Current sensors that are meant to sense bidirectionally should be capable of detecting currents in opposite directions with the same sensitivity and bandwidth. Due to internal return path asymmetry or parasitic value effects, Rogowski coils with internal return paths may have slightly different responses to switch-current directions. Consequently, alternative differential coils with a variety of winding schemes and return paths must be analyzed to determine the source of the issue. By placing the sensors in two identical conditions but in opposite directions, one can determine whether the output varies. The study investigates the sensitivity and bandwidth of four differentially square-shaped helical coils with existing and proposed winding schemes in opposite switch-current directions. In the proposed winding scheme, the return path can significantly improve symmetry in the differential helical coil in terms of sensitivity for this purpose.
