Improved initial pole-position estimation of SPMSM sensorless servo drive by absolute integrals of torque-component currents

In this paper, the initial pole-position estimation of a surface (non-salient) permanent magnet synchronous motor is analysed mathematically, and more accurately improved for SPMSM sensorless servo drive by the absolute accumulation (or integral) of torque-component currents. This algorithm is well carried out under the full closed loop position control without any pole sensors and is completely insensitive to any motor parameters. This estimation is based on the principle that the initial pole-position is simply calculated by the reverse trigonometric function using the two feedback currents in the full closed-loop position control. The proposed algorithm consists of the predefined reference position profile, the information of feedback currents, speed, and relative position, and the reverse trigonometric function for the initial-pole position estimation. Compared to other existing researches, the mathematical analysis is introduced to get the more accurate initial pole-position of a surface permanent magnet motor under the closed-loop position control. It is recognized that this algorithm is simpler in implementation and is more accurate in estimation even close to standstill through the full closed control.