A Novel Control Strategy of the Class-D Stereo Audio Amplifier

This paper presents a class-D stereo audio amplifier that controls directly the current of speakers using three phase full bridge circuit. And a new switching method for the current control of the amplifier is proposed. The proposed switching strategy is an improved version of the dead time minimization method, which can reduce current intermittence that commonly occurs with the conventional dead time minimization method whenever the current changes polarity. Dead time is not always adapted in the proposed method, which makes it different from the conventional practice of applying dead time in every current polarity changing point. In this paper, the specific strategy for the stereo operation is discussed. With the experimental results, usefulness of the control strategy is confirmed.