双降压式全桥逆变器非线性现象的研究

双降压式全桥逆变器具有无桥臂直通、输入直流电压利用率高、效率高、续流二极管可优化选取等优点,因而在高压输出场合得到广泛的应用.本文研究了双降压式全桥逆变器的分岔和混沌现象,建立了电流闭环比例控制下的二阶离散模型,得到了不同时间段内的频闪映射模型;通过折叠图和分岔图分析了不同比例系数k对于系统稳定性的影响,并搭建了Matlab/Simulink仿真模型,得到了电流闭环比例控制时电流iL的时域波形和相图轨迹,并在频域下分析了分岔和混沌对系统频谱的影响.同时,利用分岔图的方法分析了输入电压E、滤波电感L和开关周期T等外部参数变化时系统的非线性行为.研究结果表明,正确选择双降压式全桥逆变器的电路参数对于其稳定运行具有重要意义.

Study on nonlinear phenomena in dual buck full-bridge inverter

Dual buck full-bridge inverter has the following advantages: it has no shoot-through problem, but receives high-utilization of DC input voltage, high efficiency and optimum selection of the freewheeling diodes, hence it attracts more and more attention in high power applications. In this paper, the bifurcation and chaos in the dual buck full-bridge inverter is studied. The two-dimensional discrete iterated mapping model under proportional control is established and stroboscopic maps in different periods of time are obtained. Effects of the proportional coefficient k on system performance are analyzed by using bifurcation diagram and folded diagram. A simulation model of dual buck full-bridge inverter is established based on Matlab/Simulink and the time domain waveforms and phase-space portraits for different proportional coefficient k are obtained. Besides, the effects of the bifurcation and chaos on the spectrum of the system are analyzed. Finally, the nonlinear behavior in the inverter caused by the variation of other circuit parameters such as input voltage E, inductance L, and the switching period of carrier wave T is discussed through bifurcation diagrams. Results show that the correct choice of circuit parameters of dual buck full-bridge inverter is very important for its stable operation.