峰值电流控制DC/DC变换器的恒值限流方法

讨论了峰值电流控制DC/DC变换器中的稳定性问题,分析了解决稳定性问题的斜坡补偿原理及实现方法,研究了斜坡补偿对开关管电流峰值限流保护点的影响,揭示了过流保护值随占空比减小而增大,且有损开关管安全工作.提出了同步补偿实现开关管恒定峰值限流保护解决方案.并以UC3846控制的交错并联双管正激变换器为例进行了实验研究,给出了实现电路的设计原理和方法,验证了理论分析的正确性和可行性.

Over Current Protection for Peak Current Controlled DC-DC Converter

The stability of peak current controlled dc-dc converter is discussed in the paper. The principle of slope compensation for peak current control to ensure system stability is analyzed, and the effect on the over current protection point of the power switches caused by slope compensation is researched in detail. It is discovered that the peak current limitation increases along with the duty cycle decreases and the safety operation of the switches is damaged greatly. A novel solution to improve over current protection with constant peak current limitation is proposed by introducing synchronous slope compensation into the current limition function instead of constant voltage original. The design principle and method of the protection circuit based on UC3846 PWM controller for interleaved dual-forward converter are presented, and experimental results verify the analysis.