Dissertations / Theses on the topic 'Regenerative brake'

on mechanical brakes. The electric regenerative brakes can thus be used as normal service brake with minimum time loss.The first part of the study aims at developing a method to calculate wear on train brake pads. This is done by using a reformulated version of Archard’s wear equation with a temperature dependent wear coefficient and a temperature model to predict the brake pad temperature during braking. The temperature model is calibrated using trustworthy data from a brake system supplier and full-scale test results.By performing simulations in the program STEC (Simulation of Train Energy Consumption), energy consumption for different cases of high-speed train operations is procured and significant data for the wear calculations are found. Simulations include both “normal driving techniques” and “eco driving”. The driving styles were decided through interviews with train drivers and experts on energy optimized driving systems.The simulations show that more powerful drive systems reduce both energy consumption and travel time by permitting higher acceleration and energy regeneration while braking. Calculations show that since the electric motors could carry out more of the braking the wear of the mechanical brakes becomes lower.Eco driving techniques can help to further reduce the energy consumption and mechanical brake wear. This driving style can require some time margins though, since it takes slightly longer time to drive when using coasting and avoiding speed peaks. However, if used properly this should not have to affect the actual travel time, partly because some time margins are always included in the timetable.Even if new, more powerful, trains would have the ability to reduce energy consumption and brake wear it is also necessary to have an appropriate slip control system for the electric brakes, making it possible to use them also under slippery conditions. In this context it is important that the adhesion utilization is modest, about 12 – 15 % for speeds up to 100 km/h and lower at higher speeds.

The air hybrid engine absorbs the vehicle kinetic energy during braking, stores it in an air tank in the form of compressed air, and reuses it to start the engine and to propel a vehicle during cruising and acceleration. Capturing, storing and reusing this braking energy to achieve stop-start operation and to give additional power can therefore improve fuel economy, particularly in cities and urban areas where the traffic conditions involve many stops and starts. In order to reuse the residual kinetic energy, the vehicle operation consists of 3 basic modes, i.e. Compression Mode (CM), Expander Mode (EM) and normal firing mode, as well as stop-start operation through an air starter. A four-cylinder 2 litre diesel engine has been modelled to operate in four air hybrid engine configurations so that the braking and motoring performance of each configuration could be studied. These air hybrid systems can be constructed with production technologies and incur minimum changes to the existing engine design. The regenerative engine braking and starting capability is realised through the employment of an innovative simple one-way intake system and a production cam profile switching (CPS) mechanism. The hybrid systems will allow the engine to be cranked by the compressed air at moderate pressure without using addition starters or dedicated valves in the cylinder head. Therefore, the proposed air hybrid engine systems can be considered as a cost-effective regenerative hybrid powertrain and can be implemented in vehicles using existing production technologies. A novel cost-effective pneumatic regenerative stop-start hybrid system, Regenerative Engine Braking Device (RegenEBD), for buses and commercial vehicles is presented. RegenEBD is capable of converting kinetic energy into pneumatic energy in the compressed air saved in an air tank using a production engine braking device and other production type automotive components and a proprietary intake system design. The compressed air is then used to drive an air starter to achieve regenerative stop-start operations. The proposed hybrid system can work with the existing vehicle transmission system and can be implemented with the retro-fitted valve actuation device and a sandwich block mounted between the cylinder head and the production intake manifold. Compression mode operation is achieved by keeping the intake valves from fully closed throughout the four-strokes through a production type variable valve exhaust brake (VVEB) device on the intake valves. As a result, the induced air could be compressed through the opening gap of intake valves into the air tank through the intake system of proprietary design. The compressed air can then be used to crank the engine directly through the air expander operation or indirectly through the action of an air starter in production. A single cylinder camless engine has been set up and operated to evaluate the compression mode performance of two air hybrid concepts. The experimental results are then compared with the computational output with excellent agreement. In order to evaluate the potential of the air hybrid engine technologies, a new vehicle driving cycle simulation program has been developed using Matlab Simulink. An air hybrid engine sub-model and methodology for modelling the air hybrid engine’s performance have been proposed and implemented in the vehicle driving cycle simulation. The NEDC analysis of a Ford Mondeo vehicle shows that the vehicle can achieve regenerative stop-start operations throughout the driving cycle when it is powered by a 2.0litre diesel engine with air hybrid operation using a 40litre air tank of less than 10bar pressure. The regenerative stop-start operation can lead to 4.5% fuel saving during the NEDC. Finally, the Millbrook London Transport Bus (MLTB) driving cycle has been used to analyse the effectiveness of RegenEBD on a double deck bus powered by a Yuchai diesel engine. The results show that 90% stop-starts during the MLTB can be accomplished by RegenEBD and that a significant fuel saving of 6.5% can be obtained from the regenerative stop-start operations.

