JP5481860B2 - Motor control device - Google Patents

Description

The present invention relates to a motor control device capable of reliably and easily reducing vibration of one pulse at a stop.

The motor is controlled by the motor control device so that the position detection value coincides with the position command, and there is a general technical problem that the motor vibrates with ± 1 pulse of the position detection value in the stopped state.
In order to solve this general technical problem, the conventional motor control device generates vibration at the time of stop by providing a dead zone in the torque command so as to cancel the fluctuation of the torque command corresponding to ± 1 pulse in the motor stop state. It was reduced (see, for example, Patent Document 1).
Also, the speed is calculated from the two-phase analog signal of the position detector and transmitted to the control device, and the position between ± 1 pulse is interpolated between the pulses of the position detection value using the speed calculation value in the control device. Some have reduced the vibration at the time of stop by obtaining (see, for example, Patent Document 2).

FIG. 8 is a diagram showing a configuration of a conventional first motor control device. In the figure, 81 is a motor, 82 is an encoder, 83 is a speed detection circuit, 84 is a position deviation calculation circuit, 85 is a speed deviation calculation circuit, 86 is a torque command generation circuit, 87 is a motor stop determination circuit, and 88 is a dead zone forming circuit. Represents.
The speed detection circuit 83 calculates the current speed from the current position information from the encoder 82. The position deviation calculation circuit 84 calculates a position deviation from the position command data from the upper level and the current position data from the encoder 82. The speed deviation calculation circuit 85 calculates a speed deviation from the position deviation and the current speed. The torque command generation circuit 86 outputs a torque command based on the speed deviation. The motor stop determination circuit 87 outputs a motor stop determination signal from the position command and the position deviation. The dead zone forming circuit 88 adjusts and outputs a torque command from the motor stop determination signal.

When the motor reaches the vicinity of the positioning point, the position command becomes 0 and the position deviation gradually converges to 0. The motor stop determination circuit 87 determines that the motor is stopped when the position command is 0 and the position deviation is within ± 1 pulse, and outputs a motor stop determination signal to the dead zone forming circuit 88.
The dead zone forming circuit 88 observes the fluctuation of the torque command of the torque command generation circuit 86 and outputs the torque command from the torque command generation circuit 86 to the motor as it is in the motor rotation state, but ± 1 of the encoder in the motor stop state. The torque command is adjusted and output to the motor so as to cancel the torque command change of the torque command generation circuit 86 with respect to the pulse fluctuation.

Therefore, a dead zone is formed in which the torque command is constant when the position command is 0, the position deviation is near 0, and the motor is within the positioning point ± 1 pulse, and the motor slightly vibrates against ± 1 pulse fluctuation of the encoder. Can be suppressed.
As described above, the conventional first motor control device suppresses the slight vibration of the motor with respect to the ± 1 pulse fluctuation of the encoder by providing the dead zone of the torque command with respect to the ± 1 pulse fluctuation of the encoder in the motor stopped state. .

FIG. 9 is a diagram showing a configuration of a conventional second motor control device. In the figure, 91 is a control device, 92 is a detector, 93 is a servo motor, 94 is a position detector, 95 is a square wave generator, 96 is a counter, 97 is a velocity signal generator, and 98 is a position signal corrector. .
In FIG. 9, the principle of the speed signal generator will be described. The first analog signal is Va, and the second analog signal is Vb. Here, as shown in Expression (1), the square root of the sum of the square of Va and the square of Vb is calculated.
√ ((dVa / dt) ^ 2 + (dVb / dt) ^ 2) (1)
Va = a · sin (2πx / l), Vb = a · cos (2πx / l)
Here, a is the voltage amplitude value of the analog signal, x is the position or angle, l is the period of the analog signal,
(DVa / dt) = 2π · a · cos (2πx / l) · (dx · dt)
(DVb / dt) = 2π · a · sin (2πx / l) · (dx / dt)
cos ^ 2 (2πx / l) + sin ^ 2 (2πx / l) = 1
Therefore, Formula (1) can be expressed by Formula (2).
√ ((dVa / dt) ^ 2 + (dVb / dt) ^ 2)
= √ ((dx / dt) ^ 2 · (2πx / l) ^ 2)
= (2πa / l) · (dx / dt) (2)

Thus, since a and l are known constants, the velocity or angular velocity can be calculated by executing the above-described calculation.
Since this speed signal is also output between pulses of the counter, a pulse with high accuracy can be obtained by performing position correction (eg, time signal time integration) by the position signal correction unit using this speed signal. Since the inter-position can be calculated, one-pulse vibration at the time of stopping can be suppressed.
As described above, the conventional second motor control device uses the analog voltage signal to estimate the speed and correct the position between pulses, thereby suppressing one-pulse vibration at the time of stoppage.

