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By axially loading of a cylindrical wire we utilize the first order buckling mode to form the shape of a segment of a wire loop inductor. The shape of the deformed wire is expressed in analytical form and provides the basis for a semi-empirical formulation of the loop inductance. Combining several buckling segments and taking advantage of the snap-through behavior of such a segment, the shape of the wire loop in air and hence the loop inductance can be varied mechanically on purpose. The analytical model for the tunable inductance enables a design methodology for bistable compliant inductors. We present two designs of mechanically tuned inductors in the range from 20nH to 50nH. Furthermore the electromagnetic properties of the proposed innovative components are confirmed by method of moments numerical modeling based on quasi-static magnetic fields and by experiment. We finally show that the design process is applicable to regular plane polygonal inductors representing multi-stable compliant stages.
A mechanically tunable planar single-turn inductor in air is proposed. The bistable flexible deflection of axially compressed wire segments is used for variation of the loop area of regular polygonal loop inductors. We present analytical expressions for the loop inductance and confirm the theoretical findings by magneto-quasi-static field simulation on exemplary polygonal circuits.
The variation of the contact impedance of adhesive conductive EMI shielding tapes under high temperature storage (HTS) of 110degC is investigated. The adhesive tapes under test are implemented as signal return paths in microstrip lines. Changes in the ground plane impedance by adhesive deterioration are analyzed by S-parameter measurements from 1MHz to 3GHz. A circuit model for contact impedance degradation is proposed and applied in simulation of board level shielding. Contact resistance and contact capacitance are found to increase significantly after 2400h, causing a declined magnetic field shielding effectiveness by 30 dB below 500 MHz.
Enhanced inductive power transmission (IPT) between coaxially arranged circular coils is introduced by time-modulation of the mutual inductance. This modulation is accomplished by coherent switching of the short circuit current induced in a third loop. An analytical circuit model supporting the design for future time-modulated IPT systems is derived. We demonstrate an increase in load rms-voltage by 13% (28% gain in power) compared to an unmodulated transfer on an experimental system operating at fundamental frequencies ranging from 40kHz to 500kHz.
A Planar Magneto-Inductive Device with Modulated Mutual Inductance for Wireless Power Transmission
(2023)
A Magneto-Inductive Wave (MIW) structure for wireless power transfer (WPT) is proposed with switchable mutual inductance between neighbored coupling coils. Orthogonally placed switchable short circuit loops are added in order to modulate the wave propagation properties of the MIW structure without changing the resonance frequency. We derive an analytical model based on lumped circuit analysis for the MIW waveguide and successfully evaluate the theoretical findings by circuit modeling and field simulation. We demonstrate switchable, i.e. addressable, guided wireless power transfer along an experimental MIW structure at a resonance frequency of 20.5 MHz.
We introduce a quick and accurate quasi-static magnetic field scanning technique by employing a progressive sampling method in an unconfined input space. The proposed
machine learning algorithm is tested against uniform sampling on a printed circuit board test structure. We prove allocation of multiple, separated regions with predefined tangential field strengths at MHz frequencies. The feasibility of equivalent magnetic dipole source modeling based on a small number of samples is demonstrated. Compared to uniform testing, progressive expansion sampling detects contours of given field limits in less than 3% of the reference measurement time.
The automotive industry is pushing power electronic packaging to higher operating and heatsink temperatures while still requiring very high power densities due to limited space. Currently, the power electronics that is implemented within the engine compartment of the vehicle must operate with heatsink temperatures of approximately 85/spl deg/C and this temperature can be expected to increase to 125/spl deg/C in the near future. The high temperature operation of the power electronic structure is fundamentally limited by the employed materials maximum temperatures. A packaging concept is introduced that describes a structure realisation that enables the materials to operate at high ambient temperatures without exceeding their individual maximum temperatures. This in turn allows the complete power electronic structure to operate at a higher system temperature. In this paper, the packaging concept that can be used to meet these difficult requirements of high temperature and high power-density is introduced, discussed and implemented. Two case studies are considered and implemented to illustrate the packaging concept.