CVT, promising solutions for Electrification
Benefits of the pushbelt variator in terms of costs, comfort and efficiency 2019-01-0359
The single gear transmission of electric vehicles (EV) puts hard requirements on the electric motor and battery to enable the full characteristics as offered by the internal combustion engine such as driving large distances at higher speed or towing a trailer. EV developers are facing several challenges in extending driving range, reducing recharge times and finding a performance and efficiency compromise between low speed and high-speed conditions.
This research proposes a combination of a dedicated CVT and e-motor that offers opportunities to overcome these challenges. The result is a cost effective and efficient solution where the surplus cost for the CVT is recovered within the powertrain by lowering the cost of the electric components, cooling system and battery.
A CVT reduces the maximum torque and speed requirement of the electric motor, which enables a reduced size and cost of the active parts. The combination of a downsized e-motor and a pushbelt CVT can deliver the good performance that EV-consumers expect from their vehicles.
This paper combines the results of research into various topics to confirm these statements.
A simulation based comparative study of various EV powertrain configurations shows that with respect to the single gear EV, efficiency benefits of up to 13% on WLTC are possible. A cost-study based on the bill of materials (BOM) furthermore concludes that a 6% cost benefit can be gained.
Francis Van der Sluis, Luc Romers, Gert-Jan Van Spijk, Ingmar Hupkes