US-12625166-B2 - Current measuring device

Abstract

The present disclosure relates to a current measuring device comprising: a plurality of unit modules which are provided with mutually different grounds and are connected in series; a power unit which supplies high-voltage DC or AC power to the plurality of unit modules via a line; and a current sensor which measures a current flowing through the line.

Inventors

• Jeong Woo LIM

Assignees

• LS ELECTRIC CO., LTD.

Dates

Publication Date

20260512

Application Date

20220314

Priority Date

20210423

Claims (4)

1. 1 . A current measuring device, comprising: a plurality of unit modules which are provided with mutually different grounds and are connected in series; a power unit which supplies high-voltage DC or AC power to the plurality of unit modules via a line; and a current sensor which measures a current flowing through the line, wherein the current sensor is provided with a ground from an adjacent unit module that is closest to the current sensor among the plurality of unit modules such that a voltage difference between a measurement point and a ground terminal of the current sensor is equivalent to a voltage drop across the adjacent unit module.
2. 2 . The current measuring device of claim 1 , wherein the current sensor is a low-voltage current sensor.
3. 3 . The current measuring device of claim 1 , wherein the current sensor measures a current value by selectively using one or two current sensors according to the current flowing in the line.
4. 4 . The current measuring device of claim 1 , further comprising: a control unit for controlling the current sensor by determining an operating state of the current sensor based on a current value measured by the current sensor; a display unit for displaying the current value measured by the current sensor; an external device for allowing a manager to monitor the operating state determined by the control unit; and communication unit for connecting the control unit and the external device.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a National Stage of International Application No. PCT/KR2022/003542, filed on Mar. 14, 2022, which claims priority to and the benefit of Korean Patent Application No. 10-2021-0052982, filed on Apr. 23, 2021, the disclosure of which is incorporated herein by reference in its entirety. FIELD The present disclosure relates to a current measuring device, and more specifically to a current measuring device which is capable of measuring a current value by using a low-voltage current sensor in a system through which a high-voltage direct current or alternating current flows. BACKGROUND The content described in this section merely provides background information for the present exemplary embodiment and does not constitute the related art. In general, there are various methods for measuring the magnitude of a current, but the most commonly used measurement method is a method of using a current sensor to which a core and Hall elements are applied or a current sensor to which a shunt resistor is applied. The current sensor to which a core and Hall elements are applied generates a magnetic field around the line in proportion to the amount of an input current flowing through the line or bus bar, and it is a method of calculating the magnitude of an input current by measuring the output voltage generated by the magnetic field by using the Hall elements. However, since the strength of the magnetic field that can be accommodated according to the inherent material properties of each core, that is, the limit value is set, when the limit value is reached and the saturation state is reached, there is a problem in that it cannot be measured even if the amount of input current increases. The current sensor to which a shunt resistor is applied measures a current flowing through the resistor by measuring the voltage across both ends of the resistor based on Ohm's law. However, since the current flows directly through the current sensor to which a shunt resistor is applied, Joule heat (Joule heat=12R) is generated by the flowing current, which makes it difficult to be used in a device through which a large current flows. In order to reduce the Joule heat, the resistance value must be lowered to the level of several to tens of microohms (μΩ), and in this case, since signals that can be sensed also become smaller together, there is a problem in that measurement is impossible or errors increase. In addition, both ends of the current sensor to which a shunt resistor is applied must be connected to a measurement circuit, and if a high-voltage power grid voltage is directly connected to the measurement circuit, there is a risk of electric shock, and if it is connected without circuit insulation, there is also a problem in that it may result in shunts (short circuits). Therefore, a preferred method for measuring the value of a current flowing in the line is to use a current sensor that meets the standards of a current flowing in the line. That is, in order to measure the current value of a line through which a high-voltage direct current or alternating current flows, it must be measured with a high-voltage current sensor. FIG. 1 schematically shows the configuration of a current measuring device for measuring a current value by using a conventional high-voltage current sensor. Referring to FIG. 1, the conventional current measuring device includes a power supply unit 10, a current sensor 20 and a plurality of unit modules. Herein, the plurality of unit modules are provided with different grounds and are connected in series, and the power supply unit 10 supplies high voltage DC or AC power to the plurality of unit modules through lines. In this case, the current sensor 20 is a high-voltage current sensor, and it can measure a current value flowing through the line by receiving an individual ground (GND). Herein, since the current sensor 20 is driven by receiving an individual ground (GND), the insulation voltage applied between the current sensor 20 and the line becomes the same as the voltage of the power supply unit 10. However, the high-voltage current sensor has a problem in that the sensing sensitivity is inferior to that of the low-voltage current sensor, because it requires an additional insulation design for the line and the use of an insulating device. Another method is to increase the insulation voltage of a low-voltage current sensor to manufacture and measure a new current sensor, but this consumes a lot of money and the manufacturing method is also very difficult. Accordingly, the situation is that it is necessary to introduce a current measuring device that can measure a current by minimizing the insulation voltage between the line through which a high-voltage current flows and the low-voltage current sensor by using a low-voltage current sensor without a special insulation design or insulation device. SUMMARY Accordingly, in order to solve the problems of the related