Current measuring device and current measuring method thereof

Abstract

The invention provides a current measuring device which comprises a magnetic ring, a coil, a sampling resistor, a driving voltage source, a comparator, a differentiator, a first feedback unit and a second feedback unit, wherein the first feedback unit is used for acquiring a first feedback signal on the sampling resistor; the first feedback signal can be electrically connected with one input end of the driving voltage source; the second feedback unit can be used for acquiring the first feedback signal on the sampling resistor; after the first feedback signal is subjected to differentiation processing, a second feedback signal is obtained; the second feedback signal can be electrically connected with one input end of the comparator; and an output of the comparator can be electrically connected with the other input end of the driving voltage source. Due to the adoption of the current measuring device disclosed by the invention, a reverse control point of an output voltage of the driving voltage source arranged in a nonlinear area of a BH curve (magnetization curve) of the magnetic ring can be close to a real intersection point of the nonlinear area and a linear area as far as possible, the measuring range of a current to be measured is expanded, the measuring accuracy is improved and meanwhile, the power consumption of the measuring device in the measuring process is reduced. The invention also provides a current measuring method and particularly relates to the current measurement of a direct current or an alternate current on the basis of a magnetic modulation principle.

Description

technical field [0001] The present invention relates to a current measuring device and a current measuring method thereof, in particular to a current measuring device and a current measuring method based on the principle of magnetic modulation, which are especially suitable for the measurement of Class B residual current of alternating current and / or direct current. Background technique [0002] The AC and / or DC current test method based on magnetic modulation technology has been widely used, which uses a driving voltage source to alternately set the working state of the magnetic core as figure 1 The linear and nonlinear regions of the magnetic core magnetization curve (also known as hysteresis curve, BH curve, hereinafter referred to as BH curve) are shown, and the intersection point of the linear region and the nonlinear region in the BH curve is judged (as shown by the dotted circle in the figure) is very important, which is beneficial to reverse the output voltage of the...

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Problems solved by technology

However, this solution also has limitations, because the feedback signal cannot accurately reflect the change of the coil inductance. When the measured current changes, the reversal turning point of the magnetic core will also change, which will affect the current measurement accuracy.

In order to increase the current detection range and prevent the turning point from entering the linear region, the turning point should be set as far away from the intersection of the linear region and the nonlinear region as possible, but this will result in higher power loss

At the same time, this scheme requires an amplification device connected to the input terminal of the sampling resistor, which increases the complexity of the circuit

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