2.1-Channel Switching Amplifier With DC/High-Frequency-AC Mixed Power Supply for Efficiency Improvement and Bus Voltage Pumping Elimination

Compared with traditional two-stage class-D audio amplifier, audio amplifier based on cycloconverter-type single-stage inverter (CSSI) has advantages of high efficiency and no bus voltage pumping (BVP). However, CSSI requires complex active clamp circuits for the current commutation of cycloconverter, especially for multichannel amplification. In this letter, a 2.1-channel switching amplifier with dc/high-frequency-ac (HFAC) mixed power supply is proposed, where CSSI is used as low-frequency audio channel amplifier and two class-D amplifiers are used as high-frequency audio channel amplifiers. With dc/HFAC mixed power supply, the proposed 2.1-channel switching amplifier does not require additional active clamp circuits for current commutation of cycloconverter. Besides, wide range soft switching of cycloconverter switches can be achieved. Benefiting from single-stage power conversion of low-frequency audio channel and wide range soft switching of cycloconverter switches, high efficiency of the proposed 2.1-channel amplifier is achieved. Without BVP, low voltage stress of switches and low distortion of low-frequency audio signal are realized in the proposed 2.1-channel amplifier. A 200-W prototype is presented to verify the analysis results.