Electric Gear Research Articles

An Investigation of Dynamic Behavior of Electric Vehicle Gear Trains

Abstract The automotive industry has been experiencing a significant transition toward electrified powertrains in recent years. A torsional model of a common type of electric vehicle (EV) drivetrains is proposed to demonstrate certain dynamic behaviors that are unique to such high-speed applications. This two-stage helical gear drive train is supported by three shafts and connects the electric motor to the vehicle axle. The gear mesh interfaces are modeled by periodically time-varying stiffnesses subjected to backlash and displacement excitations to represent gear tooth errors and modifications. In addition to these internal excitations, torque fluctuations caused by electric motor are included as the external excitations. Two different operating conditions are studied here: (i) steady-state response as the vehicle is operated under steady torque conditions and (ii) transient response during EV system transitions between the drive and regenerative (regen) braking modes of operation. The torsional model predictions are verified through comparisons to simulations from a deformable-body contact model. Parameter sensitivity studies are performed to demonstrate nonlinear behavior of a helical gear train caused by external torque fluctuations as well as the interactions between external and internal excitations. Finally, drivetrain structural modes are shown to respond to drive-regen transitions resulting in certain transient (vibro-impact) behavior with elevated dynamic mesh forces.

Numerical investigation on tooth surface waviness in continuous generating grinding of electric vehicle gears considering the main shaft vibration and grinding worm wear

The objective of this paper is to present a numerical approach to investigate the formation mechanism of tooth surface waviness in CGG of electric vehicle gears while independently analyzing each influencing factor and ignoring the mutual influences between them. A tooth surface waviness simulation model is proposed considering the system vibration and tool wear. According to the characterization of grinding worm wear and the main shaft vibration in CGG, the grinding worm wheel and the grinding trajectories are modeled. Based on the analysis of the geometric contact characterizations through the whole grinding process, tooth surface topography is modeled, and tooth surface waviness is extracted. By comparing the tooth surface waviness in the frequency domain, the influence of grinding worm local wear, global wear, and the main shaft vibrations on tooth surface waviness is studied. Local wear and global wear affect tooth surface waviness differently by changing the amplitude and the distribution pattern of the frequencies. The main shaft vibrations have limited direct impacts on the amplitude in profile and flank spectrums, among which the vibration Z plays a leading role.

A high-speed gear reshaping method for electric vehicles combining the effects of input torque and speed variation.

In this study, we introduce an optimization method for high-speed gear trimming in electric vehicles, focusing on variations in input torque and speed. This approach is designed to aid in vibration suppression in electric vehicle gears. We initially use Tooth Contact Analysis (TCA) and Loaded Tooth Contact Analysis (LTCA) to investigate meshing point localization, considering changes in gear tooth surface and deformations due to load. Based on impact mechanics theory, we then derive a formula for the maximum impact force. A 12-degree-of-freedom bending-torsion-axis coupled dynamic model for the helical gear drive in the gearbox's input stage is developed using the centralized mass method, allowing for an extensive examination of high-speed gear vibration characteristics. Through a genetic algorithm, we optimize the tooth profile and tooth flank parabolic modification coefficients, resulting in optimal vibration-suppressing tooth surfaces. Experimental results under various input torques and speeds demonstrate that the overall vibration amplitude is stable and lower than that of conventional gear shaping methods. Specifically, the root mean square of vibration acceleration along the meshing line under different conditions is 58.02 m/s2 and 20.33 m/s2, respectively. The vibration acceleration in the direction of the meshing line is 20.33 m/s2 and 20.02 m/s2 under varying torques and speeds, with 20.33 m/s2 being the lowest. Furthermore, the average magnitude of the meshing impact force is significantly reduced to 5015.2. This high-speed gear reshaping method not only enhances gear dynamics and reliability by considering changes in input torque and speed but also effectively reduces vibration in electric vehicle gear systems. The study provides valuable insights and methodologies for the design and optimization of electric vehicle gears, focusing on comprehensive improvement in dynamic performance.

