Digital Average-Ripple-Based Control Techniques for Switching Converters With Fast Transient Performance

Abstract

Digital average-ripple-based (AR) control techniques, which are categorized in digital average inductor current (DAIC) control, digital average voltage (DAV) control, and digital average voltage/digital average inductor current (DAV/DAIC) control, for buck-type converters, are investigated and analyzed in this article, and digital average voltage/digital average capacitor current (DAV/DACC) control is subsequently proposed. Among them, the proposed DAV/DACC control using dual-edge modulation exhibits fast transient performance and has high output-regulation accuracy even without a digital compensator. The control laws of digital AR controls with dual-edge modulation are derived and their stabilities are investigated by sampled-data modeling. It is concluded that the stability of the digital AR controls for the buck-type converter is better than that of peak-ripple-based (PR) controls and valley-ripple-based (VR) controls, where the stability of DAV/DACC control and DAV/DAIC control can be further enhanced by adjusting current-feedback ratio. The quasi digital average voltage (QDAV) control is further proposed to provide fast transient performance for the boost-type converter. A series of relevant simulations and experiments are given to verify the theoretical analysis.