, which is in positive phase, and a second phase, which is inverse phase, which is the opposite phase to the first phase. For example, the amplitude of the high-frequency voltage in the first phase and the amplitude of the high-frequency voltage in the second phase are the same. The differences from Embodiment 1 will be explained below.

[0078] The count calculator 71a calculates the noise reduction count signal_count based on the high-frequency phase ωht. The count calculator 71a determines that one period of the high-frequency phase ωht has elapsed if the high-frequency phase ωht generated in the current control cycle is less than the high-frequency phase ωht_old generated in the previous control cycle, and increments the noise reduction count signal_count. Here, when an arbitrary period is set, the noise reduction command generator 71 is set to invert the phase of the high-frequency voltage every X periods, with one period of the high-frequency phase ωht being considered as one period. The count calculator 71a increments the noise reduction count signal_count from 1 to X, and resets the noise reduction count signal_count to 1 when it reaches X.

[0079] The command generator 71b generates an application method command signal_noise_method based on the noise reduction count signal_count. The application method command signal_noise_method indicates whether the phase of the high-frequency voltage is first phase or second phase. Each time the noise reduction count signal_count reaches X, the command generator 71b switches the setting of the application method command signal_noise_method between "SIGNAL_ON_POS(0)" and "SIGNAL_ON_NEG(1)". That is, if the application method command signal_noise_method is set to "SIGNAL_ON_POS(0)" when the noise reduction count signal_count reaches X, the command generator 71b changes the application method command signal_noise_method from "SIGNAL_ON_POS(0)" to "SIGNAL_ON_NEG(1)". On the other hand, if the noise reduction count signal_count reaches X and the application method command signal_noise_method is set to "SIGNAL_ON_NEG(1)", the command generator 71b changes the application method command signal_noise_method from "SIGNAL_ON_NEG(1)" to "SIGNAL_ON_POS(0)".

[0080] Figure 9 shows an example where one period of the high-frequency phase ωht is defined as one interval, the number of intervals X is set to "3", and the phase of the high-frequency voltage is inverted every three intervals. Therefore, the count calculator 71a increments the noise reduction count signal_count from 1 to 3 for each period of the high-frequency phase ωht, and resets the noise reduction count signal_count to 1 when it reaches 3. In addition, the command generator 71b changes the application method command signal_noise_method, which is set to "SIGNAL_ON_POS(0)", to "SIGNAL_ON_NEG(1)", and changes the application method command signal_noise_method, which is set to "SIGNAL_ON_NEG(1)", back to "SIGNAL_ON_POS(0)" each time the noise reduction count signal_count reaches 3.

[0081] The high-frequency voltage command value generator 43 receives the application method command signal_noise_method as input. The high-frequency voltage command value generator 43 generates the high-frequency voltage amplitude command value Vh according to the application method command signal_noise_method, as follows. * Based on the high-frequency phase ωht, the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * Generates.

[0082] When the application method command signal_noise_method input from the noise reduction command generator 71 is set to “SIGNAL_ON_POS(0)”, the high-frequency voltage command value Vdh on the d axis is calculated according to equation (1). * and the q-axis high-frequency voltage command value Vqh * Generates.

[0083] On the other hand, when the application method command signal_noise_method input from the noise reduction command generator 71 is set to “SIGNAL_ON_NEG(1)”, the high-frequency voltage command value Vdh of the d axis is calculated according to equation (14) in the high-frequency voltage command value generator 43. *and the q-axis high-frequency voltage command value Vqh * is generated. That is, when the application method command signal_noise_method is set to "SIGNAL_ON_NEG(1)", the high-frequency voltage command value generator 43 applies a high-frequency voltage that is in the opposite phase to the high-frequency voltage applied to the motor M when the application method command signal_noise_method is set to "SIGNAL_ON_NEG(1)". [Number]

[0084] Therefore, when the number of intervals X is set to "3", as shown in FIG. 9, after a positive-phase high-frequency voltage is applied to the motor M in three intervals of the first cycle T1 to the third cycle T3, a negative-phase high-frequency voltage is applied to the motor M in three intervals of the fourth cycle T4 to the sixth cycle T6. Also, after a negative-phase high-frequency voltage is applied to the motor M in three intervals of the fourth cycle T4 to the sixth cycle T6, a positive-phase high-frequency voltage is applied to the motor M in three intervals of the seventh cycle T7 to the ninth cycle T9. Thus, the high-frequency voltage command value generator 43 alternately applies, as the high-frequency voltage, a high-frequency voltage of the first phase and a high-frequency voltage that is in the opposite phase to the high-frequency voltage of the first phase to the motor M.