Japanese Patent Laying-Open No. 2007-252093 (page 2-3, FIG. 1) JP 2008-117262 A (page 3-4, FIG. 1)

In the first conventional motor control device, the motor is within ± 1 pulse. However, when the motor is coasting at a certain speed or when a disturbance is applied even in the stopped state, it is actually 1 pulse in the stopped state. Since there is a dead zone even when a deviation occurs, the control calculation does not work, and as a result, there is a problem that a deviation of 2 pulses or more occurs.
In addition, the conventional second motor control device newly calculates the speed from the two-phase analog signal of the position detector with respect to the normal control device, and transmits the calculated speed using A / D, D / A, it is necessary to add new hardware such as an amplifier, a transmission cable, etc., and there is a problem that the cost increases.

The present invention has been made in view of such a problem. When the current is within 1 pulse, the sign of the speed is estimated from the detected current value, and a current compensation signal having a pattern according to the sign of the speed is provided. It is an object of the present invention to provide a motor control device that can reliably and stably reduce vibration at the time of stopping by compensating for the current command value.

In order to solve the above problems, the present invention is configured as follows.
A motor control device according to an aspect of the present invention includes a current detector that detects a current supplied to a motor having a position detector, a position command and a position detection value, and the position command and the position detection value. A position / velocity control unit that outputs a current command by performing a control calculation so as to match, and a current that outputs a voltage command so that the current command and the current detection value are matched by inputting the current command and the current detection value A control unit, and a speed direction detection unit that detects and outputs a sign of speed based on the detected current value, and determines that the motor is stopped within ± 1 pulse. A stop determination unit for setting a stop state, and a compensation signal calculation unit for calculating and outputting a current compensation signal for compensating the current command according to the sign of the speed only when the stop determination unit sets the stop state. Equipped motor Your device is applied.

According to the first to ninth aspects of the present invention, when a motor that is not normally controlled is within ± 1 pulse, a specific current command pattern is calculated so that only the sign of the speed is calculated and the operation of the motor is suppressed. Is compensated in the direction opposite to the sign of the speed, a phenomenon in which the motor moves more than one pulse can be avoided, and as a result, vibration of one pulse at the time of stopping can be suppressed.
According to the first aspect of the present invention, since the speed can be calculated from the mathematical model of the motor using only the current detection value and the sign can be calculated, the vibration of one pulse at the time of stopping can be suppressed with a small amount of calculation. Can do.
According to the second aspect of the present invention, the sign of the speed can be calculated simply by filtering the current detection value and performing integral calculation using the characteristic that the current detection value is proportional to the torque and acceleration. The vibration of one pulse at the time of stop can be suppressed by the amount of calculation.
Further, according to the invention described in claims 3 to 5 or 7 to 9 , one pulse at the time of stoppage can be easily and stably compensated by compensating the current command value determined in advance according to the sign of the speed. Vibration can be suppressed.
According to the invention described in claim 6 , in order to determine the sign by using the characteristic that the induced voltage is estimated by the observer from the voltage command and the current detection value, and the induced voltage is a value proportional to the speed, Even when the mathematical model of the motor deviates from the actual machine, the correction is applied by the observer, so the sign of the speed can be calculated with high accuracy, and the effect of suppressing the vibration at the time of stopping can be further enhanced.

The block diagram of the motor control apparatus which shows 1st Example of this invention. The block diagram of the motor control apparatus which shows 2nd Example of this invention. The block diagram which shows an example of the position / speed control part of the Example of this invention The block diagram which shows an example of the current control part of the Example of this invention The block diagram which shows the mathematical model of the motor of this invention (A) The figure which shows the 1st pattern of the current compensation signal comp of this invention (b) The figure which shows the 2nd pattern of the current compensation signal comp of this invention (c) The 3rd of the current compensation signal comp of this invention Diagram showing pattern (A) Waveform diagram when the present invention is not applied (b) Waveform diagram when the present invention is applied Configuration diagram of conventional first motor control device Configuration diagram of conventional second motor control device

