Torque control strategy for a parallel-hybrid vehicle using fuzzy logic

In this article, we introduce a fuzzy logic controller to the driving strategy of a hybrid electric vehicle (HEV). The decision making of this fuzzy logic controller is useful to nonlinear and uncertain systems such as electric vehicle applications, and the fuzzy logic controller is immune to various vehicle load and road conditions. To construct the proper rule base of the fuzzy logic controller, the torque-producing, pollutant-emission, and fuel-consumption characteristics of the diesel engine and the hybrid system are clarified through dynamo testing. Then, the driving patterns of the driver and vehicle load on the service course are investigated. These results are also reflected in constructing the rule bases of the proposed fuzzy logic controller. To prove the usefulness of the proposed fuzzy logic controller, actual road tests of the parallel HEV are carried out. Note that the battery maintains its nominal voltage through 20 days of running without extra charging process.