并联三相逆变器环流的双变零矢量控制研究

摘要

并联三相逆变器的参数不可避免地存在差异,导致逆变器间会产生环流.环流会造成逆变器损耗增加、输出电压、电流波形畸变等危害.为了解决这个问题,提出通过零序占空比来抑制环流的控制策略.在建立零序环流数学模型的基础上,针对传统零序环流控制策略中基于空间矢量脉宽调制(SVPWM)算法中一个载波周期内仅单次调节零矢量的作用时间,导致环流抑制效果不佳的问题,提出在一个载波周期内进行两次零矢量作用时间调节,提高零序环流控制实时性;并基于各逆变器输出的瞬时功率反馈来实现并联逆变器负载功率自适应均分的控制方案.该方案不仅能够很好地抑制环流,实现负载均分,而且能显著地改善三相逆变器输出电压和电流波形.通过仿真和半实物仿真实验平台验证了该方案的有效性.%Parameters of parallel three-phase inverters are inevitably different, which causes circulation current among inverters. Circulation current will increase energy loss, distortion of output voltage and current waveform, etc. In order to solve these problems, this paper proposes a control strategy that depresses circulation current by controlling zero sequence duty ratio. In SVPWM-based algorithm of traditional zero-sequence circulation control strategy, it only regulates the operating time once in a carrier cycle, resulting in poor circulation suppressing results. To solve the problem and on the basis of establishing zero-sequence circulated mathematical model, this paper proposes to carry out zero vector operating time twice in a carrier cycle to improve zero-sequence circulation suppressing real-timely, and realize the control scheme of shunt inverter load power adaptive sharing based on the instantaneous power feedback output by each inverter. The method can not only suppress circulation current, realize load sharing, but also can significantly improve output voltage and current waveform of three-phase inverters. The validity of the proposed method is verified by simulation and the semi-physical simulation experiment platform.