JP2002233178A - Motor control device and motor control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device and a motor control method which can find out early a position detection abnormality in feedback positioning control of a servomotor, and protect an apparatus driven by the servomotor. SOLUTION: Origin signals are always monitored, and counted values of pulses of rotation detection signals of a motor are stored in matching with the timings of the generation of the origin signals. If the difference between the present counted value and the counted value previously stored and a count reference value per turn of the motor are not equal to each other, an abnormality detection signal is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device and a motor control method for controlling the positioning of a servomotor at a desired position.

[0002]

2. Description of the Related Art Feedback control of a servomotor is performed,
In a motor control device for positioning at a desired position, it is important to perform positioning control for a servomotor with high accuracy. In order to realize a motor control device capable of performing high-accuracy positioning control, it is necessary to increase the resolution of an encoder attached to a servomotor and increase the frequency characteristics in feedback control.

Hereinafter, a conventional motor control device will be described with reference to FIG.
This will be described with reference to a block diagram showing the configuration of the motor control device. As shown in FIG. 3, an encoder 2 is attached to an output section directly connected to the mover of the servo motor 1. The encoder 2 outputs an A-phase signal and a B-phase signal corresponding to the rotation amount of the mover of the servomotor 1 as pulse signals. This encoder 2 is a servo motor 1
An origin signal that generates one pulse for one rotation of is output as a pulse signal. Motor controller position / speed detector 3
And encoder 2 are connected by a signal line 2a, and an A-phase signal, B
The phase signal and the origin signal are input to the position / speed detector 3. The position / speed detector 3 counts the number of pulses of the A-phase signal or the B-phase signal, thereby detecting the current position θm and the rotation speed ω based on the rotation amount of the servomotor 1.

The position controller 4 compares a position command θmd given from outside the motor control device with a current position θm detected by the position / speed detector 3.
When there is a position deviation between the position command θmd and the current position θm, the position controller 4 calculates the position deviation amount Δθ of the position deviation.
Is multiplied by a predetermined position gain to obtain a motor rotation speed command ω.
Output to the speed controller 5 as d. In the speed controller 5, the motor rotation speed command ω input from the position controller 4
d and the rotational speed ω detected by the position / speed detector 3
Is compared with When there is a deviation between the motor rotation speed command ωd and the rotation speed ω, the speed controller 5 sends a signal obtained by multiplying the difference by a predetermined speed gain to the current amplifier 6 as a current command value (torque command) iq. Output. A command voltage output from the current amplifier 6 based on the current command value iq is applied to each phase of the bridge circuit forming the PWM inverter 7.

When a command voltage is applied to each phase of the bridge circuit of the PWM inverter 7, a current flows through the stator winding of the servo motor 1, and the mover of the servo motor 1 moves by a predetermined amount. When the mover of the servo motor 1 reaches the position of the position command θmd given from outside the motor control device and the rotation speed ω becomes zero, the outputs of the position controller 4 and the speed controller 5 become zero. And the current command value (torque command) i
q becomes zero, the servomotor 1 stops, and the positioning operation is completed.

An origin signal that generates one pulse per rotation of the servomotor 1 is used to detect a motor reference position (origin) when performing a positioning operation. When power is supplied to the motor control device, an origin return operation is executed based on an origin signal to perform a positioning operation at a motor reference position (origin), thereby enabling a mechanically-positioning operation at the same position.

[0007]

In the conventional servo motor positioning control method, the position detection accuracy is improved by increasing the resolution of an encoder attached to the servo motor in order to perform high-speed and high-accuracy positioning. I was letting it. Further, in the motor control device, the frequency characteristic of the feedback control circuit has been enhanced with respect to the increase in the frequency of the rotation amount signal accompanying the improvement in resolution of the encoder.

