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NEPTUNE power system: startup power supply for 10 kV to 400 V Dc-Dc converters

NEPTUNE (North-East Pacific Time-series undersea networked experiments) is an underwater power and communications network for scientific experiments. It is proposed for the ocean floor of the Juan de Fuca tectonic plate in the Northeast Pacific Ocean. In the science nodes connected to NEPTUNE network, 10 kV to 400 V dc-dc converters are used to power various scientific instruments and underwater vehicles. The focus of this paper is the startup of the science node converters. The configuration of the NEPTUNE power system is introduced and the challenges of the system resulting from its location on the seafloor are addressed. The set of operations designed to start the 10 kV converters, which includes the control of the 10 kV switches connecting cables to converters, checking faults, and the starting of these converters, is described. These operations require a low voltage startup power supply which obtains energy directly from the 10 kV line. Several commonly used converter startup techniques are reviewed and their capabilities to solving this problem are discussed. Then the proposed circuit design of the startup power supply is presented. The circuit has been implemented and tested. Test results are provided