基于三电平拓扑电路的五电平逆变器电流谐波最小PWM方法研究

Study on Current Harmonic Minimum Pulse Width Modulation for Five-Level Inverter with Three-Level Topology Circuit

降低功率开关器件的开关频率,可以减少逆变器的开关损耗,并提高输出能力,但随之会带来负载输出谐波增加、控制性能下降等问题。研究了一种基于三电平拓扑电路的五电平逆变器在低开关频率运行下的电流谐波最小PWM(CHMPWM)方法,采用遗传算法解决了CHMPWM求解的高精度初值问题,通过对低次谐波幅值的限制使负载输出电流具有良好的抑制谐波性能。基于MATLAB/Simulink系统仿真结果表明了该方法的有效性。

It is necessary to reduce the switching frequency of the power devices to boost the inverter＇s output power and reduce the switching loss in high power motor. However,larger current harmonic distortion and reduction of dynamic performance will be severe tests while using traditional pulse width modulation. To tackle this problem,the optimized PWM strategy was proposed. Current harmonic minimum PWM（ CHMPWM） for five-level inverter based on dual three-level inverter operating at low switching frequency was introduced. The constraint of the amplitudes of loworder harmonics was strengthened so that the output current would have a good harmonic performance. Nevertheless,it was difficult to obtain the high precision initial values for CHMPWM. So,genetic algorithm was used to deal with that problem. Finally,the validity of the control strategy proposed was verified through the MATLAB.