Sensorless field orientation control method of an induction machine by high frequency signal injection

摘要

The present invention is related to the method to find the rotor flux angle from stator voltages and currents by injecting high frequency signal. The injected signal is not rotating one but fluctuating one at a reference frame rotating synchronously to the fundamental stator frequency. The difference of impedances between the flux axis and the quadrature axis at high frequency signal injected on the rotor flux angle is explained by the equivalent circuit equation of the induction machine. The difference is verified by experiments on the test motors at various conditions. The sensorless field orientation control method is proposed and experimental results clarify the satisfactory operation of the method with 150% load torque at zero stator frequency.