A Hybrid Calculation Method for Determining the Frequency Characteristics of the Air-Cored Coils with Complex Structure

Hollow coils with complex structures are very common in electrical equipment and sensors. Additionally, the responses at different frequencies are an important characteristic of the coils. However, it is quite challenging to divide the irregular coils with fine windings (thousands of turns and wire diameter less than 0.2 mm) into meshes using finite element simulation software (FESS), much less perform the simulation calculations, as theoretical derivations are only applicable to coils with specific shapes. This issue presents challenges in designing coils with high-density, multi-turn and irregular structures. Thus, we propose a calculation method for determining the frequency characteristics of hollow coils with such structures. To validate this method, three sets of hollow coils with complex structures and high-density winding were fabricated. These coils included two coupled PCB coils, one coil with thousands of fine turns, and a PCB coil with a complex and were tested using an LCR analyzer with a frequency range of 0 to 2 MHz. The experimental results showed good agreement with numerical calculations.