[0085] Hereinafter, the application method of Example 2, that is, the application method in which the high-frequency voltage is continuously applied to the motor M and the phase of the high-frequency voltage is inverted every predetermined time, is denoted as "third application method NCC".

[0086] Here, when the third application method NCC is used as the application method of the high-frequency voltage, sidebands are generated. The frequency of the sidebands when the third application method NCC is used is the high-frequency current frequency fh * based on " * fh * ±fh

[0087] As an example, the high-frequency current frequency fh *When the frequency is 250 Hz, if the third application method NCC is used as the method for applying the high-frequency voltage, as shown in Figure 10, the sideband with the largest noise spectrum appears at 250 Hz ± 41.7 Hz, while the time-averaged noise level at 250 Hz generated by the application of the high-frequency voltage can be reduced compared to when the first application method NCA is used (Figure 4). Figure 10 is a diagram for explaining the noise reduction effect of Embodiment 2 of this disclosure.

[0088] In this way, by alternately providing sections in which a first-phase high-frequency voltage is applied to the motor M and sections in which a second-phase voltage, which has the opposite phase to the first phase, is applied to the motor M, the time-averaged noise level of the motor M can be reduced, thereby suppressing the noise of the motor M. Furthermore, since there are no sections without voltage application, a decrease in the accuracy of position estimation can be prevented.

[0089] Furthermore, even when the application method command signal_noise_method is set to either "SIGNAL_ON_POS(0)" or "SIGNAL_ON_NEG(1)", the switch 304 connects the common-mode mirror phase current vector generator 301 to the mirror phase estimator 302, thereby making the common-mode mirror phase current vector Ihp and mirror phase current vector Ihn input to the mirror phase estimator 302 the source of output for the common-mode mirror phase current vector generator 301.

[0090] Furthermore, the switch 304 may connect the in-phase mirror phase current vector generator 301 to the mirror phase estimator 302 in the section from the time when the application method command signal_noise_method switches between "SIGNAL_ON_POS(0)" and "SIGNAL_ON_NEG(1)" (hereinafter sometimes referred to as the "first phase switching time") until a predetermined waiting time has elapsed, to the next phase switching time (hereinafter sometimes referred to as the "second phase switching time") (hereinafter sometimes referred to as the "third predetermined section"), and connect the filter correction current estimator 303 to the mirror phase estimator 302 in the section from the second phase switching time until a predetermined waiting time has elapsed (hereinafter sometimes referred to as the "fourth predetermined section"). Here, immediately after the phase switching of the high-frequency voltage, the high-frequency current becomes unstable. Therefore, the predetermined waiting time is set to the time until the high-frequency current stabilizes, for example, a time corresponding to one cycle of the high-frequency voltage. In this case, as explained in Figure 9, from the first period T1 to the fifth period T5, the start of the first period T1 and the fourth period T4 correspond to the first phase switching point. Also, the first period T1 and the fourth period T4 correspond to a predetermined waiting time. Furthermore, the end of the first period T1 and the fourth period T4 corresponds to the point when the predetermined waiting time has elapsed. Furthermore, the end of the third period T3 corresponds to the second phase switching point. Furthermore, the second period T2 to the third period T3 becomes the third predetermined section, and the first period T1 and the fourth period T4 to the fifth period T5 become the fourth predetermined section. By doing this, it is possible to prevent the control of the motor M from becoming unstable in the section immediately after the phase switching of the high-frequency voltage when the high-frequency current is not stable.

[0091] The above describes Example 2.

