JP2006042444A - Motor control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control unit for avoiding a situation of incontrollability of a motor due to an error in a leading phase calculation, and regularly and efficiently driving the motor. <P>SOLUTION: In a control system for varying the leading phase θ from a rotor rotation phase θm of the IPM motor 13 so as to maximize the total torque, including a magnet torque and a reluctance torque of the IPM motor 13, a limiter 30 is provided at the output of an optimal leading phase calculating section 29, and limits the optimal leading phase ΔθTmax within a regulated range of 0-45°. Since the limiter 30 limits an inappropriate value due to errors in the leading phase calculation within the regulated range, the situation of the incontrollability of the motor is avoided; and the IPM motor 13 can be driven efficiently at all times. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor control device used, for example, for driving an electric motor of an elevator, and more particularly to a motor control device that performs drive control of an IPM motor in which a permanent magnet is embedded in a rotor.

  For example, as a motor used for driving an electric motor of an elevator, an SPM (Surface Permanent Magnet) motor in which a permanent magnet is stuck inside a rotor (rotor) is generally used. However, in this SPM motor, it is necessary to put a stainless steel tube around the rotor so that the permanent magnets are not scattered by centrifugal force during high-speed rotation, and the iron loss at this portion reduces the efficiency.

  Therefore, an IPM (Internal Permanent Magnet) motor that prevents permanent magnets from being scattered by embedding the permanent magnets inside the rotor is becoming mainstream. In this IPM motor, since reluctance torque resulting from the saliency of the rotor can be used in addition to the magnet torque generated by the permanent magnet, there is an advantage that a large torque can be efficiently obtained even in a small size.

In such a motor control device that controls an IPM motor, control is performed to optimize the leading phase of the winding current so that the total torque of the magnet torque and reluctance torque of the IPM motor is always maximized. (For example, refer to Patent Document 1).
JP-A-10-94285

  As described above, in the control of the IPM motor, the advance phase is optimized so that the total torque including the magnet torque and the reluctance torque is always maximized.

  However, an inappropriate value may be calculated as the lead phase due to, for example, an erroneous calculation by the microcomputer. If an inappropriate value is calculated as the advance phase, not only the driving efficiency of the motor is lowered, but also depending on the value, there is a problem that the motor is out of control due to step-out. In such a case, especially in the field of elevators, the drive of the motor directly affects the safety of passengers in the car, so it is absolutely necessary to avoid situations where motor control becomes impossible. It becomes.

  The present invention has been made in view of the above points, and provides a motor control device that can always efficiently drive a motor while avoiding a situation in which motor control becomes impossible due to erroneous calculation of the lead phase. The purpose is to do.

  A motor control apparatus according to the present invention includes a motor having a saliency in which a permanent magnet is embedded in a rotor and a q-axis inductance that is an orthogonal axis is larger than an inductance of a d-axis that is a direct axis of the permanent magnet. The phase detection means for detecting the rotational phase of the rotor in the above, and the total torque obtained by adding the reluctance torque generated by the inductance change of the d-axis and the q-axis to the magnet torque by the permanent magnet is maximized. A lead phase calculating means for calculating a lead phase from the rotational phase of the rotor detected by the phase detecting means; a limiter means for limiting the lead phase calculated by the lead phase calculating means so as not to exceed a prescribed range; The drive of the motor is controlled based on the advance phase limited within the specified range by the limiter means. Constituted by and a that drive control means.

  According to such a configuration, the advance phase is calculated so that the total torque obtained by combining the magnet torque and the reluctance torque of the motor is maximized, and the drive of the motor is controlled based on the advance phase. At this time, if an inappropriate advance phase is calculated due to an erroneous calculation, the value of the advance phase is limited within the specified range by the limiter means, so that it is always efficient to avoid the situation where motor control becomes impossible. The motor can be driven.

