JPH11113289A - Controller for position control motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a controller for position control motor in which a rotor can be positioned reliably at a commanded position while following up a command without stepping out and the operation is stabilized against fluctuation of load. SOLUTION: The controller for position control motor comprises a section 2 for detecting the rotor position of a position control motor 1, a control section 5 outputting a signal corresponding to a current being supplied to a motor winding depending on the difference between a detection signal from the detecting section 2 and a command position signal, and amplifying sections 6a, 6b outputting the current being supplied to a motor winding in response to an output signal from the control section 5. The control section 5 outputs a sine wave data signal corresponding to the command position signal with reference to a sine wave table when the difference is within 90 deg. by electric angle otherwise outputs a sine wave data signal for exciting such that an excitation stabilizing point is located at a position 90 deg. ahead of the rotor position by electric angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for a position control motor such as a brushless motor or a stepping motor.

[0002]

2. Description of the Related Art Conventionally, as a control device of a position control motor for a brushless motor or a stepping motor of this type, an open-loop control device represented by a stepping motor and a position detector such as an encoder or a resolver are used. There is a closed-loop control device such as an AC servomotor that controls the pressure.

That is, in the case of the open-loop control device,
Regardless of the rotor position, the excitation of the motor is switched by a position command. In the case of the closed-loop control device, the position of the rotor is detected by the position detector, and this is fed back. Usually, the phase of the exciting current of the motor is 90 electrical degrees relative to the rotor position.
制 御 Control is performed so as to reach the stable excitation point.

[0004]

However, in the open-loop control device, when a constant current is applied to the stepping motor, the relationship between the rotor displacement and the generated torque is as shown in FIG. become. Due to the relationship between this displacement and the generated torque, when the displacement reaches 90 °, the generated torque becomes maximum, and within ± 180 °, a torque that attempts to return to its original state is generated, but exceeds ± 180 °. In the range
There is a problem that the rotor generates a torque toward a different stable point without trying to return to the original position, and a displacement occurs. For this reason, when the rotor of the motor cannot follow the switching of the current, the motor loses synchronism, and the reliability of the position control is poor.

On the other hand, in the closed-loop control device, as described above, normally, the phase of the exciting current of the motor is set to an exciting stable point 90 electrical degrees ahead of the rotor position in electrical angle. Is controlled. For this reason, since the position of the rotor does not match the excitation stable point, the rotor cannot be completely stopped, and micro vibration is generated. In addition, the magnitude of the exciting current is controlled with feedback of position, speed, and the like, but there is a delay due to feedback control, so that a loop gain needs to be set.

In this case, (1) with respect to the fluctuation of the load system,
Adjustment of the closed loop gain is required. In order to perform stable control with respect to the fluctuation of the load system, complicated control is required. (2) Slight vibration (hunting) when the rotor stops
There is. (3) There is a problem in that control delay occurs and synchronization with a command is lacking.

[0007] The present invention has been made in view of such a point,
The object is to solve the above-mentioned problems, the rotor follows the command position without step-out, can be positioned with high reliability, is stable against load fluctuation, and vibrates finely when the rotor stops. An object of the present invention is to provide a control device for a position control motor which has no hunting and has good synchronization with a command.

[0008]

According to a first aspect of the present invention, there is provided a position detecting unit for detecting the position of a rotor such as a brushless motor or a stepping motor, a detection signal from the detecting unit and a command position. A control unit that outputs a signal corresponding to a current to be passed through the motor winding based on a deviation of the signal, and an amplification unit that outputs a current passed through the motor winding based on an output signal from the control unit. Consisting of
An apparatus for controlling the position of the motor based on the command position signal is as follows.

(1) The controller outputs a sine wave data signal corresponding to the command position signal using a sine wave table when the deviation is within 90 degrees in electrical angle. When the angle exceeds 90 °, the sine wave table outputs a sine wave data signal that is excited so that the motor becomes an excitation stable point 90 electrical degrees ahead of the rotor position in electrical angle. Features.

(2) In (1), the control unit includes:
A command position counter that counts the pulse signal of the command position signal, a rotor position counter that counts the pulse signal of the position detection signal from the position detection unit, and pulse signals from both counters are input. A phase calculator that outputs an address signal of the sine wave table from a deviation of the pulse signal; and the sine wave table that outputs a sine wave data signal corresponding to the address signal from the phase calculator. The calculating unit outputs the command position pulse signal when the deviation is within 90 ° in electrical angle, and outputs the command pulse signal when the deviation exceeds 90 ° in electrical angle. It is characterized in that the phase is corrected by 90 ° in electrical angle and the position detection pulse signal is output.

(3) In (2), the phase calculator has a function of correcting the speed by adding an appropriate speed correction value to the electrical angle of 90 ° and performing an operation. .

