ANORDNING OCH FORFARANDE FOR ALSTRING AV SIGNALER PROPORTIONELLA MOT LIKSTROMSFLODET I EN VEXELSTROMSMOTOR

摘要

An apparatus and method for providing signals indicative of the magnitude and angular position of the DC motor flux of an AC induction motor is disclosed. The AC induction motor provides controllable rotation and torque in accordance with a drive current of variable magnitude and frequency. A first signal is provided proportional to the rate of change of the flux of the motor. A second signal is supplied proportional to the magnitude of the drive current. A flux signal is generated proportional to the integral of the first signal when the frequency of the output signal is above a preselected value and which is proportional to the second signal when the frequency of the output signal is below the preselected value. A representative value for the preselected frequency value is 3 Hertz in a 60 Hertz drive system. The flux signal is effective to control the generation of the drive current. An embodiment of the present invention is shown for the case where the motor is stopped at a predetermined position in accordance with a predetermined conduction state of the inverting supplying the drive current. Additional embodiments are shown for the general cases where the motor can be stopped at any position and where two flux axes or three flux axes are sensed. The present invention is particularly applicable for use in an AC induction motor drive system.