All electric machines have two mechanical operations, motoring and braking. The nature of braking can be regenerative, where the kinetic energy of the rotor is converted into electricity and sent back to the power source or non-regenerative, where the source supplies electric power to provide braking. This thesis investigates several critical issues related to regenerative braking in both DC and AC electric machines, including the determination of boundaries in the torque-speed plane defining the regenerative braking capability region and the evaluation of operating points within that capability region that result in maximum regenerative braking recharge current. Electric machines are used in the powertrains of electric and hybrid-electric vehicles to provide motoring or braking torque in response to the driver's request and power management logic. Since such vehicles carry a limited amount of electrical energy on-board their energy storage systems (such as a battery pack), it is important to conserve as much electrical energy as possible in order to increase the range of travel. Therefore, the concept of regenerative braking is of importance for such vehicles since operating in this mode during a braking event sends power back to the energy storage system thereby replenishing its energy level. Since the electric machine assists the mechanical friction braking system of the vehicle, it results in reduced wear on components within the mechanical friction brake system. As both mechanical friction braking and electric machine braking are used to provide the requested vehicle braking torque, braking strategies which relate to splitting of the braking command between the two braking mechanisms are discussed. The reduction in energy consumption of a test vehicle along different driving schedules while using different braking strategies is also studied.

One of the benefits of electric vehicles (EVs) and hybrid vehicles (HVs) is their potential to recuperate braking energy. Regenerative braking (RB) will minimize duty levels on the brakes, giving advantages including extended brake rotor and friction material life and, more significantly, reduced brake mass and minimised brake pad wear. In this thesis, a mathematical analysis (MATLAB) has been used to analyse the accessibility of regenerative braking energy during a single-stop braking event. The results have indicated that a friction brake could be downsized while maintaining the same functional requirements of the vehicle braking in the standard brakes, including thermomechanical performance (heat transfer coefficient estimation, temperature distribution, cooling and stress deformation). This would allow lighter brakes to be designed and fitted with confidence in a normal passenger car alongside a hybrid electric drive. An approach has been established and a lightweight brake disc design analysed FEA and experimentally verified is presented in this research. Thermal performance was a key factor which was studied using the 3D model in FEA simulations. Ultimately, a design approach for lightweight brake discs suitable for use in any car-sized hybrid vehicle has been developed and tested. The results from experiments on a prototype lightweight brake disc were shown to illustrate the effects of RBS/friction combination in terms of weight reduction. The design requirement, including reducing the thickness, would affect the temperature distribution and increase stress at the critical area. Based on the relationship obtained between rotor weight, thickness and each performance requirement, criteria have been established for designing lightweight brake discs in a vehicle with regenerative braking.

