一种新型大功率升降压变换器及控制方法

摘要

现有的升降压拓扑中双管级联变换器最符合高效大功率场合的使用要求,但如果工作模式标准选择不当,串联结构和Boost电路的非线性直流增益很容易在升降压转换过程中产生严重的振荡.本文提出了一种新颖的大功率IPOSBHB变换器,阐述了其电路结构及基本关系,建立了降压模式和升压模式下的开环小信号模型,设计了载波平移的组合控制方法,分析了升降压模式切换时传递函数的不一致性、占空比的不连续性和输入电压的扰动对变换器输出特性的影响,并给出了补偿措施.本文提出的载波平移组合控制策略和补偿方法很容易实现稳态时的高效控制和升降压模式切换时的平滑过渡,同时降低了输入电压扰动的不利影响.通过一台15 kW样机对本文提出的理论加以验证.%Two-switch cascade converter is the most appropriate solution for efficient high-power applications among the existing converter topologies.However,the cascade structure and the nonlinear dc gain of Boost circuit are more likely to cause severe oscillations if the criterion for the selection of the operation mode is chosen improperly during step-up/step-down transition.A novel high-power IPOSBHB converter was proposed.The circuit structure and basic relations were analyzed.And the open-loop small-signal model of Buck mode and Boost mode was established.The carrier wave parallel-shifting combinational control method was designed.The inconformity of the transfer functions,the discontinuity caused by duty cycle and the disturbance of input voltage were analyzed and the methods for compensation were also proposed.The carrier wave parallel-shifting combinational control strategy and the compensation methods proposed were easy to be carried out to achieve effective control at steady state and achieve smooth transition at step-up/step-down mode change,and also reduce the adverse effect caused by the disturbance of input voltage.A 15 kW prototype is used to validate the proposed theory.