并联变流器的脉宽调制波重构与环流抑制
Reconstruction of Pulse Width Modulation Wave and Suppression of Circulating Current for Paralleled Converters
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摘要: 针对共交流滤波电感和直流母线的三相变流器并联时功率器件开关不同引起的环流问题,提出一种基于脉宽调制波重构的方法来抑制变流器并联时的零序环流。该方法采用主从控制,主控制器通过广播通信的方式将脉宽调制波参数和载波同步信号编码发送给从控制器,在满足采样时钟周期的约束条件下,从控制器根据通过解码载波同步信号和脉宽调制波参数重构出同步性良好的脉宽调制信号,从而达到减少零序环流的目的;并通过分析系统传递函数,研究通信延时对系统稳定性的影响,确定临界稳态通信延迟时间。最后,搭建了并联变流器实验系统,实验结果表明,所提控制策略能够减少零序环流。Abstract: For the circulating current induced by the three-phase converter modules in parallel system which share DC bus and AC filter inductor,a control strategy based on the reconstruction of pulse width modulation wave to inhibit the circulating current is proposed.With this strategy,the master-slave control sends the information in the form of parameters and synchronous signal to the subordinate controller via broadcast communication.Good synchronization pulse width modulation signal is reconstructed by decoding the carrier synchronization signal and pulse width modulation wave parameters on the slave controller under the sampling clock cycle constraints.The consistent pulse width modulated signal is reconstructed by each subordinate controller to achieve the purpose of reducing circulating current.And the effect of communication delay in system stability is studied by analyzing the transfer function of the system.The communication delay time of critical stability is determined.A parallel converter experimental system is built.Experiment results verify that the proposed control strategy can reduce the circulating current.
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