Design and integration of a dynamic IPT system for automotive applications

Inductive power transmission (IPT) for electric vehicles (EVs) is a promising emergent technology that seems able to improve the electric mobility acceptance. In the last two decades many researchers have proved its feasibility and the possibility to use it to replace the common conductive systems for the charge of the on-board battery. Many efforts are currently aimed to extend the IPT technology towards its use for the charge during the vehicle motion. This application, commonly indicated as dynamic IPT, is aimed to overcome the limit represented by the long stops needed for the recharge introducing also the possibility of reducing the battery capacity installed on vehicle. An IPT system is essentially based on the resonance of two magnetically coupled inductors, the transmitter, placed on or under the ground, and the receiver, placed under the vehicle floor. The typical operating frequency range for the EVs application goes from 20 kHz to approximately 100 kHz. The coupling between the two inductors takes place through a large air-gap, usually about 10-30 cm. This thesis presents the results of the research activities aimed to the creation of a prototype for the dynamic IPT oriented to the private transport. Starting from an analysis of the state of the art and the current research projects on this domain, this work presents the development of a circuit model able to describe the electromagnetic phenomena at the base of the power transfer and the interface with the power electronics. This model provides the information at the base of the design and the implementation of a dedicated low cost-high effciency H-bridge converter for the supply of the transmitter side. A general architecture of the power electronics that manages the receiver side is proposed together with the additional protection circuits. A methodology for the integrated design of the magnetic structure is illustrated covering the aspects of the matching with the power electronics, the integration on an existing vehicle and the installation on the road infrastructure. A series of activities aimed to the implementation of a dedicated test site are presented and discussed. In particular, the activities related to the creation of the electrical infrastructure and the issues and methods for the embedding of the transmitters in the road pavement are presented. The final goal is the creation of a dedicated IPT charging line one hundred meters long. Finally, a methodology for the assessment of the human exposure is presented and applied to the developed solution

Capacitor for resonant circuits in power applications

A capacitive element is manufactured by using the multilayer printed circuit board technology . The body of the element includes a layer of dielectric material interposed between two layers of conductive material arranged on opposite sides of the layer of dielectric material . Each layer of conductive material is in turn covered , on its free side , with an external covering layer . The material for making the layer of dielectric material is chosen among materials having : a dielectric permeability epsilon_r > 1 , a dielectric rigidity k > 100 kV / mm , and a loss figure Df<=0.002 . Furthermore , the dimensions of the layer of dielectric material are greater than the dimensions of the layers of conductive material , so as to limit the edge effects that might cause discharge phenomena and make the capacitive element flexible

Inductive power transfer for automotive applications: State-of-the-art and future trends

The paper discusses the status of the development status of the inductive power transmission for automotive applications. This technology is, in fact, gaining the interest of electric vehicle manufacturers as an effective strategy to improve the market penetration of electric mobility. Starting from the origin of this technology, the paper presents an overview of the current state-of-the-art as well as the current research and industrial projects. Particular attention is devoted to the description of a prototypal system for the dynamic inductive power transmission whose goal is to extend the battery range by a fast partial recharging during the movement of the vehicle

ELECTRO-MECHANICAL DESIGN OF A MAGNETIC GEAR PROTOTYPE

A magneto-mechanical approach is proposed to design a magnetic gear prototype. Firstly, an integrated tool for electromechanical simulations is developed, starting from a topological parametric model of a planetary magnetic gear (PMG). Then a CAD model is realised with a progressive rise in complexity, in order to achieve quickly exchangeable configurations for different experimental tests. Three different solutions are designed with advantages and drawbacks. Finally, a block-oriented dynamic model of a PMG, inserted in a mechanical driveline, is developed in Matlab/Simulink environment using the results of magneto mechanical simulations, to virtually test the dynamic behaviour of the device

Fast hardware protection for a series-series compensated inductive power transfer system for electric vehicles

