Performance limitations of random current-sharing parallel-connected converter systems and their solution

A study of a random current-sharing power converter system is presented. The system is comprised of many DC/DC power converters connected in parallel. Each power converter has its own single control loop operating in either the voltage regulation or current-limiting mode. Performance limitations are discovered through system simulation. Nonuniform current sharing occurs despite voltage droop characteristics that facilitate near-uniform current distribution. Due to random mismatches in component values, uneven current sharing among power converters exists. This causes system performance characteristics to exhibit large variations and system current sharing is found to be far from uniform, resulting in poor system reliability. The achievement of near-uniform current distribution, stiff system output voltage and the reduction of the output impedance variances are also discussed.