双管Buck-Boost变换器的输入电压前馈控制策略

An Input Voltage Feedforward Control Strategy for Two-switch Buck-Boost DC-DC Converters

双管Buck-Boost变换器适用于宽输入电压范围场合。采用双调制–单载波的两模式控制策略可实现其整个输入电压范围内的高效率和工作模式的自动平滑切换,其工作模式即为高输入电压区间的Buck模式和低输入电压区间的Boost模式。为抑制输入电压扰动对输出电压的影响,通过建立双管Buck-Boost变换器不同工作模式下的小信号模型,推导相应的输入电压前馈函数,并分析电路参数变化对前馈函数的影响,进而提出一种带输入电压前馈的两模式控制策略。采用所提出控制策略的双管Buck-Boost变换器,可实现工作模式和相应输入电压前馈函数的同时自动选择,及工作模式的近似平滑切换,从而保证变换器整个输入电压范围内的高效率和良好的输入暂态响应。为更好地展现所提出控制策略的优点,对带输入电压前馈和不带输入电压前馈的两模式控制策略进行比较。最后,实验室搭建一台原理样机,并对所提出的控制策略进行实验验证。

The two-switch Buck-Boost（TSBB） converter is suitable for wide input voltage applications,and a two-mode control scheme with two modulation signals and one carrier can be adopted to achieve high efficiency and automatic modes-switching over the entire input voltage range.The corresponding operating modes are the Buck mode with high input voltages and the Boost mode with low input voltage.In order to reduce the influence of the input voltage disturbance on the output voltage,input voltage feed-forward（IVFF） functions based on the small-signal models of different operating modes were derived,and the effect of the variable circuit parameters on the IVFF functions was analyzed,then a two-mode control scheme with IVFF compensation was proposed.With this proposed control scheme for the TSBB converter,automatic selections of operating modes and the corresponding IVFF functions can be achieved simultaneously.Besides,nearly smooth switching between Buck and Boost modes is guaranteed.Then,high efficiency and improved input transient response over the entire input voltage range are both achieved.For exhibiting the advantages of the proposed control scheme clearly,comparisons between the two-mode control with and without IVFF compensation had been presented in this paper.Finally,a suitable power prototype was fabricated to validate the effectiveness of the control scheme.