基于开关电感结构的混合升压变换器非线性现象研究

Nonlinear phenomena in the hybrid step-up converter with switched-inductor structure

将开关电感结构嵌入到传统Boost变换器中可以显著提高Boost变换器的电压传输比,同时减少开关器件的电流应力,降低损耗,提高效率,具有广阔的应用前景.本文首次研究了基于开关电感结构的混合升压变换器的分岔和混沌现象,导出了连续电流模式下的离散迭代映射模型,采用分岔图分析了电路参数对系统性能的影响,发现此变换器不仅发生了倍周期分岔、边界碰撞分岔、切分岔和阵发混沌,还存在一种特殊的现象:随着电容C和电感L2的减小,电路的运行状态并非严格经历1倍周期、2倍周期和4倍周期,而是在4倍周期期间发生了分岔轨迹相交的情况,在相交的一点,变换器工作于周期3.最后通过典型的时域波形和相轨图验证了这种特殊现象的存在.研究结果表明,当电路参数变化时,基于开关电感结构的混合升压变换器比传统低维Boost变换器具有更加复杂、多样化的非线性现象.

Inserting the switched-inductor structure into a traditional Boost converter can increase its line-to-output voltage ratio significantly, decrease the current stresses in the switching elements, reduce losses, and improve efficiency at the same time, which makes it find wide applications in prospect. The bifurcation and chaos phenomenon occurring in the hybrid step-up converter with switched-inductor structure is studied for the first time so far as we know. The discrete iterated mapping model under continuous current mode is established, while the effects of circuit parameters on system performance are analyzed by using bifurcation diagrams. Not only period-doubling bifurcation, border collision bifurcation, tangent bifurcation and intermittent chaos are found in this converter, but a special phenomenon can also be observed according to the simulation result. With the decrease of the capacitance C and inductance L2, the circuit experiences roughly a period, double-period and quadruple-period, and during the quadruple period, two of the bifurcation lines will cross, which leads to the system exhibiting a period-3 behavior at that point. Finally, the existence of this special phenomenon is confirmed by the typical time-domain waveforms and phase portraits of the converter. Results obtained indicate that there can be more complicated and diversiform phenomena in the hybrid step-up converter with switched-inductor structure than in the traditional low-dimensional Boost converter as the circuit parameters vary.