P.F. improvement technique in SPC

Static power converters are major examples of both nonlinear loads and one that shift the phase relationship between the voltage and current. Hence each generation of linearitystatic power converter is need to address the problems of non-linearity (i.e. harmonics) and var requirement or relationship between voltage and current i.e. phase relations or power factor. The present generations of SPC uses line commutations for rectifier. The voltages of D.C. link are controlled by phase control devices used for converter. MOSFETs are good for these purposes. For lower DC voltage needs the delay in a conduction of current, i.e. delay angle ´´a´´ increases, the angle between voltage and current & worsens the P.F. For compensating this there is increment in capacitive VAR requirement. A P.F. improvement technique in SPC discussed in this paper is having the basic reference of the delay angle control. The improvement in input power factor in SPC is achieved by varying symmetrical angle ´´thetas´´ from pi/2 to 0 or conduction angle ´´beta´´ from 0 to pi. i.e. symmetrical angle control method and extinction control method. Extinction angle control is by controlling extinction angle ´´gamma´´ from pi to 0.The input power factor get improved by the input current phase gets shifted in phase with input voltage.