基于五电平变换器的开关磁阻电动机转矩脉动抑制方法

Torque Ripple Reduction Method of Switched Reluctance Motor Based on Five-Level Converter

针对开关磁阻电动机(SRM)在换向时电流跟踪效果不佳造成的转矩脉动问题,提出一种基于五电平变换器的开关磁阻电动机转矩脉动抑制方法.设计一种A、C相或B、D相共用同一桥臂的新型五电平变换器结构,较传统变换器控制更灵活、成本更低.根据SRM的非线性模型重新划分导通区间,优先选择电感变化率较大的相输出转矩,避免换向初期电流峰值过大.针对转速及负载等工况发生较大变化时绕组电流跟踪能力不佳问题,提出基于五电平变换器的直接瞬时转矩控制(DITC)方法,设计低速与高速的DITC导通规则.根据当前转速、转矩误差以及转子位置选择适配的导通方式,实现电动机低速时能够稳定运行,高速时电流能及时跟踪所需电流值,实现转矩脉动的抑制.仿真和实验结果表明:相比于传统DITC,该控制策略能在宽速域下实现转矩与电流脉动的抑制,改善转矩的动态特性.

Aimed at the problem of large torque ripple and low efficiency caused by the poor current tracking effect of switched reluctance motor(SRM),a torque ripple reduction method of switched reluctance motor based on a five-level converter is proposed.A novel five-level converter with A and C phases or B and D phases sharing the same bridge arm is designed.Compared with the traditional converter,the control is more flexible and the cost is lower.According to the nonlinear model of SRM,the conduction region is reclassified,and the phase output torque with a large inductance change rate is preferred to avoid excessive peak current at the beginning of commutation.Aimed at the problem of poor winding current tracking ability when the speed and load conditions change greatly,the direct instantaneous torque control(DITC)method based on the five-level converter is proposed,and the DITC conduction rules at low and high speeds are designed.According to the current speed,the torque error,and the rotor position,the appropriate conduction mode is selected to make sure that the motor can run stably at a low speed and the current can track the required value in time at a high speed,so as to realize the reduction of torque ripple.The simulation and experimental results show that compared with the traditional DITC,the control strategy can reduce the torque and current ripple in a wide speed range and improve the dynamic characteristic of the torque.