The rotation amount signal detected by the encoder is connected via a signal line to be taken into the motor control device. However, when the motor is rotating at high speed,
If the frequency of the position detection signal from the encoder is high,
There was a possibility that noise was superimposed on the position detection signal due to the influence of the use environment of the servomotor. In the conventional motor control device, the pulse waveform of the position detection signal detected by the encoder is disturbed, the position / speed detector erroneously counts the number of pulses, and the motor is positioned at an erroneous position by feedback control. However, the abnormality cannot be detected inside the motor control device. as a result,
Due to the displacement, there has been a problem that the positioning accuracy is deteriorated and a device connected to the servomotor is damaged. Further, there is a problem that it is difficult to identify the cause of the displacement even if it occurs.

According to the present invention, when an abnormality occurs in a position detection signal detected by an encoder, the abnormality is detected at an early stage,
An object of the present invention is to provide a motor control method and a motor control device capable of protecting a device connected to a servomotor.

[0010]

In order to achieve the above object, a motor control device of the present invention detects a rotation amount of a motor and outputs a pulse-like rotation amount signal, and a rotation amount detector for the motor. A position detector having an origin detector that detects one origin position existing during one rotation of the motor and outputs an origin signal, and moves the motor to a desired position based on the rotation amount signal and the origin signal. What is claimed is: 1. A motor control device for performing positioning control so as to operate, counting means for counting the number of pulses of the rotation amount signal, constantly monitoring the origin signal, and generating a count timing signal in accordance with the generation timing of the origin signal. Origin signal monitoring means, a count value storage means for storing a count value of the number of pulses counted by the counting means based on the count timing signal as a storage count value, and The difference between the count value stored in the means and the stored count value stored one revolution before is compared with the count reference value per motor rotation. If the difference is not equal to the count reference value, an abnormality is detected. A motor position detector abnormality detecting means for outputting a detection signal is provided.

In the motor control device having this configuration, the fact that the pulse count value of the rotation amount signal detected between the origin signal and the origin signal always coincides with the number of pulses output from the encoder per one rotation inherent to the motor is utilized. are doing. This makes it possible to reliably detect an abnormality within one rotation of the motor.

According to the motor control method of the present invention, a step of detecting a rotation amount of a motor and outputting a pulse-like rotation amount signal, and detecting an origin position existing in one rotation of the motor, A motor control method for controlling a position of the motor based on the rotation amount signal and the origin signal so as to operate the motor to a desired position, and counting a number of pulses of the rotation amount signal. Outputting the count value, constantly monitoring the origin signal, outputting a count timing signal in accordance with the generation timing of the origin signal, storing the count value as a storage count value based on the count timing signal. A step, and a difference between the count value and the stored count value stored one revolution before;
A step of comparing a count reference value per rotation and outputting an abnormality detection signal when the difference is not equal to the count reference value.

According to the motor control method having this configuration, the pulse count value of the rotation amount signal detected between the home position signals always coincides with the number of pulses output from the encoder per one rotation inherent to the motor. We are utilizing. This makes it possible to reliably detect an abnormality within one rotation of the motor.

In the motor control device and the control method having the above-described configurations, a difference between the count value and the stored count value one rotation before is compared with a count reference value per one rotation of the motor.
An abnormality detection signal may be output when the difference between the difference and the count reference value is equal to or greater than a predetermined value. By improving the resolution of the encoder, if the range of the number of pulses that does not cause an abnormality in the device connected to the motor is allowed, an abnormality detection signal is output according to the allowable number of pulses. can do.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a motor control device and a motor control method according to the present invention will be described below with reference to the accompanying drawings.

Embodiment FIG. 1 is a block diagram showing the configuration of a motor control device according to an embodiment of the present invention. In FIG. 1, an encoder 2 is attached to an output section directly connected to a mover of a servo motor 1. This encoder 2
Outputs an A-phase signal and a B-phase signal corresponding to the rotation amount of the mover of the servomotor 1 as pulse signals. The encoder 2 outputs an origin signal that generates one pulse per one rotation of the servomotor 1.

