Short-Circuit Fault-Tolerant Topology and Control Strategy for Active Magnetic Bearing Drive Based on Shared Bridge Arm

In active magnetic bearing (AMB) systems, the demand for reliability is extremely high owing to their specialized applications. Power electronic converter is one of the primary sources of faults that lead to AMB systems. Nonetheless, there is presently little research dedicated to fault-tolerant strategies for switching devices, particularly for short-circuit faults. In this article, a short-circuit fault-tolerant shared-bridge converter topology and control strategy are presented. First, two types of electromagnetic coils that control a single AMB axis are divided into separate sets and controlled individually using a shared-bridge topology, which helps to distribute risk. Subsequently, a detailed analysis is conducted on the control performance of shared-bridge topology in faulty mode, which clarifies the rationality of current reversal and the converter's ability to control constant currents. Then, based on the characteristics of faulty topology, a method of fault detection and a novel current distribution strategy using the principle of electromagnetic force conservation are proposed. Finally, the fault-tolerant experimental results at both standstill and rotation verify the effectiveness of the fault-tolerant strategy.