A combined optimal sizing and energy management approach for hybrid in-wheel motors of EVs

In-wheel motors (IWMs) substantially influence the output performance of electric vehicles (EVs). Size design and control issues are two critical factors to be explored. This paper proposes the use of hybridization for integrating dual motors to enhance EV system dynamics. A combined optimal sizing/control approach was developed using the global search method (GSM). The optimal control (torque ratio) of dual motors was first proposed using the nested-structure for-loop program to minimize the consumed power according to various power ratios. The next combined sizing/control developed using the GSM facilitated the search for the optimal control, power ratios, and T-N (Torque-Speed) ratios to minimize the accumulated energy consumed during ECE40 and UDDS driving cycles. The results from simulations of these two cycles indicated that the energy consumption during optimal control improved by 1.23% and 1.40%, 8.34% and 7.16% after optimal sizing, and the combined optimization improved total consumed energy by 15.31% and 15.16%, respectively. These results suggest that employing the novel hybrid IWM powertrains while using the combined sizing/control method can facilitate energy conservation. A real testing platform will be developed in the future. (C) 2014 Elsevier Ltd. All rights reserved.