Design And Implementation Of AC Constant Current Source Based On Embedded System

With the development of electronic technology, the application of electronic equipment has been extended to various industries and fields, and the performance of the electronic equipment power supply has great influence on the accuracy, stability and service life of electronic equipment. Therefore, people are concerned about the development of power technology more and more. The system aims at the designing and development of constant current source for industrial use, realizes the feedback type high current constant current source controlled by microprocessor, it has the characteristics of accurate control, stable output current and low cost, etc. The successful development of the power supply has a certain practical significance for the further application of electronic equipment.The system is based on closed-loop control theory, takes embedded system control technology as the core, adopts electric energy conversion AC-DC-AC to implement a feedback type AC constant current source system with large current and high stability, then displays the real-time output current and the value of the keyboard input current on the LCD. This system realizes SPWM inversion technology based on the asymmetric rule sampling method and the mixed table lookup though internal program of TMS320F2812, which gives a real-time calculation and output of pulse control signal SPWM with corresponding width, drive the switching devices in the IPM module work after the isolation amplifier, inverts the output DC of AC-DC rectifier circuit module into AC, and supplies to the load through the LC filter circuit. It uses the current transformer for current feedback sampling, places sampling current signal into the sampling port of TMS320F2812 through conditioning circuit, adjusts PI algorithm according to the feedback of sampling current value and the difference between the values given by keyboard to get a large real-time AC output current accurately and stably by changing the pulse width of SPWM control signal according to the adjustment result of algorithm. The result of debug and test show that the effective combination of SPWM inverter technology, PI control technology and embedded technology can achieve the purposes of stable output 0-50A quasi continuous adjustable AC current, and the output current error can be controlled within a certain range.The system designs an AC constant current source with high current based on embedded system, which has an advantage of good stability, low cost, simple structure, large output current, etc. The result of theoretical research, design principles and experimental testing shows that the system has achieved the requirements of the design purposes, it lays a foundation for the further development of high-current feedback AC current source.