Study of compensating technique in PWM control for three-level inverters

As to the Narrow Pulse Width (NPW) Problem of high-voltage high-power semiconductors, a novel compensating NPW technique of named Zero-Sequence Voltage Injection (ZSVI) technique is first proposed to eliminate the influence of the NPW on the inverter. Injection of zero-sequence voltage to three-phase reference voltages can remove harmonic components and negative-sequence voltage components of the output voltage induced by narrow pulses. Simulation and experimental results show that the effect of narrow pulses can be compensated by using the technique, at the meantime neutral-point potential fluctuations can be controlled. Due to the ZSVI technique output voltages can be increased, the THD of output voltage can also be greatly reduced, and the THD of output voltage is no longer affected by increasing minimum turn-on pulse width and turn-off pulse width, therefore system reliability will be improved.