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please read this for more
Contactless Energy Transfer
A Better Solution For A Mobile World
Talk to any plant engineer or production system designer and you ll find that electrical wiring is the bane of their existence. From installing the wires, to rewiring as production lines need to be changed, to repairing damage caused by careless workers, electrical wires represent an ongoing cost and risk for downtime in manufacturing plants.
Until recently, the miles of electrical wiring that snake around any manufacturing facility, hanging down from ceilings and extending across corridors between equipment, have been viewed as a necessary aspect of industrial automation.
But today industry is moving toward a wireless world. Like consumers with their cell phones, laptops and PDA s, industrial companies want wireless technologies that improve versatility, reduce costs and maintain connectivity. One of the latest developments to draw interest among engineering personnel is contactless energy transfer for powering and controlling motors
While wireless communication is now common in factories, wirelessly transferring 16kW of electricity through the air to power equipment is a relatively new phenomenon in the United States.
In a typical automated manufacturing environment, where carts full of parts must be moved between the different stages of a production process, a contactless system transfers electrical energy inductively from an insulated conductor in a fixed installation to one or more mobile loads. Electromagnetic coupling is realized via an air gap, so it is not subject to wear and costly maintenance.
Contactless energy transfer reduces costs in several ways: It eliminates festooning or overhanging utilities. The underground wiring is compact and poses no trip hazards. There is no carriage to run out on the shop floor. There are also no pits to be dug to drop in trailing utilities.
In addition to lower costs, a mobile system using contactless energy transfer provides greater versatility: The contactless system enables more flexible track layout with curves and switches, simple segmentation of tracks, which makes it easy to extend a track or change travel directions, and higher speeds.
Contactless energy transfer is ideal for applications where:
The mobile equipment has to cover long distances
A variable, extendable track layout is required
High speeds have to be achieved
The energy transfer has to be maintenance free
Additional environmental contaminants are not permitted in sensitive areas
The operation takes place in wet and humid areas
Maintenance and ambient conditions are important factors in constructing systems for material handling and transportation applications, such as automotive assembly, storage and retrieval logistics and sorting. Typical applications that could benefit from contactless energy transfer include:
Overhead trolleys
Conveyor trolleys
Guided floor conveyors
Push-skid conveyors
Storage and retrieval units
Pallet transportation systems
Baggage handling
Panel gantries
Elevator equipment
Amusement park rides
Battery charging stations
By replacing a drag-chain system in a conveyor trolley that transports and sorts pallets, for example, contactless energy transfer enables pallets to transverse over longer distances. Complicated holders for drag chains are eliminated, as is downtime for repairing cable breaks and battery charging. Repairs for wear from bending or torsion are also eliminated.
The wear-free power supply in a contactless system has many advantages in designing and maintaining push-skid conveyors used in automotive assembly, for example, or in storage and retrieval units in a high-bay warehouse. Because there is no conductor rail, there is no danger of introducing contaminants from system leakages and no components that are difficult to reach for maintenance. Problems with fitting the platforms into conveyor belts are also eliminated, since there s no need for high mechanical tolerances between the line cable and pick-up.
Perhaps the biggest advantage of a system based on contactless energy transfer is higher system availability because the system is essentially maintenance free. In a manufacturing environment where change is a constant and speed is an imperative, the versatility, flexibility and reliability of contactless energy transfer systems can reduce the wear-and-tear on plant engineers as well as equipment.
About SEW-EURODRIVE
Engineering excellence and customer responsiveness distinguish SEW-EURODRIVE, a leading manufacturer of integrated power transmission and motion control solutions. SEW introduced the world s first gearmotor more than 75 years ago and its systems are known for high performance and rugged reliability in the toughest operating conditions.
SEW-EURODRIVE offers a comprehensive range of electromechanical and electronic drive solutions. The company s modular product designs allow components to be quickly and cost-efficiently assembled in literally millions of different configurations to create a truly customized solution for every customer.
With its global headquarters in Germany and sales of more than 1.5 billion Euros, the privately held company has more than 11,000 employees with a presence in 46 countries worldwide. SEW operates from 12 manufacturing facilities and 63 regional assembly centers located around the world.
U.S. operations include a state-of-the-art manufacturing facility, five regional assembly centers, more than 60 technical sales offices and hundreds of distributors and support specialists. This enables SEW-EURODRIVE to provide local manufacturing, service and support, coast-to-coast and around the world.
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[attachment=6010]
CONTACTLESS ENERGY TRANSFER
Abstract
In this paper a new topology for contactless energy transfer is proposed and tested that can transfer energy to a moving actuator using inductive coupling. The proposed topology provides long-stroke contactless energy transfer capability in a plane and a short-stroke movement of a few millimeters perpendicular to the plane. In addition, it is to lerant to small rotations. The experimental setup consists of a platform with one secondary coil, which is attached to a linear actuator and a 3-phase brushless electromotor. Underneath the platform is an array of primary coils that are each connected to a half-bridge square wave power supply. The energy transfer to the electromotor is measured while the platform is moved over the array of primary coils by the linear actuator. The secondary coil moves with a stroke of 18cm at speeds over 1m/s, while up to 33W power is transferred with 90% efficiency.
