Light-load power management in differential power processing systems

Differential Power Processing, Series Stacking

Das, Dipanjan

关键词: Differential Power Processing, Series Stacking;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/107867/DAS-DISSERTATION-2020.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Series stacking is used as a means of implicitly raising DC bus voltages without additional power processing and has been explored widely in the context of photovoltaic sources and batteries in the past. More recently it has also been explored in the context of server loads and microprocessor cores. Supplying power at a higher voltage supports a reduction in conduction losses and reduces complexity in power supply design related to the high current at low voltage nature of microprocessor loads.However, series stacking of DC voltage domains forces the dc voltage domains to share the same currents. In the context of series stacked loads, this would lead to failure of voltage regulation of individual dc voltage domains. Additional power electronics, commonly referred to as differential power processing (DPP) units are required to perform this vital task. The idea is to let the DPP converters (which need to have bidirectional capability) process the difference between currents of adjacent voltage domains, so that the load voltages are regulated. Although series stacking and DPP has been explored in significant detail, the importance of light load efficiencies of these DPP converters has not been highlighted enough in the past. In this document we discuss the importance of light load control in common series stacked systems with DPP and propose a light load power management scheme for bidirectional buck-boost converters (which is the building block of most DPP converter topologies). Extending efficient operation load range of converters (to process higher power in rare heavily mismatched conditions and to maintain good light load efficiencies at the same time) with multiphase converters and asymmetric current sharing is also discussed in the context of DPP converters. We finally propose to build a series stacked system of low voltage loads and DPP regulators to demonstrate the advantages of series stacking as opposed to the conventional parallel connection.