Researchers at the Hybrid Electric Vehicle Research Center at the University of California have designed and constructed hybrid electric vehicles for the last 15 years. CVT research has been pursued simultaneously. The hybrid electric power train has the potential to greatly improve CVT vehicle performance and fuel economy. A torque scheduling and engine power control system is proposed to achieve maximum fuel economy. The control strategy is based on operation along the ideal operating line (IOL) during positive power production and the best efficiency condition for low and negative power. Thus, the most efficient operation for the hybrid or Engine/Electric-motor-battery system with a CVT is actually an ideal operating band (IOB). The concept is presented and discussed with respect to a large high power battery pack hybrid system. Simulation results showing the difference in fuel economy for continuous operation along an IOL and operation within an IOB are discussed. The strategy developed is to operate the system with a minimum of energy flowing in and out of the electrical system and to collect as much energy from deceleration as possible while sustaining the charge in the batteries, When driving at low speeds or when depleting the batteries, It is shown that the best strategy is to operate all electrically and not use the gasoline engine if the power demand is low.
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