中文摘要：

为减小逆变器负载端共模电压幅值，保证电机负载和敏感设备的安全运行，提出一种改进的变延时随机脉宽调制（VD．RPWM）策略。该方法通过加入随机延时时间调整开关周期实现了开关频率的随机变化，基于对采样周期选择所存在问题的分析，通过引入随机系数解除采样周期对逆变器输出性能和谐波频谱分散能力的同时约束。达到了合理选择开关周期变化范围的目的。仿真和实验验证了开关频率变化范围约束后的改进VD-RPWM策略在实现有效调制的同时。能抑制共模电压，分散共模电压频谱。

英文摘要：

In order to reduce the amplitude of common-mode voltage in the load end of inverters and guarantee thesafe operation of motors and sensitive equipment, an improved variable-delay random pulse width modulation （VD-RP-WM） strategy is proposed.The random variation of switching frequency is realized in this method by adding randomdelay time to adjust switching period.Based on analyzing the problem existing in choosing sampling period,a randomcoefficient is introduced to remove constraints to the inverter output performance and harmonic spectrum dispersing abil-ity from the sampling period.Then the variation range of switching frequency is chosen properly.The simulation andexperiment verify that common-mode voltage is reduced and frequency spectrum is dispersed with VD-RPWM after con-straining the variation range of switching frequency.