Hybrid Power Unit Development for Fiat Multipla Vehicle 981124

In the “scenario” of increasing concerns for environmental pollution, hybrid vehicles will play a significant role in the near future. Compared to electric vehicles, the hybrid ones have an unrestricted driving range, higher performance and transport capability, still fulfilling ZEV emission regulation.

The hybrid vehicle features a power train that integrates a thermal engine with an electric motor. Among the several possible configurations for hybrid vehicle, the parallel hybrid one has been chosen for the FIAT MULTIPLA, for the following reasons:

• lower weight and volume of the electric unit to obtain the same driving mission;
• higher global efficiency of the system, due to direct thermal to mechanical energy conversion;
• a better vehicle performance (acceleration and max speed), thanks to the contribution of both motors to traction.

In the development of a hybrid parallel concept, the critical aspects to be overcome are related to the system mechanical complexity and the simultaneous control of the two motors.

In this paper the Fiat Auto and Elasis approach to the hybrid vehicle is presented with particular reference to the powertrain unit and its control strategies.