论文题目：简易直流电子负载（硬件） 专 业：自动化
学 生：方 威 签名：＿＿＿＿ 指导教师：柴 钰 签名：＿＿＿＿
摘 要
本系统是以MSP430F5438控制器为核心设计的一个简易直流电子负载。该设计采用了MOSFET作为主回路开关管，以12位D/A转换器及运算放大器作为MOSFET的驱动电路，配以高精度采样电路及16位A/D转换器作为数字反馈控制，完成了单片机对输出电流的实时检测和实时控制，实现了100mA～1000mA范围内分辨率小于10mA恒定电流控制的功能，并保证了负载两端电压变化大的情况下，电流恒定的效果。对电流电压的测量具有较高的精度与稳定性，同时具备负载调整率自动测量功能。人机接口采用触摸屏及LCD液晶显示器，控制界面直观、简洁，具有良好的人机交互性能。
关键词：电子负载；MOSFET；MSP430F5438；恒流控制；负载调整率 论文类型：应用型
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Title: A simple DC electronic load (hardware) Major: Automation Name: Fang Wei
Signature: ____________
Supervisor: Chai Yu Signature: ____________
ABSTRACT
The simple DC electronic load core system is based on MSP430F5438 controller. The design uses MOSFET as the switch tube in major loop , with 12 bit D/A converter and amplifier as the driving circuit of MOSFET, with high precision and sampling circuit and a 16 bit A/D converter for digital feedback control, the real-time detection of the output current of the MCU and real-time control system, realizes the 100mA ~ 1000mA range resolution of less than 10mA constant current control function, and to ensure that the voltage across the load change under the condition of large, constant current effect. The measurement of the voltage and current are precision with high stability. At the same time the simple DC electronic load core can automatic measure the load regulation. Man-machine interface using touch screen and LCD liquid crystal display, intuitive control interface, concise, has good performance of human-computer interaction.
Key word: Electronic load; MOSFET; MSP430F5438; Constant current regulation; the load
regulation
Type of Thesis： Applied
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目 录
1 绪 论 ................................................................................................................................................................... 1 1.1 直流电子负载的发展 ................................................................................................................................... 1 1.2 研究直流电子负载目的和意义 ................................................................................................................... 1 1.3 本设计的功能和指标 ................................................................................................................................... 2 2 系统方案分析和设计 ............................................................................................................................................ 3 2.1 简易直流电子负载的系统设计 ................................................................................................................... 3 2.2 简易直流电子负载的系统方案 ................................................................................................................... 3 2.2.1 主回路控制设计方案 ........................................................................................................................... 3 2.2.2 恒流电路设计方案 ............................................................................................................................... 4 2.3 简易直流电子负载的系统分析 ................................................................................................................... 4 2.3.1 恒流系统分析 ....................................................................................................................................... 4 2.3.2 测量系统分析 ....................................................................................................................................... 5 3 系统电路设计........................................................................................................................................................ 7 3.1 系统主回路设计 ........................................................................................................................................... 7 3.1.1 MOSFET简介 ....................................................................................................................................... 7 3.1.2 以IRFP450为核心的系统主回路 ....................................................................................................... 7 3.1.3 TLV5618简介 ....................................................................................................................................... 8 3.1.4 以TLV5618为核心的MOSFET驱动电路......................................................................................... 9 3.2 电流电压采集电路 ....................................................................................................................................... 9 3.2.1 OPA228简介 ......................................................................................................................................... 9 3.2.2 以OPA228为核心的电流电压变换电路 .......................................................................................... 10 3.3.3 ADS1115简介 ..................................................................................................................................... 12 3.2.4 以ADS1115为核心电压采集电路 .................................................................................................... 12 3.4 保护电路设计 ............................................................................................................................................. 12 3.5 主控制器及人机交互部分的设计.............................................................................................................. 13 3.5.1 MSP430单片机简介 .......................................................................................................................... 14 3.5.1.1 MSP430单片机的特点 ................................................................................................................... 14 3.5.1.2 MSP430单片机的主要应用............................................................................................................ 15 3.5.1.3 MSP430单片机的功能部件............................................................................................................ 16 3.5.2 液晶显示屏简介 ................................................................................................................................. 17 3.5.3 触摸屏简介 ......................................................................................................................................... 18 3.5.4 主控制器与人机交互电路 ................................................................................................................. 19 4 系统测试及结果分析 .......................................................................................................................................... 21 4.1 测试仪器 ..................................................................................................................................................... 21 4.2 测试方法、测试结果及分析 ..................................................................................................................... 21 4.2.1 电压测试方法及结果 ......................................................................................................................... 21 4.2.2 电流测试方法及结果 ......................................................................................................................... 22
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4.2.3 负载调整率测试方法及结果.............................................................................................................. 22 4.2.4 电流调节器效果测试方法及结果 ...................................................................................................... 23 4.2.5 数据测试结果分析 ............................................................................................................................. 24 4.3 误差原因分析 ............................................................................................................................................... 27 4.3.1 主要误差原因 ..................................................................................................................................... 27 4.3.2 其他可能引起误差的原因 ................................................................................................................. 27 5 结 论 ............................................................................................................................................................... 28 致 谢 ..................................................................................................................................................................... 29 参考文献 ................................................................................................................................................................. 30 附 录 ..................................................................................................................................................................... 31 附录A：系统整体电路原理图 .......................................................................................................................... 31 附录B：MSP430F5438单片机最小系统实物图 ............................................................................................. 32 附录C：整体电路实物照片 .............................................................................................................................. 33
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