Design methodology of LLC converters based on simplified mode analysis for wide output range

In this paper, an LLC resonant converter design methodology for wide output voltage range based on simplified operation mode analysis is presented. A new method to calculate the magnetizing inductance is developed based on the LLC mode analysis, which can ensure soft-switching operation when a maximum constant output power is implemented. The parameters, resonant frequency, maximum frequency and dead time, are swept to achieve the optimal design. The proposed design procedure is simple to handle yet can achieve satisfactory performance and is applied to a 1 kW converter. The experimental results are given to verify this methodology.