Boost converter design for ferrite core compatible with strong magnetic fields

Abstract

Boost converters with a ferrite core are widely used in neurostimulators. However, there may be some problems if it is used in a strong magnetic field because the saturation of the ferrite core leads to a serious decline in the inductance value. To evaluate whether a converter can work normally in a strong magnetic field, it is critical to obtain the lower limit value of the inductance of the converter. Besides, small inductance is easy to fit the small volume of a converter and is also safe in some special scenarios. Therefore, this paper is mainly devoted to establishing the minimum inductance design criterion of boost converters with a pulse load. The operational modes and equivalent circuit considering the parasitic resistance of boost converter components are presented. Then the mathematical formula for the minimal inductance value is derived through theoretical analysis of the components' current and output voltage. A digital simulation model of a boost converter is established to verify the theoretical analysis. Sets of comparison curves between the theoretical analysis and the simulation show that their results are in good agreement verifying the feasibility of the proposed method. The results in this paper provide theoretical support for the compatibility of converters containing a ferrite core inductor in a strong magnetic field and for the design requirement of a converter with a little volume inductor.