Improvement of Total Regenerated Energy by Two Motors Considering Initial Speed-Ratio of CVT in Power-Train during Reducing Speed of Automotive

Abstract:

The purpose of this study is to propose a method to improve the total energy regenerated by two motors connected with Continuously Variable Transmission (CVT) in the power-train during reducing speed of automobiles, such as Electrical Vehicles (EVs) and Hybrid Electrical Vehicles (HEVs). In this study, to change the regenerating condition, initial speed-ratio of the CVT was changed to change the rotation speed of the SM during reducing speed of vehicle, since regenerated energy is affected by the rotational speed of motor. In experiments and simulations, the total regenerated energy was investigated when the speed of the vehicle was reduced from 40 to 0 km/h with -1.23m/s2 of negative acceleration, while the initial speed-ratio of the CVT was changed from 0.6 to 1.4. To investigate the effect of changing the initial speed-ratio of CVT on total regenerated energy, at first, the regenerated energy was measured by a test system driven by a single motor and a CVT. The total regenerated energy by two motors was also calculated by the simulation considering properties of constitutions in the power-train. Maximum improvement of total regenerated energy by one motor was obtained when initial speed-ratio of the CVT was approximately 0.9. It was confirmed that appropriate condition of the initial speed-ratio of the CVT was existed to improve regenerated energy. Total energy which was regenerated by two motors was improved approximately 122% in maximum by determining appropriate shift condition of the CVT, compared with that of conventional power-train driven by one motor. Even when the data of regenerated energy by two motors was compared with that through gears (ig=1.0), 35.4% of improvement was obtained at the condition where the maximum improvement was obtained by two. To improve totally regenerated energy, it was more effective to set the initial speed-ratio of the CVT on the pass of speed-ratio of the CVT when the electric power was generated by two motors, compared with that by single motor.

• Periodical: Applied Mechanics and Materials (Volumes 291-294)
• Pages: 886-891
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.291-294.886
• Online since: February 2013
• Authors: Masahiro Itani, Kazuya Okubo, Toru Fujii
• Keywords: CVT, HEV, Initial Speed-Ratio, Regenerative Brake

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