基于单片机的电子负载的设计.doc

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负控制环路控制环路电路的核心实质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。从而达到电子负载的恒流控制ABSTRACT The principle of electronic load is control of transistors inside power MOSFET or the guide flux of power tube, it is a consumption power equipment which depends on the dissipation power of tube, there are four basic working ways that persistence pressure, constant current, the constant resistance, constant power . This design start with the analysis of DC electric load system solutions, it discussed 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 realized 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 essences are the op-amp, MOS tube here both as a control device and as a power load tested. Controlling 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 realized constant current work pattern. This design can realize the Constant-current control of the electronic load: it can measured the current, voltage and power of Measured power and the LCD display. If it use situations in rated, no matter how the input voltage change in the constant-current mode (within a certain range), the electronic load will be based on setting to absorb the current, the current which flows the electronic load will constant. Key words: electronic load; constant-current pattern; PI adjuster; AD transform; DA conversion 目 录 绪 论 1 第一章