CN219065599U - Current detection circuit - Google Patents
Current detection circuit Download PDFInfo
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- CN219065599U CN219065599U CN202223313753.7U CN202223313753U CN219065599U CN 219065599 U CN219065599 U CN 219065599U CN 202223313753 U CN202223313753 U CN 202223313753U CN 219065599 U CN219065599 U CN 219065599U
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Abstract
The utility model discloses a current detection circuit which comprises a power switch circuit, a filtering voltage-stabilizing protection circuit and a current-voltage conversion circuit, wherein the power switch circuit, the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit are respectively connected with an MCU control chip, the power switch circuit is connected with the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit, the current-voltage conversion circuit is connected with an external power supply, a load or a battery pack, and the external power supply is connected with the load or the battery pack through a switch. The utility model solves the problem that the application of the traditional low-end detection circuit is affected due to common ground, has the characteristics of relatively simple circuit structure and low power consumption function, and has the characteristic of energy conservation in a battery management system.
Description
Technical Field
The utility model relates to the technical field of current detection, in particular to a current detection circuit.
Background
The current detection generally refers to detecting the current flowing through a wire or a certain component, commonly using a series resistor, a transformer and the like to convert a current signal into a voltage signal, and then processing and amplifying the voltage signal for later circuit protection and detection. The current detection generally comprises a low-side detection current circuit and a high-side detection current circuit, wherein the low-side detection current circuit is generally used in the occasion of lower voltage, and the high-side detection current circuit is more applicable. The current common modes are: the current of the low-end detection current circuit is sampled by the series resistor and then goes to the ground, as shown in figure 1; the current sampling resistor of the high-side current detection circuit is connected in series to the high-voltage side as shown in fig. 2. The two detection circuit structures have certain problems:
1. the low-side current sense mode adds an extra loop resistance in the ground loop, and due to the common ground of the sampling resistor and the control system, this type of circuit will be limited in many applications, such as in a Battery Management System (BMS), where this type of current sense circuit will not be used to sense the charging current, as it will affect the voltage of the lowest cell.
2. Because the input voltage of the MCU ADC is limited and the voltage of the high-end detection current circuit is higher, the high-end detection current circuit cannot be directly connected to the ADC pin of the sampling chip, and therefore the voltage dividing resistor network needs to have a larger voltage dividing ratio for voltage reduction before the voltage is reduced. A larger voltage division ratio introduces a relatively larger error while requiring higher resistance accuracy.
3. If the current signal detection circuit adopts operational amplification, the cost is high, and particularly, a large common mode signal is processed in a high-end current detection mode.
Disclosure of Invention
In order to solve the above technical problems, the present utility model provides a current detection circuit.
In order to solve the technical problems, the utility model adopts the following technical scheme:
the current detection circuit comprises a power switch circuit, a filtering voltage-stabilizing protection circuit and a current-voltage conversion circuit, wherein the power switch circuit, the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit are respectively connected with an MCU control chip, the power switch circuit is connected with the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit, the current-voltage conversion circuit is connected with an external power supply, a load or a battery pack, and the external power supply is connected with the load or the battery pack through a switch.
As a further improvement, the MCU control chip is provided with a power supply VDD pin, a control pin, a voltage sampling connection pin and a ground pin GND, the power supply switch circuit is connected with the power supply VDD pin and the control pin in the MUC control chip, the filtering voltage stabilizing protection circuit is connected with the voltage sampling pin in the MCU control chip, and the current-voltage conversion circuit is connected with the ground pin GND in the MUC control chip.
As a further improvement, the power switch circuit comprises a MOS tube Q1, a resistor R1 and a resistor R2, wherein a source electrode of the MOS tube Q1 is connected with a power supply VDD pin on the MCU control chip, a source electrode of the MOS tube Q1 is connected with one end of the resistor R1, the other end of the resistor R1 is connected with a gate electrode of the MOS tube Q1, a gate electrode of the MOS tube Q1 is connected with one end of the resistor R2, and the other end of the resistor R2 is connected with a control pin of the MCU control chip.
