Lucheng Sun

The high-performance control of permanent magnet synchronous motors hinges on precise rotor position information. However, traditional mechanical sensors are plagued by high costs, large dimensions, and low reliability. As a result, position sensorless control technology has emerged and is becoming a research hotspot in the field of motor control. This article comprehensively reviews the existing position sensorless control technologies for permanent magnet synchronous motors. First, the fundamental principles of classical methods based on the motor’s fundamental wave model and saliency effect are analyzed in detail. Second, the advantages, disadvantages, and applicable scenarios of various position sensorless control methods are summarized. Finally, the key issues that need to be addressed in future research are pointed out.

Power devices in series are low-voltage power devices used in medium- and high-voltage applications in a more direct program. However, when power devices in series are used, because of their electrical performance parameters or external circuit conditions, there are unique short-circuit voltage imbalances, a serious threat to the safety of the device. The article first summarizes the research status and characteristics of the four models of SiC MOSFETs based on the domestic and international research on the models of SiC MOSFETs in recent years; second, the voltage balancing technology of series-connected SiC MOSFETs is sorted out and summarized, and then the driving circuits of SiC MOSFETs are sorted out and summarized. Again, several voltage balancing techniques reviewed are compared in six different aspects: cost, modularity, complexity, speed of voltage balancing, losses, and effectiveness of voltage balancing. Finally, an outlook of voltage balancing techniques for series SiC MOSFETs is provided.