JP2013066342A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a motor controller which allows for enhancement of acceleration performance and control performance by correcting the follow-up delay of magnetic flux for a magnetic flux command over a wide operation region including acceleration/deceleration and load torque variation, thereby ensuring output of a predetermined torque.SOLUTION: The motor controller comprises a flux controller 13 generating an excitation current command for reducing the deviation of an estimation magnetic flux ΦS estimated in a magnetic flux estimation unit 8 from a magnetic flux command Φcom input externally, and performs drive control of an induction motor 1 by vector control. The motor controller is further provided with a flux lag compensator 16a generating a flux lag correction command Φhcom on the basis of the magnetic flux command Φcom. The flux lag correction command Φhcom is used in a subtractor 20 for taking a deviation from the estimation magnetic flux ΦS estimated by the magnetic flux estimation unit 8 in place of the magnetic flux command Φcom.

Description

  The present invention relates to a motor control device that drives an induction motor by vector control, and more particularly to a motor control device that drives an induction motor used in a spindle of a machine tool, a vehicle, or the like.

  The induction motor generates a rotating magnetic field by passing a primary current through the stator. When the rotor crosses the magnetic flux generated by the rotating magnetic field, a voltage is induced in the rotor and a secondary current flows. The secondary current and the magnetic flux Torque is generated by the interaction with. In general, in drive control of an induction motor used in a spindle of a machine tool, a vehicle, or the like, a primary current flowing through a stator is divided into an excitation current for controlling a magnetic flux and a secondary current (that is, a torque current). , Vector control is used to control each of them individually. The torque generated in the rotor is proportional to the product of the magnetic flux generated by the excitation current and the torque current.

  In general, in the vector control of the induction motor, the torque of the induction motor is controlled by changing the magnetic flux while keeping the torque current constant. More specifically, a constant torque drive region is used up to the electric constant of the induction motor, such as winding resistance and inductance, and the rotation speed (base rotation speed) until reaching the upper limit voltage determined by the power supply voltage as the power source. Driving with constant torque and constant torque is performed (constant torque drive control). On the other hand, when the rotational speed reaching the upper limit voltage is reached, the magnetic flux is reduced in inverse proportion to the rotational speed to be increased. As a result, torque is also reduced and constant output driving is performed (constant output drive control).

  As described above, in an induction motor controlled by general vector control, constant torque drive control and constant output drive control are used in combination. For this reason, an induction motor is required to quickly follow an actual magnetic flux to a magnetic flux command value when the motor is started or when switching from constant torque drive control to constant output drive control. On the other hand, the magnetic flux is controlled by increasing / decreasing the excitation current, but the generated magnetic flux rises with respect to the excitation current with a time constant determined from the electrical constant of the motor. As a result, in actual control, tracking of the magnetic flux is delayed with respect to the magnetic flux command. When the follow-up delay of the magnetic flux occurs, the arrival time to the predetermined torque is also delayed, and there are problems that the acceleration time of the motor becomes long and the control performance cannot be improved.

  For example, Patent Document 1 discloses a technique for correcting the delay of the estimated magnetic flux with respect to the magnetic flux command by multiplying the deviation between the magnetic flux command and the estimated magnetic flux by a coefficient and multiplying the excitation current command corresponding to the magnetic flux command. Is disclosed.

  Further, Non-Patent Document 1 discloses an excitation current control system (a control that includes an excitation current controller in the interior so that the deviation between the excitation current command and the excitation current is small and follows the excitation current with respect to the excitation current command). System) as a minor loop, and a magnetic flux control system (a control system that has a magnetic flux controller inside to make the deviation between the magnetic flux command and the estimated magnetic flux small so that the estimated magnetic flux follows the magnetic flux command) is a major loop. A technology is disclosed in which the cascade control is configured so as to quickly follow the magnetic flux with respect to the magnetic flux command.

JP 2008-306798 A

"Theory and design of AC servo system" (general electronic publisher 5th edition, pages 111-112, Fig. 5.14)

  However, the technique described in Patent Document 1 is effective in shortening the rise time of magnetic flux with respect to a stepwise change in magnetic flux command such as switching from a non-excitation state to an excitation state. No consideration is given to the change in the magnetic flux command when driving with, and there is a problem that the magnetic flux cannot be tracked or the tracking of the magnetic flux is delayed with respect to the magnetic flux command in the constant output drive region.

  Further, as described above, the technique described in Non-Patent Document 1 constitutes a magnetic flux control system that causes the estimated magnetic flux to follow the magnetic flux command so that the deviation between the magnetic flux command and the estimated magnetic flux becomes small. For this reason, the speed at which the magnetic flux follows the magnetic flux command depends on the response of the magnetic flux control system (hereinafter referred to as “response band”). However, the excitation current control system disposed in the minor loop of the magnetic flux control system includes the current detection delay of the current detection unit, the conversion delay in the dq-UVW coordinate conversion and the UV-dq coordinate conversion, the conversion error, and the induction motor. It may be difficult to widen the response band due to various factors such as variations in electrical constants such as winding resistance and inductance, and errors. In such a case, if the response band of the magnetic flux control system is widened, the control stability is impaired, so it is difficult to widen the response band of the magnetic flux control system. When the response band of the magnetic flux control system cannot be expanded as described above, the follow-up of the magnetic flux is delayed with respect to the magnetic flux command.

  Even if the influence of each factor of the excitation current control system as described above is small and the response band of the magnetic flux control system can be expanded, the inverter circuit that supplies power to the induction motor is limited by the maximum allowable current. Therefore, it is necessary to limit the excitation current for increasing or decreasing the magnetic flux in order to match the restriction on the maximum allowable current value. In that case, if the response band of the magnetic flux control system is widened, there is a problem that the estimated magnetic flux overshoots the magnetic flux command and the time to reach the magnetic flux command is delayed. For this reason, the magnetic flux control system sets a response band in which the estimated magnetic flux does not overshoot the magnetic flux command, so that the follow-up of the magnetic flux is delayed with respect to the magnetic flux command as described above.

  The present invention has been made in view of the above, and can correct a tracking delay of a magnetic flux with respect to a magnetic flux command and output a predetermined torque in a wide operation region including acceleration / deceleration of an induction motor and load torque fluctuation. The object is to obtain a possible motor control device.

  In order to solve the above-described problems and achieve the object, the present invention includes a current detection unit that detects a primary current flowing in an induction motor, and a coordinate conversion that converts a torque current component and an excitation current component from the primary current. And a magnetic flux estimation means for estimating the magnetic flux of the induction motor from the excitation current component, and a deviation between the magnetic flux command input from the outside in the process of driving the induction motor and the magnetic flux estimated by the magnetic flux estimation means is small. Magnetic flux control means for generating an excitation current command to be, excitation current restriction means for outputting an excitation current command within a limit value among excitation current commands output by the magnetic flux control means as an excitation current command necessary for control, A magnetic flux lag for generating a magnetic flux lag correction command based on the magnetic flux command in a motor control device that drives and controls the three-phase induction motor by vector control Comprising a amortization means, said magnetic flux delay correction instruction, characterized in that it is used for taking a difference between the flux flux estimation means has estimated instead of the magnetic flux command.

  According to the present invention, in a wide operation region from the constant torque drive region to the constant output drive region of the induction motor, the estimated magnetic flux is estimated with respect to the magnetic flux command by the magnetic flux delay compensation command generated by the magnetic flux delay compensation means based on the magnetic flux command. The delay can be corrected. As a result, the predetermined torque can be quickly output in the constant torque drive region, and the rotational speed can be quickly increased in the constant output drive region.

