Electromagnetic Transducer Research Articles

Application of Multi-Branch Cauer Circuits in the Analysis of Electromagnetic Transducers Used in Wireless Transfer Power Systems.

In this paper, the feasibility of applying a multi-branch equivalent model employing first- and second-order Cauer circuits for the analysis of electromagnetic transducers used in systems of wireless power transfer is discussed. A method of formulating an equivalent model (EqM) is presented, and an example is shown for a wireless power transfer system (WPTS) consisting of an air transformer with field concentrators. A method is proposed to synthesize the EqM of the considered transducer based on the time-harmonic field model, an optimization algorithm employing the evolution strategy (ES) and the equivalent Cauer circuits. A comparative analysis of the performance of the considered WPTS under high-frequency voltage supply calculated using the proposed EqM and a 3D field model in the time domain using the finite element method (FEM) was carried out. The selected results of the conducted analysis are presented and discussed.

Scaling laws of electromagnetic and piezoelectric seismic vibration energy harvesters built from discrete components

This paper presents a theoretical study on the scaling laws of electromagnetic and piezoelectric seismic vibration energy harvesters, which are assembled from discrete components. The scaling laws are therefore derived for the so called meso-scale range, which is typical of devices built from distinct elements. Isotropic scaling is considered for both harvesters such that the shape of the components and of the whole transducers do not change with scaling. The scaling analyses are restricted to the case of linearly elastic seismic transducers subject to tonal ambient vibrations at their fundamental natural frequency, where the energy harvesting is particularly effective. Both resistive-reactive and resistive optimal electric harvesting loads are considered. The study is based on equivalent formulations for the response and power harvesting of the two transducers, which employ the so called electromagnetic and piezoelectric power transduction factors, Πcm2 and Πpe2. The scaling laws of the transduction coefficients and electrical and mechanical parameters for the two transducers are first provided. A comprehensive comparative scaling analysis is then presented for the harvested power, for the power harvesting efficiency and for the stroke of the two harvesters. Particular attention is dedicated to the scaling laws for the dissipative effects in the two harvesters, that is the Couette air losses and eddy currents losses that develop in the electromagnetic harvester and the material, air and dielectric losses that arise in the piezoelectric harvester. The scaling laws emerged from the study, are thoroughly examined and interpreted with respect to equivalent mechanical effects produced by the harvesting loads.

The choice of the method and technical means for the automatic control of the insulation thickness of the frames in the winding process

The existing problems in the field of controlling the insulation thickness of cylindrical frames in the process of automatic winding are shown. Methods of controlling the insulation thickness of steel and plastic frames used in the electrical industry are also analyzed.Control of the insulation thickness after winding increases the amount of waste thermal insulation from expensive materials (for example, glass insulation), eliminating the identified violations is rather time-consuming and can make products unusable. Therefore, automation of the insulation thickness control process during winding has always been a difficult but urgent task. The solution to this problem can eliminate manual labor, reduce waste and improve the quality of industrial products used in the electrical and radio engineering industries. Operation principles, physical models and applications of various types of electromagnetic transducers of non-electrical quantities to electrical ones are considered. Features and characteristics of the main types of electromagnetic transducers of the insulation thickness of frames are analyzed. The characteristics of the main types of electromagnetic transducers of the thickness of glass insulation of frames are compared, their relative advantages and disadvantages are shown. Based on the analysis of the appropriate methods for controlling the thickness of various elements, problems are identified in the automation of insulation thickness control of plastic and steel frames in the winding process. Comparative analysis of the designs and characteristics of existing transducers shows that it is necessary to improve the design of linear induction levitation-screen suspensions and create effective methods of transmitting displacements to the levitation screen. Then the obtained unconventional designs can be successfully used for automatic control of the insulation thickness during winding it on rotating frames. For this purpose, differential inductive and transformer transducers with levitation screens and moving measuring windings are recommended. These transducers provide the required measurement accuracy, unambiguous continuous conversion of the insulation thickness into an electric signal in the winding process.

