A neutral leg independently controlled Current-Regulated Delta Modulator for four-leg switching power amplifier

In order to enhance integration degree and power density of the power amplifier, three-phase four-leg topology is adopted in this paper. A hybrid control method for this power amplifier, which can provide three independent currents, is described. In this method, the neutral leg is controlled separately from other three legs according the maximum and minimum values among three errors between three output currents and their respective reference values. The duty cycle of the upper switch in neutral leg yielded in this way can meet the needs of three output currents to the largest extent possible. Other three legs are controlled by Current-Regulated Delta Modulator (CRDM) to enhance dynamic performance of the power amplifier. This algorithm needs such a little mathematical operation that it can be conveniently accomplished with simple logic circuits and division processes circuits. The proposed control scheme is effectively validated by simulation and experimental results.