Scalable digital power controller with phase alignment and frequency synchronization

The trend in next-generation switched-mode power supplies will lead to modular, scalable solutions which deliver power efficiently over a wide range of operation. This paper details a new approach to introduce more advanced control features like phase-alignment and frequency synchronization into such scalable solutions. While these methods have been incorporated into multi-phase converters in the past, they all require the distribution of information among the individual converters. In distributed solutions, dedicated communication signals have been used to share this information. An advantage of the proposed method is that it does not require such communication signals between the individual power supplies and is therefore fully scalable and cost effective. Perturbances generated by the switching actions of the individual converters on the common input/output voltage are used by each converter to harvest information about the switching actions of its counterparts. An algorithm is proposed to align the individual phases and synchronize the switching frequencies based on this information. This allows a reduction of input/output capacitor ripple currents, similar to techniques used in multi-phase designs. Experimental results for an FPGA prototype implementation are presented.