Motor control device

Abstract

To rightly detect a lock state of a motor.SOLUTION: In a motor control device 100 having a synchronous driving mode in which a motor M is synchronized with a rotation phase of a control system coordinate axis based on a speed command value and a position sensorless control mode in which the rotation phase of the control system coordinate axis is generated on the basis of a speed estimation value obtained by adjusting an axis error through feedback control, a synchronous driving current command value generator 13 adjusts a d-axis current command value id* and q-axis current command value iq* to bring an axis error Δθ close to 0, and a lock determiner 52 determines that the motor M is locked when a current amplitude value at q predetermined timing is equal to or more than a threshold in the synchronous driving mode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a motor control device.

Background Art

[0002] As one of the controls of a PMSM (Permanent Magnet Synchronous Motor), sensorless control for estimating the rotor position of the motor (hereinafter sometimes referred to as "position estimation") using the induced voltage generated as the motor rotates (hereinafter sometimes referred to as the "motor induced voltage") is known. In sensorless control, the error in position estimation becomes large in the stopped state of the motor or in the extremely low rotation state where the motor induced voltage is small.

[0003] On the other hand, as an operation mode different from the sensorless control mode, a "synchronous operation mode" is provided in which the motor is synchronized with the rotational phase of the control system coordinate axis based on the speed command value. After adjusting the phase of the current vector (hereinafter sometimes referred to as the "current phase") so that the shaft error is near 0 in the synchronous operation mode, there is a technique for shifting the operation mode from the synchronous operation mode to the sensorless control mode.

[0004] Also, a technique is known for detecting that the motor is in a state where it cannot rotate (hereinafter sometimes referred to as the "locked state") using the motor induced voltage.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when detecting the occurrence of the locked state using the motor induced voltage, there may be a situation where the locked state cannot be correctly detected due to variations in the constant of the motor induced voltage (hereinafter sometimes referred to as the "induced voltage constant") or the influence of the output error of the inverter.

[0007] Therefore, the present disclosure proposes a technique capable of correctly detecting the locked state of the motor.

Means for Solving the Problems

[0008] The motor control device of the present disclosure has a synchronous operation mode for synchronizing the motor with the rotational phase of the control system coordinate axis based on the speed command value, and a sensorless control mode in which the rotational phase of the control system coordinate axis is generated based on the speed estimated value obtained by feedback controlling the axis error. Further, the motor control device of the present disclosure has a synchronous operation current command value generator and a lock determination device. The synchronous operation current command value generator adjusts the current command value so as to bring the axis error closer to 0 in the synchronous operation mode. The lock determination device determines that the motor is locked when the current amplitude value at a predetermined timing is equal to or greater than the threshold value in the synchronous operation mode.

Effects of the Invention

[0009] According to the present disclosure, the locked state of the motor can be correctly detected.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0011] Hereinafter, examples of the present disclosure will be described with reference to the drawings. In the following examples, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0012] [Example] <Motor control device configuration> Fig. 1 is a diagram showing an example configuration of a motor control device according to an embodiment of the present disclosure. In Fig. 1, the motor control device 100 includes subtractors 11, 18, and 19, a speed controller 12, a current controller 20, adders 21 and 22, a dq / uvw converter 23, a PWM (Pulse Width Modulation) processor 24, and an IPM (Intelligent Power Module) 25. The IPM 25 is connected to a motor M. Examples of the motor M include PMSMs such as an IPMSM (Interior Permanent Magnet Synchronous Motor) and an SPMSM (Surface Permanent Magnet Synchronous Motor).

[0013] The motor control device 100 also has a current detector 28, a uvw / dq converter 29, an axis error calculator 30, a PLL (Phase Locked Loop) controller 31, a position estimator 32, and a decoupling controller 36.

[0014] The motor control device 100 also has a current command value generator 10, switches SW1, SW2, and SW3, an operation mode switch 40, a current amplitude calculator 51, and a lock determinator 52. The current command value generator 10 has a synchronous operation current command value generator 13 and a sensorless current command value generator 14. Each of the switches SW1, SW2, and SW3 has an A contact and a B contact.

[0015] The operation modes of the motor control device 100 include a synchronous operation mode and a position sensorless control mode. An operation mode switch 40 switches the operation mode of the motor control device 100 between the synchronous operation mode and the position sensorless control mode. The operation mode switch 40 is controlled by a controller external to the motor control device 100. When the operation mode is the synchronous operation mode, the operation mode switch 40 operates the synchronous operation current command value generator 13 in the current command value generator 10 while stopping the operation of the sensorless current command value generator 14, and connects the switches SW1, SW2, and SW3 to contact B. When the operation mode is the position sensorless control mode, the operation mode switch 40 operates the sensorless current command value generator 14 in the current command value generator 10 while stopping the operation of the synchronous operation current command value generator 13, and connects the switches SW1, SW2, and SW3 to contact A. The synchronous operation current command value generator 13 generates a current command value when the operation mode is the synchronous operation mode. The sensorless current command value generator 14 generates a current command value when the operation mode is the position sensorless control mode.

