提高异步电机调速系统的可靠性和EMC性能的研究

本文提出了一种应用于异步电机调速系统的基于三相四桥臂结构的逆变策略，它既改
善了系统的EMC 性能又提高了其可靠性。在这个策略中，如果系统正常工作，第四桥臂可以平衡逆变器的输出电压，从而降低系统的共模电压。在这个过程中使用本文提出的状态交换策略不仅突破了以往SPWM 调制指数必须在0.66 以下的限定，避免了直流电压利用率低下的问题，而且优化了系统的差模输出，将总的谐波失真度降到最低。如果系统的一个逆变桥发生故障，第四桥臂可以作为冗余桥臂代替故障桥臂的工作。采用暂时开环控制可以是桥臂切换平稳，降低切换过程中出现的过冲电流。这样系统可以不间断地容错运行，整体的可靠性得到显著改善。该策略的有效性通过仿真和实验得到了证实。
Abstract：This paper proposes a strategy based on three-phase four-leg structure that can improve either reliability or EMC performance in speed regulating system of asynchronous motor. In the strategy, if the system is working orderly, the fourth leg functions in balancing the output voltage so as to reduce the common mode (CM) voltage of the system. During this process, the use of state exchange method not only breaks through the limitation of SPWM modulation index to avoid the extremely low utilization ratio of direct current (DC) voltage, but also reduces the total harmonic distortion factor (THD) of the output voltage. If an inverter leg of system is in failure, the fourth leg acts as the redundant leg to take the place of that one. The transitory open-loop control is adopted to reduce the overshoot current and to switch leg smoothly. Thus the system can run uninterruptedly in the fault tolerant operation mode and the holistic reliability can be improved markedly. The effectiveness of the strategy is proved by simulation and experiment results.
关键词：三相四桥臂，可靠性，共模电压，容错运行，策略
Keyword：Three-phase four-leg, reliability, common mode voltage, fault tolerant operation,
strategy