Short-Circuit Fault-Tolerant Strategy for AMB Power Electronic Controller Based on Shared-Bridge Topology

Short-circuit faults of power electronics devices are major reason for active magnetic bearing (AMB)system failures, posing a serious threat to system stability, especially during high-speed rotor rotation. Despite this, very few studies have explored switch short-circuit fault-tolerance in AMB system. To address this issue, this paper introduces a fault-tolerant control strategy for short-circuit faults in switching devices, based on shared-bridge topologies. Two set of shared-circuit topologies are used separately to control one coil of each axis, once the short circuit happens, the coils controlled by the faulty shared-bridge topology are controlled to constant current, while the coil controlled by the normal shared-bridge topology are controlled to bias current and control current. In addition, the current must to be reversed to ensure the controllability of the faulty shared-bridge topology. The method also includes short-circuit fault detection. Relevant fault-tolerant experiments have been done to verify the effectiveness of the proposed approach. This approach provides high reliability for AMB system even with the power electronics devices short circuit failure.