Hönschel J, Schwanninger R, März M (2025)
Publication Status: Submitted
Publication Type: Unpublished / Preprint
Future Publication Type: Journal article
Publication year: 2025
DOI: 10.36227/techrxiv.176704921.14560921/v1
In high current power electronics applications, power transistors are often connected in parallel to enhance efficiency and achieve higher system power. When connecting power transistors in parallel resonant circuits can occur due to the parasitic parameters of the printed circuit board (PCB) and the transistor itself. These resonant circuits cause oscillations, resulting in higher switching losses or even device damage. This paper describes an approach to detect and suppress oscillations when connecting two gallium nitride (GaN) high electron mobility transistors (HEMTs) in parallel. The model is formulated in state-space form, and the eigenvalues of the system matrix provide a pole-based stability criterion that distinguishes differential mode oscillations between the paralleled devices from common mode oscillations of the full half-bridge. Based on this approach, parameter maps are derived that relate system stability to the source inductances, the gate inductances, and the output capacitance of the transistors. The analytical predictions are verified by LTspice simulations with manufacturer models and double-pulse measurements on a dedicated hardware demonstrator. The results show that increasing source inductance strongly promotes differential mode oscillations, while the gate inductance exhibits a finite range of values in which the system becomes unstable. Within this range, oscillations can occur even for perfectly symmetric gate inductances. The existence of a dedicated operating point further confirms that the output capacitance of the transistors and the DC-link inductance can cause common mode oscillations.
APA:
Hönschel, J., Schwanninger, R., & März, M. (2026). Parasitic Oscillation Analysis of parallel connected GaN-Transistors. (Unpublished, Submitted).
MLA:
Hönschel, Julien, Raffael Schwanninger, and Martin März. Parasitic Oscillation Analysis of parallel connected GaN-Transistors. Unpublished, Submitted. 2026.
BibTeX: Download