[0092] [Example 3] <Operation of the count calculator, command generator, high-frequency voltage command value generator, and switch> Figure 11 shows an example of the operation of the count calculator, command generator, and high-frequency voltage command value generator in Embodiment 3 of this disclosure. Embodiment 3 differs from Embodiments 1 and 2 in that, as shown in Figure 11, it alternately inverts the phase of the high-frequency voltage between a first phase, which is in positive phase, and a second phase, which is inverse phase, while providing a no-voltage section. In other words, Embodiment 3 is a combination of Embodiments 1 and 2. The differences from Embodiments 1 and 2 will be explained below.

[0093] The count calculator 71a calculates the noise reduction count signal_count based on the high-frequency phase ωht. The count calculator 71a determines that one period of the high-frequency phase ωht has elapsed if the high-frequency phase ωht generated in the current control cycle is less than the high-frequency phase ωht_old generated in the previous control cycle, and increments the noise reduction count signal_count. Here, when an arbitrary period is set, one period of the high-frequency phase ωht is considered as one interval, and the number of intervals without application Y is set in the noise reduction command generator 71 for the number of intervals with application X. The count calculator 71a increments the noise reduction count signal_count from 1 to X+Y, and resets the noise reduction count signal_count to 1 when it reaches X+Y.

[0094] The command generator 71b generates the signal_noise_method application method command based on the noise reduction count signal_count. The signal_noise_method application method command indicates whether or not a high-frequency voltage is applied and whether the phase of the high-frequency voltage is first phase or second phase. When the noise reduction count signal_count is greater than X, the command generator 71b sets the signal_noise_method application method command signal_noise_method to "SIGNAL_OFF(2)". On the other hand, when the noise reduction count signal_count is less than or equal to X, the command generator 71b sets the signal_noise_method application method command signal_noise_method to "SIGNAL_ON_POS(0)" or "SIGNAL_ON_NEG(1)". Furthermore, the command generator 71b switches the setting of the application method command signal_noise_method between "SIGNAL_ON_POS(0)" and "SIGNAL_ON_NEG(1)" each time the noise reduction count signal_count reaches X+Y.

[0095] Figure 11 shows an example where one period of the high-frequency phase ωht is considered one interval, and the number of intervals with application X is set to "3", while the number of intervals without application Y is set to "1". Therefore, the count calculator 71a increments the noise reduction count signal_count from 1 to 4 for each period of the high-frequency phase ωht, and resets the noise reduction count signal_count to 1 when it reaches 4. In addition, the command generator 71b sets the application method command signal_noise_method to "SIGNAL_ON_POS(0)" or "SIGNAL_ON_NEG(1)" when the noise reduction count signal_count is 3 or less, while setting the application method command signal_noise_method to "SIGNAL_OFF(2)" when the noise reduction count signal_count is greater than 3. Furthermore, when the noise reduction count signal_count is 3 or less, the command generator 71b sets the application method command signal_noise_method to "SIGNAL_ON_POS(0)" or "SIGNAL_ON_NEG(1)". However, the application method command signal_noise_method set at this time is alternately set between "SIGNAL_ON_POS(0)" and "SIGNAL_ON_NEG(1)" each time the noise reduction count signal_count is reset to 1.

[0096] The high-frequency voltage command value generator 43 receives the application method command signal_noise_method as input. The high-frequency voltage command value generator 43 generates the high-frequency voltage amplitude command value Vh according to the application method command signal_noise_method, as follows. * Based on the high-frequency phase ωht, the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * Generates.

[0097] When the application method command signal_noise_method input from the noise reduction command generator 71 is set to "SIGNAL_ON_POS(0)", the high-frequency voltage command value generator 43 generates the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * in accordance with Equation (1).

[0098] Also, when the application method command signal_noise_method input from the noise reduction command generator 71 is set to "SIGNAL_ON_NEG(1)", the high-frequency voltage command value generator 43 generates the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * in accordance with Equation (14).

[0099] Also, when the application method command signal_noise_method input from the noise reduction command generator 71 is set to "SIGNAL_OFF(2)", the high-frequency voltage command value generator 43 generates the d-axis high-frequency voltage command value Vdh * and the q-axis high-frequency voltage command value Vqh * in accordance with Equation (2).