Exploring mass and economic potentials of rare earth elements recycling from electric vehicles at end-of-life

AbstractRare earth elements (REEs) are fundamental for various modern technologies and industrial applications. One significant application of REEs is in the production of neodymium-iron-boron (NdFeB) magnets, which are key components in electric vehicles (EVs), wind turbines, and electronic devices. These applications play a crucial role in driving the ecological and digital transition, highlighting the significance of REEs as strategic materials. With the dominance of very few countries in the REEs global supply and the rising of EVs demand, several concerns regarding resource availability, supply chain security, and price volatility have heightened the importance of efficient NdFeB magnet recycling, especially in Europe. This study assessed the elemental recycling potential of REEs from EV components through collaboration with authorized treatment facilities and metal recyclers in Italy. The study focused on three representative electric vehicles: a compact car, a van, and a hybrid vehicle. NdFeB magnets were found in various components, including the electric drive motor, air conditioning system, electric power steering, alternator, and electric gear box. The content of NdFeB magnets and REEs inside these components has been determined and economic feasibility of their recycling has been estimated by considering the intrinsic value of the raw materials contained. Despite being preliminary results, the economic value of REEs and Cu recoverable attested a promising potential for recycling, while the direct dismantling of magnets from the engine proves economically unviable for the studied components. Therefore, the study emphasizes the need for the development of specific recycling processes such as demagnetization and mechanical processing of the motors. The study also analysed the dismantling times of the target components from the vehicle and their relative economic impact on the potential for recovery.

Stages of Development and Current Trends in the Development and Production of Automobile Electric Gear Motors

Stages of Development and Current Trends in the Development and Production of Automobile Electric Gear Motors

Effect of grinding parameters on tooth surface waviness in continuous generating grinding for electric vehicle gears

Compared with traditional fuel vehicle gears, electric vehicle (EV) gears in its transmission system suffer harsher working conditions with stricter quality demands. Especially, regarding the need for low noise, as an indispensable acceptance indicator in the EV gear manufacturing industry, tooth surface waviness of EV gears has received great attention. However, in continuous generating grinding (CGG), many factors affect tooth surface waviness and tooth surface waviness is still highly unpredictable. Therefore, aiming at improving the gear noise of EVs, the effect of grinding parameters (grinding speed, feed rate, and normal stock) on tooth surface waviness is clarified with other interferences eliminated. Considering the characterization of both CGG and tooth surface geometry, a tooth surface evaluation approach for a single tooth surface was proposed to characterize the meso-scale surface geometric unevenness and directly reflect the processing quality. A tooth surface waviness model was proposed to study the effect of grinding parameters on tooth surface waviness. In the model, the spatiotemporal variability characteristics in CGG are considered while ignoring system vibration, machine tool errors, and so on. By simulating the evolution process of the remaining flank stock, tooth surface topography is modeled, from which simulated tooth surface waviness is extracted. To verify the proposed tooth surface waviness model, the gear grinding experiments were conducted. Under different grinding parameters, the simulated tooth surface waviness is consistent with the experimental results in the length-domain and frequency-domain. Furthermore, it was found that grinding parameters change the flank mean value, flank peak-to-peak value, and profile mean value in length-domain, and influence the distribution pattern and amplitude of the spectrums in the frequency-domain. Profile tooth surface waviness was found to be influenced by grinding parameters irregularly and flank tooth surface waviness was found to be more susceptible to the change of normal stock in the length-domain and frequency-domain.

