JPH08182377A - Circuit for automatic phase correction of synchronous motor - Google Patents

Abstract

PURPOSE: To provide a simple, highly-accurate and economical automatic current phase correction circuit for synchronous motor which detects the phases of field pole detecting signals and inverter driving signals in an on-line state. CONSTITUTION: An automatic current phase correction circuit for synchronous motor detects the position of the magnetic pole of a synchronous motor by counting pulses from an encoder 3 which detects the position of the rotor of the motor, reads out the sinusoidal wave signal corresponding to the position of the magnetic pole from the memory of a computer which controls the motor, inputs a three-phase voltage command obtained by multiplying the sinusoidal wave signal signal by the speed detecting 6 of the motor obtained by counting the pulses from the encoder 3 to a PWM circuit 9, detects the phase lag of the current of the motor at the point of time at which origin signals which are outputted from the encoder 3 at the switching point at every rotation of the motor are outputted, and corrects the sinusoidal wave signal data corresponding to the position of the magnetic pole of the motor stored in the memory of the computer in the direction in which the phase lag is reduced to zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic phase correction circuit for a synchronous motor used when controlling the rotation of the motor by passing a current in the same phase as the magnetic pole of the motor through the stator winding of the synchronous motor.

[0002]

2. Description of the Related Art In a synchronous motor, when the magnitude of the magnetic field of the field pole is φ, the current value is I, and the phase difference between the electric signal representing the true field pole position and the stator current is δ, the generated torque T is T = K · φ · Icosδ (K: constant). Therefore, when the phase difference δ becomes large, the generated torque becomes small. In other words, when controlling the motor with computer software, it takes time to detect the field pole and output a drive signal to the inverter, and during that time, the motor rotates and the position of the field pole changes moment by moment. Since the phase difference δ is further increased due to the change, the motor torque is reduced and the efficiency is deteriorated. As a means for correcting this phase difference δ, in the case of a synchronous motor, the phase difference between the induced voltage and the field pole position detection signal is detected by a counter,
A means for correction by microcomputer processing is proposed in Japanese Patent Application No. 58-158841. However, this means requires a detection circuit for the induced voltage and a phase difference detection circuit for the induced voltage and the field pole position detection signal, which not only complicates the circuit configuration, but in this case, occurs when the detector is attached. Although it is possible to correct the phase difference between the field pole and the detector due to mechanical deviation, the control amount (current) and the detection amount based on the delay caused by the software operation of the servo system and the delay caused by the detection method can be detected. The phase difference with the signal cannot be corrected. Further, there is a field pole detection position correction means for a synchronous motor which does not require detection of an induced voltage for detecting a field pole position and has a simple circuit configuration.
No. 148394. 4 to 6, 10 is a power conversion inverter for driving a motor, 11 is a synchronous motor of a motor, 12 is a resolver for detecting a field pole position, and 13 is a resolver position for detecting a resolver position. Detection circuit, 1
4 is a signal processing circuit for outputting a sine wave signal from the phase difference, 1
Reference numeral 5 is a resolver excitation circuit, 16a and 16b are multipliers for multiplying the torque command T by α-phase and β-phase outputs, 17 is a current control circuit for outputting a three-phase armature current command, and 18 is a drive signal group for the inverter 10. A pulse width modulation / drive circuit for outputting, a speed amplifier for outputting a torque command T by a speed deviation, a torque disturbance generating circuit for outputting a torque disturbance signal ΔT, a speed detecting circuit for calculating speed feedback, and a reference numeral 22 for It is a magnetic pole position error detection circuit that outputs a phase variable signal to the signal processing circuit 14 so that the generated torque becomes zero. In such a circuit, control is performed in the following steps as shown in the flowchart of FIG. Step 1: The speed command Nref is set to zero. Step 2: The torque disturbance generation circuit 20 generates the torque disturbance generation signal ΔT. Step 3: The speed detection circuit 21 calculates the speed Ntb. Step 4: Torque generated by speed amplifier 19 TK (Nre
f-Ntb) is calculated. Step 5: Determine whether the generated torque T is zero. Step 6: Determine the polarity of the generated torque T. This is the phase difference δ when the generated torque T becomes zero as described above.
To check if is π / 2 or 3π / 2. Step 7: A correction amount θc of the phase difference δ for performing vector control when the generated torque T is positive is set. Step 8: Set a correction amount θc of the phase difference δ for performing vector control when the generated torque T is negative. Step 9: The address of the ROM in the signal processing circuit 14 is incremented by "1", and the process returns to step 2. The processing from step 2 to step 3 is repeated until the generated torque T becomes zero. Step 10: The true magnetic pole position θ = δo + γ + θc is calculated. That is, δo + γ is calculated in this step, and the value of γ is stored in the signal processing circuit 14. When the synchronous motor 11 is driven, the torque disturbance generation circuit 20 and the magnetic pole position error detection circuit 22 are disconnected, γ stored in the input δo from the resolver position detection circuit 13 is added, and δ = δo + γ + θc is signal processed. Outputs sin θ, co calculated by the circuit 14 so that cos δ = 1
The signal processing circuit 14 outputs sθ. That is, the correction at this time is obtained by subtracting the ROM value of the address (δo + γ) from the output of the resolver position detection circuit 13 or the phase π / 2.
This is done by adding the value of the address corresponding to. This correction is performed every time the sine and cosine waveforms are generated. This simplifies the circuit structure by eliminating the detection circuit for the induced voltage for field pole position detection, and has high detection sensitivity because it detects the field pole position error at the output of the speed amplifier.
It is possible to correct the field pole position detection with high accuracy.

