三电平逆变器电容电压柔性平衡控制策略

Flexible Capacitor Voltage Balance Control for Three-level Inverter

针对二极管箝位型三电平逆变器的电容电压平衡问题,分析了PWM载波通式中的若干自由度,提出了基于改变载波零偏的三电平逆变器电容电压控制策略,从矢量作用时间方面研究了该控制策略在典型区间内的作用原理,并将结论推广到全部区间。进一步从直流侧电容电压的波动特性和输出性能方面考虑,提出了改进的三电平柔性平衡控制策略,通过在电容电压反馈中引入低通滤波环节和在输出控制中引入电容电压前馈环节来实现。在二极管箝位型三电平逆变器实验平台上得到实验结果证明上述控制策略的有效性。

Aiming at the capacitor voltage balance problem of diode clamped three-level inverter,degrees of freedom of the PWM carrier general formula is analyzed,and a capacitor voltage balance control strategy for three-level in-verter is proposed based on shift of the carrier bias.Operation mechanism of this strategy is analyzed from the point of vector dwell time,first within some typical ranges and final in entire range.Furthermore,considering the wave char-vacteristics of DC side capacitors＇ voltage and the high priority of output performance,an improved three-level flexi-ble capacitor voltage balance control strategy is proposed.It employs a low pass filter module on the capacitor voltage feedback and a feed forward module on output voltage control.The experimental results on a diode clamped three lev-el inverter platform prove the effectiveness of the above control strategies.