Digital Average Current-Mode Control of PWM DC–DC Converters Without Current Sensors

This paper introduces a digital average current-mode control technique for pulsewidth modulation dc-dc converters which only rely on voltage sampling. The proposed approach is to estimate inductor current using first-order discrete-time low-pass filter; therefore, the controller can calculate average inductor current in every switching cycle. As a novel technique of predictive average current control, it has been investigated by choosing an appropriate duty ratio to regulate valley inductor current first and then eliminating error between the estimated average inductor current and a reference current in succedent switching cycle. The algorithm is based on a two-loop control structure to achieve an accurate voltage regulation and is derived for three basic converters: buck, boost, and buck-boost. The validity of the proposed approach has been demonstrated by simulation and experimental results on a dc-dc boost converter.