[0016] The axis error calculator 30 calculates an axis error Δθ, which is the difference between the dc-qc coordinate axes, which are the control system coordinate axes, and the dq coordinate axes, which are the rotor coordinate axes of the motor M, based on the d-axis current detection value id, the q-axis current detection value iq, the d-axis voltage command value Vd, and the q-axis voltage command value Vq. The axis error Δθ calculated by the axis error calculator 30 is input to the PLL controller 31 and the synchronous operation current command value generator 13.

[0017] The position estimator 32 generates the rotational phase θdq of the dc-qc coordinate axes by integrating the speed information input via the switch SW3. When the operation mode is the synchronous operation mode, the switch SW3 is connected to the contact B, and therefore the speed command value ω * is input as speed information to the position estimator 32. Therefore, in the synchronous operation mode, the speed command value ω *On the other hand, when the operation mode is in the position sensorless control mode, the switch SW3 is connected to the contact A, and therefore the speed estimation value ω, which is an estimate of the electrical angular velocity output from the PLL controller 31, is input to the position estimator 32 as speed information. Therefore, in the position sensorless control mode, the rotational phase θdq is generated based on the speed estimation value ω obtained by feedback control of the axis error Δθ.

[0018] The current controller 20 calculates the d-axis current command value id * The current controller 20 calculates the d-axis voltage command value Vd_cc before decoupling by proportional-plus-integral control of the d-axis current error id_dif, which is the error between the q-axis current command value iq * and the q-axis current detection value iq, and calculates the q-axis voltage command value Vq_cc before decoupling by proportional-plus-integral control of the q-axis current error iq_dif. For example, the current controller 20 calculates the d-axis voltage command value Vd_cc according to equation (1), and calculates the q-axis voltage command value Vq_cc according to equation (2). In equation (1), Kp_d is the d-axis proportional gain, and Ki_d is the d-axis integral gain, and in equation (2), Kp_q is the q-axis proportional gain, and Ki_q is the q-axis integral gain.

number

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[0019] The decoupling controller 36 controls the speed command value ω * and the d-axis current command value id * and the q-axis current command value iq * The decoupling controller 36 calculates a d-axis decoupling voltage command value Vd_a for compensating for the d-axis voltage command value Vd_cc based on the speed command value ω * and the d-axis current command value id * and the q-axis current command value iq *Based on this, a q-axis decoupled voltage command value Vq_a for compensating the q-axis voltage command value Vq_cc is calculated. For example, the decoupling controller 36 calculates the d-axis decoupled voltage command value Vd_a according to Equation (3) and calculates the q-axis decoupled voltage command value Vq_a according to Equation (4). In Equation (3) and Equation (4), R is the winding resistance of the motor M, Ld is the d-axis inductance of the motor M, Lq is the q-axis inductance of the motor M, and Ψa is the armature cross magnetic flux of the motor M.

Number

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[0020] Here, by using the currents used for calculating the d-axis decoupled voltage command value Vd_a and the q-axis decoupled voltage command value Vq_a in the decoupling controller 36 as the d-axis current command value id * and the q-axis current command value iq * it becomes possible to make the control of the motor M follow even a rapid change in the current command value. Therefore, in the current adjustment section in the synchronous operation mode described later, even in a situation where the d-axis current command value id * and the q-axis current command value iq * instantaneously change, it is possible to achieve both the stability and responsiveness of the control of the motor M.

[0021] The adder 21 calculates the final d-axis voltage command value Vd by adding the d-axis decoupled voltage command value Vd_a to the d-axis voltage command value Vd_cc according to Equation (5). Further, the adder 22 calculates the final q-axis voltage command value Vq by adding the q-axis decoupled voltage command value Vq_a to the q-axis voltage command value Vq_cc according to Equation (6). As a result, the d-axis voltage command value Vd and the q-axis voltage command value Vq in which the interference between the d-q coordinate axes is canceled by feedforward are calculated.

Number

Number

[0022] The dq / uvw converter 23 converts the two-phase d-axis voltage command value Vd and q-axis voltage command value Vq output from the adders 21 and 22 into a three-phase U-phase voltage command value Vu, a V-phase voltage command value Vv, and a W-phase voltage command value Vw, based on the rotational phase θdq output from the position estimator 32.

[0023] The PWM processor 24 generates six-phase PWM signals based on the U-phase voltage command value Vu, the V-phase voltage command value Vv, and the W-phase voltage command value Vw, and the PWM carrier signal, and outputs the generated six-phase PWM signals to the IPM 25.

