Magnetic flux density bias analysis and suppression strategy for voltage-fed single-stage full-bridge converter

Power transformer in the voltage-fed single-stage full-bridge (SSFB) converter is easy to be saturated because of the special operating mode of this topology. First and foremost, detailed analysis about the generation mechanism of the transformer saturation in the voltage-fed SSFB converter is presented for the first time in this paper. Second, the mathematical expression of the maximum value of magnetic flux density bias (MFDB) during every line cycle is deduced. Furthermore, a novel suppressing strategy, consisted of the digital compensating algorithm and design considerations, is proposed based on the theoretical analysis and mathematical expression. The MFDB can be eliminated and additional circuits are not needed with the proposed strategy. Finally, a 1kW prototype with the voltage-fed SSFB topology is built to verify the effect of the proposed approach. The voltage-second imbalance is reduced to less than 1% using the proposed suppression strategy compared with 14% when the strategy is not used. Consequently, the system reliability and the efficiency are improved. Copyright (c) 2016 John Wiley & Sons, Ltd.