Magnetic Integrated LLC Resonant Converter Based on Independent Inductance Winding

LLC resonant converter has the advantages of high frequency and high efficiency, and has been developed rapidly and widely used in recent years. However, due to the presence of multiple magnetic components in the circuit, the improvement of power density is limited. To solve this problem, integrated magnetic transformer is usually designed to replace the discrete magnetics. While, the leakage inductance of the transformer cannot be controlled, the loss of the converter increases. In this paper, a magnetic integrated LLC resonant converter with independent inductance winding is proposed. The resonant inductance and magnetizing inductance are integrated with the transformer in the same magnetic core by using the decoupling integration method. Compared with the existing solution of magnetic integrated LLC resonant converter, this method can reduce the leakage inductance between the transformer windings and decrease the magnetic saturation of the integrated magnetics, thereby reducing the magnetic core loss and improving the efficiency of the converter. Compared with the discrete magnetics, the volume and weight of the magnetic components are reduced by 25.68% and 43.82% respectively, making the power density of the converter effectively improved. Finally, an experimental prototype of integrated magnetic LLC resonant converter with operating frequency of 350kHz and output power of 400W is built. The experimental results verify the correctness of the design scheme.