[0100] Therefore, when the number of applied intervals X is set to "3" while the number of non-applied intervals Y is set to "1", as shown in FIG. 11, after a positive-phase high-frequency voltage is applied to the motor M in three intervals of the first to third cycles T1 to T3, the high-frequency voltage is not applied to the motor M in one interval of the fourth cycle T4. Also, after a negative-phase high-frequency voltage is applied to the motor M in three intervals of the fifth to seventh cycles T5 to T7, the high-frequency voltage is not applied to the motor M in one interval of the eighth cycle T8. Also, a positive-phase high-frequency voltage is applied to the motor M in three intervals of the ninth to eleventh cycles T9 to T11. Thus, the high-frequency voltage command value generator 43 alternately applies, as the high-frequency voltage, a high-frequency voltage of the first phase and a high-frequency voltage having a phase opposite to that of the high-frequency voltage of the first phase to the motor M while providing non-applied intervals.

[0101] In the following, the application method of Example 3, that is, the application method in which a high-frequency voltage is intermittently applied to the motor M, and in each section in which a high-frequency voltage is applied to the motor, a positive-sequence high-frequency voltage and a negative-sequence high-frequency voltage are alternately applied to the motor M, will be referred to as the "fourth application method NCD".

[0102] Here, when the fourth application method NCD is used as the method for applying high-frequency voltage, sidebands are generated. The frequency of the sidebands when the fourth application method NCD is used is the high-frequency current frequency fh * Based on “fh * ±fh * It can be expressed as / (2(X+Y))”

[0103] As an example, high-frequency current frequency fh * When the frequency is 250 Hz, if the fourth application method NC4 is used as the method for applying the high-frequency voltage, as shown in Figure 12, the sideband with the largest noise spectrum appears at 250 Hz ± 31.25 Hz, while the time-averaged noise level at 250 Hz generated by the application of the high-frequency voltage can be reduced compared to when the first application method NCA is used (Figure 4). Figure 12 is a diagram used to explain the noise reduction effect of Embodiment 3 of this disclosure.

[0104] In this way, by alternately providing sections where a first-phase high-frequency voltage is applied to the motor M, and sections where a second-phase voltage, which is in the opposite phase to the first phase, is applied to the motor M, while also providing a section where no voltage is applied, the time-averaged noise level of the motor M can be reduced, thereby suppressing the noise of the motor M.

[0105] When the application method command signal_noise_method is set to "SIGNAL_ON_POS(0)" or "SIGNAL_ON_NEG(1)", the switch 304 connects the common-mode mirror phase current vector generator 301 to the mirror phase estimator 302, thereby making the common-mode current vector Ihp and mirror phase current vector Ihn input to the mirror phase estimator 302 the source of the output. On the other hand, when the application method command signal_noise_method is set to "SIGNAL_OFF(2)", the switch 304 connects the filter-corrected current estimator 303 to the mirror phase estimator 302, thereby making the common-mode current vector Ihp and mirror phase current vector Ihn input to the mirror phase estimator 302 the source of the output.

[0106] In addition, the switch 304 may, as in Embodiment 1, connect the in-phase mirror phase current vector generator 301 to the mirror phase estimator 302 in the section from when a predetermined waiting time has elapsed from the time when the application method command signal_noise_method set to “SIGNAL_ON_POS(0)” or “SIGNAL_ON_NEG(1)” is input (i.e., the start of the applied voltage section) until when the application method command signal_noise_method set to “SIGNAL_OFF(2)” is input (i.e., the end of the applied voltage section) (hereinafter sometimes referred to as the “fifth predetermined section”), and connect the filter correction current estimator 303 to the mirror phase estimator 302 in the section from the end of the applied voltage section until a predetermined waiting time has elapsed from the start of the next applied voltage section (hereinafter sometimes referred to as the “sixth predetermined section”). Here, immediately after the application of the high-frequency voltage, the high-frequency current becomes unstable. Therefore, the predetermined waiting time is set to the time until the high-frequency current stabilizes, for example, a time corresponding to one cycle of the high-frequency voltage. In this case, as explained in Figure 11, the start of the first period T1 to the fifth period T5 corresponds to the start of the applied voltage section. The first period T1 and the fifth period T5 correspond to the predetermined waiting time. The end of the first period T1 and the fifth period T5 corresponds to the time when the predetermined waiting time has elapsed. The end of the third period T3 corresponds to the end of the applied voltage section. The second period T2 to the third period T3 becomes the fifth predetermined section, and the first period T1 and the fourth period T4 to the fifth period T5 become the sixth predetermined section. This prevents the control of the motor M from becoming unstable in the section immediately after the application of the high-frequency voltage when the high-frequency current is not yet stable.

