摘 要

随着光伏发电和风力发电的需求逐渐增大，电力电子装置需要大量投入到如山区、海上、旷野等各种复杂环境，由于此类环境中的温度、湿度变化较大，且难以检修，因此对电力电子装置的可靠性提出了更高的要求。为帮助解决以上问题，本设计旨在提出一种低成本高可靠性Buck变换器的电路设计，Buck变换器为最基本最经典的拓扑之一，其结构和工作原理相对简单，且同步Buck变换器中的半桥结构也是各种拓扑中的最基本单元，具有广泛代表性。

本文首先调研了提高电路可靠性的各类方法，拟从器件选择、电路设计、热设计等三个方面入手，提高变换器的可靠性。而后通过分析Buck变换器的工作原理，选择了同步半桥的电路结构，该结构减小了续流导通损耗，且提供了反向电流通路，在合理的工作模式下实现了软开关。在热设计过程中，为了不使用风扇散热，选择了多管并联结构，又为了不使用电解电容，选择了提高开关频率，从而选定了耐高结温、体二极管性能优异、开关损耗极低的SiC MOSFET。但是在SiC MOSFET多管并联时，又面临着串扰和不均流等问题，本文又选择了三极管主动钳位、“近细远粗”布线等低成本方法来解决。同时还选择了使用空心电感，以减小铁损增大磁饱和裕量。最终，通过双脉冲实验，功率实验，温度-时间实验等，对本文提出的一系列设计进行了有效验证。

本文的SiC MOSFET多管并联半桥结构广泛的应用在种大功率变换器中，而针对其面临的串扰和均流等问题提出的解决办法则具有重要意义。

关键词：高可靠性；同步Buck；多管并联；串扰

Abstract

With the increasing demand for photovoltaic power generation and wind power generation, power electronic devices need to be heavily invested in various complex environments such as mountains, seas, and wilderness. Since the temperature and humidity in such environments vary greatly, and it is difficult to overhaul, the power electronic devices need to be heavily invested. The higher requirements are placed on the reliability of power electronic devices. To help solve the above problems, this design aims to propose a circuit design for a low-cost, high-reliability buck converter. Buck converter is one of the most basic and classic topologies. Its structure and working principle are relatively simple, and synchronous buck conversion The half-bridge structure in the device is also the most basic unit in various topologies and is widely representative.

This article first investigated various methods to improve the reliability of the circuit, starting from the three aspects of device selection, circuit design, thermal design and improve the reliability of the converter. Then, by analyzing the working principle of the buck converter, the circuit structure of the synchronous half-bridge is selected. This structure reduces the free-wheeling conduction loss, and provides a reverse current path. In a reasonable mode of operation, soft switching is realized. In the thermal design process, in order to avoid fan heat dissipation, a multi-pipe parallel configuration was selected, and in order not to use an electrolytic capacitor, the switching frequency was selected so that the high junction temperature resistance, excellent body diode performance, and low switching loss were selected. SiC MOSFET. However, when SiC MOSFETs are connected in parallel in multiple tubes, they are faced with problems such as crosstalk and non-uniform current. This paper also selects low-cost methods such as triode active clamping and "near-thin and coarse-rough" wiring.

The multi-tube parallel half-bridge structure of SiC MOSFET in this paper is widely used in high-power converters, and the solution proposed for cross-talk and current sharing is of great significance.

Key Words：High reliability; Synchronous Buck; Multiple parallel connections; Crosstalk

目录

摘 要 I

Abstract II

第1章 绪论 1

1.1引言 1

1.2技术背景的研究：提高可靠性的方法 1

1.2.1从器件选择上提高可靠性 2

1.2.2从电路设计上提高可靠性 2

1.2.3从热设计上提高可靠性 2

1.3本设计的目的及意义 3

第2章 Buck电路主功率的设计 4

2.1 Buck变换器的工作原理 4

2.1.1降压原理 4

2.1.2工作模式 5

2.2同步半桥结构 8

2.2.1用场效应管替代二极管 8

2.2.2死区时间的产生与二极管续流 8

2.2.3增大电流纹波实现软开关 9

2.2.4软开关调高效率的适用范围 10

2.2.5 BCM模式实现软开关的关键参数计算 11

2.3 Buck变换器的多管并联结构 13

2.3.1无风扇散热系统 13

2.3.2多管并联的半桥结构 13

2.3.3多管并联的散热系统 13

2.3.4多管并联的半桥回路优化 14

2.4 Buck变换器的器件选择 16

2.4.1电容器件的选择 16

2.4.2半导体器件的选择 16

2.4.3电抗器件的选择 18

第3章 驱动电路的设计 20

3.1 SiC MOSFET半桥结构的串扰问题 20

3.2本设计中串扰问题带来的挑战 22

3.3本设计中对解决串扰问题的设计 23

3.4均流电路的设计 24

第4章 无源元件的设计 25

4.1电抗器的设计 25

4.1.1电感量的计算 25

4.1.2匝数的计算 25

4.2电容器的设计 27

4.2.1滤波器电容参数计算 27

4.2.2母线电容的计算 27

4.3参数仿真 27

第5章 实验验证及结果分析 29

5.1样机简介 29

5.2双脉冲测试 29

5.2.1单管测试 29

5.2.2动态均流性能测试 31

5.3功率-温度测试 31

5.4结果分析 32

5.5不足与展望 32

第6章 总结 33

参考文献 34

致谢 36

第1章 绪论

1.1引言

随着人类对能源的需求日益增加，化石能源的逐渐枯竭，新能源发电成为发展趋势。太阳能、风能等新能源以其可再生、清洁无污染的特点逐渐受到人们的关注^[1]。在光伏发电和风力发电系统中，电力电子系统是其中最为关键的环节，但往往因其承受较大的电压电流应力、较高的开关频率，也是整个发电系统中可靠性最低的部分^[2]。