  Further, the motor control device of the present invention includes a motor having a saliency in which a permanent magnet is embedded in the rotor, and the q-axis inductance that is the orthogonal axis is larger than the d-axis inductance that is the direct axis of the permanent magnet, Phase detection means for detecting the rotational phase of the rotor in the motor, and the total torque obtained by adding the reluctance torque generated by the inductance change of the d-axis and q-axis to the magnet torque by the permanent magnet is maximized. A lead phase calculating means for calculating a lead phase from the rotational phase of the rotor detected by the phase detecting means; and a d-axis for outputting a d-axis current command corresponding to the lead phase calculated by the lead phase calculating means. Limit the current command means and the value of the d-axis current command output from the d-axis current command means so as not to exceed the specified range. And limiter means constituted by and a drive control means for controlling driving of the motor based on the d-axis current command that is limited within the above specified range by the limiter unit.

  According to such a configuration, the advance phase is calculated so that the total torque including the magnet torque and the reluctance torque of the motor is maximized, and the drive of the motor is controlled based on the d-axis current command according to the advance phase. Is done. At this time, if an inappropriate advance phase is calculated due to an erroneous calculation or the like, the value of the d-axis current command corresponding to the advance phase is limited within a specified range by the limiter means, and the motor control becomes impossible. Thus, the motor can always be driven efficiently.

  According to the present invention, in the control method for varying the advance phase so that the total torque obtained by combining the magnet torque and the reluctance torque of the motor is maximized, a limiter is provided for limiting the advance phase value within a specified range. Thus, it is possible to avoid a situation in which motor control becomes impossible when an inappropriate advance phase is calculated due to erroneous calculation or the like, and the motor can always be efficiently driven with the advance phase within a specified range.

  In addition, even in a control method that fluctuates the value of the d-axis current command corresponding to the advance phase, by providing a limiter for limiting the value of the d-axis current command within a specified range, The situation where the control becomes impossible can be avoided, and the motor can always be driven efficiently.

  First, before describing an embodiment of the present invention, the torque characteristics of an IPM motor that is a control target of the present invention will be described in comparison with an SPM motor.

  As shown in FIG. 3, the SPM motor is composed of a rotor (rotor) 1, a permanent magnet 2 attached inside the rotor 1, and a winding (coil) 3 disposed around the rotor 1. The In this SPM motor, a magnet torque is generated by the permanent magnet 2. As shown in FIG. 4, the magnet torque of the SPM motor becomes maximum when the winding current advance phase θ (advance angle with respect to the rotation phase of the rotor 1) is 0 degrees, and fluctuates in the range of 90 degrees before and after that. .

  On the other hand, the IPM motor is a permanent magnet embedded type motor. As shown in FIG. 5, the rotor (rotor) 4, the permanent magnet 5 embedded in the rotor 4, and the rotor 4 are arranged around the rotor 4. It is composed of windings (coils) 6 arranged. In this IPM motor, reluctance torque due to the saliency of the rotor 4 is generated in addition to the magnet torque generated by the permanent magnet 5.

  That is, in the IPM motor, a difference occurs between the inductance Ld of the d-axis (the direct axis of the permanent magnet 5) of the magnetic circuit by the winding 6 and the inductance Lq of the q-axis (the orthogonal axis of the permanent magnet 5), and the difference is the reluctance. Generated as torque. Therefore, as shown in FIG. 6, in the IPM motor, a total torque obtained by combining the magnet torque by the permanent magnet 5 and the reluctance torque generated by the inductance change of the d-axis and the q-axis can be obtained.

  In FIG. 6, the dotted line in the figure represents the characteristics of the magnet torque, which is maximum when the leading phase θ of the winding current is 0 degrees, and fluctuates in the range of 90 degrees before and after that. Also, the alternate long and short dash line in the figure represents the characteristic of the reluctance torque, which is maximum when the leading phase θ of the winding current is 45 degrees, and fluctuates in the range of 45 degrees before and after that. Therefore, the maximum value of the total torque including these torques is larger than the maximum torque of the SPM motor by ΔT.

