Electromagnetic Shunt Research Articles

シャント制振のための電磁アクチュエータのセンサレスパラメータ推定

Electromagnetic shunt damping is a sensor-less passive damping technique using an electromagnetic actuator. The accurate values of the parameters of the system are essentially required for designing a controller in the damping technique. This paper proposes a parameter estimation method of an electromagnetic actuator attached to a mechanical structure in order to use for electromagnetic shunt damping. The electromagnetic actuator attached to the structure is modeled as the system including the mechanical and electrical systems which are connected by the electromechanical coupling coefficient. This paper points out a remark on the estimation: The frequency response of the electrical admittance especially neighborhood the natural frequency of the mechanical structure shows an electro-mechanically resonant feature, which does not appear in the pure electrical system without the electromechanical coupling. By applying least squares method to the frequency response data of the electrical admittance neighborhood the natural frequency, the parameters of the mechanical system and the electromechanical coupling coefficient as well as the electrical parameters can be estimated. The proposed estimation method requires only measurements of the frequency response of the electrical admittance across the terminals of the electromagnetic actuator. Therefore, both the parameter estimation and the electromagnetic shunt damping are possible to perform without any displacement or velocity sensors, or any additional actuators. In order to verify the effectiveness of the proposed method, the experiments of parameter estimation and of electromagnetic shunt damping are performed. The experimental results show that the proposed method is effective to estimate the parameters of the electromagnetic actuator without use of any other sensors.

Structural multimode vibration absorbing with electromagnetic shunt damping

This paper presents multimode vibration absorbing methods which employ negative resistance (NR) and negative inductance negative resistance (NINR) electromagnetic shunt damping vibration absorbers. The NR and NINR shunts can change the impedance of an electromagnet so as to change the control force of the absorber. The governing equation of the coupling system is established. What is more, some numerical simulations are carried out and the results show that the absorbers with NR or NINR shunt can effectively suppress the multimode vibration. Furthermore, the root locus is analyzed to design the resistance of a shunt.

Vibration suppression of structure with electromagnetic shunt damping absorber

Vibration suppression of structure with electromagnetic shunt damping absorber

Investigation of negative resistance shunt damping for the vibration control of a plate

In this study, vibration isolation of a plate is investigated by using an electromagnetic shunt damping vibration isolator. The isolator consists of a box-shaped spring, a permanent magnet, an electromagnet, and a shunt circuit. The two ends of the electromagnet connect the negative resistance shunt impedance to constitute a circuit. In principle, the negative resistance shunt impedance could improve the damping force by canceling the inherent resistance of the electromagnet. The governing equation of the plate is established according to Hamilton's principle and Galerkin's method. The numerical simulation is conducted and the result demonstrates that the isolator with the negative resistance shunt circuit is able to dampen the vibration of the plate. What's more, an interesting phenomenon is that the negative resistance shunt influences the natural frequencies of the coupling system.

Dynamic analogy between an electromagnetic shunt damper and a tuned mass damper

An electromagnetic shunt damper (EMSD) is composed of an electromagnetic damper connected to one or more RLC shunt circuits. Through a theoretical comparison, this paper reveals the similarity and difference between an EMSD and a tuned mass damper (TMD), both of which are resonant-type vibration absorbers. The equivalent mass, stiffness and damping coefficient of the EMSD are derived based on the transfer functions of structures with a TMD or an EMSD, and the functions of circuit capacitance and inductance are discussed accordingly. The optimal parameters of the RLC circuit in the EMSD are obtained through H∞ optimization. Despite their different optimal parameters, the EMSD and TMD exhibit comparable control performance with the same equivalent mass ratio. The dynamic analogy between these two types of dampers offers a new perspective for understanding novel EMSDs, given that TMDs have previously been extensively studied. The potentials and constraints of the EMSD are further discussed through numerical case studies in which EMSD control performance is examined in different situations.

Vibration isolation of a beam via negative resistance electromagnetic shunt dampers

In this study, two novel electromagnetic shunt damping vibration isolators (EMSD-VIs) were developed for the vibration isolation of a beam structure. The proposed isolator utilizes a pair of electromagnetic coils and permanent magnet and a box-shaped spring to generate both variable damping and spring effect. The governing equation of the EMSD-VI-supported beam was established according to Galerkin method. The negative resistance was proposed to improve the performance of the isolator. The stability analysis was investigated to determine the design rules of the shunted negative resistance. The acceleration transmissibility of the beam system was simulated by using passive EMSD-VI control and negative resistance (NR)-EMSD-VI control. The experiment was conducted to verify the theoretical model and the numerical simulation. The experimental results demonstrated that the proposed NR-EMSD-VI is capable of isolating the first-order and the third-order vibrations. Also, a discussion of the resonance frequency shift toward higher value was given.