[0107] Furthermore, the filter-corrected current estimator 303 may calculate the common-mode current vector Ihp and the mirror phase current vector Ihn based on the next high-frequency voltage applied to the motor M, whichever is applied next between the first-phase high-frequency voltage and the second-phase high-frequency voltage, during the no-voltage-applied-current-pass interval. By doing so, the changes in the common-mode current vector Ihp and the mirror phase current vector Ihn input to the mirror phase estimator 302 at the start of the next voltage-applied-current-pass interval are reduced, thereby preventing the control of the motor M from becoming unstable.

[0108] The above describes Example 3.

[0109] [Example 4] <Operation of the High-Frequency Voltage Command Value Generator> Figure 13 shows an example of the operation of the high-frequency voltage command value generator in Embodiment 4 of this disclosure. In Embodiment 4, as shown in Figure 13, at the end of the applied voltage interval, the d-axis high-frequency voltage command value Vdh * The q-axis high-frequency voltage command value Vqh is better than the q-axis high-frequency voltage command value Vqh * The difference from Example 3 is that the generation period is one-quarter longer. The differences from Example 3 will be explained below.

[0110] When the application method command signal_noise_method input from the noise reduction command generator 71 is set to “SIGNAL_OFF(2)”, the high-frequency voltage command value Vdh on the d axis is calculated according to equation (2) in the high-frequency voltage command value generator 43. * and the q-axis high-frequency voltage command value Vqh * The high-frequency voltage command value generator 43 generates the q-axis high-frequency voltage command value Vqh according to equation (1) or equation (14) for a period of one-quarter of a period from the end of the applied voltage interval. * The generation of the high-frequency voltage command value Vqh continues. Specifically, when the application method command signal_noise_method was set to "SIGNAL_ON_POS(0)" in the immediately preceding applied voltage interval, the high-frequency voltage command value Vqh of the q axis is generated according to equation (1). *The generation continues, and if the application method command signal_noise_method was set to “SIGNAL_ON_NEG(1)” in the immediately preceding applied section, the q-axis high-frequency voltage command value Vqh is determined according to equation (14). * Continue generating.

[0111] Therefore, when the number of applied intervals X is set to "3" and the number of unapplied intervals Y is set to "1", as shown in Figure 13, a positive-sequence high-frequency voltage is applied to the motor M in three intervals from the first period T1 to the third period T3, and then no high-frequency voltage is applied to the motor M in one interval, the fourth period T4. Also, an inverse-sequence high-frequency voltage is applied to the motor M in three intervals from the fifth period T5 to the seventh period T7, and then no high-frequency voltage is applied to the motor M in one interval, the eighth period T8. Furthermore, a positive-sequence high-frequency voltage is applied to the motor M in three intervals from the ninth period T9 to the eleventh period T11. However, in the unapplied intervals of the fourth period T4 and the eighth period T8, for a period of one-quarter of a cycle from the start of the unapplied interval (i.e., the end of the applied interval), only the q-axis high-frequency voltage is applied to the motor M, out of the d-axis high-frequency voltage and q-axis high-frequency voltage.

[0112] By doing so, as shown in Figure 13, both the high-frequency d-axis current Idh and the high-frequency q-axis current Iqh can be kept near zero in the no-voltage section, thereby suppressing abrupt changes in the current input to the current controller 20 and preventing the control of the motor M from becoming unstable.

[0113] Furthermore, at the end of the applied voltage section, the d-axis high-frequency voltage command value Vdh * The q-axis high-frequency voltage command value Vqh is better than the q-axis high-frequency voltage command value Vqh * The point of generating it with a period one-quarter longer may also be applied to Example 1.

