考虑去磁效应的五相永磁同步电机优化开关表直接转矩控制算法

A Direct Torque Control Algorithm Considering the Demagnetization Effects for Five-phase Permanent-magnet Synchronous Machines Using Optimized Switching Table

多相永磁同步电机驱动系统因具有体积小、噪声低、功率密度高等诸多优点,在低压、大功率输出及可靠性要求高的场合已得到了广泛关注和应用。基于开关表的直接转矩控制(switching table direct torque control,ST-DTC)算法具有结构简单、转矩动态响应快、对电机参数依赖性低等优点,然而将其直接扩展应用于多相系统会造成较大的转矩脉动以及谐波电流。因此,该文在传统ST-DTC算法的基础上,首先将开关表中的电压矢量集重构为虚拟矢量集,用以消除定子电流的低次谐波,其次深入研究了电机中低速运转时由于定子电阻造成的去磁效应,并且重新设计了开关表用以克服该问题,保证了电机磁链的控制需求,最后根据电机的转矩脉动规律采用多阶非对称结构的滞环比较器,优化了转矩纹波。实验结果表明了所提算法的正确性和有效性。

The multi-phase permanent magnet synchronous machine （PMSM） has the property of small size, low noise and high power density, so it has been widely used in high power, low-voltage, and high reliability occasion. Direct torque control algorithm based on switching table （ST-DTC） has the advantages of simple structure, fast torque response, and independence on the machine parameters. However, when it comes to the multiphase PMSM, torque ripple and harmonic components in stator currents are inevitable due to the lack of controlling variables in the harmonic space. According to the analysis of traditional ST-DTC, a virtual voltage vector set solution, reconstructed by the voltage vector set in switching table, was proposed to reduce the low-order harmonic components of stator currents. Then, the demagnetization effect of stator flux caused by stator resister was analyzed when the motor runs in lower speed range. And a modified switching table was provided to overcome this drawback. Finally, on the basis of the torque fluctuation characteristic, an asymmetric multi-level torque hysteresis-loop regulator was proposed to reduce torque ripples. Experimental results show the validity and effectiveness of the proposed DTC scheme with asymmetric multi-level torque hysteresis- loop regulator and virtual voltage vector.