초록 ▼

An alternating-current motor is used as an actuator of a positioning control system. The control variable to control the torque of the motor is the load angle qd of a synchronous motor or the slip frequency fs of an induction motor. The highest and the lowest limit values of the control variable are

An alternating-current motor is used as an actuator of a positioning control system. The control variable to control the torque of the motor is the load angle qd of a synchronous motor or the slip frequency fs of an induction motor. The highest and the lowest limit values of the control variable are respectively predetermined from the characteristics between the torque and the control variable and from other design considerations. The preparatory value E for the control variable is synthesized in accordance with an equation E=G1(qc-qa)-G2pqa, where qc is the reference position, qa is the controlled position, G1 and G2 are respectively amplification constants, and p denotes the differential operator d/dt. When E is within the predetermined highest and the lowest limit values of the control variable, E is used as the control variable; when E is larger than the predetermined highest limit value, the highest limit value is used as the control variable; and when E is smaller than the predetermined lowest limit value, the lowest limit value is used as the control variable. After the control variable is thus determined, the instantaneous phase angle signal is synthesized in accordance with an equation qp=qa +qd or qp=qa +2 pfs/p where the instantaneous electrical angular position of the rotor of the motor is also denoted by qa. The instantaneous phase angle of the power supply to the motor is controlled with this synthesized qp as the reference signal. The voltage amplitude V1 of the power supply is controlled as a constrained variable to control the torque of the motor. The reference signal of the voltage amplitude V1 is determined as a function of the frequency of the power supply, or in one embodiment for a synchronous motor, as a function of the frequency and the load angle.

대표청구항 ▼

A control system of a polyphase alternating-current motor comprising: a polyphase alternating-current motor; power supply means for generating a polyphase alternating-current voltage to be supplied to said motor, the amplitude and the instantaneous phase angle of said alternating-current voltage bei

A control system of a polyphase alternating-current motor comprising: a polyphase alternating-current motor; power supply means for generating a polyphase alternating-current voltage to be supplied to said motor, the amplitude and the instantaneous phase angle of said alternating-current voltage being controllable; position detector means for detecting the instantaneous electrical angular position of the rotor of said motor with respect to a stator reference; means for producing an initial value for the control variaBle to control the torque generated by said motor; phase signal generator means for generating an instantaneous phase angle signal from said initial value for the control variable and said detected instantaneous electrical angular position of said rotor; phase angle control means for controlling said instantaneous phase angle of said alternating-current voltage with said generated instantaneous phase angle signal as the reference signal; voltage signal generator means for generating a voltage signal in accordance with a predetermined voltage control law; and voltage control means for controlling said amplitude of said alternating-current voltage with said generated voltage signal as the reference signal.