It is necessary to design a dc electronic load which can realize two modes of constant voltage and constant current and can be switched, and the voltage value and current value can be adjusted within a certain range. In this experiment, the two modes are switched manually.

 

500kw load bank
 

The two working modes of constant voltage and constant current are realized by the circuit composed of operational amplifier and feedback network. The feedback network in the circuit is based on field effect transistor, and the adjustable amplifier circuit is composed and supplemented by soft start circuit and voltage compensation circuit. Adjustable amplifier circuit also refers to the amplifier circuit according to the output requirements, through the feedback circuit to change the feedback signal, to meet the output requirements.

Soft start circuit can gradually increase the voltage from zero to rated voltage, so that the starting current of the circuit changes from uncontrollable overload surge current to controllable in the starting process.

Voltage compensation circuit is power factor compensation. Current through the electronic load consumes some of the energy, so the end result is very different from the expected value, and the voltage compensation circuit can compensate for the loss.