Combination of voltage model and high-frequency signal injection for sensorless permanent magnet synchronous motor drives

The paper proposes a method for the rotor speed and position estimation of permanent magnet synchronous motors, applicable in a wide speed range including standstill. A modified voltage model is used at high speeds, and it is combined with a high-frequency signal injection technique at low speeds. The fast dynamic response of the voltage model is thus augmented with the steady-state accuracy of the high-frequency signal injection technique. The stability and robustness of the combined observer are demonstrated by simulations and experiments.