  Here, when the torque of the IPM motor is T, it is generally expressed by the following equation (1).

T = Φ · Iq− (Ld−Lq) · Id · Iq (1)
Φ: Armature flux linkage by permanent magnet Id: d-axis component of armature winding current Iq: q-axis component of armature winding current
Ld: d-axis inductance Lq: q-axis inductance In the above equation (1), Φ · Iq of one item is the magnitude of the magnet torque (that is, the torque of the SPM motor), and (Ld−Lq) · Id of the two items Iq is the reluctance torque. In this case, since Ld <Lq, it is calculated as a negative value in the equation. Actually, the number of pole pairs Pn is multiplied by the expressions of the first item and the second item.

  Further, the relationship between the winding current I and the advance phase θ on the dq coordinate axis is as shown in FIG. In FIG. 7, the d-axis is the vector direction of the armature flux linkage Φ, and the q-axis is the vector direction of the induced electromotive force E0.

  Here, as shown in FIG. 8, the value of the lead phase (referred to as the optimum lead phase ΔθTmax) at which the total torque becomes the maximum value changes depending on the ratio of the magnitude of the magnet torque and the reluctance torque of the IPM motor. The range that the optimum advance phase ΔθTmax can take is always between 0 degrees and 45 degrees (0 to π / 4). Therefore, the present invention is characterized in that the advance phase is always varied within the specified range using a limiter that defines the range of 0 to 45 degrees as the specified range of the optimum advance phase θTmax.

  Hereinafter, embodiments of the present invention will be described.

(First embodiment)
FIG. 1 is a block diagram showing a functional configuration of the motor control device according to the first embodiment of the present invention. This motor control device is used for, for example, an elevator, and is realized by a control device 11 including a microcomputer in a portion surrounded by an alternate long and short dash line in the drawing. The control device 11 generates U-phase, V-phase, and W-phase voltage signals VuC, VvC, and VwC and applies them to the inverter 12.

  The inverter 12 performs three-phase excitation switching of the IPM motor 13 based on these voltage signals VuC, VvC, and VwC, and drives the IPM motor 13 to rotate.

  The IPM motor 13 is a motor to be controlled by the present invention. As described above, the permanent magnet is embedded in the rotor, and the d-axis inductance Ld, which is the direct axis of the permanent magnet, is q. It has a saliency greater than the shaft inductance Lq. A reluctance torque is generated by the difference between the d-axis inductance Ld and the q-axis inductance Lq (Ld <Lq), and a total torque obtained by adding a magnet torque by a permanent magnet is obtained.

  Further, a current detector 14 is provided for each of the U, V, and W phases between the inverter 12 and the IPM motor 13. The current detector 14 detects each current value of each phase supplied to the IPM motor 13 and feeds it back to the control device 11. In addition, if it is the structure which performs 2 phase PWM control with respect to the IPM motor 13, it can respond also by detecting the electric current of 2 phases of U phase and W phase as shown with a dotted line.

  The IPM motor 13 is provided with a phase detector 15. The phase detector 15 is made of, for example, a resolver, detects the rotational phase θm of the rotor in the IPM motor 13 (this may be referred to as a magnetic pole phase), and feeds it back to the control device 11.

  The control device 11 performs control to optimize the advance phase θ from the rotational phase θm of the rotor so that the total torque (magnet torque + reluctance torque) is always maximized. When this control device 11 is shown functionally, a speed control unit (ASR) 21, a d-axis current control unit (ACR) 22, a q-axis current control unit 23, and a dq / UVW conversion unit 24 , A PWM control unit 25, a UVW / dq conversion unit 26, a phase / speed conversion unit 27, a current calculation unit 28, an optimum advance phase calculation unit 29, and a advance phase control limiter 30. In the figure, 31 to 33 are subtracters, and 34 is an adder.

