基于占空比调制的新型十八扇区直接转矩研究

New Eighteen-Sector Direct Torque Control Based on Duty Ratio Modulation

传统永磁同步电机直接转矩控制稳态运行时,存在定子磁链幅值和电磁转矩脉动较大的问题。分析了有效电压矢量对于定子磁链和转矩控制效果的不平衡问题,基于扇区细分的思想,并结合三电平逆变器新增的6个有效电压矢量,提出了新型十八扇区直接转矩控制方法,以此来改善电压矢量的控制效果。针对传统直接转矩控制中,由于整个采样周期施加同一电压矢量而带来的过补偿问题,采用占空比调制减小转矩脉动。与传统直接转矩控制效果进行仿真对比,验证了所提新型控制策略减小定子磁链和电磁转矩波动的有效性。

In the traditional direct torque control(DTC)of permanent magnet synchronous motor(PMSM)in steady state operation,the ripple of stator flux linkage amplitude and electromagnetic torque is large.In this paper,the unbalance problem of the effect of active voltage vectors on stator flux linkage and torque control is analyzed.Based on the idea of sector subdivision,combined with the six new active voltage vectors added by the three-level inverter,a new eighteen-sector direct torque control method is proposed to improve the control effect of voltage vectors.For the overcompensation problem caused by the voltage vector acting on a whole sampling period in DTC,the duty ratio modulation(DRM)method is used to reduce the torque ripple.Compared with the control effect of traditional direct torque,the effectiveness of the proposed new control strategy to reduce the ripple of stator flux linkage and electromagnetic torque is verified.