二极管箝位型多电平逆变器全范围电容电压平衡的PWM调制方法

电容电压偏移是二极管箝位型多电平逆变器的主要缺点。空间矢量调制和正弦载波调制方法，在调制度较高且功率因数较低时，电容电压出现低频波动。该文首先建立含电容电压的二极管箝位型三电平逆变器的脉冲宽度调制(pulse-width modulation，PWM)模型，提出一种新的调制方法，只需满足三相电流之和为零，该方法在任意调制度和功率因数下都能确保电容电位的平衡。并对算法累积误差进行修正。实验结果表明，这种方法较以前的解决方案能更好地平衡电容电压。最后将算法拓展到二极管箝位型任意电平数逆变器的调制中。

PWM Algorithm for Diode Clamped Multi-level Voltage Source Inverter With Capacitor Voltage Balance Under Full Condition

The DC-capacitor-voltage drift is the main technical drawback of diode clamped multi-level inverter (DCMLI). The modulation approaches based on the space vector pulse width modulation (SVPWM) and the sinusoidal carrier-based modulation (SPWM) are incapable of controlling the capacitor voltage for high modulation indexes and low power factors in diode clamped three-level inverter. A novel PWM theory including capacitor voltage is modeled. This paper presents a new modulation scheme for the complete control of the capacitor voltage in diode clamped three-level inverter, the only requirement for this scheme is that the summation of the output three-phase currents equals zero. The method to eliminate accumulation error of algorithm is presented. The performance of this modulation approach and its benefits over other previously proposed solutions are verified experimentally. This approach is extended to modulation of number-level DCMLI.