五相永磁同步电机磁链改进型容错直接转矩控制

Flux-modification-based Fault-tolerant DTC for Five-phase PMSM

针对五相永磁同步电机驱动系统中开路故障导致转矩脉动大且动态性能差的问题,提出一种磁链改进型容错直接转矩控制策略。该策略基于故障前后磁动势不变原则,推导故障状态下的推广克拉克(Clarke)变换矩阵,建立五相永磁同步电机故障时的数学模型。在此基础上,设计一个系数修正定子磁链,使其与正常运行时一致。根据铜损最小原则,优化定子容错电流,同时采用基于零序电压谐波注入式脉宽调制技术,实现了电机转矩和定子磁链的准确控制。实验结果表明,该容错DTC策略能提高电机开路故障情况下转矩的稳态和动态性能,实现五相永磁同步电机的无扰运行。

To solve the torque fluctuations and deteriorated dynamic performance resulted from open-circuit fault, a fault-tolerant direct torque control(DTC) strategy based on modified stator flux was proposed for five-phase permanent magnet synchronous motor(PMSM) in this paper. Firstly, an extended Clarke transformation matrix was derived according to the constant rotating magnetic motive forces(MMFs) both in healthy and fault operations, and then the mathematical model of five-phase PMSM with fault was built. On this basis, a coefficient was introduced to modify stator flux. Secondly, the fault-tolerant currents were optimized according to the minimum copper loss criterion. Meanwhile, the zero-sequence voltage harmonic injection of carrier-based pulse width modulation was adopted in the fault-tolerant DTC strategy to achieve the accurate control of torque and stator flux. The experimental results demonstrate that the fault-tolerant DTC strategy can offer good steady-state and dynamic performance, and achieve the disturbance free operation.