Current Sharing in Digitally Controlled Masterless Multi-phase DC-DC Converters

This paper introduces modular masterless multi-phase architecture based on identical digitally controlled DC-DC converter modules that communicate over a digital bus. Advantages of the masterless architecture include simpler system configuration and development, and scalability to an arbitrary number of phases. Technical challenges are to facilitate proper phasing, control and current sharing functions, while minimizing data throughput requirements for the digital bus. A chain control algorithm is proposed to implement current sharing control in the modular masterless architecture. The algorithm performs a moving window averaging with relatively low storage and communication requirements. Implementations of the chain control in current-mode control systems and voltage-mode control systems are described in this paper. Experimental results are presented for a two-phase 12-V to 1.5-V, 15-A synchronous buck converter with digital voltage-mode control