[0024] The IPM 25 generates three-phase AC voltages, U phase, V phase, and W phase, from the DC voltage Vdc based on the six-phase PWM signal output from the PWM processor 24, and applies each of the generated three-phase AC voltages to the U phase, V phase, and W phase of the motor M.

[0025] When the bus current of the IPM 25 is detected using the one-shunt method, the current detector 28 detects the U-phase current value iu, the V-phase current value iv, and the W-phase current value iw of the motor M from the six-phase PWM signals output from the PWM processor 24 and the detected bus current, and outputs the phase current values iu, iv, and iw of each phase to the uvw / dq converter 29. Note that the current detector 28 may also detect the phase current values iu, iv, and iw of each phase using the two-transistor method.

[0026] The uvw / dq converter 29 converts the three-phase U-phase current value iu, V-phase current value iv, and W-phase current value iw into two-phase d-axis current detection value id and q-axis current detection value iq based on the rotational phase θdq output from the position estimator 32.

[0027] The PLL controller 31 performs proportional-plus-integral control of the position error Δθ to calculate a speed estimate ω that will make the position error Δθ 0. The speed estimate ω calculated by the PLL controller 31 is input to the position estimator 32 via the switch SW3, which corrects the rotational phase θdq, and as a result, the position error Δθ can approach 0.

[0028] The subtractor 11 calculates a speed error Δω by subtracting the speed estimated value ω from the speed command value ω * thereby calculating a speed error Δω.

[0029] The speed controller 12 generates a torque command value T for bringing the speed error Δω closer to 0 by performing proportional-integral control on the speed error Δω. * For example, the speed controller 12 generates the torque command value T * according to Equation (7). In Equation (7), Kp_sc is the proportional gain of the speed controller 12, and Ki_sc is the integral gain of the speed controller 12. Also, when the operation mode shifts from the synchronous operation mode to the sensorless control mode, the speed controller 12 calculates the torque command value T * based on the d-axis current command value id * and the q-axis current command value iq. *

Equation

[0030] When the operation mode is the sensorless control mode, the sensorless current command value generator 14 converts the torque command value T * into a current vector on the d-q coordinate axes based on a constant torque curve, which is the locus of the current when the torque command value T * is constant, thereby generating a sensorless d-axis current command value id_sl * and a sensorless q-axis current command value iq_sl. * Hereinafter, the sensorless d-axis current command value and the sensorless q-axis current command value may be collectively referred to as the "sensorless current command value".

[0031] Here, when the motor M is an SPMSM, the sensorless current command value generator 14 sets the sensorless d-axis current command value id_sl * on the constant torque curve to 0 and the sensorless q-axis current command value iq_sl * ​While generating, when the motor M is an IPMSM, the sensorless d-axis current command value id_sl is obtained from the intersection point of the constant torque curve and the MTPA curve (maximum torque / current control curve) (hereinafter sometimes referred to as the "intersection point of the two curves"). * and the sensorless q-axis current command value iq_sl * are preferably generated.

[0032] For example, when the motor M is an SPMSM, the sensorless current command value generator 14 substitutes 0 into the sensorless d-axis current command value id_sl * in the motor torque equation shown in Equation (8) to obtain the sensorless q-axis current command value iq_sl * shown in Equation (9). In Equations (8) and (9), Pn is the number of pole pairs of the motor M.

Equation

Equation

[0033] Also for example, when the motor M is an IPMSM, the sensorless current command value generator 14 calculates the sensorless d-axis current command value id_sl * and the sensorless q-axis current command value iq_sl * according to the motor torque equation shown in Equation (8) and Equation (10).

Equation

[0034] First, by eliminating the sensorless d-axis current command value id_sl * from Equations (8) and (10), Equation (11), which is a quartic equation regarding the sensorless q-axis current command value iq_sl * is obtained.

Equation

[0035] One of the real solutions of the quartic equation shown in equation (11) is the sensorless q-axis current command value iq_sl at the intersection of the two curves. * Therefore, the sensorless current command value generator 14 derives the solution of the equation (11) to obtain the sensorless q-axis current command value iq_sl * The solution of the quartic equation can be derived using, for example, Newton's method. The sensorless current command value generator 14 calculates the sensorless q-axis current command value iq_sl using equation (11). * After calculating the sensorless q-axis current command value iq_sl in equation (10), * By substituting the above, the sensorless d-axis current command value id_sl * Calculate.