FIG. 1 is a block diagram showing a main configuration of a motor control device according to Embodiment 1 of the present invention. FIG. 2 is a diagram for explaining the behavior of the magnetic flux control system including the magnetic flux controller and the excitation current limiter shown in FIG. FIG. 3 is a block diagram showing a configuration example of the magnetic flux lag compensator shown in FIG. FIG. 4 is a diagram illustrating characteristics of a motor to be controlled. FIG. 5 is a diagram for explaining the control characteristics of the motor with and without the magnetic flux lag compensator shown in FIG. FIG. 6 is a block diagram showing a main configuration of the motor control apparatus according to Embodiment 2 of the present invention. FIG. 7 is a block diagram showing a configuration example of the magnetic flux lag compensator shown in FIG. FIG. 8 is a diagram for explaining the control characteristics of the motor with and without the magnetic flux lag compensator shown in FIG. FIG. 9 is a block diagram showing another configuration example of the magnetic flux lag compensator shown in FIG. 6 as Embodiment 3 of the present invention. FIG. 10 is a block diagram illustrating a configuration example of the feedforward compensator illustrated in FIG. FIG. 11 is a diagram for explaining and comparing the control characteristics of the motor when the magnetic flux lag compensator shown in FIG. 9 is provided and when the magnetic flux lag compensator shown in FIG. 7 is provided.

  Embodiments of a motor control device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a main configuration of a motor control device according to Embodiment 1 of the present invention. In FIG. 1, an induction motor (hereinafter, simply referred to as “motor”) 1 to be controlled is a motor used in a spindle of a machine tool, a vehicle, or the like. A speed detector 2 is attached to the motor 1. The inverter circuit 3 includes a plurality of switching elements. The capacitor 4 stores DC power that is a power source of the motor 1. A current detection unit 5 is disposed on a power cable connecting the inverter circuit 3 and the motor 1.

  When an ON / OFF signal of a switching element is input from the base signal generator 12, the inverter circuit 3 uses a DC power stored in the capacitor 4 by a switching operation of the plurality of switching elements to generate an arbitrary frequency and voltage. Is supplied to the motor 1. At that time, a primary current flows through the motor 1, and the motor 1 is driven to rotate.

  The rotational speed ωmFB of the motor 1 at this time is detected by the speed detector 2, and the primary current flowing through the motor 1 at this time (in FIG. 1, for example, the primary currents Iu and Iv of UV two-phase are Is detected by the current detector 5.

  The rotational speed ωmFB detected by the speed detector 2 is input to the minus input terminal (−) of the subtractor 21 and one addition input terminal (+) of the adder 19. A rotational speed command ωmcom is input from the outside to the plus input terminal (+) of the subtractor 21. The output (speed deviation) of the subtracter 21 is input to the speed controller 14. The speed controller 14 generates a torque current command for reducing the speed deviation output from the subtractor 21 and outputs the torque current command to the torque current limiter 22. The torque current limiter 22 has two limit values consisting of an output upper limit and an output lower limit. When the torque current command generated by the speed controller 14 increases, the torque current limiter 22 is equal to or less than the output upper limit (set maximum value). When the torque current command generated by the speed controller 14 decreases, a torque current command equal to or higher than the output lower limit value (set minimum value) is output as a torque current command iqcom necessary for control. The torque current command iqcom is input to the plus input terminal (+) of the subtractor 18.

  The primary currents Iu and Iv detected by the current detection unit 5 are input to the coordinate converter 6. The coordinate converter 6 performs UV-dq coordinate conversion based on the rotational position estimated value θ1 that is the output of the integrator 15, and converts the excitation current idFB and torque current iqFB from the input primary currents Iu and Iv. To do.

  The excitation current idFB converted by the coordinate converter 6 is input to the magnetic flux estimator 8 and the minus input terminal (−) of the subtractor 17, respectively. The output (excitation current command idcom) of the excitation current limiter 23 is input to the plus input terminal (+) of the subtracter 17. The output (excitation current deviation) of the subtracter 17 is input to the excitation current controller 10. The excitation current controller 10 generates an excitation voltage command Vdcom that reduces the excitation current deviation output from the subtractor 17 and outputs the excitation voltage command Vdcom to the coordinate converter 7.

  The magnetic flux estimation unit 8 estimates the magnetic flux Φ from the excitation current idFB converted by the coordinate converter 6. The magnetic flux Φ (magnetic flux estimation ΦS) estimated by the magnetic flux estimator 8 becomes one input of the slip velocity calculator 9 and is input to the negative input terminal (−) of the subtractor 20.

  The magnetic flux delay compensation command Φhcom generated by the magnetic flux lag compensator 16 a from the externally input magnetic flux command Φcom is input to the plus input terminal (+) of the subtracter 20. The output (magnetic flux deviation) of the subtracter 20 is input to the magnetic flux controller 13. The magnetic flux controller 13 generates an excitation current command for reducing the magnetic flux deviation output from the subtracter 20 and outputs it to the excitation current limiter 23. The excitation current limiter 23 has two limit values consisting of an output upper limit and an output lower limit. When the excitation current command generated by the magnetic flux controller 13 increases, the excitation current limiter 23 is equal to or less than the output upper limit (set maximum value). When the excitation current command generated by the magnetic flux controller 13 decreases, the excitation current command equal to or higher than the output lower limit value (set minimum value) is output as the excitation current command idcom necessary for control. The excitation current command idcom is input to the plus input terminal (+) of the subtractor 17 as described above.

  The torque current iqFB converted by the coordinate converter 6 is input to the other input terminal of the slip speed calculation unit 9 and the negative input terminal (−) of the subtractor 18, respectively. The output (sliding speed ωS) of the sliding speed calculation unit 9 is input to the other addition input terminal of the adder 19.

  The output ω1 (ω1 = ωmFB + ωS) of the adder 19 is integrated by the integrator 15 to become a rotational position estimated value θ1, and is input to the coordinate converters 6 and 7 as a control signal. As described above, the coordinate converter 6 performs UV-dq coordinate conversion based on the rotational position estimation value θ1 that is the output of the integrator 15. In addition, as will be described later, the coordinate converter 7 performs dq-UVW coordinate conversion based on the rotational position estimated value θ1 that is the output of the integrator 15.

  The output (torque current command iqcom) of the torque current limiter 22 is input to the plus input terminal (+) of the subtractor 18. The output (torque current deviation) of the subtracter 18 is input to the torque current controller 11. The torque current controller 11 generates a torque voltage command Vqcom that reduces the torque current deviation output from the subtractor 18 and outputs the torque voltage command Vqcom to the coordinate converter 7.

  The coordinate converter 7 performs dq-UVW coordinate conversion based on the rotational position estimated value θ1 that is the output of the integrator 15, and the input excitation voltage command Vdcom and torque voltage command Vqcom are converted into U-phase voltage commands Vu, V. The phase voltage command Vv and the W phase voltage command Vw are converted.

  The base signal generator 12 generates an on / off signal for each switching element of the inverter circuit 3 based on the U-phase voltage command Vu, the V-phase voltage command Vv, and the W-phase voltage command Vw that are converted and output by the coordinate converter 7. Output to the inverter circuit 3. As a result, AC power is supplied to the motor 1 and the motor 1 is rotationally driven.

  As described above, the speed control system for causing the rotational speed command ωmcom to follow the rotational speed command ωmFB so that the speed deviation between the rotational speed command ωmcom of the external input and the detected rotational speed ωmFB becomes small. Is a minor loop (feedback loop entering further inside), and a speed control system including a speed controller 14 (a speed control system in a narrow sense, hereinafter referred to as a “narrow sense”). The speed control system is called a major loop (feedback loop entering outside), and the speed control system and the torque current control system in the narrow sense are configured by cascade control in this order.

