An assessment of accessory loads in a hybrid electric vehicle

Hybrid electric vehicles have emerged as one possible solution to the problem of reducing harmful emissions, reducing the use of petroleum, and a reliance on foreign oil. Conventional gasoline vehicles typically rely on belt driven alternators to supply power for vehicle accessory loads. Hybrid electric vehicles that have operating modes with the engine not running require a power source that can supply these accessories even when the engine is off. Typically this power source is the high voltage Energy Storage System (ESS), which is used to supply power for the accessories through a DC-DC converter. Taking energy from this ESS increases the energy consumption of the vehicle and is thus a focus for improving total vehicle efficiency.