Stability Analysis of Closed Loop Switching Power Amplifiers based on an Accurate Model of a Loudspeaker Installed in a Bass Reflex Enclosure

The purpose of this paper is to analyze the stability of closed loop switching power amplifiers using an accurate model of a loudspeaker installed in a commonly used bass reflex enclosure instead of the purely resistive model that can be used with a Zobel network. The model takes into account the electrical-mechanical-acoustical parameters of the transducer as well as the voice-coil loudspeaker´s non-linear behavior, avoiding stability problems when trying to compensate for the output filter stage, thus obtaining better THD figures. This model has been experimentally tested and then used to design a regulator for voltage-mode control method by means of MATLAB software. The regulator has been tested using a full-bridge power converter along with the proposed model of the transducer.