Control device for a synchronous motor
AssigneeKabushiki Kaisha Yaskawa Denki Seisakusho
InventorsTakanobu Iwakane, Tohru Kai, Kenji Hirose, Koichiro Nakagawa
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Abstract
In a control device of an AC motor wherein a torque equivalent to that of a DC motor is created by controlling the instantaneous values of its stator current, or in a vector control device, signals from a position detector such as a resolver coupled to the AC motor are utilized to form stator current instruction signals and to provide rotation position feed-back signals and rotation speed feed-back signals for the AC motor, thereby to perform precise servo-control.
Claims1
A control device of a synchronous motor which carries out a vector control so that a torque equivalent to that of a shunt DC motor is generated by controlling the instantaneous value of a stator current in the synchronous motor, which comprises:
- a resolver coupled to said synchronous motor;
- a first frequency division circuit (15) for subjecting an output of a shaping circuit (13), said output being a rectangular wave signal which is of the same frequency as that of a detection signal of said resolver to 1/n frequency division;
- a second frequency division circuit (16) for subjecting an output of a shaping circuit (14), said output being a rectangular wave signal which is of the same frequency as that of an output of an exciting circuit (12) of said resolver to 1/n frequency division;
- a two-phase beat generator for receiving outputs of said first and second frequency division circuits (15 and 16), to output two-phase current instruction signals cos (.theta..sub.e /n) and sin (.theta..sub.e /n) whose phases are shifted by 90 degrees from each other;
- a frequency-to-voltage conversion circuit for subjecting a signal of said resolver to frequency-to-voltage conversion, to provide a speed feedback signal;
- a third frequency division circuit (23) for subjecting the signal of said resolver to frequency division, to provide a position signal;
- a phase comparison circuit for comparing the phase of a position instruction signal with the phase of said position signal;
- and
- first and second multipliers (7 and 8) in which said two two-phase current instruction signals are multiplied by a speed signal which is obtained by comparing an output of said phase comparison circuit with said speed feedback signal, respectively,
- outputs of said first and second multipliers being used as instruction signals for the stator current in said synchronous motor.
Dependencies are inferred from the claim text.