  Further, the estimated magnetic flux ΦS is caused to follow the magnetic flux delay correction command Φhcom so that the magnetic flux deviation between the magnetic flux lag correction command Φhcom generated by the magnetic flux lag compensator 16a from the externally input magnetic flux command Φcom and the estimated magnetic flux ΦS becomes small. The magnetic flux control system includes an exciting current control system including the exciting current controller 10 as a minor loop and a magnetic flux control system including a magnetic flux controller 13 (a magnetic flux control system in a narrow sense, hereinafter referred to as “ "Narrowly defined magnetic flux control system") is a major loop, and the narrowly defined magnetic flux control system and exciting current control system are configured by cascade control in this order. Hereinafter, the main part will be specifically described.

First, the transfer function Gid_Φ (s) of the magnetic flux estimation unit 8 having the function of estimating and calculating the estimated magnetic flux ΦS from the excitation current idFB is the secondary resistance Rr of the rotor of the motor 1 and the self-inductance Lr of the rotor of the motor 1. Using the mutual inductance M between the windings of the motor 1 and the Laplace operator s, it can be expressed by equation (1).
Gid_Φ (s) = M / (1 + s · (Lr / Rr)) (1)

Next, the magnetic flux controller 13 will be described. The magnetic flux controller 13 is a part that determines the response band of the magnetic flux control system. The transfer function GΦ (s) of the magnetic flux controller 13 when the magnetic flux controller 13 constitutes a PI control system, for example, can be expressed by Expression (2) using a proportional gain KΦ and an integral gain KΦi.
GΦ (s) = KΦ + KΦi / s (2)

Here, the constants used for the proportional gain KΦ and integral gain KΦi in the PI control system are composed of a fixed value portion that depends on the inductance and winding resistance of the motor 1 and a variable value portion that depends on the so-called gain. Therefore, in the present specification, the variable value portion is referred to as a response band constant wc of the magnetic flux controller 13, and the proportional gain KΦ is set as shown in Expression (3) using this response band constant wc. Further, the integral gain KΦi is set as shown in Expression (4).
KΦ = wc · Lr / (Rr · M) (3)
KΦi = wc / M (4)

  From equations (2), (3), and (4), the magnetic flux controller 13 can increase or decrease the proportional gain KΦ and the integral gain KΦi by increasing or decreasing the set value of the response band constant wc. That is, when the response band constant wc is increased, the proportional gain KΦ and the integral gain KΦi are increased, and the response band of the magnetic flux control system can be widened. Thus, the response band constant wc of the magnetic flux controller 13 is a constant that determines the magnitude of the response band of the magnetic flux control system.

  The relationship between the response band of the magnetic flux control system and the exciting current limiter 23 will be described. As described above, the magnetic flux control system has cascade control with the exciting current control system as a minor loop and the narrowly defined magnetic flux control system as a major loop. Generally, the response of the exciting current control system, which is a minor loop, is configured. If the band can be widened, the response band constant wc of the magnetic flux controller 13 can be increased, and the response band of the magnetic flux control system can be widened.

  On the other hand, the excitation current limiter 23 has a function of limiting the output value of the magnetic flux controller 13 as described above, and uses the output value of the excitation current limiter 23 as the excitation current command idcom. This is provided because of the restriction on the allowable maximum current value of the inverter circuit 3 that supplies power to the motor 1.

  FIG. 2 is a diagram for explaining the behavior of the magnetic flux control system including the magnetic flux controller 13 and the exciting current limiter 23 shown in FIG. 1, and FIGS. 2 (a1) and 2 (a2) show the case where the response band is widened. The operating characteristics are shown, and FIGS. 2B1 and 2B2 show the operating characteristics when the response band is not widened.

  2A1 and 2A2 will be described. When the response band constant wc of the magnetic flux controller 13 is increased and the response band of the magnetic flux control system is expanded, the excitation current command idcom is clamped as shown in FIG. This indicates that the output value of the magnetic flux controller 13 is larger than the output upper limit value of the excitation current limiter 23, and the excitation current command idcom is limited by the excitation current limiter 23. In such a case, as shown in FIG. 2 (a2), there arises a problem that the magnetic flux Φ overshoots the magnetic flux command Φcom, and the time for the magnetic flux Φ to reach the magnetic flux command Φcom is delayed.

  2 (b1) and 2 (b2) will be described. When the response band constant wc of the magnetic flux controller 13 is not increased and the response band of the magnetic flux control system is not expanded, the excitation current command idcom is not clamped as shown in FIG. This is because the output value of the magnetic flux controller 13 is smaller than the output upper limit value of the excitation current limiter 23 and larger than the output lower limit value of the excitation current limiter 23. It is used as a current command idcom. In such a case, as shown in FIG. 2 (b2), the magnetic flux Φ does not overshoot the magnetic flux command Φcom, but the tracking of the magnetic flux Φ with respect to the magnetic flux command Φcom is delayed as in FIG. 2 (a2).

  From the above, even if the response band of the excitation current control system, which is a minor loop, can be expanded, if the excitation current limiter 23 is included inside the magnetic flux control system, the magnetic flux command can be increased by expanding the response band of the magnetic flux control system. Magnetic flux Φ overshoots Φcom. Therefore, it is difficult to widen the response band of the magnetic flux control system, and it is difficult to speed up the follow-up of the magnetic flux Φ with respect to the magnetic flux command Φcom.

  Therefore, in the first embodiment, as shown in FIG. 1, the magnetic flux lag compensator 16a is provided, the response band constant wc of the magnetic flux controller 13 is not increased, and the tracking delay of the magnetic flux Φ with respect to the magnetic flux command Φcom generated thereby. Is corrected by the magnetic flux lag compensator 16a.

As described above, the excitation current limiter 23 has a function of limiting the excitation current command idcom to be output with respect to the output of the input magnetic flux controller 13. When the output upper limit value is idmax and the output lower limit value is idmin, the excitation current command idcom output from the excitation current limiter 23 can be expressed as in Expression (5).
idmin ≦ idcom ≦ idmax (5)

  Next, the magnetic flux lag compensator 16a will be described. FIG. 3 is a block diagram showing a configuration example of the magnetic flux lag compensator shown in FIG. As shown in FIG. 3, for example, the magnetic flux lag compensator 16a includes an adder 25, filters 26 and 27, a multiplier 28, and a limiter 29 as output limiting means.

  The filters 26 and 27 can be composed of various filters such as an FIR filter and an IIR filter. The gain used in the multiplier 28 is assumed to be a positive real number. The limiter 29 has a function of limiting the output of the input signal. For example, when the input signal increases, a value less than or equal to the maximum value set for the output upper limit value is output, and when the input signal decreases, a value greater than or equal to the minimum value set for the output lower limit value Is output.

  The magnetic flux command Φcom from the outside is input to the filters 26 and 27 in this order, filtered by each, and then multiplied by the gain by the multiplier 28. Then, the magnetic flux command value Φcom and the output of the multiplier 28 are input to the adder 25 and added, and the limiter 29 extracts the magnetic flux command within the limit value from the added magnetic flux command Φ1com output by the adder 25. , This is a magnetic flux lag correction command Φhcom output from the magnetic flux lag compensator 16a.