Orientador: Auteliano Antunes dos Santos Júnior
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-16T12:30:34Z (GMT). No. of bitstreams: 1 Santos_AliandroHenriqueCosta_D.pdf: 8979890 bytes, checksum: bb6cc54449e1618ad7164f703818f79b (MD5) Previous issue date: 2009
Resumo: A tendência nas grandes metrópoles é de substituir a frota de veículos à combustão por veículos elétricos e híbridos. Estes veículos, em geral, usam banco de baterias como fonte de energia de mobilidade, preservando o meio ambiente, além de armazenar a energia gerada pelo motor durante as frenagens regenerativas, economizando energia. Tais sistemas de frenagens são auxiliados por módulos de ultracapacitores, que absorvem os picos de potência, preservando a vida útil das baterias. Com o avanço mundial no setor automobilístico, novas tecnologias têm surgido e com isto, a solicitação do sistema por atrito durante as frenagens tem sido preservada ou ampliada. O esforço de frenagem em veículos elétricos e híbridos é compartilhado entre os sistemas por atrito e regenerativo. Este trabalho teve como objetivo avaliar a possibilidade de utilização de diferentes materiais de atrito de pastilhas de freio comerciais para aplicações com frenagem regenerativa em veículos elétricos ou híbridos. Para a realização dos experimentos foi utilizado um dinamômetro especialmente desenvolvido, instalado no Departamento de Projeto Mecânico da FEM - Unicamp. Um planejamento experimental fatorial fracionário permitiu o estudo da influência de variáveis envolvidas na avaliação do comportamento do coeficiente de atrito, que são a porcentagem de frenagem mecânica e elétrica, a desaceleração, a velocidade e a temperatura. Os resultados experimentais mostram que o procedimento proposto pode ser utilizado para identificar a pastilha mais adequada, ou seja, a que apresenta a menor variação do coeficiente de atrito
Abstract: The tendency in large cities is to replace the fleet of engine operated vehicles by electric and hybrid vehicles. These vehicles generally use a bank of batteries as the mobility energy source, preserving the environment and storing the energy generated by the motor during the regenerative braking, saving energy. Such braking systems are aided for modules of ultracapacitors, which absorb the peaks of power, preserving the life of batteries. With the world advances in automobile engineering, new technologies have emerged and with this, the request of the system by friction during the braking has been preserved or even increased. Brake efforts of electric and hybrid vehicles are shared between the friction and regenerative systems. This work aimed to evaluate the possibility of using different materials of friction for commercial brake pads applied with regenerative braking systems of electric and hybrid vehicles. The experiments were performed using a specially developed dynamometer installed in the Department of Mechanical Design - FEM at University of Campinas, Brazil. A fractional factorial design was used to take the factor of influences in account. They are identified and the main factors are: percentage of electrical and mechanical braking, deceleration, sliding speed and temperature. The experimental results show that the procedure can be used to identify the more suitable material, which presents the smallest variation of friction coefficient
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica

The research looks at the advantages and disadvantages of a hydraulic auxiliary drive (HAD) system which is installed on a 25 meter long timber transport vehicle. The purpose is to investigate the performance with regard to energy, economy and environment of the system due to the added components, the hydraulic accumulators. The auxiliary system that is used on the vehicle is simply a hydrostatic transmission system. Ideally, the fuel consumption and cost can be reduced by using accumulators. To verify this hypothesis, model-based simulations were performed in a software environment and the result was analyzed for a linear and repeatedly accelerating and decelerating driving cycle. Additionally, comparisons were made between the HAD system with and without the assistance of accumulators. From the simulation results, the system assisted by accumulators consumes approximately 14% less fuel than the other. And it produces 15% more tractive effort when the vehicle is accelerating. The paper also includes the determination of the size of accumulators, both theoretically and with simulations. By comparison, there is a small difference between the results from the theoretical calculation and the simulations, which might be caused by a neglecting the volumetric losses in the simulation process. Ideally, an accumulator with a size of 57 L was found to be the most efficient size for the studied driving cycle. Beyond that speed, the efficiency will decrease to some extent. Physical tests are not presented in this paper, but they will be done in the future.
Den presenterade forskningen studerade fördelar och nackdelar med ett hydraulisk hjälpsystem för fordonsdrift (HAD) för en 25 meter lång timmerlastbil. Syftet var att undersöka hur drivlinans prestanda med avseende på energy, ekonomi och miljöpåverkan, påverkas av de adderade komponenterna, de hydrauliska ackumulatorerna. Hjälpsystemet är helt enkelt ett hydrostatiskt transmissionssystem. Idealt, kan bränsleförbrukning och kostnad reduceras genom att använda ackumulatorer i systemet. För att verifiera denna hypotes, har modell-baserade simuleringar utförts och resultaten har analyserats för konstantfartskörning och en körcykel med upprepade accelerationer och inbromsningar. Dessutom, har ett HAD-system med och utan ackumulator jämförts. Simuleringsresultaten visar att ett system med ackumulatorer förbrukar ca 14% mindre bränsle än ett system utan ackumulatorer. Ett ackumulatorstött system ger också 15% högre framdrivningseffekt vid accelereration. I avhandlingen dimensionera också storleken på ackumulatorerna, både teoretiskt och med simuleringar. Det finns en liten skillnad mellan resultaten från den teoretiska beräkningen och simuleringarna, som kan bero på att volymetriska förlusterna inte har tagits med i simuleringarna. En ackumulator med en storlek på 57 L visar sig ha den mest effektiva storleken för den studerade körcykeln. Vid högre körhastigheter, kommer verkningsgraden att minska till viss del. Inga fysiska tester har gjorts, men de kommer att utföras i framtiden.

