Unified Equivalent Modeling for Stability Analysis of Parallel-Connected DC/DC Converters

Abstract

A unified equivalent modeling approach is proposed for enabling simple and effective analysis of stability of parallel-connected buck converters. Two kinds of active currentsharing schemes are considered, i.e., the master-slave scheme and democratic scheme. By applying elementary transformation to the Jacobian of the averaged model, two decoupled subsystems (which determine common-mode and differential-mode stabilities, respectively) have been found, irrespective of the specific type of active current-sharing scheme. From the decoupled subsystems, the parameters of interest that affect different stability issues are clearly identified. Results from this work greatly simplify the stability analysis and design of parallel-connected dc-dc converters.

Team-Oriented Load Sharing in Parallel DC–DC Converters

“…The transfer functions from any input variable perturbation to any output variable perturbation can be found using the conventional circuit theory. Since parallel buck converters are prevalent in the literature [4], [10], [11], [19], [27], the controller performance is studied for buck converters. The proposed method, however, is general and applicable to different converter systems.…”

“…P ARALLEL dc-dc converters are used in highperformance low-voltage applications since they reduce component stress, improve reliability and availability through structural redundancy, accommodate high-conversion ratio, reduce voltage ripple through interleaving of switching patterns, and simplify thermal management [1]- [4]. Lower rating of dc-dc modules provides the designer with more freedom in component selection [5], [6].…”

“…However, they require a tight voltage regulation to properly distribute load current, otherwise, it can potentially overload a converter [7]. Active sharing techniques have received more attention, e.g., master-slave [1], [4], [10], [11], circular chain [12]- [14], common-duty-ratio [15]- [17], and sensorless current mode [18] techniques. The goal is to share the load among different converters proportional to their current ratings or, equivalently, to equalize the per-unit currents, which is referred to as the proportional load sharing.…”

“…Master-slave method is widely adopted in the literature [1], [4], where a single converter (master) regulates the output voltage while the other converters (slaves) follow the masters current. With identical converters, the master can produce the duty command and relay that to other converters [15]- [17], e.g., through RF transmission [10].…”

Mathematical modelling and analysis of transient and steady states of buck dc‐dc converter in DCM

“…As the DC-DC converter is modeled, the performance of the elements of the converter as well as the performance of the converter in different operation modes can be investigated in the transient and steady states. Modeling of the DC-DC converter has received a considerable attention and various technical papers have been published in this field (Wu and Chen, 1998;Kondrath and Kazimierczuk, 2010;Capel et al, 1983;Guinjoan et al, 1993;Yousefzadeh, 2010;Chetty, 1982;Li et al, 2010;Maksimovic and Zane, 2007;Ma and Smedley, 1997;Sun et al, 2001;Ramos and Saldana, 2000).…”