The operation of the magnetic flux lag compensator 16a configured as described above will be described.
The transfer function of the filter 26 is the reciprocal “1 / Gid_Φ (s)) of the transfer function Gid_Φ (s) of the magnetic flux estimator 8, and the transfer function of the filter 27 is the reciprocal of the transfer function GΦ (s) of the magnetic flux controller 13“ When 1 / GΦ (s) ”is set and the gain of the multiplier 28 is set to 1, the transfer function Go1 (s) from the filter 26 to the multiplier 28 is expressed by the following equation (6).
Go1 (s)
= 1 / Gid_Φ (s) × 1 / GΦ (s) × 1
= (1 + s · (Lr / Rr)) / M × s / (KΦ · s + KΦi) × 1
= (1 + s · (Lr / Rr)) / M × s / (wc · Lr / (Rr · M) · s + wc / M)
= S / wc (6)

The added magnetic flux command Φ1com output from the adder 25 is obtained by adding the magnetic flux command Φcom and the output of the multiplier 28, and is expressed by the following equation (7).
Φ1com = (1 + Go1 (s)) · Φcom
= (1 + s / wc) · Φcom (7)

As described above, the limiter 29 outputs the magnetic flux lag correction command Φhcom based on the input additional magnetic flux command Φ1com. When the output upper limit value of the limiter 29 is Φhmax and the output lower limit value is Φhmin, the magnetic flux lag correction command Φhcom can be expressed by Expression (8).
Φhmin ≦ Φhcom ≦ Φhmax (8)

If the output upper limit value Φhmax of the limiter 29 is the magnetic flux command Φcom, the magnetic flux lag correction command Φhcom output from the limiter 29 is expressed by the following formula (9) or formula (10).
Φ1com <Φcom: Φhcom = Φ1com (9)
Φ1com ≧ Φcom: Φhcom = Φcom (10)

That is, the addition magnetic flux command Φ1com output from the adder 25 is compared with the magnetic flux command Φcom.
Φ1com <Φcom
When the relationship is, the magnetic flux delay correction command Φhcom output from the limiter 29 is the same value as the additional magnetic flux command Φ1com output from the adder 25 (Equation (9)). Alternatively, the added magnetic flux command Φ1com output from the adder 25 is compared to the magnetic flux command Φcom.
Φ1com ≧ Φcom
When the relationship is, the magnetic flux delay correction command Φhcom output from the limiter 29 is the same value as the externally input magnetic flux command Φcom (formula (10)).

If the output lower limit value Φhmin of the limiter 29 is the magnetic flux lower limit value Φmin (for example, the minimum magnetic flux required to drive the motor 1), the magnetic flux delay correction command Φhcom output from the limiter 29 is expressed by the following equation ( 11) or the formula (12).
Φ1com> Φmin: Φhcom = Φ1com (11)
Φ1com ≦ Φmin: Φhcom = Φcommin (12)

That is, the addition magnetic flux command Φ1com output from the adder 25 is smaller than the magnetic flux lower limit value Φmin.
Φ1com> Φmin
, The magnetic flux delay correction command Φhcom output from the limiter 29 is the same value as the added magnetic flux command Φ1com output from the adder 25 ((Equation 11)). Alternatively, the addition magnetic flux command Φ1com output from the adder 25 is smaller than the magnetic flux lower limit value Φmin.
Φ1com ≦ Φmin
When the relationship is, the magnetic flux delay correction command Φhcom output from the limiter 29 becomes the magnetic flux lower limit value Φmin ((Equation 12)).

From the above, from Equation (9), Equation (10), Equation (11), and Equation (12), Equation (8) can be replaced with the following Equation (13).
Φmin ≦ Φhcom ≦ Φcom (13)

  According to this method, the limiter 29 increases the magnetic flux command Φcom stepwise so as to switch from the non-excited state to the excited state, or the load increases stepwise and the magnetic flux command Φcom increases stepwise. Even in the case of a change, the magnetic flux delay correction command Φhcom can be limited so as not to exceed the magnetic flux command Φcom. Further, even when the load decreases stepwise and the magnetic flux command Φcom changes stepwise in the decreasing direction, the magnetic flux delay correction command Φhcom can be limited so as not to fall below the magnetic flux lower limit value Φmin.

  The magnetic flux delay correction command Φhcom is a command obtained by adding the tracking delay generated by the response band of the magnetic flux control system to the magnetic flux command Φcom. When a transient change is large when the magnetic flux command Φcom increases, the magnetic flux lag correction command Φhcom becomes a larger value than the magnetic flux command Φcom, and the magnetic flux Φ may overshoot the magnetic flux command Φcom. Therefore, by adding the addition magnetic flux command Φ1com, which is the output of the adder 25, to the limiter 29, the magnetic flux lag correction command Φhcom is prevented from becoming an excessive value, so that the magnetic flux Φ does not overshoot the magnetic flux command Φcom. I have to.

  Note that the transfer characteristic of the filter 26 is described as a transfer characteristic indicated by the reciprocal of the transfer function of the magnetic flux estimator 8, and the transfer characteristic of the filter 27 is a transfer characteristic indicated by the reciprocal of the transfer function of the magnetic flux controller 13. However, it may be a transfer characteristic approximating the reciprocal of each transfer function.

  Next, with reference to FIG. 4 and FIG. 5, the effect by providing the magnetic flux lag compensator 16a will be described. FIG. 4 is a diagram illustrating characteristics of a motor to be controlled. FIG. 5 is a diagram for explaining the control characteristics of the motor with and without the magnetic flux lag compensator shown in FIG.

  First, in order to confirm the effect of adding the magnetic flux lag compensator 16a, the characteristics of the motor 1 to be controlled will be described with reference to FIG. In FIG. 4A, the rotational speed-output characteristics are shown with the horizontal axis as the rotational speed and the vertical axis as the output. FIG. 4B shows a rotational speed-torque characteristic in which the horizontal axis is the rotational speed and the vertical axis is the torque. FIG. 4C shows the rotational speed-magnetic flux characteristics with the horizontal axis as the rotational speed and the vertical axis as the magnetic flux. FIG. 4D shows a rotational speed-torque current characteristic in which the horizontal axis is the rotational speed and the vertical axis is the torque current.

  As shown in FIGS. 4A and 4B, in the vector control of the motor 1 that is an induction motor, the upper limit determined by the electrical constant of the induction motor, such as winding resistance and inductance, and the voltage of the capacitor 4 serving as a power source. Up to the rotational speed (base rotational speed) ωb until the voltage is reached, the constant torque drive region 40 is maintained, and the magnetic flux is kept constant and constant torque driving is performed. Then, when the rotational speed ωb reaching the upper limit voltage is reached, the constant output drive region 41 is subsequently obtained, and the magnetic flux is reduced in inverse proportion to the rotational speed to be increased. As a result, torque is also reduced, and driving with a constant output is performed.

  The characteristics of the motor 1 include the motor base rotational speed ωb determined by the upper limit voltage of the motor, the motor maximum rotational speed ωmax, the motor maximum torque Tmax, the motor maximum output Pout, and the load inertia Jm.

  The operating conditions of the motor 1 are as follows. The motor 1 is in a non-excited state before driving, and the magnetic flux is zero. Since the motor 1 changes from the non-excited state to the excited state during driving, the magnetic flux command Φcom changes substantially in a step shape. A load torque such as a friction load is set to zero. In this state, the motor 1 is accelerated from a rotational speed 0 to a motor maximum rotational speed ωmax.

  In FIG. 5A, the horizontal axis is time, the vertical axis is the rotational speed ω, and in the constant torque drive region 40 shown in FIG. 4A, a magnetic flux delay compensator 16a is provided. The rise characteristic 42 of the rotation speed in the case of “with the device” and the rise characteristic 43 of the rotation speed in the case of “without the magnetic flux delay compensator” without the magnetic flux delay compensator 16a are shown. As shown in FIG. 5 (a), by providing the magnetic flux lag compensator 16a, the follow-up becomes faster in the constant torque drive region at the start of motor drive, so that the rotational speed increases rapidly and the acceleration characteristics are improved. I understand.