INTRODUCTION
Most high-precision machines are positioning stages with Multiple degrees of freedom(DOF), which often consist of cascaded long-and short-stroke linear actuators that are supported by mechanical or air bearings. Usually, the long stroke actuator has micrometer accuracy, while the Submicron accuracy is achieved by the short-stroke actuator. To build a high-precision machine, as much disturbances as possible should be eliminated. Common sources of disturbances are vibrations, Coulomb and viscous friction in bearings, crosstalk of multiple cascaded actuators and cable slabs.
A possibility to increase throughput, while maintaining accuracy is to use parallel processing, i.e. movement and positioning in parallel within section, calibration, assembling, scanning, etc. To meet the design requirements of high accuracy while improving performance, a new design approach is necessary, especially if vacuum operation is considered, which will be required for the next generation no lithography machines. A lot of disturbance sources can be eliminated by integrating the cascaded long-and short-stroke actuator into one actuator system. Since most long-stroke movements are in a plane, this can be done by a contactless planar actuator.
The topology proposed and tested in this paper provides long-stroke contact less energy transfer (CET) in a plane with only small changes in power transfer capability.
CET TOPOLOGY
The design of the primary and secondary coil is optimized to get a coupling that is as constant as possible for a sufficiently large area. This area should be large enough to allow the secondary coil to move from one primary coil to the next one without a large reduction in coupling. If this can be achieved, the power can be transferred by one primary coil that is closest to the secondary coil. When the secondary coil moves out of range the first primary coil is turned off and the next one will be energized. To ensure a smooth energy transfer to the moving load, the position dependence of the coupling should be minimized, while keeping the coupling high enough to get a high-efficiency energy transfer.
A lot of systems use 2D spiral coils for the primary and secondary coil, since the spiral coil geometry allows relatively high coupling (upto60%) and some tolerance form is alignment of the coils. However, to allow the secondary coil to move from one primary coil to the next, the tolerance for misalignments should be increased. In the proposed system this is done by using a 3D geometry for the primary coil. This results in a fairly constant B-field around the primary coil, which accommodates good coupling in a large area. Further more, since the system is supposed to transfer power to a load moving in a plane, it is convenient to use a shape that is symmetrical in 2D for both the primary coil and the secondary coil:
a square for instance. The geometry of the primary and the secondary coils are optimized with FEM using Maxwell 3D10 Optimetrics.
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Contactless Energy Transfer System
[attachment=17291]
INTRODUCTION
Contactless energy transfer is the process in which electrical energy is transferred between primary and secondary coils through inductive coupling, without electrical contact between the coils. The transfer of energy between devices without the use of physical plugs is a fascinating concept to say the least. The potential applications for such a technology are practically endless and can range from the transfer of energy between low power home and office devices to high powered industrial applications. Medical, marine, and other applications where physical electrical contact might be dangerous, impossible or at the very least problematic, are all prospective candidates for the use of contactless energy transfer.
WORKING
In contactless energy transfer, the main method of transferring energy between primary and secondary coils is through induction and magnetic fields. When primary and secondary coils are coupled through air and do not have a core to guide the magnetic field, the magnetic field spreads out through the air without any predominant path. Because of this, not all of the magnetic field produced by the primary coil is coupled with the secondary coil. The stray magnetic field does not contribute to the transfer of energy between the coils and is a waste of energy. It is possible that part of the stray magnetic field could undesirably couple with other electronic circuits in their vicinity. This is very dangerous, since large magnetic fields could induce extra currents into nearby circuits, causing malfunction or even damaging them. Another concern is the safety of humans and other living matter when exposed to these stray magnetic fields. Magnetic field shaping attempts to mold the magnetic field to maximize the coupling between primary and secondary coils and at the same time minimize the stray magnetic field.
CONCLUSION
The effect of a changing coupling between a primary coil and a secondary coil on the contactless energy transfer is studied.
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[attachment=6812]
Contactless Energy Transfer to a Moving Actuator
Jeroen de Boeij, Student Member, IEE, Elena Lomonova, Jorge Duarte Member, IEE and
Andr e Vandenput, Senior Member, IEE
Abstract
In this paper a new topology for contactless energy
transfer is proposed and tested that can transfer energy to a
moving actuator using inductive coupling. The proposed topology
provides long-stroke contactless energy transfer capability in
a plane and a short-stroke movement of a few millimeters
perpendicular to the plane. In addition, it is tolerant to small
rotations. The experimental setup consists of a platform with
one secondary coil, which is attached to a linear actuator and
a 3-phase brushless electromotor. Underneath the platform is
an array of primary coils, that are each connected to a halfbridge
square wave power supply. The energy transfer to the
electromotor is measured while the platform is moved over the
array of primary coils by the linear actuator. The secondary coil
moves with a stroke of 18 cm at speeds over 1 m/s, while up to
33 W power is transferred with 90% efficiency.
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(09-21-2008, 04:14 AM)remshad_m Wrote: 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 maybe transmitted, without electrical connections or physical contact, through non-magnetic media of low conductivity. CETS, which has been used to transfer upto 5KWs across a 10mm 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 a relative motion. Load source voltage matching may be made inherent to the system..
thnx
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(09-21-2008, 04:14 AM)remshad_m Wrote: 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 maybe transmitted, without electrical connections or physical contact, through non-magnetic media of low conductivity. CETS, which has been used to transfer upto 5KWs across a 10mm 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 a relative motion. Load source voltage matching may be made inherent to the system..
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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 maybe transmitted, without electrical connections or physical contact, through non-magnetic media of low conductivity. CETS, which has been used to transfer upto 5KWs across a 10mm 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 a relative motion. Load source voltage matching may be made inherent to the system..
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