Performance-guaranteed open-circuit fault-tolerant strategy for dual-winding steer-by-wire system

Abstract

Compared with the dual-motor steer-by-wire system, the emerging dual-winding steer-by-wire system shows promising applications by eliminating synchronization control challenges, reducing configuration costs, and employing straightforward fault-tolerant mechanisms. To improve motor control performance under open-circuit faults, this paper proposes a performance-guaranteed fault-tolerant strategy. This strategy initially triggers passive fault-tolerant control through fault detection, improving the fault response speed to the millisecond level, thus allowing the system to tolerate delays in fault identification. The error-proof processor, along with the adaptive threshold, enhances fault detection capabilities under no-load and light-load conditions. In addition, the modified average phase current method obviates the need for threshold-based aids while increasing the security margin of fault identification. Moreover, the active fault-tolerant control, which is based on xy subspace current injection, is extended to address single open-switch faults. By leveraging the full potential of all remaining healthy drives, the adopted active fault-tolerant control increases the torque output capability by approximately 10.9% for single-phase faults and 37.2% for single open-switch faults, respectively, while reducing copper loss by around 25% and 37.5%, respectively. This demonstrates substantial benefits compared to the three-phase scheme that completely isolates faulty windings. Finally, simulation and experimental results confirm the excellent post-fault performance of the proposed strategy under both steady-state and transient operating conditions.