Magnetoresistive Point Field Detector-based Current Sensing for Power Electronics with Bandwidth Extension

Giant Magnetoresistive (GMR) point field detectors (PFDs) have been integrated into power electronic converters for high-bandwidth galvanically-isolated current sensing in conductors that are especially designed for magnetic field shaping. In this work, a methodology is introduced to sense currents in standard conductors with very high bandwidth by detecting the magnetic field as a vector in multi-dimensional space. Tools are developed to identify the field components in directions that do not have frequency-dependent changes arising from skin effect in the conductors. The importance of orienting the PFD in a particular point is identified as critical to the flat frequency response of current sensing. In this paper, bandwidth extension for busbar current sensing is experimentally verified by sensing the magnetic field using a rotated 1-D GMR as well as by computing the same magnetic field vector from orthogonal X and Y outputs of a 2-D GMR PFD. Current sensing bandwidth extension using the multi-dimensionality of the magnetic field leads to compact, low-cost current sensing without complicated conductor designs.