基于交错断续空间矢量调制的并联PWM变流器控制策略

Control Strategy for Parallel PWM Converters With Interleaved Discontinuous Space-Vector Modulation

并联PWM变流器可以显著增大变流器的容量并提高交流侧的电能质量,但是变流器的直接并联容易在其内部产生环流,从而导致变流器损耗增加甚至开关器件损坏。本文以三相PWM整流器并联系统为例给出了环流的数学模型,该环流是一个存在于零轴的带直流偏移量的环流。针对环流问题,本文通过建立并联系统的小信号模型分析确定了零序电流环的设计,并采用了交错断续空间矢量调制方法来消除和抑制其对整个系统的影响。通过该方法,环流可以用dq轴分量表示,并通过功率因数校正(PFC)电路的电流环加以抑制。最后的仿真和实验验证了本文控制策略的有效性。

Parallel PWM converter can significantly increase the capacity of the converter and improve the power quality of AC side, but the circulation which can lead to high switching loss and even damage the devices will easily exist in the direct parallel converters. In this paper, the circulation mathematical model of three-phase PWM rectifier parallel system is shown, and the circulation is a zero-axis circulating current with the DC offset. To address the circulation problem, a small signal model is established to analyze and determine the zero-sequence current loop, and the control strategy with interleaved discontinuous space-vector modulation （IDSVM） is used to eliminate and suppress the influences to entire system. Then the circulation can be described by dq axis components and inhibited through the power factor correction （PFC） circuit of the current loop. Finally, the effectiveness of control strategy is verified by the simulations and experiments in this paper.