Transmission For Electric Vehicles Research Articles

Solar Based Wireless Power Transmission for Electric vehicle Charging Station

Wireless power transfer (WPT) using magnetic resonance is the technology which could set human free from the annoying wires. In fact, the WPT adopts the same basic theory which has already been developed for at least 30 years with the term inductive power transfer. WPT technology is developing rapidly in recent years. At kilowatts power level, the transfer distance increases from several millimetres to several hundred millimetres with a grid to load efficiency above 90%. The advances make the WPT very attractive to the electric vehicle (EV) charging applications in both stationary and dynamic charging scenarios. For energy, environment, and many other reasons, the electrification for transportation has been carrying out for many years. In railway systems, the electric locomotives have already been well developed for many years. A train runs on a fixed track. It is easy to get electric power from a conductor rail using pantograph sliders. However, for electric vehicles (EVs), the high flexibility makes it not easy to get power in a similar way. Instead, a high power and large capacity battery pack is usually equipped as an energy storage unit to make an EV to operate for a satisfactory distance. The problem for an electric vehicle is nothing else but the electricity storage technology, which requires a battery which is the bottleneck today due to its unsatisfactory energy density, limited lifetime and high cost. Keywords: Wireless Power transfer, Electric Vehicle, Battery

Dual-Transformer-Based DAB Converter With Asymmetrical Power Transmission and High-Power Density for Electric Vehicles

Dual-Transformer-Based DAB Converter With Asymmetrical Power Transmission and High-Power Density for Electric Vehicles

The Effects of the Lubricant Properties and Surface Finish Characteristics on the Tribology of High-Speed Gears for EV Transmissions

Electric vehicle (EV) transmissions operate at high speeds. High-speed operation puts higher demands on bearings, seals, and gears. Bearings in EV transmissions are prone to electrically induced bearing damage and may exhibit signs of pitting and fluting. Surface-initiated rolling contact fatigue is another common problem gaining increased attention lately. Most EV transmissions require a coupling between an oil-lubricated gearbox to an electrical motor that runs with minimal lubrication at very high rpm. The high mechanical and thermal stresses the seals are exposed to under starved lubrication conditions have a detrimental impact on their service life. Hence, proper lubrication is critical. In general, EV transmission fluids call for a somewhat different spectrum of properties compared to conventional ATFs. Gear tribology simulations open new ways to the design and optimization of lubrication for EV transmissions. Additionally, such simulations can also provide valuable insights into the effects of different oil properties on cooling and lubrication efficiencies, thereby helping in matching the lubricant and hardware characteristics for optimal performance. In the present communication, we demonstrate the effects of different lubricants and surface finishing technologies on the tribology of high-speed gears using tribological tests and advanced thermal elastohydrodynamic (TEHD) simulations. The important roles of lubricity additives and surface finish optimization are highlighted in conjunction with a move towards ultralow viscosity EV transmission fluids.

Optimal Gear Shift Control of Two-Speed Dual-Clutch Transmission in Electric Vehicle for Smoothness and Friction Loss Reduction

Optimal Gear Shift Control of Two-Speed Dual-Clutch Transmission in Electric Vehicle for Smoothness and Friction Loss Reduction

Drive-Cycle-Based Configuration Design and Energy Efficiency Analysis of Dual-Motor 4WD System With Two-Speed Transmission for Electric Vehicles

The development of energy-saving technology is important to the promotion of electric vehicles. In the design process of electric vehicles, the drive configuration is generally determined first, and then the energy management strategy is studied. However, this process doesn’t design the drive configuration with higher energy saving potential from the economic perspective of vehicle driving conditions, but directly determines the drive configuration. So, in this paper, the characteristics of the vehicle’s driving conditions are analyzed firstly, and then based on the analysis results, a new dual-motor 4WD EV configuration with higher energy saving potential is proposed, which only has a two-speed transmission in the rear axle. Then the parameters of the proposed driving configuration are calculated to meet the vehicle dynamic or economic needs of various driving conditions. Then an energy management strategy is developed for the judgement of optimal torque distribution of the front and rear axle motors and gear shifting logic. Finally, the comparison simulations are conducted and the results show that, in WLTC, DM-2ST can reduce vehicle energy consumption by 9.13% and 4.84% respectively compared to DM-FTD and DM-OTD. In UDDS, DM-2ST can reduce vehicle energy consumption by 11.04% and 5.77% respectively compared to DM-FTD and DM-OTD.