LTCC Flow Sensor with RFID Interface.

The idea of battery-less flow sensors and their implementation in wireless measurement systems is presented in this research article. The authors take advantage of their latest achievements in the Low Temperature Co-fired Ceramic (LTCC) technology, RadioFrequency Identification (RFID) technique, and increasing availability of low power electronics in order to get rid of the need to use electrochemical cells in a power supply unit of the elaborated device. To reach this assumption, special care has to be put on the energy balance in such an autonomous sensor node. First of all, the new concept of an electromagnetic LTCC turbine transducer with a signal conditioner which only draws a current of around 15 µA, is proposed for measuring a flow rate of fluids. Next, the autonomy of the device is showed; measured data are gathered in a microcontroller memory and sent to a control unit via an RFID interface which enables both information exchange and power transfer. The energy harvested from the electromagnetic field is used to conduct a data transmission, but also its excess can be accumulated, so the proposed sensor operates as a semi-passive transponder. The total autonomy of the device is achieved by implementing a second harvester that continually gathers energy from the environmental electromagnetic field of common active radio systems (e.g., Global System for Mobile Communications (GSM), wireless network Wi-Fi).

Towards the Analogy of Electrostatic and Electromagnetic Transducers

Electromechanical, or mechatronic, transducers exchange energy between the mechanical and electrical domain via electrostatic and electromagnetic transduction principles, which are the basis for actuators and sensors. This paper reveals the simple analogy between electrostatic and electromagnetic transducers. Summarizing the well-known Gauß, Ampère’s, Ohm’s, Chua’s, Newton’s, Hook’s and the damping laws into a signal-flow diagram with linearized coefficients, the model shows the transducers reciprocity and physical behavior of damped spring-mass mechatronic systems. The presented modeling approach simplifies the derivation of transfer functions, the pull-in phenomenon, and the coupling factors for the design of feedback methods for mechatronic systems. The analogies are shown by comparing an electrostatic and an electromagnetic parallel-plate actuator, represented by a torsional MEMS scanning mirror and a hybrid reluctance fast steering mirror, respectively. The paper discusses the actuators performance and compares the transducer coefficients and the intrinsic stiffness regarding pull-in.

Study of an Ultrasonic Probe Installed into a Small Diameter-Pipe Using an Electromagnetic Acoustic Transducer

Metal pipes having an inner diameter of about 25 mm or less are frequently used as heat exchangers for power plants, gas pipes, and water pipes. However, erosion and corrosion due to long-term use may cause serious accidents, such as steam leaks, resulting in economic loss and environmental pollution. Therefore, inspection of the entire length and thickness before shipping or monitoring during operation are important technologies. However, no inspection technology including the inside of the wall thickness has been developed. The purpose was to develop an ultrasonic probe that can inspect the inner and outer surfaces from the inside of the pipe at the same time. The developed ultrasonic probe is based on an electromagnetic ultrasonic transducer (EMAT) that does not require a couplant and is then easy to install in a pipe. The EMAT for the longitudinal and for the transverse vibration mode guided wave are connected in series in order to take into account the variety of defects. First, the EMAT was successfully developed for each mode. That is, it was conducted by using the magnetostrictive effect for the longitudinal mode type and by using the Lorentz force for the transverse mode type. and evaluated to improve the performance. The reflected signal from a notch defect was then evaluated in the state that each EMAT was connected in series using any artificial defects and found to be able to detect any notches with about 10% depth or about 15% circumferential length.

A study on torsional guided wave EMAT array and its application in embedment depth inspection of guardrail post

It is always a challenge to quickly and effectively inspect the embedment depth of highway guardrail posts. This paper focuses on an electromagnetic ultrasonic transducer (EMAT) array that can excites torsional mode (T-mode) guided waves and applies it to check the embedment depth of guardrail posts. First of all, we presented a torsional guided wave EMAT array that can be used to quickly inspect the embedment depth of guardrail posts. The working principle of the EMAT array was described in detail. Secondly, a torsional guided wave EMAT array composed of 12 racetrack coils and 24 permanent magnets was simulated to verify the excitation and propagation process of torsional guided wave in a post. Then, a method for detecting the embedment depth of a post using the travel time of a torsional guided wave in the post was put forward. Finally, an experimental system was set up to carry out embedment depth detection experiments on posts with different depths buried in soil and concrete. Experiments have verified the feasibility of using the torsional guided wave EMAT array to inspect the embedment depth of the guardrail post.