[0036] When the operation mode is the position sensorless control mode, the switches SW1 and SW2 are connected to the contact A, and therefore the sensorless d-axis current command value id_sl generated by the sensorless current command value generator 14 is * and sensorless q-axis current command value iq_sl * is the d-axis current command value id input to the subtractors 18 and 19 and the decoupling controller 36. * and q-axis current command value iq * This becomes:

[0037] On the other hand, when the operation mode is the synchronous operation mode, the switches SW1 and SW2 are connected to the contact B, so that the synchronous operation d-axis current command value id_sy generated by the synchronous operation current command value generator 13 is * and synchronous operation q-axis current command value iq_sy * is the d-axis current command value id input to the subtractors 18 and 19 and the decoupling controller 36. * and q-axis current command value iq * When the operation mode is the synchronous operation mode, the synchronous operation d-axis current command value id_sy generated by the synchronous operation current command value generator 13 is * and synchronous operation q-axis current command value iq_sy * is input to the current amplitude calculator 51.

[0038] The subtractor 18 calculates the d-axis current command value id *The subtractor 19 calculates the d-axis current error id_dif by subtracting the d-axis current detection value id from the q-axis current command value iq * The q-axis current error iq_dif is calculated by subtracting the q-axis current detection value iq from

[0039] The current amplitude calculator 51 calculates the synchronous operation d-axis current command value id_sy * and synchronous operation q-axis current command value iq_sy * Based on this, the current amplitude value ia_amp is calculated according to equation (12).

number

[0040] The current amplitude calculator 51 calculates the synchronous operation d-axis current command value id_sy * and synchronous operation q-axis current command value iq_sy * Alternatively, the current amplitude value ia_amp may be calculated according to equation (13) based on a value id_LPF obtained by low-pass filtering the d-axis current detection value id and a value iq_LPF obtained by low-pass filtering the q-axis current detection value iq. By low-pass filtering the d-axis current detection value id and the q-axis current detection value iq, the current amplitude value ia_amp can be calculated based on values from which harmonic components such as noise have been removed, thereby improving the accuracy of determination by a lock determinator 52, which will be described later.

number

[0041] Lock determinator 52 determines whether motor M is in a locked state based on current amplitude value ia_amp. Furthermore, when lock determinator 52 determines that motor M is in a locked state, it outputs a signal (hereinafter sometimes referred to as a "lock state signal") LS indicating that motor M is in a locked state to the outside of motor control device 100 (for example, to a higher-level controller). Hereinafter, the determination of whether motor M is in a locked state may be referred to as a "lock state determination."

[0042] <Operation of the Motor Control Device When the Motor Is Not in the Locked State> FIGS. 2 and 3 are diagrams showing operation examples of the motor control device according to an embodiment of the present disclosure. FIGS. 2 and 3 show operation examples when the motor M is not in the locked state. Further, FIG. 2 shows an operation example under a light load, and FIG. 3 shows an operation example under an overload. When the motor M is starting up or rotating at a low speed, since the induced voltage of the motor M is small, an error occurs in the shaft error Δθ calculated by the shaft error calculator 30, and there is a risk that the control of the motor M may become unstable due to the influence of the error occurring in the shaft error Δθ. Therefore, in order to raise the rotational speed of the motor M to a rotational speed at which sensorless control can be applied, positioning and synchronous operation are performed before performing sensorless control. That is, as shown in FIGS. 2 and 3, the operation mode of the motor control device 100 shifts in the order of the positioning mode M1, the synchronous operation mode M2, and the sensorless control mode M3. When the operation mode is the positioning mode M1 or the synchronous operation mode M2, the operation mode switch 40 operates the synchronous operation current command value generator 13 in the current command value generator 10 while stopping the operation of the sensorless current command value generator 14, and connects the switches SW1, SW2, and SW3 to the contact point B. Along with the stop of the operation of the sensorless current command value generator 14, the operations of the speed controller 12 and the PLL controller 31 located on the input side of the sensorless current command value generator 14 are also stopped. When the operation mode is the sensorless control mode M3, the operation mode switch 40 operates the sensorless current command value generator 14 in the current command value generator 10 while stopping the operation of the synchronous operation current command value generator 13, and connects the switches SW1, SW2, and SW3 to the contact point A.

[0043]

[0044] ​When the operation mode is the positioning mode M1 or the synchronous operation mode M2, the switches SW1 and SW2 are connected to the contact B, so that the synchronous operation d-axis current command value id_sy generated by the synchronous operation current command value generator 13 is * and synchronous operation q-axis current command value iq_sy * is the d-axis current command value id input to the subtractors 18 and 19 and the decoupling controller 36. * and q-axis current command value iq * On the other hand, when the operation mode is the position sensorless control mode M3, the switches SW1 and SW2 are connected to the contacts A, and therefore the sensorless d-axis current command value id_sl generated by the sensorless current command value generator 14 is * and sensorless q-axis current command value iq_sl * is the d-axis current command value id input to the subtractors 18 and 19 and the decoupling controller 36. * and q-axis current command value iq * This becomes:

[0045] As shown in FIGS. 2 and 3, in the positioning mode M1, the speed command value ω * is set to 0, and the synchronous operation current command value generator 13 generates the d-axis current command value id * is increased from 0 to a predetermined value id_ini, while the q-axis current command value iq * Set to 0. d-axis current command value id * While the current is increasing, the rotor of the motor M starts to move and is positioned. For example, by setting the current value capable of driving the maximum load as the predetermined value id_ini, the motor M can be started without losing synchronism even when overloaded in the synchronous operation mode M2. The predetermined value id_ini also serves as a guide for setting the current threshold value i_jd (hereinafter sometimes referred to as the "lock determination threshold") used when determining whether the motor is in a locked state.

