Performance characteristics of the reduced common mode voltage near state PWM method

The Near State PWM (NSPWM) method, which has low common mode voltage/current is proposed for three-phase voltage source inverter drives. The method is described and its voltage linearity, output current ripple, DC bus current ripple, common mode voltage and output line-to-line pulse patterns are thoroughly studied and compared with classical PWM methods. The theory, simulation, and laboratory experiments illustrate that NSPWM has low common mode voltage, results in less common mode current, has low switching losses comparable to those of DPWM methods, has low current ripple compared to the classical methods, and exhibits no significant overvoltage problems in long cable applications as its pulse pattern involves a sufficient distance between the polarity reversing voltage pulses.