  In such a configuration, a difference signal between the target speed signal FR0 of the IPM motor 13 and the actual speed signal FR is given to the speed control unit 21 via the subtractor 31. The actual speed signal FR is obtained by differentiating the rotational phase θm of the rotor of the IPM motor 13 detected by the phase detector 15 by the phase / speed converter 27.

  The speed control unit 21 generates a q-axis current signal IqC based on a difference signal between the target speed signal FR0 and the actual speed signal FR. The q-axis current signal IqC is compared with the q-axis current signal IqF indicating the feedback current value obtained from the UVW / dq converter 26 by the subtractor 33, and the difference signal is given to the q-axis current controller 23. Based on the difference signal between the q-axis current signal IqC and the q-axis current signal IqF, the q-axis current control unit 23 generates a q-axis voltage signal VqC that sets the current difference to zero.

  On the other hand, with respect to the d-axis current, first, the d-axis current signal IdC = 0 is compared with the d-axis current signal IdF indicating the feedback current value obtained from the UVW / dq converter 26 by the subtractor 32, and the difference signal is obtained. Is supplied to the d-axis current control unit 22. Based on the difference signal between the d-axis current signal IdC (= 0) and the d-axis current signal IdF, the d-axis current control unit 22 generates a d-axis voltage signal VdC whose current difference is zero.

  The dq / UVW conversion unit 24 generates the three-phase voltage signals EuC, EvC, and EwC of the U-phase, V-phase, and W-phase of the IPM motor 13 from the d-axis voltage signal VdC and the q-axis voltage signal VqC to generate a PWM control unit. To 25. The PWM control unit 25 performs PWM (Pulse Width Modulation) control based on these voltage signals EuC, EvC, and EwC, and generates signals VuC, VvC, and VwC that are pulse width modulated at a predetermined frequency. The inverter 12 excites each phase while switching each phase of the IPM motor 13 at a predetermined timing based on the pulse-width-modulated signals VuC, VvC, and VwC.

  As a PWM control method at this time, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-149660, etc., switching of one of the three phases is suspended and PWM control is performed with the remaining two phases. There are two-phase modulation.

  The IPM motor 13 is rotationally driven by the output signal of the inverter 12. At this time, the current value currently supplied to each phase is detected by the current detector 14, and the current signals IuF, IvF, IwF are sent to the control device 11. In addition to the feedback, the current rotational phase θm (rotor rotational angle) of the IPM motor 13 is detected by the phase detector 15 and fed back to the control device 11.

  The current signals IuF, IvF, and IwF are converted into d-axis and q-axis current signals IdF and IqF based on the current control phase signal θi by the UVW / dq converter 26, and are supplied to the subtracters 32 and 33, respectively. . Further, the rotational phase θm is given to the phase / velocity conversion unit 27 to be converted into a velocity signal FR and also to the phase control adder 34.

  Here, the control device 11 performs the process of optimizing the lead phase θ of the winding current I shown in FIG. 7 so that the total torque obtained by combining the magnet torque and the reluctance torque of the IPM motor 13 is always maximized. . The portion that performs the optimization process of the advance phase θ is the optimum advance phase calculation unit 29.

  The optimum lead phase calculation unit 29 is based on the magnitude of the winding current I calculated by the current calculation unit 28, and the optimum lead phase ΔθTmax at which the total torque including the magnet torque and the reluctance torque of the IPM motor 13 is always maximized. Is calculated. In addition, as a method of obtaining the optimum advance phase ΔθTmax, for example, there are a method of obtaining with reference to a table in which the winding current I and the optimum advance phase ΔθTmax are previously associated, a method of obtaining according to a predetermined calculation formula, and the like. The invention is not particularly limited to these methods. The sign of the optimum advance phase ΔθTmax is assumed to be the q-axis current signal IqC that is the output of the speed control unit 21 as a torque command Tm and synchronized with the sign of the torque command Tm.

