Constant‐flux inductor with enclosed winding for high‐density energy storage

Abstract

The 'constant-flux' concept has been described in a recent Letter as a way to utilise space more efficiently for inductor geometry with the core enclosed by winding. While the concept can conceptually be extended to the companion case of the inductor with winding enclosed by the core, structural synthesis is complicated by the absence of circular symmetry. Thus, this Letter delineates a procedure to shape the core and distribute winding turns to realise a magnetic field profile that is advantageous not only from the density standpoint, but also from the thermal standpoint via the reduction of hot spots, and from the reliability standpoint via the suppression of flux crowding. Design and fabrication results are delineated for a constant-flux inductor with the same specifications as a commercial counterpart, but the total height of the inductor is reduced by a factor of two.

Current and Potential Applications of Additive Manufacturing for Power Electronics

“…Typically, the core and winding for magnetic components are manufactured separately resulting in larger package size, longer lead times and performance limitations of the component [8], [9]. Proposed geometries, such as Cui and Ngo's [36] constant flux inductor, can reduce package size and increase component efficiency but require advanced methods of fabrication to be feasible, an opportunity where AM can be effectively applied. In addition to the methods of additive manufacturing, Ding et al [13] state that the AM methods are limited by the implemented feedstock material, rather than the specific manufacturing process for soft magnetic alloys.…”

Design and evaluation of the constant-flux inductor with enclosed-winding

“…Practically, R req is calculated from the loss budget and I req . The normalized h c can be obtained from the mechanical inputs include the footprint radius R c and inductor height H c using (8). The magnetic inputs determined by the material property include maximum magnetic flux density B max and permeability µ.…”

“…In order to improve energy density, a variety of techniques have been reported in the literature [1][2][3][4][5][6][7][8][9] to minimize inductor volume without sacrificing performance. The matrix inductor from [2][3][4] has low profile and good heat dissipation, but it encounters non-uniform flux density among elements which results in poor space utilization.…”

“…Recently, the concept of constant-flux inductor (CFI) was demonstrated in [7] aiming at improving the space utilization by making the flux uniform throughout the core volume. Based on the position of the core and the winding, the design of constant-flux inductor with enclosed-core geometry, such as toroids, was introduced in [8]; inductor with enclosed-winding geometry, such as injection-molded inductor, was discussed in detail in [9]. By following the design procedures given by [9], the flux distribution inside the core material is regulated by the uniformity factor α.…”