背靠背永磁直驱风电变流器共模电压抑制方法

Common-mode voltage suppression strategy for back-to-back permanent-magnet direct-drive wind power converters

针对常规的模型预测共模电压抑制方法需要设计权重因子、计算量大、开关频率高等问题,提出了一种改进的基于电压矢量优化的背靠背永磁直驱风电变流器共模电压抑制方法。详细分析了每个电压矢量对背靠背风电变流器电流变化率的影响,从而揭示了3矢量法存在电流畸变的本质原因,并基于该分析结果提出了一种改进的4矢量模型预测共模电压抑制方法。该方法不仅适用于机侧变流器,而且适用于网侧变流器。在实现共模电压抑制的同时,该方法还可以降低开关频率并减小计算量,且没有明显影响电流的动稳态特性。仿真和实验结果验证了所提方法的有效性。

Conventional model predictive common-mode voltage reduction methods need to design weighting factors and have problems of large calculation amount and high switching frequency.An improved voltage vector optimization based common-mode voltage suppression strategy is proposed for back-to-back permanent-magnet direct-drive wind power converters.The influence of each voltage vector on the current rate of the back-to-back wind converter was analyzed in detail,which reveals the essential reason of current distortion in the 3-vector method.Then,an improved 4-vector based common-mode voltage suppression strategy was proposed based on analytical results.This method can be applied not only to the generator side converter but also to the grid side converter.And this method can suppress the common-mode voltage,and at the same time reduce the switching frequency and the calculation amount with no obvious effect on the dynamic and steady state response of the current.Simulation and experimental results verify the effectiveness of the proposed algorithm.