JPH08107694A - Controller for synchronous motor - Google Patents

Abstract

PURPOSE: To smoothly start a synchronous motor without outputting a magnetic pole position signal from a rotor position detector. CONSTITUTION: A magnetic pole position estimator 23 estimates a magnetic pole position from an output torque ratio of a three-phase synchronous motor 1 after applying two currents to an armature having an arbitrary phase difference during start of a three-phase synchronous motor 1. In more detail, a magnetic pole position is estimated by using a speed difference ratio proportional to the torque ratio on behalf of the torque ratio, based on this, an armature current having a specific phase angle relative to an absolute position of the magnetic pole is applied thereby starting the three-phase synchronous motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor control device for supplying a current having a specific phase angle to the absolute position of magnetic poles of the synchronous motor.

[0002]

2. Description of the Related Art Conventionally, as a control device for a synchronous motor, for example, a three-phase synchronous motor, a rotor position detector for detecting the position of the rotor of the three-phase synchronous motor is provided, and from this rotor position detector, As shown in FIG. 8, a pulse consisting of a two-phase (A, B-phase) pulse train signal having a phase difference of 90 degrees and a zero marker (Z-phase) signal of one pulse per one rotation indicating the rotor absolute position. While outputting the encoder signal, a magnetic pole position signal composed of U, V and W phase signals having a phase difference of 120 degrees indicating the absolute position of the magnetic pole of the rotor is output.
At the time of starting the three-phase synchronous motor, the magnetic pole position signals U and V
And a rotor position detection signal is obtained from the W-phase signal, an armature current having a specific phase angle is caused to flow through the three-phase synchronous motor based on the signal, and thereafter, when the rotor position detector outputs a Z-phase signal, There is a configuration in which the position detection signal of the rotor is obtained from the A, B and Z phase signals which are pulse encoder signals, and based on this, the armature current is similarly controlled to flow through the three-phase synchronous motor.

In this configuration, the position detection signal obtained from the U, V and W phase signals, which are square waves with a phase difference of 120 degrees, is data with low resolution every 60 degrees, but the absolute position of the magnetic pole is always present. Therefore, it is most suitable at the time of starting, which indicates a low speed. However, since the resolution is low at the time of shifting to the normal operation indicating the high speed, it becomes impossible to perform high-precision control, and therefore, the resolution is high after the Z-phase signal indicating the rotor absolute position is output. The control is switched to the control based on the position detection signal by the A, B and Z phase signals.

[0004]

In the conventional structure as described above, the magnetic pole position signal composed of the U, V and W phase signals is used although the rotor position detector is used only at the time of starting. Since it is necessary to output, the configuration becomes complicated accordingly. In addition, since signal lines for U, V and W phase signals (three in the case of three phases) must be provided, there is a problem that reliability is lowered and the cost is increased as a whole.

The present invention has been made in view of the above circumstances, and an object thereof is to start a synchronous motor without causing a magnetic pole position signal to be generated only by generating a pulse encoder signal in a rotor position detector. It is an object of the present invention to provide a synchronous motor control device that can be smoothly operated.

[0006]

According to a first aspect of the present invention, there is provided a synchronous motor control device including a two-phase pulse train signal having a 90-degree phase difference obtained from a rotor position detector according to rotation of a rotor of the synchronous motor. Using a pulse encoder signal consisting of one pulse of zero marker signal for one rotation indicating the rotor absolute position,
When supplying a current having a specific phase angle with respect to the absolute position of the magnetic poles of the synchronous motor, when two armature currents having an arbitrary phase difference are passed through the synchronous motor at the time of starting the synchronous motor. The configuration is characterized in that the magnetic pole position estimating means for estimating the magnetic pole position from the output torque ratio of the synchronous motor is provided.