[0046] 2 and 3, in the speed increase section I1, the synchronous operation current command value generator 13 sets the d-axis current command value id_ini as the initial value. * is kept constant at a predetermined value id_ini, and the q-axis current command value iq * While keeping constant at 0, the speed command value ω* is linearly increased from 0 to the predetermined rotation speed ω1. As a result, in the speed increase section I1, the d-axis current command value id * and q-axis current command value iq * While the rotation speed of the motor M is kept constant, the rotation speed of the motor M increases to a predetermined rotation speed corresponding to the predetermined rotation speed ω1. The predetermined rotation speed ω1 is preset to a rotation speed at which it is known that the motor induced voltage can be sufficiently detected, for example, 15 rps.

[0047] Next, in the current adjustment section I2, the speed command value ω * is kept constant at a predetermined rotation speed ω1, the synchronous operation current command value generator 13 generates the d-axis current command value id * and q-axis current command value iq * In the current adjustment section I2, the synchronous operation current command value generator 13 adjusts the d-axis current command value id using the predetermined value id_ini as the initial value. * The d-axis current command value id in the current adjustment section I2 is adjusted. * and q-axis current command value iq * In the current adjustment section I2, the synchronous operation current command value generator 13 adjusts the current vector on the dc-qc coordinate axes to a state close to the current vector in the position sensorless control mode M3 by adjusting the d-axis current command value id * is converged to the target command value id_sy_end at the end point of the current regulation section I2 by using a filter or by linearly decreasing it. The target command value id_sy_end has a positive value close to 0 and is slightly over-excited (id * It is preferable to set it to a value such that

[0048] That is, in the speed increase section I1, the synchronous operation current command value generator 13 sets the d-axis current command value id_ini to a predetermined value id_ini that is greater than the target command value id_sy_end. * In the current adjustment section I2 following the speed increase section I1, the synchronous operation current command value generator 13 sets the d-axis current command value id *is gradually decreased to the target command value id_sy_end.

[0049] Generally, when the motor M is an SPMSM that does not have saliency, the d-axis current command value id on the constant torque curve is * is set to 0, and if the motor M is an IPMSM with salient poles, the position sensorless control is performed based on the intersection of the two curves. On the other hand, in the synchronous operation mode M2, the rotation phase θdq is not corrected based on the speed estimate value ω calculated by the PLL controller 31, so the d-axis current command value id is set to 0 until the d-axis current at which the current amplitude value required to obtain the desired torque is minimized. * If the d-axis current command value id is decreased, depending on the response speed of the synchronous operation current command value generator 13 when generating the current command value, the load torque may exceed the output torque, and the motor M may lose synchronization. For this reason, as described above, the d-axis current command value id at the end point of the current adjustment section I2 is decreased. * It is preferable to converge to a slight overexcitation.

[0050] In addition, by setting the target command value id_sy_end at the end of the current adjustment section I2 to a value approximately 10% of the rated current amplitude value of the motor M or the current amplitude value when the motor M drives the maximum load, the d-axis current command value id * The d-axis current command value id in position sensorless control mode M3 * Since the target command value id_sy_end can be converged to a slight over-excitation while being reasonably close to , it is possible to prevent the motor M from losing synchronization in the current adjustment section I2. For example, when the rated current amplitude value is about 10 A, it is preferable to set the target command value id_sy_end to about 1 A.

[0051] In the current adjustment section I2, the synchronous operation current command value generator 13 controls the axis error Δθ by integral or proportional integral control, thereby obtaining the q-axis current command value iq * When the axis error Δθ is positive, the synchronous operation current command value generator 13 generates the q-axis current command value iq * When the axis error Δθ is negative, the q-axis current command value iq *In this way, in the current adjustment section I2, the synchronous operation current command value generator 13 reduces the q-axis current command value iq by feedback control so as to bring the axis error Δθ closer to zero. * In the current regulation section I2, the synchronous operation current command value generator 13 adjusts the q-axis current command value iq according to, for example, equation (14). * In equation (14), Ki_iq is the integral gain.

number

[0052] In the position sensorless control mode M3, when the axis error Δθ is positive, the PLL controller 31 reduces the speed estimate ω so that the speed estimate ω becomes equal to the speed command value ω. * Since the torque command value T * is increased, and the sensorless current command value generator 14 generates the q-axis current command value iq * On the other hand, in the synchronous operation mode M2, the speed command value ω * is directly input to the position estimator 32, the synchronous operation current command value generator 13 directly calculates the q-axis current command value iq * Therefore, the d-axis current command value id at the start point of the current adjustment section I2 is adjusted. * The desired response speed of the synchronous operation current command value generator 13 can be obtained by adjusting the integral gain Ki_iq (equation (14)) according to the magnitude of the predetermined value id_ini, which is the initial value of the motor M, the inertia of the motor M, the induced voltage constant of the motor M, or the characteristics of the load driven by the motor M.

