Large Inductance Variation Research Articles

Emergent magneto-inductance effect in permalloy thin films on flexible polycarbonate substrates at room temperature

Emergent inductance has attracted significant interest for its relevance in both interesting fundamental physics and practical applications in magnetic devices that demand miniaturization without compromising inductance. In this Letter, we report the discovery of a stepwise magnetic field-induced emergent magneto-inductance (EML) effect in Permalloy (Py) thin films deposited on polycarbonate (PC) substrates. Remarkably, Py/PC devices exhibit an exceptionally large inductance variation exceeding 1 μH at room temperature, and intriguingly, a sign reversal of inductance occurs around the zero magnetic field. The dependencies of the EML effect on frequency, step magnetic field changes, and film width can be explained from the theory based on the spin motive force driven by transient domain wall motion. This study opens up exciting avenues for advancing our understanding of emergent inductance in fundamental physics and paves the way for practical applications in flexible magnetic devices.

Characteristic of a Variable Inductor Using Magnetorheological Fluid for Efficient Power Conversion

This paper proposes a new variable inductor for efficient power conversion which consists of the ferrite core and the gap filled with a magnetorheological fluid. Its main feature is to show a large inductance variation versus inductor currents even with a simple inductor structure and so it leads to improving light and intermediate load efficiency of power conversion systems compared with the conventional inductor with an air gap. To predict the characteristics of the variable inductor, the nonlinear magnetic permeability of the magnetorheological fluid used is accurately measured because the inductance value strongly depends on the magnetic nonlinearity of the fluid. With the obtained B-H curve, a 1 kVA variable inductor is designed and analyzed with three-dimensional finite element method taking into account the losses of the core and the fluid. Finally, to prove the feasibility and usefulness of the proposed inductor, a prototype inductor is fabricated and its experimental results are compared with numerical ones.

Radio Frequency Micro Electro Mechanical Systems Inductor Configurations for Achieving Large Inductance Variations and High Q-factors

To determine a micro electro mechanical systems (MEMS) inductor configuration that gives large inductance variations and high Q-factors, air-suspended MEMS inductor configurations are studied: (a) an inductor with two angularly meandered lines, (b) a solenoid inductor with a pair of movable shields, (c) a planar spiral inductor with a patterned shield of different areas, and (d) a planar spiral inductor with a metallic frame of different sizes. The configuration of (a) is shown to give a large inductance variation of 115%. However, its Q-factor is only about 10, and difficulties in fabrication are also expected. The configuration of (b) could be a reasonable engineering solution. The inductance variation is 67%, and the maximum Q-factor is over 22. The solenoidal inductor configuration is thus considered suitable for realizing an RF MEMS variable inductor with large inductance variations and high Q-factors.

Influence of inductance variation on performance of a permanent magnet claw pole soft magnetic composite motor

Winding inductance is an important parameter in determining the performance of electrical machines, particularly those with large inductance variation. This paper investigates the influence of winding inductance variation on the performance of a three-phase three-stack claw pole permanent magnet motor with soft magnetic composite (SMC) stator by using an improved phase variable model. The winding inductances of the machine are computed by using a modified incremental energy method, based on three-dimensional nonlinear time-stepping magnetic field finite element analyses. The inductance computation and performance simulation are verified by the experimental results of an SMC claw pole motor prototype.