A control device for a synchronous motor according to claim 2 is
It is characterized by the configuration in which the current amplitudes of the two armature currents are set to be equal. A control device for a synchronous motor according to a third aspect is characterized in that the phase difference between two armature currents is set to 90 degrees. A control device for a synchronous motor according to a fourth aspect is characterized in that the magnetic pole position is estimated from a speed difference ratio proportional to the output torque ratio instead of the output torque ratio. A synchronous motor control device according to a fifth aspect of the present invention is characterized in that the control is switched to the control by the pulse encoder signal when the zero marker signal is output after the magnetic pole position is estimated.

[0008]

According to the synchronous motor control device of the present invention, the magnetic pole position estimating means estimates the magnetic pole position from the output torque ratio of the synchronous motor when two armature currents having an arbitrary phase difference are passed. Since this is performed, the synchronous motor can be smoothly started without obtaining the magnetic pole position signal from the rotor position detector.

According to the synchronous motor control device of the second aspect, the current amplitudes of the two armature currents flowing through the synchronous motor are set to be equal, so that the estimated magnetic pole position is ensured.

According to the synchronous motor control device of the third aspect, the phase difference between the two armature currents flowing in the synchronous motor is set to 90 degrees, which facilitates the calculation of the magnetic pole position estimation.

According to the synchronous motor control device of the fourth aspect, the speed difference ratio proportional to the output torque ratio is used for the magnetic pole position estimation instead of the output torque ratio. There is no need to do it.

According to the control device for a synchronous motor of the fifth aspect, when the zero marker signal is output after the magnetic pole position is estimated, the control is switched to the control by the pulse encoder signal. Switching to normal operation will be performed smoothly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a servo system will be described below with reference to FIGS. In FIG. 1 showing the overall configuration, a synchronous motor, for example, a three-phase input terminal of a three-phase synchronous motor 1 has an inverter circuit 5 formed by connecting transistors, which are switching elements, through three-phase bridges via feeder lines 2, 3 and 4. It is connected to the output terminal. Pulse encoder 6 as rotor position detector
Has a disc that rotates integrally with the rotor of the three-phase synchronous motor 1, and two-phase pulse train signals (A and B phase signals) and a zero marker signal (Z phase signal) according to the rotation of the disc. ) Is output (see FIG. 2).

The control device 7 is mainly composed of a microcomputer, and in FIG. 1, for the sake of convenience of explanation, main parts are shown in a functional block diagram. That is, the subtracter 8 receives the position command signal θrref at the positive (+) input terminal and the position detection signal θr obtained as described below at the negative (−) input terminal, and outputs the deviation signal from the output terminal. The deviation signal is output to the input terminal of the position controller 9. This position controller 9
Based on the deviation signal between the position command signal θrref and the position detection signal θr given from the subtracter 8, the speed command signal Vrref (indicating the angular velocity) is output from the output terminal. Various speed signals are shown with V as a subscript below. This is a substitute for the angular velocity ω), and the velocity command signal Vrref is given to the positive (+) input terminal of the subtractor 10. The subtractor 10 is adapted to be supplied with the speed detection signal Vr from the output terminal of the speed detector 11 at the negative (-) input terminal, and is a deviation signal between the speed command signal Vrref and the speed detection signal Vr. Is output from the output terminal, and this is applied to the input terminal of the speed controller 12.

The speed controller 12 outputs a current command signal Iref from an output terminal based on a deviation signal between the speed command signal Vrref and the speed detection signal Vr given from the subtractor 10. Signal Iref
Is applied to one input terminal of the function generator 13. The function generator 13 is provided with a current phase signal θ obtained as described later on the other input terminal, and a new function is generated from a predetermined function based on the current command signal Iref and the current phase signal θ. A current command signal is obtained, output from the output terminal and given to one input terminal of the current controller 14.

