The increased phase number of multiphase systems enables us to exploit more degrees of freedom, such as the shape of phase carriers in pulsewidth modulation (PWM). The sawtooth carrier-based PWM (SCPWM) techniques are proposed in this article to reduce common-mode voltage (CMV) in both the peak-to-peak amplitude and the changing frequency, and it can be easily extended to symmetrical multiphase two-level inverters with any odd phase number. Theoretical analysis reveals that the switching between mirror-symmetrical carriers within one phase narrows the range of the sum of switching states in all phases, which leads to the reduction of CMV amplitude. Meanwhile, the overlapping of sawtooth carriers’ straight edges among different phases slows down the change of the sum of switching states, which results in the decrease of CMV changing frequency. Moreover, the effects of voltage harmonics injection and switches’ dead-time settings on the CMV reduction performance under the proposed SCPWM techniques are investigated. Finally, the experiment results in a five-phase induction machine and multiphase RL loads verify the improved CMV performance and the extensibility of the proposed SCPWM methods.

中文翻译：

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奇数相对称多相两电平逆变器共模降压的基于锯齿载波的PWM方法

多相系统增加的相数使我们能够利用更多的自由度，例如脉宽调制 (PWM) 中相位载波的形状。本文提出了基于锯齿波的 PWM (SCPWM) 技术来降低峰峰值幅度和变化频率的共模电压 (CMV)，并且可以很容易地将其扩展到对称多相两电平具有任何奇数相数的逆变器。理论分析表明，一相内镜像对称载流子之间的切换缩小了各相切换状态总和的范围，从而导致CMV幅度减小。同时，不同相位之间锯齿载波直边的重叠减慢了开关状态总和的变化，导致CMV变化频率降低。此外，还研究了电压谐波注入和开关死区时间设置对所提出的 SCPWM 技术下 CMV 降低性能的影响。最后，五相感应电机和多相 RL 负载的实验结果验证了改进的 CMV 性能和所提出的 SCPWM 方法的可扩展性。