Hybrid drives are vehicles with at least two different energy sources and two different types of drive units. Designation of the type of drive unit as well as its use is established by the operating strategy. An operating strategy becomes necessary as soon as there is at least one degree of freedom for the adjustment of the powertrain system. This refers to the adjustment of the combustion engine operating point, as well as to the adjustment of the gearing of the powertrain. The aim of an operating strategy is to run the vehicle as economically as possible in terms of fuel consumption. The basis for the operating strategy calculation is the minimization of efficiency loss for the entire vehicle by utilizing the degreee of freedom for the adjustment of the powertrain components. This covers the total efficiency loss for all of the indvidual vehicle components, including the combustion engine. By minimizing the losses, a clear correlation is obtained between driving condition and the nominal operating values of the combustion engine and of the gear ratios of the powertrain. At this point, the battery charge condition has not yet been taken into account. The vehicle should be able to be independent-operation driven, i.e., operated independently from the mains. For this reason, the battery charge condition should not drop below a specific threshold. If the battery charge condition deviates from the nominal value, the strategy of loss minimization needs to be modified so that the battery state of charge will be returned to its nominal value. Additional efficiency loss must be taken into account to maintain correlation between the battery charge condition and its nominal value. The additional loss is minimized by means of a sensitivity analysis. The net result is an operating strategy providing for all modes of operation. The procedure applied here is applicable for any type of hybrid vehicle. This strategy has been developed independently of specific driving tasks. The sole criterion is prevailing efficiency loss for the current operating point. Economic fuel consumption and independent operation are thereby guaranteed for a wide variety of driving tasks.
Integration of reliability and a method for calculating hybrid vehicle operating strategies
Integration der Zuverlässigkeit und ein Verfahren zur Errechnung von Betriebsstrategien für Hybridfahrzeuge
1999
12 Seiten, 14 Bilder, 1 Tabelle, 10 Quellen
Conference paper
English
Integration of Reliability and a Method for Calculating Hybrid Vehicle Operating Strategies
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