Current measuring device of low-voltage circuit

Abstract

The utility model discloses a current measuring device for a low-voltage circuit, which comprises a power supply circuit, a load circuit, a tandem magnetic bead, a voltmeter and an electronic load, and is characterized in that one end of the tandem magnetic bead is electrically connected with the power supply circuit; the other end of the tandem magnetic bead is electrically connected with one end of the load circuit; the negative electrode end of the voltmeter is electrically connected with a point A at one end of the tandem magnetic bead; the positive electrode end of the voltmeter is electrically connected with a point B at the other end of the tandem magnetic bead; the positive electrode end of the electronic load is electrically connected with a point B at the other end of the load circuit; and the negative electrode end of the electronic load is electrically connected with a C point at one end of the load circuit. Therefore, the high-precision voltmeter and the electronic load are adopted, the current value of the electronic load is changed, the voltage difference of the series magnetic bead FB1 is measured, and the accurate current value is obtained through calculation according to the variable quantity of the voltage difference and the variable quantity of the load current.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of vehicle-mounted field controller especially relates to a current measuring device of low voltage circuit. BACKGROUND

[0002] In the field of vehicle-mounted field controller, the SOC (System on Chip) has the characteristics of low power supply voltage and large current, which mainly comes from its dual demand for high efficiency and low power consumption. Therefore, it is usually necessary to measure the low power supply voltage and large current of the SOC in the field of vehicle-mounted field controller. The traditional measurement method has the following problems:

[0003] 1. The current clamp error is too large,

[0004] 2. The series connection of the ammeter will cause the output voltage to drop due to the internal resistance of the meter, which cannot meet the working voltage of the SOC, resulting in the system unable to work. INVENTION CONTENTS

[0005] The utility model aims at solving one of the technical problems in the related art at least to some extent.

[0006] Therefore, the purpose of the utility model is to provide a current measuring device of low voltage circuit, which adopts a high-precision voltmeter and an electronic load, changes the current value of the electronic load, measures the pressure difference of the series-connected magnetic beads FB1, and calculates the accurate current value by using the change amount of the pressure difference and the change amount of the load current.

[0007] To achieve the above purpose, the utility model provides a current measuring device of low voltage circuit, which comprises a power supply circuit, a load circuit, a series-connected magnetic bead, a voltmeter and an electronic load, wherein one end of the series-connected magnetic bead is electrically connected to the power supply circuit; the other end of the series-connected magnetic bead is electrically connected to one end of the load circuit; the negative terminal of the voltmeter is electrically connected to point A at one end of the series-connected magnetic bead; the positive terminal of the voltmeter is electrically connected to point B at the other end of the series-connected magnetic bead; the positive terminal of the electronic load is electrically connected to point B at the other end of the load circuit; and the negative terminal of the electronic load is electrically connected to point C at one end of the load circuit.

[0008] The current measuring device of low voltage circuit of the utility model adopts a high-precision voltmeter and an electronic load, changes the current value of the electronic load, measures the pressure difference of the series-connected magnetic beads FB1, and calculates the accurate current value by using the change amount of the pressure difference and the change amount of the load current.

[0009] In addition, the current measuring device of low voltage circuit proposed by the application can have the following additional technical features:

[0010] Specifically, the power supply circuit is a 1.375V power supply.

[0011] Specifically, the series magnetic bead resistance unit is milliohm, and the voltage unit is millivolt.

[0012] Specifically, the other end of the load circuit and the negative electrode end of the electronic load are grounded respectively.

[0013] Specifically, the other end of the series magnetic bead is connected with the other end of the load circuit, the negative electrode end of the voltmeter and the positive electrode end of the electronic load respectively.

[0014] The additional aspects and advantages of the present application will be partially given in the following description, and some will become apparent from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1 The current measurement circuit diagram of the present application. DETAILED DESCRIPTION

[0017] The embodiments of the present application will be described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application. On the contrary, the embodiments of the present application include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.

[0018] The current measurement device of the low-voltage circuit of the embodiment of the present application will be described below in conjunction with the accompanying drawings.

[0019] As Figure 1 shown, the current measurement device of the low-voltage circuit of the embodiment of the present application includes a power supply circuit, a load circuit, a series magnetic bead, a voltmeter and an electronic load, wherein one end of the series magnetic bead is electrically connected to the power supply circuit; the other end of the series magnetic bead is electrically connected to one end of the load circuit; the negative electrode end of the voltmeter is electrically connected to point A at one end of the series magnetic bead; the positive electrode end of the voltmeter is electrically connected to point B at the other end of the series magnetic bead; the positive electrode end of the electronic load is electrically connected to point B at the other end of the load circuit; and the negative electrode end of the electronic load is electrically connected to point C at one end of the load circuit.

