Design of an integrated SEPIC and Buck Converter for High Step-down Applications

Abstract

To overcome the issues related to special power supply called voltage regulator module (VRM) used for microprocessors, a special DC-DC converter will be designed in this work in which single-ended primary inductor (SEPIC) converter and the inverted form of buck converter are combine. As per available literature the problems associated with conventional VRM’s are slow transient response and narrow duty cycle. Other issue related to the voltage regulator module is the high voltage stress that occurs on switches of VRM. The solution to these problems is presented in the form of a new proposed dc-dc converter topology in which the single ended primary inductor is combined with the inverted form of buck converter. The proposed topology has the advantages of reducing the transient time at moderate duty cycle because of the parallel combination of the inductor. Similarly, the parallel combination of capacitor will step down the voltage from 12v to the appropriate voltage level required for the microprocessor. The steady state operation and transient state operation of the proposed VRM is discussed in this thesis. Various operating states of proposed converter are discussed and related equations for voltage gain, voltage stress and transient response have been derived. Output waveforms are plotted, and mathematical modeling is carried out. Simulation results for proposed and conventional VRM are obtained and from comparison of results, it is clear that proposed VRM is good in performances compared to conventional VRM’s.