两级式逆变器中间母线电压低频纹波抑制

两级式单相逆变器输出电压和电流都是低频交流电,输出瞬时功率中除含有直流量外还含有2倍输出频率的脉动量,造成中间母线电压出现二次纹波分量。为解决逆变环节产生的谐波引起母线电容发热从而危及母线电容的运行寿命以及母线电压脉动可能导致逆变输出电压畸变的问题,提出了一种通过改变前级直流变换器外环电压控制器参数以实现母线电压低频纹波抑制的方法,并研究了两级式直交逆变器中间母线电容电压特性,通过分析逆变环节输入电流中直流分量、二次谐波分量等表达式,从而揭示两级式逆变器中间母线电容低频电压纹波的产生及其影响因素。方法中前级直流变换器、后级逆变器均采用电压电流双闭环控制。仿真和实验结果表明该控制方法是正确、可行的,且母线电压低频纹波抑制效果明显。

Low Frequency Ripple Rejection of Middle Bus Voltage of Two-stage Inverter

The output voltage and current of the two stage single-phase inverter are the low frequency AC signal. The output power has both DC component and the Secondary ripple component, which results that the middle bus voltage contains the secondary ripple component. In order to solve the heating problem that will reduce the operation life of the middle bus capacitor caused by the harmonic component of the inverter and the problem that the voltage ripple of the middle bus capacitor may cause the output voltage distortion, a new method is proposed to realize the low frequency ripple rejection by changing the external loop voltage controller parameters in the front stage DC converter. In order to study the voltage characteristics of the middle bus capacitor in the two stage DC-AC inverter, the paper analyzes the DC component and the two harmonic component of the input current of inverter, which reveals the generation and the influencing factors of the low frequency voltage ripple of the middle bus capacitor of the two stage inverter. Average current control method is used in both the first stage and the second stage. Simulation and experimental results show that the proposed control method is correct and feasible, and the low frequency ripple of bus voltage is significantly suppressed.