Permanent magnet biasing, is a known technique for increasing the energy storage capability of inductors operating in DC applications. The opposing flux introduced by a permanent magnet will extend the saturation flux limit of a given magnetic material. When full biasing of the core is achieved, the effective saturation current limit of a given inductor is doubled. This results in a smaller requirement in number of turns and area cross-section, allowing for smaller and/or more efficient inductors. By adding some switching elements, the benefits of biased inductors can also be used in AC applications. This paper presents a review of the scientific literature on biased hybrid inductors and the evolution of the used magnets and cores configurations. A recently developed biasing configuration, the saturation-gap, will also be analyzed and the design parameter will be identified using finite element software. The simulation results will be compared with empirical laboratory measurements on physical units.

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The use of permanent magnets for bias magnetization is a known technique to increase the energy storage capability in DC inductors, resulting in a size reduction or increased current rating. This paper presents a brief introduction on the different permanent magnet inductor's configurations found in scientific literature. A new biasing configuration: The Saturation-Gap, will also be presented, simulated and experimentally tested.

Parametric transformers are magnetic components which employ a variable inductance to generate parametric oscillations in a secondary resonant tank. Power conversion with parametric transformer can provide constant output voltage regulation, short-circuit protection, input over-voltage and under-voltage protection, and bidirectional filtering. In spite of these benefits, parametric transformers did only experience small scientific attention during the 1970s. Due to the low energy density and low efficiency of the topologies developed at the time, parametric transformers were discarded in favour of the more common power converters based on the magnetic amplifier. In spite of the great developments in power semiconductors, magnetic amplifier control still remains a competitive option in present-day power electronic applications benefiting from its high robustness. This publication presents a new topology of parametric transformer based on permanent magnet (PM)-inductors, presenting higher efficiency and higher energy density. Finite element method magnetics simulations are used to analyse the variable inductance mechanisms. A physical prototype is developed and tested empirically in an AC/DC power converter. The prototype verifies all the mentioned benefits of parametric power conversion, and presents an efficiency and energy density equivalent to presently employed solutions for voltage regulation, using power semiconductor magnetic amplifiers.

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