Abstract
Research and/or Engineering Questions/Objective
The distance per battery charge of electric vehicles depends on the performance of a regenerative braking in the vehicle. In this paper, the drive performance and behavior of two-wheeled electric vehicle were analyzed according to the performance of the regenerative braking and then were analyzed through experiments using chassis dynamo.
Methodology
The experiment was held in Daegu Mechatronics & Materials Institute, using the chassis dynamo for electric two or three-wheeled vehicles and small-size electric vehicles. The two-wheeled electric vehicle (Ionic4, SAEKYUNGEV) was set in the chassis dynamo, and then the performance tests were carried out in test drive modes (Mopeds mode, CVS40 mode and WMTC mode). The driving load on the controller followed the guidelines of KS R ISO11486:2009 (Motorcycles —Methods for setting running resistance on a chassis dynamo). The level of regenerative brake was set to a certain percentage of the maximum forward driving torque. The default level of regenerative braking was set to 15%, and then the values were changed. Using measurement equipment, battery output, wheel torque on the chassis dynamo roller, angular velocity, and absorbed power were measured. Then based on the recorded test data, drive distance, battery power consumption per 1km, driving efficiency on different levels of regenerative braking were calculated for every test drive mode.
Results
It was confirmed that the driving distance and the battery power consumption change as level of regenerative braking changed. Each drive mode also showed different outcomes under different levels of regenerative braking. But, the observations for dramatic changes due to regenerative braking levels were absent without concerns about the (-) driving load under the condition that the vehicleis going downhill. For future studies, the difference in the control logic of regenerative braking between having the acceleration pedal off and having the brake on is necessary to study.
Limitations of this study
The gradient of the slope which is set to 0 or 2% for different test drive modes is considered as the limitations of this study. The energy savings due to regenerative braking come in use under high gradient and long downhill in real life driving experiences. The results of the study therefore do not show the driving behavior on actual road according to regenerative braking. Also, although it is acknowledged that the effects of regenerative braking are different when regenerative braking is started with the brake on and with the acceleration pedal off, the test model only performed regenerative braking when the brake was activated.
What does the paper offer that is new in the field including in comparison to other work by the authors?
Through testing the commercialized two-wheeled electric vehicle while changing the level of regenerative braking, as well as different driving modes, the driving performances were compared. From the analysis of the results of the experiment, it was found that the methodology of using chassis dynamo for analyzing the effects of regenerative braking has severe limitations.
Conclusions
Two-wheeled vehicles are designed to drive in urban environments, where being lightweight causes the vehicle to have small mechanical momentum, resulting in driving performance of regenerative braking that are difficult to analyse without consideration of downhill condition. In order to maximize the driving efficiency of two-wheeled vehicles by applying energy regenerative energy recovery mechanisms such as regenerative braking, new experimental methodologies and new test drive mode are required.
Key Words : Two-wheeled; Electric vehicle; Regenerative braking; Chassis dynamo;Driving performance