DC-to-DC buck converters with novel current mode control

Abstract

This paper presents a novel current mode control technique for DC-to-DC buck converters to provide dynamic robustness. The inductor current and the diode current are fedback and combined in a specially nonlinear way which makes the average inductor current proportional to the current control signal and only determined by the current control signal. Stability analysis is performed by the root-locus method, which reveals that the current control loop is inherently stable. When the voltage feedback loop is closed, the output of the voltage error amplifier is used as the control signal. A PI controller is used to regulate the output voltage. The audio susceptibility and closed loop output impedance are presented. Experimental results demonstrate that the inductor current is not affected by large disturbances in supply voltage or output load and the buck converter with the proposed current mode control exhibits excellent performance.