Contactless Energy Transmission Research Articles

Contactless Stimulation of Multiple Piezoelectric Devices Using Electric Field

The contactless energy transmission scheme using parallel-plate capacitor like structure has been explored which provides a platform for energization of multiple piezoelectric (piezo) components. In the proposed method, ac electric field lines produced by copper electrodes penetrate to the piezo components that are coaxially aligned and positioned in-between at certain distance away from each electrode. Consequently, the components are strongly excited at a point where the functioning electric field source frequency alike with the mechanical resonant frequency of the piezo components. The maximum output power corresponding to optimum load and resonant frequency acquired from the contactless energized multi piezo devices is better than that of power obtained from contactless energized single piezo component by this parallel-plate capacitor electric field generator. The testing results reveal the practicability of non contact stimulation/excitation of multi piezo components simultaneously through electric field.

Modelling of non-linear losses in an integrated contactless power supply for magnetically levitated elevator systems using discrete circuit elements

Abstract A contactless energy transmission system is essential to supply onboard systems of electromagnetically levitated vehicles without physical contact to the guide rail. One of the possibilities to realise a contactless power supply (CPS) is by integrating the primary actuator into the guide rail of an electromagnetic guiding system (MGS). The secondary actuator is mounted on the elevator car. During the energy transmission, load dependent non-linear losses occur in the guide rail. The additional losses, which are caused by the leakage flux penetrating into the guide rail, cannot be modelled using the classical approach of iron losses in the equivalent circuit of a transformer, which is a constant parallel resistance to the mutual inductance. This paper introduces an approach for modelling the load dependent non-linear losses occurring in the guide rail using additional variable discrete circuit elements

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.

Performance Simulation Analysis of Contactless Excitation Energy Transmission Realized by Loosely Coupled Magnetic Tank Transformer

Energy coupling realized by contactless magnetic tank transformer as new approach of rotator excitation in synchronous machine could replace brushes and slip rings of traditional excitation. For new contactless energy transmission (CET) system, its research about energy-efficiency quality still remains a low level because application and research of CET isn’t comprehensive, especially how to improve transfer power and efficiency isn’t enough. According to characteristics of contactless energy transmission system, mutual inductance model was used to describe the loosely coupled connection between primary and secondary winding. Then, optimum energy-efficiency product was proposed. We can use this indicator to consider efficiency, system cost, reliability and so on based on maximum output power. Mutual inductance coupling parameter would be optimized through this indicator and optimum design of system energy-efficiency characteristic would be realized at minimum cost. Although the input voltage had little increase, simulation research proved that system efficiency had a quit handsome increase based on optimum energy-efficiency product which established mutual inductance coupling parameter. This work is supported by National Natural Science Foundation (51177031).

The Application of Ideal Efficiency Analysis Mode on Contactless Excitation Energy Transmission System

As a brand of new power transfer system, contactless energy transmission system can be used to improve the security, dependability and flexibility of the power system. Contactless energy transmission technology is suitable for some special fields, so it has already been received the great concern of foreign academia and international engineering technological circle. Energy coupling realized by contactless magnetic tank transformer as new approach of rotator excitation in synchronous machine could replace brushes and slip rings of traditional excitation. This system reduces size, weight and cost of excitation system to great extent. First, a suitable model needs to be founded because contactless energy transfer system is different from the switching power supply. We found the mutual inductance model and then gived a detailed discussion on the loosely coupled magnetic tank transformer. In accordance with the condition of the most power transmission we use the harmonic technique to realize compensation and propose series-series topology. In order to obtain the stable system the harmonic frequency of primary zero phase angle and critical load resistance could be determined based on this circuit. Second, the ideal efficiency analysis mode was proposed to simplify efficiency analysis process. In this process, the ideal efficiency determined by load resistance was introduced into the expression of input and output power and made sure of the last efficiency of contactless excitation energy transmission system. Last, when the air gap and input signal frequency have been maintained, we study the impact on the contactless energy transmission efficiency when the input signal waveform and average power changes. We selected the square wave, sine wave and triangular wave as the input signals. It will provide certain reference for the performance analysis of magnetic tank transformer.

