Contactless Electrical Energy Transmission Research Articles

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.

A Novel AC/DC Bridgeless and Contactless Electrical Energy Transmission System for Multi-load Applications

In this paper, a novel AC/DC bridge-less and contact-less energy transmission system is proposed. The coreless planar transformer and magnetic dipole moment are applied to transmit electrical energy in non-contact manner. In addition, the input ac current of proposed converter has good power factor correction. Simultaneously, the primary-side switches have zero-voltage switching and the secondary-side diodes have zero-current transition. Thus, the power quality and efficiency of proposed contactless electrical energy transmission system can be upgraded. Furthermore, the proposed contactless electrical energy transmission system also can increase transmission distance with the voltage multiplier receiver connected in the rear of the secondary-side coreless planar transformer. Both the power transmission and circuit operation are explained in this paper. Finally, a prototype system is constructed and the validity has been confirmed with experiment and practical measurements.

The Compensation Research of Contactless Electrical Energy Transmission System

Contactless electrical energy transmission (CEET) system realizes power transmission with no electrical or physical connection by the perfect combination of inductive coupling technique and electronics. This paper studies the characteristics of the CEET system based on the loosely coupled transformer mathematical model, then analyses the power transmission performance and its changing rules in different compensation topologies. We can get the parameter requirements when the load obtains the maximum transmission power from these studies. This work can provide reference to optimize the circuit design and promote the power transmission ability for the CEET system.

A Study of Contactless Energy Transmission for an Implantable Medical Device

It is necessary for patients with implanted medical devices to have surgery in order to change devices whose battery cells have run out. We have suggested changing the battery into a secondary rechargeable one with contactless energy transmission, but it has been difficult to transmit electrical energy without increasing the eddy loss caused by the metal case of the device. We designed a rechargeable cardiac pacemaker with contactless electrical energy transmission and confirmed that it has a secondary power transmission efficiency of 26-40% at 0.4 W. However, an implantable cardioverter defibrillator (ICD) needs a larger volumetric battery than a cardiac pacemaker. It is necessary to transmit a large amount of power without increasing the eddy current loss, and it is important to estimate the eddy loss caused by the metal case.

A highly efficient contactless electrical energy transmission system

AbstractThis paper proposes a new concept for contactless electrical energy transmission system for an elevator and an automated guided vehicle. The system has rechargeable batteries on the car and electrical energy is supplied at a specific place. When electric power is supplied to the car, it runs automatically and approaches the battery charger. Therefore, a comparatively large gap is needed between the primary transformer at the battery charger and the secondary transformer on the car in order to prevent damage which would be caused by a collision. In this case, a drop of the transformer coupling rate due to the large gap must be prevented. In conventional contactless electrical energy transmission technology, since electric power is received by a pickup coil from a power line, a large‐sized transformer is required. When the distance over which the car runs is long, the copper loss of the line also increases. The developed system adopts a high‐frequency inverter using a soft switching method to miniaturize the transformer. The system has a coupling rate of 0.88 for a transformer gap length of 10 mm and can operate at 91% efficiency. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(1): 66–74, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10290

A contactless electrical energy transmission system for portable-telephone battery chargers

A high-performance contactless electrical energy transmission (CEET) technique which employs the inductive energy transmission principle is described. The proposed technique enables the implementation of high-efficiency high-power-density fully regulated CEET systems suitable for applications with a wide input and load range. A high efficiency of the system is achieved by recovering the energy stored in the leakage inductances of the transformer by incorporating them in the operation of the circuit, and by employing high-frequency-inverter and controlled-rectifier topologies that allow a controlled bidirectional power flow through the transformer. In addition, a feedforward variable-switching-frequency control of the inverter is used to maintain approximately constant power transfer through the transformer with the input voltage changes, whereas the output-side rectifier employs a local pulsewidth-modulation control to achieve a tight regulation of the output in the presence of load variations. Specifically, the described CEET system is suitable for use in universal-input battery chargers.

Highly Efficient Contactless Electrical Energy Transmission System.

This paper proposes a new concept for a contactless electrical energy transmission system for an elevator and an automated guided vehicle. The system has rechargeable batteries on the car and electrical energy is supplied at a specific place. When electric power is supplied to the car, it runs automatically and approaches the battery charger. Therefore, a comparatively large gap is needed between the primary transformer at the battery charger and the secondary transformer on the car in order to prevent damage which would be caused by a collision. In this case, a drop of the transformer coupling rate due to the large gap must be prevented. In conventional contactless electrical energy transmission technology, since electric power is received by a pick-up coil from a power line, a large-sized transformer is required. And when the distance over which the car runs is long, the copper loss of the line also increases. The developed system adopts a high frequency inverter using a soft switching method to miniaturize the transformer. The system has a coupling rate of 0.88 for a transformer gap length of 10mm and can operate at 91% efficiency.

1309 テールコードレスエレベータシステムの検討

This paper proposes a new concept for a tail cordless elevator system. The tail cords bring a vibration and a leaning of the elevator car in skyscrapers because tail cords become long and heavy. The proposed system has rechargeable batteries on the car and electrical energy is supplied at specific floors by a contactless electrical energy transmission. This system needs a transformer which has high coupling rate. This paper shows some simulated results and experimental results of the transformer shapes for a tail cordless elevator system. The developed transformer, which has 10 mm gap, has a coupling rate of 0.88 and can supply the power at 91% efficiency.

A contactless electrical energy transmission system

Most mains-operated equipment in use today is connected to the supply via plugs and sockets. These are generally acceptable in benign environments, but can be unsafe or have limited life in the presence of moisture. In explosive atmospheres and in undersea applications, special connectors must be used. This paper describes a technique, the contactless energy transfer system (CETS), by which electrical energy may be transmitted, without electrical connection or physical contact, through nonmagnetic media of low conductivity. The CETS, which has been used to transfer up to 5 kW across a 10 mm gap, employs high-frequency magnetic coupling and enables plug-in power connections to be made in wet or hazardous environmental conditions without the risk of electric shock, short circuiting, or sparking. Energy may be transmitted without the necessity for accurately manufactured "plug-and-socket" mechanisms and may be transmitted from source to load, even when there is relative motion. Load-source voltage matching may be made inherent to the system.