Subsea Power Electronics: Switching of an IGBT module in a subsea converter

Abstract

Global increases in energy demand will inevitable lead to increased oil and gas exploration in areas not considered economically viable today. In these areas with large depths and hostile conditions subsea system solutions will be beneficiary. Modifications of power electronic components not intended for subsea use might yield good solutions with decreased overall cost. One suggested solution for subsea converters is to encapsulate the power electronics in a vessel with flexible walls and filled with dielectric oil, allowing the pressure on the inside to equal the ambient pressure at sea bed. This solution will reduce overall cost and increase gas field recovery. Theoretical studies on various topics associated with subsea power electronics have been carried out. Among these are topics about subsea processing systems, considerations of condition assessment and working principle of semiconductors with emphasis on the insulated gate bipolar transistor, IGBT. The switching characteristics, including turn-on and turn-off transients and power loss calculations, of an IGBT module operated with two different gate drivers are obtained from double pulse tests with high voltage and current in an H-bridge leg converter set up. Thorough testing of the IGBT module and documentation of results have been performed to achieve well documentation of how the module behaves in air to use as a reference for later testing purposes with module submerged in dielectric oil and high pressure.