High Performance Hybrid Piezoelectric-Electromagnetic Energy Harvester for Scavenging Energy From Low-Frequency Vibration Excitation

There are many difficulties in the power supply of the wireless monitoring system for coal mine mechanical equipment. Vibration energy scavenging is a green and effective way to solve this problem considering the intense and continuous vibration of coal mechanical equipment. In this paper, a novel hybrid vibration energy harvester was designed and manufactured, which combined electromagnetic and piezoelectric transduction units. Vibration drives the two units to move in the vertical and horizontal directions to realize the energy conversion. The mathematic model was built to calculate and predict the performance while the simulation on the distribution of magnetic field and piezoelectricity potential provided the details in the design. Besides, the output signal generated by the vibration excitation of the electromagnetic unit, piezoelectric unit and the whole energy harvester were studied simultaneously. Moreover, the resonance frequency was tested to be 14Hz, and the optimum matching impedance was measured to be 1kΩ and 10kΩ with the parallel and series connection of PH and EH, respectively. The maximum output power of the HPEH with the parallel connection pattern can reach 80.10mW at the acceleration of 2g. In the application experiment, the HPEH can facilely light up 120 LEDs and supply stable power for the electronics and sensors.

Optimization and Performance Evaluation of a Transducer for Bone Conduction Implants

We designed and implemented an electromagnetic transducer for implantable bone conduction hearing aids. The proposed transducer is smaller than previous bone conduction transducers for easy implantation and was designed using high permeability metals to produce large electromagnetic forces. In addition, the number of cantilever beams was changed from two to three to minimize distortion of the transducer, potentially due to twisting of the cantilever beam. The proposed transducer consists of a titanium cover with three screw holes, a metal ring, a circular plate, a vibrational membrane with a three-cantilever structure, a metal plate and cylinder, a permanent magnet, top and bottom coils, and a cylindrical titanium case. The transducer was optimally designed based on analysis of electromagnetic and mechanical vibrations, and the target resonance frequency was derived by controlling the variable elements of the vibrational membrane. The transducer was manufactured based on the results of finite element analysis, and the validity of the design was verified by comparing the results of vibration measurement experiments and a simulation. Finally, to evaluate the performance of the proposed transducer, the transducer was attached to the mastoid of participants and functional near-infrared spectroscopy was used to measure brain activation changes of the auditory cortex due to vibration stimulation.

Points Further North: An acoustemological cartography of non-place

This paper discusses Points Further North, a VR documentary that applies an expanded acoustemological framework to the acquisition and dissemination of audio-visual content in order to investigate a non-place that is characteristic of the Anthropocene. The project exploits the possibilities inherent in the amplification of the vibratory and electromagnetic spectra that permeate our urban environments: infrasonic/tactile elements are disseminated via wearable haptic interfaces and the electrical emissions of our technotope are sonified via the via use of electromagnetic transducers. In addition, the project explores the possibility of integrating mnemonic sound propagation as a relevant, affective component of a contingent soundscape.

