A Novel Power Inductor and Its Application for Compact, Large Current DC-DC Converters

This paper presents a novel power inductor for application in compact and large current DC-DC converters. This inductor uses a Fe-based alloy powder named NPA-F as the magnetic material and a straight, flat copper wire as the coil. The magnetic material and fabrication procedure together enable the proposed inductor to exhibit excellent performance. The inductance at 100 kHz is approximately 173 nH with a DC resistance of 0.17 mΩ. The inductor’s performance is compared with a commercial ferrite power inductor in a 40-A buck converter. The volume of this metal inductor is only 43.9% of conventional ferrite inductor. Moreover, the maximum converter efficiency at 1.5 MHz when using the proposed inductor is 0.5% higher than using the ferrite inductor. In other words, this downsized power inductor is able to operate in high frequency applications and helps large current converters achieve higher efficiency.