Applied methods of power supply and galvanic isolation of gate drivers of power transistors in bridging end stages of Class D amplifiers and inverters

Abstract

Various methods used for a floating high-side gate drive power supply and galvanic isolation of the Class-D amplifiers and different DC-AC or DC-DC converters have been reviewed and evaluated in the paper. On the basis of the literature, the bootstrap floating supply and self-boost charge pump topology for a gate drive high-side power supply, as well as control signal isolated systems with optically-isolated signals or with capacitive signal isolation have been described and compared. New topologies of the Class-BD amplifiers with Common-Mode (CM) free outputs using PSC PWM - Phase Shifted Carrier Pulse Width presented in the paper, shows that almost all gate drivers of the output stage transistors require floating power supply and galvanic isolation of the control signals. In the case of such circuits with multi-level PWM output, the most reliable and robust method for the floating gate drive power supply and galvanic isolation is self-boost charge pump topology with capacitive control signal isolation. Correct operation of the output stage of the proposed Class-BD amplifiers as well as the PWM modulator and self-boost charge pump topologies with capacitive control signal isolation have been verified using intensive Pspice simulation.