SPWM静态调制误差分析

Analysis of steady-state modulation error of SPWM

脉宽调制(PWM)技术是电力电子领域的核心技术,为了分析各种相关因素对PWM输出结果的影响,文中提出了PWM的静态调制误差(PWMSME)的概念。以SPWM为例,在Fourier变换的基础上推导出了其PWMSME随频率变化的精确数学表达式,分析了载波频率、死区及采样方式对PWMSME的影响,并给出了其量化的表达式。指出了在载波频率较低的情况下,由“冲量等面积原理”计算的输出结果会产生一定的误差。最后,通过对PSCAD建立的H桥逆变器模型的仿真结果、实验数据及相应公式的数值计算结果对比分析,验证了文中结论的正确性。

PWM technology is one of the key technologies in the area of power electronics. The concept of PWM Steadystate Modulation Error （PWMSME） is proposed to analyze the affections of all kinds of factors. Taking SPWM for example, the authors produce an accurate mathematic representation of PWMSME based on Fourier transform, analyze the affections of carrier frequency, deadband and sample methods to PWMSME. And the expression of quantification is obtained. It is pointed out that, according to the theory of homalographic of impulse, there＇s some calculation error in the case of low carrier frequency. At last, the simulation model of a H-bridge inverter based on unipolar SPWM is set up in EMTDC/PSCAD. By analyzing the difference between simulation and experiment results and calculation results, the conclusions are verified.