A Novel Current Sharing Method For Multi-Module Llc Resonant Converters

A novel load current sharing method is proposed for multi-module LLC resonant converters in high power application in this paper. The paralleled system is controlled by the maximum current sharing method to achieve load sharing automatically. Moreover, a series inductor is connected to each LLC output side to restrain the current ripple of double switching frequency. The maximum current sharing method is more stable than master-slave control and will not increase complexity. Theoretical analysis of the stability of individual module is based on the envelope model. And the stability of parallel operation is analyzed according to interface stability method. The analysis of the series inductor is given under first harmonic approximation assumption. Finally, an experimental prototype of a 4.8kW multi-module LLC converter system with 100V input voltage and 540V output voltage was built and tested to verify the proposed scheme.