A power quality improved bridgeless converter based computer power supply

Poor power quality, slow dynamic response, reduced output voltage regulation, high device stress, harmonic rich, periodically dense, peaky, distorted input current are the major problems which are frequently encountered in conventional switched mode power supplies (SMPSs) used in computers. To mitigate these problems, it is proposed here to use a non-isolated bridgeless buck-boost single ended primary inductance converter (SEPIC) in discontinuous conduction mode (DCM) at the front end of an SMPS. The bridgeless SEPIC at the front end provides stiffly regulated output dc voltage even under frequent input voltage variations and loads. The output of the front end converter is connected to a half bridge dc-dc converter for isolation and also for obtaining different dc voltage levels at the output that are needed in a computer. Controlling a single output voltage is able to regulate all the other dc output voltages as well. The design and simulation of the proposed power supply is carried out for obtaining improved power quality which is verified through the experimental results.