Power-transfer of isolated converter with integrated power sharing for LED-lighting system dependent on transformer coupling

An isolated power converter topology is presented which uses an integrated passive power-sharing network for equal brightness levels in parallel LED branches. Analyses show the dependency of the power sharing quality on transformer tolerances and highlight the influence of transformer leakage inductances on the achievable power transfer of the topology. An optimum design for minimum switch current stress at given leakage inductances is presented. A full size prototype operating from the 230 V mains supply and achieving a luminous flux of above 7000 lumens has been built and tested. Experimental results of power transfer and power sharing are in good correlation with theoretical predictions.