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A novel half-bridge switching topology is presented which is based on using a split-wound series-connected coupled-winding inductor, interleaved switching, and zero-deadtime operation to achieve multilevel pulsewidth-modulation output with a reduced part count, reduced current ripple, and improved total harmonic distortion (THD) performance. This new topology is presented to highlight the design process for low-power high switching frequency designs requiring high performance, where circuit size and complexity are normally limiting factors. The design process demonstrated includes considering the current performance characteristics of the inverter and the design of the coupled-winding inductor. Design tradeoffs that are unique to this topology are explored that allow optimized designs for electrical performance, magnetic component size, or system losses. The benefit of the new topology is demonstrated using a case design for a class-D audio power amplifier, which shows a reduction in open-loop THD + N to as low as 0.29%.
Date of Publication: Nov.-dec. 2009