The current controller 14 is a current detector (current transformer) provided on the other three input terminals on the power supply lines 2, 3 and 4.
The U, V and W phase current detection signals of 15, 16 and 17 are given, and the D axis current command signal Ide is applied to the other two input terminals.
The rf and Q-axis current command signals Iqref are provided, an energization timing signal by PWM control is obtained based on the signals provided to these input terminals, and the energization timing signal is output from the output terminal to the inverter. It is designed to be applied to a transistor which is a switching element of the circuit 5.

The counter 18 receives the two pulse train signals (A and B phase signals) and the zero marker signal (Z phase signal) from the output terminals of the pulse encoder 6 at its three input terminals and counts them. The pulse count signal θro is output from the output terminal and applied to one positive (+) input terminal of the adder 19 and the input terminal of the data holder (latch). The data holder 20 has a pulse encoder 6 at its control terminal.
Z-phase signal from the
When the phase signal is given, the pulse count signal θro of the counter 18 at that time is latched and output from the output terminal as the pulse count latch signal θrz.

The pulse count latch signal θrz from the data holder 20 is applied to the input terminal of the sign inverter 21, which inverts the polarity of the input pulse count latch signal θrz. The pulse count latch inversion signal θt is output from the output terminal and is applied to the other positive (+) input terminal of the adder 19. The adder 19 receives the applied pulse count signal θro and the pulse count latch inversion signal θ
The position detection signal θr is obtained by adding t to the output terminal and is output from the output terminal to the negative (−) input terminal of the subtractor 8, the input terminal of the speed detector 11 and the b-side contact of the switching means 22. It is designed to give.

In this case, the speed detector 11 outputs the speed detection signal Vr based on the differentiation of the position detection signal θr. Further, the switching means 22 turns on the a-side contact when the three-phase synchronous motor 1 is started,
After the start-up, the b-side contact is switched to be turned on as described later, and when the b-side contact is turned on, the position detection signal θr becomes the current phase signal θ.

The magnetic pole position estimator 23, which is the magnetic pole position estimating means, outputs the shift angle signal θt1 instead of the conventional position detection signal based on the magnetic pole position signal, as will be described later. Is the switching means 22
It is designed to be applied to the a-side contact of the.

Next, the operation of this embodiment will be described with reference to FIGS. 2 to 6. First, the three-phase synchronous motor 1
The principle of magnetic pole position estimation will be described. To estimate the magnetic pole position, if the torque ratio generated by two armature currents having the same magnitude (current amplitude) but different directions (phase differences) is known, the relative angle between the current direction and the magnetic pole position can be obtained. It is the basic principle.

FIG. 3 shows current vectors I1 * and I2 * of two armature currents with the Dm axis as the magnetic pole direction. When the generated torque of these two current vectors I1 * and I2 * is obtained, the generated torque is proportional to the Qm axis component of the current vectors I1 * and I2 *, that is, the component orthogonal to the magnetic pole.

The torque T1 generated by the current vector I1 * whose direction differs from the Dm axis by α is represented by the equation (1). However, Tq is the generated torque (maximum torque) when the current vector is orthogonal to the magnetic pole.

[Equation 1]

Current vectors I1 * and β ° (β ° is arbitrary)
The torque T2 generated by the current vector I2 * whose directions are different from each other is expressed by the equation (2).

[Equation 2]

Therefore, from the expressions (1) and (2), the ratio of the generated torques T1 and T2 is as shown in the expression (3).

(Equation 3)

From the equation (3), the phase angle α between the current vector I1 * and the magnetic pole is given by the equation (4).

[Equation 4]

In this equation (4), the phase angle between the applied current vector I1 * and the magnetic pole can be obtained from the ratio of the torques T1 and T2 generated by the two current vectors I1 * and I2 * having the phase difference β. Is shown. Therefore, in order to obtain the magnetic pole position, the torques T1 and T2 generated when the current vectors I1 * and I2 * are respectively applied are measured by the torque detector to obtain the ratio T1 / T2.

However, it may take time and effort to measure the torque, and therefore the speed difference ratio is used here instead of the torque ratio. Now, for example, from t = 0 to t =
When the torque T is generated during t2, the speed at t = 0 is V0.

