该变频器采用单元串联多电平技术，可以得到阶梯SPWM波形，无需输出滤波器，可直接驱动普通电动机。
The (frequency) converter (adopted) multilevel technology with cells series, which could obtain stepped SPWM waveforms, and could drive ordinary motor directly with no output filter.
文中以15 个功率单元串联式结构为例， 分析中性点漂移技术，研究功率单元故障时的处理方法。
The article takes 15-power modules in series as an example, to analyze the neutral point drifting technology and research the treatment of module failure.
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