Eddy Current Couplings for Mild Hybrid Trucks

This paper looks at new possibilities to design mild hybrid power trains for truck applications using an eddy current assisted coupling between the main diesel engine and the electrical machine. This will allow the start-up of the engine by means of the eddy current coupling and only once the speed of the engine is synchronized, the conventional friction clutch will be engaged. Since no physical contact is established during the start-up period, the life of the system is prolonged due to a “wear-free” method of power transmission. Analysis of the coupling requirements is presented based on the specification of a 7.5 ton delivery vehicle for use in urban areas. Analytical and finite element models are used to predict the performance of the coupling. These results are then compared to measurements.