  In FIG. 5B, the horizontal axis is time, the vertical axis is the magnetic flux Φ, and the magnetic flux (that is, the magnetic flux command) when the magnetic flux lag compensator 16a is not provided in the constant output drive region 41 shown in FIG. A decrease change characteristic 44 of [Phi] com) and a decrease change characteristic 45 of the magnetic flux (that is, the magnetic flux delay correction command [Phi] hcom) when the magnetic flux delay compensator 16a is provided are shown.

  When the magnetic flux lag compensator 16a cannot increase the gain of the magnetic flux controller 13 with respect to the magnetic flux command Φcom and the response band of the magnetic flux control system cannot be widened, considering that the tracking of the magnetic flux Φ is delayed, The delay is corrected in advance by the filters 26 and 27 and the multiplier 28 and added to the magnetic flux command Φcom, and the magnetic flux lag correction command Φhcom is generated via the limiter 29. As described above, since the delay is corrected in advance in consideration of the delay of the follow-up of the magnetic flux Φ, as shown in FIG. 5B, the magnetic flux lag correction command Φhcom is transiently large. When changing, it shows a characteristic that changes more greatly than the magnetic flux command Φcom.

  In FIG. 5C, in order to confirm the followability of the estimated magnetic flux Φ when the magnetic flux lag compensator 16a is not provided, the horizontal axis is time, the vertical axis is the magnetic flux, the change characteristic 46 of the magnetic flux command Φcom, and the magnetic flux A change characteristic 47 of Φ is shown. As shown in FIG. 5C, when the magnetic flux lag compensator 16a is not provided, the magnetic flux Φ estimated in the constant output drive region is delayed with respect to the magnetic flux command Φcom.

  In FIG. 5D, in order to confirm the followability of the estimated magnetic flux Φ when the magnetic flux lag compensator 16a is provided, the horizontal axis is time, the vertical axis is the magnetic flux, the change characteristic 48 of the magnetic flux command Φcom, and the magnetic flux A change characteristic 49 of Φ is shown. As shown in FIG. 5D, when the magnetic flux lag compensator 16a is provided, the magnetic flux Φ estimated in the constant output drive region follows the magnetic flux command Φcom without delay.

  From FIG. 5, it can be seen that by providing the magnetic flux delay compensator 16a, the estimated delay of the magnetic flux Φ with respect to the magnetic flux command Φcom is corrected in both the constant torque drive region 40 and the constant output drive region 41. In the constant torque drive region 40, the predetermined torque is quickly reached, and in the constant output drive region 41, the magnetic flux Φ can be reduced according to the magnetic flux command Φcom, so that the rotational speed is rapidly increased. Therefore, it can be seen that the acceleration time up to the maximum motor rotation speed ωmax is shortened.

  Even when there is a torque fluctuation due to a load fluctuation during machining at a constant speed in a machine tool to which the motor control device according to the first embodiment is applied, the magnetic flux lag compensator 16a acts to change the magnetic flux command. As a main axis of the machine tool, there is an effect that it contributes to an improvement in control performance.

  As an effect in the case of providing the magnetic flux lag compensator 16a, it is also possible to change the constant of the limiter 29 so as to speed up the rise of the magnetic flux when switching from the non-excited state to the excited state. For example, if the output upper limit value of the limiter 29 is set to a value larger than the magnetic flux command Φcom, and the magnetic flux lag correction command Φhcom can output a value larger than the magnetic flux command Φcom, The follow-up becomes faster and the rise of magnetic flux can be made faster.

  Although FIG. 1 shows a case where the magnetic flux lag correction command Φhcom generated by the magnetic flux lag compensator 16a is input to the addition input terminal (+) of the subtractor 20, this is not restrictive. That is, in FIG. 1, the external input magnetic flux command Φcom is input to the addition input terminal (+) of the subtracter 20 as before, and the configurations of the filters 26 and 27 and the multiplier 28 constituting the magnetic flux lag compensator 16a. The magnetic flux lag correction command Φhcom generated by changing the constants as follows is added to the output of the magnetic flux controller 13 and input to the exciting current limiter 23. Also with this configuration, the delay of the magnetic flux can be corrected similarly.

  The purpose of the magnetic flux lag compensator 16a is to correct the delay of the magnetic flux Φ with respect to the transient change of the magnetic flux command Φcom, so that the correction at the steady time after a sufficient time has passed needs to be zero. However, in the configuration shown in FIG. 1, extra correction is performed in a steady state.

  Therefore, the magnetic flux lag compensator 16a generates a magnetic flux lag correction command Φhcom indicating a certain correction amount when the magnetic flux command Φcom changes transiently, and generates a magnetic flux lag correction command Φhcom indicating zero correction amount in a steady state. Configure to generate. This can be realized by changing the configurations and constants of the filters 26 and 27 and the multiplier 28 constituting the magnetic flux lag compensator 16a. Therefore, as described above, the magnetic flux delay compensation command Φhcom generated by the magnetic flux delay compensator 16 a can be added to the output of the magnetic flux controller 13 and input to the exciting current limiter 23.

Embodiment 2. FIG.
FIG. 6 is a block diagram showing a main configuration of the motor control apparatus according to Embodiment 2 of the present invention. In FIG. 6, components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1) are given the same reference numerals. Here, the description will be focused on the portion related to the second embodiment.

  6, in the motor control apparatus according to the second embodiment, in the configuration shown in FIG. 1 (the first embodiment), a magnetic flux delay compensator 16b is provided instead of the magnetic flux delay compensator 16a, and an adder is provided. 24 is provided between the magnetic flux controller 13 and the exciting current limiter 23.

  The magnetic flux lag compensator 16b generates a model excitation current command idmcom and a model magnetic flux command Φmcom from an externally input magnetic flux command Φcom, for example, with the configuration shown in FIG.

  The model excitation current command idmcom which is one output of the magnetic flux lag compensator 16 b is input to one addition input terminal (+) of the adder 24. The other addition input of the adder 24 is an output of the magnetic flux controller 13, and an output of the adder 24 is input to the exciting current limiter 23. As a result, the model excitation current command idmcom is reflected in the excitation current command idcom output by the excitation current limiter 23. That is, the model excitation current command idmcom corresponds to the second magnetic flux delay correction command in claim 3.

  The model magnetic flux command Φmcom, which is the other output of the magnetic flux lag compensator 16b, is input to the plus input terminal (+) of the subtractor 20 instead of the magnetic flux lag correction command Φhcom shown in FIG. Therefore, the output of the subtracter 20 (input of the magnetic flux controller 13) is a deviation (magnetic flux deviation) between the model magnetic flux command Φmcom and the estimated magnetic flux Φ. Therefore, the model magnetic flux command Φmcom corresponds to the first magnetic flux delay correction command in claim 3.

  Next, FIG. 7 is a block diagram showing a configuration example of the magnetic flux lag compensator shown in FIG. For example, as shown in FIG. 7, the magnetic flux lag compensator 16b is configured by a subtracter 30 and an ideal model of the motor 1 (which can be regarded as having no errors or variations in motor constants such as winding resistance and inductance). The model magnetic flux controller 31 and the model magnetic flux estimation unit 32 constitute a feedback control system (hereinafter referred to as “model magnetic flux control system”). In the model magnetic flux control system, the excitation current control system, which is a minor loop, has a sufficiently wide response band, and the transfer function of the excitation current control system can be regarded as 1.

  The magnetic flux command Φcom is input to the positive input terminal (+) of the subtracter 30, and the model magnetic flux command Φmcom output from the model magnetic flux estimating unit 32 is FB (feedback signal) to the negative input terminal (−) of the subtractor 30. ). The model magnetic flux controller 31 obtains a model excitation current command idmcom which is one output of the magnetic flux lag compensator 16b from the output (magnetic flux deviation) of the subtractor 30. The model magnetic flux estimator 32 obtains a model magnetic flux command Φmcom, which is the other output of the magnetic flux lag compensator 16b, from the model excitation current command idmcom output from the model magnetic flux controller 31. This will be specifically described below.

