The Zero Inductor-Voltage Converter

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Webb, Samuel Dylan
Power Electronics , DC/DC Converter , Data Center Power
Data centers and servers are one of the largest growing consumers of electrical power in the world today. In data center power distribution, the majority of the loss still occurs in the final conversion stages at the server rack, and server board level. A 48-volt architecture has been proposed, and adopted, that can reduce the power transmission losses by 16x compared with existing 12-volt architectures. This higher bus voltage presents a new set of challenges for power designers; this 48-volt bus must be converted down to a point of load voltage that is often lower than 1-volt. This thesis discusses several possible implementations of DC/DC converter circuits that can achieve the 48V to 1V conversion necessary to power today’s processors. Due to the fundamental challenges associated with single-stage conversion, the focus will be on implementations involving a two-stage conversion approach to achieve 48V to 1V conversion, also known as the Intermediate Bus Architecture. Presented in this thesis is a novel converter topology for the Intermediate Bus Architecture. The proposed topology, the “Zero Inductor-Voltage (ZIV) Converter” achieves several notable improvements over existing solutions found in the literature. It employs a multilevel, flying capacitor structure which reduces the voltage stress of individual components without the charge redistribution loss associated with switched-capacitor topologies. Additionally, the ZIV converter operates with very low reliance on magnetics, requiring only a small output inductor. This enables extremely high power density and efficiency of more than 99%.
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