DC/DC Conversion System with Digital Control

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Supervisor:
Dr. Hamar János Krisztián
Department of Automation and Applied Informatics

The final project focuses on designing a converter capable of supplying various low power consumer electronics devices in the 3 to 25 Volts range, up to 200 Watts output power. First, different topologies are analyzed based on literature, to select the suitable one for the application. The operation of the selected converter is analyzed with emphasis on the unique behavior of the selected topology and how it can be modeled. The results of two models are presented, a large-signal model describing steady-state operation and a small-signal model that describes transient behavior. These models are used to work out a well-founded selection of power stage components, as well as to design a control loop employing digital voltage-mode control. Although the project focuses on the DC/DC conversion in the system, an input rectifier filter is designed with an inrush current limiting circuit that supplies the DC/DC converter input. The operation of the designed converter is simulated in LTSpice, the fulfillment of design targets is verified and simulation results are presented that can be compared to measurements. The concept of intelligent load units is explicated and a solution is presented. The control and sensing circuitry of the converter is designed, then the schematic and PCB layout of the converter is created in KiCad. The first prototype of the converter was manufactured. Prototype measurements are set up, an additional design procedure is carried out based on the measurements and the sensing circuitry is evaluated. The converter is tested with open-loop control, the simulation and measurement results are compared and improvements are suggested. Finally, conclusions are drawn based on the accomplished results.

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