  Here, when the optimum advance phase ΔθTmax is calculated by the optimum advance phase calculation unit 29, whether or not the value of the optimum advance phase ΔθTmax is within the specified range of 0 degrees to 45 degrees shown in FIG. Is determined.

  As a result, if the value of the optimum advance phase ΔθTmax is within the specified range, it is output as an effective value to the adder 34 as it is. On the other hand, when the value of the optimum advance phase ΔθTmax exceeds the specified range, the limiter 30 limits the value within the specified range and outputs it to the adder 34.

  Specifically, for example, when the value of the optimum advance phase ΔθTmax is calculated to be 50 degrees, the value is limited to 45 degrees within the restriction range and output. For example, when it is calculated as a negative value such as −10 degrees, the output is limited to 0 degrees closest to the regulation range.

  The adder 34 adds the rotational phase θm of the IPM motor 13 and the optimum advance phase ΔθTmax to obtain the current control phase θi, which is supplied to the dq / UVW conversion unit 24 and the UVW / dq conversion unit 26. As a result, the lead phase θ of the winding current I is controlled based on the current control phase θi, and the IPM motor 13 is rotationally driven so as to always obtain the maximum total torque.

  As described above, in the control method in which the advance phase θ is varied so that the total torque obtained by combining the magnet torque and the reluctance torque of the IPM motor 13 is always maximized, the value of the optimum advance phase ΔθTmax is specified within a specified range of 0 to 45 degrees. By providing the limiter 30 that restricts the motor, it is possible to avoid a situation in which the motor cannot be controlled when an inappropriate value is calculated by, for example, erroneous calculation. Further, it is possible to avoid a decrease in the total torque output due to the negative advance phase θ, and it is possible to efficiently drive the IPM motor 13 using the optimum advance phase ΔθTmax that is always within the specified range.

(Second Embodiment)
In the first embodiment, the control method for changing the leading phase θ of the winding current I so as to maximize the total torque of the IPM motor 13 has been described. However, instead of the leading phase θ, the d-axis current signal IdC is used. The same effect can be obtained by providing a d-axis current control limiter corresponding to 0 to 45 degrees of the advance phase θ for the control method for varying the phase.

  A specific example is shown in FIG. FIG. 2 is a block diagram showing a functional configuration of the motor control device according to the second embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  In FIG. 2, the control device 40 that controls the rotational drive of the IPM motor 13 is composed of a microcomputer, and as in the first embodiment, a speed control unit 21, a d-axis current control unit 22, and a q-axis current control unit. 23, a dq / UVW converter 24, a PWM controller 25, a UVW / dq converter 26, a phase / velocity converter 27, a current calculator 28, an optimum advance phase calculator 29, and the like. In addition, 31-33 in a figure is a subtractor.

  Here, in the second embodiment, the control device 40 includes a d-axis current command unit 41 and a d-axis current control limiter 42.

  The d-axis current command unit 41 determines a d-axis current value corresponding to the optimum advance phase ΔθTmax obtained by the optimum advance phase calculation unit 29 described above, and outputs a current signal IdC indicating the d-axis current value. The limiter 42 applies a restriction corresponding to 0 to 45 degrees of the advance phase θ on the d-axis current signal IdC output from the d-axis current command unit 41.

  According to such a configuration, when the optimum advance phase ΔθTmax that always maximizes the total torque of the IPM motor 13 is calculated by the optimum advance phase calculation unit 29, the d-axis current command unit 41 sets the optimum advance phase ΔθTmax to the optimum advance phase ΔθTmax. In addition, a d-axis current signal IdC is output in order to change the d-axis current. At this time, in the limiter 42 provided on the output side of the d-axis current command unit 41, the d-axis current signal IdC output at that time corresponds to a d-axis current corresponding to 0 to 45 degrees of the advance phase θ. It is determined whether it is within the prescribed range.

