Small saturating inductors for more compact switching power supplies

Abstract

Other than by reducing power, extending battery life in portable microelectronics amounts to increasing power efficiency, which, when coupled with accuracy, translates to increasing filter inductance. The problem with higher inductances is that magnetic cores require more space to prevent the onset of saturation, so accuracy and efficiency (via their need for bulky inductors) hamper the miniaturization benefits gained from chip integration. This paper illustrates the time-domain and efficiency effects of inductor saturation in switched-inductor DC-DC converters and shows how they can accommodate saturation (with up to 65% reduction in inductance) with minimal impact on battery life and accuracy. Extending the useful range of an inductor in this fashion not only reduces the printed circuit board (PCB) area and volume to a fraction (e.g., 30-50%) of what an otherwise larger unsaturated inductor would require, but also helps bridge the integration gap that enables practical system-on-chip (SoC) implementations.

Inductor Saturation Compensation in Three-Phase Three-Wire Voltage-Source Converters via Inverse System Dynamics-II

“…by setting the disturbance signal to zero for command to output frequency response characterization. The synchronous frame control voltage v dq in (6) and 7is the sum of the output of the PI compensation of the current error and the cross-coupling decoupling term which is given by…”

“…Inserting 8into 7and (6) and expanding the derivative term one can obtain the closed-loop current control dynamics for CSCC and IDMBC methods in s-domain respectively as…”

Online Estimation of the Current Ripple on a Saturating Ferrite-Core Inductor in a Boost Converter

“…Recent studies [14][15][16] showed that it was possible to design smaller and lighter SMPS by exploiting ferrite-core inductors operating in partial saturation. In this situation, the inductance drops as the inductor current increases, with a strong dependence on the core temperature (at higher temperatures, the inductance starts dropping for lower current values).…”

Characterization of Non-linear Inductors Including Thermal Effects for Power Applications

“…This issue is of great interest both for scientists and industry due to economic reasons tied both to the initial cost of the converter and to the reduced payback time of the equipment [1]. The value of the inductor in power converters is often considered constant with the current both for static and State Space Averaging analysis [2,3]; recently some papers dealing with the use of inductors working in partial saturation [4][5][6][7] have been published. In [8,9] the thermal model has been considered as well.…”