Eco-friendly vehicle design and control


electrified Manual Transmission (eMT)  


The eMT is a hybrid powertrain that can be implemented simply by inserting a electric motor into a conventional manual transmission. The electric motor can not only function as an additional power source, but also enables shifting without clutch operation by synchronizing the speed of the transmission input shaft and the speed of engine output shaft [1, 2].


The eMT is a very suitable structure for low-cost hybridization, and this is why we have been working on modifying the actual manual transmission truck (especially delivery service truck) into the eMT structure (Fig. 1). Delivery service trucks have been recognized as one of the main causes of urban air pollution and we think the eMT, low-cost hybridization technology, would be a feasible solution for air pollution problems.

 Fig. 1. Modification of a manual transmission to the eMT





Fig. 2. Mechanical and electrical configuration of the vehicle modified to the eMT




 Fig. 3. ‘친환경 택배 트럭’ 상용화…매연·미세먼지 20% (KBS1 – 7시 뉴스)




[1] Hybrid vehicle having interactive manual transmission and control method therefor

[2] Economic hybrid transmission system using clutchless geared manual transmission


A Novel Flywheel Hybrid Powertrain 


A novel flywheel hybrid powertrain is proposed. It is composed with multi-planetary gear system (PGS) and CVT. Combining the power split function of PGS and continuous gear ratio shifting function of CVT, the proposed configurations can control driving mode and power split ratio with only 2 control DoF. It is done by changing the relative location of free node by controlling CVT ratio.




Fig. 1. A novel flywheel powertrain



Clutchess Geared Smart Transmission (CGST) 


Among many powertrains, the parallel hybrid powertrain has gained popularity thanks to minimal design changes from the conventional transmission. However, it does not guarantee seamless torque transmission by use of clutches or torque coupler, and it has limited engine operation by coupling with final drive. Moreover, viscous friction and hydraulic units for clutch actuations induce energy loss. To solve theses limitations, novel clutchless parallel hybrid powertrain so called Clutchless geared smart transmission (CGST) is proposed.

The CGST can smoothly change power flow of input gear shafts by controlling the electric motor that is connected to the planetary gear set (PGS). Moreover the CGST can provide seamless torque transmission even while shifting gears due to absence of torque interruption.


          Fig. 1. 
Comparison between (a) switching parallel hybrid powertrain and (b) CGST


[1] Kim, Sun Je, Kyung-Soo Kim, and Dongsuk Kum. "Feasibility Assessment and Design Optimization of a Clutchless Multimode Parallel Hybrid Electric Powertrain." IEEE/ASME Transactions on Mechatronics 21.2 (2016): 774-786.

[2] Kim, S. J., et al. "Fuel economy assessment of novel multi-mode parallel hybrid electric vehicle." International Journal of Automotive Technology 16.3 (2015): 501-512. 

[3] Kim, S. J., et al. "Analysis of the shifting behavior of a novel clutchless geared smart transmission." International Journal of Automotive Technology 15.1 (2014): 125-134.

[4] Kim, Sun Je, et al. "Verification of the Shifting Mechanism of Clutchless Geared Smart Transmission using the Compact Car Size Test Bench." Vehicle Power and Propulsion Conference (VPPC), 2013 IEEE. IEEE, 2013.

[5] Yoon, Y-S., S. J. Kim, and K-S. Kim. "Conceptual design of economic hybrid vehicle system using clutchless geared smart transmission." International Journal of Automotive Technology 14.5 (2013): 779-784.

[6] Song, Chiwoong, et al. Dynamic analysis and experimental verification of a clutchless geared smart transmission system for hybrid cars. No. 2013-01-1454. SAE Technical Paper, 2013.

[7] San Yoon, Yong, Sun Je Kim, and Kyung Soo Kim. "Gearbox having multiple input axles and transmission device using the same." U.S. Patent Application No. 13/435,492.

[8] Yoon, Yong-San, Kyung Soo Kim, and Sun Je Kim. Clutchless geared smart transmission. No. 2011-01-2031. SAE Technical Paper, 2011.

Internal combustion engine modeling with transient state analysis and intelligent control


The characteristics of the internal combustion engine change in real time caused by transient state, temperature and abrasion, and fuel consumption increases. However, conventional power distribution control methods do not fully consider these characteristics. Therefore, it is necessary to model the engine that can reflect the transient state and establish a control strategy that can lead to improved fuel economy by predicting accurate fuel consumption. Existing characteristic maps of IC engines are obtained through experiments that runs heated engines in steady state at varying torque and speed. However, the conventional engine map is inaccurate because the engine characteristics are affected by temperature and vary greatly in transient state. If the engine temperature is low, the fuel consumption increases proportionally, and even during transient such as engine on/off, rapid torque increase, etc. Depending on driving conditions such as ramps, road conditions, and driver driving habits, the powertrain's fuel consumption will become sensitive, which requires a power distribution control strategy that controls the engine and motor more intelligently.




[1] Yan, Fengjun, Junmin Wang, and Kaisheng Huang. "Hybrid electric vehicle model predictive control torque-split strategy incorporating engine transient characteristics." IEEE transactions on vehicular technology 61.6 (2012): 2458-2467. 

[2] Lin, Xinyou, Binhao Zhou, and Yutian Xia. "Online Recursive Power Management Strategy based on the Reinforcement Learning Algorithm with Cosine Similarity and a Forgetting Factor." IEEE Transactions on Industrial Electronics (2020).

MSC Lab.4F(#3434~#3446) ID B/D(N25), School of Mechanical Aerospace & System
Engineering : Division of Mechanical Engineering, KAIST, 373-1, Guseong-dong, Yuseong-gu, Daejoen, Korea, 305-701.
Tel:+82-42-350-3268 l Fax:+82-42-350-5201