The velocity V1 at t = t1 is

(Equation 5) And the velocity at t = t2 is

(Equation 6) Is represented by

Therefore, when the speed difference ΔV between t1 and t1 (between Δt) is calculated,

(Equation 7) The relationship is established. Since the speed ratio between Δt is proportional to the torque, the speed difference ratio can be used instead of the torque ratio.

Next, based on the above principle, the specific procedure of the magnetic pole position estimation by the magnetic pole position estimator 23 will be described with reference to FIG.
This will be described with reference to the flowchart shown in FIG. When the magnetic pole position estimation routine is started by turning on the power of the servo system, first, “θt = 0
I1 is made to flow ”in step S1, and θt (shift angle signal) shown in FIG. 1 is set to θt = 0, and the current vector I1 * is made to flow to the Q-axis current command signal Iqref, and“ 3 m
s progress? The determination step S2 is performed. 3 ms in this determination step S2 is the time until the actual current follows the current command. Then, this determination step S2
If it is determined to be “YES”, the process proceeds to the process step S3 of “measuring velocity V1 (I1)” and the current vector I1 *
Measure the velocity V1 (I1) below. After that, "△
t has passed? To the determination step S4, where the predetermined time Δt has elapsed and the “speed V2 (I1) is measured.
ΔV (I1) = V2 (I1) −V1 (I1) is calculated ”, and the process proceeds to step S5.

In this processing step S5, the speed V2 (I1) under the current vector I1 * is measured, and the speed difference ΔV (I1) = V2 (I1) -V1 (I1) is calculated. Next, the process proceeds to the processing step S6 of "flow I2 with θt = β (β is arbitrary)", the shift angle signal θt is set to θt = β °, the current vector I2 * is passed to the Q-axis current command signal Iqref, and "3 ms After the determination step S7 of "Elapsed?", The process proceeds to the processing step S8 of "Measure the velocity V1 (I2)", and the velocity V under the current vector I2 *
1 (I2) is measured.

After that, a judgment step S of "Δt has elapsed?"
9 through “Measure speed V2 (I2) ΔV (I2) = V2
(I2) -V1 (I2) is calculated "processing step S10
To the speed V2 (I
2) is measured and the speed difference ΔV (I2) = V2 (I2) −V
Calculate 1 (I2). Furthermore, “speed ratio ΔV (I1) /
Calculate ΔV (I2) "processing step S11,
The speed difference ratio ΔV (I1) / ΔV (I2) is calculated. Then, the process proceeds to the process step S12 of "magnetic pole position estimation", and the phase angle (magnetic pole position) α is obtained from the equation (4) based on this speed difference ratio ΔV (I1) / ΔV (I2).

In the above description, the current vectors I1 *, I
2 * is obtained with θt = 0 and θt = β °, the details of which will be described in more detail. FIG. 4 shows three coordinate axes related to the magnetic pole position estimation. That is, D
m and Qm axes are orthogonal axes representing magnetic poles, Dr and Qr axes are A,
It is an orthogonal axis that represents the pulse count value (signal) θro of the B-phase signal. In this case, since the pulse count value θro is cleared when the power of the support system is turned on,
The relative angle θrz between the Dr, Qr axes and the Dm, Qm axes depends on the magnetic pole position when the power is turned on. Furthermore, Dref, Qref
Assuming that the axis is a quadrature axis that represents the reference phase θ of the current control, the Dref and Qref axes and the Dr and Qr axes have different phase angles by θt. Here, θt can be set to an arbitrary value by the CPU in the control device 7. As described above, it is possible to realize the current vector I1 * with θt = 0 and the current vector I2 * with θt = β °.

On the other hand, when the magnetic pole position estimator 23 finally obtains the magnetic pole position α based on the equation (4) in the processing step S12, it finally shifts the current vector in the Qm-axis direction. Set "processing step S1
Then, the shift angle signal θt1 is set.

