Passenger Exposure to Magnetic Fields due to the Batteries of an Electric Vehicle

In electric vehicles, passengers sit very close to an electric system of significant power. The high currents achieved in these vehicles mean that the passengers could be exposed to significant magnetic fields. One of the electric devices present in the power train are the batteries. In this paper, a methodology to evaluate the magnetic field created by these batteries is presented. First, the magnetic field generated by a single battery is analyzed using finite elements simulations. Results are compared to laboratory measurements, taken from a real battery, in order to validate the model. After this, the magnetic field created by a complete battery pack is estimated and results are discussed

Desain Sistem Pengereman Regeneratif Pada Sepeda Listrik Ringkas

Penggunaan kendaraan listrik yang semakin populer untuk mengurangi pencemaran lingkungan menuntut efisiensi penggunaan yang baik agar tujuan tersebut dapat tercapai. Penelitian diusulkan suatu metode pengereman regeneratif untuk meningkatkan efisiensi penggunaan energi dari sepeda listrik ringkas. Penelitian ini bertujuan untuk membuat suatu model dinamis dari sistem pengereman regeneratif yang diusulkan, sehingga hipotesis karakteristik efisiensi sistem pengereman dapat dibangun sebagai bahan pertimbangan dalam membuat dan mengoptimasi model fisik nantinya. Model dinamis akan disimulasikan menggunakan Simulink untuk melihat efisiensi pengereman berdasarkan kecepatan awal sepeda, selain itu pengaruh besar parameter sistem pengereman yaitu Spur Gear akan divariasikan untuk melihat variasi efisiensi. Dari hasil simulasi didapatkan bahwa nilai rugi torka yang dihasilkan dari proses pengereman sebanding dengan kecepatan awal pengereman. Di sisi lain efisiensi pengereman semakin meningkat dengan meningkatnya kecepatan awal pengereman, hal ini menandakan bahwa peningkatan rugi torka akibat peningkatan kecepatan awal pengeraman tidak memiliki sifat linear. Rasio spur gear yang tinggi memperbesar torka pengereman dan menghasilkan efisiensi yang nilainya naik jika rasio spur gear diperbesar. Hasil simulasi ini memberikan informasi awal untuk mengembangkan desain dan mengoptimasi efisiensi dan efektivitas pengerema

High-precision hydraulic pressure control based on linear pressure-drop modulation in valve critical equilibrium state

High precision and fast response are of great significance for hydraulic pressure control in automotive braking systems. In this paper, a novel sliding mode control based high-precision hydraulic pressure feedback modulation is proposed. Dynamical models of the hydraulic brake system including valve dynamics are established. An open loop load pressure control based on the linear relationship between the pressure-drop and coil current in valve critical open equilibrium state is proposed, and also experimentally validated on a hardware-in-the-loop test rig. The control characteristics under different input pressures and varied coil currents are investigated. Moreover, the sensitivity of the proposed modulation on valve's key structure parameters and environmental temperatures are explored with some unexpected drawbacks. In order to achieve better robustness and precision, a sliding mode control based closed loop scheme is developed for the linear pressure-drop modulation. Comparative tests between this method and the existing methods are carried out. The results validate the effectiveness and superior performance of the proposed closed loop modulation method

Application of Floating Pedal Regenerative Braking for a Rear-Wheel-Drive Parallel-Series Plug-In Hybrid Electric Vehicle with an Automatic Transmission

As the world continues to move further away from our reliance on fossil fuels, hybrid vehicles are becoming ever more popular. Braking is a system on both hybrid and normal vehicles that involves a significant amount of power and energy. A hybrid can recapture some of that energy using regenerative braking. In this thesis, a method is devised to blend hydraulic and regenerative braking in the most effective manner. A MATLAB Simulink model was built to simulate a parallel-series plug-in hybrid electric vehicle. The model allows for the implementation of a regenerative brake controller that utilizes floating pedal regen, custom shift logic, and brake pedal blended regen. The floating pedal controller activates regenerative braking when the driver releases the accelerator pedal. This is done by remapping the pedal based on vehicle speed, gear position, and wheel torques. The custom shift logic utilizes the motor rpm and efficiencies curves to determine when to shift the transmission. The brake pedal regen is added to the hydraulic braking based on brake pedal position. This regenerative brake controller can recharge the battery by 2% SOC during one deceleration event from 130 kph to 20 kph, while maintaining a comfortable deceleration rate less than 3m/sec^2

Almacenamiento de energía eléctrica mediante el frenado regenerativo para el sistema de transporte eléctrico masivo

