PWM control method to eliminate Common Mode Voltage in three level T-Type inverters

In this paper, Common-mode voltage (CMV) is responsible for overvoltage stress to the winding insulation and bearing damage of an AC motor. High dv/dt of CMV causes leakage currents, which create noise problems to the equipment installed near the converter. This paper presented modulation strategy to eliminate CMV three level T-Type inverter (Zero CMV 3L (TI)-I-2) that substantially eliminates CMV. The principles of selecting suitable triangle carrier signals for the T-Type is described. This PWM control method can mitigate the peak value to 95% as compared to the conventional sinusoidal pulse width modulation method. A prototype is constructed to verify the operating principle of the three-level T-Type inverter. Simulation and experimental results are presented.