基于SiC功率器件的反激式开关变换器设计

论文总字数：21858字

摘 要

现代电子技术飞速发展，各类家用用电器种类繁多并飞速发展，使得各类开关变换器广泛的被用于电子设备的电源及充电器当中。开关变换器是将高压交流电转换为低压直流电的装置，而其中，反激式开关变换器具有电路简单，设计简单、体积小巧、效率高、能够提供多路输出等优点，广泛适用于手机充电器等小功率设备。其性能的优劣将直接影响整体系统功能的效果。SiC MOSFET是一种禁带宽度宽的半导体器件，饱和电子漂移速度高，介电常数低，热导率高等特性。且其具有阻断电压高，工作频率高的特点尤其适应于高频驱动的开关电路。

本文介绍了一种使基于SiC MOSFET反激式开关器设计。为了达到电压的稳定输出，并消除输入电压和频率的不稳定干扰，电路中采用了多种模块，如EMI滤波、整流滤波电路、光电耦合反馈、尖峰电压吸收回路等。这样既提高了电路的效率和准确度，也提高了电路的稳定性和安全性。

Abstract

With the rapid development of modern electronic technology, all kinds of household appliances and the rapid development of a wide range, making all kinds of switching converters are widely used in power electronics and chargers among. Switching converter is a high voltage alternating current is converted to low-voltage DC device, and wherein the flyback switching converter has a simple circuit, simple design, small size, high efficiency, can provide multiple outputs, etc., widely used in mobile phone charger and other low-power devices. Its performance will directly affect the effectiveness of the overall system functionality. SiC MOSFET is a wide bandgap semiconductor devices, high saturated electron drift velocity, low dielectric constant, high thermal conductivity and other properties. And it has a high blocking voltage and high frequency characteristics, especially suitable for high-frequency switching circuit driving.

This article describes a way to make based on SiC MOSFET switch flyback designs. In order to achieve a stable output voltage and eliminates interference unstable input voltage and frequency, the circuit uses a variety of modules, such as EMI filter, rectifier filter circuit, optical feedback coupling, the peak voltage absorbing circuit and the like. This will not only improve the efficiency and accuracy of the circuit, but also improve the stability and security of the circuit.

目录

1 绪论

1.1 开关变换器的起源...........................................................................................................1

1.2 开关变换器的发展趋势...................................................................................................1

2 反激式开关变换器简介..............................................................................................................2

2.1 开关变换器的主要分类...................................................................................................3

2.2 反激式开关变换器原理...................................................................................................3

2.3 反激式变换器的工作方式...............................................................................................3

2.3.1 连续导电模式..........................................................................................................3

2.3.2 断续导电模式..........................................................................................................4

3反激式开关变换器系统规划与设计...........................................................................................4

3.1 反激式开关变换器子电路简介.......................................................................................4

3.2 输入端电路的设计...........................................................................................................5

3.2.1输入电路的设计.......................................................................................................5

3.2.2变压器的设计...........................................................................................................8

3.2.3输出二极管的选取..................................................................................................12

4 SiC MOSFET、WPM控制电路和反馈电路设计.........................................................................14

4.1碳化硅MOSFET...............................................................................................................14

4.2 UC3845 PWM电路...........................................................................................................15

4.3电压采样光耦合反馈电路...............................................................................................15

5仿真电路的搭建与Multisim仿真..............................................................................................16

5.1 Multisim软件介绍............................................................................................................16

5.2电路仿真图.......................................................................................................................17

5.3仿真结果...........................................................................................................................17

总结.................................................................................................................................................19

参考文献.........................................................................................................................................20

第一章 绪论

1.1开关变换器的起源

早期的电子元件多由晶体管构成，在开关变换器产生之前，电源的稳压器件是靠晶体管并联构成的线性稳压电源实现的。在传统的技术当中，这种稳压器件可以得到连续控制的线性稳压电源，技术比较成熟，且器件性能具有稳定，输出波纹小等优点。 但是如同其他晶体管器件一样，晶体管的大体积，和笨重的重量，使得这种传统的稳压电源体积巨大且重量较重，致使其无法满足在越来越小、越来越灵活的各类小型家用电子器件中的使用。

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