I 准谐振式开关电源的设计 摘要 随着电力电子技术的发展，电力电子设备与人们的工作、生活的关系日益密切，而电子设备都离不开可靠的电源。开关电源产品广泛应用于工业自动化控制、特殊用途设备、仪器仪表、半导体制冷制热等领域。 目前，开关电源以小型、轻量和高效率的特点被广泛应用于电子设备，是当今电子信息产业不可缺少的一种电源方式。目前由于开关电源频率的提高，需要减少开关损耗。谐振电路，以使开关上的电压或通过开关的电流呈正弦波，在减少开关损耗的同时也可控制浪涌的发生，这种方式的开关电源称为谐振式开关电源。 准谐振开关电源使开关电源的可靠性、纹波干扰等问题得到很大改善，材料成本不增加而体积、重量却可以大大减少。除此之外，谐振式开关电源电路还可以克服PWM 方式对负载的瞬态响应较差和易辐射等缺点，利用高频驱动的作用，降低损耗，提高效率，减少噪声。其中，部分谐振方式，将会成为主流技术。部分谐振转换电路技术，在理论上即可实现高频化又可降低噪声，但部分谐振转换技术的实际应用仍存在着技术问题，故仍需在这一领域开展大量的工作，以使得该项技术得以实用化。 本文叙述了准谐振式开关电源的设计过程，描述了主电路的参数计算、器件的选择，介绍了 NCP1207 芯片实现准谐振控制的电路完整形式，实现了退磁检测、过流保护、过压保护、电压反馈。 关键字：准谐振，开关电源，反激式，NCP1207II Quasi-resonant switching power supply design Abstract With the development of power electronics, power electronics equipment becongme more and more Important for us, electronic devices can not do without reliable power. Switching power supply products are widely used in industrial automation and control, special purpose equipment, instrumentation, semiconductor refrigeration and heat and so on. At present, switching power supply to small, light weight and high efficiency characteristics are widely used in electronic equipment, and it is not a lack of power means. At present, because of the increased frequency ,switching power supply needs to reduce switching losses. Resonant circuit, in order to switch the voltage or current through the switch was a sine wave, reduces the switching losses and also control the surge in place.This approach is called resonant switching power supply. Quasi-resonant switching power supply make problem such as switch power source reliability , lines wave interference got very big improvement,and does not increase cost and reduce the volume and weight. In addition, the resonant switching power supply can overcome the poor transient response and easy radiation defects of PWM mode to load,and use of high-frequency drivers, reducing losses, improve efficiency, reduce noise. Part of the resonant will become mainstream technology. Part of the resonant converter circuit technology, in theory, but also can reduce the noise of the high frequency, but some of the practical application of resonant conversion technology, there are still technical problems, it still required much work in this area in order to make the technology to practical use. This paper describes the quasi-resonant switching power supply design process, describe the main circuit parameter calculation, the device of choice, introduced the NCP1207 chip quasi-resonant control circuit complete the form and realized the demagnetization detection, over-current protection, over-voltage protection, voltage feedback. Keywords: quasi-resonant,switching power supply, flyback, NCP1207III 目 录 摘要.I Abstract . II 第 1 章 绪论.1 1.1 准谐振开关电源的概述.1 1.1.1 开关电源的发展.1 1.1.2 准谐振开关电源的优点3.2 1.1.3 准谐振开关电源的缺点3.3 1.2 设计要求.3 1.3 完成设计方案.4 1.3.1 DC-DC 主回路拓扑.4 1.3.2 控制方法及实现方案.4 1.3.3 提高效率的方法及实现方案.4 第 2 章主电路设计.5 2.1 准谐振开关电源的基本原理4.5 2.2 输入电路.7 2.2.1 输入电路的选择.7 2.2.2 主要参数计算.7 2.3 变换电路.9 2.3.1 变压器设计.9 2.2.2 开关管选用.