At present, the requirements for the design and cost of inductors are becoming increasingly high with the continuous development of high-efficiency and high-power UPS and inverter devices for meeting the market requirements and enhancing the competitiveness. The size of a core increases accordingly with the increase of the size of the inductor. However, the cost is very high to manufacture a one-piece and large-volume core. Therefore, it is usually adopted in the prior art to splice a plurality of smaller blocks into a larger core in a splicing way, and the resulted core is generally referred to as an integrated inductor.
FIG. 1 shows such an integrated inductor. As shown in FIG. 1, this integrated inductor comprises a first winding C1 and a second winding C2 connected to each other. Each of the first winding C1 and the second winding C2 wraps around a respective internal core (not shown in FIG. 1), and the two internal cores corresponding to the first winding C1 and the second winding C2 are connected by means of two external cores M located outside the windings in order to achieve a communicating magnetic circuit, wherein the distribution of the magnetic induction lines is shown substantially as the dashed arrow of FIG. 1. The external cores M need a relatively large volume. However, the manufacturing cost is very high if each of the external cores M is made of a one-piece and large-volume material. Consequently, in order to reduce the cost, each external core M is usually formed by splicing six small-volume cuboid-shaped sub-cores a, b, c, d, e and f.
However, there will be gaps between the sub-cores inevitably even if the sub-cores are spliced very closely, such as a gap G1 substantially perpendicular to the magnetic induction lines, and gaps G2 and G3 substantially parallel to the magnetic induction lines. Such gaps will result in flux leakage, which may cause a certain degree of eddy-current loss to the metal near the inductor and ultimately result in the increase of power consumption of devices comprising such inductors.