Tunneling magnetoresistance sensors for high fidelity current waveforms monitoring

This paper addresses the problem of current monitoring in resonant power converters for overcurrent protection. Since the demand for higher power density suppliers is constantly growing, resonant power converters (RPC) have been receiving more and more attention recently, due to its high efficiency and high switching frequency capability. However, to make practical use of this approach there are still crucial issues, such as overcurrent protection of converter components. Therefore, it is required to implement dedicated protection methods based on a quick feedback loop and additional, modern design solutions. To ensure high reliability of any protection method, as well as to implement new solutions in power electronics, novel current monitoring techniques and sensors are needed. Thus, in this study we present high fidelity magnetoresistive current sensors for monitoring MHz signals with extremely low nonlinearity (< 0,015%), hysteresis (close to 0%) and phase shift (close to 0°). The remarkable effectiveness of the proposed sensors was confirmed by monitoring three different, MHz current waveforms, typically occurring in RPCs with different overcurrent protection methods FFT results clearly emphasize superb signal reproduction, which enables the using of the tested sensors in modern high speed, power electronics applications.