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Designs for the inductive components of a novel multilevel half-bridge inverter topology are presented, for an experimental high-bandwidth audio amplifier application. The design of the coupled-inductor component is examined to give a compact design by using a gapped-ferrite toroid with minimal impact to system losses over the full range of the amplifier output. The impact of using the topology with the coupled inductor on the design of the output filtering inductor is also examined to allow a significant reduction of the physical size of this component when using lossy powdered-iron materials to design a highly linear low-pass filter. In combination with the ferrite-core coupled inductor, the total magnetic weight of the experimental design is shown to be reduced at 20 g total, compared to the required filter inductor at 30 g for the same design by using a standard inverter topology with similar total losses. In addition, the analysis presented points to methods which can be used to further optimize the size and losses of these components.
Date of Publication: Oct. 2009