PCB-Embedded Helical Coils’ Return Path Utilization for Bidirectional Switch-Current Sensing

PCB-Embedded Rogowski coils are particularly suitable for high-bandwidth current sensing in many applications due to their electrically contactless nature, the absence of a magnetic core (thus resulting in smaller sizes and no saturation), and their ease of integration. Rogowski coils can generally be manufactured using an air or PCB core, plus the circuitry of the integrator or processor. This is while, the physical characteristics of the coils and the layout quality of the sensing system can affect the overall accuracy of the measurement in PCB-embedded Rogowski coils. Particularly, winding arrangement and symmetry directly impact the coil's parasitic values, which may limit the coil's measurement bandwidth and current-direction independence. The present study examines the relationship between electrical and physical properties of a helical PCB-embedded differential coil. As an alternative to the conventional winding scheme, a double-winding scheme is modified to reduce undesirable sensing effects associated with the coil's parasitic values. Experimental results from trapezoidal switching current captures on two different Rogowski coils will demonstrate the effectiveness of the revised winding scheme.