GaN-Enabled Three-Phase PFC-Rectifier Family in CCM-Boost Mode Employing Only Two HF-Switches and Inductors for Low Common Mode and Simplified Power Architectures

• Applicant: Dr.-Ing. Frank Schafmeister
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462843442

To supply electronic or electronically controlled loads of high power demands of the kW-range from grid, three-phase rectifiers converting 3ac into dc power are essentially required. In order to preserve the public ac-grid resources, reactive power components therein are to be avoided by massive usage of Power Factor Correction- (PFC-) rectifiers employing power transistors as turn-off switches. Today’s three-phase PFC rectifier generate considerable common-mode (CM) electromagnetic interference (EMI) noise showing high-frequency components (HF) directly originating from the switching frequency of their power transistors. A crucial conflict arises since raising switching frequencies therefore distinctively increase the size of the required EMI filter (its CM-stage) while they reduce the differential-mode (DM) noise and the physical size of other passive components, which contribute in similar shares to the total rectifier volume. However, low weight and low volume are the key metrics especially for mobile applications, such as on-board charging in e-mobility. The proposed project targets at the theoretical and practical in-depth analysis of new three-phase PFC rectifier topologies being characterized by a low CM-noise emission level due to avoiding HF-noise generation upfront. This basically enables to fully utilize GaN-HEMTs with highest switching frequencies in three-phase rectifier applications distinctively shrinking the size of the passive components in their main power stage while at the same time keeping their EMI-filter small (low DM- and low CM noise) promising ultra-compact overall designs. The underlying basic concept is practically enabled only by combining the unidirectional GaN-HEMTs for HF-switching with a further set of monolithic bidirectional GaN-switches. These are commutated softly with low frequency and therefore do exploit the minimized conduction losses while nearly eliminating the impact of the inferior HF-switching behavior of this new switch technology. Finally, two hardware demonstrators, exemplary developed for the application field of on-board charging, shall be presented: A non-isolated low-CM three-phase rectifier with > 98 % efficiency and an isolated variant with 97 % efficiency, each targeting at > 30 % size reduction compared to state of the art systems.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2312: Energy Efficient Power Electronics "GaNius"