A novel multimode negative inductance negative resistance shunted electromagnetic damping and its application on a cantilever plate

Based on the characteristic of the electromagnetic damping, a novel multimode vibration control treatment, negative inductance negative resistance electromagnetic shunt damping (NINR-EMSD), is proposed and employed to control multimode vibration of a cantilever plate. The negative inductance of the shunt impedance can cancel the inherent inductance of the electromagnet, and the impedance of circuit consisted of the coils and shunt will be a pure resistance and the shunt current will be frequency independent when the inductance of the shunt and the electromagnet are equal with each other. The negative resistance cancels the resistance of electromagnet, and as a result the resistance and the current of the closed circuit will change, which make it feasible to control the multimode vibration of the system. Electromechanical coupling coefficient is obtained based on the equivalent current method. The governing equation of the plate with the electromagnetic shunt damping (EMSD) is established according to Hamilton's principle. Multimode vibration control of the system is simulated and experiments are carried out to verify the performance of the NINR-EMSD. The numerical predictions and experimental results agree well with each other and show that: the negative inductance negative resistance (NINR) of the shunt impedance can increase the damping of the structure notably; the decrease of the resistance of shunt impedance have a significant contribution to the improvement of vibration control performance; the first four modes vibration of the plate can be suppressed simultaneously with the NINR-EMSD.

Design and test of a novel isolator with negative resistance electromagnetic shunt damping

This paper proposes a negative resistance electromagnetic shunt damping vibration isolator and investigates the effectiveness of the isolator. The isolator consists of a shunt circuit and a pair of electromagnet and permanent magnets that are pasted onto a box-shaped spring. A kind of negative resistance shunt impedance is proposed to cancel the inherent resistance of the electromagnet. The electromechanical coupling coefficient and the electromagnetic damping force calculation formula are obtained by Biot–Savart’s law and Ampère’s law, respectively. A single degree of freedom system is employed to verify the performance of the proposed isolator. The governing equation is established. The performance of the proposed isolator under a half-cycle sine pulse is investigated and discussed. Experiments were carried out and the results agreed well with the numerical predictions. Both the results demonstrate that the negative resistance electromagnetic shunt damping vibration isolator could suppress vibration transmitted to the structure effectively.

Electro-Magnetic Shunt Damping with a Digital Virtual Impedance Circuit

Electro-magnetic actuators have potentials of sensor-less vibration control due to the abilities of simultaneous actuation and sensing. This paper discusses a method of the electro-magnetic shunt damping with a digital virtual impedance circuit realizing a resistor or a resistor-capacitor circuit optimally designed by a theory of tuned mass damper. The digital virtual impedance circuit, which consists of a controlled voltage source and a computer, can realize arbitrary impedance. Using the virtual impedance concept, the optimally tuned resistive component which might have negative value can be realized, even though the conventional passive electro-magnetic shunt damping technique suffers from performance degradation due to the inherent resistance of the coli. The experimental results demonstrate the effectiveness of the proposed method. From the analysis of the open-loop transfer function, we also discuss the stability margin of the system and the suitability of the virtual impedance applied to the electro-magnetic shunt.

108 ディジタル仮想インピーダンス回路を用いた電磁シャントダンパ

Because electro-magnetic actuators have both functionalities of actuation and sensing, they have potentials of sensorless vibration control as piezoelectric elements do. This paper discusses an implementation of a digital virtual impedance circuit with a R or RC circuit optimally designed by a theory of passive dynamic damper. The digital virtual impedance circuit, which consists of a computer and a controlled voltage source, can realize an arbitrary impedance. Using the virtual impedance concept, the optimally designed resistive component which might have negative value can be realized, even though conventional electro-magnetic shunt damping suffers from performance degradation.The experimental results demonstrate the effectiveness of the method.

Damper based on electromagnetic shunt damping method

This paper investigates vibration control via electromagnetic shunt damping. A new damper based on electromagnetic shunt damping is designed, and mathematical model of the damper is developed to obtain the equivalent damping coefficien t. Simulation of the vibration control of a SDOF system is conducted. Results of the simulation reveal that the new electromagnetic shunt damper can greatly attenuate vibration transmitted to structures.

Vibration Control Using Shunted Electromagnetic Transducer

This paper describes vibration suppression of the flexible cantilever beams using shunted electromagnetic transducer. The proposed system consists of a coil attached on a cantilever and a permanent magnet placed under the bottom of the coil, and both ends of the coil were connected to the parallel resonant RLC shunt circuit. The dynamic model of cantilever beam with shunted electromagnetic damper was theoretically formulated and used to compare the analytic predictions with the experimental results. The vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper were investigated by tuning the circuit parameters. Also, the effect of the magnetic intensity on the shunt damping was studied with the variation of the gap between the aluminum beam and the permanent magnet. Presented results show that the electromagnet shunt damper has good vibration reduction effect, and it can be successfully applied to reduce the vibration of the flexible structures.

