Design of a high switching frequency interleaved step-up converter with digital interface for Power Factor Correction applications

Abstract

Power Factor Correction (PFC) circuits can be used to mitigate problems with harmonics associated with rectifying AC to drive a DC load. A two channel step-up converter with correctly controlled switches can be used as a PFC. High frequency switching gives the advantage of physically small boost stage inductors and filters. The purpose of this thesis was to investigate the possibilities of utilizing high switching frequencies while maintaining a high efficiency. A short literature study about the subject was made which was followed by component choices based upon the studies and relating calculations. This was succeeded by the design and manufacturing of a circuit board. All surface mounted components were attached and the verification of the circuit was carried out by systematically mounting the remaining through hole components and writing testing software. Performance evaluation was the last thing to be done. The main result is a working dual channel step-up converter capable of providing 1 kW at 400 V using 1 MHz switching frequency, however at the expense of the efficiency which dropped to just above 94 %. More work, especially software related work, is needed before the device can be used as a PFC and there are also possible improvements that can be implemented in order to increase the efficiency. Given that the switching frequency aimed for was reached and that there are possible improvements to the efficiency, smaller boost stage inductors and filter components are possible which can increase the power density of devices utilizing PFCs.