[0003]

However, in such means, the phase correction can be performed only when the line is off-line, so that the phase difference between the control amount (current) and the detection signal due to the calculation delay in the online mode is corrected. There is a drawback that you cannot do it.

The present invention has been proposed in view of the above circumstances, and has a simple structure and a highly accurate and economical motor capable of detecting and adjusting the phases of the field magnetic pole detection signal and the inverter drive signal online. An object of the present invention is to provide an automatic current phase correction circuit.

[0005]

To this end, the present invention provides 3
It is a synchronous motor driven by an inverter that generates a desired frequency output after converting the phase alternating current into a direct current, and a pulse train signal driven in synchronization with the synchronous motor and a magnetic pole switching point for each rotation of the synchronous motor. An encoder that outputs an origin signal, a magnetic pole phase detection circuit that inputs the above signals output by the encoder, and outputs this as a count value, a speed detection circuit that calculates speed based on the count value, and a magnetic pole phase detection circuit Output by ROM
A sine wave generation circuit for outputting a sine wave signal read from the speed control circuit, a speed control circuit for generating a torque command signal from the output of the speed detection circuit and the speed command signal Wref, an output iref of the speed control circuit and the sine wave A multiplier for multiplying the U-phase and V-phase sine wave magnetic pole positions output from the wave generation circuit, and the armature current commands Uiref and Viref, respectively, are input, and the U-phase current iu and V-phase current output from the inverter are input. iv is fed back to generate a three-phase voltage command, and a current control circuit and a current control circuit
And a PWM circuit for inputting a phase voltage command and driving an inverter to drive the synchronous motor.

[0006]

According to this structure, the motor is rotated by the inverter control via the PWM circuit by the sine wave signal output from the computer based on the torque command. When the motor rotates, the magnetic pole position of the motor is detected by the pulse count from the encoder that detects the rotor position, and the sine wave signal corresponding to the magnetic pole position is read from the memory of the computer that controls the motor. As a result, this sine wave signal is multiplied by the motor speed detection signal obtained by counting the pulses from the encoder, and the three-phase voltage command corresponding to the torque command is input to the PWM circuit, and the PW
By controlling the inverter by the output from the M circuit, a current in the same phase as the magnetic pole of the motor can be passed through the stator winding of the motor. Here, the origin signal is generated from the encoder at each magnetic pole switching point for each rotation of the motor, and the phase shift of the motor current is detected at the time of this magnetic pole switching. At the time when this phase shift is detected, the sine wave signal data corresponding to the magnetic pole position stored in the computer is corrected in the direction to make this phase shift zero. As a result, the motor is automatically phase-corrected every time the origin signal is generated so that the phase difference between the field pole position and the motor current becomes zero.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall circuit diagram thereof, and FIG. 2 is a magnetic pole waveform and motor winding current waveform diagram showing the principle of phase correction in FIG. FIG. 3 is a flowchart of the automatic phase correction in FIG.