In this work, a proposal for BLDC motor control, which will be used as a drive linear actuator. Control with microcontroller focuses mainly aspects such as motor mode, regenerative mode, measuring rotor position sensors and measuring the motor current, which corresponds to the moment. The result of the work is focused on upgrading the existing Honeywell actuator, where the processor-controlled BLDC motor to replace the existing system and take over the actuator working function and emergency function.

碩士
國立中興大學
電機工程學系所
106
Looking at the global energy trends and the government policies in Taiwan, electric vehicles are expected to replace gasoline vehicles in the near future. Although electric vehicle technology has been perfect and widespread in recent years, most of the braking systems still use mechanical discs or drum brakes. In addition, the current driving system and the braking system are two independent modules. In this thesis, an integrated driving and braking control system are designed for electric vehicle with active regenerative braking control system. For example when there is no driving current entering the motor stator, and the motor is remaining inertial rotation. The motor becomes a generator with current generated in the opposite direction relative driving current. By using this feature, the back electromagnetic field (EMF) controlled by the pulse-width modulation (PWM) technique to charging a capacitor. The capacitor as an extra energy source is cascaded with the battery as a charge pump. This is used to present excessive braking torque to stop the rotating motor in an efficient way. This thesis proposes that the back EMF can regenerate the charging capacity combined with the reverse magnetic field braking method. We integrated the controller of driving system and braking system. Extensive experimental was conducted to verify the proposed design. Comparing with the resistance brake and capacitive brake, the active regenerative control system is most efficient.

碩士
國立臺北科技大學
車輛工程系所
102
This study proposes a novel method of the electric brake with energy-regeneration for the brushless DC motor (BLDCM) of the electric scooter (E-Scooter). The proposed method could convert the kinetic energy into the electric one to recover the battery during the braking period. Thus, the driving range of the electric scooter can be increased by the method of the energy-regeneration; furthermore, the safety and comfort of the driver could be improved by the electric brake. The proposed method could change the switching signals of motor driver to control the inverse torque during the braking period. Compared with the presented methods, the proposed solution achieves the goal of the energy-regeneration without additional converter or changing windings of the motor stator. In addition to the braking period, the period of release throttle is included in the energy-regeneration mechanism such that the electric scooter has a similar function of the engine brake for the driving safety. Furthermore, the battery may be injured by the surge regeneration current in the high speed duration. Therefore, the proposed strategy could control the current to protect the battery and provides a smooth and reliable brake. The system drives electric vehicles of the variable winding motor, while analyses the wye connected status and delta connected state.

碩士
國立成功大學
電機工程學系專班
97
This paper presents the design of regenerative brake system for AC Servo Driver based on Fuzzy algorithm. The main drawback of traditional application is that a brake system built in an AC servo driver is triggered under a fixed detection level of PN-BUS voltage, which causes malfunction occasionally, and therefore burns out the internal brake resistor. In order to reduce the probability of malfunction of braking controller and improve the accuracy of the regenerative braking system, the fuzzy algorithm is considered a solution in this paper. The experimental results show that fuzzy algorithm-based application proposed in this paper not only can achieve a significant variable duty detection level on PN-BUS voltage, but also works in a firmware-based operation to avoid from resistors burnout.

碩士
國立臺北科技大學
車輛工程系所
99
This thesis studies a brushless DC motor controller with regenerative-brake of intelligent energy management for electric vehicle (EV). Under the considerations of the battery protection, smooth braking torque and driving safety, the controller will convert the kinetic energy into the electric one to recover the battery, when the driver inputs the braking command by pressing the braking holder on the electric vehicle. The proposed method with intelligent management only changes the switching sequence of the inverter to control the inverse torque and fill the driver’s need for safe brake, besides, the braking energy will return to the battery. The proposed solution could achieve the goal of the regenerative-brake which is not only need not to change the circuit of the inverter or the structure of the complex winding-changeover but also need not add converter or ultracapacitor. About the management strategy of the regenerative-brake energy, this thesis adopts fuzzy control algorithm to implement it. Compared with the presented methods, the proposed control strategy could obtain more regenerative current to achieve the increase of the energy efficiency in addition to the basic goals of the electric brake and the energy regeneration. Finally, the feasibility of the proposed method is demonstrated by experimental results. It shows that the driving range of the EV could be increased to about 31％.

