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Development Trends of E-axles: Technical Requirements, Advantages of Adding CVT

FOURIN has spoken with a powertrain development consultant, who is familiar with gears, especially CVTs, and world market trends, regarding technical requirements for the evolution of e-axle (an electromechanical integrated unit consisting of a motor, gear and inverter) to the next stage. The interview covered the following topics: Industry map of powertrain development, the latest trends of E-axle development, technical requirements of gears for next-generation E-axle development, especially the pros and cons of CVT use. In September 2019, VW announced the world's first mass-market BEV model the ID.3. VW has outsourced the model’s key component the-E axle on a global scale. E-axle proposals were solicited from suppliers. Supplier companies pooled management resources or collaborated with other companies to develop and commercialize E-axles. As a result, VW has adopted outsourced and in-house (inverters are outsourced) manufactured axles for its joint ventures in the Chinese market and for the European market. In addition to VW’s ID family, OEMs will gradually introduce mass-market BEVs to the market. The BEV market will expand especially in China where BEVs are favored by NEV regulations. Automobile technology development capabilities of European engineering service companies increasing influence is linked to Chinese capital, giving rise to a number of emerging BEV manufacturers. In addition, BEV product portfolio will expand similarly to conventional cars to meet diversifying user needs. In order to develop next-generation E-axles several technical issues must be addressed such as downsizing, high-speed rotation, small diameter and high voltage. E-axles are equipped with either parallel shaft gear or coaxial planetary gear. They both have their strengths and weaknesses. It is under consideration to add CVTs to E-axles to improve efficiency for a wide range of uses, including downsizing of motors and high-speed driving and to reduce power consumption in LCA (life cycle assessment). Although it increases cost, it can improve electricity consumption by about 6%. For this reason, it is a useful concept that can contribute to the reduction of CO2 on a global scale.
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