A Non-Invasive DC-10-MHz Wideband Current Sensor for Ultra-Fast Current Sensing in High-Frequency Power Electronic Converters

Abstract

To enhance the performance of the converters along with improving their efficiency and miniaturization in many power electronics applications, a need for higher switching frequency is highly demanded. In high switching frequency converters, due to high common mode voltage issue, wideband, isolated, and low loss current sensor is required for the robust control design and ultra-fast protection. In this paper, we propose a non-invasive hybrid, isolated, and loss-less wideband current sensing method applicable for high-frequency power converters (dc-10 MHz). The proposed hybrid current sensing scheme combines two different isolated sensing technologies-a magnetoresistor sensor and a differential Rogowski coil sensor, which have complementary characteristics to achieve a wide sensing bandwidth. The proposed hybrid current sensor also utilizes planar magnetic field concentrators (MCON) using conductive materials to normalize the non-uniform magnetic field distributions generated by the current over a wide frequency range. We demonstrate through hardware prototypes and experiments that the proposed hybrid sensor yields to a very high sensing bandwidth of dc to 10 MHz. The performance of the proposed hybrid sensor is also evaluated in a 1-MHz dc-dc converter as well as a high-frequency H-bridge inverter module.