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Regenerative braking would extend the working range of an EV or HV provided that any extra energy consumption from increased vehicle mass and system losses did not outweigh the saving from energy recuperation, also reduce duty levels on the brakes themselves, giving advantages including extended brake rotor and friction material life, but more importantly reduced brake mass, minimise brake pad wear. The objective of this research is to define thermal performance on lightweight disc brake models. Thermal performance was a key factor which was studied using the 3D model in FEA simulations. Ultimately a design method for lightweight brakes suitable for use on any car-sized hybrid vehicle was used from previous analysis. The design requirement, including reducing the thickness, would affect the temperature distribution and increase stress at the critical area. Based on the relationship obtained between rotor weight, thickness, undercut effect and offset between hat and friction ring, criteria have been established for designing lightweight brake discs in a vehicle with regenerative braking.

Hybrid electric vehicle technology has become a preferred method for the automotive industry to reduce environmental impact and fuel consumption of their vehicles. Hybrid electric vehicles accomplish these reductions through the use of multiple propulsion systems, namely an electric motor and internal combustion engine, which allow the elimination of idling, operation of the internal combustion engine in a more efficient manner and the use of regenerative braking. However, the added cost of the hybrid electric system has hindered the sales of these vehicles. A more cost effective design of an electro-hydraulic braking system is presented. The system electro-mechanically controlled the boost force created by the brake booster independently of the driver braking force and with adequate time response. The system allowed for the blending of the mechanical and regenerative braking torques in a manner transparent to the driver and allowed for regenerative braking to be conducted efficiently. A systematic design process was followed, with emphasis placed on demonstrating conceptual design feasibility and preliminary design functionality using virtual and physical prototyping. The virtual and physical prototypes were then used in combination as a powerful tool to validate and develop the system. The role of prototyping in the design process is presented and discussed. Through the experiences gained by the author during the design process, it is recommended that students create physical prototypes to enhance their educational experience. These experiences are evident throughout the thesis presented.

碩士
國立成功大學
工程科學系碩博士班
98
Recently, since people changing their live style in many aspects, the living standard is as higher as possible and the gasoline is greatly consumed. According to statistic from BP Statistical Review, the index of reserved gasoline can only provide about 36~43 years. By the reason, human must develop new energy source which is sustainable and less environmental pollution in following decade. At this time, many researches are working on decreasing the gasoline-consuming efficiently to energy-saving. Since vehicles consumed numerously gasoline, improve these vehicles to energy-saving is important. Electric vehicle (EV) replaced internal combustion engine (ICE) by electric motors is more popular in the world. However, EVs are hard to popularize since the sustainability is lower than it with internal combustion engine. This defect is unacceptable for user to buy or use EVs widely. Therefore, increase the sustainability of EV is a novel research topic. In generally, the conventional brake applies the friction to decrease the vehicle’s speed, and translate the kinetic energy to heat. The energy is just consumed. In order to recycle the kinetic energy in braking process, regenerative brake method is presented. Regenerative brake translates the kinetic energy to electric energy by utilizing the motor’s back-EMF and internal winding. The method controls the switch sequences of MOSFETs to elevate the back-EMF voltage and recharge the battery. In the meanwhile, the motors operate in braking mode, and produce an inverse torque to reduce the motor’s speed. Depend on the regenerative brake method, the motors drive can accomplish brake function and extending traveling distance without adding any component. “Extending the traveling distance” and “Control the regenerative current” are the topics of this thesis. Since the brake torque is depended on the recharge current, a current control in EVs with self-tuning fuzzy neural network algorithm is proposed. The gradient descent and back-propagation are used to adjust the parameters of fuzzy neural network, and minimize the current error. Finally, Lyapunov’s stability theorem is applied to prove the system stability. Finally, the microprocessors dsPIC30f2010 by Microchip, are employed to implement the proposed control algorithms. The driving and braking mode are tested on a motive machine and inertial instrument. Moreover, the implemental results of the proposed system set up on EVs demonstrate the ability of recharge and the feasibility of regenerative brake.