The Design Of A Digital High-power Constant Current Source Circuit Used In Detection

With the development of electric power industry, there is a growing demand for the level of technique of automatic detection devices applied in the reliability detection of electronic components in networks of electric power transmission and distribution. Precision and stability of experimental power source is the guarantee of the quality of products. Currently, many experimental electronic detection devices have been developed by oversea enterprises to be applied in the testing of electronic products in order to meet the national or international standards. However, most of these products are deficient in precision, level of output power and involvement of computerized control techniques and thus unable to meet the requirement of detection. Techniques of producing small direct current, small output constant current power sources are mature; In contrast, research on developing highly stable large output current and power constant current source is still ongoing. The purpose of this paper is to design a highly stable digitalized constant current power source with high current and power output based on the principles of closed-loop control system and techniques of embedded system.This paper first introduced the worldwide contemporary techniques of detection devices ensuring electronic products reliability and the future development, present development of experimental constant current techniques and the demand for highly stable, digitalized constant current power source with high current and power output due to the future development of information technologies. Upon summarizing the current techniques, this paper determined that "the design of a digitalized constant current power source system with large output power applied in circuit detection" should focus its research on how to design the detection circuit of the output current, adjustment and control module and human-machine interface platform. After the determination of the direction of research, several aspects of works listed as follow have been done.1. Designed and implemented a large current generator (2000VA) consists of current-rise transformer and electrodynamic autotransformer, which, through controlling the electric motor, can vary the adjustable coil end of the autotransformer and thus can adjust the current output smoothly from 0A to 350A.2. Designed and implemented detection circuit of the output current. The circuit adopted the precision absolute-valve technology and completely overcame the intrinsic detection blind zone of common diodeabsolute-valve circuit, achieved good performance when the circuit is at low level signal area. The precision of measurement reached 1%.