电流谐波最优PWM开关角计算及数字实现

摘要

介绍了三电平变频器在低开关频率运行下的电流谐波最优PWM(CHOPWM)方法,对其基本原理及开关角的求解进行了深入分析和研究.对三电平变频器输出电压、电流进行傅里叶级数分析,求出电流畸变率的表达式；令电流总畸变率作为目标函数,令电压基波幅值等于参考电压幅值作为非线性约束条件,进而利用MATLAB优化工具箱中的ga函数和fmincon函数求解出CHOPWM开关角.用MATLAB软件搭建了仿真模型,对开关频率为250Hz时的开关角求解结果进行仿真验证.对基于TMS320F2812的CHOPWM数字实现进行分析.最后,通过实验验证了开关角求解方法的有效性.%The current harmonic Optimal PWM (CHOPWM) method for three level converters operating at low switching frequency is introduced. Its basic principle and the solution of the switching angle is researched. The three -level inverter output voltage and current is analyzed using fourier series and the expression of current distortion rate is calculated. The expression of current distortion rate is regarded as a nonlinear transcendental equation and the voltage fundamental amplitude is equal to the reference voltage amplitude seen as nonlinear constraints. Then the switching angle of CHOPWM is solved by using the function of ga and fmincon function in MATLAB optimization toolbox. A simulation model was built using MATLAB software. Results of the switching angle at 250Hz switching frequency are verified. CHOPWM digital implementation is analyzed based on the TMS320F2812. The experimental results verify the availability of the scheme.