Decentralized Control for a Fault-Tolerant, Fully Scalable Microprocessor Power Supply for Spacecraft Applications

This paper presents a decentralized control method applied to a multiphase synchronous buck converter powering a microprocessor for a space application. The main objective is to remove the classic centralized controller which represents a single point of failure and to offer full modularity/scalability for the converter design. The complexity of the control part to address a large number of converter phases is simplified and the system is able to reconfigure itself with a different number of phases easily. This control method increases the level of functional safety of the converter and guarantees full availability of the delivered power if a fault occurs. The principles of the proposed solution are presented and a description of the analog building blocks of the controller implemented into an Application Specific Integrated Circuit (ASIC) is provided. Then, early-stage analyses of the voltage loops, the balancing functions, and the control signal interleaving are introduced taking into consideration the performance of the converter. Simulation results using Cadence™ OrCAD PSpice tool for the study of a 12V/1.2V 40A 250 kHz 4-leg multiphase converter are shown. They demonstrate the stable operation of the converter, the large bandwidth obtained for the regulating loops, and the possible reconfiguration modes offered by the scalability of the system.