A Hybrid Microgrid Operated by PV Wind and Diesel Generator with Advanced Control Strategy

All for a local area that gets its power from a solitary diesel generator (DG), this examination presents an efficient power energy choice for a microgrid. A twin feed enlistment generator draws power from a sun oriented photovoltaic (PV) cluster and the breeze to run this microgrid's electrical gear (DFIG). Two voltage source converters (VSCs) are sequentially coupled on the rotor side of the DFIG and share a DC transport that at last prompts the photovoltaic modules. Likewise associated with a similar DC transport as the DFIG stator is a bidirectional buck/help DC converter and a battery energy capacity (BES) to retain any overflow power. Most extreme energy collecting from the breeze and sun is accomplished by regulation of the bidirectional buck/help DC converter and the rotor side VSC. A changed form of the irritate and notice (P&O) technique is introduced for of expanding the energy result of a PV framework. Endeavors are being made to change VSC on the heap side to further develop DG's eco-friendliness. The ideal fuel-use reference DG power result may now be resolved utilizing a new, more broad methodology. Using the Sim Power Systems toolbox in MATLAB, we model and simulate many scenarios, including fluctuating wind speeds, fluctuating insolation, the impact of fluctuating load conditions on a bidirectional converter, and an unbalanced nonlinear load linked at the point of common coupling (PCC). Finding sinusoidal and balanced DG and DFIG stator currents.

Winding changeover as electric gear stage for main spindle drives

Winding changeover as electric gear stage for main spindle drives

A review on deep learning based condition monitoring and fault diagnosis of rotating machinery

Rotating machine faults are unavoidable; thus, early diagnosis is essential to avoid further damage to the machine or other machine attached to it. Various signal analysis based conventional techniques have been developed and used in the industries to identify various defects in the rotating machines. In last two decades, researchers have shifted their focus to automated or intelligent fault diagnosis based on Artificial Intelligence (AI) techniques due to a variety of issues in conventional fault analysis techniques, such as a dependence on machine operating circumstances, human interference, and expert abilities. In AI based techniques, various machine learning (ML) and deep learning (DL) techniques have been successfully applied for fault diagnosis of various rotating machines. From last half decade DL have been gaining popularity due to its attractive characteristic of automated feature learning and solving big data, unbalanced data, big computational burden and over-fitting problems of conventional ML techniques. Advances in DL methodologies have prompted interest in DL based intelligent fault diagnosis in the industry in the last five to 6 years. This review paper summarizes recent research and developments on DL based fault diagnosis in the last five to 6 years for various critical rotating machineries in industry such as electric motors, rotor-bearing systems, gear and gearbox, wind turbines, pumps, and compressors.

An efficient analytical approach to assess root cause of nonlinear electric vehicle gear whine

Noise, vibration, and harshness (NVH) issues pose considerable challenges for electric vehicle powertrain engineers. Gear vibrations generate an intrusive gear whine noise, with significant impact on the sound quality of electric powertrains. Dynamic transmission error (DTE) is the most quantitative indicator for gear NVH. Backlash, time variable meshing stiffness and damping contribute to DTE. Hence, a better understanding of these excitation sources is essential. A gear tribodynamics model is developed using potential energy method to estimate time variable meshing stiffness (TVMS). A fully analytical time-efficient model is proposed for lubricated contact stiffness based on transitions in the regimes of lubrication. The model accounts for the combined effects of surface elasticity and lubricant stiffness. Film thickness and damping coefficients are transiently updated at each instant during meshing cycle. The predictions from this model are compared with measured results from the literature and predicted results from Hertz contact model. The lubricated contact model successfully shows the contribution of the lubricant stiffness to TVMS and its variations with elasticity and viscosity parameters during meshing cycle. Gear harmonic and super-harmonic resonances are accurately estimated in terms of amplitude, frequencies and stiffness softening nonlinearities. Time history responses and phase-displacement diagrams show good agreement with the gear dynamics response at the main harmonic and second super-harmonic frequencies. The proposed model has a reasonable accuracy, significantly better than those from Hertzian contact models, and is considerably time efficient in comparison to numerical EHL solvers.

