高速动车组辅助变流器并联运行的脉宽调制技术

Pulse Width Modulation Technique for Paralleled Operation of Auxiliary Converter Units of High-speed EMU

脉宽调制技术是电力电子变换器中最底层的控制之一。高速动车组中的辅助变流器中,受变流器发热的限制,开关频率比较低。而且变流器输出正弦滤波器受制于体积和本身质重的限制,截止频率不能设计的太低。针对该不利因素,为了保证变流器输出三相交流电压的电源质量,文中提出了一种新改进的调制方法。在开关频率不变的前提下,采用非对称规则采样,并注入一定量的三次谐波,就能够消除大部分偶次谐波,降低其输出电压谐波含量。该方法在辅助变流器并联运行时,显著地抑制了谐波环流,成功地应用于高速动车组辅助变流器的控制。

The pulse width modulation （PWM） technique is one of the fundamental control techniques for power converters. The switching frequency of the EMU auxiliary converter unit （ACU） is usually very low due to the thermal limit. Meanwhile, the size and weight of the sinusoidal filter consisting of inductor and capacitor are also limited, so that the cut-off frequency cannot be designed to a consid- erably low. According to the drawbacks above, a new improved PWM technique is proposed to achieve better power quality at the low switching frequency without increasing the demand of the sinusoidal filer. This technique including asymmetric regular sampling method and third harmonic injection can reduce voltage harmonics effectively, eliminating most of even order harmonics. The experiment results show that this method is successfully applied to the ACUs, the sinusoidal voltage outputs are achieved and the harmonic circulating cur- rents are suppressed low at parallel operation.