A new model for designing multi-hole multi-permeability nonlinear LTCC inductors

Nonlinear inductors have wide applications in DC/DC converters. The multi-hole multi-permeability nonlinear inductors have been proved to have gradually changing wide-range inductance curve while requiring no extra DC bias, which makes them suitable in various high efficiency DC/DC converters. This paper focuses on the design of such a multi-hole multi-permeability inductor. In the conventional design, complicated simulation needs to be executed when the coupling matrix among all the holes are taken into consideration. A dedicated model for calculating the inductance value is proposed in this paper to reduce the complexity. In the proposed model, the inductance simulation is simplified to calculating inductance of three basic units which are included in a nine-hole inductor. By simulating the nine-hole inductor, inductance of any rectangle shape multi-permeability nonlinear inductor with any number of evenly distributed holes on it can be calculated. Based on the proposed model, design guideline of the nonlinear inductor is also summarized. A sixteen-hole, two-permeability prototype is presented to demonstrate the design process according to the new model. The complete simulation and the test results are also provided to verify the model. The proposed model correlate with the simulation results very well.