Study And Design Of Digital Controller For DC-DC Converter

With the development of digital signal processing technique, the digital control technique is widely applied in DC-DC power converters. The digital controller can realize some complicated control strategies, it has higher reliability,stability and flexibility. At present, the conventional control strategies of switching mode power supply has MCU based controller,DSP based controller and FPGA based controller. In the MCU-based control mode, the control precision and the switching frequency is not high, and in the DSP and FPGA-based control mode, the control costs higher though the control precision is improved,and these core controllers are not the dedicated controller for the switching mode power supply. Therefore, it is necessary to design a dedicated digital controller for switching power supply, and the structure of the dedicated digital controller is simpler, the cost is lower.This paper research that the design and realize of the dedicated digital controller for DC-DC power converters, the research focus on the realize of the digital PID control algorithm and the design of the digital PWM generator, digital PID algorithm achieve by discrete the continuous domain of PID control algorithm, compensation link is controlled by digital PID compensator algorithm, the system bandwidth, phase and system response speed are improved, the output ripple amplitude is reduced; Consider the hardware area, switching frequency, resolution and accuracy factors, the digital PWM implement by count compared with delayed of hybrid mode, and on the digital dither is joined, the delay link implement by closed-loop, better achieved on the clock frequency and area of the expedient, and improved the effective resolution of digital PWM without increasing the hardware resources, it is a new realization for digital PWM.In this paper, the realization of digital controller in buck-type DC-DC converter has been verified, the experimental result of output voltage of the converter is stable, the ripple coefficient meet the design requirement, and dynamic response is rapid, achieve the design targets.