Design procedure of a 14.4 kV, 100 kHz transformer with a high isolation voltage (115 kV)

A Novel Oil-Immersed Medium Frequency Transformer for Offshore HVDC Wind Farms

“…Bahmani (Chalmers) in his work published has in 2016 [9] has presented a design for a shell type coaxial windings 666 kW, 1/2 kV transformer as one stage of 15 series connected DC/DC converters. The total rating of the turbine is 10 MW, the turbine's output voltage is 1 kV and the output voltage of the farm is 30 kV (see Figure 2-2).…”

“…Claimed HV insulation to ground 15 kV @ 16 Jaritz et al (ETH) in their paper, published in 2017, have explained the design of an MFT having a high voltage isolation of 115 kV [9]. The transformer is 0.4/14.4 kV, 10 kHz.…”

“…Huang et al have compared foil type winding with Litz windings and explained how an interleaved winding structure can lower the maximum electric field intensity and what is the limitations to do this in their work published in 2017 [11]. Jaritz et al (ETH) in their paper, published in 2017 [9], have explained how different winding configurations can help with achieving minimum insulation stress. However, none of these have considered a lower breakdown and higher aging under a high frequency square wave regime.…”

“…Jaritz has presented a list of possible solid insulation materials that can be used as barriers in different places in the transformer [9]. However, the comparison is limited to the AC situation based on permittivity of the materials as the voltage distribution at DC steady state is based on conductivities.…”

“…One the most serious attempts reported in literature for the insulation design of a prototype power electronic transformer is reported by Jaritz et. al [9]. He has reported the design and manufacturing of a 0.4/14.4 kV MFT with 115 kV insulation at its HV side to ground for the new linear collider at the European Spallation Source (ESS) in Lund (2.88 MW pulse modulators with pulsed output voltages of 115 kV).…”