In order to make the characteristic of the model magnetic flux estimation unit 32 the same as that of the magnetic flux estimation unit 8, it is assumed that the transfer function Gmid_Φ (s) of the model magnetic flux estimation unit 32 is given by Expression (14).
Gmid_Φ (s) = M / (1 + s · (Lr / Rr)) (14)

The model magnetic flux controller 31 is a part that determines the response band of the model magnetic flux control system, and is configured by PI control like the magnetic flux controller 13. The transfer function Gm [Phi] (s) of the model magnetic flux controller 31 is expressed as in Expression (15) using the model proportional gain Km [Phi] and the model integral gain Km [Phi] i.
GmΦ (s) = KmΦ + KmΦi / s (15)

Here, the constants used for the model proportional gain KmΦ and the model integral KmΦi in the PI control are fixed value portions that depend on the inductance of the motor 1 and the winding resistance, similarly to the proportional gain KΦ and integral gain KΦi of the magnetic flux controller 13. And a variable value portion that depends on the gain, the variable portion is referred to as a response band constant wmc of the model magnetic flux controller 31 in this specification, and the model is also obtained using this response band constant wmc. The proportional gain KmΦ is set as shown in Expression (16), and the model integral gain KmΦi is set as shown in Expression (17).
KmΦ = wmc · Lr / (Rr · M) (16)
KmΦi = wmc / M (17)

Note that the response band constant wmc of the model magnetic flux controller 31 is set, for example, as shown in Expression (18) with respect to the response band constant wc of the magnetic flux controller 13.
wmc = 2 × wc (18)

  Next, the effect obtained by providing the magnetic flux lag compensator 16b will be described with reference to FIG. FIG. 8 is a diagram for explaining the control characteristics of the motor with and without the magnetic flux lag compensator shown in FIG. The operating conditions for the motor 1 to be controlled are as described in the first embodiment.

  In FIG. 8A, the horizontal axis is time, the vertical axis is the rotational speed, and in the case of “with magnetic flux delay compensator” in which the magnetic flux delay compensator 16b is provided in the constant torque drive region 40 shown in FIG. A rotational speed rising characteristic 50 and a rotational speed rising characteristic 51 in the case of “no magnetic flux lag compensator” without the magnetic flux lag compensator 16b are shown. As in FIG. 5A, it is shown that acceleration characteristics are improved.

  In FIG. 8B, in order to confirm the followability of the magnetic flux Φ when the magnetic flux lag compensator 16b is not provided, the horizontal axis is time, the vertical axis is the magnetic flux, the change characteristic 52 of the magnetic flux command Φcom, and the magnetic flux Φ A change characteristic 53 is shown. As shown in FIG. 8B, when the magnetic flux lag compensator 16b is not provided, the follow-up of the magnetic flux Φ with respect to the magnetic flux command Φcom is delayed.

  In FIG. 8C, in order to confirm the followability of the magnetic flux Φ when the magnetic flux lag compensator 16b is provided, the horizontal axis is time, the vertical axis is the magnetic flux, the change characteristic 54 of the magnetic flux command Φcom, and the magnetic flux Φ A change characteristic 55 is shown. As shown in FIG. 8C, when the magnetic flux lag compensator 16b is provided, the follow-up of the magnetic flux Φ with respect to the magnetic flux command Φcom is fast. As a result, as shown in FIG. 8A, the acceleration is accelerated in the constant torque drive region, and the rotational speed is rapidly increased also in the constant output drive region.

  From FIG. 8, it can be seen that by providing the magnetic flux delay compensator 16b, the estimated delay of the magnetic flux Φ with respect to the magnetic flux command Φcom is corrected in both the constant torque drive region 40 and the constant output drive region 41 shown in FIG. . This is because the model response band constant wmc of the model magnetic flux controller 31 which is a constituent element of the magnetic flux lag compensator 16b can be increased as shown in the equation (18). It can be seen that acceleration characteristics up to ωmax are also improved.

  As described above, the magnetic flux control system is configured by cascade control in which a narrow-sense magnetic flux control system including the magnetic flux controller 13 is a major loop and an exciting current control system is a minor loop. When the influence of current detection delay, coordinate conversion delay, conversion error, or the like in the excitation current control system, which is a minor loop, is large, the response band constant wc of the magnetic flux controller 13 is increased to impair control stability of the magnetic flux control system. In some cases, the response band of the magnetic flux control system cannot be expanded. In this case, there is a problem that the follow-up of the magnetic flux with respect to the magnetic flux command is delayed.

  In response to this problem, according to the second embodiment, the response band constant wmc of the model magnetic flux controller 31 in the magnetic flux lag compensator 16b is set to a value larger than the response band constant wc of the magnetic flux controller 13. Therefore, the control stability of the magnetic flux control system can be ensured by the magnetic flux controller 13, and the followability of the magnetic flux with respect to the magnetic flux command can be improved by the model magnetic flux controller 31 in the magnetic flux delay compensator 16b.

Embodiment 3 FIG.
FIG. 9 is a block diagram showing another configuration example of the magnetic flux lag compensator shown in FIG. 6 as Embodiment 3 of the present invention. FIG. 10 is a block diagram illustrating a configuration example of the feedforward compensator illustrated in FIG. The magnetic flux lag compensator 16c shown in FIG. 9 is used in place of the magnetic flux lag compensator 16b shown in FIG. 6. Therefore, the motor controller to which the magnetic flux lag compensator 16c is applied is as shown in FIG. Yes.

  As shown in FIG. 9, the magnetic flux lag compensator 16 c is the same as the magnetic flux lag compensator 16 b shown in FIG. 6, and the feedforward compensator 33 is connected to the positive input terminal (+) of the subtractor 30. It is inserted in the input path.

  Therefore, the subtracter 30 outputs a deviation (magnetic flux deviation) between the magnetic flux feedforward command Φfcom output from the feedforward compensator 33 and the model magnetic flux command Φmcom output from the model magnetic flux estimation unit 32 to the model magnetic flux controller 31. It will be.

  The outputs of the magnetic flux lag compensator 16c are two, that is, the model excitation current command idmcom and the model magnetic flux command Φmcom, similarly to the magnetic flux lag compensator 16b. They are input to the adder 24 and the subtractor 20 in the same manner as the output of the magnetic flux lag compensator 16b. However, since the feedforward compensator 33 is provided, the output content thereof is the same as that of the magnetic flux lag compensator 16b. Is different.

  Next, the feedforward compensator 33 will be described. For example, as shown in FIG. 10, the feedforward compensator 33 includes filters 34 and 35, a multiplier 36, an adder 37, and a limiter 38. The filters 34 and 35 can be composed of various filters such as FIR filters and IIR filters. The gain used in the multiplier 36 is assumed to be a positive real number. The limiter 38 has a function similar to that of the limiter 29 described in the first embodiment, and has a function of limiting the output of an input signal. For example, when the input signal increases, a value less than or equal to the maximum value set for the output upper limit value is output, and when the input signal decreases, a value greater than or equal to the minimum value set for the output lower limit value Is output.

  In FIG. 10, an externally input magnetic flux command Φcom is input to the filters 34 and 35 in this order, filtered by each, and then multiplied by a gain by a multiplier 36. Then, the magnetic flux command Φcom and the output of the multiplier 36 are input to the adder 37 and added, and the limiter 38 takes out the magnetic flux command within the limit value from the added magnetic flux command Φ2com output by the adder 37. Is a magnetic flux feedforward command Φfcom output by the feedforward compensator 33.

