SVPWM中的开路零矢量及其对磁链轨迹的影响研究

Study of Open-circuit Zero Voltage Vector and its Effect on Flux Trajectory in SVPWM

提出了一种开路零电压矢量,以改善SVPWM(空间电压矢量脉宽调制)中传统短路零电压矢量引起的磁链幅值衰减快和电磁转矩波动大的缺点。在传统的8种开关模式的基础上拓展了4种新的有效开关模式,从而产生开路零电压矢量。经研究发现,传统的短路零电压矢量作用于电机时,电机处于能耗制动状态,磁链幅值衰减快,电磁转矩为负值;而开路零电压矢量作用时,电机处于自由停车状态,磁链幅值衰减速率较短路零电压矢量作用时慢大约1倍,电磁转矩为零,且与非零电压矢量切换时,电磁转矩波动小,转速也将更加平稳;并用PLECS软件对两种零矢量仿真,验证了分析结果。

Proposed an open-circuit zero voltage vector to improve the disadvantages caused by the short-circuitzero vectors in traditional SVPWM,such as fast flux amplitude attenuation and electromagnetic torque ripple. In order to generate open-circuit zero voltage vector,4 kinds of novel effective switch modes had been extended on the basis of 8 kinds of traditional switch modes. The research results show that when traditional short-circuit zero voltage vector acts on motor,it works in dynamic braking,the flux amplitude decayed rapidly and electromagnetic torque is negative;when open-circuit zero voltage vector acts on motor,it works in the state of free stopping,the decay rate of the flux amplitude is about twice as slowly as the state of short-circuit zero voltage vector. Compared with short-circuit zerovoltage vector,it has lower fluctuation of electromagnetic torque and the speed will be more smoothly when it switches to non-zero voltage vectors. Furthermore two kinds of zero voltage vectors were simulated by PLECS and analysis results is verified.