This shift angle (signal) θt1 is given by the following (8)
It is represented by a formula.

(Equation 8)

Thus, the shift angle signal θt1 is given from the magnetic pole position estimator 23 to the a-side contact of the switching means 22. When the servo system is powered on, that is, when the three-phase synchronous motor 1 is started, the a-side contact of the switching means 22 is turned on, so the shift angle signal θt1 is given to the function generator 13 as the current phase signal θ. Will be available. As a result, the shift angle signal θt1 is applied to the three-phase synchronous motor 1.
Based on the above, an armature current having a specific phase angle with respect to the absolute position of the magnetic pole is supplied via the function generator 13, the current controller 14 and the inverter circuit 5, and the three-phase synchronous motor 1 is started.

When the three-phase synchronous motor 1 is started, the pulse encoder 6 shows the A and B phase signals which are two-phase pulse train signals having a phase difference of 90 degrees and the absolute rotor position, as shown in FIG. A pulse encoder signal consisting of a Z-phase signal, which is a zero marker signal of one pulse per one rotation, is outputted, and these are given to the counter 18. Then, the pulse count signal θro from the counter 18 is given to the adder 19 and output as the position detection signal θr.
After that, when the pulse encoder 6 outputs the Z-phase signal and this is given to the control terminal of the data holder 20, the data holder 20 latches the pulse count signal θro of the counter 18 at that time and outputs the pulse count latch signal. θ
The pulse count latch signal θrz is output as rz, and the polarity of the pulse count latch signal θrz is inverted by the sign inverter 21, and the pulse count latch inverted signal θt is supplied to the adder 19. As a result, the position detection signal θr from the adder 19
Is cleared, and thereafter, the position detection signal θr comes to indicate the correct magnetic pole position of the three-phase synchronous motor 1.

When the pulse encoder 6 outputs the Z-phase signal, the switching means 22 is switched so as to turn on the b-side contact at this time. Therefore, after that, the position indicating the correct magnetic pole position is obtained. The detection signal θr is given to the function generator 13 as the current phase signal θ, and the three-phase synchronous motor 1 accelerates the load to the position commanded by the position command signal θrref under the control of the controller 7. , Drive at constant speed and deceleration.

As described above, according to this embodiment, the control device 7
The magnetic pole position estimator 23 of No. 2 outputs the three-phase synchronous motor 1 when the three-phase synchronous motor 1 is started, when the current vectors I1 * and I2 *, which are two armature currents having an arbitrary phase difference, are applied. The magnetic pole position is estimated from the torque ratio T1 / T2 and is used as a substitute for the conventional magnetic pole position signal.

Therefore, unlike the prior art, the three-phase synchronous motor 1 can be smoothly started without outputting the magnetic pole position signal from the pulse encoder 6 which is the rotor position detector, and the configuration of the pulse encoder 6 is configured. It can be simplified, and the signal line for the magnetic pole position detection signal is not needed,
The reliability is improved, and the cost can be reduced as a whole.

Further, in obtaining the torque ratio of the three-phase synchronous motor 1, since the current amplitudes of the two current vectors I1 * and I2 * are made equal, accurate measurement is possible and the magnetic poles are accurately measured. Position estimation can be performed.
Further, in the actual magnetic pole position estimation, the speed difference ratio proportional to the torque ratio is used instead of the torque ratio, so that it is not necessary to perform difficult torque measurement.

FIG. 7 is a view corresponding to FIG. 3 showing a second embodiment of the present invention. That is, in the first embodiment, the phase difference β between the current vectors I1 * and I2 *, which are two armature currents, was set arbitrarily, but in the second embodiment, this phase difference β is set. β is set to 90 degrees.

The torque T2 generated by the current vector I2 * at this time is given by the equation (9) by substituting β = 90 ° into the equation (2).

[Equation 9]

Similarly, the torque ratio is as follows from the equation (3).

