Improvement of operating strategy for parallel hybrid cars by adaptation to actual route and electrical on-board load

An analytic operation strategy calculates the operation points for the combustion engine and the electric motor following a cost function to minimize the fuel consumption. To increase the lifetime of batteries the state of charge (SOC) range used should not be bigger than 10%. The limited usable SOC range and the low fuel consumption are conflicting goals. This paper shows that the cost function can be designed in a manner that a low fuel consumption and a well balanced SOC is possible. In addition, an adaptation of cost function parameters to the actual route can also increase SOC stability. Also the influence of the on-board load on the SOC can be controlled in a way that the SOC change can be kept within the allowed range. Thereby it is possible to minimize the effect of limited charge exchange on the functionality of the hybrid drive train and its capacity to save fuel.