The position / speed detector 3 of the motor controller is connected to the encoder 2 via a signal line 2a, and an A-phase signal, a B-phase signal, and an origin signal are input to the position / speed detector 3. The position / speed detector 3 detects the current position θm and the rotation speed ω based on the rotation amount of the servo motor 1 by counting the number of pulses of the A-phase signal or the B-phase signal. The position controller 4 compares the position command θmd given from outside the motor control device with the current position θm detected by the position / speed detector 3. When there is a position deviation between the position command θmd and the current position θm, the position controller 4 sets a signal obtained by multiplying the position deviation Δθ of the position deviation by a predetermined position gain as a motor rotation speed command ωd. Output to 5

The speed controller 5 compares the motor rotation speed command ωd input from the position controller 4 with the rotation speed ω detected by the position / speed detector 3. When there is a deviation between the motor rotation speed command ωd and the rotation speed ω, the speed controller 5 sends a signal obtained by multiplying the difference by a predetermined speed gain to the current amplifier 6 as a current command value (torque command) iq. Output. The current amplifier 6 calculates the current command value i
The command voltage is applied to each phase of the bridge circuit constituting the PWM inverter 7 based on q. When a command voltage is applied to each phase of the bridge circuit of the PWM inverter 7, a current flows through the stator winding of the servomotor 1, and the mover of the servomotor 1 moves by a predetermined amount.

When the mover of the servo motor 1 reaches the position command θmd given from outside the motor control device,
When the rotation speed ω becomes zero, the outputs of the position controller 4 and the speed controller 5 become zero. At this time, the current command value (torque command) iq becomes zero, the servomotor 1 stops, and the positioning operation is completed.

An origin signal that generates one pulse per rotation of the servomotor 1 is used to detect a motor reference position (origin) when performing a positioning operation. When power is supplied to the motor control device, an origin return operation is performed based on the origin signal to perform a positioning operation at a motor reference position (origin), thereby enabling a mechanically same positioning operation.

As shown in FIG. 1, the motor control device of this embodiment has a counting section 8, an origin signal monitoring section 9, a count value storage section 10, and a motor position detector abnormality detection section 11. The counting unit 8 always counts the number of pulses of the A-phase signal or the B-phase signal output from the encoder 2. The origin signal monitoring unit 9 constantly monitors the origin signal output from the encoder 2, and when the origin signal is detected, for example, when the pulse of the origin signal is positive logic, the counting unit 8 at the rising edge of the pulse. Output a counting timing signal.

The count value storage unit 10 stores the count value of the pulse of the A-phase signal or the B-phase signal counted by the count unit 8 in accordance with the count timing signal from the origin signal monitoring unit 9 as a storage count value. Motor position detector abnormality detector 1
1 takes out the stored count value stored in the count storage unit 10, calculates the difference between the stored count value one rotation before, and the count reference value Co which is the number of pulses per motor rotation.
Compare with

For example, the storage count value at a certain time is Cn,
The stored count value at the time of the next origin signal generation is Cn + 1,
The calculation is performed by the following equation (1).

ΔC = Co− | Cn + 1−Cn | (1)

As a result, when ΔC is zero, it is determined that the operation is normal, and when ΔC is not zero, it is determined that the operation is abnormal. If it is abnormal, the motor position detector abnormality detector 11 outputs an abnormality occurrence signal to the position controller 4 to stop the servo motor so as not to cause an abnormality in the device connected to the servo motor, The command ωd is set to zero. As a result, the servomotor enters a servo-free state.

Here, the principle of position signal abnormality detection will be described with reference to FIG. In a normal state, as shown in FIG. 2A, the encoder 2 has a constant number (here, n) unique to the encoder 2 during one rotation of the servomotor 1 as an A-phase signal. Outputs a pulse signal. Further, as shown in FIG. 2B, the encoder 2 generates an origin signal every time the servomotor 1 makes one rotation.
Outputs one pulse signal.

Here, as shown in FIG. 2 (c), a case is considered where noise as shown in waveform 1 is superimposed on the A-phase signal. In this case, the A-phase signal is affected by noise,
As shown in waveform 2 of (d), the waveform is disturbed, resulting in a pulse in which the third and fourth pulses of the normal A-phase signal waveform are combined into one. As a result, if the number of pulses during one rotation should be n if it is normal, the number of pulses is counted as n-1 by combining the pulses. As a result, ΔC calculated by Expression (1) becomes 1, and the motor position detector abnormality detection unit 11 outputs an abnormality occurrence signal to the position controller 4.

