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|A 6.5kV IGBT Development Module for Renewable Energy Systems|
|Keywords: SiC, Power, high voltage|
|A three-stage structure for 20kVA SST as Fig.1 shows has been proposed in , it has bi-directional power transfer capability and interfaces to 12kV distribution voltage with center-tapped 120V single phase output. The SST consists of a cascaded high voltage high frequency AC/DC rectifier that converts 7.2kVac to three 3.8kV DC buses, then this voltage is stepped down to 400V, and converted to 240/120V 60Hz AC by a voltage source inverter(VSI). The switching device for high voltage side needs 6.5kV IGBT module, however, currently commercialized 6.5kV IGBT has a large current ratings which is not suitable for our applications, so a new high voltage, low current H-bridge IGBT module package is required for the current SST project. According to safety standard IEC1287, the electric insulation test must be carried at AC voltages up to [equation].So for a 6.5kV IGBT, 10.2 kVrms voltage should be applied to test the insulation. Insulation is highly depending on the thickness, material and homogeneity of the insulation on the chip bottom. Fig.2 shows a typical vertical structure of an IGBT module on heatsink. The substrate should be able to sustain 10.2kVrms voltage strength. Fig. 3 gives the maximum attainable isolation voltage for different isolation substrates and today’s standard substrate thickness d. 0.63mm AlN substrate is selected for our design. The chips and substrate will be covered by silicon gel which provides enough insulation capability between all high voltage and low voltage conductors above the substrate. (This paper presents the design results for a first-generation module for the SST application [to be described in more detail] and presents a summary of design guides of interest to the IMAPS audience.)|
|Gangyao Wang, Ph.D. Student
North Carolina State University