Delta three-phase, 12.5kW digitally controlled power factor corrector: Design challenges and solutions for high efficiency and low total harmonic distortion performance

High efficiency and low Total Harmonic Distortion (THD) rectifiers have become a standard in the telecom industry. This paper describes the development of a digitally controlled Delta three-phase PFC to meet this standard. One way of improving efficiency is to reduce switching losses of the switching devices. This reduction could be achieved by modulation of the control output. This paper analyzes different modulation schemes and gives recommendation based on test results. One of the challenges during development is the control of cross-coupled three phases. The most common control method is to transform three phases into two degrees of freedom orthogonal space using α-β or d-q transformations. This paper compares both transformations through simulation results. The design, simulation and hardware test results demonstrating achievements of design goals in efficiency and THD are presented in this paper.