Contactless Transformer Research Articles

A design method of high-compatibility horn for broad-bandwidth transducer.

Broad-bandwidth transducers are one of the main areas of focus for the development of power ultrasonic systems, which address the issues that the contactless transformer system cannot track transducer frequency and narrowband transducers are not compatible with different tools. This paper aims to investigate the potential capabilities of broad-bandwidth transducers in terms of compatibility with different horns and to propose a design method for highly compatible tools. The frequency equation of horn is nondimensionalized to calculate relative frequency errors δ. The effects of shape, dimensionless size, and order number on δ are investigated based on the equation. A compatibility range is proposed, and the relationship between it and the required relative bandwidth of the transducer is investigated. Various horns were designed, and the corresponding simulations, impedance measurements, and resonance experiments were conducted to explore the effects of these factors on δ, amplitude, and the quality factor Q. These experiments also verified the feasibility of using a broad-bandwidth transducer that is compatible with different tools. Finally, the application scenarios of the three horns are summarized based on a comparison of their matching ability, amplitude, operational stability, and compatibility range.

Parameter sensitivity analysis and efficiency optimization design of wireless charging system

Electric vehicle (EV) wireless charging technology has recently attracted a lot of attention and has a broad potential for commercial application development. A fundamental performance indicator of wireless charging systems is efficient transmission. Magnetic coupling mechanism design and circuit parameters have the greatest effects on the transmission efficiency of the system. In this study, the output power and efficiency of the wireless power transfer (WPT) circuit were theoretically computed based on the LCC-type resonant network. Simulation studies demonstrate that the transmission efficiency and output gain deviate significantly from the expected value when circuit parameters are changed. To improve transmission efficiency, the optimal impedance configuration was created using a semi-controlled rectifier circuit. Based on electromagnetic field theory and equivalent magnetic circuit model, a new contactless transformer structure was optimized and created, and the new contactless transformer had a higher coupling coefficient. The coil offset had a greater impact on the transmission efficiency. The results indicate that within a certain distance, the coupling coil offset had no impact on transmission efficiency, and beyond that distance, the transmission efficiency was almost non-existent. Both the feasibility of the practical verification and the accuracy of the theoretical study were tested using a low-power wireless charging experimental setup. This paper provides design guidelines for wireless charging systems using circuit parameter sensitivity analysis and contactless transformer optimization design.

Model of Electro-Pulse Processing of Metals Melts

Questions of influence of nanosecond electromagnetic impulses on melts of metals are considered in the article. The analysis of action of impulses on electromagnetic hashing and thermal conditions of a melt showed their small influence. Mechanical (acoustic) action is chosen as the main one. Formulas and values for coefficients of transformation of electromagnetic field to the acoustic one for a number of metals are given. The transformation model in the form of the wave of current running on the radiator is offered. Comparison of action of electromagnetic impulses on melts showed that emergence of acoustic vibrations is the main thing. The theory of contactless transformation of electromagnetic waves in acoustic ones is considered. Comparison with experiments is given. The model of contact electro-pulse processing of metal melts in the form of transition of an electromagnetic wave to acoustic is offered. Acoustic waves change structure of a melt, condition of a crystallization of a melt and improve properties of the hardened metal.

A Novel Flux-Switching Magnetic Gear for High-Speed Motor Drive System

Magnetic gears realize the characteristics such as low acoustic noise and low vibration, maintenance-free by contact-less power transformation. However, conventional magnetic gears are not suitable for high-speed motor drive systems because of their low mechanical strength, which results from the permanent magnets of the input rotor. This article proposes a novel flux-switching magnetic gear for high-speed motor drive systems. The input rotor of the flux-switching magnetic gear consists of an iron core. Therefore, the structure is highly robust and can be driven in the high-speed region. Moreover, the flux-switching magnetic gears offer a high torque density by utilizing stationary field magnets arranged between the pole pieces. Through simulations and the experiments, parameters such as the torque density, mechanical strength, losses, and efficiency of the proposed gear are evaluated.

Modeling and Analysis of Contactless Transformer based on Magnetic Flux Simulation Techniques

Modeling and Analysis of Contactless Transformer based on Magnetic Flux Simulation Techniques

Comparison of Coupling Coefficient and Magnetic Field Distribution of Contactless Transformer

The direct – switched apparatus in use nowadays are connected to the mains through plugs and sockets. These are generally agreed in natural environment, but can be prohibited or have limited life in the presence of moisture, in explosive atmospheres and inside sea applications. So contactless power transmission through a large air-gap is becoming more suitable for the above applications. This paper discusses the effects of geometrical arrangements of contactless transformer for two core types, U-U type and E-E type by means of flux simulation based on finite element method with ANSYS program v 5.4 . It is found that the U-U type core can give higher coupling coefficient within the same core geometry and lower leakages. It could be concluded that the dimensions of the core and the air-gap length determine the transmission behavior.

