The Use of Hybrid-Power Sources for Improved Performance with Pulsed Loads

摘要

Electrical characteristics of hybrid power sources consisting of Li-ion cells and double layer capacitors were studied at 25°C and -20°C. The cells were initially evaluated for pulse performance and then measured in hybrid modes of operation. Cells manufactured by Panasonic delivered pulses up to 3 A and cells from A&T delivered 4A at 25°C before cell capacity dropped. Measured cell resistances were 0.15 ohms and 0.12 ohms, respectively. These measurements were repeated at -20°C. Direct coupling of the cells and capacitors ("dumb hybrid") extended the pulse limits to 5.6A using the Panasonic cells and 9A for the A&T cells. Operation in a "smart hybrid" mode using uncoupled cell/capacitor discharge allowed full cell capacity usage at 25°C and showed a factor of 5 improvement in delivered capacity at -20°C.