Electronic load principle

Electronic load principle:

The basic working mode of electronic load (CC/CV) makes electronic load play a very important role in the design and production of power supply products. However, it still seems to be shrouded in mystery until now.

1. Constant current control of electronic load (Chinese name: constant current mode; English name: CC-Constant Current mode).. The core of the circuit is a current sampling negative feedback control loop, where transistor Q1 (2N3055) is used as both the current controller and the load of the power supply under test. The transistor Q2 (BC337) is the driving tube of Q1; The resistance R1 is a current-voltage conversion element (I/V converter). The voltage drop falling on R1 is compared with the reference source (Verf) through the voltage comparator IC1 to control the conduction and cut-off of Q2 and Q1, so as to achieve the goal of keeping the current constant.

2. Constant voltage control of electronic load (Chinese name: constant voltage mode; English name: CV-Constant Voltage mode). The circuit principle is shown in the figure below; The circuit principle of constant voltage mode is basically the same as that of current control.

The electronic load can simulate the load in the real environment (electrical appliances). It has the functions of constant current, constant resistance, constant voltage and constant power, as well as short circuit, overcurrent, dynamic, etc. It should be said that all power supply manufacturers will be useful and must have it. Electronic load is divided into DC electronic load and AC electronic load. Due to the application of electronic load, we usually say DC programmable electronic load.