High-Frequency Electromagnetic Behavior, Impedance Modeling, and Enhancement of Low-Permeability Powder Cores

In the high-frequency (HF) and high-power domain, powder cores have garnered significant attention due to their high saturation levels and low temperature sensitivity. Accurate modeling of powder cores is crucial for predicting HF behavior and optimizing performance. This paper provides a detailed examination of the material properties, internal composition, and electromagnetic behavior of powder cores, demonstrating that the assumption of perfect electric conductors (PEC) is inapplicable. Instead, powder cores should be modeled as dielectrics. The impact of various winding methods on powder cores is also investigated, showing how core capacitance is influenced by alterations in the electric energy distribution within the core. Given the inherently leakage inductance is discussed. By considering the full geometry of inductors, a comprehensive analytical model for powder cores at HF is proposed, thoroughly exploring its physical significance. Following the HF characterization of powder cores, a method to reduce parasitic capacitance is introduced. Then, a comparative analysis of both methods is presented, substantiating the efficacy of the proposed approach and the parasitic capacitance suppression technique through simulations and experimental validations across several scenarios. Finally, a 3D printing-based method to increase the HF performance of powder core is proposed and verified.