In the above-described embodiment, an example has been described in which it is determined that an abnormality is present unless ΔC is zero. However, by improving the resolution of the encoder, a device connected to the motor can be used in a pulse that does not cause an abnormality. When a range of numbers is allowed, the expression (1) is set to a value corresponding to the allowed number of pulses.
May be set so that the motor position detector abnormality detection unit 11 outputs an abnormality occurrence signal when the value of ΔC becomes larger than the value of ΔC.

[0029]

As described in detail in the above embodiments, in the motor control method and control device of the present invention, the pulse count value of the position detection signal detected between the origin signals is always applied to the motor. It utilizes the fact that it matches the number of pulses output by the encoder per unique rotation. Therefore, even when the position detection signal is affected by noise, an abnormality can be reliably detected during one rotation of the motor, and the device connected to the motor can be protected. Further, even when the motor is displaced, the cause can be easily specified, and an immediate countermeasure can be taken.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a motor control device according to an embodiment of the present invention.

FIGS. 2A and 2B are waveform diagrams for explaining the principle of detecting a position signal abnormality in the motor control device according to the embodiment of the present invention; FIG. 2A is a waveform diagram of a normal A-phase signal; FIG. (D) Waveform diagram of A-phase signal disturbed by noise

FIG. 3 is a block diagram showing a configuration of a conventional motor control device.

[Explanation of symbols]

 Reference Signs List 1 servo motor 2 encoder 2a connection line 3 position / speed detector 4 position controller 5 speed controller 6 current amplifier 7 PWM inverter 8 counting unit 9 origin signal monitoring unit 10 count value storage unit 11 motor position detector abnormality detection unit

Claims (4)

[Claims] A rotation amount detector for detecting a rotation amount of a motor and outputting a pulse-like rotation amount signal;
A position detector having an origin detector that detects one origin position existing during rotation and outputs an origin signal; and operates the motor to a desired position based on the rotation amount signal and the origin signal. A motor control device that performs positioning control as described above, a counting unit that counts the number of pulses of the rotation amount signal, an origin that constantly monitors the origin signal and generates a counting timing signal in accordance with the generation timing of the origin signal. A signal monitoring unit, a count value storage unit that stores a count value of the number of pulses counted by the counting unit based on the count timing signal as a storage count value, and the count value stored in the count storage unit and one count before rotation. Comparing the difference between the stored stored count value and the count reference value per one rotation of the motor, and when the difference is not equal to the count reference value A motor position detector which outputs an abnormality detection signal to the motor control device. 2. The motor position detector abnormality detecting means according to claim 1, wherein: a difference between a count value stored in said count storage means and said stored count value stored one revolution before; The motor control device according to claim 1, wherein the motor control device compares a reference value and outputs an abnormality detection signal when a difference between the difference and the count reference value is equal to or greater than a predetermined value. 3. A step of detecting a rotation amount of a motor and outputting a pulse-shaped rotation amount signal, and a step of detecting an origin position existing in one rotation of the motor and outputting an origin signal. A motor control method for performing positioning control to operate the motor to a desired position based on the rotation amount signal and the origin signal, and counts the number of pulses of the rotation amount signal and outputs a count value A step of constantly monitoring the origin signal and outputting a count timing signal in accordance with the generation timing of the origin signal; a step of storing the count value as a storage count value based on the count timing signal; and the count value And a difference between the count value and the stored count value stored one revolution before, and a count reference value per one rotation of the motor. If the difference is not equal to the count reference value, a difference is determined. The motor control method characterized by comprising the step of outputting a detection signal. 4. A comparison between a difference between the count value and the stored count value stored one revolution before, and a count reference value per one rotation of the motor, and a difference between the difference and the count reference value. 4. The motor control method according to claim 3, further comprising a step of outputting an abnormality detection signal when is greater than or equal to a predetermined value.