The Design Of Digital DC-CC Converter Based On A New PID Algorithm

With the continuous development and widely used of mobile phones, laptops, smart watches and other electronic products, the requirements of power chips are increasingly high in these portable devices. Although traditional analog controlled power supply occupied the market for a long time in the past time, it becomes less able to meet the growing requirements of modern equipment because of its own inherent weaknesses. In contrast, digital power supply is to become a research hotspot in major universities and businesses.An appropriate digital compensation algorithm for Buck DC-DC converter with voltage feedback should be designed to improve the dynamic performance and stability of the output voltage. Then, an adaptive PID control algorithm and a new PID control algorithm based on the conventional digital PID algorithm are proposed in this thesis. The adaptive PID algorithm will adaptively adjust the values of Kp, K, and Kdaccording to the state of the output voltage; While the new PID algorithm is the combination of adaptive PID algorithm and Separation sampling PID algorithm, the AD-P control will be oversampled to further improve the dynamic performance of the system. According to the simulation results of these three control algorithm, it can be seen that the new PID algorithm is not only better than other two control algorithm on a linear transient response and load transient response, and it solves the excessive overshoot during the start-up.Finally, the thesis uses FPGA to build a digitally controlled DC-DC converter verification platform, and the three control algorithm are tested respectively. The results show that for DC-DC converter with switching frequency 1MHz and 3.6-5V input voltage, compared with the conventional PID algorithm and adaptive PID algorithm, when the load current charges 700mA, the load response time of new PID algorithm is reduced by 75% and 58%, and the overshoot were reduced by 45.9% and 41.7%, respectively. In addition, the input voltage regulation and load current regulation under the new PID algorithm is 1mV/V and 30.2u,V/mA, which improve the stability of the system.