Improvement of High-Frequency Characteristics of Small-Size Toroidal Reactors with New Wire Guides

Abstract

In this paper, a new reactor with a wire guide for a small-size toroidal core that can be used in the high frequency range is proposed. Theoretically, the reactor size can be reduced in proportion to the switching frequency. However, practically, as the switching frequency is increased, reactors are affected by the parasitic capacitance existing between the windings and between the winding and the core, and the inductance characteristic of the reactors is deteriorated. Therefore, there is a limit to increasing the switching frequency. This paper proposes two types of wire guides, namely a two-layer winding guide and a three-layer winding guide, to reduce the parasitic capacitance. Moreover, the impedance characteristics of the reactors using the proposed wire guides are evaluated. The wire guides are manufactured using a 3D printer and attached to the center hole of the toroidal core. With the proposed guides, the parasitic capacitance decreases by 0.73 times and 0.66 times compared with the conventional reactor. The linear regions of the impedance, which can be regarded as a pure inductance, are enlarged. In addition, the materials of the wire guide are also evaluated. It is shown that the ultraviolet curing resin guide is superior to the thermoplastic resin guide.