Permanent Magnet Biased Inductors: And Additional investigations on: Biasing topologies for AC applications, Parametric transformers using permanent magnets, and Optimization of conduction losses on planar transformer windings

This thesis presents a compilation of research work, aimed at improving the design trade-offs and performance of magnetic components for power electronics applications. The thesis is divided in two parts.
The first and main part, is focused on the research of permanent magnet biased inductors, PMBIs, suitable for increasing the energy density of power inductors operating in DC applications. A 100% biased inductor can achieve the same inductance and current requirements with only half of the core’s area cross-section, or half of the required number of turns, compared to a standard non-biased inductor. In the main part of the thesis are covered, the basic theory background required for the design of PMBIs, the historical evolution of the PM and core topologies, and the main achievements and limitations found on the state-of-the-art documented PMBI implementations. A new topology of PMBI with improved characteristics has been developed and documented in this part of the thesis and in the attached publications P1, P2, P3 and P4. This new PMBI topology employs standard non-gapped UU cores and PMs and is proven to achieve 100% linear biasing in both ferrite and silicon-iron laminations cores. It has also been proven the possibility of achieving over-biased states, where the biasing flux has shifted the linear region of the core into high current levels, further increasing the PMBI’s energy density. The analysis and calculations required for the design of the PMBI topology has been approached using finite element analysis (FEMM) and MEC simulations. Several prototypes using the new PMBI topology has been implemented and empirically tested in common DC power inductor applications.
The second part of the thesis presents a summary of other brief investigations, related to magnetics components for power electronics. This second part includes research on: The possibility for a symmetric PM biasing topology, suitable for improving energy density of inductors for AC applications; A new topology of parametric transformer, PT with improved characteristics based on PM biasing. The new PM-PT topology has been physically implemented and documented on a journal publication, P5; And a practical investigation presenting a new design technique, suitable for reducing the conduction losses in high frequency planar transformer windings.