CAPACITOR / BATTERY LOAD-LEVELING OF HYBRID-VEHICLES WITHOUT THE USE OF ACTIVE INTERFACE ELECTRONICS: SLOW RESPONSE ENGINES

摘要

Simulations were conducted for the performance of passive combinations of capacitors with batteries using the "slow response PNGV power profile". This power profile requires a minimum of 3 kWHr of energy in the 400 to 300 V range. The capacitor was modeled as a series-RC circuit having a 1.5 s time constant. The battery model was derived using test data from a lithium ion battery manufactured by Saft. A major assumption about the battery was that it could reliably operate at and offer acceptable cycle life when subjected to repetitive 2.5-C charges and discharges.Results show that the optimum system for the slow response power profile, that is the one physically smallest or least expensive, has a 2475 WHr battery with a 54 F capacitor. This size capacitor stores 525 WHr of energy in the 400 to 300 V window. Thus, the total energy stored in the system for discharge and regenerative braking is 3000 WHr, the minimum specified requirement. Without a capacitor, the system would be larger and cost more. A similar conclusion was reached previously for the "fast response PNGV power profile."