Range-extender In-the-loop Method for Fuel Consumption Prediction of Hybrid Electric Vehicles

In the development of a range-extended electric vehicle, it is necessary to determine the control strategy of the range extender (REX) and evaluate the influence of its performance and operating conditions. In this paper, we propose a range-extender in-the-loop (REIL) method that is used to predict the vehicle fuel consumption more accurately. To develop the REIL method and perform experimental verification, the vehicle plant model, electric-drive control strategy, and REX control strategy are integrated into a vehicle control unit (VCU) for REX control, bench data acquisition, and bench monitoring. The VCU controls the REX to meet the power requirements of the simulated vehicle operations under a given driving cycle. The fuel consumed by the engine and power generated by the integrated starter-and-generator are measured during the tests, which are used in the vehicle fuel consumption calculation. We first describe the methodology and implementation of the REIL, and subsequently discuss the predicted results of a range-extended electric vehicle equipped with a 30 kW REX under the WLTC driving cycle. Comparing the predicted results of the REIL and software simulation methods, it is demonstrated that the REIL method improves the prediction accuracy of vehicle fuel consumption.