First, in FIG. 1, an inverter 1 for converting a three-phase alternating current into a direct current and then generating an arbitrary frequency output.
The rotor position and speed of the motor 2 driven and controlled by the motor 3 are the pulse output from the encoder 3 linked to the motor and the origin signal from the encoder 3 output at the magnetic pole switching point for each rotation of the motor 2. Detected by. That is, the pulse train and the origin signal from the encoder 3 are input to the magnetic pole position detection circuit 4 and then output to the sine wave generation circuit 5 as a count value, and also input to the speed detection circuit 6. A sine wave signal is read from the memory (ROM) according to the count value from the sine wave generation circuit 5, and the torque command signal iref and the U phase from the sine wave generation circuit 5 are detected.
The V-phase output is multiplied by the multiplication circuits 7a and 7b,
The armature current commands Uiref and Viref are input to the current control circuit 8, and a three-phase voltage command is output from the current control circuit 8 to the PWM circuit 9 to cause the motor 2 to perform PWM.
The drive is controlled according to the waveform. The speed output from the speed detection circuit 6 is input to the speed control circuit 10 to feedback control the speed of the motor 2 so as to follow the speed command.

In such a control circuit, in the case of the automatic phase correction method of the motor current, the PWM circuit 9 by the sine wave signal output from the computer based on the torque command.
The motor 2 is rotated by the inverter control via. When the motor 2 rotates, the magnetic pole position of the motor 2 is detected by the pulse count from the encoder 3 that detects the rotor position, and the sine wave signal corresponding to the magnetic pole position is output from the memory of the computer that controls the motor 2. Read out. As a result, this sine wave signal and the torque command signal I which is the output of the speed control circuit 10
The three-phase voltage command calculated by the current control circuit 8 by the armature current command for each phase and the detected current is input to the PWM circuit 9 while being multiplied by ref, and the motor is controlled by the inverter controlled by the output from the PWM circuit 9. A current in the same phase as the magnetic poles of the motor 2 can be passed through the stator winding of No.2.

Here, the encoder 3 generates an origin signal at each magnetic pole switching point for each rotation of the motor 2, that is, at the zero point in FIG. 2, and at the magnetic pole switching point, the phase shift of the motor current, δ in FIG. Is detected. At the time when this phase shift is detected, the sine wave signal data corresponding to the magnetic pole position stored in the computer is corrected in the direction to make this phase shift zero, and the motor 2 is thereby able to generate the origin signal. Each time, automatic phase correction is performed so that the phase difference δ between the field pole position and the motor current becomes zero.

At this time, as shown in FIG. 3, in step 1, the count value from the encoder 3 is read, and in step 2, the speed count value and the processing time are multiplied to calculate a correction value, and then in step 3. It is determined whether or not the Z phase, that is, the origin position. If it is not the Z phase, the read address is obtained from the counter value + correction value in step 4, and the U phase from the address is determined in step 5
The V-phase sine wave signal is read out, and the motor 2 has a phase difference δ
The drive is controlled in a state in which is corrected to zero.
In the case of the Z phase, if iu = 0 or not in step 6 is 0, the phase difference δ is zero, so the motor 2 is controlled by steps 4 and 5 with the previous correction value. First, in step 6, it is determined whether iu> 0, and i
If u> 0, since the current is advancing, the read address is obtained from the counter value + (previous correction value -1) in step 4 while the correction value is -1 in step 8 and step 5 And the U phase from that address,
The V-phase sine wave signal is read out, and the motor 2 has a phase difference δ
The drive is controlled in a state in which is corrected to zero.
Next, in step 6, it is determined whether or not iu> 0, and iu>
If it is not 0, the current is delayed, so that the correction value is incremented by 1 in step 9, the read address is obtained from the counter value + (previous correction value +1) in step 4, and the address is determined in step 5. U phase from
The V-phase sine wave signal is read out, and the motor 2 has a phase difference δ
The drive is controlled in a state in which is corrected to zero.