The operation of the magnetic flux lag compensator 16a configured as described above will be described.
The transfer function of the filter 34 is the reciprocal “1 / Gmid_Φ (s)” of the transfer function Gmid_Φ (s) of the model magnetic flux estimator 32, and the transfer function of the filter 35 is the reciprocal of the transfer function GmΦ (s) of the model magnetic flux controller 31. When “1 / GmΦ (s)” is set and the gain of the multiplier 36 is 1, the transfer function Go2 (s) from the filter 34 to the multiplier 36 is expressed by Expression (19).
Go2 (s)
= 1 / Gmid_Φ (s) × 1 / GmΦ (s) × 1
= (1 + s · (Lr / Rr)) / M × s / (KΦ · s + KΦi) × 1
= (1 + s · (Lr / Rr)) / M × s / (wmc · Lr / (Rr · M) · s + wmc / M)
= S / wmc (19)

The added magnetic flux command Φ2com output from the adder 37 is obtained by adding the magnetic flux command value Φcom and the output of the multiplier 36, and is represented by Expression (20).
Φ2com = (1 + Go2 (s)) · Φcom
= (1 + s / wmc) · Φcom (20)

As described above, the limiter 38 outputs the magnetic flux feedforward command Φfcom based on the input additional magnetic flux command Φ2com. When the output upper limit value is Φfmax and the output lower limit value is Φfmin, the magnetic flux feedforward command Φfcom can be expressed by Expression (21).
Φfmin ≦ Φfcom ≦ Φfmax (21)

If the output upper limit value Φfmax of the limiter 38 is the magnetic flux command Φcom, the magnetic flux feedforward command Φhcom output from the limiter 38 is expressed by the following formula (22) or formula (23).
Φ2com <Φcom: Φfcom = Φ2com (22)
Φ2com ≧ Φcom: Φfcom = Φcom (23)

That is, the addition magnetic flux command Φ2com output from the adder 37 is compared to the magnetic flux command Φcom.
Φ2com <Φcom
In this case, the magnetic flux feedforward command Φfcom output from the limiter 38 is the same value as the added magnetic flux command Φ2com output from the adder 37 (formula (22)). Further, the addition magnetic flux command Φ2com output from the adder 37 is compared to the magnetic flux command Φcom.
Φ2com ≧ Φcom
In this case, the magnetic flux feedforward command Φfcom output from the limiter 38 has the same value as the externally input magnetic flux command Φcom (formula (23)).

When the output minimum value Φhmin of the limiter 38 is the magnetic flux lower limit value Φmin, the magnetic flux feedforward command Φfcom output from the limiter 37 is expressed by the following formula (24) or formula (25).
Φ2com> Φmin: Φfcom = Φ2com (24)
Φ2com ≦ Φmin: Φfcom = Φcom (25)

That is, the addition magnetic flux command Φ2com output from the adder 37 is smaller than the magnetic flux lower limit value Φcommin.
Φ2com> Φmin
In this case, the magnetic flux feedforward command Φhcom output from the limiter 38 has the same value as the added magnetic flux command Φ2com output from the adder 37 (formula (24)). Alternatively, the addition magnetic flux command Φ2com output from the adder 37 is smaller than the magnetic flux lower limit value Φmin.
Φ2com ≦ Φmin
In this case, the magnetic flux feedforward command Φfcom output from the limiter 38 becomes the magnetic flux lower limit value Φmin (formula (25)).

From the above, from equation (22), equation (23), equation (24), and equation (25), equation (21) can be replaced by the following equation (26).
Φmin ≦ Φfcom ≦ Φcom (26)

  According to this method, when the magnetic flux command Φcom increases stepwise so as to switch from the non-excited state to the excited state, the limiter 38 increases the load stepwise and the magnetic flux command Φcom increases stepwise. Even if it changes, the magnetic flux feedforward command Φfcom can be limited so as not to exceed the magnetic flux command Φcom. Further, even when the load decreases stepwise and the magnetic flux command Φ changes stepwise in the decreasing direction, the magnetic flux feedforward command Φfcom can be limited so as not to fall below the magnetic flux lower limit value Φmin.

  The magnetic flux feedforward command Φfcom adds the tracking delay generated by the response band of the model magnetic flux control system configured inside the magnetic flux lag compensator 16c determined by the response band constant wmc of the model magnetic flux controller 31 to the magnetic flux command Φcom. Command. When the magnetic flux command Φcom increases, if a transient change is large, the magnetic flux feedforward command Φfcom becomes a larger value than the magnetic flux command Φcom, and the magnetic flux Φ may overshoot the magnetic flux command Φcom. Therefore, by adding the added magnetic flux command Φ2com, which is the output of the adder 37, to the limiter 38, the magnetic flux feedforward command Φfcom is prevented from becoming an excessive value, and the magnetic flux Φ does not overshoot the magnetic flux command Φcom. I have to.

  The filter 34 is described as having a transfer characteristic indicated by the reciprocal of the transfer function of the model magnetic flux estimator 32, and the transfer characteristic of the filter 35 is assumed to be a transfer characteristic indicated by the reciprocal of the transfer function of the model magnetic flux controller 31. As described above, the transfer characteristic may be an approximation of the inverse of each transfer function.

  Next, with reference to FIG. 11, the effect by providing the magnetic flux lag compensator 16c will be described. FIG. 11 is a diagram for explaining the control characteristics of the motor when the magnetic flux lag compensator shown in FIG. 9 is provided and when the magnetic flux lag compensator shown in FIG. 7 is provided. The operating conditions for the motor 1 to be controlled are as described in the first embodiment.

  In FIG. 11A, the horizontal axis is time, the vertical axis is the rotation speed, and in the constant torque drive region 40 shown in FIG. 3, a feedforward compensator is provided (that is, the magnetic flux lag compensator 16c is provided). In the case of the case (without the feedforward compensator), and the rise characteristic 57 of the rotational speed in the case where the feedforward compensator is not provided (that is, when the magnetic flux delay compensator 16b is provided).

  In FIG. 11B, in order to confirm the follow-up speed of the magnetic flux Φ without the feedforward compensator (that is, when the magnetic flux lag compensator 16b is provided, the horizontal axis is time, the vertical axis is magnetic flux, A change characteristic 58 of the magnetic flux command Φcom and a change characteristic 59 of the magnetic flux Φ are shown.

  FIG. 11 (c) shows time in the horizontal axis and magnetic flux in the vertical axis in order to confirm the follow-up speed of the magnetic flux Φ in the case where there is a feedforward compensator (that is, when the magnetic flux delay compensator 16c is provided). A change characteristic 60 of the magnetic flux command Φcom and a change characteristic 61 of the magnetic flux Φ are shown.

  From FIG. 11, by providing the magnetic flux lag compensator 16c with the feed-forward compensator 33 added to the magnetic flux lag compensator 16b, (a) the rising of the magnetic flux Φ with respect to the magnetic flux command Φcom is performed quickly. 3) Also in the constant output drive region 41 shown in FIG. 3, since the magnetic flux Φ follows the magnetic flux command Φcom, the rotational speed is rapidly increased, and the acceleration characteristic is improved. Can understand.

  In short, the comparison between FIG. 8 and FIG. 11 shows that the follow-up of the magnetic flux Φ with respect to the magnetic flux command Φcom is provided with the magnetic flux lag compensator 16c as compared with the second embodiment (FIG. 8) provided with the magnetic flux lag compensator 16b. It can be seen that the third embodiment (FIG. 11) is improved.

  As described above, according to the first to third embodiments, the delay of the magnetic flux with respect to the magnetic flux command can be corrected, so that the followability of the magnetic flux is improved, and a predetermined torque is obtained in a wide operation region including acceleration / deceleration and load torque fluctuation. Can be output. As a result, the acceleration performance and control performance of the motor can be improved.

