一种以降低逆变器开关损耗为目标并考虑中点电位平衡的适用于中点钳位式三电平逆变器的调制方法

A Modulation Method With Reduced Switching Losses and Considering the Neutral Point Voltage Balance Suitable for the Neutral Point Clamped Three-Level Inverter

介绍了中点钳位式(neutral point clamped,NPC)三电平逆变器载波脉冲宽度调制(carrier-based pulse width modulation,CBPWM)、空间矢量脉冲宽度调制(space vector PWM,SVPWM)、最小开关损耗脉冲宽度调制(switching loss minimize PWM,SLPWM)3种典型的调制策略。当中点电位偏移时,提出了一种非对称载波脉冲宽度调制(asymmetric carrier disposition PWM,ASPDPWM)策略,可以在中点电位偏移时输出正确的PWM序列,有效抑制逆变器输出的低频谐波含量。分析了基于载波移位脉冲宽度调制(carrier disposition PWM,PDPWM)策略的中点电位平衡方法。提出了一种SLMPWM和PDPWM混合调制策略,这两种调制策略的切换采用滞环控制方式。在实验室搭建了NPC三电平逆变器实验平台,通过阻感性负载和永磁同步电机负载验证了混合调制策略的有效性。实验结果验证了SLMPWM和PDPWM的混合调制策略能够有效降低开关损耗和控制中点电位。

Carrier-based pulse width modulation （CBPWM）, space vector PWM （SVPWIvl） and switching loss minimize PWM （SLMPWM） for the neutral point clamped （NPC） three-level were introduced firstly. In the case of the neutral point voltage offset, an asymmetric carder disposition PWM （ASPDPWM） strategy was proposed, which can output PWM sequence correctly and suppress low frequency harmonic content of the inverter output effectively. A neutral point voltage balance method based on carrier disposition PWM （PDPWM） strategy was analyzed. A hybrid modulation strategy containing SLMPWM and PDPWM was proposed, and hysteresis control was adopted to switch between the two modulation strategies. A NPC three-level converter experimental platform was built in the laboratory. The effectiveness of the hybrid modulation was verified with the resistive inductive load and permanent magnet synchronous motor load. The experimental results show that hybrid modulation strategy containing SLMPWM and PDPWM can reduce the switching losses and control the neutral point voltage effectively.