[Equation 10]

As a result, the phase difference α between the current vector I1 * and the magnetic pole can be obtained as follows.

[Equation 11]

Therefore, according to the second embodiment, the same operation and effect as those of the first embodiment can be obtained. In particular, in the second embodiment, two armature currents, ie, current vectors I1 * and By setting the phase difference β of I2 * to 90 degrees, the equation (4) can be simplified as the equation (11), and the calculation of the magnetic pole position estimation becomes easy.

The above embodiment has been described with respect to the case where the present invention is applied to the three-phase synchronous motor of the servo system, but the present invention is not limited to this, and can be applied to all control devices of the synchronous motor. In addition, the present invention is not limited to the embodiments described above and shown in the drawings, and it is needless to say that the present invention can be appropriately modified and implemented without departing from the scope of the invention.

[0049]

Since the present invention is as described above, it has the following effects. According to the synchronous motor control device of the first aspect, the magnetic pole position is estimated from the output torque ratio of the synchronous motor when two armature currents having an arbitrary phase difference are passed. The synchronous motor can be smoothly started without obtaining the magnetic pole position signal from the detector. Therefore, the structure of the rotor position detector can be simplified and the reliability can be improved. Can be

According to the synchronous motor control device of the second aspect, the current amplitudes of the two armature currents supplied to the synchronous motor are set to be equal, so that the estimated magnetic pole position can be ensured. Become.

According to the synchronous motor controller of the third aspect of the invention, the phase difference between the two armature currents flowing in the synchronous motor is set to 90 degrees, which facilitates the calculation of the magnetic pole position estimation. .

According to the synchronous motor controller of the fourth aspect, the speed difference ratio proportional to the output torque ratio is used for the magnetic pole position estimation instead of the output torque ratio, so that difficult torque measurement is performed. There is no need to do it.

According to the synchronous motor control device of the fifth aspect, when the zero marker signal is output after the magnetic pole position is estimated, the control is switched to the control by the pulse encoder signal. Switching to operation is performed smoothly.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a first embodiment of the present invention.

FIG. 2 is a waveform diagram of a pulse encoder signal.

FIG. 3 is a diagram showing two vector currents.

FIG. 4 is a diagram showing three orthogonal axes.

FIG. 5: Flow chart

FIG. 6 Time chart

FIG. 7 is a view corresponding to FIG. 3 showing a second embodiment of the present invention.

FIG. 8 is a waveform diagram of a conventional pulse encoder signal.

[Explanation of symbols]

1 is a three-phase synchronous motor (synchronous motor), 5 is an inverter circuit, 6 is a pulse encoder (rotor position detector), 7 is a control device, and 23 is a magnetic pole position estimator (magnetic pole position estimating means).
Indicates.

Claims (5)

[Claims] 1. A two-phase pulse train signal having a 90-degree phase difference obtained from a rotor position detector according to the rotation of a rotor of a synchronous motor, and a zero marker signal having one pulse per one rotation indicating an absolute position of the rotor. In the controller of the synchronous motor, which supplies a current having a specific phase angle with respect to the absolute position of the magnetic poles of the synchronous motor by using the pulse encoder signal, A synchronous motor control device comprising magnetic pole position estimating means for estimating a magnetic pole position from an output torque ratio of the synchronous motor when two armature currents having a phase difference are passed. 2. The control device for a synchronous motor according to claim 1, wherein the current amplitudes of the two armature currents are set to be equal to each other. 3. The control device for a synchronous motor according to claim 1, wherein the phase difference between the two armature currents is set to 90 degrees. 4. The control device for a synchronous motor according to claim 1, wherein the magnetic pole position is estimated from a speed difference ratio proportional to the output torque ratio instead of the output torque ratio. 5. The control device for the synchronous motor according to claim 1, wherein when the zero marker signal is output after the magnetic pole position is estimated, the control is switched to the control by the pulse encoder signal.