Method for encoderless field-oriented control of an asynchronous machine

摘要

A sensorless field-orientation control (2) for an induction motor (4) is disclosed. Estimated values ( phi S, omega m, R1) for an orientation angle ( phi S), a rotor speed of rotation ( omega m) and a stator resistance (R1) are calculated by means of an MRAS (8) used as a motor model. When the induction motor (4) is operated as a generator, the actual estimated value (R1) of the stator resistance (R1) when the generator mode starts is retained and the estimated value ( omega m) of the rotor speed of rotation ( omega m) at high speeds as well as in the mode of operation as a motor and at low speeds of rotation is calculated based on the mechanical motion equation with a constant estimated load moment (ML). A sensorless field-orientation control is thus achieved that allows an induction motor (4) to be controlled even when it is operated as a generator.