摘要

随着微处理器与数字处理器的发展，需要为它们提供更低的输出电压，更大的电流。因此，对低压大电流正激变换器及其相关技术的研究，在近几年得到广泛的关注。

本文首先介绍了传统正激变换器高频变压器磁复位技术，比较了各种磁复位拓扑的优缺点，最后选择了有源箝位正激变换器作为本次设计的主拓扑。其次，分析了有源箝位正激变换器的工作过程，并对其中的典型参数进行了计算推导。再次，在分析了三种驱动方式的基础上，对有源箝位正激变换器专用驱动芯片NCP1562进行管脚功能介绍，以及外围电路的搭建。主要包括辅助电源，过流、过欠压保护，振荡频率，误差反馈输入等相关电路的设计。最后，完成器件的参数计算，器件的最终选型，并采用MATLAB对系统进行仿真。得到电压、电流的输出波形，完成了对波形的简要分析，论证了理论分析的正确性和设计方案的可行性。

关键词　正激变换器有源箝位变压器磁复位

Abstract

With the development of microprocessor and digital processor, lower output voltage and higher current is needed to provide. Therefore, research on lower output voltage and higher current forward converter is widely focused on.

Firstly, the high frequency transformer magnetic reset technique of traditional forward converter is introduced in this paper. The advantage and disadvantage of various magnetic reset topologies is compared. An active clamp forward converter is chosen as the main topology of this design. The working process of active clamp forward converter and the typical parameters of the calculation and derivation are analyzed. Thirdly, based on analysis of the three driving modes, pin function of the active clamp forward converter drive chip NCP1562 is introduced and the peripheral circuit is constructed. Mainly includes the auxiliary power supply, over-current protection, over-voltage or under voltage protection, oscillation frequency, error feedback input and so on. Finally, the calculation of parameters of the device, the final selection device, and use MATLAB to simulate system is completed. The output waveform of voltage and current is briefly analyzed. The correctness and feasibility of the theoretical analysis of the design scheme is proved.

Keywords　Forward converter Active clamp Transformer magnetic reset