Power factor corrected SMPS using Sheppard-Taylor converter

Conventional switched mode power supplies (SMPSs) used in personal computers (PCs) are suffering from various power quality (PQ) problems such as high crest factor (CF), distorted and dense periodic input ac mains current with very low power factor (PF) and poor output voltage regulation. A non-isolated Sheppard-Taylor (S-T) converter in SMPS is proposed to mitigate these PQ problems and to maintain constant multiple dc output voltages. The non-isolated S-T converter operates in discontinuous conduction mode (DCM) to achieve input power factor correction (PFC). It results in improved PQ making the input ac mains current sinusoidal even under varying supply voltages and loads while meeting the guidelines on harmonic emissions of international standard. The design and modeling of such an SMPS system are presented here along with simulation results corroborating its improved performance in terms of low supply current harmonics, less switching device stresses, high PF and excellent output voltage regulation.