Comparison of Coupling Coefficient and Magnetic Field Distribution of Contactless Transformer

Comparison of Coupling Coefficient and Magnetic Field Distribution of Contactless Transformer

Study of Contactless Power Supply for Spindle Ultrasonic Vibrator

In this study, a contactless power supply for the ultrasonic motor on the spindle is proposed. The proposed power supply is composed of a series-parallel resonant circuit and a cylindrical contactless transformer. Based on the study and rotation experiments, it can be seen that the proposed power supply can both provide a stable ac power with 25 kHz / 70 V to the ultrasonic motor. When the output power is 250 W, the efficiency of the proposed supply is 89.8 % in respectively rotation tests. When the output power is more than 150 W, the efficiency of the proposed supply is higher than 80 % within the rated output power range.

Misalignment controller in wireless battery charger for electric vehicle based on MPPT method and metaheuristic algorithm

This paper focuses on applying a wireless power transfer WPT technology in an electric vehicle battery charger. The wireless charger system is based on the principle of resonance inductive coupling power through a coreless transformer. The WPT system is considered as a multi parameter and multi constrained nonlinear system. The main contribution in this paper is the use of PSO and GA metaheuristic algorithms in the optimization of a transformer design regarding the impact of a lateral misalignment and the separation distance between the primary and secondary coils. To find the best global solution which is considered as the maximum efficiency in the complex system, both algorithms are compared. A perturbation-and-observation-based tracking system is developed through an efficiency sensing system to act on the misalignment issue and the car position. An additional PSO controller is performed to control the duty cycle of the boost converter in order to follows the maximum efficiency operating points of a WPT system. The discrepancy is the use of the resonant inductive coupling as a source of the MPPT so as to perturb the car position and observe the transferred. Furthermore, the modeling of a contactless transformer is optimized using metaheuristic algorithm.

大容量非接触給電トランスの設計を目的とした高周波変動磁束による損失・温度に関する検討

大容量非接触給電トランスの設計を目的とした高周波変動磁束による損失・温度に関する検討

Optimization of contactless transformer coupling transmission system by Taguchi method

ABSTRACTA contactless transformer coupling (CTC) transmission system transmits electric energy via an alternating magnetic field through an air-gap. The transmitted power can be enhanced by the application of resonant effects. Transmitting and receiving coils are usually single layer solenoids with series capacitors, which, in combination, allow the receiving element to be tuned to the required transmitter frequency. An input DC source is used to obtain high-frequency AC signal through the standardized half-bridge DC/AC switching circuit. Further, the high-frequency signal passes through matching transformer and contactless coupling induction coil, which can be considered as an isolated input and output stage. Coupling must be tight to achieve high efficiency. This paper then applies the methods of Taguchi parameter design forthe contactless transformer coupling transmission system, which enhances the output voltage, loss factor, and output efficiency of the transmission system. The results of measurement verify the feasibility of this structure in the experiment.

Property study of power transmission system for rotary ultrasonic application

Rotary ultrasonic applications are being widely used in machining hard and brittle materials. Conventional conducting ring used as power transmission part limits the ultrasonic applications from rotating at high speed. A high efficiency power transmission system is defined in this article to solve this problem. It consists of a contactless transformer, which was made up of two hollow copper coils, ultrasonic power supply and compensation capacitors. Four compensation methods are proposed and their properties are analyzed through simulations and experiments. The simulations show that S-S compensation is superior to others on the performance of transient and steady circuit parameters and the max transmit efficiency can reach about 97.2% when appropriate compensation method and capacitance are used. Rotary experiments show that speed has little effect on the property of the system.

