Controller Design of Sensorless Induction Machine by High Frequency Voltage Injection

Abstract

This paper describes a new sensorless induction motor drive scheme by injecting high frequency voltage signal. The signal is not a rotating one, but a fluctuating one at a synchronous rotating reference frame with the fundamental stator frequency. The difference of impedance between the flux axis and the quadrature axis at high frequency signal injection on the rotor flux angle is used to track the rotor flux angle. Since the injection signal is independent on the stator frequency, the monitoring of the differences of impedance can be done even at stand still condition of motor. Speed and current controller suitable for high frequency voltage injection are designed and verified by experiments.