Novel AC Driver and Protection Circuits with Dimming Control for Light Emitting Diodes

The purpose of this paper is to present AC driver and protection circuits of Light Emitting Diodes. For the presented circuits, AC power source can be applied to drive LED without further conversion stage and the circuits provide failure indication and protection. The presented system consists of a full-bridge LED modules, power device and control circuit for dimming control and protection circuits. The LED modules for each upper and low arm are with pulse-width modulation control in every half fundamental cycle. The indication and protection circuits activate whenever short circuit and open circuit of LED module occur. Moreover, the current path is switched off when short circuit of LED occurs. Experimental results derived from a test AC driven white LED lighting system are presented to fully confirming the function of performance of the proposed circuits.