A quasi zero-magnetic-flux current sensor with large bandwidth for power semiconductor switches

The aim of this paper is to present a new current sensor intended for power semiconductor switches. The proposed sensor uses a current transformer associated with a very simple electronic circuit. This association allows a quasi zero-magnetic-field operation of the transformer to be achieved by means of an active compensation of the DC magnetising current. The proposed sensor provide isolated current measurements of both DC and AC components with a broadband response. Currents up to some hundred of amps can be measured with a good accuracy. After a quick review of the most used sensors, the principle of operation, features and implementation technique of the new sensor are presented. The performance characteristics of this device are illustrated by means of simulation and experimental results.