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a motor control apparatus showing a first embodiment of the present invention. In the figure, 1 is a motor, 2 is a current detector, 3 is a position detector, 4 is a current control unit, 5 is a position speed control unit, 6 is a speed direction detection unit, 7 is a compensation signal calculation unit, and 8 is a stop determination. Represents a part.
The current control unit 4 performs a control calculation so that the current command Ir and the current detection value I coincide with each other, and outputs a voltage command V. The position speed control unit 5 performs a control calculation so that the position command ref and the position detection value x match, and outputs a current command value Iref. The speed direction detector 6 calculates the sign of the speed when the motor is within ± 1 pulse. The stop determination unit 8 determines whether or not the motor is in a stop state between ± 1 pulse. The compensation signal calculation unit 7 outputs a current compensation signal comp having a pattern determined in advance according to the sign of the speed only when it is determined to be in a stopped state. The current compensation signal comp is subtracted from the current command Ir, and the compensated current command Ir is input to the current control unit 4.
The present invention is different from the prior art in that it includes a speed direction detection unit 6, a compensation signal calculation unit 7, and a stop determination unit 8.

Details of each component shown in FIG. 1 will be described below with reference to the drawings.
FIG. 3 is a block diagram showing details of the position / speed controller 5. Kp is a position control proportional gain, Kv is a speed control proportional gain, Ki is a speed control integral gain, Jn is a moment of inertia nominal value Kt is a torque constant, and s is a Laplace operator.
The position speed control unit 5 inputs the command ref and the position detection value x, calculates the equation (8) from the equations (3), and finally calculates the current command value Iref.
vref = Kp · (ref−x) (3)
vfb = x · s (4)
aref = Kv · (vref−vfb) (5)
sref = Ki · aref / s (6)
tref = Jn · (aref + sref) (7)
Iref = tref / Kt (8)
Next, a current command value Ir to be input to the current control unit 4 is obtained by subtracting a later-described current compensation signal comp from Iref calculated by the position / speed control unit 5 using Equation (9).
Ir = Iref−comp (9)

FIG. 4 is a block diagram showing details of the current control unit 4. KpI represents a current control proportional gain and a KiI current control integral gain.
The current control unit 4 inputs the current command Ir and the current detection value I, calculates the formula (12) from the formula (10), and finally outputs the voltage command V.
Iaref = KpI · (Ir−I) (10)
Isref = KiI · Iaref / s (11)
V = Iaref + Isref (12)

FIG. 5 is a block diagram showing a motor model. 51 represents an electric circuit part, L represents an inductance, and R represents a resistance. Kt of 52 represents a torque constant, and converts current and torque. 53 represents a motor machine model, and J represents a motor moment of inertia. Reference numeral 54 denotes an integrator, which integrates the motor speed ω with time to obtain the motor position x. Ke of 55 represents an induced voltage constant and generates an induced voltage E proportional to the speed.
The speed direction detection unit 6 in FIG. 1 determines the sign of speed using the model in FIG. As can be seen from FIG. 5, the speed ω is obtained by multiplying the current value I by Kt and 1 / (J · s). Here, ω may be calculated using the values of Kt and J, but in reality, Kt and J are constants and are not related to the sign. Therefore, as in equation (13), the sign of the speed can be understood by examining the sign of the signal obtained by integrating the current value I over time.
sgn = sgn {∫Idt} (13)

Further, when there is a constant disturbance or the like, an offset corresponding to the constant disturbance is superimposed on the current command Ir, so that the integral value increases when integrated. In order to avoid this, the sign of velocity may be derived by detecting the sign of the integrated signal after passing the current value I through a high-pass filter in order to remove a constant disturbance.
Furthermore, when determining the code, if the signal to be determined has noise and is erroneously detected when the signal has a small value, a dead zone may be provided in the signal to be determined.
In this way, the processing of the speed direction detection unit 6 in FIG. 1 can be configured in any way as long as it is a method that can determine the sign of speed.

