大容量400Hz逆变器输出LC滤波器设计和低次谐波抑制

Design of Output LC Filter and Low Order Harmonics Suppression in High Power 400Hz Inverter

为了有效抑制大容量中频400Hz/115V逆变器输出电压中的谐波,推导了两级级联H桥载波移相正弦脉宽调制(SPWM)时输出电压波形的数学表达式,可准确得到逆变桥开环状态下输出电压的基波和各次谐波含量,为输出滤波器的设计提供了理论依据。同时考虑滤波电感上的基波压降、电感电流纹波以及无功容量等因素,提出了LC滤波器的设计方法。另外,通过在逆变器外环和内环分别采用基波谐振控制和3、5、7次谐振控制,不仅可以消除稳态误差,还可以补偿3、5、7次谐波。通过仿真和实验证明了理论分析的正确性。

In order to suppress harmonics content in high power medium frequency 400Hz/115V inverters,the mathematical expression for carrier phase-shifted sinusoidal pulse width modulation（SPWM） waveform based on the cascaded topology with two H-Bridge units is derived.Then fundamental and each order harmonic＇s content can be obtained accurately,so the LC filter design has a theoretical base.The output LC filter is designed to eliminate high-order modulation harmonics simultaneously considering the fundamental voltage drop across the filter inductor,the inductor current ripple and reactive capacity.Fundamental resonant control and the 3rd,5th and 7th resonant control is adopted in inner loop and outer loop,respectively,which can eliminate steady-state error and compensate the 3rd,5th and 7th harmonics.The simulations and experiments verify the effectiveness of the proposed scheme.