Sensorless Vector Controlled Drive For Reciprocating Compressor

This paper presents a new algorithm for position sensorless vector control of the permanent magnets synchronous motors (PMSM), which is based on the well-known approach, 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 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 in dynamic mode. Robustness of the proposed algorithm and its sensitivity to the motor parameters variations are also described. This paper pays attention to the drive starting procedure in the sensorless mode as well.