Design and Analysis of Mega-Watt Power Converters Enabled by 10 kV SiC MOSFETs

Abstract:
Generation of electrical energy from thermal, nuclear has continuously produces the CO2 and radioactive waste. To meet the carbon-neutral target for the solution of global warming, many countries have taken measures to the use of renewable energy[1]. One of the most popular renewable is wind power. It is estimated that about 24% of European Union’s eclectricity comes from wind power[2]. What’s more, the demand of application like electric ships, traction, data center distribution, fast charging station, power to other kind of resources such as hydrogen is growing. At present, commercially available solution in wind turbines used the low voltage Si IGBT[3][4]. However, In these high power conversion system, the power loss on bus bar, cable can be reduced by converting the power directly under medium-voltage(2kV to 10kV), for instance, three level neutral point clamped converter has been applied[5]. While, 10 kV Silicon Carbide(SiC) MOSFET based solution is drawing much attention, which makes the converter simpler with 2-level converter topology, and lower power loss compared with Si devices. So far, GE Haliade-X has built 14MW offshore wind turbine under mdium voltage[6]. The MVolt project in Aalborg University is proposed to meet this need for sustainable electricity in high power medium voltage(MV) application, of which the goal is to design Grid-connected Medium Voltage Induction Machine System based on 10kV Silicon Carbide(SiC) MOSFET.
However, some drawbacks arise if no specified methodology applied with MV SiC MOSFET. Fast switching speed on the one hand can reduce the converter volume, on the other hand noise caused by large dv/dt on parasitic capacitance matters too much, the design challenge of the noise cancelling from device level and system level are both significant, that should be in terms with the package design and converter design. What’s more, large power loss produces much thermal problem, the other one of the design challenge is how to measure the power loss and build a smart thermal management system. Moreover, the mega-watt converters control will be applied, where the chanllenge is to ensure the safe operating, such as soft start, instant protection, low EMI noise.
So the main objective of this PhD project is to demonstrate feasible and reliable Medium Voltage Mega-Watt Power Converters Enabled by 10 kV SiC MOSFETs. High frequency back to back converter and power cycling system with smart thermal management will be built in Aalborg University. The main outcome of the Ph.D. project would contribute to the efforts in solving the technical problems in MV Mega-Watt Power Converters design under high switching frequency, practical thermal issue and robust operation.

Funding: AAU Scholarship