High-Dynamic and Low-Cost Sensorless Control Method of High-Speed Brushless DC Motor

Sensorless control is an effective measure to improve reliability and reduce cost for the brushless dc motor (BLDCM). However, the performance is generally related to the cost and complexity of the system, making it difficult for engineering applications. Therefore, this article proposes a high-dynamic and low-cost sensorless control method for high-speed BLDCMs using the rich built-in resources of the digital signal processor. First, a variable relating to the commutation moment is constructed and detected, which is not affected by modulation noise. Then, a detailed commutation process is presented based on the relationship between the back electromotive force (back-EMF) integral and the commutation point. Moreover, an integral prediction method is proposed by linearizing the back-EMF to cope with the effect of discrete sampling on commutation accuracy. Finally, experimental tests are performed on a magnetically suspended control moment gyroscope, which verifies the effectiveness of the proposed high-dynamic and low-cost sensorless control method.