A Study Of Nonlinear Algorithm For Improved Dynamic Response And DPID Compensation In Digitally Controlled DC-DC Buck Converter

Compared to analog controlled switching power supply, digitally controlledswitching power supply has the advantages of adaptable, programmable, shorter designcycle, easy to integrate and easy to manage. With the improvement of digital IC designtechnology, digital power supply gradually replace analog power supply in somehigh-technology applications, so as its increasing market. For the traditional digitallypower supply, analog signal input is sampled and converted by ADC, DPID plays therole of compensation, DPWM computes the duty cycle. In order to increase the dynamicresponse, nonlinear control algorithm is adopted. The frame of this thesis is as follows:The study is based on a dual-mode(PWM/PSM) switching digitally controlledpower supply, using mixed analog-digital IC design method. Then EDA software isadopted to the digital design process. In the end of Chapter2, quantization effect andlimit cycle effect are discussed.Main structure of digital power supply is proposed in the thesis, including ADC,DPWM, Soft-Start, Mode-Switch and Buck Circuit. Two operation modes(PWM/PSM),timing diagram and working state machines are given in the end.DPID design is introduced, including mathematical modeling, IIR filter design,automatic HDL code generation and the fixed-point number. Finally, post-simulationresults is presented, physical design is finished by EDA software.Nonlinear algorithms are introduced, including the principle and stability analysisof Charge Balance algorithm, Hysteretic Control algorithm and Nonlinear Gainalgorithm. From the load step transient simulation results, the digital power supply’sdynamic response is improved with2μs compared to linear control.In the end, system post-layout simulation results(including the simulation ofswitching power supply indicators), layout design and test results are presented.