FIG. 6 is a diagram illustrating a pattern of the current compensation signal comp generated by the compensation signal calculation unit 7. In the compensation signal calculation unit 7, only when the stop determination unit 8 determines that the motor is stopped within ± 1 pulse, according to the speed code sgn detected by the speed direction detection unit 6. 6 generates a current compensation signal comp having a pattern as shown in (a), (b), and (c) of FIG.
Although the best pattern of the current compensation signal comp varies depending on the characteristics of the motor 1 and the current control unit 4 and the like, the pattern may be set in advance by trial and error, but in most cases, (a) and (b) in FIG. ) Or (c) is effective. (A) is a rectangular pulse having a size G corresponding to the sign of the speed. The value of G is obtained by adjustment. (B) and (c) are patterns in which the current compensation signal comp is gradually increased or decreased at a certain ratio while the codes continue in the same direction. The ratio may be determined according to the effect such as 0.9 or 1.2. Further, the value of G or the ratio may be changed according to the moment of inertia and the number of encoder bits.
Moreover, you may add the offset of the magnitude | size which exists in the pattern of (a) (b) (c) mentioned above. The offset value may be adjusted, for example, an offset corresponding to the magnitude of the value of the current command Iref at the moment of entering the stop state may be added.

The process of the stop determination unit 8 may be any process as long as it can be determined that the motor 1 is stopped within ± 1 pulse. For example, the position command and the position detection value are monitored, What is necessary is just to discriminate | determine whether a position detection value exists in less than +/- 1 pulse in the state in which instruction | command has not generate | occur | produced.

7A is a waveform diagram of position response and position deviation when the present invention is not applied, and FIG. 7B is a waveform diagram of position response and position deviation when the present invention is applied. When the present invention is not used, ± 1 pulse vibration is continuously generated at the time of stopping, but it can be seen that ± 1 pulse vibration at the time of stopping is suppressed by using the present invention.
In this way, when the motor that is normally not controlled is within ± 1 pulse, only the sign of the speed is calculated, and the specific current command pattern is opposite to the sign of the speed so as to suppress the operation of the motor By compensating for the above, it is possible to avoid the phenomenon that the motor moves more than one pulse, and as a result, it is possible to suppress the vibration of one pulse when stopped.

FIG. 2 is a block diagram of a motor control apparatus showing a second embodiment of the present invention. The difference from the first embodiment is that not only the current detection value I but also a voltage command V is added to the speed direction detection unit 6. In this embodiment, when the speed direction detection unit 6 detects the speed code sgn, an observer is formed from the voltage command V and the current detection value I to estimate the induced voltage estimated value. Since the induced voltage is a constant proportional to the speed, the sign of the speed is checked by determining the sign of the induced voltage estimated value.
The observer for estimating the induced voltage used in the speed direction detection unit 6 in FIG. 1 calculates the estimated value Ehat of the induced voltage E as shown in the following equation (14) using the model in FIG.
Ehat = g / (s + g) · {I · (Ls + R) −V} (14)
Moreover, you may comprise in the simplified form like Formula (15).
Ehat = IV / (Ls + R) (15)
Here, g represents an observer estimated gain, and it may be set to a large value such that the waveform of the induced voltage estimated value does not become dirty due to the influence of noise.
In this way, the induced voltage is estimated by the observer from the voltage command Ir and the detected current value I, and the sign of the speed sgn is determined using the characteristic that the induced voltage is a value proportional to the speed. Even when the target model deviates from the actual machine, correction is applied by the observer, so that the speed code sgn can be calculated with high accuracy, and the effect of suppressing vibration at the time of stopping can be further enhanced.

During digital control, the speed sign is calculated from the current detection value when the motor is within ± 1 pulse, and the vibration at stop is applied by adding a current compensation value in the direction opposite to the speed sign so as not to operate more than ± 1 pulse. Therefore, it can be applied not only to a rotating machine but also to a linear motion linear motor.

DESCRIPTION OF SYMBOLS 1 Motor 2 Current detector 3 Position detector 4 Current control part 5 Position / speed control part 6 Speed direction detection part 7 Compensation signal calculation part 8 Stop determination part 31 Position control proportional gain 32 Speed control proportional gain 33 Integration controller 34 Inertia Moment nominal value 35 Reciprocal of torque constant Kt 41 Current control proportional gain 42 Current control integral gain 51 Motor electrical circuit 52 Torque constant 53 Motor machine 54 Integration 55 Induced voltage constant 81 Motor 82 Encoder 83 Speed detection circuit 84 Position deviation calculation circuit 85 Speed Deviation calculation circuit 86 Torque command generation circuit 87 Motor stop determination circuit 88 Dead band formation circuit 91 Control device 92 Detector 93 Servo motor 94 Position detector 95 Square wave generator 96 Position counter 98 Position signal correction unit