  As described above, the motor control device according to the present invention can correct the follow-up delay of the magnetic flux with respect to the magnetic flux command and output the predetermined torque to the induction motor in a wide operation region including acceleration / deceleration and load torque fluctuation. It is useful as a motor control device that can improve the acceleration performance and control performance of an induction motor, and is particularly suitable for a motor control device that drives an induction motor used in a spindle of a machine tool, a vehicle, or the like.

1 Motor (induction motor)
2 Speed detector 3 Inverter circuit 4 Capacitor 5 Current detector 6 Coordinate converter (UV-dq)
7 Coordinate converter (dq-UVW)
DESCRIPTION OF SYMBOLS 8 Magnetic flux estimation part 9 Sliding speed calculation part 10 Excitation current controller 11 Torque current controller 12 Base signal generation part 13 Magnetic flux controller 14 Speed controller 15 Integrator 16a, 16b, 16c Magnetic flux delay compensator 17, 18, 20, 21, 30 Subtractor 19, 24, 25, 37 Adder 22 Torque current limiter 23 Excitation current limiter 26, 27, 34, 35 Filter 28, 36 Multiplier 29, 38 Limiter 31 Model magnetic flux controller 32 Model magnetic flux Estimator 33 Feedforward compensator

Claims (10)

Current detection means for detecting a primary current flowing through the induction motor; coordinate conversion means for converting and generating a torque current component and an excitation current component from the primary current; and a magnetic flux for estimating a magnetic flux of the induction motor from the excitation current component An estimation unit; a magnetic flux control unit that generates an excitation current command to reduce a deviation between a magnetic flux command input from the outside in the process of driving the induction motor and a magnetic flux estimated by the magnetic flux estimation unit; and the magnetic flux An excitation current limiting means for outputting an excitation current command within a limit value among excitation current commands output by the control means as an excitation current command necessary for control, and a motor control device for driving and controlling the induction motor by vector control ,
Magnetic flux delay compensation means for generating a magnetic flux delay correction command based on the magnetic flux command is provided, and the magnetic flux delay correction command is used to take a deviation from the magnetic flux estimated by the magnetic flux estimation means instead of the magnetic flux command. The motor control apparatus characterized by the above-mentioned. Current detection means for detecting a primary current flowing through the induction motor; coordinate conversion means for converting and generating a torque current component and an excitation current component from the primary current; and a magnetic flux for estimating a magnetic flux of the induction motor from the excitation current component An estimation unit; a magnetic flux control unit that generates an excitation current command to reduce a deviation between a magnetic flux command input from the outside in the process of driving the induction motor and a magnetic flux estimated by the magnetic flux estimation unit; and the magnetic flux An excitation current limiting means for outputting an excitation current command within a limit value among excitation current commands output by the control means as an excitation current command necessary for control, and a motor control device for driving and controlling the induction motor by vector control ,
Magnetic flux lag compensation means for generating a magnetic flux lag correction command based on the magnetic flux command is provided, and the magnetic flux lag correction command is added to the output of the magnetic flux control means and input to the excitation current limiting means. Motor control device. Current detection means for detecting a primary current flowing through the induction motor, coordinate conversion means for converting and generating a torque current component and an excitation current component from the primary current, and estimating a magnetic flux of the induction motor from the excitation current component Magnetic flux estimation means, magnetic flux control means for generating an excitation current command so as to reduce a deviation between a magnetic flux command input from the outside in the process of driving the induction motor and the magnetic flux estimated by the magnetic flux estimation means, A motor control device comprising: excitation current limiting means for outputting an excitation current command within a limit value among excitation current commands output by the magnetic flux control means as an excitation current command necessary for control; and driving control of the induction motor by vector control In
Magnetic flux delay compensation means for generating first and second magnetic flux delay correction commands based on the magnetic flux command, respectively, and of the first and second magnetic flux delay correction commands, the first magnetic flux delay correction command is It is used to take the deviation from the magnetic flux estimated by the magnetic flux estimating means instead of the magnetic flux command, and the second magnetic flux delay correction command is added to the output of the magnetic flux control means and input to the exciting current limiting means. The motor control apparatus characterized by the above-mentioned. The magnetic flux lag compensation means includes
A first filter that has a transfer characteristic that approximates the reciprocal of the transfer function of the magnetic flux estimator or a transfer characteristic that approximates the reciprocal of the transfer function of the magnetic flux estimator;
A second filter having a transfer characteristic that approximates the reciprocal of the transfer function of the magnetic flux control means or the reciprocal of the transfer function of the magnetic flux control means and that receives the output of the first filter;
A multiplier for multiplying the output of the second filter by a predetermined gain;
An adder for adding the output of the multiplier and the magnetic flux command;
The motor control device according to claim 1, further comprising: an output limiting unit that outputs, as the magnetic flux lag correction command, a value equal to or less than a limit value among the outputs of the adder. The output limiting means is
An output upper limit means for limiting the output to a set maximum value or less and an output lower limit means for limiting the output to a set minimum value or more with respect to the input signal, and when the magnetic flux command is input, the output 5. The magnetic flux lag correction command, which is an output of a limiting unit, is limited and output within a maximum value set in the output upper limit unit and a minimum value set in the output lower limit unit. The motor control apparatus described. The magnetic flux lag compensation means includes
A model magnetic flux control unit configured by an ideal model of the induction motor, and generating a model excitation current command based on a deviation between the magnetic flux command and the estimated model magnetic flux command;
A model magnetic flux estimating means configured by an ideal model of the induction motor and estimating the model magnetic flux command based on the model excitation current command;
The motor control device according to claim 3, wherein the model magnetic flux command is the first magnetic flux delay correction command, and the model excitation current command is the second magnetic flux delay correction command. The magnetic flux lag compensation means includes
Feedforward compensation means for calculating and generating a magnetic flux feedforward command based on the magnetic flux command;
A model magnetic flux control unit configured by an ideal model of a magnetic flux control system, and generating a model excitation current command based on a deviation between the magnetic flux feedforward command and the model magnetic flux command;
A model magnetic flux estimating means configured by an ideal model of the induction motor and estimating the model magnetic flux command based on the model excitation current command;
The motor control device according to claim 3, wherein the model magnetic flux command is the first magnetic flux delay correction command, and the model excitation current command is the second magnetic flux delay correction command. The model magnetic flux control means includes
The motor control device according to claim 6 or 7, wherein a response band constant for determining a response of the control system is set to a value larger than a response band constant of the magnetic flux control means. The feedforward compensation means includes
A first filter having a transfer characteristic approximating the inverse of the transfer function of the model magnetic flux estimating means or the inverse of the transfer function of the model magnetic flux estimating means and receiving the magnetic flux command;
A second filter having a transfer characteristic that approximates the reciprocal of the transfer function of the model magnetic flux control means or a transfer characteristic that approximates the reciprocal of the transfer function of the model magnetic flux control means;
A multiplier for multiplying the output of the second filter by a predetermined gain;
An adder for adding the output of the multiplier and the magnetic flux command;
The motor control device according to claim 7, further comprising: an output limiting unit that outputs, as the magnetic flux feedforward command, a value not more than a limit value among outputs of the adder. The output limiting means is
An output upper limit means for limiting the output to a set maximum value or less and an output lower limit means for limiting the output to a set minimum value or more with respect to the input signal, and when the magnetic flux command is input, the output The magnetic flux feedforward command, which is an output of a limiting unit, is limited and output within a maximum value set in the output upper limit unit and a minimum value set in the output lower limit unit. The motor control apparatus described.

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