Since the present invention is configured as described above, the deviation between the command position and the detected rotor position is monitored, and the following two modes are provided according to the deviation amount (electrical angle). The mode is switched to one of the modes according to the deviation amount. That is, as shown in FIG. 1, from the relationship between the rotor displacement (position) and the torque generated in the rotor, when (a) -90 ° ≦ deviation amount ≦ + 90 °, the ST mode (stepping (Motor mode), and the excitation state of the motor winding is switched. (B) When −90 °> deviation, + 90 ° <deviation,
In the BL mode (brushless motor mode), excitation is performed so that the phase of the excitation current becomes an excitation stable point 90 ° ahead of the rotor position.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram showing an embodiment of a control device for a position control motor according to the present invention, and FIG. 3 is a block diagram showing a control unit of the control device.

In FIG. 2, reference numeral 1 denotes a two-phase hybrid type stepping motor of a brushless motor, which is provided with 50 rotor small teeth on the outer peripheral surface of the rotor. A rotary shaft of the motor 1 has a position detector 2 for the rotor,
A VR resolver is attached, and the position detector 2
Is supplied with a high-frequency signal of about 100 kHz from the oscillation circuit 3 and outputs a sine wave signal due to a change in the inductance of the sensor pole according to the rotation position of the rotor. The output sine wave signal is converted by the synchronous demodulator 4 into a sine function of the rotation angle of the rotor, and is input to the control unit 5 as a feedback amount.

In FIG. 3, a command position pulse signal input to the control unit 5 and a position detector 2 of the rotor are provided.
And outputs a signal corresponding to the current to be passed through the A-phase and B-phase windings of the motor 1 by comparing the rotor position pulse signal converted into a pulse signal by the position decoder 12 and calculating the deviation. . With this output signal, two-phase power is supplied from the amplifiers 6a and 6b to the A-phase and B-phase windings of the motor 1, respectively, and the position of the motor 1 is controlled by the command position pulse signal.

The control unit 5 has a 32-bit CPU (ce
The output signal as a current command for the A phase and the B phase of the motor 1 is updated at a control cycle of 100 μs using a ntral processor unit. The control unit 5 includes a command position counter 11 for counting command position pulse signals,
A rotor position counter 13 for counting the rotor position pulse signal converted by the position decoder 12 from the position detector 2 and pulse signals from the counters 11 and 13 are input. , A phase calculator 14 for outputting an address signal of the sine wave table 15
And the sine wave table 15 corresponding to the address signal from the phase calculator 14 and outputting a sine wave data signal.

The phase calculator 14 is provided with the two counters 1
When the deviation of the pulse signal from the pulse signals 1, 13 is within 90 ° in electrical angle, an address signal based on the command position pulse signal is output, and a sine wave data signal corresponding to the address signal is output from the sine wave table 15. Is output as a current command. When the deviation exceeds 90 ° in electrical angle, the phase calculator 14 corrects the position detection pulse signal of the motor 1 by 90 ° in electrical angle,
Outputting an address signal based on the position detection pulse signal;
A sine wave data signal corresponding to the address signal is output from the sine wave table 15 as a current command.

FIG. 4A shows the sine wave table 15 corresponding to the A-phase current and the B-phase current of the motor 1.
As shown in FIG. 4B, sine wave data signals for 1000 addresses from 0 to 999 are stored, and a data signal corresponding to the address signal output from the phase calculator 14 is used as a current command. Output. Since the phases of the currents of the A phase and the B phase are shifted by 90 degrees in electrical angle,
The phase current data signal is an address signal obtained by adding 250 to the address signal from the phase calculator 14.

Here, assuming that the output data signal of the sine wave table 15 has addresses 0 to 999 as one cycle, the motor rotates 1/50 rotation (7.2 ° in mechanical angle). Therefore, the rotation amount per address (address 1) is 0.0072 °, and the resolution is 1 / 50,000.
It turns.

The command value of the rotation amount of the motor 1 is input as a pulse signal. This input pulse signal is counted by the command position counter 11 and counts up during normal rotation.
At the time of reverse rotation, a countdown is performed, and a count of 0 to 999 is performed. The rotor position information is fed back as an analog quantity from the position detector 2, converted into a digital quantity by the position decoder 12, and then counted by the rotor position counter 13. The range of the count amount is 0 to 9 similarly to the rotor position counter 13.
99.

The phase calculator 14 constantly monitors the deviation between the command position and the rotor position by subtracting the two count values, and calculates the value of the command position counter 11 and the rotor position counter. The phase of the current flowing through the motor 1 is calculated from the value of 13 and the value of the deviation, and the current phase is output to the sine wave table 15 as an address signal.

