Start method for PMSM without position sensor in rotating conditions
JIANG Zhen jun, ZHANG Wei
(College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China)

Abstract: Aiming at the matter that permanent magnet synchronous machine (PMSM) with no position sensor cannot start reliably in rotating conditions, two zero vectors were applied to inverter to make three phase stator windings of the machine had a short circuit. Through analyzing the angle variation of the currents in αβ coordinates, the rotational direction and speed of the machine were derived. Furthermore, through analyzing the transient state process of the currents in dq coordinates, the rotor position of the machine was estimated, the relationship between the initial speed, the duration of short circuit and the amplitude of short circuit current was put out, a start method for PMSM in rotating conditions was offered specifically. The start method mentioned above was evaluated on the experimental platform, which TMS320F28027 provided by TI was used as the master of the whole control system, and a fan was used as the load of PMSM, whose rated power is 550W, the start method was tested under different initial speed and duration of short circuit conditions. The experimental results show that according to short circuit currents, the start method designed, can estimate the rotation direction, initial speed and rotor position precisely, thus reliable start of PMSM in rotating conditions can be achieved.

Key words: without position sensor; permanent magnet synchronous machine(PMSM); start in rotating conditions