Development of Shift Map for Electric Commercial Vehicle and Comparison Verification of Pneumatic 4-Speed AMT and 4-Speed Transmission with Synchronizer in Simulation

As the automotive industry transitions from internal combustion engine vehicles to the era of electric cars, extensive research is being conducted in the field of electric vehicles. While a significant portion of this research focuses on the electrification of passenger cars, commercial vehicles have experienced relatively modest changes towards electric propulsion. Particularly, challenges related to power and efficiency have prompted a concentrated effort in addressing these issues. However, improvements in the efficiency of motors and inverters are reaching their limits, necessitating the development of multi-speed transmissions for electric commercial vehicles to enhance overall system efficiency. In this paper, the development of a 4-speed transmission with a synchronizer designed for electric commercial vehicles is presented as part of a project. A transmission shift map was developed, and verification of increased power and efficiency was conducted through a comparison with the existing product (a pneumatic 4-speed internal combustion engine transmission) installed in the target commercial vehicle. The study utilized vehicle dynamics, component modeling, and simulation environments to assess the improvements in performance.

Tribological behavior of electric vehicle transmission oils using Al2O3 nanoadditives

Antifriction and antiwear performances of Al2O3 nanoparticles (NPs) as additives of an automatic transmission fluid, ATF, are presented in this research. For this purpose, four nanodispersions were formulated: ATF + 0.05 wt% Al2O3 NPs, ATF + 0.10 wt% Al2O3 NPs, ATF + 0.15 wt% Al2O3 NPs and ATF + 0.20 wt% Al2O3 NPs to identify the optimal concentration of additive. Tribological experiments were taken at pure sliding conditions, with the formulated nanolubricants and the ATF, under a working load of 20 N. The four nanolubricants tested resulted in lower friction coefficients than those obtained using ATF, reaching a maximum reduction of 6 % with the ATF + 0.10 wt% Al2O3 nanolubricant. The tribological pairs tested with the Al2O3 nanolubricants show lower wear than those tested with the ATF, having the best wear decrease with the ATF + 0.10 wt% Al2O3 nanolubricant, with reductions of 45, 57 and 78 %, respectively, in diameter, depth and area of the wear scar. Furthermore, by means of confocal Raman microscopy, roughness evaluation and SEM-EDX of the worn tribological specimens, it can be determined that mending, tribo-sintering as well as rolling mechanisms occur.

Gear error control and response of electric vehicle transmission gearing based on gear trimming

The lightweight development of electric vehicle motors is a prominent future trend, with the challenge of transmission vibration and noise acting as a key bottleneck that limits the enhancement of power and speed in electric vehicle drive systems. The noise generated by electric vehicle transmissions is primarily associated with the transmission system and gear structure. In line with this, the present study proposes an analysis of transmission error and response mechanisms through gear modifications. The research delves into the analysis of gear deformation and error generation characteristics. It further investigates methods for parametric equation modeling, tooth profile modification, deformation imprint analysis, and vibration response modeling to examine excitation response analysis and noise reduction techniques pertaining to transmission errors. The findings demonstrate that, under 40 % torque, the shaped gear exhibited a maximum reduction in transmission error of 34.2 %, resulting in an overall error improvement of over 5.7 %. Moreover, the maximum error difference after tooth profile and tooth direction shaping exceeded 2 %. The gear-shaping-based electric vehicle transmission showcased favorable economic and technical performance, while its excitation response mechanism provided valuable guidance for mass production. Overall, these results highlight the significance of analyzing transmission errors through gear modifications in achieving lightweight electric vehicle motors. By addressing transmission vibration and noise issues, this research contributes to overcoming limitations and promoting advancements in power and speed within electric vehicle drive systems.

Two-Speed Transmission Structure and Optimization Design for Electric Vehicles

The trend in the global automotive industry is moving towards electric vehicles that do not emit exhaust gases and use eco-friendly fuel. Electric vehicles are more eco-friendly compared to internal combustion engine vehicles, as they emit less carbon dioxide and pollutants. Research and development are actively underway to produce new electric vehicle models in the rapidly growing electric car market. In this study, a 2-speed transmission for electric vehicles, applicable to 300 Nm-class electric cars, has been developed. The 2-speed transmission structure enables efficient energy use and utilizes a planetary gear set and wet multi-plate clutch, which are effective in the power transmission process. The 2-speed transmission developed through the research results of this paper has a compact structure optimized for electric vehicles. The design feasibility of the transmission was verified through performance tests of the prototype, contributing to fuel efficiency improvement and environmental enhancement.

Diamond like-carbon coatings for electric vehicle transmission efficiency

A barrier to the adoption of battery electric vehicles is consumer range anxiety. This paper investigates the driving range conceded as a result of the parasitic frictional losses incurred at the gear mesh in a two-stage battery electric vehicle transmission. Amelioration of the parasitic losses through changes to surface roughness and application of thin wear resistant coatings such as DLC are considered. The tribo-dynamics model of the gear frictional losses includes topographical structure of the respective surfaces characterised through surface specific fractal parameters. Analysis shows that the use of the investigated amorphous hydrogenated undoped DLC coating could potentially save 1.1 km of vehicle range during extra urban driving and 0.9 km under urban driving over a full battery discharge cycle.