[0114] The above describes Example 4.

[0115] [Example 5] <Configuration of the axis error calculator> Figure 14 shows an example of the configuration of the axis error calculator in Embodiment 5 of this disclosure. The axis error calculator 30b shown in Figure 14 corresponds to the axis error calculator 30 shown in Figure 1. In Figure 14, the axis error calculator 30b includes a common-mode mirror phase current vector generator 301, a mirror phase estimator 302, a filter correction current estimator 305, and a switch 304. The differences from Embodiment 1 will be described below.

[0116] The filter-corrected current estimator 305 estimates the common-mode current vector Ihp according to equation (15) and the mirror phase current vector Ihn according to equation (16). Here, the filter-corrected current estimator 305 calculates the common-mode current vector Ihp and the mirror phase current vector Ihn for each period of the high-frequency voltage, and in equations (15) and (16), Ihp peak Ihn is the peak value of the in-mode current vector Ihp in the previous period. peak θi is the peak value of the mirror phase current vector Ihn in the previous period. dp is the current phase. Also, up(ωht+θi dp ) is a 2×1 identity positive-sequence matrix represented by equation (17), un(ωht+θi dp ) is a 2 × 1 unit inverse phase matrix represented by equation (18). Also, Δθ in equation (16) is a provisional axis error calculated by an extended induced voltage method or the like, which uses the induced voltage generated by the rotation of the motor M to estimate the position. In other words, the filter-corrected current estimator 303 estimates the common-mode current vector Ihp and mirror-mode current vector Ihn that are generated when a high-frequency voltage is applied to the motor in the current period by using the peak values ​​of the common-mode current vector Ihp and mirror-mode current vector Ihn in the previous period.

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[0117] The above describes Example 5.

[0118] [Example 6] <Motor control device configuration> Figure 15 shows an example configuration of a motor control device according to Embodiment 6 of this disclosure. The motor control device 100b shown in Figure 15 differs from the device 100a of Embodiment 1 in that it has a drive / harmonic separation filter 62 instead of a high-frequency current subtractor 41 and a drive component removal filter 61. The differences from Embodiment 1 will be explained below.

[0119] The drive / harmonic separation filter 62 receives the d-axis current Id and the q-axis current Iq from the u,v,w / dq converter 29. The drive / harmonic separation filter 62, for example, similar to the drive component removal filter 61 in Example 1, uses a high-pass filter, a low-pass filter, and a notch filter to remove non-high-frequency currents from the d-axis current Id to obtain a high-frequency d-axis current Idh, and also removes non-high-frequency currents from the q-axis current Iq to obtain a high-frequency q-axis current Iqh. Furthermore, the drive / harmonic separation filter 62, for example, uses a notch filter to remove the high-frequency d-axis current Idh from the d-axis current Id to obtain a high-frequency removed d-axis current Idm, and also removes the high-frequency removed q-axis current Iqh from the q-axis current Iq to obtain a high-frequency removed q-axis current Iqm. The drive / harmonic separation filter 62 outputs the separated high-frequency d-axis current Idh and high-frequency q-axis current Iqh to the axis error calculator 30, and outputs the separated high-frequency removed d-axis current Idm and high-frequency removed q-axis current Iqm to the subtractors 18 and 19.

[0120] The above describes Example 6.

[0121] [Example 7] <Motor control device configuration> Figure 16 shows an example configuration of a motor control device according to Embodiment 7 of this disclosure. The motor control device 100c shown in Figure 16 differs from the device 100a of Embodiment 1 in that it has a drive current subtractor 48 and a high-frequency current removal filter 63 instead of a high-frequency current subtractor 41 and a drive component removal filter 61. The differences from Embodiment 1 will be explained below.

[0122] The drive current subtractor 48 has subtractors 48a and 48b. The harmonic current rejection filter 63 receives the d-axis current Id and the q-axis current Iq from the u,v,w / dq converter 29. Additionally, the d-axis current Id is input to subtractor 48a from the u,v,w / dq converter 29, and the q-axis current Iq is input to subtractor 48b from the u,v,w / dq converter 29.

