Magnetic field measurement for contactless current sensing in power electronic converters

• The research aims to develop an efficient contactless magnetic field sensor for short circuit (SC) detection and current measurement in highly integrated converters. • Magnetic field mapping on the PCB identifies optimal positions for integration. • Induction coils present good candidates, not only for detecting SC stresses, but also for contactless current sensing with high frequency bandwidth and simple signal conditioning. • Current sensing through magnetic field measurement allows for easy and flexible integration into high-density integrated power converters, without the introduction of undesirable parasitic. Current sensing plays an important role in power electronics, for both protection and control of power electronic converters. This paper proposes an approach for detecting short-circuit (SC) events through the measurement of the magnetic field radiated by power converters. Two magnetic field sensor technologies (AMR sensor and induction coil) were evaluated. The induction coil system achieves a frequency bandwidth of 20 MHz with simple signal conditioning, whereas the AMR system is limited to about 1 MHz and requires more complex electronic conditioning. Magnetic field mapping over the printed circuit board (PCB) was performed to identify favorable positions for SC detection. Contactless current sensing was then evaluated on an EPC evaluation board based on GaN transistors. The results demonstrate that induction coil is a promising solution, not only for SC event detection but also for contactless current measurement in power converters. This work contributes to the development of integrated contactless current sensors for power converters or for intelligent gate drivers with SC or overcurrent protection integrated, especially dedicated to wide-bandgap devices such as GaN and SiC transistors, which often exhibit lower SC robustness compared to silicon devices.