Abstract: After the addition of dead zone, the carrier disposition PWM modulation method could have some problems, such as distortion of current waveform and decreasing of voltage utilization ratio. Taking the TNPC type three-level inverter as a researching object, a novel method of the carrier disposition PWM modulation with no dead zone for three-level inverter was proposed, in which three PWM modulation signals were generated by using triple carrier wave. By analyzing the effect caused by the dead zone in different operating states, on and off rules of power switches were derived. Simulation results in MATLAB/Simulink environment show that the proposed method can reduce harmonic content of the current, and increase the amplitude of the fundamental current and the voltage utilization ratio, which realizes no-dead-zone control of the TNPC type three-level inverter.

Key words: TNPC inverter, three-level, carrier disposition PWM, no dead zone