Analysis and design of a robust average current mode control loop for parallel buck DC-DC converters to reduce line and load disturbance

A robust control scheme for multi-module parallel buck DC-DC converters with average current mode control (ACC) is presented. The proposed loop adds an inner loop to the conventional current and voltage ACC loops, reducing the sensitivity of the outer voltage loop to the changing power stage parameters: number of modules, input voltage, load and component tolerances. The loop improves significantly the disturbance rejection of the converter, i.e. the closed loop output impedance and audiosusceptibility, while preserving the stability and the loop gain crossover frequency to a significant extent. The performance of the proposed scheme is demonstrated by both small-signal and large signal experimental results.