一种两级式逆变器在线效率优化方法

An On-line Efficiency Optimization Method of Two-stage Inverters

归纳了影响两级式逆变器效率的因素。对前级为升压电路、后级为全桥逆变电路的典型逆变器,推导了中间母线电压U_b与各开关管、二极管和电感之间的损耗公式,指出其影响的复杂性。在此基础上,提出了在线调整U_b优化系统运行效率的方法。在U_b允许波动的范围内,通过检测输入电压U_(in)和电流I_(in)、输出电压u_o和电流i_o来计算效率η,采用变步长法调整U_b以获得效率η在线提升。分析了调整U_b的幅值△U_b和时间步长△t的考量条件。最后在一台负载为400W的样机上试验,采用了该方法后效率提升了1.16%,实验波形也证明了方法的有效性。

The influencing factors of efficiency of two-stage inverters are summarized.In a typical inverter consists of a front-end Boost converter and a back-end full-bridge inverter, the power-loss equations involving the middle bus voltage Ub of the power switches,power diodes and inductances,are induced.And the complexity of the influence is pointed out.And on this basis an on-line efficiency-optimizing method by adjusting Ub is presented.By calculating the efficiency η after measuring the input voltage Um and input current Im, output voltage Uo and output current io, an Ub- adjusting method adopting step-altering strategy in the range of permitting fluctuation of Ub can improve the system efficiency.The key design of the voltage-interval AUb and time-interval At is described.Finally,a prototype with 400 W rated load is built.Its efficiency is increased 1.16%, and the test waveforms also verify the proposed method available.