Performance analysis of automotive power systems: effects of power electronic intensive loads and electrically-assisted propulsion systems

Demands for higher fuel economy, performance, and reliability as well as reduced emissions push the automotive industry to seek electrification of ancillaries and engine augmentations. In the future cars, throttle actuation, power steering, anti-lock braking, rear-wheel steering, air-conditioning, ride-height adjustment, active suspension, and electrically heated catalyst will all benefit from the electrical power system. Therefore, a higher system voltage, such as the proposed 42 V, is necessary to handle these new-introduced loads. On the other hand, due to the environmental concerns, there is a definite development towards new electrically-assisted propulsion systems that improve fuel economy. In this paper, the effects of the new introduced electrical systems including hotel and auxiliary loads on the electrical power systems of conventional and more electric cars are presented. Dynamic characteristics of electrical loads are defined for typical drive cycles. Finally, system level issues such as fuel economy and vehicle performances are addressed.