The Position-sensorless Control of Low Voltage High Power Permanent Magnet Synchronous Motors in Zero/Low-speed Regions

The traditional maximum torque per ampere (MTPA) control and the position-sensorless control based on the extended electromotive force (EEMF) with f-axis signal injection in zero/low-speed regions become difficult for low voltage high power permanent magnet synchronous motors (PMSMs), of which dq-axis inductances are susceptible to operating conditions. Taking full account of the motor particularity, it is pointed out in this paper that the dramatic changes in dq-axis inductances will lead to the incorrect orientation of maximum torque reference frame (f-t reference frame) and the failure of MTPA control. Thereby, the EEMF will be inadequate for the position-sensorless control. For the disadvantages of the prior methods, a novel position-sensorless control of low voltage high power PMSMs in zero/low-speed regions is proposed in this paper. By dealing with current control and position observation in different reference frames separately, the MTPA control and the position-sensorless control are well realized. The simulation based on JMAG model verifies the feasibility of the new proposal.