JPH087840Y2 - Servo motor origin positioning device - Google Patents

Description

[Detailed Description of the Invention] A. Industrial Application Field The present invention relates to a home position locating device for a servo motor,
In particular, the present invention relates to a driver device that controls the rotational drive of a synchronous motor by an inverter.

B. Outline of the device In a servo motor driver that does not use an encoder that uses a synchronous motor, the most significant bit from the counter is output to the ROM that outputs the sine wave output waveform for controlling the inverter that drives this synchronous motor. The origin signal is created in the driver by using the origin positioning signal.

C. Conventional technology and its problems In a linear motion positioning device, in a system that uses a synchronous motor (servo motor) (hereinafter referred to as a motor) to convert rotation to linear motion with a ball screw, before performing positioning operation. It is always necessary to determine the machine origin, which is most simply the position where the carriage with the ball nut actuates the limit switch.

In this case, the ball screw and the ball nut have sufficiently high precision, but the limit switch is usually a proximity switch (non-contact) and is durable, so the precision is not good.

Therefore, as shown in FIG. 7, after the encoder 02 is directly connected to the motor 01 and the moving base 04 that linearly moves with respect to the ball screw 03 actuates the limit switch 05, the Z-phase signal of the rotary encoder 02 (normally Positioning accuracy is improved by determining the output position of a signal for outputting one pulse per rotation) as an origin, and counting the A phase and B phase pulses of the encoder 02 starting from this origin.

However, the use of this encoder 02 makes the device complicated and expensive, and the encoder has poor environmental resistance,
In addition, there is a problem that noise is easily picked up in a cable connection between the encoder and the control device.

Therefore, the present invention provides an origin positioning device for a servo motor, which does not use an encoder for origin positioning, thereby preventing the device from becoming complicated and having excellent environmental resistance, and also preventing noise from being generated.

D. Means for Solving the Problems The present invention which achieves the above-mentioned object is a counter for counting the oscillation output, and a counter which is connected to this counter and which is quantized and stored by addressing with this count output. In a circuit having a ROM that outputs a sine wave system and an inverter that controls a motor by controlling a sine waveform based on this ROM by comparing the output with a triangular wave, the most significant bit signal is output from the counter to the ROM. A connection line is formed to output, and the position where the highest bit signal is output after turning on the limit switch attached to the driving machine is the origin position and the rotation angle of the motor is determined by the output of the highest bit signal. I decided to decide.

E. Action After the limit switch is activated, if the highest count value of the counter is applied to the origin, accurate origin positioning is possible.

F. Embodiment An embodiment of the present invention will now be described with reference to FIGS.

Figure 1 shows the PWM (Pulse Width Modulation) which is the basis of this invention.
The control system which drives a synchronous motor with the inverter of the system is shown.

The output obtained by rectifying the AC power supply by the rectifier 1 becomes the input of the power transistor type inverter 2, and the AC output produced by the inverter 2 is applied to the armature winding of the rotating field type synchronous motor 3.

In this case, the structure of the synchronous motor 3 is a synchronous motor in which a permanent magnet 3a is built in the rotor as shown in FIG. 2, and the armature winding 3b is arranged in the stator.

Returning to FIG. 1, the inverter 2 is controlled by the PWM control device 4. In the control device 4, the oscillator 41 oscillates at a frequency according to the frequency command signal a from the command unit 40. This oscillation output is input to and counted by two counters 42 and 43, respectively.

The digital count output of the counter 42 becomes the address input of the sine wave waveform memories 61, 62, 63 composed of ROM. The same sine wave waveform is quantized and stored in these three waveform memories 61, 62 and 63. However, each waveform memory 61, 62, 63
The memory waveforms of are out of phase by 120 °. The digital output read from each waveform memory 61, 62, 63 is D /
The A converters 71, 72, 73 convert the analog sine wave signals r, s, t.

The count output of the counter 43 becomes an address input of the triangular wave waveform memory 64. The digital output of this memory 64
A triangular wave signal d is obtained by analog conversion in the D / A converter 74.

