An Integrated TMR-Based Current Sensing Solution for WBG Power Modules and Converters

This article proposes a contactless and high-precision current measurement solution using tunneling magnetoresistance (TMR) sensors to address the challenges of current measurement in wide bandgap (WBG) power electronics with high dv/dt, di/dt and switching frequencies. The solution, referred to as two TMR sensor (TTS), utilizes TTSs placed on opposite sides of the current-carrying trace, which can be printed circuit board (PCB) or bus bar-based. At first, the derivation and working principle of the TTS technique is presented, followed by its design and validation on an in-house developed SiC-based power module and power converter. A slitted PCB terminal design with minimum parasitic capacitance is proposed for the power module to alleviate skin effects and simplify sensor placement. The slitted terminal design is tested at 50 A and 70 kHz square wave pulse. Similarly, for the power converter, a bus bar-based TTS design is developed and compared with the existing shunt-based current measurement in continuous testing at 500 V and 3.5 kW. The TTS solution outperforms the shunt measurement with high SNR and bandwidth.