Dependence of longitudinal magnetic permeability and transverse conductivity on mechanical loads on the shaft

This research deals with transformer type eddy-current transducer connected in differential circuit and it also proposes method for real-time evaluating mechanical tension in metal cylindrical products. The authors have proposed contactless method for estimating product mechanical deformation which is based on utilizing correlation connections between metals’ electromagnetic properties and their structural condition. The authors have introduced a generalized normalized informative magnetic parameter and on its basis obtain basic transform functions aided for determining increments of relative magnetic permeability and specific electric conductivity of product under load comparatively to standard sample. The article shows the possibility of using the differential method to increase the sensitivity of the evaluation of cylindrical products mechanical parameters. The authors have developed a physical model of an electromagnetic transducer with a product that is subjected to torsion, a theoretical justification is given at the level of the domain structure of the material under study and electromagnetic phenomena. The authors have created an experimental setup, the results of experimental studies of the influence of the mechanical moment caused by the torsion of an object on its electromagnetic properties were obtained. The research has proposed amplitude and phase methods for evaluating mechanical stresses. The results of the research allow to conclude, that there is an efficient transducer operating mode in the range 1 ≤ х ≤ 3, in which for η = 0,38 errors of mr and  estimation are less than 1% and 3% correspondingly. It is also noticeable, that in this range of x relative sensitivity of transducer is maximal. This allows us to create industrial devices for contactless multi-parameter evaluation of physical and mechanical parameters of metal products and structures. The obtained results of theoretical and experimental studies do not contradict the previously known laws of theoretical mechanics, which allows them to be widely used in the practice of nondestructive testing.

Dynamics and high-efficiency of a novel multi-stable energy harvesting system

Scavenging energy from external vibration with low-frequencies and low-level intensities has always been a huge challenge for the energy harvesting. To remedy this key issue, this study is to present a novel multi-stable electromagnetic transduction energy harvesting system by adjusting the geometric parameters of linear springs. Here, we prove that the multi-stable energy harvesting system composed of a nonlinear restoring mechanism can significantly improve the efficiency of the energy converter. The electromechanical model is set up, and the corresponding equations are derived by the Extended Averaging Method and Fokker–Planck equation analysis. The response under harmonic excitation exhibits that, compared to a mono-stable and a bi-stable system, with a tri-stable or a quad-stable system, we can achieve a higher-energy interwell motion with large-amplitude periodic oscillation, leading to significant increases of the harvested current and power. Moreover, improved the expected value of the mean square current and mean harvested power can also be attained under the Gaussian white noise with a small intensity. The results show that the proposed multi-stable system is a feasible design that can improve the power capture performance of energy harvesting from low-level excitations.

Synchronized Switch Harvesting on ElectroMagnetic System: a nonlinear technique for hybrid energy harvesting based on active inductance

This paper proposes a hybrid nonlinear interface combining both piezoelectric and electromagnetic effects for energy harvesting purposes. Based on the previously developed Synchronized Switch Harvesting on Inductor (SSHI) scheme, this technique aims at including as much as electroactive parts as possible, thus advantageously replacing the passive inductance in the SSHI approach by an electromagnetic transducer. The proposed scheme, called Synchronized Switch Harvesting on ElectroMagnetic system (SSH-EM) results in a significant increase of the output voltage, thus leading to a consequential increase of the harvested power, especially in the case of low-coupled systems, when compared to the classical SSHI approach and the standard approach (i.e., directly connecting the piezoelectric element to the load through a diode bridge rectifier and a smoothing capacitor). The working principle, along with theoretical developments, and supporting experimental results, are presented, both considering structures featuring constant displacement magnitude or structures driven at their resonance frequency with a constant excitation magnitude.

Electromagnetic excitation technique for nonlinear resonant ultrasound spectroscopy

Nonlinear resonant ultrasound spectroscopy (NRUS) is a method that can be used to determine the amount of microcracking in structures. The nonlinear parameter extracted in NRUS is based on the dependence of the resonance frequency on vibration amplitude in the presence of damage. NRUS measurements typically are excited with a piezoelectric transducer, but here the application of an electromagnetic transducer is explored as an alternative. The electromagnetic transducer, unlike a single piezoelectric, allows selective excitation of longitudinal, torsional, and bending vibrations in a rod-shaped sample. Measurement of the nonlinear properties of the sample for each type of vibration is therefore possible. This electromagnetic technique involves gluing a coil of wire onto the end of a rod sample and placing it in a magnetic field. By controlling which part of the coil is inside the strongest region of the magnetic field, the principal direction of the driven oscillations in the rod can be controlled. Both piezoelectric and electromagnetic excitation techniques are tested by measuring the parameter of nonlinearity for longitudinal motion, αE, in a sample of Berea sandstone. The electromagnetic technique was shown to measure a 30% higher mean value for αE than the piezoelectric technique.

