A simple control algorithm to avoid flux density bias in isolated full-bridge topologies

Isolated full-bridge topologies are used in some industrial applications due to its characteristic of cost-effective and high power density. However, the transformer used for isolation in such topologies can be easily saturated. In this paper, a control algorithm to suppress flux density bias in the transformer is proposed. The algorithm can be easily implemented into a low cost DSP. Details of the practical implementation of the proposed algorithm are shown. An example of application over a 3 kW single-stage power factor corrector is presented. The experimental results illustrate the feasibility of the proposed digital control solution.