As a further improvement, the MOS transistor Q1 is a PMOS transistor Q1.
As a further improvement, the current-voltage conversion circuit comprises a voltage dividing module and a current sampling resistor Rs, one end of the voltage dividing module is connected with the drain electrode of the PMOS tube Q1, the other end of the voltage dividing module is connected with one end of the current sampling resistor Rs, the other end of the current sampling resistor Rs is respectively connected with a load or a battery pack and the ground pin GND of the MCU control chip, and the filtering voltage stabilizing protection circuit is connected with the voltage dividing module in parallel.
As a further improvement, the voltage dividing module comprises a resistor R3 and a resistor R4, one end of the resistor R3 is connected with the drain electrode of the PMOS tube Q1, the other end of the resistor R3 is connected with one end of the resistor R4, and the other end of the resistor R4 is connected with the current sampling resistor Rs.
As a further improvement, the filtering voltage stabilizing protection circuit comprises a voltage stabilizing module and a filtering module, wherein the voltage stabilizing module is connected with the resistor R3 in parallel, and the filtering module is connected with the voltage stabilizing module in parallel.
As a further improvement, the weighing module comprises a zener diode DZ1 and a capacitor C1, wherein one end of the negative electrode of the zener diode DZ1 is connected with the drain electrode of the PMOS transistor Q1, one end of the positive electrode of the zener diode DZ1 is connected with a voltage sampling pin in the MCU control chip, and one end of the positive electrode of the zener diode DZ1 is connected with the resistor R3.
As a further improvement, the filtering module includes a capacitor C1, one end of the capacitor C1 is connected to one end of the negative pole of the zener diode DZ1, and the other end of the capacitor C1 is connected to one end of the positive pole of the zener diode DZ 1.
As a further improvement, the negative electrode of the external power supply is connected with a connecting line of a resistor R3 and a resistor R4 in the current-voltage conversion circuit, the positive electrode of the external power supply is connected with a load or a battery pack through a switch, and the load or the battery pack is connected with a current sampling resistor Rs and grounded.
As a further development, the filter module comprises at least one capacitor C1, the individual capacitors being connected in parallel to one another when there are more than two capacitors C1.
Compared with the prior art, the utility model has the following beneficial technical effects:
1. the problem that the application is affected due to common ground of the traditional low-end detection circuit is solved;
2. the problem of overlarge input common mode signal of the operational amplifier due to the fact that the traditional high-end detection circuit introduces a large voltage division ratio resistor network due to higher voltage is solved;
3. the whole structure is simpler, and the cost is lower;
4. the battery management system has the low power consumption function and the energy saving characteristic.
Drawings
FIG. 1 is a schematic diagram of a prior art low-side current detection circuit;
FIG. 2 is a schematic diagram of a prior art high-side current detection circuit;
fig. 3 is a schematic diagram of the current connection principle in the present utility model.
Detailed Description
Embodiments of the present utility model are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present utility model and are not to be construed as limiting the present utility model.
In the description of the present utility model, it should be understood that if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., the indicated azimuth or positional relationship is based on the azimuth or positional relationship shown in the drawings, it is merely for convenience of description and simplification of the description, and does not indicate or imply that the indicated apparatus or element must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present utility model, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the description of the present utility model, it should be noted that the terms "mounted," "connected," and "coupled" are to be construed broadly, as well as, for example, fixedly coupled, detachably coupled, or integrally coupled, unless otherwise specifically indicated and defined. Either mechanically or electrically. Can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.
Example 1
Referring to fig. 3, a current detection circuit includes a power switch circuit, a filtering voltage-stabilizing protection circuit and a current-voltage conversion circuit, wherein the power switch circuit, the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit are respectively connected with an MCU control chip, the power switch circuit is connected with the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit, the current-voltage conversion circuit is connected with an external power supply, a load or a battery pack, and the external power supply is connected with the load or the battery pack through a switch. An external power supply provides power supply for the load or the battery pack, and normal operation is ensured. The current generated by the load or the battery pack is detected by utilizing the respective functions and the coordination of the power switch circuit, the filtering voltage stabilizing protection circuit and the current-voltage conversion circuit, so that the real-time value of the current can be obtained, and the real-time current of the load or the battery pack can be accurately known to be effectively used for protecting and detecting the following circuit.