МОДЕЛЬ ПЬЕЗОЭЛЕКТРИЧЕСКОГО ПРЕОБРАЗОВАТЕЛЯ КЛАПАНА ПОДАЧИ ГАЗА В СУДОВОЙ ДИЗЕЛЬ-ГЕНЕРАТОР

The increase of safety requirements and ensuring of the operability of marine dual-fuel diesel engines which are used on gas carriers and utilize evaporating gas from cargo tanks requires the use of devices based on new physical principles. Currently, an electromagnetic transducer – a solenoid, during the operation of which an incomplete opening / closing is observed, leading to frequent failures and methane slip, is used to control the gas admission valve. The aim of the study is to create a model of a piezoelectric actuator based on a stacked column of piezoelectric washers for gas supply valve to a marine diesel generator. Typical block of a model of piezoelectric washer with longitudinal polarization in the SimInTech electronic modeling environment based on PIC255 ferro-rigid ceramics, which allows to obtain maximum displacement, has been developed. The environment of electronic modeling allows in a short time to build a model of a large number of elements of the same type in the structure and, sometimes, with the same type of parameters, which give a gain compared to MathLab Simulink. Compiled piezo-washer models based on PIC255, SP-4, and Pb(ZrxTi1-x)O3-19 piezoceramics are listed in the SimInTech Electronic Modeling Component Palette library in the Actuator group of elements. As a result of modeling a piezoelectric transducer in the form of a stacked column, it has been found that blocks of three and sixty washers satisfy the requirements for the speed of the gas admission valve in marine dual-fuel medium-speed diesel generator. However, to increase the displacement, more than 200 elements are necessary, which leads to an increase in overall dimensions several times greater than the dimensions of the solenoid. An increase in the displacement with the minimum dimensions of the pillars is possible using differential structures, reinforcing elements in the form of rockers and levers. To reduce fluctuations, it is possible to use dynamic property correction methods – sequential correction and correction using flexible and rigid feedbacks, the use of controlled current sources, digital PID controllers and Fuzzy logic.

A Frequency Up-Converted Hybrid Energy Harvester Using Transverse Impact-Driven Piezoelectric Bimorph for Human-Limb Motion.

Energy harvesting from human-body-induced motion is mostly challenging due to the low-frequency, high-amplitude nature of the motion, which makes the use of conventional cantilevered spring-mass oscillators unrealizable. Frequency up-conversion by mechanical impact is an effective way to overcome the challenge. However, direct impact on the transducer element (especially, piezoelectric) increases the risk of damaging it and raises questions on the reliability of the energy harvester. In order to overcome this shortcoming, we proposed a transverse mechanical impact driven frequency up-converted hybrid energy harvester for human-limb motion. It utilizes the integration of both piezoelectric and electromagnetic transducers in a given size that allows more energy to be harvested from a single mechanical motion, which, in turn, further improves the power density. While excited by human-limb motion, a freely-movable non-magnetic sphere exerts transverse impact by periodically sliding over a seismic mass attached to a double-clamped piezoelectric bimorph beam. This allows the beam to vibrate at its resonant frequency and generates power by means of the piezoelectric effect. A magnet attached to the beam also takes part in generating power by inducing voltage in a coil adjacent to it. A mathematical model has been developed and experimentally corroborated. At a periodic limb-motion of 5.2 Hz, maximum 93 µW and 61 µW average powers (overall 8 µW·cm−3 average power density) were generated by the piezoelectric and the electromagnetic transducers, respectively. Moreover, the prototype successfully demonstrated the application of low-power electronics via suitable AC-DC converters.