Este artículo propone plantear un modelo matemático para el diseño del sistema de almacenamiento de la energía que se recupera en un vehículo, en el contexto del funcionamiento de un sistema de transporte masivo eléctrico tipo metro. Para realizar adecuadamente la tarea por medio de supercapacitores, se toman en cuenta los cambios en las magnitudes físicas que afectan directamente los consumos y recuperaciones energéticas que se obtienen por medio de simulaciones sucesivas georreferenciadas con SUMO, de tal software se obtiene la potencia requerida en cada momento del recorrido y que es dato de entrada del modelo de los elementos de almacenamiento en Simulink de Matlab. Se plantea la estrategia para determinar la cantidad de energía disponible en diferentes escenarios, mismos que modifican la forma en que han sido aplicados los frenos eléctricos regenerativos. Aspectos como la demanda que genera el transporte masivo tipo metro, el frenado regenerativo y los supercapacitores también se abordan. Los resultados de este modelo incluyen la obtención del voltaje en el sistema de almacenaje durante todo el trayecto del metro.This paper proposes a mathematical model for the design of the storage system. This system is for the energy that is recovered in a huge vehicle. The vehicle is employed on context of an electric massive transportation as a subway. In order to accomplish the task with supercapacitors, some aspects are taken into account. The physical variables that affect directly the electrical energy consumption and recovery. The energy profile is obtained through successive georeferenced simulations on SUMO. The software allows to get the power that is required on every moment of the simulated journey. This data is employed as input for the model of storage elements on Simulink. Then, the authors propose a strategy to establish the quantity of energy that is available on different type of scenarios that are established on this paper. The changes modify the way electric regenerative braking is employed. Some aspects that the authors take account include the passengers demand, acceleration, deceleration and speed of a subway. The regenerative braking and supercapacitors main characteristics are also approached. The results of math modelling include to get the voltage on the storage system during all the journey of the subway

Design and Analysis of Electric Powertrains for Offshore Drilling Applications

Doktorgradsavhandling ved Institutt for ingeniørvitenskap, Universitetet i Agder, 2016The global energy market is challenged with an ever increasing need for resources to meet the growing demands for electric power, transportation fuels, etc. Although we witness the expansion of the renewable energy industry, it is still the fossil fuels, with oil and gas dominating the scene of global energy supply sector, that provide majority of worldwide power generation.However, many of the easily accessible hydrocarbon reserves are depleted which requires from the producers of drilling equipment to focus on cost-effective operations and technology to compete in a challenging market. Particularly high level of activity is observed in both industry and academia in the field of electrical actuation systems of drilling machines, as control methods of alternating current (AC) motor drives have become an industrially mature technology over the past few decades. In addition, state-of-the-art AC motors manufacturing processes allow to conform to the strict requirements for safe operation of electrical equipment in explosive atmospheres. These two main reasons made electric actuation systems a tough competitor to hydraulic powertrains used traditionally by the industry. However, optimal design of induction motor drives and systematic analysis of factors associated with operation in harsh offshore conditions are still considered as a major challenge. In this thesis, effective methods for design and analysis of induction motor drives are proposed, including aspects of optimization and simulation-based engineering. The first part of the thesis is devoted to studying methods for modeling, control, and identification of induction machines operating in offshore drilling equipment with the focus to improve their reliability, extend lifetime, and avoid faults and damage, whereas the second part introduces more general approaches to the optimal selection of components of electric drivetrains and to the improvement of the existing dimensioning guidelines. A multidisciplinary approach to design of actuation systems is explored in this thesis by studying the areas of motion control, condition monitoring, and thermal modeling of electric powertrains with an aspiration to reach the level of design sophistication which goes beyond what is currently considered an industrial standard. We present a technique to reproduce operation of a full-scale offshore drilling machine on a scaled-down experimental setup to estimate the mechanical load that the designed powertrain must overcome to meet the specification requirements. The same laboratory setup is used to verify the accuracy of the estimation and control method of an induction motor drive based on the extended Kalman filter (EKF) to confirm that the sensorless control techniques can reduce the number of data acquisition devices in offshore machines, and thus decrease their failure rate without negatively affecting their functionality. To address the challenge of condition monitoring of induction motor drives, we propose a technique to assess the expected lifetime of electric drivetrain components when subjected to the desired duty cycles by comparing the effects of a few popular motion control signals on the cumulative damage and vibrations. As a result, the information about the influence of a given control strategy on drivetrain lifecycle is made available early in the design stage which can significantly affect the choice of the optimal powertrain components. The results show that some of the techniques that have a well-proven track record in other industries can be successfully applied to solve challenges associated with operation of offshore drilling machines. One of the most essential contributions of this thesis, optimal selection of drivetrain components, is based on formulating the drivetrain dimensioning problem as a mixed integer optimization program. The components of powertrain that satisfy the design constraints and are as cost-effective as possible are found to be the global optimum, contrary to the functionality offered by some commercially available drivetrain sizing software products. Another important drawback of the dimensioning procedures recommended by the motor drives manufacturers is the inability to assess if the permissible temperature limits given in the standards do not become violated when the actuation system experiences overloads different than these tabulated in the catalogs. Hence, the second most significant contribution is to propose a method to monitor thermal performance of induction motor drives that is based exclusively on publicly available catalog data and allows for evaluating whether the standard thermal performance limits are violated or not under arbitrary load conditions and at any ambient temperature. Both these solutions can effectively enrich the industrially accepted dimensioning procedures to satisfy the level of conservatism that is demanded by the offshore drilling business but, at the same time, provide improved efficiency and flexibility of the product design process and guarantee optimality (quantitatively, not qualitatively, measurable) of the final solution. An attractive direction for additional development is to further integrate knowledge from different fields relevant to electric powertrains to enable design of tailored solutions without compromising on their cost and performance