[0123] The high-frequency current removal filter 63 obtains a high-frequency removed d-axis current Idm by removing the high-frequency d-axis current Idh from the d-axis current Id using, for example, a notch filter, and also obtains a high-frequency removed q-axis current Iqm by removing the high-frequency q-axis current Iqh from the q-axis current Iq. The high-frequency current removal filter 63 outputs the high-frequency removed d-axis current Idm to subtractors 18 and 48a, and the high-frequency removed q-axis current Iqm to subtractors 19 and 48b.

[0124] Subtractor 48a calculates the high-frequency d-axis current Idh by subtracting the high-frequency removed d-axis current Idm from the d-axis current Id. Subtractor 48b calculates the high-frequency q-axis current Iqh by subtracting the high-frequency removed q-axis current Iqm from the q-axis current Iq.

[0125] The above describes Example 7.

[0126] Examples 6 and 7 describe a method different from Example 1 for separating the d-axis current Id into a high-frequency d-axis current Idh and a high-frequency removed d-axis current Idm, and for separating the q-axis current Iq into a high-frequency q-axis current Iqh and a high-frequency removed q-axis current Iqm. Here, the high-frequency voltage is applied intermittently, and the application and non-application periods are repeatedly switched. Furthermore, the digital filters such as notch filters used to remove the high-frequency current in Examples 6 and 7 perform filtering using past input and output values. Therefore, if the high-frequency currents included in the d-axis current Id and q-axis current Iq, which are the input values ​​of the filter, change rapidly when the application and non-application periods are switched, the filter output becomes unstable. In addition, in Example 6, since filters are used for both the extraction of the high-frequency d-axis current Idh and high-frequency q-axis current Iqh, and the extraction of the high-frequency removed d-axis current Idm and high-frequency removed q-axis current Iqm, the processing time becomes longer. On the other hand, the method of Example 1 removes the continuously applied non-high frequency current by the drive component removal filter 61 to extract the high frequency d-axis current Idh and high frequency q-axis current Iqh. Then, the high frequency removed d-axis current Idm is calculated by subtracting the high frequency d-axis current Idh from the d-axis current Id using the high frequency current subtractor 41, and the high frequency removed q-axis current Iqm is calculated by subtracting the high frequency q-axis current Iqh from the q-axis current Iq. Therefore, the control of the motor M is most stable according to the method of Example 1.

[0127] As described above, the motor control device of this disclosure (motor control device 100a in the embodiment) includes an estimator (position estimator 32, PLL controller 31, and axis error calculator 30 in the embodiment) and an application unit (high-frequency voltage command value generator 43 in Embodiment 1). The estimator estimates the position of the rotor of the motor based on the high-frequency current generated when a high-frequency voltage is applied to the motor (motor M in the embodiment). The application unit intermittently applies the high-frequency voltage to the motor.

[0128] For example, the application unit provides a section at predetermined time intervals in which no high-frequency voltage is applied to the motor.

[0129] For example, the application unit provides sections at predetermined intervals of the high-frequency voltage where no high-frequency voltage is applied to the motor.

[0130] Furthermore, the estimator includes an axis error calculator (axis error calculator 30 in the embodiment) that calculates the axis error using a high-frequency current. The axis error calculator includes a first in-phase mirror phase current vector generator (in-phase mirror phase current vector generator 301 in the embodiment), a second in-phase mirror phase current vector generator (filter-corrected current estimators 303, 305 in the embodiment), and a mirror phase estimator (mirror phase estimator 302 in the embodiment). The first in-phase mirror phase current vector generator calculates the first in-phase mirror phase current vector using a high-frequency current. The second in-phase mirror phase current vector generator calculates the second in-phase mirror phase current vector by estimating the in-phase mirror phase current vector that occurs when a high-frequency voltage is applied to the motor. The mirror phase estimator calculates the axis error using the first in-phase mirror phase current vector or the second in-phase mirror phase current vector.