Theoretical model construction and structure optimization of electromagnetic flow transducer based on neural network

Theoretical model construction and structure optimization of electromagnetic flow transducer based on neural network

Thermal damage assessment of metallic plates using a nonlinear electromagnetic acoustic resonance technique

Low efficiency of energy transition is generally considered to be the only weakness of electromagnetic ultrasonic transducers (EMATs). Electromagnetic acoustic resonance (EMAR) technique has been successfully used to overcome this disadvantage with a combination of the EMATs with the ultrasonic resonant method. In this paper, a nonlinear EMAR technique has been proposed to evaluate the thermal damage of metallic materials, which combines the feature of EMAR with the merit of higher harmonic generation that provides an effective indicator to material damage. The use of contactless EMATs can isolate the material nonlinearity and maintain the coupling condition consistently on measurements of higher harmonics generated. EMAR provides high enough signal magnitude for higher harmonic generated. An experimental scheme is proposed and applied to assess the thermal damage in aluminum and nickel plates. In addition, conventional EMAR techniques based on the measure of shear wave velocity and attenuation within a certain frequency range, are also carried out for the specimens. The experimental results show a monotonic relationship between the normalized amplitude of higher harmonic generated and the artificial thermal loading time, while no stable trends are observed by conventional linear EMAR approaches. The results in this paper indicate that nonlinear EMAR technique proposed can be used to assess the thermal damage in both nonferromagnetic and ferromagnetic materials, with improved reliability and sensitivity over linear one.

Modelling and Verification of Nonlinear Electromechanical Coupling in Micro-Scale Kinetic Electromagnetic Energy Harvesters

Electromechanical coupling in kinetic energy harvesters is the key aspect of these devices that ensures an effective energy conversion process. When modelling and designing such devices, it is necessary to incorporate electromechanical coupling correctly since it will determine the amount of energy that will be converted during its operation. As the engineering community prefers compact (lumped) models of such devices, the conventional choice of the lumped model for the electromagnetic type of electromechanical coupling is linear damping, proportional to the velocity of the mechanical resonator in a harvester, leading to the idea of maximizing the velocity in order to improve the energy conversion process. In this paper, we show that electromechanical coupling in electromagnetic kinetic energy harvesters is inherently nonlinear and requires a number of aspects to be taken into account if one wants to optimize a device. We show that the proposed model, which is based on first principles of electromagnetics, can be reduced to a nonlinear lumped model that is particularly convenient for analysis and design. The modelling approach and the resulting lumped model are verified using two MEMS electromagnetic harvesters operating over a range of frequencies from 300 to 500 Hz (Harvester A) and from 50 to 70 Hz (Harvester B) generating from mV (Harvester A) to few volts (Harvester B) of RMS voltage, respectively. The proposed modelling approach is not limited to energy harvesters but can also be applied to magnetic sensors or other MEMS devices that utilise electromagnetic transduction.

Experimental characterization and performance improvement evaluation of an electromagnetic transducer utilizing a tuned inerter

This research reports on the experimental verification of an enhanced energy conversion device utilizing a tuned inerter called a tuned inertial mass electromagnetic transducer (TIMET). The TIMET consists of a motor, a rotational mass, and a tuning spring. The motor and the rotational mass are connected to a ball screw and the tuning spring interfaced to the ball screw is connected to the vibrating structure. Thus, vibration energy of the structure is absorbed as electrical energy by the motor. Moreover, the amplified inertial mass can be realized by rotating relatively small physical masses. Therefore, by designing the tuning spring stiffness and the inertial mass appropriately, the motor can rotate more effectively due to the resonance effect, leading to more effective energy generation. The authors designed a prototype of the TIMET and conducted tests to validate the effectiveness of the tuned inerter for electromagnetic transducers. Through excitation tests, the property of the hysteresis loops produced by the TIMET is investigated. Then a reliable analytical model is developed employing a curve fitting technique to simulate the behavior of the TIMET and to assess the power generation accurately. In addition, numerical simulation studies on a structure subjected to a seismic loading employing the developed model are conducted to show the advantages of the TIMET over a traditional electromagnetic transducer in both vibration suppression capability and energy harvesting efficiency.