Flux-gate type non-contact current measuring device

Abstract

The present invention relates to a flux-gate type non-contact current measuring device for measuring a current to be measured by detecting an electromagnetic field around a conducting wire into which the current to be measured flows, wherein the present invention can detect a direct current component through a change of an oscillating signal by applying the oscillating signal for magnetizing two cores in mutually opposite polarities, wherein: an LC oscillation circuit is formed by using the inductance of a coil wound on one core, and the direct current component is detected by applying an LC-oscillating signal to a coil wound on the other core; an alternating current component is detected by using another core; compensated currents corresponding to the detected direct current and alternating current components are converged under a condition of offsetting a magnetic flux by the current to be measured, so that the current to be measured can be measured by measuring the compensated currents in the converged state thereof; and the present invention can normally measure a current by automatically demagnetizing an LC oscillating core even in a circumstance that the LC oscillating core is saturated by the current to be measured.

Description

technical field [0001] The present invention relates to a fluxgate type non-contact current measuring device that measures current by detecting an electromagnetic field around a wire in which current flows, and in particular, applies an oscillating signal that magnetizes two magnetic cores in opposite polarities, passing the oscillating signal The change of the DC component is detected by using the inductance of the coil wound on one of the magnetic cores to form an LC oscillation circuit, and the LC oscillation signal is applied to the coil wound on the other magnetic core to detect the DC component, and another magnetic core is used to detect the DC component. Detect the AC component, under the condition of offsetting the magnetic flux generated by the measured current, converge the compensation current corresponding to the detected DC and AC components, and detect the measured current by measuring the compensation current in this state, even if the LC oscillating magnetic I...

AI Technical Summary

Problems solved by technology

Therefore, the time constant varies with the magnetic properties of the core, and as a result, the core cannot be fully magnetized due to the application of a fixed-frequency oscillating signal that does not reflect the magnetic properties of the core, reducing the accuracy of current measurement

In order to overcome the above deficiencies, it is necessary to generate an oscillating signal that conforms to the magnetic characteristics of the magnetic core. However, due to the large error rate deviation of the magnetic core when making the current measuring instrument, it is difficult to make the circuit components that generate the oscillating signal suitable for the magnetic core, and it needs to be adjusted one by one. The current measuring instrument produced is not only troublesome, but also increases production efficiency and performance

[0007] In particular, in the prior art described above, in order to provide the magnetic cores on both sides with opposite polarities, the coils are connected in series (parallel when viewed from the connection node connected for inputting the oscillation signal), and then the oscillation signal is applied to the series connection of the two coils. node, so that the cores on both sides are magnetized in opposite directions, so just a small error in magnetization on both cores can cause a huge deviation in detection performance

[0008] At the same time, the above-mentioned prior art intends to magnetize the magnetic cores on both sides through the oscillating signal, but the measured current flowing in the wire also magnetizes the magnetic cores on both sides, and if the measured current is large, the magnetic cores will be damaged at the initial stage of detection. It will be saturated, and will oscillate at a high frequency much higher than the frequency of the vibration signal, so that the DC component cannot be detected by the fluxgate method

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