四开关Buck-Boost变换器的三模式控制方法研究

针对四开关Buck-Boost变换器在两模式运行时,其输入输出电压接近时模式切换频繁以及开关管难以运行在极限占空比下的问题,提出了一种基于平均电流控制的Buck、Buck-Boost、Boost三模式切换策略。该策略在原有Buck、Boost两模式的基础上,通过检测输入电压单元来控制调制信号偏置电压,实现四开关BuckBoost变换器在Buck、Buck-Boost、Boost三模式下平滑切换,使开关管在宽输入电压范围内工作在有效占空比区间。通过使用平均电流控制来限制电感电流变化,确保变换器的安全可靠运行。最后搭建saber仿真模型和硬件实验平台,验证了所提控制策略的可行性。

Study on Three-mode Control Method for Four-switch Buck-Boost Converter

When a four-switch Buck-Boost converter is under a dual-mode operation, the modes will switch over frequently and the switch tube is difficult to run under the limit duty cycle if the input and output voltages approach each other. To solve this problem, a three-mode switching strategy of Buck, Buck-Boost, and Boost is proposed based on average current control. On the basis of the original dual-mode of Buck and Boost, by adding an input voltage detecting unit to control the bias voltage of modulation signals, this strategy can make sure that the four-switch Buck-Boost converter can smoothly switch over Buck, Buck-Boost, and Boost, and make the switch tube operate in the effective duty cycle range in a wide input voltage range. Average current control is used to restrain the variation of induction current, thus ensuring the safe and reliable operation of the converter. Finally, a saber simulation model and hardware experimental platform was established to verify the validity of the proposed control strategy.