The MCU control chip is provided with a power supply VDD pin, a control pin, a voltage sampling connection pin and a grounding pin GND, the power supply switch circuit is connected with the power supply VDD pin and the control pin in the MUC control chip, the filtering voltage stabilizing protection circuit is connected with the voltage sampling pin in the MCU control chip, and the current-voltage conversion circuit is connected with the grounding pin GND in the MUC control chip. For the MCU control chip, the prior known chip is adopted, and various types of circuits such as a current acquisition circuit, a control circuit and the like are preset in the chip, so that various required functions such as analog signal conversion to digital signal, control function, acquisition function and the like are formed, the specific model of the MCU control chip is not particularly limited, and the corresponding functional requirements can be met.
The utility model changes the connection mode of the traditional low-end current detection circuit and the high-end current detection circuit, and realizes connection through the whole circuit formed by combining the power switch circuit, the filtering voltage stabilizing protection circuit and the current-voltage conversion circuit.
The on-off control can be performed by using the power switch circuit, a power supply can be connected to the sampling circuit in the MCU control chip, and the power supply of the sampling circuit can be cut off when the sampling circuit is closed, so that the circuit power consumption is reduced, and the low-power consumption control is realized.
The current-voltage conversion circuit can accurately divide voltage, improves the voltage division precision, and can convert corresponding current signals into voltage signals for the rear end to use.
The filtering voltage stabilizing protection circuit is utilized, the whole common ground connection is not needed, the problem that the application is affected due to the common ground is solved, the application range is improved, the voltage signal output to the rear end for detection is stable, and the rear end circuit can be effectively protected from being damaged.
Example two
Referring to fig. 3, the power switching circuit specifically includes a PMOS transistor Q1, a resistor R1, and a resistor R2, where a source of the PMOS transistor Q1 is connected to a power supply VDD pin on the MCU control chip, a source of the MOS transistor Q1 is connected to one end of the resistor R1, another end of the resistor R1 is connected to a gate of the PMOS transistor Q1, a gate of the PMOS transistor Q1 is connected to one end of the resistor R2, and another end of the resistor R2 is connected to a control pin of the MCU control chip, so as to implement corresponding on-off control.
Corresponding control is realized through the resistors R1 and R2, when the PMOS tube Q1 is opened, a closed circuit is realized, and current can pass through to provide power for a sampling circuit in the MCU control chip through a power supply, so that normal sampling is ensured; when the PMOS tube Q1 is closed, the sampling circuit can be cut off to stop supplying power when the sampling circuit is in an off state, and the whole detection circuit does not need to be supplied with power at the moment, so that the effect of reducing the power consumption of the circuit is achieved. The purpose of convenient energy saving and electricity saving can be realized when the system is in standby.
Example III
Referring to fig. 3, the current-voltage conversion circuit includes a voltage dividing module and a current sampling resistor Rs, one end of the voltage dividing module is connected with the drain electrode of the PMOS transistor Q1, the other end of the voltage dividing module is connected with one end of the current sampling resistor Rs, the other end of the current sampling resistor Rs is connected with the ground pin GND of the load or the battery pack and the MCU control chip, and the filtering voltage stabilizing protection circuit is connected in parallel with the voltage dividing module. The voltage dividing module comprises a resistor R3 and a resistor R4, one end of the resistor R3 is connected with the drain electrode of the PMOS tube Q1, the other end of the resistor R3 is connected with one end of the resistor R4, and the other end of the resistor R4 is connected with a current sampling resistor Rs. That is, the resistor R3 and the resistor R4 are connected in series, and the voltage division function is achieved through the connection of the resistor R3 and the resistor R4, the current signal on the current sampling resistor Rs is converted into the voltage signal for the rear end, the current sampling resistor is connected with an external load or a battery pack, and the current can be sampled through the current sampling resistor. The voltage is divided by utilizing the series connection of the resistor R3 and the resistor R4, namely, the voltage is respectively stepped down after passing through the resistor R3 and the resistor R4, so that the problems of precision and overlarge operational amplifier input common mode signals caused by the fact that the traditional high-end detection circuit introduces a large voltage division ratio resistor network due to higher voltage are solved.
