High Efficiency Medium Voltage to Low Voltage Wireless Power Transformation for Data Centers

Wireless power transfer (WPT) techniques have been widely explored for various applications including for electric vehicles (EVs) and mobile phones. Less attention has been paid to the use of WPT in power distribution applications. An isolated wireless power link enables a touch safe interface without electrically energized contacts eliminating any arc flash or electrocution hazards. This concept will for example enable safe medium voltage distribution inside data centers eliminating low voltage distribution with its large bus bars and cables and bring voltages larger than 1kV directly to the server rack. It has been demonstrated that a converter using a planar contactless transformer can directly convert the 1kV DC input to 48V over a wide load range. In this paper, the planar contactless transformer is optimized with 3D printed bobbins to improve the manufacturability and technology readiness level. A new synchronous rectifier architecture is developed with MOSFET drain-to-source voltage-sensing for an H-bridge rectifier to improve the DC-to-DC efficiency. An adaptive dead time control method is used to compensate for layout parasitic inductances, to maximize the synchronous rectifier efficiency, and to avoid premature turn-off of MOSFETs. The DC-to-DC power transfer efficiency and loss distribution are analyzed.