Development of continuously variable transmission and multi-speed dual-clutch transmission for pure electric vehicle

Abstract

Pure electric vehicles, as a promising alternative to conventional fossil fuel-powered passenger vehicles, provide outstanding overall energy-utilizing efficiency by omitting the internal combustion engine. However, because of lower energy density in battery energy storage, the driving range per charge is limited by this electrochemical power source, leading to a socalled range phobia and presenting a major barrier for large-scale commercialization. The widely adopted single-reduction gear in pure electric vehicles typically do not achieve the diverse range of functional needs that are present in multi-speed conventional vehicles, most notably acceleration performance and top speed requirements. Consequently, special-designed multi-speed pure electric vehicle-powertrains have been compared and investigated for these applications in this article. Through the optimizing of multiple gear ratios and creating special shifting strategies, a more diverse range of functional needs is realized without increasing the practical size of the electric motor and battery. This article investigates the performance improvements of pure electric vehicle realized through utilization of multi-speed dual-clutch transmissions and continuously variable transmissions. Results reveal that there can be significant benefits attained for pure electric vehicles through multi-speed transmissions. Simulation results shows that continuously variable transmission and two-speed transmission are the two most promising transmissions for pure electric vehicle in different classes, respectively.

Gear Ratio Optimization along with a Novel Gearshift Scheduling Strategy for a Two-Speed Transmission System in Electric Vehicle

“…Gear Ratios Shift Scheduling Parameters Limitations of Shift Scheduling Strategy 4-Speed [10] 14.4/10.4/7.2/5.2 Throttle Position Vehicle speed Suitable for flat road and may not be suitable for all driving cycles simultaneously. It is ensured that a certain velocity will be achieved at maximum road gradient.…”

“…According to this method, the gearshift schedule line is drawn by connecting the intersection points between the electric motor efficiency lines for two consecutive gears at several sets of throttle position and vehicle speed. Although the developed gearshift schedule has been applied in other studies conducted by Ruan et al [10] and Ruan et al [11], this technique is inherently complex. Moreover, although the motor efficiency and different vehicle driving conditions are considered, in practice, the traditional rule-based (i.e., throttle position and vehicle speed) gearshift schedule is a fixed gearshift schedule and may be effective for certain driving scenarios.…”

A Novel Dual-Motor Two-Speed Direct Drive Battery Electric Vehicle Drivetrain

“…various multi-speed transmissions implementations in BEV, like Automatic Transmission (AT), Automated Manual Transmission (AMT) and Continuously Variable Transmission (CVT), can be found in [8]- [10]. Results from above studies clearly demonstrated that multi-speed transmission not only improve the dynamic and economic performance of BEVs, also ease the high upfront cost by a cheaper daily cost and maintenance fee from the viewpoint of long-term ownership.…”

“…Furthermore, splitting one propelling motor to two increase the possibility of higher motor operational efficiency via optimized design of motor torque-speed characteristic and engaged gear ratios. The reason of adopting a twospeed powertrain, rather than others, is that it can achieve the best balance of motor efficiency improvement and additional cost [10]. Through the proposed powertrain and related control strategy, the scientific contribution of this paper will fill the knowledge gap of existing research in following aspects:…”

Condition-based maintenance strategy for vehicles using hidden Markov models

“…5 The speed control of an electromagnetic direct drive vehicle robot driver has been done with neural network to obtain driving vehicle with manual transmission and automatic transmission in various test conditions. 6 The performance improvements of pure electric vehicle have been presented by utilization of multi-speed dual-clutch transmissions and continuously variable transmissions. 7 Optimization of lane-change time to avoid collisions with other vehicles has been proposed, 8 for shortest time free lane change and emergency obstacle avoidance lane change.…”