《48V25A直流高频开关电源设计》》-毕业论文.doc

摘 要 PAGE PAGE 34 摘 要 目前开关电源向着高频、高可靠性、低功耗、低噪声、抗干扰和模块化方向发展，本论文设计了一种通信系统常采用的48V/25A直流高频开关电源。 本论文首先对高频开关电源的主电路进行了设计，分析了零电压软开关技术在移相全桥电路中的应用，开关电源的软开关技术采用移相PWM控制，通过相移芯片UC3875产生具有一定相序的脉冲去触发MOSFET管。在主电路设计中，进行了高频变压器的设计，并对输出整流电路进行了分析、研究与设计。 其次，对开关通信电源的控制电路进行了设计。控制电路以UC3875芯片为控制核心，采用闭环控制模式，实现系统的稳压和限流。另外，对控制系统的过电流保护、过压保护、过热保护电路等保护电路进行了设计。 最后，用SABER仿真软件对电路进行了系统仿真与验证，仿真结果表明了设计的正确性。 关键词： 软开关， UC3875， 移相控制 Abstract Abstract At present, the switching power supply developed high frequency, high reliability, low energy consumption, low noise, interference and modular direction. That is to develop the inverter power source controlled by microcomputer which adopts soft-switches . This researching task is put forward on the base of discussing the characteristics and virtues of the welding inverter. The phase-shift chip UC3875 is adopted phase-shift pulse width modulate. The design about high frequency transformer is given .The amplified circuit and the commuted circuit are designed. The paper mostly researches and designs the soft-switch control system. Secondly, the control circuit, the protect circuit of the power supply are analyzed and designed. Its control circuit is centered on UC3875, uses a control that based regulation to realize the function is composed of analog of voltage-stabilization and current-limited. In addition, the safeguard circuit that mainly consists of over current, over heat, over voltage and circuit are studied and designed in the paper. And the circuit is simulated by the SABER, Simulation results show that the design is correct. Key words: soft-switch, UC3875, phase-shift 目 录 目 录 TOC \o 1-4 \h \z \u HYPERLINK \l _Toc169760371 摘 要 PAGEREF _Toc169760371 \h I HYPERLINK \l _Toc169760372 Abstract PAGEREF _Toc169760372 \h II HYPERLINK \l _Toc169760373 目 录 PAGEREF _Toc169760373 \h III HYPERLINK \l _Toc169760374 第一章 引 言 PAGEREF _Toc169760374 \h 1 HYPERLINK \l _Toc169760375 1.1开关通信电源系统的介绍 PAGEREF _Toc169760375 \h 1 HYPERLINK \l _Toc16976037