Parameter Optimization and Control Strategy of Hybrid Electric Vehicle Transmission System based on Improved GA Algorithm

Most of the traditional hybrid electric vehicles (HEVs) choose to optimize the transmission ratio parameters, and the parameter changes of the whole vehicle and other components are only calculated as fixed values. It is difficult to give consideration to the optimization of the economy and power of hybrid vehicles. Therefore, the research proposes to build the transmission ratio, the required power of the vehicle’s working mode, and other models through the dynamic analysis. The parameters of the whole vehicle are optimized on the basis of parameter matching. At the same time, this paper chooses to adopt a hybrid optimization algorithm, combining particle swarm optimization (PSO) and genetic algorithm (GA). The weighted average method and constraint method are used to design the fitness function. The simulation experiment is carried out by Cruise software and MATLAB. Compare the iterative fitness of the PSO-GA algorithm with the traditional PSO and GA algorithm. It can be concluded that PSO-GA converges at the 12th iteration, with an average optimal fitness of 0.5239, which is higher than the traditional algorithm. At the same time, the parameter optimization of PSO-GA and the simulated annealing algorithm is compared. It is found that in the same task, the gasoline consumption after SA algorithm optimization is 0.561 L, while the fuel consumption under PSO-GA algorithm optimization is 0.475 L. The method proposed in this study has improved the power and economy of the HEV model and is effective.

Optimization of multi-speed transmission for electric vehicles based on electrical and mechanical efficiency analysis

Multi-speed transmissions for electric vehicles (EVs) can better improve EV efficiency and performance in comparison with conventional single-speed transmissions. To achieve a superior multi-speed transmission design, gear ratios and shifting patterns should be optimized by considering the electrical and mechanical efficiencies. Because most powertrain losses occur in the inverter, motor, and transmission, loss analysis was conducted according to the characteristics of each component. To confirm the effects of these component efficiencies on EVs, an EV efficiency analysis was performed based on three cases of powertrain efficiency by considering the variable efficiency of each component combination: i) motor only, ii) motor and transmission, and iii) inverter, motor, and transmission. An optimization problem was formulated by adopting design variables, such as gear ratios and shifting patterns, and the objectives of energy consumption and acceleration ability. An artificial neural network (ANN)-based multi-objective optimization process was proposed as an alternative to the excessive effort for calculation in the optimization process. To verify the importance of considering the efficiency of various powertrain components, transmission optimization was performed for the variable efficiency of each component combination. When comparing the highest efficiency solutions of the cases considering only part of component efficiency with the case considering all components, the energy consumption and acceleration ability of the latter case were found to be superior by approximately 1.7% and 5.1%, respectively. Furthermore, since the computational time for the EV and ANN models required approximately nine months and one day, respectively, this result demonstrates the effectiveness of the ANN-based multi-objective optimization process.

Analysis of Optimal Shift Pattern Based on Continuously Variable Transmission of Electric Vehicle for Improving Driving Distance

Extending the maximum driving distance of an electric vehicle would be beneficial given these vehicles’ long charging time and limited battery capacity and to improve electricity consumption. Research on the optimal development of the powertrain is essential because the efficiency of an electric motor varies according to the operating point. In this study, we developed a simulation analysis model with a continuously variable transmission. based on the commercial electric vehicle (Company B) model and using actual vehicle driving data supplied by the Argonne National Laboratory. The shift pattern of the continuously variable transmission was then optimized by considering the change in the operating point, constant motor output area, and transmission response speed. In addition, a performance comparison was made using the model with a single reducer. The results obtained by this study showed that electronic economy improved by approximately 5% when the continuously variable transmission was applied through the combined driving simulation. Furthermore, the time taken to accelerate 0–100 km/h and 80–120 km/h reduced by 15% and 6%, respectively. The maximum driving distance on a single charge improved by 7 km. It was confirmed that the driving performance of an EV with continuously variable transmission could be improved by downsizing the electric motor to reduce manufacturing costs.

Multi-Objective Optimization Of Gear Ratios In Two-Speed Dual Clutch Transmissions For Electric Vehicles

The rational matching and optimized design of the gear ratios for the transmission system of an electric vehicle (EV) are of great importance for improving economic and dynamic performances. This paper sets a pure electric vehicle (PEV) as the research object. First, the four common driving cycles considering the urban and suburban areas are selected and analysed which are applied for designing the gear ratios. Second, the parameter matching of the basic indicators of the EV performance and the selection of gear ratios are explored according to the analysis of the four selected driving cycles. Furthermore, gear ratios are set as the variables and the ant colony optimization (ACO) algorithm is applied to optimize the gear ratios by setting the sum of the power demand of the selected common driving cycles, the sum of the average motor efficiency of the chosen driving cycles, and the acceleration time as the objective function in order to optimize the vehicle performances. A two speed dual clutch EV model is constructed in MATLAB/Simulink for verification of the results. The simulation results demonstrate the effectiveness of the optimisation in comparison with the previous gear ratios, where both economic and dynamic performance improvements are evident.