[0053] When transitioning from the current adjustment section I2 to the position sensorless control mode M3, the speed controller 12 calculates the d-axis current command value id * and q-axis current command value iq * (That is, the d-axis current command value id in synchronous operation mode M2 * and the q-axis current command value iq in synchronous operation mode M2. * The torque command value T* is calculated, and the torque command value T calculated according to Equation (15) * is set as the initial value of the proportional-integral control with respect to the speed error Δω (that is, the torque command value T generated by the speed controller 12 * of the initial value). By doing so, the occurrence of discontinuity of the torque command value T when the operation mode switches from the synchronous operation mode M2 to the sensorless control mode M3 can be prevented, and thus the switching shock generated in the motor M due to the switching of the operation mode can be reduced. *

Equation

[0054] Also, since the torque command value T calculated according to Equation (15) * is the initial value of the proportional-integral control with respect to the speed error Δω when the sensorless control is started, in the sensorless control mode M3, the sensorless d-axis current command value id_sl generated by the sensorless current command value generator 14 * is adjusted to a value smaller than the target command value id_sy_end, as shown in FIGS. 2 and 3. For example, when the target command value id_sy_end has a positive value near 0, the sensorless d-axis current command value id_sl * is adjusted to a value of 0 or less.

[0055] As described above, by converging the d-axis current command value near 0 at the stage of synchronous operation and generating the q-axis current command value by feedback controlling the axis error, it is possible to shift from synchronous operation to sensorless control in a state where the axis error is adjusted near 0 and the degree of overexcitation is suppressed. Therefore, since the change in the current vector after the transition to sensorless control becomes small, even in an IPMSM having saliency, it is possible to reduce the switching shock due to current jumps, speed jumps, etc. during the transition to sensorless control. Thus, regardless of the type of the motor M, whether it has saliency or not, the stability of the control of the motor M during the transition to the sensorless control mode can be improved. Thus, regardless of the type of the motor M, stable starting of the motor M becomes possible. ​

[0056] <Configuration of synchronous operation current command value generator> 4 is a diagram illustrating an example of the configuration of a synchronous operation current command value generator according to an embodiment of the present disclosure. In FIG. 4, the synchronous operation current command value generator 13 includes a d-axis current command value generator 131, a q-axis current command value generator 132, and a q-axis current command value limiter 133.

[0057] When the operation mode is the positioning mode M1 or the synchronous operation mode M2, the d-axis current command value generator 131 generates the synchronous operation d-axis current command value id_sy as described above with reference to FIGS. 2 and 3. * (d-axis current command value id * )

[0058] When the operation mode is the positioning mode M1 or the synchronous operation mode M2, the q-axis current command value generator 132 integrates the axis error Δθ as described above with reference to FIGS. 2 and 3 to obtain the synchronous operation q-axis current command value iq_sy before limitation. * '(q-axis current command value iq * )

[0059] The q-axis current command value limiter 133 is a function of a predetermined current amplitude limit value ia_lim and a synchronous operation d-axis current command value id_sy. * Based on this, the q-axis current limit value iq_lim is calculated according to equation (16).

number

[0060] In addition, the q-axis current command value limiter 133 limits the synchronous operation q-axis current command value iq_sy * When ' is equal to or less than the q-axis current limit value iq_lim, the synchronous operation q-axis current command value iq_sy before limiting * ' is used as is to synchronize the q-axis current command value iq_sy * On the other hand, the synchronous operation q-axis current command value iq_sy before limiting is output as *When ’ is greater than the q-axis current limit value iq_lim, the q-axis current command value limiter 133 sets the q-axis current limit value iq_lim as the synchronous operation q-axis current command value iq_sy * and outputs it. That is, the q-axis current limit value iq_lim corresponds to the upper limit value for the synchronous operation q-axis current command value iq_sy * , and the upper limit of the synchronous operation q-axis current command value iq_sy * is restricted to the q-axis current limit value iq_lim. By restricting the upper limit of the synchronous operation q-axis current command value iq_sy * to the q-axis current limit value iq_lim calculated according to Equation (16), the synchronous operation q-axis current command value iq_sy with the upper limit of the current amplitude value restricted to the current amplitude limit value ia_lim is output from the synchronous operation current command value generator 13 * .