The filtering voltage stabilizing protection circuit comprises a voltage stabilizing module and a filtering module, wherein the voltage stabilizing module is connected with the resistor R3 in parallel, and the filtering module is connected with the voltage stabilizing module in parallel.
The weighing module comprises a zener diode DZ1 and a capacitor C1, wherein one end of the negative electrode of the zener diode DZ1 is connected with the drain electrode of the PMOS tube Q1, one end of the positive electrode of the zener diode DZ1 is connected with a voltage sampling pin in the MCU control chip, and one end of the positive electrode of the zener diode DZ1 is connected with a resistor R3. The filtering module comprises a capacitor C1, one end of the capacitor C1 is connected with one end of the negative electrode of the zener diode DZ1, and the other end of the capacitor C1 is connected with one end of the positive electrode of the zener diode DZ 1.
The capacitor C1 plays a role in filtering, and the voltage is filtered, so that a voltage signal output to the rear end for detection is stable. The zener diode DZ1 clamps the voltage division value on the resistor R3, so that the range of the back-end output voltage is controlled in a proper range to facilitate the back-end detection and protect the back-end circuit from damage. The zener diode DZ1 plays a role in stabilizing voltage, so that the problem of excessive jitter of the voltage is avoided.
In addition, in the voltage dividing module, the present embodiment shows that two resistors, namely, the resistor R3 and the resistor R4, are connected in series, and if necessary, other numbers of resistors may be provided, so that the respective resistors are connected in series to form a voltage dividing effect. For the filtering module, the capacitor C1 is adopted in the embodiment, two capacitors or other numbers can be set according to actual needs, and the capacitors are connected in parallel to form the filtering module together, so that the filtering function is achieved, and the voltage signals are balanced.
The values of the resistors and the capacitors can be flexibly selected, flexibly set according to the scene and the use environment, and different types can be formed through the selection of different values so as to meet the use requirements of various groups.
In addition, for a load or a battery pack, which is a specific detection object, the battery pack may be a battery management system, for which output current is detected, an external power supply supplies power to the load or the battery pack, and is controlled by a switch, i.e., turned on or off. Accurate control can be achieved by accurately detecting the real-time circulating current of the load or the battery pack. For the load, there may be various types of application appliances.
According to the utility model, through the combination of the power switch circuit, the filtering voltage stabilizing protection circuit and the current-voltage conversion circuit, the whole connection is convenient, the structure is simplified, and the current signal can be accurately measured. And by on-off control, the purpose of basically zero power consumption is realized in standby.
In specific measurement, referring to fig. 3, the current I flowing out of the load is the current to be detected, and the real-time value of the current I to be detected is calculated to obtain the voltage value between the resistor R4 and the current sampling resistor Rs, and then the voltage at the drain output end of the PMOS transistor Q1 and the voltage at the capacitor C1 are obtained, so that the current I can be calculated according to each value. Specifically, the method can be calculated according to the following formula:
and taking GND as a 0V reference point, taking the ADC reference voltage of the MCU as Vref, the resolution N bits of the ADC, and taking the sampling value of the MCU ADC as N.
U rs ＝0-IRs＝-IRs
U vs ＝U vdd
The current I obtained by the formulas (1) and (2) is as follows:
through the calculation, the real-time value of the current I can be obtained, and reference data can be provided for the rear end.
It should be noted that, the foregoing is only a preferred embodiment of the present utility model, and the present utility model is not limited to the foregoing embodiment, but it should be understood that although the present utility model has been described in detail with reference to the embodiment, it is possible for those skilled in the art to make modifications to the technical solutions described in the foregoing embodiment, or to make equivalent substitutions for some technical features thereof, but any modifications, equivalent substitutions, improvements and the like within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.
