大容量PWM电压源逆变器的LC滤波器设计

LC filter design for high-power PWM voltage source inverter

针对大容量变频调速装置中LC滤波器设计困难的问题,提出了特定消谐脉冲宽度调制(SHE-PWM)的逆变器优化控制方案。以三电平中点箝位(NPC)逆变器为研究对象,采用分段同步SHE-PWM保证整个调速范围内LC滤波器的谐振抑制问题,并给出了LC谐振频率的设计方法。采用此方法可以使大容量开关器件工作在较低的开关频率下。分析了LC滤波器对逆变器输出电流和机端电压的影响及滤波电容与电机之间的自激等问题,并据此提出了电抗参数和电容参数的具体设计原则和方法。在一台基于三电平NPC逆变器的6kV变频调速装置上的试验结果验证了所提方法的有效性。

For medium voltage drives based on pulse width modulation (PWM) voltage source inverters, the LC filter design is difficult due to the LC resonance. A new optimal LC filter design method was developed based on a threelevel neutral point clamped (NPC) inverter and selected harmonic eliminated PWM. The excitation of the resonance is actively damped throughout the whole operating frequency range for low switching frequencies. The effects of the LC filter on the motor voltage and inverter output current were analyzed. A parameter design method was developed for the inductor and capacitor designs. The proposed method was confirmed by experimental results on a 6 kV NPCVSI based medium voltage drive.