This presentation introduces a robust surge protection technique based on small supercapacitors combined with traditional surge absorber devices such as metal oxide varistors (MOV) and bidirectional breakover diodes, combined with a coupled inductor. Main design challenge to overcome was the very low voltage rating of a supercapacitor, which makes it impossible to place across the live and the neutral of an AC power line. Second challenge was the very low AC impedance of a farads order supercapacitor which creates a short circuit, if placed across the live and neutral of a power source. Designers had to come up with a unique technique based on a couple inductor combined with a supercapacitor subcircuit and an MOV, to achieve endurance for repeated surges without significant degradation of the MOV’s life. Overall component count of this new technique was less than a traditional surge protector and it can withstand UL1449 3rd Ed test procedure without degradation of the MOV life. Application areas include AC mains, renewable-energy and telecommunications.