[0020] In an embodiment of the present application, as Figure 1 shown, the power supply circuit is a 1.375V power supply.

[0021] In an embodiment of the present application, asFigure 1 As shown, the series magnetic bead resistance unit is milliohm, and the voltage target unit is millivolt.

[0022] In an embodiment of the present application, as shown in Figure 1 As shown, the other end of the load circuit and the negative electrode end of the electronic load are grounded respectively.

[0023] In an embodiment of the present application, as shown in Figure 1 As shown, the other end of the series magnetic bead is connected with the other end of the load circuit, the negative electrode end of the voltmeter and the positive electrode end of the electronic load respectively.

[0024] Embodiment:

[0025] The measured unit is started, the working mode is set, the voltage drop of the series magnetic bead (FB1) in the series circuit is measured by a high-precision voltmeter, and is recorded as V0, (because the magnetic bead resistance is small, and is in the order of milliohm, so the voltage unit is millivolt)

[0026] The electronic load is set to 250mA, the voltage drop of FB1 is measured, and is recorded as V1,

[0027] The resistance value of the series magnetic bead (FB1) is calculated: R1=(V1-V0) / 250;

[0028] The electronic load is set to 500mA, the voltage drop of FB1 is measured, and is recorded as V2

[0029] The resistance value of the series magnetic bead (FB1) is calculated: R2=(V2-V0) / 500;

[0030] The electronic load is set to 750mA, the voltage drop of FB1 is measured, and is recorded as V3

[0031] The resistance value of the series magnetic bead (FB1) is calculated: R3=(V3-V0) / 750;

[0032] The electronic load is set to 1000mA, the voltage drop of FB1 is measured, and is recorded as V4

[0033] The resistance value of the series magnetic bead (FB1) is calculated: R4=(V4-V0) / 1000;

[0034] The average value of four different loads is recorded as: RFB1=(R1+R2+R3+R4) / 4; (error reduction)

[0035] Then the actual working current is: I=V0 / RFB1 (mA)

[0036] The following table is a measurement and calculation value in the actual circuit:

[0037]

[0038] In summary, in actual low-voltage high-current circuits, a 0-ohm resistor or a magnetic bead is generally connected in series, and these internal resistances are small (less than 50 mΩ), and accurate current values can be measured and calculated through the above method.

[0039] In summary, the current measurement device of the low-voltage circuit of the embodiments of the present application uses a high-precision voltmeter and an electronic load, changes the current value of the electronic load, measures the pressure difference of the connected magnetic bead FB1, and obtains accurate current values through calculation by using the change amount of the pressure difference and the change amount of the load current.

[0040] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and deformations to the above embodiments within the scope of the present application.

Claims

1. A current measuring device for a low voltage circuit, characterized by The device comprises a power supply circuit, a load circuit, a series magnetic bead, a voltmeter and an electronic load, wherein, one end of the series magnetic bead is electrically connected to the power supply circuit; the other end of the series magnetic bead is electrically connected to one end of the load circuit; the negative terminal of the voltmeter is electrically connected to point A at one end of the series magnetic bead; the positive terminal of the voltmeter is electrically connected to point B at the other end of the series magnetic bead; the positive terminal of the electronic load is electrically connected to point B at the other end of the load circuit; the negative terminal of the electronic load is electrically connected to point C at one end of the load circuit.

2. The current measurement device for low voltage circuits of claim 1, wherein, The power supply circuit is a 1.375V power supply.

3. The current measurement device for low voltage circuits of claim 1, wherein, The resistance unit of the series magnetic bead is milliohm, and the unit of the voltmeter is millivolt.

4. The current measurement device for low voltage circuits of claim 1, wherein, The other end of the load circuit and the negative terminal of the electronic load are grounded.

5. The current measurement device for low voltage circuits of claim 1, wherein, The other end of the series magnetic bead is connected to the other end of the load circuit, the negative terminal of the voltmeter and the positive terminal of the electronic load respectively. The power supply circuit is a 1.375V power supply. The resistance unit of the series magnetic bead is milliohm, and the unit of the voltmeter is millivolt. The other end of the load circuit and the negative terminal of the electronic load are grounded. The other end of the series magnetic bead is connected to the other end of the load circuit, the negative terminal of the voltmeter and the positive terminal of the electronic load respectively.

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