The paper proposes a simple solution to a safety problem encountered during the development of a series-series compensated IPT system for electric vehicles. This problem is related to the equivalent current source behavior of the receiver side in presence of an unpredicted load disconnection. A pure analog hardware system able to manage this fault protecting the filtering elements of the system is proposed. The system is investigated by means of a circuit simulation then its physical implementation is presented. The effectiveness of the proposed solution is experimentally proven

Theoretical and experimental comparison of two interoperable dynamic wireless power transfer systems for electric vehicles

The paper discusses two wireless power transfer systems for the charge of electric vehicles during the motion. The systems are conceived to be interoperable with the same receiver structure. Both systems are supplied by means of the same power electronics architecture and are based on the series-series compensation of the coils. In one of the presented systems a high-frequency transformer is used at the transmitter side. The two solutions are analyzed and compared pointing out their advantages and drawbacks. Results of experimental tests are presented to demonstrate the operations of both systems

Efficient management of industrial electric vehicles by means of static and dynamic wireless power transfer systems

Industrial companies are moving toward the electrification of equipment and processes, in line with the broader energy transition taking place across the economy. Particularly, the energy efficiency and, consequently, the reduction of environmental pollution of intralogistics activities have become a competitive element and are now an actual research and development objective. A wireless power transfer is a contactless electrical energy transmission technology based on the magnetic coupling between coils installable under the ground level and a coil mounted under the vehicle floor, and it represents an excellent solution to decrease the demand for batteries by reducing vehicle downtimes during the recharge. This work aims to define a methodology to determine the optimal positioning of wireless charging units across the warehouse, both for static and dynamic recharging. To this aim, firstly, a mathematical model of the warehouse is proposed to describe transfers and storage/retrieval operations executed by the forklifts. Then, an integer linear programming problem is applied to find the best possible layout of the charging infrastructures. The optimal solution respects the energetic requirements given by the customer and minimizes the overall system cost. The proposed approach was applied to optimize the installation in a real-size warehouse of a tire manufacturing company. Several scenarios were computer generated through discrete event simulation in order to test the optimizer in different warehouse conditions. The obtained results show that integrated dynamic and static WPT systems ensure a constant state of charge of the electric vehicles during their operations

Design of an Integrated, Six-Phase, Interleaved, Synchronous DC/DC Boost Converter on a Fuel-Cell-Powered Sport Catamaran

This paper describes the preliminary analysis, design and implementation phases of a DC/DC boost converter dedicated to the Futura catamaran propulsion chain developed by the UniBoAT team at the University of Bologna. The main goal of the project was the reduction of the converter’s weight by eliminating the use of heat sinks and by reducing the component size, especially inductors and capacitors. The obtained converter is directly integrated into the structure containing the fuel-cell stack. The realized converter was based on an interleaved architecture with six phases controlled through the average current mode control. The design was validated through simulations carried out using the LT-Spice software, whereas experimental validations were performed by means of both bench tests and on-field tests. Detailed thermal and efficiency analyses were provided with the bench tests under the two synchronous and non-synchronous operating modes and with the adoption of the phase-shedding technique. Prototype implementation and performance in real operating conditions are discussed in relation to on-field tests. The designed converter can be used in other applications requiring a voltage-controlled boost converter

Sensorless control of the charging process of a dynamic inductive power transfer system with interleaved nine-phase boost converter

The paper proposes a technique for the control of the charging process in a dynamic inductive power transfer system for automotive applications. This technique is based on an impedance control loop on the receiver side. The proposed control allows to carry out the different phases of the charging process in absence of a communication link between ground and vehicle side. The charging process starts with a sensorless procedure for the identification of the actual presence of the vehicle over the receiver. The same control technique introduces several advantages in terms of interoperability between systems having different requirements in terms of power demand. A 11 kW prototype has been implemented based on a transmitter 1.5 meters long as compromise solution between the long track coil and the lumped one. The power management of the receiver side is provided by a nine-phase interleaved boost converter. The experimental results prove the effectiveness of the proposed control together with a good matching with the developed theoretical equations set for the system description

Design of Wireless Power Transmission for a Charge While Driving System

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