【摘要】 提出了一种二极管箝位型(NPC)三电平逆变器载波调制方法,该方法能消除三电平逆变器直流侧中点电位低频振荡,适用于任意非线性负载情况。该方法从空间矢量脉宽调制方法和载波调制方法本质联系出发,通过向调制波中注入一定的零序电压分量,达到了与空间矢量脉宽调制同样的电压利用率。该方法将调制波分成2部分,分别与载波进行比较,来决定开关管的工作状态。对直流侧中点电位采用了闭环控制,通过检测直流侧电容电压的大小和三相负载电流的方向,对每相的2部分调制波进行适当的调节,从而调整流入或流出中点的电流的作用时间,有效地保证了系统运行过程中直流侧电容电压平衡。该方法简单易行,易于数字化实现。仿真结果验证了该方法的正确性和可行性。更多还原

【Abstract】 A carrier-based PWM is proposed for three-level neutral-point-clamped inverter,which avoids the low-frequency oscillation of its neutral-point voltage,suitable for any nonlinear load conditions.Based on the relationship between the space vector PWM and the carrier-based PWM,a proper zero-sequence voltage component is injected into the modulation signal to achieve the same maximum voltage utilization as that of SVPWM.Two modulation signals are compared respectively with the carrier to decide the state of output switch at each phase of the inverter.Close-loop control is designed for the neutral point voltage at DC-side.The DC-side capacitor voltage and three-phase load current are monitored and the modulation signals are accordingly modified to adjust the effective time of neutral point current to guarantee the capacitor voltage balance at DC-side.This method is simple and easy for digital implementation and its correctness and practicability are verified by simulations.更多还原