Wide Bandwidth PCB Rogowski Coil Current Sensor with Droop Suppression and DC Restoration for In-Situ Inverter Measurements

The use of wide-bandgap (WBG) semiconductor switches poses significant challenges for current measurement. To facilitate switch current measurement within the application, compact and high-bandwidth PCB-embedded Rogowski coil current sensors (RCCS) offer an effective solution. Previous approaches were subject to trade-offs between sensitivity and bandwidth in coil design as well as susceptibility to droop and parasitic offsets in the integrator design. In this paper, a rectangular coil design is optimized through FEM simulation for maximum bandwidth and sensitivity. An improved integrator concept is introduced to mitigate droop phenomena by enabling a low cutoff frequency, while preserving the signal DC component. A combination of active integration and self-integration through low-impedance termination enhances signal-to-noise ratio (SNR) for broadband measurements. The design is comprehensively validated. Initially, the frequency response is examined for the first time by monofrequent excitation ranging from 10 Hz to 75 MHz. Subsequently, the time-domain behavior is confirmed through measurements in double-pulse and buck converter setups.