Method to detect the initial rotor position of PMSM based on current synthesis

The detection of initial rotor position is an important technology to ensure the successful launch of permanent magret synchronous motor (PMSM). When starting, it is necessary to accurately obtain the initial position of the rotor in the static state, otherwise it may lead to problems such as reverse rotation, excessive current, and even failure to start. The method of sensorless detection has the advantage of low cost, so it has been widely studied. Due to the magnetic flux saturation of the magnetic material, main flux of rotor at different positions affected the flux saturation of stator winding, resulting in the change of stator inductance and current. By injecting the basic space voltage vector with reciprocal directions into the PMSM stator winding, it stimulated the three-phase currents containing rotor position information. After detecting the peak currents, current synthesis was conducted. It proves that the synthetic results conform to three-phase sine law with the change of rotor positions, and the initial rotor positions under static state are observed. The errors between observed positions and actual positions are small. The algorithm is easy to calculate and has great value in application. © 2020, Harbin University of Science and Technology Publication. All right reserved.