Technical Papers and Presentations

Coreless current sensors are increasingly adopted in electric-vehicle (EV) and power-electronics applications due to their compact size, low mass, and high bandwidth. However, removing the magnetic core and shielding places much greater demands on the design of the current-carrying conductor itself. Without a core to concentrate and shape the field, the busbar geometry becomes the primary lever for controlling sensor performance, and small changes in conductor shape can have an outsized effect on accuracy, bandwidth, and immunity to neighboring phases. This work presents a systematic geometric optimization of busbars for integrated-circuit (IC) current sensors based on Tunneling Magnetoresistance (TMR) technology. Finite-element-method (FEM) simulations, built on the Magnetic Fields physics interface in COMSOL Multiphysics, are used to evaluate and optimize electrical performance, inter-phase coupling, frequency response, and crosstalk between adjacent conductors, all while respecting mechanical integrability constraints imposed by the surrounding busbar assembly. Beyond busbar shape optimization, the FEM-derived magnetic field maps are used to determine the optimal placement of the TMR sensing elements relative to the conductor. Because TMR sensors respond to the in-plane component of the field along a single sensitive axis, positioning is critical. In this work, TMR microphysics (tunneling magnetoresistance ratio, bias dependence, noise, etc.) is not modeled explicitly; instead, the sensor is treated as an ideal magnetic-field probe with a defined in-plane sensitive axis, and its position is optimized purely from the geometric field distribution. This approach keeps the simulation tractable while still capturing the dominant, geometry-driven contributions to sensor behaviour. Overall, this work demonstrates a practical, simulation-driven methodology for developing coreless TMR current sensors suitable for demanding EV power-electronics environments, where compactness and multi-phase proximity make crosstalk mitigation a central design challenge. The approach combines busbar geometry optimization with field-based sensor placement, offering a reusable framework for future coreless sensor designs across different current ratings and phase configurations.