  As a result, if the value of the d-axis current signal IdC is within the specified range, the value is output as it is to the subtractor 32 as an effective value. On the other hand, if the value of the d-axis current signal IdC exceeds the specified range, the limiter 42 limits the value to the specified range and outputs the result to the subtractor 32. The subsequent processing is the same as in the first embodiment, and the IPM motor 13 is PWM-controlled while comparing the d-axis and q-axis feed currents from the IPM motor 13.

  As described above, even if the d-axis current signal IdC is varied based on the optimum advance phase ΔθTmax, if the d-axis current control limiter 42 corresponding to 0 to 45 degrees is provided, Similarly, it is possible to avoid a situation in which the motor cannot be controlled, and the IPM motor 13 can always be driven efficiently.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the function structure of the motor control apparatus in the 1st Embodiment of this invention. The block diagram which shows the function structure of the motor control apparatus in the 2nd Embodiment of this invention. The figure for demonstrating the rotor structure of a SPM motor. The figure which shows the torque characteristic of a SPM motor. The figure for demonstrating the rotor structure of an IPM motor. The figure which shows the torque characteristic of an IPM motor. The figure which shows the relationship between the winding current in an IPM motor, and a lead phase. The figure which shows the relationship between the magnitude | size of the magnet torque and reluctance torque in an IPM motor, and the optimal advance phase.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Control apparatus, 12 ... Inverter, 13 ... IPM motor, 14 ... Current detector, 15 ... Phase detector, 21 ... Speed control part (ASR), 22 ... d-axis current control part (ACR), 23 ... q axis Current controller (ACR), 24 ... dq / UVW converter, 25 ... PWM controller, 26 ... UVW / dq converter, 27 ... phase / velocity converter (S), 28 ... current calculator, 29 ... optimal advance Phase calculation unit, 30 ... advance phase control limiter, 31 to 33 ... subtractor, 34 ... adder, 40 ... control device, 41 ... d-axis current command unit, 42 ... d-axis current control limiter.

Claims (4)

A motor having a saliency in which a permanent magnet is embedded in the rotor and the inductance of the q-axis that is the orthogonal axis is larger than the inductance of the d-axis that is the direct axis of the permanent magnet;
Phase detection means for detecting the rotational phase of the rotor in the motor;
From the rotational phase of the rotor detected by the phase detecting means, the total torque obtained by adding the reluctance torque generated along with the inductance change of the d-axis and the q-axis to the magnet torque by the permanent magnet is maximized. A lead phase calculating means for calculating a lead phase;
Limiter means for limiting the advance phase calculated by the advance phase calculation means so as not to exceed the specified range;
A motor control device comprising: drive control means for controlling drive of the motor based on a lead phase limited within the specified range by the limiter means.   2. The motor control device according to claim 1, wherein the prescribed range by the limiter means is set to 0 to 45 degrees of the lead phase. A motor having a saliency in which a permanent magnet is embedded in the rotor and the inductance of the q-axis that is the orthogonal axis is larger than the inductance of the d-axis that is the direct axis of the permanent magnet;
Phase detection means for detecting the rotational phase of the rotor in the motor;
From the rotational phase of the rotor detected by the phase detecting means, the total torque obtained by adding the reluctance torque generated along with the inductance change of the d-axis and the q-axis to the magnet torque by the permanent magnet is maximized. A lead phase calculating means for calculating a lead phase;
D-axis current command means for outputting a d-axis current command corresponding to the lead phase calculated by the lead phase calculation means;
Limiter means for limiting the value of the d-axis current command output from the d-axis current command means so as not to exceed a specified range;
A motor control device comprising: drive control means for controlling drive of the motor based on a d-axis current command restricted within the specified range by the limiter means.   4. The motor control apparatus according to claim 3, wherein the prescribed range by the limiter means is set in correspondence with a lead phase of 0 degrees to 45 degrees.

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