A current-flowing electromagnetic shunt damper for multi-mode vibration control ofcantilever beams

In this paper, a multi-mode electromagnetic shunt damper employing the current-flowingmethod is newly developed for the semi-active vibration control of flexible structures. Theelectromagnetic shunt damper, which is used for the electromagneto-mechanical couplingtransduction between vibrating structures and the electrical shunt circuit, consists of a coiland a permanent magnet. The conducting coil is attached to the cantilever beams and thetwo ends of the coil are connected to the current-flowing shunt circuit for the reductionof vibration. For the analytical and experimental validation of the multi-modeelectromagnetic shunt damper, the first two modes of the cantilever beam are semi-activelycontrolled. In light of the frequency responses, the vibration and damping characteristics ofthe flexible beams with the electromagnetic shunt damper are investigated withreference to changes in the circuit parameters. Also, the time responses of theintegrated systems with an initial condition are experimentally examined forvalidation of the proposed damper. The effect of the magnetic intensity on the shuntdamping is studied by varying the gap between the aluminum beam and thepermanent magnet. The theoretical prediction of the frequency response of theelectromagneto-mechanically coupled beams shows good agreement with the experimentalresults. The present results show that the current-flowing electromagnetic shunt dampercan be successfully applied to reduce the multi-mode vibration of flexible structures.

Vibration Suppression of Flexible Beam Using Electromagnetic Shunt Damper

In this paper, the electromagnetic shunt damper was newly developed to passively suppress the vibration of the flexible cantilever beams. The electromagnetic shunt damper, which is electro-mechanically coupled with the flexible structures, simply consists of a coil, a permanent magnet, and an R-C circuit. The ends of the conductive coil are connected to the R-C series shunt circuit. The vibration and damping characteristics of the flexible beams with the electromagnetic shunt damper were investigated by tuning the circuit parameters. Also, the effect of the magnetic intensity on the shunt damping was studied with the variation of the gap between the aluminum beam and the permanent magnet. The theoretical model of electromagnetic shunt damper was validated with experimental results. Present results show that the magnet shunt damper can be successfully applied to reduce the vibration of the flexible structures.

A new electromagnetic shunt damping treatment and vibration control of beam structures

In this paper a new class of shunted electromagnetic damping treatment is proposed: anon-contact electromagnetic shunt damper (NC-EMSD). The NC-EMSD consists of anelectromagnet attached to a host structure, a permanent magnet attached to the fixedboundary and an electrical impedance connected to the terminals of the electromagnet.The electromagnet and the shunt impedance constitute a closed circuit. When the structurevibrates, an induced electromotive force will be produced and results in the electromagneticforce as damping force, which can suppress the vibration of the structure. The model ofNC-EMSD is built up based on the equivalent current method. The governingequations of the beam with NC-EMSD are established using Hamilton’s principle.The capacitor-matching-inductance (CMI) method and the negative resistivecapacitor-matching-inductance (NR-CMI) method are proposed, respectively. Then thevibration control of a cantilever beam with NC-EMSD is simulated and measured byCMI and NR-CMI control methods, respectively. The results show that boththe CMI and NR-CMI can attenuate the vibration effectively, and the NR-CMIprovides much better control performance than that by CMI. It is indicated as wellfrom the studies that the decrease of either the gap between the magnet pair orthe resistance of the shunt impedance contributes to the improvement of controlperformance.

Adaptive electromagnetic shunt damping

This paper presents a new type of passive vibration control: adaptive electromagnetic shunt damping. We propose a single-mode resonant shunt controller that adapts to environmental conditions using two different adaptation strategies. The first technique is based on minimizing the root mean square (RMS) vibration, while the second minimizes the phase difference between two measurable signals. An experimental comparison shows that relative phase adaptation performs better than the RMS technique.

Passive Vibration Control via Electromagnetic Shunt Damping

This work will present a new type of passive vibration control technique based on the concept of electromagnetic shunt damping. The proposed technique is similar to piezoelectric shunt damping, as an appropriately designed impedance is shunted across the terminals of the transducer. Theoretical and experimental results are presented for a simple electromagnetic mass spring damper system.

Control Orientated Synthesis of Electromagnetic Shunt Impedances for Vibration Isolation

A typical passive mechanical isolation system utilizes a mass-spring-damper as a mechanical filter. Active isolation control systems typically include an electromagnetic transducer to develop the required control forces. In this paper, the technique of sensor-less active shunt control is applied to a mechanical isolation system. An electrical impedance is designed and connected to an electromagnetic transducer with a view to minimizing structural vibration. Standard control tools can be applied to design the required shunt impedance. The technique requires no additional feedback sensors. Vibration of an experimental isolation apparatus is heavily attenuated by the application of an active shunt impedance.

Negative Inductor-Resistor Controller for Electromagnetic Shunt Damping 1

In this paper, we introduced a new type of electromagnetic shunt damping impedance. The proposed negative inductor-resistor controller is experimentally validated on a simple electromagnetic mass-spring-damper apparatus.