Design and Optimisation of a Half-Bridge Switching Module With Parallel GaN HEMTs for High Power Applications Using Finite-Element Analysis

Zäch, Mike Robin ; Olsen, Simon Holt ; I Gardi, Sigmundur

4. term

Energy Engineering, Master

2021

2021-05-28

146 pages

The main objective of this project was to design a half-bridge switching module with four GaN HEMTs in parallel. The parallel operation of GaN HEMTs was analysed to understand how the parasitics would affect the operation. Three different designs were created, based on the previous analysis, using a digital design process with the FEA software Ansys Q3D to calculate the parasitic content. These parasitics were then implemented in an LTspice model to account for all the parasitics and non-linearities in the designs. This process was further optimised to minimise the number of simulations needed as the parallel designs required a high number of iterations per design. A method of integrating LTspice with Matlab was developed, where a simulation could be looped, with each iteration containing different component values. Using optimisation theories, the components could be evaluated, and an optimal component could be selected. The switching performances of the three designs were tested in the laboratory with a double pulse test, where one of the designs switched at 400V and 50A, but a failure occured at 60A. Undesired ringings on the gate-source voltage were observed in one of the other designs, which is thought to be caused by too high gate loop inductance.

GaN HEMT ; WBG ; Digital Design ; Half-Bridge ; DPT

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