New modular two stage switching converter for high power stereo audio amplifier

This paper proposes a novel topology of a two independent channel switched audio high power amplifier. A three-branch inverter, two high frequency isolation transformers, two output high frequency cycloconverters and two low-pass filters, compose the basic topology. This architecture has the advantage that the inverter middle branch is common to both channels of the amplifier, without compromising the channel independency, and reducing the number of devices. The objective is to obtain a compact, high power density and reliable system. This Single Conversion Stage Amplifier topology integrates in a single unit both the power supply and the D-class amplifier, conferring to the total system direct and more efficient power conversion and compactness due to the component reduction. Since the amplifier outputs are totally isolated, modular operation is possible among several amplifier units or even between the two channels of a same unit. The amplifier output filter specifications could be relaxed because the principle of operation duplicates the equivalent switching frequency. Another advantage is that the output cycloconverters switch with zero voltage, reducing switching losses. The proposed topology is described and analysed, with emphasis in the principle of operation, modulation techniques and design criteria. The experimental results verify the theoretical analysis.