Claims (9)

A current detector that detects the current supplied to a motor having a position detector, and a position command and a position detection value are input, a control calculation is performed so that the position command and the position detection value match, and a current command is output. In a motor control device comprising: a position / speed control unit, and a current control unit that inputs the current command and the current detection value and outputs a voltage command so that the current command and the current detection value match.
A speed direction detector that detects and outputs a sign of speed based on a sign of a signal obtained by time-integrating the current detection value;
A stop determining unit that determines that the motor is stopped within ± 1 pulse and sets the motor to a stopped state;
A motor control comprising: a compensation signal calculation unit that calculates and outputs a current compensation signal for compensating the current command according to the sign of the speed only when the stop determination unit is in a stop state. apparatus. A current detector that detects the current supplied to a motor having a position detector, and a position command and a position detection value are input, a control calculation is performed so that the position command and the position detection value match, and a current command is output. In a motor control device comprising: a position / speed control unit, and a current control unit that inputs the current command and the current detection value and outputs a voltage command so that the current command and the current detection value match.
A speed direction detector that detects and outputs a sign of speed based on the detected current value;
A stop determining unit that determines that the motor is stopped within ± 1 pulse and sets the motor to a stopped state;
A compensation signal calculation unit that calculates and outputs a current compensation signal for compensating the current command according to the sign of the speed only when the stop determination unit is in a stop state;
A high-pass filter,
The motor control device, wherein the speed direction detection unit detects a sign of the speed based on a sign of a signal integrated after passing the current detection value through the high-pass filter. A current detector that detects the current supplied to a motor having a position detector, and a position command and a position detection value are input, a control calculation is performed so that the position command and the position detection value match, and a current command is output. In a motor control device comprising: a position / speed control unit, and a current control unit that inputs the current command and the current detection value and outputs a voltage command so that the current command and the current detection value match.
A speed direction detector that detects and outputs a sign of speed based on the detected current value;
A stop determining unit that determines that the motor is stopped within ± 1 pulse and sets the motor to a stopped state;
A compensation signal calculation unit that calculates and outputs a current compensation signal for compensating the current command according to the sign of the speed only when the stop determination unit is in a stop state,
The motor controller according to claim 1, wherein the current compensation signal is a predetermined current pattern corresponding to the sign of the speed. 4. The motor control device according to claim 3 , wherein the current pattern is a rectangular signal having a certain size. 4. The motor control apparatus according to claim 3 , wherein the current pattern is a pattern signal that increases or decreases the current compensation signal with a certain inclination. A current detector that detects the current supplied to a motor having a position detector, and a position command and a position detection value are input, a control calculation is performed so that the position command and the position detection value match, and a current command is output. In a motor control device comprising: a position / speed control unit, and a current control unit that inputs the current command and the current detection value and outputs a voltage command so that the current command and the current detection value match.
A speed direction detection unit that calculates an induced voltage estimated value based on the voltage command and the current detection value, detects a sign of speed based on the sign of the induced voltage estimated value, and outputs the detected speed sign;
A stop determining unit that determines that the motor is stopped within ± 1 pulse and sets the motor to a stopped state;
A motor control comprising: a compensation signal calculation unit that calculates and outputs a current compensation signal for compensating the current command according to the sign of the speed only when the stop determination unit is in a stop state. apparatus. A current detector that detects the current supplied to a motor having a position detector, and a position command and a position detection value are input, a control calculation is performed so that the position command and the position detection value match, and a current command is output. In a motor control device comprising: a position / speed control unit, and a current control unit that inputs the current command and the current detection value and outputs a voltage command so that the current command and the current detection value match.
A speed direction detector that detects and outputs a sign of speed based on the voltage command and the current detection value;
A stop determining unit that determines that the motor is stopped within ± 1 pulse and sets the motor to a stopped state;
A compensation signal calculation unit that calculates and outputs a current compensation signal for compensating the current command according to the sign of the speed only when the stop determination unit is in a stop state,
The motor controller according to claim 1, wherein the current compensation signal is a predetermined current pattern corresponding to the sign of the speed. 8. The motor control device according to claim 7 , wherein the current pattern is a rectangular signal having a certain size. 8. The motor control device according to claim 7 , wherein the current pattern is a pattern signal that increases or decreases the current compensation signal with a certain inclination.

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