Graduation thesis of electronic load based on microcontroller (including schematic diagram + program)

The principle of electronic load is to control the conduction of internal power MOSFET or transistor, and it is a device that consumes electric energy by dissipating power of power tube. Its basic working methods include constant voltage, constant current, constant resistance and constant power.
This design starts from the analysis of the DC electronic load system solution, discusses the hardware circuit and software implementation of the entire system in detail, and gives a more reasonable solution. In order to facilitate the realization of control and expansion of functions, the STC89C52 microcontroller is used as the core controller, and the DA output control circuit, AD voltage and current detection circuit, keyboard circuit, display circuit and drive circuit are designed. Through the coordination of software and hardware, the the entire design. The gate voltage of the MOSFET is controlled through the operational amplifier, PI regulator and negative feedback control loop, thereby achieving changes in its internal resistance. This control loop is the core essence of the entire circuit. The MOS tube here serves as both a current control device and a load for the power supply under test. By controlling the conduction of the MOS tube, its internal resistance changes accordingly, thereby achieving a constant current flowing through the electronic load and achieving a constant current working mode.
This design can realize constant current control of electronic loads: it can detect the current, voltage and power of the power supply under test and display it on the liquid crystal. Under the rated usage environment, in constant current mode, no matter how the input voltage changes (within a certain range), the electronic load will absorb current according to the set value, and the current flowing through the electronic load will be constant.