General Switch Short-Circuit Fault-Tolerant Strategy of Active Magnetic Bearing Power Electronics Drive

In active magnetic bearing (AMB) system, the demand for reliability has been increasing, especially in high-speed applications. Failure of power electronics devices is one of primary challenges to the reliability. Among them, short-circuit is a typical failure that can lead to sustained overcurrent in the system, posing a severe threat to system stability. However, very few studies have been conducted on switch short-circuit fault-tolerant control in AMB system. Facing this problem, a general fault-tolerant strategy facing switch short-circuit is introduced in this article. Once the short-circuit happens, the corresponding winding is controlled with constant current mode, and the opposite winding is used to undertake dynamic response. The proposed method includes short-circuit failure detection, changes of relationship between leg and winding voltage in modulation, and proper fault-tolerant control based on force equivalence. Fault-tolerant control experiments show the effectiveness of the proposed approach. This approach provides high reliability for AMB system which will keep the rotor stable suspension even with power electronics devices short-circuit failure.