State of the art of Multiport Electrical Machines and Magnetic Gears with respect to Wind Power Generation Application

This paper presents a state of the art of multiport machines and magnetic gears designed for power generation applications. A multiport machine consists mainly of an electrical machine wo which a magnetic gear is integrated. Thus, one can get a device with more than two shafts, capable to operate at different levels of torque and speed. The main structures found in the literature, their operation, speed increase capability, materials, advantages and disadvantages are depicted in this review-type paper.

Оценка долговечности и рациональное крепление кожуха зубчатой передачи к тяговому двигателю электровоза

Purpose: To investigate the dependence of workload of an electric locomotive gear housing on the parameters of its attachment to a traction motor. To determine own oscillation frequencies under various conditions of its attachment to a traction motor. To propose technical solution allowing to reduce the workload of gear housing in the case of abnormal operation of its attachment to a traction motor. To propose an algorithm for housing lifetime calculation taking into account its fastening parameters. Methods: The values of gear housing own frequencies are obtained by solving the system of Lagrange differential equations of the second kind. Created with this purpose mathematical model of mechanical system under consideration takes into account an elastic nature of housing attachment to a traction motor. Results: The influence of conditions and parameters of gear housing attachment to a traction motor on its workload and, correspondingly, its lifetime is shown. The algorithm for gear housing lifetime calculation is proposed, taking into account its fastening conditions and parameters. The significant influence of workload abnormal modes on housing durability is shown. Practical importance: Constructive solution is proposed that reduces gear housing workload in the case of abnormal conditions of attachment to a traction motor. The algorithm for estimating gear housing durability in the case of redistribution of workloads between its reference points has been developed.

Optimization of powered wheels for commercial aircraft and design of test scheme

Electric landing gear drives equipped with traction motors are able to power the wheels of single-aisle commercial aircraft to provide the capability of taxiing on the ground. The powered wheels are utilized to solve the problems of low engine efficiency, high fuel consumption and high pollution of the aircraft during the taxiing process. The powered wheel electric drive system consists of an electric traction motor, a set of planetary gear assembly, and a wheel. This paper optimizes the parameters of the planetary gear assembly of the electric drive system to improve the outputted torque of the powered wheel. After that, two test schemes are designed for the powered wheel electric drive system to measure its torque. These two test schemes use moment of inertia and resistance loading to replace the actual vertical load of the aircraft applied on the powered wheel during the taxiing process. The first scheme uses the mass block to simulate the mass of the general aircraft, whereas the second scheme uses a flywheel with a variable moment of inertia to simulate the mass of large commercial aircraft.

Simulation of Runway Irregularities in a Novel Test Rig for Fully Electrical Landing Gear Systems

The E-LISA research project, under way within the Clean Sky 2 framework, has the objective of developing an innovative iron bird dedicated to executing tests on the landing gear of a small aircraft transport equipped with an electro-mechanical landing gear and electrical brake. Such tests include the simulation of complete landing procedures under different operating conditions such as runway friction, presence of periodical defects along the runway, variable aircraft weight, and approach speed. To this end, the iron bird requires novel solutions in both its architecture and its control scheme. This paper details an innovative solution that is being implemented in the E-LISA iron bird to enable the execution of tests on a landing gear, reproducing the effects of any type of runway irregularity. First, the rig architecture is presented in detail, with particular care toward the hybrid position/force control system that manages its operations. Then, a simulation model is introduced with the objective of verifying the control system stability and the test rig capability to reproduce on the test articles the effects produced on the landing gear leg of periodical runway irregularities. Simulations results are presented, highlighting the stability of the proposed control scheme and providing a preliminary assessment of the system performances.

Shaft Design for Electric Go-kart

This article presents the results of work related to the design, analysis, and manufacturing of the shaft for an electric go-kart. Works considered the stiffness of the shaft for various conditions affecting the vehicle while driving. In the previous stage of the project, the electric motor and gear transmission were selected. The main goal of this case study was to design the shaft for 10 kW electric go-kart. The rear driving axle of the go-kart is not equipped with a differential. The equal rotational speed of two rear wheels causes that occurs skidding and greater forces acting on the vehicle and driver when cornering. We were considering two types of the shaft – full and drilled. The first one provides greater stiffness, the second one is “softer”. The analysis allowed for the selection of a more appropriate shaft, and then for its manufacture and assembly in the vehicle.

