Application of series resonant converters to reduce ripple transmission to LED arrays in offline drivers

Proposed is a novel approach to reduce low-frequency ripple in light-emitting diode (LED) arrays that are supplied from the AC grid. The proposal employs a series resonant DC-DC converter connected to the output of the power factor correction (PFC) stage so that the low-frequency ripple transmitted from the PFC stage to the LEDs can be minimised. This solution achieves two goals: (i) reduction of the bulk capacitance used at the output of the PFC stage so that long-life film capacitors can be employed, and (ii) increasing the efficiency of the LED driver owing to the low switching losses of the resonant converter. Experimental results are provided to validate this proposal.