不平衡中点电压下的三电平逆变器调制策略

A Three-Level Inverter Modulation Strategy under Unbalanced Neutral Point Voltage

提出了一种在不平衡中点电压下,基于通用调制模型(GMMPWM)的三电平逆变器的脉宽调制策略。GMMPWM由线电压与各电平之间存在的内在联系获得,并采用线电压和上下电容电压计算三相各个电平的持续时间,实现线性调制范围的扩展。避免了基于空间矢量脉宽调制策略的几何计算和基于载波脉宽调制策略的零序电压计算,可以实现高质量的输出线电压、最大化的线性调制范围和不平衡中点电压的控制。最后,通过仿真和试验结果验证了所提出方法的有效性。

A pulse width modulation(PWM) strategy based on general modulation model PWM(GMMPWM) for a three-level inverter with unbalanced neutral-point voltage was proposed.The GMMPWM is obtained by the intrinsic relationship between the line-to-line voltage and each level,the line voltage and the upper and lower capacitor voltages are used to calculate the duration of each level of the three phases,thereby an extension of the linear modulation range is achieved.The method avoids geometric calculation based on space vector pulse width modulation strategy and zero sequence voltage calculation based on carrier pulse width modulation strategy,which can achieve high quality output line voltage,maximum linear modulation range and unbalanced midpoint voltage control.The effectiveness of proposed PWM was verified by the simulation and experimental results.