scholarly journals An Equivalent Circuit Analysis and Suspension Characteristics of AC Magnetic Suspension Using Magnetic Resonant Coupling

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 52
Author(s):  
Arifur Rahman ◽  
Takeshi Mizuno ◽  
Masaya Takasaki ◽  
Yuji Ishino
Keyword(s):  
Electrical Circuit ◽  
Magnetic Suspension ◽  
The Self ◽  
Wireless Power ◽  
Equivalent Circuit Analysis ◽  
Resonant Coupling ◽  
Secondary Current ◽  
Experimental Apparatus ◽  
Primary Current ◽  
Theoretical Results

The fundamental characteristics and performances of alternating current (AC) magnetic suspension using magnetic resonant coupling are studied analytically and experimentally. Nowadays, wireless power transfer to the suspended object is required during non-contact suspension in some applications. Therefore, magnetic resonant coupling has been introduced for AC magnetic suspension to achieve self-stabilizing magnetic suspension and energy transfer to the floator simultaneously. The effect of circuit parameters for developing an experimental apparatus and performances are predicted from the solution of the equivalent circuits analytically. First, an equivalent magnetic circuit is derived and analyzed to characterize the self-inductance and mutual inductance with the gap. Second, an equivalent electrical circuit is analyzed to derive the current and force equations including magnetic parameters of the circuit. The derivation of these equations is numerically solved to study the characteristics of the primary current, the secondary current, and the force with respect to the gap and the applied frequency. The comparison between theoretical and experimental results is depicted, and the reason for differences is explained. The experimental and theoretical results show that positive stiffness is possible, which is essential for achieving self-stabilization. The self-stability is confirmed by the frequency response of the suspension system to disturbance experimentally.

Compensating Resonant Frequency via Adjusting Adjustable Coil Automatically

2019 ◽  
Vol 12 (5) ◽  
pp. 432-438
Author(s):  
Jin Xu ◽  
Yuting Zhao
Keyword(s):  
Resonant Frequency ◽  
Power Transmission ◽  
Reference Value ◽  
Transmission Efficiency ◽  
Theoretical Research ◽  
Future Research ◽  
Wireless Power ◽  
Wireless Power Transmission ◽  
Resonant Coupling ◽  
Transmission Distance

Background: Detuning is the main problem that affects the efficiency and transmission distance of the resonant coupling Wireless Power Transmission (WPT). The distance of load and the offset of the load position could cause serious detuning. Methods: This paper presents an adjustable coil in which inductance can be adjusted. Then a model of WPT was established that could compensate resonant frequency automatically using the adjustable coil. Next, the relationship between the primary resonant frequency and the transmission efficiency is analyzed from the circuit. The analysis proved that the design of the adjustable coil could improve the transmission efficiency of the WPT system. Finally, a prototype of WPT system was built. Results: The experimental results showed that WPT system with adjustable coil can improve the transmission efficiency which proves the theoretical research. At the same time, it has essential reference value for the future research of WPT. Conclusion: In this paper, aiming at the system detuning caused by some other factors, such as the position shift of the load during the wireless power transmission, an adjustable coil is proposed.

Study of the Effect of Hole Clearance and Thread Fit on the Self-Loosening of Threaded Fasteners

2006 ◽  
Vol 129 (6) ◽  
pp. 586-594 ◽  
Author(s):  
Sayed A. Nassar ◽  
Basil A. Housari
Keyword(s):  
Analytical Investigation ◽  
The Self ◽  
Time Data ◽  
Experimental Procedure ◽  
Test Setup ◽  
Threaded Fasteners ◽  
Service Load ◽  
Real Time Data ◽  
Theoretical Results ◽  
Simplified Mathematical Model

This study provides an experimental and theoretical investigation of the effect of hole clearance and thread fit on the self-loosening of tightened threaded fasteners that are subjected to a cyclic transverse service load. An experimental procedure and test setup are developed in order to collect real-time data on the rate of clamp load loss per cycle as well as the loosening rotation of the bolt head. Three levels of hole clearance are investigated; namely, 3%, 6%, and 10% of the bolt nominal diameter. For the commonly used 2A thread fit for a selected bolt size, three classes of the nut thread fit are considered; namely, 1B, 2B, and 3B. A simplified mathematical model is used for the analytical investigation of the effect of the hole clearance and thread fit on threaded fasteners self-loosening. The experimental and theoretical results are presented and discussed.

SELF-ADAPTING FAÇADE SYSTEMS: EXPERIMENTATION REGARDING THE EXPLOITATION OF THERMAL DILATION

2020 ◽  
Vol 15 (4) ◽  
pp. 67-90
Author(s):  
Livio Petriccione ◽  
Fabio Fulchir ◽  
Francesco Chinellato
Keyword(s):  
Environmental Temperature ◽  
State Of The Art ◽  
The Self ◽  
External Energy ◽  
Building Envelopes ◽  
Orientation System ◽  
Thermal Dilation ◽  
Theoretical Results ◽  
Productive Development ◽  
Critical Aspects

ABSTRACT An original and innovative solar device orientation system is illustrated, together with the results of research and experimentation. The system proposed uses only the force generated by natural thermal dilation, without the help of motors, computerized devices or external energy sources, thus overcoming some critical aspects of the self-adaptive type of building envelopes used up until now. In the course of the research a mathematical model was developed to correlate the variation of the environmental temperature with the consequent expansion of the dilating elements of the system. The results of the tests carried out confirmed an excellent correspondence between the theoretical results and the experimentation. The state of the art of the research has all its theoretical aspects defined and some partial prototypes created. It is planned to build some complete prototypes with the realistic prospect of productive development.

scholarly journals Innovative Design of Drone Landing Gear Used as a Receiving Coil in Wireless Charging Application

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3483 ◽  
Author(s):  
Tommaso Campi ◽  
Silvano Cruciani ◽  
Francesca Maradei ◽  
Mauro Feliziani
Keyword(s):  
Near Field ◽  
Base Station ◽  
Electrical Circuit ◽  
Design Guidelines ◽  
Landing Gear ◽  
Electrical Performance ◽  
Secondary Coil ◽  
Wireless Power ◽  
Innovative Solution ◽  
Aluminum Pipe

A near-field wireless power transfer (WPT) technology is applied to recharge the battery of a small size drone. The WPT technology is an extremely attractive solution to build an autonomous base station where the drone can land to wirelessly charge the battery without any human intervention. The innovative WPT design is based on the use of a mechanical part of the drone, i.e., landing gear, as a portion of the electrical circuit, i.e., onboard secondary coil. To this aim, the landing gear is made with an adequately shaped aluminum pipe that, after suitable modifications, performs both structural and electrical functions. The proposed innovative solution has a very small impact on the drone aerodynamics and the additional weight onboard the drone is very limited. Once the design of the secondary coil has been defined, the configuration of the WPT primary coil mounted in a ground base station is optimized to get a good electrical performance, i.e., high values of transferred power and efficiency. The WPT design guidelines of primary and secondary coils are given. Finally, a demonstrator of the WPT system for a lightweight drone is designed, built, and tested.

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