Dong-Woo Seo, Yeongsu Bak, and Kyo-Beum Lee, "An Improved Rotating Restart Method for a Sensorless Permanent Magnet Synchronous Motor Drive System Using Repetitive Zero Voltage Vectors," IEEE Transactions on Industrial Electronics, vol. 67, no. 5, pp. 349 > Paper

This paper presents an improved rotating restart method for a sensorless permanent-magnet synchronous motor (PMSM) drive

system using repetitive zero voltage vectors. To restart the sensorless PMSM drive system, a method for estimating initial

rotor position and speed is required due to the absence of sensors such as encoders and resolvers. The rotor position and speed

can be estimated using the short-circuit current vectors generated by applying zero voltage vectors. However, the estimated rotor

position and speed can be inaccurate. The inaccurate rotor position causes the current is distorted by the back electromotive force

(EMF) of the PMSM and it is impossible to precisely control the system. Therefore, an improved rotating restart method for the

sensorless PMSM drive system using repetitive zero voltage vectors is proposed. The effectiveness of the proposed method is verified

through simulation and experimental results using a 5-kW PMSM drive system.