H桥级联型逆变器的迭代谐波消除方法

Iterative Harmonic Elimination Method for Cascaded H-bridge Inverters

多电平逆变器在中高压变频器中有着广泛的运用,其中尤以H桥级联型逆变器运用最广。人们对阶梯电压波形中谐波的消除方法大多是在经过傅里叶变换后需要求解高次多变量多项式方程。为此,提出了一种不同的方法,它以等面积法和谐波注入为基础,利用该方法,不论有多少阶梯电压波形,都仅需解几个简单的方程和进行数次迭代就可以有效消除谐波。并以最多5个开关角阶梯电压波形为例,利用所提出的方法,对逆变器调制系数范围在0.1~0.99的变化可以取得很好的谐波消除效果。最后在H桥级联型逆变器上进行实验研究,实验结果验证了所提方法的可行性。

We put forward a new method for eliminating iterative harmonics of cascaded H-bridge inverters,which is based on equal area criteria and harmonic injection.With the proposed method,regardless of how many voltage levels are involved,only several simple equations and several iterations are needed.The results of a case study with maximum of five switching angles for step voltage waveform show that the proposed method can be used to achieve excellent harmonic elimination performance for the modulation index range at least from 0.1 to 0.99.Finally,experimental results verify the feasibility of the proposed method in cascaded H bridge inverter.