Signal Injection in Sensorless PMSM Drives Equipped With Inverter Output Filter

The paper proposes a hybrid observer for sensorless control of permanent magnet synchronous motor drives equipped with an inverter output LC filter. An adaptive full-order observer is augmented with a high-frequency signal injection method at low speeds. The only measured quantities are the inverter phase currents and the dc-link voltage. It is shown that the LC filter is not an obstacle to using signal injection methods. The proposed method allows sensorless operation in a wide speed range down to zero speed. Experimental results are given to confirm the effectiveness of the proposed method.