A 250W/30A fast charger for ultracapacitors with direct mains connection

This paper presents a fast and compact charger architecture for ultracapacitors with direct connection to 230V AC mains supply. The charger delivers a DC output current which allows compensation for inductive and other non-ideal behaviour in the EDLC at medium and high frequencies. The internal converter uses self oscillating control circuits which provide a variable switching frequency over a broad range. This allows the circuit to adapt to the variation of the output voltage (0-16.2V) and fluctuations of the mains network, thereby minimizing losses over the whole operating envelope.