The calculation of the current phase is basically performed in the following procedure. When the deviation count value is in the range of ± 250 (± 90 ° in electrical angle), the value of the command position counter 11 is directly output to the sine wave table 15 as the current phase. When the deviation count value exceeds +250, a value obtained by adding 250 to the value of the rotor position counter 13 is output to the sine wave table 15 as a current phase. When the deviation count value exceeds -250, a value obtained by subtracting 250 from the value of the rotor position counter 13 is output to the sine wave table 15 as a current phase. In this case, the value of the rotor position counter 13 is 250
This is the same even if the current is inverted at the value obtained by adding.

Next, when the one motor is actually rotating, a phase delay occurs in the drive current of the motor 1 due to a time delay caused by the calculation time and the winding inductance. The calculation is performed with an appropriate speed correction proportional to the rotation speed of the motor 1 added.

FIG. 5 is a flowchart showing control in the phase calculator 14 and the sine wave table 15 taking into account the speed correction.

The resolution can be changed by changing the count number per pulse of the command position signal by calculation. Further, the current flowing to the motor is 1.5 times during acceleration and deceleration, and 0.5 times when stopped.
The torque required for the positioning operation can be generated while suppressing an increase in the temperature of the motor 1 by changing the operating state.

As described above, according to the present embodiment, the following effects can be obtained. That is, in the case of the open loop control, (1) the control is simple and simple, and the position control can be performed without using a complicated control theory. (2) No hunting during positioning. (3) The delay due to the control is small, and the followability to the command is good. (4) Adjustment is not required for variations in the load system.

Note that the technology of the present invention is not limited to the technology in the above-described embodiment, but may be implemented by means of another embodiment having the same function. Can be changed or added.

[0028]

As is apparent from the above description, according to the position control motor control device of the present invention, the control unit determines whether the deviation between the rotor position and the command position is within 90 degrees in electrical angle. Outputs a sine wave data signal corresponding to the command position signal by a sine wave table, and the deviation is 9 electrical degrees.
When the angle exceeds 0 °, the motor outputs a sine wave data signal which is excited so as to be at an excitation stable point 90 electrical degrees ahead of the rotor position by an electrical angle, using the sine wave table. The rotor follows the motor without step-out, positioning can be performed with high reliability, and it is stable against load fluctuations. There is no micro-vibration (hunting) when the rotor stops, and synchronization with commands is good. can do.

In general, when a stepping motor is used, there is a danger of loss of synchronism. Therefore, the motor is selected in consideration of a large safety factor. However, according to the present invention, there is no danger of loss of synchronism. And a smaller stepping motor can be used.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a displacement and a generated torque of a position control motor rotor of the present invention and modes thereof.

FIG. 2 is a block diagram showing an embodiment of a control device for a position control motor according to the present invention.

FIG. 3 is a block diagram of a control unit of the control device.

FIG. 4A is a diagram showing a relationship between an address signal value and a sine wave data signal value corresponding to an A-phase current value in a sine wave table, and FIG. FIG. 9 is a diagram showing a relationship between an address signal value and a sine wave data signal value corresponding to a B-phase current value.

FIG. 5 is a flowchart of a control that takes into account motor speed correction in a phase calculator and a sine wave table.

FIG. 6 is a diagram showing a relationship between displacement of a conventional position control motor rotor and generated torque.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 2-phase stepping motor 2 Position detector 5 Control part 6a, 6b Amplifier 11 Command position counter 12 Position decoder 13 Rotor position counter 14 Phase calculation part 15 Sine wave table

Claims (3)

[Claims] 1. A position detecting unit for detecting a rotor position such as a brushless motor or a stepping motor, and a detection signal from the detecting unit is compared with a command position signal. A control unit that outputs a signal corresponding to the current; and an amplification unit that outputs a current flowing through the motor winding based on an output signal from the control unit. The position of the motor is controlled by the command position signal. In the device, the control unit outputs a sine wave data signal corresponding to the command position signal by a sine wave table when the deviation is within 90 degrees in electrical angle, and the deviation is 90 degrees in electrical angle.
When the angle exceeds ゜, the motor outputs a sine wave data signal, which is excited so as to be an excitation stable point at an electrical angle of 90 ° ahead of the rotor position, by the sine wave table. Position control device for position control motor. 2. The control section includes: a command position counter for counting a pulse signal of the command position signal; a rotor position counter for counting a pulse signal of the position detection signal from the position detection section; And a phase calculator for outputting an address signal of the sine wave table from a difference between the two pulse signals, and outputting a sine wave data signal corresponding to the address signal from the phase calculator. The phase calculation unit outputs the command position pulse signal when the deviation is within 90 degrees in electrical angle, and the deviation is:
2. The position control according to claim 1, wherein when the electric angle exceeds 90 [deg.], The position detection pulse signal of the motor is corrected by 90 [deg.] In electric angle and the position detection pulse signal is output. Motor position control device. 3. The phase calculation unit performs an operation by adding an appropriate speed correction value to an electrical angle of 90 °,
3. The position control device for a position control motor according to claim 2, further comprising a speed correction function.