Electrical and Mechanical Technology from the Perspective of EV drive system, e-axle

This paper reports the e-axle systems used in electric vehicles (EV). The e-axle system consists of the electric motor, inverter, and gear. By integrating these components in a compact unit, the drive system becomes cheaper, more compact, and more efficient and directly powering the vehicle's axle. Actually, some e-axle system achieves about 20% weight re-duction by system integration in one single system housing and 30% cost reduction by eliminating component such as expensive connecting cables. The e-axle systems can be adapted to many types of vehicles. In other words, the e-axle can be fitted to the front and/or rear axles of EV. Therefore, the author surveys the target specifications and futures of the e-axle system. The main target of the e-axle system was 150 kW systems. And there are some research barriers in the electronics and/or mechanical fields.

A new fish-based index of biotic integrity for lowland rivers in Flanders (Belgium)

The first fish-based index to assess the ecological quality of lowland rivers in Flanders (Belgium) is based on data obtained from different fishing techniques without considering the gear specificity. As a consequence, this index could not be intercalibrated with other European indices which concentrate on one gear type only. In order to comply with the European Water Framework Directive, we developed a new fish-based index using data obtained from surveys in rivers with electric gear only. All 293 selected rivers belonged to the bream or barbel zone. An updated reference list of fish species was compiled based on previous work and recent data. Abiotic data were collected according to standard methods and habitat quality of all surveyed sites was pre-classified using pressure indicators. To develop the new index candidate metrics were selected from the literature and metric values were calculated. Linear mixed regression models selected metrics based on their response to the pre-classified habitat status. Correlation tests were performed to avoid redundancy among responsive metrics. Boundaries for metric scores were defined based on the calculated metric values. The new index of biotic integrity (IBI) was calculated by summation of the metric scores, and transformed to an ecological quality ratio (EQR), ranging between 0 and 1. Five integrity classes, ranging from bad to maximal ecological potential, were attributed and compared to the pre-classified habitat status of the site. In addition, the new index was also validated with an independent set of data. The new IBI proved to successfully assess the ecological status of the rivers.

Efficiency Evaluation of Electric Bicycle Power Transmission Systems

In this study, a method for estimating the efficiency of electric bicycle power train systems consisting of typical components, such as an electric motor, gears, sprockets, and chains is presented. In order to calculate the efficiency of a power train system, the relationship between the drive motor torque and the road-load that is exerted on the rear wheel was derived, considering kinematic inertia effects and friction losses between power transmission elements. Among the factors that influence efficiency, it was found that friction losses play a dominant role, while the effects of inertia are insignificant. The factors that influence the efficiency of electric bicycles due to friction losses, such as the transmission efficiency of the chain system and the bearing in the sprocket and wheel, were quantified. To validate the proposed efficiency calculation procedure, an experimental electric bicycle was used, in which the driving torque and road-load could be quantitatively assessed, and the actual efficiency was measured on a chassis dynamometer. It is shown that for a given motor torque, a measured and estimated dynamometer torque obtained by the proposed method exhibits a good correlation, and the transmission efficiency of each component was quantified. This method provides a practical and accurate means to calculate the drive train efficiency of electric bicycles at the design stage to improve the efficiency of electric bicycles.

Research on the influence of backlash and bearing clearance on torsional vibration of pure electric vehicle gear system

Research on the influence of backlash and bearing clearance on torsional vibration of pure electric vehicle gear system

Research on the influence of backlash and bearing clearance on torsional vibration of pure electric vehicle gear system

Research on the influence of backlash and bearing clearance on torsional vibration of pure electric vehicle gear system