Sensorless IPMSM based drive for reciprocating compressor

This paper presents a new algorithm for the position sensorless vector control of the Interior Permanent Magnets Synchronous Motors (IPMSM), which is based on the well-known approach for the Permanent Magnets Synchronous Motors (PMSM), when rotor position and speed information is obtained by using current error between actual and estimated currents. Estimated current is calculated using motor model, which is written in the synchronous reference frame dq. The current difference is decomposed into two components. One of them is used for the motor back-emf and speed estimation and another one is used as a correction term. Rotor position is calculated as an integral of the estimated speed. Utilization of two current error components allows to build reliable system with low estimation error, where one current error component is used for estimation in static modes and another one is used for estimation in dynamic mode. This paper shows that sensorless algorithm for the PMSM can be spread also on the IPMSM and it works perfectly even under the difficult load conditions such as reciprocating compressor. Robustness of the proposed algorithm and its sensitivity to the motor parameters variations are also described. This paper also pays attention to the drive starting procedure in the sensorless mode.