Improved zero-flux type large bandwidth current sensor

The design and evaluation of a current sensor circuit with improved stability of the sensitivity is presented. The proposed solutions are based on a feedback loop, for the DC and low frequency signals, through the magnetic circuit only. The Hall sensor and the feedforward amplifier are kept with maximum gain in the loop. The Rs/(Rc+Rs) factor due to the flux dispersion is compensated at high frequencies. The circuits differ in increasing trimming facility, minimal amount of active components and no intermediate tap simpler coil design. The three circuits have been designed in order to minimise the total amount of components. The prototypes show a wide operating frequency range from DC to 1.4 MHz, ±10 A or 0 to 20 A measurement range, as well as an accuracy of ±1%