Optimized Parameter of Contactless Energy Transmission System Realized by Optimum Energy-Efficiency Product

Energy coupling realized by contactless magnetic tank transformer as new approach of rotator excitation in synchronous machine could replace brushes and slip rings of traditional excitation. For new contactless energy transmission (CET) system, its research about energyefficiency quality still remains a low level because application and research of CET isn’t comprehensive, especially how to improve transfer power and efficiency isn’t enough. According to characteristics of contactless energy transmission system, mutual inductance model was used to describe the loosely coupled connection between primary and secondary winding. Then, optimum energy-efficiency product was proposed. We can use this indicator to consider efficiency, system cost, reliability and so on based on maximum output power. Mutual inductance coupling parameter would be optimized through this indicator and optimum design of system energy-efficiency characteristic would be realized at minimum cost. Although the input voltage had little increase, experiment and simulation research proved that system efficiency had a quit handsome increase based on optimum energy-efficiency product which established mutual inductance coupling parameter. The results of experiment agreed with the results of theory analysis in general and it verified the validity of theory analysis.

Design of a Contactless Power Supply for Magnetically Levitated Elevator Systems Integrated into the Guide Rail

A contactless energy transmission system is essential to supply onboard systems of magnetically levitated vehicles without physical contact to the guide rail. This paper introduces a contactless power supply (CPS) where the primary is integrated into the guide rail of an electromagnetic guiding system (MGS). The secondary is mounted onboard the elevator car. The advantages of this system when compared to existing energy transmission systems are the low requirement of construction space and reduced costs.

Acoustic Energy Transfer: A Review

Acoustic energy transfer (AET) is a relatively new form of contactless energy transmission that uses sound waves to wirelessly convey energy. In contrast to inductive coupling, it is suited for energy transmission over distances that are large in comparison to the transmitter and receiver dimensions. The frequencies that are used are low, minimizing losses and keeping the electronics simple. This review summarizes the work done on AET by various researchers.

Combination of a contactless power supply with an electromagnetic guiding for a vertical transportation system

A contactless energy transmission system is essential to supply on-board systems of magnetic levitated vehicles without physical contact to a guiding rail e.g. in clean room environment. This paper introduces a combined contactless power supply (CPS) and electromagnetic guiding system (MGS). The actuator of the linear guiding system is part of an inductive energy transmission. With this approach two devices are integrated in one entity. The hybrid actuator consists of an omega shape iron yoke with permanent magnets and coils on its lateral arms. A concentrated primary winding is added to the elevator shaft and a secondary winding is wound on the central arm. Hereby a superposition of the MGS flux and the CPS flux emerges in the magnetic circuit of the actuator. A decoupling of the two systems is achieved by the high frequency of the CPS flux compared to the MGS flux. The proposed system requires less construction space and weight compared to existing energy transmission systems.

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.

Development of New Conveyer Directly Driven by Contact-less Energy Transmission System

This paper focuses on development of new conveyer directly driven by the contact-less energy transmission system. The effect of the resonant circuit and the flux linkage characteristics caused from that are analyzed by using 3D finite element analysis. From the result it is shown that the resonant circuit needs to transfer energy from the primary core to the secondary core. Also the influence of the linear induction motor on the contact-less energy tansmission system is presented. New conveyer and the experimenta1 apparatus was manufactured by using the contact-less energy transmission system and the linear induction motor. Possibility of realization of the conveyer is proved by comparison the simulation result which is obtained by using 2D finite element analysis with experimenta1 one and the characteristic of the voltage and resonant current.

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.

Contactless energy transmission system for linear servo motor

This paper proposes the calculation method of magnetic coupling coefficient of the contact-less energy transmission system for the linear servo motor by the three-dimensional finite element method with a variation of the secondary core positions. The primary, secondary self and leakage inductances, and the capacitances of a resonant circuit are calculated by the finite element analysis results. From these values, the magnetic coupling coefficients are obtained. The secondary voltages and currents at the secondary core positions are calculated by using the resonant circuit and compared.

Consideration of contactless power station with selective excitation to moving robot

A new method of contactless energy transmission to a moving machine is proposed. This system is useful for application with moving robots, including electric vehicles such as an electric wheelchair, an automatic guided vehicle, and so on. A moving robot was used as a model experimental system with these loads. The primary coils, an arrangement of spiral coils used with the selective excitation system, are located on the floor. A secondary spiral coil is attached to the bottom of the robot. The robot receives the magnetic flux radiating from the primary coils, which serves as the power source for the robot. In terms of electric power, in this experimental system the robot needs at least 2 W to start moving. As the robot moves, the excitation follows its movement. We have studied the characteristics of power transmission when the robot moves from one primary coil to another. This selective excitation system was found to be very effective for the overall efficiency of electric power transmission. We also examined the efficiency of the coil system used herein. Based on a comparison of the closed magnetic loop circuit and the open magnetic loop circuit, the efficiency of the former determined to be 70 [%] and that of the latter was determined to be 9 [%]. A monitoring system was constructed to ascertain which coil was excited. Based on our results, it would be possible to apply this contactless power transmission system to larger systems.

