A current sensor of high accuracy fit for precise and exact motion control

A current sensor of high-accuracy fit for precise and exact motion control, particularly appropriate for the control of an AC-servo drive system, is presented. The proposed sensor, named for the sensing principle it uses, is called the magnetic-field-controlled type and has the ability to fulfil the following specifications: (i) the sensor is a noncontacting type; (ii) the operating frequency ranges from DC to several hundred hertz; (iii) the dynamic range can be extended from several milliamperes to 100 A; (iv) a detection accuracy of 0.01% full-scale is guaranteed over the whole range; and (v) a sensor of the same detection characteristics is easily obtainable and is applicable to each phase current sensing for three phases.<>