FIG. 3 shows the relationship between the sine wave signals r, s, t and the triangular wave signal d described above. The frequency of these signals changes in proportion to the frequency of the oscillator 41. However, in this embodiment, the frequency of the triangular wave signal d is set to be 6 times the frequency of the sine wave signals r, s, t.

Further, the voltage command signal c from the command unit 40 is transmitted to each D / A converter 7
The gain control signal is 1,72,73, and the amplitude of the sine wave signals r, s, t is controlled by this signal c.

The sine wave signals r, s, t and the triangular wave signal d are respectively compared by the comparator 8
1, 82 and 83 are compared, and a non-uniform width pulse train as shown in FIG. 3 is created. In FIG. 3, only the sine wave signal r and the triangular wave signal d are shown. The inverter 2 is controlled by the outputs of these comparators 81, 82, 83, and the output voltage of the inverter 2 becomes a PWM signal of a sine wave approximation shown in FIG. 4 and is applied to the electric motor 3.

The voltage output of each phase of the inverter 2 is a sinusoidal approximation signal composed of 6 unequal width pulse trains in which one cycle is divided into six equal parts and one pulse is included in each of the six phase sections P1 to P6. Moreover, there is a phase difference of 120 ° between each phase.

As a result, in FIG. 4, the combination of the sine waveforms in each section of P1 to P6 is determined, so that the rotational position of the rotor can be specified by detecting the combination. For example, as shown in FIG. 5, when advancing the phase from the P ₁ position (corresponding to P _{1 in} FIG. 4) to the P ₂ position by θ, by replacing section P ₁ in FIG. 4 with a combination of section P ₂ The rotating magnetic field is θ
And the rotor rotates by θ. In this way,
The rotation position of the rotor can be detected without the conventional encoder.

Next, in the encoderless servomotor described above, the configuration of FIG. 6 is adopted for the origin positioning. That is, in the PWM control device shown in FIG.
The OM 61 (similar to the ROMs 62 and 63, but omitted in FIG. 6) is provided with the most significant bit line BL for detecting the count of the maximum count value of the counter 42. That is, the counter 42 is counted up, and the sine wave information in the ROM 61 is sequentially addressed and read, D / A converted and compared with the triangular wave. Therefore, when the pulse count of the counter 42 is performed by θ degrees, the information values of the sine wave from 0 degrees to θ degrees are sequentially read from the ROM 61 accordingly. Since the most significant bit signal of the counter output is inverted only once per one revolution of the motor, the rotation angle of the motor is accurately determined by the output of this most significant bit signal. Therefore, the limit switch shown in FIG.
After 05 is activated, the next most significant bit signal is output, which makes it possible to perform home positioning with the highest accuracy, which is the same as the Z signal of the encoder.

Although FIG. 2 shows an example of a two-pole motor, the same Z-phase signal can be generated even with multiple poles, and P / 2 P-phase / rotation Z-phase signal can be obtained.

G. Effect of the Invention As described above, according to the present invention, the origin signal can be generated in the driver, and the conventional encoder is not required, so the device can be simplified, the environment resistance can be provided, and the noise can be improved. It is also effective in reducing the occurrence of.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a control system, FIG. 2 is a configuration diagram of a motor, FIG. 3 is a control signal waveform diagram during rotational driving, FIG. 4 is an output waveform diagram of an inverter, and FIG. 5 is a rotation angle of the motor. 6 is a partial configuration diagram of the control system, and FIG. 7 is a conventional configuration diagram. In the figure, 42 is a counter, 61, 62 and 63 are ROMs, and BL is the most significant bit line.

Claims (1)

[Scope of utility model registration request] 1. A counter for counting oscillation output, and a ROM connected to this counter for outputting a sine waveform quantized and stored by addressing with this count output.
And a circuit that has an inverter that controls the motor by controlling the output of the sine waveform based on this ROM compared with a triangular wave, and forms a connection line so that the most significant bit signal is output from the counter to the ROM. The servo is characterized in that the rotation angle of the motor is determined by the output of the most significant bit signal, with the position at which the most significant bit signal is first output after turning on the limit switch attached to the driven machine as the origin position. Motor origin positioning device.