Modular interleaved ZVS current fed isolated DC-DC converter for harvesting high altitude wind power

Three phase low voltage power is generated using an air-borne wind turbine and electric generator in a high altitude wind power (HAWP) generation system supported by light gas filled blimp/aerostat. Generated power is transmitted at an optimal medium voltage DC to reduce the weight of an electro-mechanical tether and to increase the transmission efficiency. A 100 kW isolated DC to DC converter is proposed which converts DC link voltage to an optimal transmission voltage. Modified interleaved current fed converter is designed which gives zero voltage switching in the primary side for a wide range of load. Converter is interleaved to reduce the device rating, conduction loss and the size of passive components used in the converter. Two modules of insulated gate bipolar transistor (IGBT) H-bridge are connected in parallel in primary side and four modules of full bridge diode rectifier are connected in series in secondary side. Two extra IGBT switches for zero voltage switching (ZVS) are used to design clamp circuits for the proposed converter. This modular concept simplifies the design procedures of converter at high power level and improves the stray losses associated with in the converter. The steady state analysis of the converter is carried out and verified with the simulation results and presented in this paper. Device ratings and passive components size are determined using the steady state analysis for 100kW HAWP generation system.