Research On The Digital Control Algorithm To Improve The Transient Response Of Digital Power Buck Converter Rectification

The performance of power supply sits at the heart of electronic system, which exertstremendous influence on the accuracy, stability and liability of the operation of the system.With the relentless development of the IT technology, the ever-increasing demand for thepower supply device dwarfs the traditional analog power device since its intrinsic processdeviation, poor flexibility and inconvenience to integration. However, this problem has beensettled effectively by the digital power supply, for its high accuracy, flexibility,programmability and integration property, which naturally rises to a hotspot of the institutes’recent research, domestic and abroad alike. Admittedly, digital power supply techniqueprovides an effective method to settle various common issues in analog power devices, suchas inaccuracy, temperature deviation, drift and inability of compensation for nonlinearity. Thetime delay caused by complicate control loop leaves much to be desired in the speed ofresponse to external dynamic input. Accordingly, this paper gets a deeper insight into thisproblem and comes up with a proper method to improve the transient response of the digitalpower supply.In this paper, the basic principle of Buck converter is firstly introduced. It also discussesthe circuit devices’ impact on the transient response of power system, followed by analysis ofthe cause of the time delay. The control loop, in this paper, is divided into four parts: sampling,data processing, compensation control and DPWM generation. Still, the role of each part ontransient response of the power system is also discussed respectively, as well as the method toenhance the quality of transient response. To overcome the influence imposed by loop timedelay to system transient response, we draw comparisons and analysis between variousprediction plans. Coupled with the circuit structure, we also come up with a predictionmethod of delay compensation to predict the precise load voltage and inductance current aftera single or many periods. Thus the loop’s time delay can be compensated and, in this way, wedevelop the control method of self-adapted fuzzy PID from the precise prediction.Finally the digital controller devised in this paper has been verified and realized onSimulink simulation system and FPGA. It also weathered the final test in varied practicalsituation. It turns out: (1) The prediction method of time delay compensation obviously quickens the responseprocess, with overshooting dropping from30%to5%. The limit cycle phenomenon has alsobeen overcome.(2) The transient response of adaptive fuzzy PID control is more excellent than thecommon PID control. In the same transient conditions, the former is improved by16μscompared with the later.(3) The digital controller in the paper can achieve the stable output voltage during8switching periods when the output voltage is under2V.