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

This project designed and evaluated a half‑bridge switching module that uses four Gallium Nitride high‑electron‑mobility transistors (GaN HEMTs) in parallel. Paralleling can increase current capability but makes the circuit sensitive to parasitics—unwanted inductances and capacitances—so their impact was studied carefully. Based on this analysis, three module layouts were created. Parasitic inductances and capacitances were estimated with the finite‑element tool Ansys Q3D and included in detailed LTspice simulations that also captured device non‑linearities. To cut down the large number of simulations required, an automated workflow linked LTspice with Matlab, enabling looped runs with varied component values and the use of optimization methods to select suitable components. The three designs were then verified with laboratory double‑pulse tests. One design switched at 400 V and 50 A, but failed at 60 A. Another showed unwanted ringing on the gate‑source voltage, likely due to excessive gate‑loop inductance. The results highlight both the challenges of paralleling GaN devices and the usefulness of model‑based optimization for power module design.

Dette projekt designede og evaluerede et halvbro‑koblingsmodul, der bruger fire galliumnitrid høj‑elektronmobilitets‑transistorer (GaN HEMT'er) i parallel. Parallelkobling kan øge strømhåndteringen, men gør kredsløbet følsomt over for parasitter—uønskede induktanser og kapacitanser—så deres indflydelse blev undersøgt nøje. På baggrund af denne analyse blev tre modul‑layouts udviklet. Parasitære induktanser og kapacitanser blev estimeret med finite‑element‑værktøjet Ansys Q3D og indarbejdet i detaljerede LTspice‑simulationer, som også tog højde for komponenternes ikke‑lineariteter. For at reducere det store antal nødvendige simulationer blev der opbygget et automatiseret flow ved at koble LTspice med Matlab, så der kunne køres løkker med varierede komponentværdier og anvendes optimeringsmetoder til at vælge egnede komponenter. De tre design blev derefter verificeret med dobbeltpuls‑tests i laboratoriet. Ét design skiftede ved 400 V og 50 A, men fejlede ved 60 A. Et andet viste uønskede ringninger på gate‑source‑spændingen, sandsynligvis forårsaget af for høj gate‑sløjfeinduktans. Resultaterne fremhæver både udfordringerne ved at parallelkoble GaN‑enheder og nytten af modelbaseret optimering i design af effektelektronikmoduler.

[This apstract has been rewritten with the help of AI based on the project's original abstract]

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

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