Research on common-mode voltage reduction in multi-level inverter

PWM technology for common-mode voltage reduction in three-level inverter is investigated whereas common-mode voltage generated by two-level inverter can only be reduced by an additional filter. With effective on-off states in three level inverter, common-mode voltage generated by three-level inverter is analyzed, then a conclusion is gained that common-mode voltage can be reduced by using software in odd-level inverter. Reducing and canceling common-mode voltage methods are presented using SPWM (Sinusoidal Pulse Width Modulation). Simulation results validate their correctness. A comparison is also made among their effects on motor performance, and then usability of the proposed methods is analyzed.