Claims (10)
1. The current detection circuit is characterized by comprising a power switch circuit, a filtering voltage-stabilizing protection circuit and a current-voltage conversion circuit, wherein the power switch circuit, the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit are respectively connected with an MCU control chip, the power switch circuit is connected with the filtering voltage-stabilizing protection circuit and the current-voltage conversion circuit, the current-voltage conversion circuit is connected with an external power supply, a load or a battery pack, and the external power supply is connected with the load or the battery pack through a switch.
2. The current detection circuit according to claim 1, wherein the MCU control chip has a power supply VDD pin, a control pin, a voltage sampling connection pin, and a ground pin GND, the power supply switch circuit is connected to the power supply VDD pin and the control pin in the MUC control chip, the filter voltage stabilizing protection circuit is connected to the voltage sampling pin in the MCU control chip, and the current-voltage conversion circuit is connected to the ground pin GND in the MUC control chip.
3. The current detection circuit according to claim 2, wherein the power switching circuit comprises a MOS transistor Q1, a resistor R1 and a resistor R2, a source electrode of the MOS transistor Q1 is connected to a power supply VDD pin on the MCU control chip, a source electrode of the MOS transistor Q1 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to a gate electrode of the MOS transistor Q1, a gate electrode of the MOS transistor Q1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to a control pin of the MCU control chip.
4. The current detection circuit of claim 3, wherein the MOS transistor Q1 is a PMOS transistor Q1.
5. The current detection circuit according to claim 4, wherein the current-voltage conversion circuit comprises a voltage division module and a current sampling resistor Rs, one end of the voltage division module is connected with the drain electrode of the PMOS transistor Q1, the other end of the voltage division module is connected with one end of the current sampling resistor Rs, the other end of the current sampling resistor Rs is connected with the ground pin GND of the load or the battery pack and the MCU control chip respectively, and the filtering voltage stabilizing protection circuit is connected in parallel with the voltage division module.
6. The current detecting circuit according to claim 5, wherein the voltage dividing module comprises a resistor R3 and a resistor R4, one end of the resistor R3 is connected with the drain of the PMOS transistor Q1, the other end of the resistor R3 is connected with one end of the resistor R4, and the other end of the resistor R4 is connected with the current sampling resistor Rs.
7. The current detection circuit of claim 6, wherein the filtering voltage stabilizing protection circuit comprises a voltage stabilizing module and a filtering module, the voltage stabilizing module is connected in parallel with the resistor R3, and the filtering module is connected in parallel with the voltage stabilizing module.
8. The current detecting circuit according to claim 7, wherein the voltage stabilizing module comprises a zener diode DZ1, wherein a negative terminal of the zener diode DZ1 is connected to the drain of the PMOS transistor Q1, a positive terminal of the zener diode DZ1 is connected to the voltage sampling pin in the MCU control chip, and a positive terminal of the zener diode DZ1 is connected to the resistor R3.
9. The current detection circuit according to claim 8, wherein the filter module includes a capacitor C1, one end of the capacitor C1 is connected to a negative end of the zener diode DZ1, and the other end of the capacitor C1 is connected to a positive end of the zener diode DZ 1.
10. The current detection circuit according to claim 9, wherein the negative electrode of the external power supply is connected to a connection line of a resistor R3 and a resistor R4 in the current-voltage conversion circuit, the positive electrode of the external power supply is connected to a load or a battery pack through a switch, and the load or the battery pack is connected to the current sampling resistor Rs and grounded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223313753.7U CN219065599U (en) | 2022-12-08 | 2022-12-08 | Current detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223313753.7U CN219065599U (en) | 2022-12-08 | 2022-12-08 | Current detection circuit |
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| Publication Number | Publication Date |
|---|---|
| CN219065599U true CN219065599U (en) | 2023-05-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202223313753.7U Active CN219065599U (en) | 2022-12-08 | 2022-12-08 | Current detection circuit |
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| CN (1) | CN219065599U (en) |
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- 2022-12-08 CN CN202223313753.7U patent/CN219065599U/en active Active
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