Zero-flux microcurrent sensor

Abstract

A compensation method of current sensor includes real-time detection of magnetic induction density and outputting current with proper phase and magnitude via the feedback circuit for tracking compensation of the exciting current in magnetic core. A zero-flux microcurrent sensor designed based on the method has two superposed annular working magnetic cores and auxiliary magnetic core with wound primary coil, secondary coil and compensating coil as well as shielding and protecting casing outside the magnetic core. The microcurrent sensor features the primary and secondary coils on the superposed core, the secondary coil with load across it, one detection coil on the working core, a compensation coil on the auxiliary core, electronic regulating circuit comprising amplifier and voltage-to-current converter connected between the detection coil and the compensation coil.

Description

technical field [0001] The invention relates to a current sensor (transformer) for electrical measurement, in particular to a zero-flux micro-current sensor widely used in precision measurement in industrial field equipment and power systems. Background technique [0002] Current sensor is a widely used electrical measuring instrument. There are a large number of current sensors in industrial field equipment, primary protection and control circuits of power systems. The basic requirements for current sensors are: high accuracy, relatively flat error curve, good ability to resist external electromagnetic interference, and long-term stability. The above requirements are more important for high-precision micro-current sensors (mA level, μA level). As we all know, the current sensor realizes the energy transmission through the magnetic induction coupling between the primary coil and the secondary line, and its error is caused by the excitation curr...

AI Technical Summary

Problems solved by technology

(see Figure 5 ) But the above compensation current I cannot be provided by the original current sensor, it needs to be injected externally, and it is provided by the excitation of the auxiliary magnetic core by the external current source

Chinese patent 95201568.4 discloses a compensation structure: an auxiliary magnetic core superimposed on the main working magnetic core is set, the primary coil and the secondary coil are wound on the two superimposed magnetic cores, and an auxiliary magnetic core is wound on the working magnetic core. There is a compensation coil and a compensation resistor indirectly at both ends of the compensation coil. Although the above structure improves the measurement accuracy of the current sensor, its disadvantage is static compensation, which cannot track the change of the excitation current in real time.

Images