Small-signal analysts of a PWM boost DC-DC converter with a non-symmetric phase integral-lead controller

Abstract

An extensive small-signal analysis of a single-loop voltage mode-control strategy for a pulse-width-modulated (PWM) boost DC-DC power converter operating in continuous conduction mode (CCM) is proposed using a new nonsymmetric phase controller. To model the boost power stage, a linear circuit model is used which includes all parasitic components such as the equivalent series resistance (ESR) of the filter capacitor, the ESR of the inductor, the transistor ON-resistance, and the diode forward resistance and offset voltage. The proposed control scheme introduces a new nonsymmetric phase integral-lead controller. The controller can provide a peak phase boost of up to 165/spl deg/, with its phase returning to 0/spl deg/ at high frequencies. This phase characteristic is much improved over that of a commonly used symmetric phase integral-lead controller which provides -90/spl deg/ of phase at high frequencies. The new controller characteristics provide increased gain margin and phase margin for a DC-DC power converter. Open-loop and closed-loop circuit models and transfer functions are derived for the boost PWM power converter and illustrated by Bode plots.