[0012]

As a result, according to the present invention, the correction Σ of the phase difference between the current and the magnetic pole generated during the motor operation can be configured by a simple circuit, and the motor current is detected during the actual motor operation. Therefore, there is an effect that high-precision correction can be performed.

In short, according to the present invention, a synchronous motor driven by an inverter that converts a three-phase alternating current into a direct current and then generates a desired frequency output, and a pulse train signal that is driven in synchronization with the synchronous motor An encoder that outputs an origin signal, which is a magnetic pole switching point for each revolution of the electric motor, and a magnetic pole phase detection circuit that inputs the above signals output from the encoder and outputs them as count values, and speed calculation by the count values A speed detection circuit to perform, a sine wave generation circuit that outputs a sine wave signal read from the ROM by the output of the magnetic pole phase detection circuit, and a torque command signal based on the output of the speed detection circuit and the speed command signal Wref. Speed control circuit, output iref of the speed control circuit and U phase, V output from the sine wave generation circuit
Multipliers for multiplying the sine wave magnetic pole positions of the respective phases, and the armature current commands Uiref and Viref, respectively, are input, and the U-phase current iu, output from the inverter,
A current control circuit for feeding back the V-phase current iv to generate a three-phase voltage command; and a PWM circuit for inputting a three-phase voltage command from the current control circuit and driving the inverter to drive the synchronous motor To detect the phase of the field pole detection signal and the inverter drive signal online,
The present invention is extremely useful industrially because it has a structure that can be adjusted and has a simple and highly accurate and economical automatic phase correction circuit for the motor current.

[Brief description of drawings]

FIG. 1 is an overall control circuit diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram of a magnetic pole waveform and a motor winding current showing the principle of phase correction in FIG.

FIG. 3 is a flowchart of automatic phase correction in FIG.

FIG. 4 is an overall control circuit diagram showing a conventional motor current automatic phase correction method.

5 is a waveform diagram of a magnetic pole waveform and a stator current showing the principle of phase correction in FIG.

FIG. 6 is a flowchart of phase correction in FIG.

[Explanation of symbols]

 1 Inverter 2 Motor 3 Encoder 4 Magnetic pole position detection circuit 5 Sine wave generation circuit 6 Speed detection circuit 7a Multiplication circuit 7b Multiplication circuit 8 Current control circuit 9 PWM circuit 10 Speed control circuit

Claims (1)

[Claims] 1. A synchronous motor driven by an inverter that converts a three-phase alternating current into a direct current and then generates a required frequency output, and a pulse train signal driven in synchronization with the synchronous motor and each revolution of the synchronous motor. An encoder that outputs an origin signal that is a magnetic pole switching point of, a magnetic pole phase detection circuit that inputs the above signals output by the encoder and outputs the signals as count values, and a speed detection circuit that calculates the speed based on the count values. A sine wave generation circuit that outputs a sine wave signal read from the ROM by the output of the magnetic pole phase detection circuit; and a speed control circuit that generates a torque command signal based on the output of the speed detection circuit and the speed command signal Wref. A multiplier for multiplying the output iref of the speed control circuit by the U-phase and V-phase sine wave magnetic pole positions output by the sine wave generation circuit. And the armature current command Uiref, V
iref is input, and the U-phase current iu and V-phase current iv output from the inverter are fed back to generate a three-phase voltage command, and a three-phase voltage command is input from the current control circuit. And a PWM circuit for driving the synchronous motor by driving an inverter, the automatic phase correction circuit for the synchronous motor.