High Response and High Accuracy Current Sensor Constituted by Using Magnetic Core

Vector control in induction motor drive system gives a theoretical foundation for realizing high accurate torque control. However, the control accuracy in practice depends on the performances of voltage and current sensors used for the purpose. Particularly, the current sensor is required to satisfy the following: (i) It is non-contacting type; (ii) The detectable frequency range covers from DC to the one beyond over the inverter chopping frequency; (iii) The current range over from mA to several 10 A has to be covered with the accuracy of 0.1% in FS (Full Scale); (iv) The same detection characteristics is easily obtainable for the application to each phase in three phases; (v) The effect of the environmental temperature variation on the detection characteristics is small; (vi) The sensor is little affected by the external magnetic noise and surge voltage.This paper presents a current sensor which has a possibility of satisfying almost all the above items by using two magnetic cores.