Processing of Bulk MgB<sub>2</sub> Superconductors for Application in Fault Current Limiters

Fault current limiters (FCL) require superconducting (SC) materials which can provide a definite rate of response to a fault event resulting in the SC – normal state reversible transition. The main characteristics determined the material suitability are the critical current density, jc, thermal conductivity and capacity which are strongly determined by manufacturing technology, in particular, of MgB2. In the paper we estimate the jc of bulk MgB2 samples by the vibrating magnetometer and inductive, contactless transformer, method using ring samples. The bulk MgB2 samples were produced under 30 MPa (hot pressing) and 2 GPa (quasihydrostatic pressing) at 800-1050 оС from different initial ingredients (Mg and B or MgB2 with and without additions). It is shown that the technology process and initial ingredients strongly influence the distribution of boron-and oxygen-enriched nanosized inhomogenities in MgB2 matrix, connectivity between SC grains, material porosity and, as result, the SC properties. The transformer method gives the jc in the range from 1.6·104 up to 6.3·104 A/cm2 at about 4 K while using magnetometer measurements the jc is estimated from 2.24·105 up to 5.1·105 A/cm2 at 10 K in self-magnetic fields. The contradictions in the jc estimated by different methods can be explained by instability of the SC state of MgB2, caused by variation of the applied magnetic field. Using the transformer method AC losses per a cycle before quenching for the best materials were estimated around 0.75-1 J/cm3, while the power of losses was about 200 W. The FCL model with rings cut out from SC MgB2 materials prepared using various technologies demonstrated that MgB2 is a promising material for application in inductive FCLs.

Development of a Cascaded Half-bridge Converter with Contactless Transformer in DC Microgrid

A high efficiency cascaded half-bridge converter for contactless transformer with 1 A, 5V and 600kHz for mobile phone charger application is implemented in this paper by using simple PI discrete algorithm controller. The proposed target is to achieve the arch free, controllable voltage and galvanic isolation outlet and plug power transforming converter in a dc low voltage household power distribution. For the optimized outcome, the parameters are calculated and verified by MATLAB/Simulink program for bench testing. Additionally, this paper will be presented in both of the simulation and implementation results.

Wide-Air-Gap Transformer Model for the Design-Oriented Analysis of Contactless Power Converters

A wireless power converter topology with a small size and a high conversion efficiency has an increasing demand on small-power applications. Some design techniques to transmit power by customized cores have been already developed. However, when transferring energy by wide-gap transformers employing small-sized commercialized cores, the power losses on the winding greatly increase as the frequency increases. Then, the efficiency of the contactless power system decreases significantly due to the conduction loss and reactive components in the resonant circuit. Even though series-parallel resonant converters are largely employed, which can provide an infinite shunt impedance regardless of the coupling coefficient, when a commercialized core is employed for loosely coupled contactless power transfer applications, the large leakage inductance of the transformer significantly influences the additional power dissipation on the transformer windings. In this paper, an operating principle on how the contactless transformer with commercialized core contributes to the low efficiency is discussed. Also, a new frequency-dependent R- L ladder circuit model is introduced for the design-oriented analysis of wide-air-gap contactless power converters including the frequency-dependent losses of the transformer. A new design procedure with the proposed model is suitable for the contactless transformers employing commercialized cores. The proposed design approach is validated by 98.8-W hardware experiments. Finally, the simulation waveforms and the hardware results are compared to verify the accuracy of the frequency-dependent transformer model.

二層構造三相非接触トランスの提案と検討

二層構造三相非接触トランスの提案と検討

T字形等価回路モデルを利用した鉄道用電磁誘導式非接触給電装置のコア形状・位置ずれによる特性変化の研究

T字形等価回路モデルを利用した鉄道用電磁誘導式非接触給電装置のコア形状・位置ずれによる特性変化の研究

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).

Finite Element Analysis of a Contactless Power Transformer with Metamaterial

Wireless power transfer technologies enable power transfer to loads through air. The contactless power transformer is a key element of it. In this work, a new transformer with metamaterial is proposed, through which the power transfer distance increases. The electromagnetic properties about metamaterial are discussed at first. Then, the finite element analyses of this transformer are presented as well. The magnetic field distributions and the computational results show that this type of transformer can enlarge the power transfer range of a wireless power transfer system. DOI : http://dx.doi.org/10.11591/telkomnika.v12i1.3221

Finite Element Analysis of a Contactless Transformer

Inductively coupling power transfer is an emerging technique, which enables power transfer to loads through air. The contactless transformer is the key component of it, and the design of a transformer is a time-consuming work with a large number of tests. In this paper, a design method of contactless transformer with finite element analysis is presented. First the contactless transformer model is deduced from Maxwell Equations, and the self inductance and mutual inductance computational equations are given as well. Then the magnetic field distributions of contactless transformer with different air gaps are presented by simulation of MAXWELL ANSOFT. Furthermore, the skin and proximity effects are analyzed as well. At last, the results are compared with the experimental results with the same dimension and material. The analyses show that there has a good agreement with each other. So by this method, the design period of a contactless transformer will be shorter than before