两种应用于机车牵引变换器的调制方法

Application of Two Kinds of Modulation Methods in Locomotive Traction Converters

研究了机车牵引变换器在两种调制方法下的应用,分析了两种调制方法下的各自实现过程,在各实现方法下进行了分别对比,说明了同步空间矢量脉宽调制(SVPWM)与特定谐波消除脉宽调制(SHEPWM)的不同点和相同点。最后用实验的方法对比分析了两种方法下开关频率、开关损耗及过渡过程中电流的变化情况。对比结果表明:两种方法均可以作为机车牵引变换器的调制策略,同步SVPWM过调制方法过渡过程平滑,但低次谐波含量较大;多模式SHEPWM的总谐波含量小,能够减小转矩脉动、降低电机损耗和开关损耗,优势明显。

The application of locomotive traction converter under two modulation methods is studied.The respective re- alization processes of the two modulation methods are analyzed.The comparison between the two methods is made.The differences and similarities between space vector pulse width modulation（SVPWM） and selective harmonic elimination pulse width modulation （SHEPWM） are illustrated.At last, the switching frequency, switching loss and the current change in the process of transition between the two methods are compared and analyzed experimentally.The comparison results show that both methods can be used as the modulation strategy of locomotive traction converter ,the transition process of synchronous SVPWM over-modulation method is smooth, but the content of low-order harmonic is large.The total harmonic content of multi-mode SHEPWM is small and can reduce torque ripple ,motor losses and switching losses, the advantages are obvious.