Improving the Performance of Single Phase Power Factor Correction Circuit using Parallel Boost Converters.

The equipment connected to an electricity distribution network usually needs some kind of power conditioning, typically rectification, which produces a non-sinusoidal line current due to the nonlinear input characteristic. With the steadily increasing use of such equipment, line current harmonics have become a significant problem. Among the various PFC technique’s we will get better power factor by using high-frequency active PFC circuit. Any DC-DC converters can be used for this purpose, if a suitable control method is used to shape its input current or if it has inherent PFC properties. Also, there exist several advantages to parallel-connected DC-DC converters, including increased reliability, decreased stress on critical components, improved efficiency, and more flexibility. In this project, a control technique for parallel-connected boost converter is proposed. This is an active-control scheme in which we force the current in one converter to follow that of the other. This approach is based on phase shifting of two boost converters connected in parallel and working at the same switching frequency. The PI controller is used to reshape the input current so as to reduce the harmonics. The input EMI filter is inserted in the proposed strategy so as to reduce the effects of switching harmonics. The ac modelling of the boost converter is done and the line-to-output, the control-to-output transfer functions are evaluated according to which stability analysis is done utilizing the Bode plot criteria.