三电平逆变器PWM控制窄脉冲补偿技术的研究

STUDY OF COMPENSATING TECHNIQUE IN PWM CONTROL FOR THREE-LEVEL INVERTERS

针对高压大功率器件存在的窄脉冲问题,提出了新型的采用零序电压注入(Zero-SequenceVoltageInjection即ZSVI)补偿方法来消除窄脉冲的影响。在三相参考电压中注入零序电压,消除了输出线电压中窄脉冲带来的谐波分量和负序分量。仿真与试验结果表明,这种PWM方法在控制中点电位波动的同时,补偿了窄脉冲的影响。采用ZSVI方法后增加了输出电压,输出电压THD大大减小,输出电压THD不再受增加最大最小窄脉冲宽度影响,从而可以提高系统的可靠性。

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 referece 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.