[0061] Here, it is preferable that the current amplitude value for driving the motor M at maximum load when not in the locked state is used as the current amplitude limit value ia_lim. That is, the q-axis current command value limiter 133 preferably uses the current amplitude value when the d-axis current command value id * is at the above-mentioned predetermined value id_ini as the current amplitude limit value ia_lim.

[0062] Also, when the upper limit of the synchronous operation q-axis current command value iq_sy * is restricted as described above, the phenomenon of windup can be suppressed by also restricting the upper limit of the output value of the integrator included in the q-axis current command value generator 132.

[0063] <Operation of Lock Determination Device> The lock determination device 52 receives the current amplitude value ia_amp from the current amplitude calculator 51.

[0064] The lock determination device 52 determines whether the motor M is in the locked state by comparing the current amplitude value ia_amp with the lock determination threshold value i_jd.

[0065] Here, the lockup determination threshold i_jd is a value smaller than the current amplitude limit value ia_lim. Furthermore, for example, by setting the lockup determination threshold i_jd to a value that is approximately 5% smaller than the above-mentioned predetermined value id_ini, the accuracy of the lockup determination can be improved. For example, if the current amplitude value in the current adjustment section I2 increases due to an overload even though the motor M is not in a lockedup state, it can be prevented from being erroneously determined that the motor M is in a lockedup state.

[0066] The lockup determinator 52 determines that the motor M is in a locked state when the current amplitude value ia_amp is not less than the lockup determination threshold i_jd at a predetermined timing TI after a predetermined time PT has elapsed since the control period transitioned to the current adjustment period I2. That is, the lockup determinator 52 determines that the motor M is locked up when the current amplitude value ia_amp at the predetermined timing TI is equal to or greater than the lockup determination threshold i_jd. On the other hand, the lockup determinator 52 determines that the motor M is not locked up when the current amplitude value ia_amp decreases to less than the lockup determination threshold i_jd at a predetermined timing TI after a predetermined time PT has elapsed since the control period transitioned to the current adjustment period I2. That is, the lockup determinator 52 determines that the motor M is not locked up when the current amplitude value ia_amp at the predetermined timing TI is less than the lockup determination threshold i_jd. The lockup determinator 52 outputs a locked up state signal LS when it determines that the motor M is in a locked up state, but does not output the locked up state signal LS when it determines that the motor M is not locked up.

[0067] For example, when the external controller of the motor control device 100 receives the lock state signal LS from the lock detector 52, it stops energizing the motor M in the current adjustment section I2 without shifting the operation mode from the synchronous operation mode M2 to the sensorless control mode M3. Here, when the motor M is in the locked state, no motor induced voltage is generated due to the rotation of the motor M. Therefore, if the operation mode shifts to the sensorless control mode M3 when the motor M is in the locked state, the sensorless control by the shaft error calculator 30, the PLL controller 31, and the speed controller 12 becomes unstable. Thus, as described above, when the motor M is in the locked state, by stopping the energization of the motor M before the operation mode shifts to the sensorless control mode M3, it is possible to prevent the shaft error calculator 30, the PLL controller 31, and the speed controller 12 used in the sensorless control from becoming unstable.

[0068] Here, the above-mentioned predetermined time PT is set to, for example, the same time as the length of the current adjustment section I2. Further, when there is concern about a failure of the motor M due to winding heating because the winding resistance of the motor M is large, it is preferable that the above-mentioned predetermined time PT is set to a time shorter than the length of the current adjustment section I2.

[0069] As described above, by performing the lock state determination using the current amplitude value ia_amp without using the motor induced voltage, the lock state determination is not affected by variations in the induced voltage constant or the output error of the inverter, so that the locked state of the motor M can be correctly detected.

[0070] <Operation of the motor control device when the motor is in the locked state> FIG. 5 is a diagram showing an operation example of the motor control device according to an embodiment of the present disclosure. FIG. 5 shows an operation example when the motor M is in the locked state.

[0071] As described above, the lock state determination is performed in the current adjustment section I2.

[0072] When the motor M is in a locked state, the motor will not rotate even if the current flowing through the motor M is increased, and the operation of the motor control device 100 is equivalent to the operation when the motor M is driven under significantly overload conditions. Therefore, when the q-axis current command value generator 132 integrates the axial error Δθ, the q-axis current command value iq * will diverge. As a result, the current amplitude value ia_amp will also show an increasing behavior, leading to a protective shutdown of the motor M to suppress demagnetization of the motor M (hereinafter sometimes referred to as a "current trip shutdown"). Furthermore, if the inertia of the load on the motor M is large, a large acceleration torque may be required even if the motor M is not in a locked state. Therefore, from the viewpoint of continuing to apply acceleration torque, it is not desirable for the motor M to immediately come to a protective shutdown.

