单周期控制三相PWM整流器在不对称电网下的研究

Study on Three-phase PWM Rectifier with One-cycle Control in Unbalanced Systems

传统的矢量模式单周期控制三相PWM整流器是基于对称电网系统下研究的,功率因数约为1,输入谐波低,且与双极型单周期控制相比,具有更低的开关损耗。当三相电网不对称时,三相输入电流跟踪电网电压的非零序分量,采用传统电网电压选择矢量区间不能保证三相PWM整流器具有较低的开关损耗,且在电网极端缺相故障时,系统不能正常工作。本文采用电网电压非零序分量选择矢量区间,并对矢量区间状态进行分析比较,结果证明所采取的方法能保证系统在任何情况下开关损耗最低。最后对三相PWM整流器工作于不对称电网情况下进行了仿真研究,仿真结果表明采用电网电压非零序分量选择矢量区间能保证电网电压在缺相故障时系统仍能正常工作,并且所采用的单周期控制同时满足对称电网系统。

Research on three-phase PWM rectifier based on traditional vector model one-cycle control （OCC） is in balanced systems, which achieves unity power factor and low THD. And compared with bipolar mode one-cycle control, vector model one-cycle control has minimum switching losses. In unbalanced systems, three-phase input current track the non-zero sequence phase voltages. Selection region based on voltages can＇ t ensure minimum switching losses and handle the extreme unbalanced system where one phase voltage is entirely zero. This paper employs the non-zero sequence phase voltages for region selection, and analyses vector region states, as a result, analysis verify the proposed OCC vector controller can ensure minimum switching losses in the any case. Finally, the simulation results show OCC controller with the non-zero sequence phase voltages for region selection ensure the system reliably work under extreme unbalance conditions, and also satisfy the balanced systems.