Modeling and test of contactless inductive energy transmission

More and more applications require contactless energy transmission: machine tools (rotating table, x–y tables), robotics, electric vehicle loading systems, high speed transportation, a.s.o. The electromagnetic inductive technique is a good solution in a wide range of power. The aim of this paper is to assess solutions for electric vehicles and rotating systems. This way, ironcore rotative transformer and ironless linear transformer are considered. The specific methodology and equations to design such transformers will be presented. A parametric analysis will show the main limits and finally, some design results will also be presented for a high speed underground transportation system – the Swissmetro project.

Method for Stable Energy Transmission to Moving Loads

A new method of contactless energy transmission to moving loads such as electric vehicles (EVs) is proposed. Employing rectangular and spiral coils for the primary and secondary windings in our cordless power station (CLPS), we transmitted over 200 W of energy to an EV motor. The rectangular coil was used for stable transmission in the event of coil misalignment, and the spiral coil for efficient reception of flux from the primary coils. By placing many rectangular coils with their longer sides aligned with the EVs direction of motion, we caused that the energy transmitted was more or less stable with respect to displacement of the EV. A switched excitation system that we added to the primary coils enhanced the total transmission efficiency. A noteworthy feature of the system is that it is controlled by human intention. Only one coil is excited, to the one nearest to the load, to improve the overall efficiency.

Contactless energy transmission to mobile loads by CLPS-test driving of an EV with starter batteries

Starting and driving methods of contactless power transmission to electric vehicles are proposed. By employing rectangular and spiral coils for primary and secondary windings, respectively, for a contactless power station (CLPS), over 200 W of electric power was transmitted to the authors' fabricated EV motor setup and verified its actual operation on it. The EV is a compact prototype driven by CLPS, loaded with a lightweight battery. The battery supplies a part of transient current arising from starting and acceleration of EV. The CLPS-powered prototype could actually be driven at 30 km/h for an overall energy consumption of 100 W. Driving tests with and without CLPS using a 10-mode driving schedule were executed and compared.

Stable energy transmission to moving loads utilizing new CLPS

A new method of contactless energy transmission to such moving loads as electric vehicles (EVs) is proposed in this paper. By employing rectangular and spiral coils for primary and secondary windings in our cordless power station (CLPS), we could transmit over 200 W of energy to our fabricated EV motor set-up and confirmed the actual operation of it. The rectangular coil is for stable transmission against coil misalignment and the spiral coil is for efficient receiving of flux from the primary coil. By placing many rectangular coils with their longer sides along in line with the EV's moving direction, the transmitted energy was more or less stable against the EV's displacement. Furthermore, a switched excitation system on the primary coils enhanced the total transmission efficiency. A switched excitation system is our new structure and it allows only one coil excited which is the nearest to the load among other coils for the sake of the overall efficiency improvement. Using the rectangular spiral-coils and the switched excitation system, we could actually drive our fabricated EV motor set-up of the nominal output 200 W.

Contactless charging and communication for electric vehicles

Charging batteries in electric vehicles needs to cover several aspects including electrical safety, the weight of an onboard charger, different types of chargers needed by different types of batteries, low line disturbance with high efficiency, and the influence of the charging process on the lifetime of the battery. Another important problem is the communication between the vehicle and the outside world during the charging process. This article describes a system combining energy transfer and signal transmission in one unit, which is able to solve all of the above-mentioned problems. Minimal power electronic components are installed in the vehicle. The system uses contactless energy transmission employing an inductive high-frequency coupler. The charging process is monitored and controlled by an onboard charge meter, which can communicate with the converter outside the vehicle via the signal transmission included in the inductive coupler. A laboratory setup able to transfer up to 5 kW was built to demonstrate the performance of the system. The efficiency of the overall system, including all filters, converters, and rectifiers, is at a power level of 5 kW better than 92%. The used gelled lead acid battery, 35 Ah and 288 V, was made from 24 battery modules.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A new approach to synchronize a bidirectional DC‐to‐DC converter for contacfless power supplies

AbstractAfter a short introduction into the field of contactless energy transmission this paper describes a new method to synchronize a bidirectional DC‐to‐DC converter. For example a contactless inductive transmission of energy for robots is introduced. The employed bidirectional DC‐to‐DC converters are used to feed a rotatable transformer. To allow regenerative braking of the robot drives a bidirectional power flow is necessary. Therefore the DC‐to‐DC converter, consisting of two full bridge inverters, has to be clocked synchronously. With the new method only one transformer is needed for bidirectional power flow without any auxiliary components for signal transmission.