[0131] Furthermore, the mirror phase estimator calculates the axis error using the first in-phase mirror phase current vector in the first section, while calculating the axis error using the second in-phase mirror phase current vector in the second section. The first section is the section from the point after a predetermined waiting time has elapsed from the first start point (start of the applied section in the embodiment) when the high-frequency voltage is applied to the motor, to the end point (end of the applied section in the embodiment) when the high-frequency voltage is applied to the motor (the first predetermined section in Embodiment 1). The second section is the section from the end point when the high-frequency voltage is applied to the motor, to the point after a predetermined waiting time has elapsed from the second start point (start of the next applied section in the embodiment) when the high-frequency voltage is applied to the motor (the second predetermined section in Embodiment 1).

[0132] Furthermore, the motor control device of this disclosure includes a current calculator (3φ current calculator 28 in the embodiment) and a current component separator (drive component removal filter 61 and high-frequency current subtractor 41 in Embodiment 1). The current calculator calculates the current flowing through the motor windings. The current component separator includes a drive component removal filter (drive component removal filter 61 in Embodiment 1) and a subtractor (high-frequency current subtractor 41 in Embodiment 1), and separates the high-frequency current and the motor drive current from the current flowing through the motor windings. The drive component removal filter extracts the high-frequency current from the current flowing through the motor windings by removing the drive current from the current flowing through the motor windings. The subtractor extracts the drive current from the current flowing through the motor windings by subtracting the high-frequency current extracted by the drive component removal filter from the current flowing through the motor windings.

[0133] Furthermore, at the end of the section in which high-frequency voltage is applied to the motor, the application unit applies the q-axis high-frequency voltage for a period one-quarter longer than the d-axis high-frequency voltage. [Explanation of Symbols]

[0134] 100a, 100b, 100c Motor Control Device 28 3φ current calculator 30 Axis error calculator 301 Common-mode mirror-phase current vector generator 302 Mirror Phase Estimator 303,305 Filter Correction Current Estimator 31 PLL controller 32 Position estimator 41 High-frequency current subtractor 43. High-frequency voltage command value generator 61. Drive component removal filter M Motor

Claims

1. An estimator that estimates the position of the rotor of the motor based on the high-frequency current generated when a high-frequency voltage is applied to the motor, An application unit that intermittently applies the aforementioned high-frequency voltage to the motor, It is equipped with, The estimator comprises an axis error calculator that calculates the axis error using the high-frequency current, The aforementioned axis error calculator is A first in-phase mirror phase current vector generator that calculates a first in-phase mirror phase current vector using the aforementioned high-frequency current, A second in-mode mirror phase current vector generator calculates a second in-mode mirror phase current vector by estimating the in-mode mirror phase current vector generated when the aforementioned high-frequency voltage is applied to the motor, A mirror phase estimater that calculates the axis error using the first in-phase mirror phase current vector or the second in-phase mirror phase current vector, Having, Motor control device.

2. The application unit provides intervals at predetermined time points in which the high-frequency voltage is not applied to the motor. The motor control device according to claim 1.

3. The application unit provides intervals in which the high-frequency voltage is not applied to the motor at predetermined intervals of the high-frequency voltage. The motor control device according to claim 1.

4. The mirror phase estimator calculates the axis error using the first in-phase mirror phase current vector in the first section, while calculating the axis error using the second in-phase mirror phase current vector in the second section. The first section is the section from the time a predetermined waiting time has elapsed from the first start time when the application of the high-frequency voltage to the motor begins, to the end time when the application of the high-frequency voltage to the motor ends. The second section is the section from the end time to the second start time when the application of the high-frequency voltage to the motor begins, and up to the time when the predetermined waiting time has elapsed. The motor control device according to claim 1.

5. A current calculator for calculating the current flowing through the windings of the motor, A current component separator that separates the high-frequency current and the motor drive current from the aforementioned current, Furthermore, it is equipped with, The current component separator is, A drive component removal filter that extracts the high-frequency current from the current by removing the drive current from the current, A subtractor that extracts the drive current from the current by subtracting the high-frequency current extracted by the drive component removal filter from the current, Having, The motor control device according to claim 1.

6. The application unit applies the q-axis high-frequency voltage for a period of one-quarter of a cycle longer than the d-axis high-frequency voltage at the end of the section in which the high-frequency voltage is applied to the motor. The motor control device according to claim 3.

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