High-frequency ZVS Ćuk converter for automotive LED driver applications using planar integrated magnetics

Abstract

This paper presents a high-frequency zero voltage switching (ZVS) (Cuk converter using planar integrated magnetics. The converter is intended for automotive LED driver applications. The converter switching frequency is above the AM frequency band to reduce radio frequency interference. The input inductor, the output inductor, and the transformer are realized on a single planar integrated magnetic structure, resulting in low input and output current ripples and reduced EMI. The planar integrated magnetics structure is optimized using 3D finite element method (FEM) tools. The transformer leakage inductance is minimized to eliminate the need for snubbers, while the magnetizing inductance is selected to achieve zero voltage switching (ZVS) over a wide range of operating points. Experimental 1.8 MHz-to-2.4 MHz Cuk converter prototypes are constructed using Silicon MOSFETs or GaN transistors. The prototypes operate over an output voltage range from 3 V to 50 V, while supplying a constant 0.5 A output current to a string of 1-to-15 LEDs. Using Silicon MOSFETs, the prototype achieves a peak efficiency of 92.9%, while the GaN based prototype achieves a peak efficiency of 93.5%. Both prototypes maintain greater than 90% efficiency across a wide output voltage range.