[0073] Therefore, as described above, the d-axis current command value id * is the above-mentioned predetermined value id_ini is used as the current amplitude limit value ia_lim, so that the q-axis current command value iq * is limited. This allows the motor M to continue applying a torque equivalent to the above-mentioned predetermined value id_ini without coming to a current trip stop. In other words, it is possible to continue applying a torque sufficient to drive the maximum load when the motor is not in a locked state. Therefore, even if a torque equivalent to the maximum load when the motor is not in a locked state continues to be applied, if the current amplitude value ia_amp shows an increasing behavior, it is possible to determine that the load on the motor M is greater than the maximum load, and therefore it is possible to determine that the motor M is in a locked state.

[0074] The above is a description of the embodiment.

[0075] As described above, the motor control device of the present disclosure (the motor control device 100 of the embodiment) has a synchronous operation mode and a sensorless control mode. In the synchronous operation mode, the motor (the motor M of the embodiment) synchronizes with the rotation phase of the control system coordinate axis based on the speed command value. In the sensorless control mode, the rotation phase of the control system coordinate axis is generated based on the speed estimated value obtained by feedback controlling the axis error. Further, the motor control device of the present disclosure has a synchronous operation current command value generator (the synchronous operation current command value generator 13 of the embodiment) and a lock determination device (the lock determination device 52 of the embodiment). The synchronous operation current command value generator adjusts the current command value (the d-axis current command value id * , q-axis current command value iq * ) so as to bring the axis error close to 0 in the synchronous operation mode. The lock determination device determines that the motor is locked when the current amplitude value (the current amplitude value ia_amp of the embodiment) at a predetermined timing (the predetermined timing TI of the embodiment) is equal to or greater than the threshold value (the lock determination threshold value i_jd of the embodiment) in the synchronous operation mode.

[0076] Further, the threshold value for the current amplitude value is a value smaller than the first upper limit value (the current amplitude limit value ia_lim of the embodiment), which is the upper limit value of the current amplitude value.

[0077] The synchronous operation mode has a speed increase section and a current adjustment section, and the predetermined timing is in the current adjustment section.

[0078] Further, the synchronous operation current command value generator sets the d-axis current command value to a predetermined value (the predetermined value id_ini of the embodiment) in the speed increase section to increase the rotation speed of the motor to a predetermined rotation speed (the predetermined rotation speed ω1 of the embodiment), and then, in the current adjustment section, decreases the d-axis current command value to a target command value (the target command value id_sy_end of the embodiment) having a value smaller than the predetermined value, and adjusts the q-axis current command value by feedback control so as to bring the axis error close to 0.

[0079] Also, the synchronous operation current command value generator limits the q-axis current command value by a second upper limit value (q-axis current limit value iq_lim in the embodiment) which is the upper limit value of the q-axis current command value and is calculated based on the first upper limit value.

[0080] Also, the synchronous operation current command value generator uses, as the first upper limit value, the current amplitude value when the d-axis current command value is at a predetermined value (predetermined value id_ini in the embodiment).

Explanation of Signs

[0081] 100 Motor control device 12 Speed controller 13 Synchronous operation current command value generator 14 Sensorless current command value generator 32 Position estimator 51 Current amplitude calculator 52 Lock detector 131 d-axis current command value generator 132 q-axis current command value generator 133 q-axis current command value limiter

Claims

1. A motor control device having a synchronous operation mode for synchronizing a motor with the rotational phase of a control system coordinate axis based on a speed command value, and a sensorless control mode in which the rotational phase of the control system coordinate axis is generated based on a speed estimated value obtained by feedback control of an axis error, In the synchronous operation mode, a synchronous operation current command value generator that adjusts a current command value so as to bring the axis error closer to 0, In the synchronous operation mode, a lock determination device that determines that the motor is locked when a current amplitude value at a predetermined timing is equal to or greater than a threshold value, Comprising, The synchronous operation mode has an acceleration section and a current adjustment section, The synchronous operation current command value generator, In the acceleration section, after increasing the rotational speed of the motor to a predetermined rotational speed while keeping the d-axis current command value and the q-axis current command value constant, In the current adjustment section, the q-axis current command value is adjusted by feedback control so as to bring the axis error closer to 0, The predetermined timing is in the current adjustment section, Motor control device.

2. The threshold value is a value smaller than a first upper limit value that is the upper limit value of the current amplitude value, The motor control device according to claim 1.

3. The synchronous operation current command value generator limits the q-axis current command value by a second upper limit value that is the upper limit value of the q-axis current command value, The second upper limit value is calculated based on a first upper limit value that is the upper limit value of the current amplitude value, The motor control device according to claim 1.

4. The synchronous operation current command value generator uses, as the first upper limit value that is the upper limit value of the current amplitude value, the current amplitude value when the d-axis current command value is at the constant predetermined value, The motor control device according to claim 1.

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