文档介绍：摘要电子负载的原理是控制内功率 MOSFET 或晶体管的导通量,靠功率管的耗散功率消耗电能的设备,它的基本工作方式有恒压、恒流、恒阻、恒功率这几种。本设计从直流电子负载系统方案分析入手,详细讨论了整个系统的硬件电路和软件实现,并给出较为合理的解决方案。为便于控制的实现和功能的扩展,采用了 STC89C52 单片机作为核心控制器,设计了 DA输出控制电路、AD电压电流检测电路、键盘电路、显示电路和驱动电路,通过软、硬件的协调配合,实现了整个设计。通过运放、PI调节器及负反馈控制环路来控制 MOSFET 的栅极电压,从而达到其内阻变化。这个控制环路是整个电路的核心实质,MOS 管在这里既作为电流的控制器件同时也作为被测电源的负载。控制 MOS 管的导通量,其内阻发生相应的变化,从而达到流过该电子负载的电流恒定,实现恒流工作模式。本设计能实现电子负载的恒流控制:能够检测被测电源的电流、电压及功率并由液晶显示。在额定使用环境下,恒流方式时不论输入电压如何变化(在一定范围内), 电子负载将根据设定值来吸收电流,流过该电子负载的电流恒定。关键词:电子负载; 恒流模式; PI调节器; AD转换; DA转换毕业论文(论文) ABSTRACT ABSTRACT The principle of electronic load is control of transistors inside power MOSFET or the guide flux of power tube, it isa consumption power equipment which depends on the dissipation power of tube , there are four basic working way s that persistence pressure, constant current, the constant resistance, constant power . This design start with the analysis of DC electric load system solutions, itd iscussed the realization of the whole system hardware circuit and software in detail , and give a reasonable solution. In order to realize the control and the expansion of function conveniently , we adopted the STC89C52 microcontroller as the core controller, and designed the DA output control circuit, AD voltage current detection circuit, keyboard circuit, display circuit and drive circuit, through the coordination between hardware and software, finally, we realize d the whole design. PI adjuster and negative feedback control loop of the circuit which control the grid voltage of MOSFET, so as to change its resistance. The core essence s are the op-amp, MOS tube here both asa control device and asa power load tested. Control ling the guide flux of the MOS tube, the resistance of the MOS tube will change accordingly , thus the current which flows the electronic load current will constant, At last, we realize d constant current work pattern. This design can realize the Constant-current control of the electronic load: it can measured the current, voltage and po