Maximizing wireless power transmission for electric vehicles with high-intensity laser power beaming and optical orthogonal frequency division multiplexing

This paper presents a method for determining the optimal power transmission path for wirelessly charging electric vehicles using high-intensity laser power beaming in environments with multiple power transmitters and receivers. The proposed method uses an optical orthogonal frequency division multiplexing system. The power receiver selects the optimal power transmitter and wireless power channel based on the maximum power requirement. The paper also validates the proposed method through simulation and experimentation.

Study on the Design and Speed Ratio Control Strategy of Continuously Variable Transmission for Electric Vehicle

Study on the Design and Speed Ratio Control Strategy of Continuously Variable Transmission for Electric Vehicle

Development of vehicle driving cycles based on the real traffic dataset

The paper describes methods for generating (modeling) representative driving cycles of the vehicle used to solve engineering problems in the design of electric vehicles, such as resource calculations, determination of the required capacity of traction batteries and evaluation of power reserve, etc. The general approaches used in the processing of real traffic data and algorithms for modeling driving cycles using deterministic and probabilistic approaches are described. This paper presents driving cycles that ensure convergence with parameters corresponding to the real conditions of vehicle movement. The developed driving cycles can be used in the design of electric vehicle transmission components and allow for the analysis of operational properties.

Transmission Design and Control Optimization of an Electric Vehicle Using Analytical Modeling Methods

This paper introduces a framework to systematically optimize the design and control of an electric vehicle transmission, connecting powertrain sizing approaches with low-level gearbox design methods. To this end, we first create analytical models of the individual transmission components: gears, shafts, bearings, clutches, and synchronizers. Second, we construct a transmission by systematically configuring a topology with these components. Third, we integrate the composed transmission within a powertrain and vehicle model, and compute the minimum-energy control strategies and design, employing two solution algorithms, namely dynamic programming and exhaustive search, respectively, providing global optimality guarantees. Finally, we carry out the design and control optimization of a one- and two-speed transmission for a small electric family car, whereby we observe that a two-speed transmission can improve the energy consumption by 0.5% with respect to a one-speed transmission, whilst also satisfying the gradeability and performance requirements.

Method using torque mode of motor for the shift of two-speed planetary CLAMT in bilateral electric drive tracked vehicle

For the shift control of clutchless automotive manual transmission (CLAMT) in electric vehicle, great difficulty is caused by the high level of precision and rapidity requirements of the speed and mode response of motor as well as the position response of gearshift sleeve, especially when confronted with off-road environment. To overcome the difficulty and achieve fast shift, a practical control method is proposed and applied to two-speed planetary CLAMT for off-road tracked vehicle with bilateral electric drive system, wire control system and unmanned driving purpose. In shift process, the method lets motor be controlled by applying torque mode and constant torque during active speed adjusting phase, lets gear engaging phase be started at the time when transmission ratio is regulated beyond a certain value close to target gear ratio – that is, at the time when the approach of synchronized state is achieved, lets synchronizer make a help for precise gear synchronization. Theoretical analysis of gear synchronization process is carried out. By increasing the level of motor torque, the duration of active speed adjusting phase can be obviously shortened. With the approach of synchronized state judged by using transmission ratio margin of small fixed positive value for reference, gear engaging phase can be achieved quickly. Off-road experiments show good performance of the shift control method. Experimental results and phenomena are discussed in detail for further and better understanding of real shift process.

Dynamic Simulation and Experimental Study of Electric Vehicle Motor-Gear System Based on State Space Method

In the research on electric vehicle transmission vibration characteristics, the dynamic model involving a multistage gear system is still rare, especially the influences of driving motor excitation and load excitation which are not considered, and which makes the gear system research deviate from the actual situation. In addition, the changing processes of variables are usually simplified or neglected in the study of gear systems, which is not conducive in revealing the mechanism of gear dynamic behavior. In this paper, an improved dynamic model of a motor-gear system is established. The influences of driving motor excitation and load excitation are included, and the changing processes of tangential, axial, and torsional vibration variables of driving gear and driven gear are obtained using the state space method. Furthermore, the transmission housing vibration responses are investigated. By comparing the simulation results with the measurement data, the improved dynamic model, as well as the state space solution method, are verified as reliable and universal. On this basis, the influence of motor excitation on the state change of the gear system is discussed, which provides a theoretical approach for further study of motor drive gear systems.