A topology-change model of multi-speed transmissions in electric vehicles during gear-shifting

Abstract

Recent developments in electric vehicles incorporate multi-speed transmissions to improve the electric vehicle range and performance. Similar to transmissions for fossil-fuel vehicles, those for their electric counterparts undergo topology changes during gear-shifting. However, this important phenomenon has been overlooked in the development of transmission mathematical models, which results in inaccurate prediction of the transmission dynamic response. In this study, a topology-change model based on the impulse-momentum relation is developed to address the topology change of multi-speed transmissions in electric vehicles during gear-shifting. An orthogonal complement is introduced to eliminate the non-working constraint forces. The velocity jump brought about by topology changes is given due attention. A case study is included, whereby the model is applied to a novel modular multi-speed transmission for electric vehicles. First, tests are conducted on the transmission experimental testbed; then, the test results are reproduced in simulation using the model developed herein. Moreover, the velocity jump of the gear-shifting is computed by means of the model. Subsequently, simulation of the transmission gear-shifting incorporating the velocity jump is conducted. It is shown that the topology-change model improves the accuracy of transmission mathematical models in predicting transmission dynamic responses during gear-shifting.

Redesign of a Disc-on-Disc Computer Numerical Control Tribometer for a Wide-Range and Shudder-Resistant Operation

“…As outlined in Section 2.1, the tribometer comprises two servo axes: rotating and linear ones (see Figure 1). The pressure plate (8) is carried by the vertical axis as a source of variable normal load. The connection is realized directly through a precise, stiff, and compact normal force and torque piezoelectric sensor (4), thus, preventing any parallel (typically friction loss) force/torque transfer paths that would affect the measurement accuracy.…”

“…The automation of dry clutches brings the combination of cost and energy efficiency advantages with the driving comfort of traditional automatic transmissions [3], while mitigating the thermal and friction uncertainty disadvantages through proper control actions [2]. Hence, dry clutches are considered for various transmission architectures including clutch-by-wire (i.e., E-clutch) systems [4], automated manual transmissions (AMT) [5,6], dual clutch transmissions (DCT) [5,6], continuously variable transmission (CVT) systems [7], as well as different hybrid electric [5,6] and fully electric [8] vehicles. The development of clutch/transmission control and monitoring strategies requires accurate clutch models, particularly those related to two friction lining material features: coefficient of friction (COF) [9,10] and wear [11].…”

Precise and coordinated gearshift control for AMT gearshift system equipped with two linear actuators

“…This makes it easier to produce quick and smooth gearshift performance because of the drive motor's quick adjustment capability, which includes torque and speed. Because of this, numerous research use AMT to increase the EVs' drive range [6][7][8][9]. Meanwhile, it is also possible to enhance the EVs' dynamic performance.…”

Analysis of the Accuracy of Mass Difference-Based Measurement of Dry Clutch Friction Material Wear

“…Dry clutches have recently been considered for implementation in different hybrid [1,2] and fully electric [3] vehicles, in addition to being used in manual transmissions, automated transmissions, such as AMTs and DCTs [4,5], and E-clutch-based transmissions [6]. Accurate clutch models are required for simulation, monitoring, and control purposes of the above-mentioned transmissions.…”