The Study Of Digital Control Switching Power Supply Based On Si825x

Digital control technology becomes more and more popular in the field of switching-mode power supplies. Compared with analog controllers, digital controllers have many advantages. The digital controller can realize some complicated control strategies and has higher reliability and stability, and the design of the digital controller is flexible. The digital controller can realize the intelligent power and reduce the design cycle of new products.In this paper, the digital control's characteristics, advantages and the current market situation were introduced at first, the challenges of the digital control faced in use was pointed out. An in-depth study on the digital control technology of power supply was accomplished, such as the influence of sampling holding and delay, the design method of digital compensator, digital control strategy, digital control algorithm, how to improve the accuracy of the power supply and other main questions which existed in digital control system.In this paper, the DC/DC converter mathematics model was discussed by calculated the hardware parameters of half-bridge circuit. And then the digital compensator was modeled and simulated by Si825x Application Builder and MATLAB. Digital PID algorithm plays an important role in digital control of the power supply. Based on digital PID, the experts PID control was applied in the digital power supplies control system in this paper. The simulation results showed that the expert PID control was smaller than conventional PID control in overshoot and the period of adjustment. The expert PID control has improved the dynamic performance and anti-jamming capabilities of the control system. It has a higher stability than conventional PID. Therefore, this control mode was very suitable for the DC/DC converter which required relatively higher occasions in dynamic performance.In order to verify this control strategy, the author applied it to a set of 270 W medical power supply. The control circuit was based on Silabs's Si825x, the half-bridge converter as power circuit, the digital control and digital management was implemented on the medical power supply.