Low-current acquisition circuit and device

Abstract

The utility model relates to the technical field of current acquisition, in particular to a low-current acquisition circuit and device, which comprises a voltage amplification module, the positive input end of the voltage amplification module is connected with a first sampling point, the negative input end of the voltage amplification module is connected with a second sampling point, and a sampling resistor is connected in series between the first sampling point and the second sampling point; the output end of the voltage amplification module is connected with the controller and used for amplifying the sampling voltage at the two ends of the sampling resistor and then outputting the sampling voltage to the controller to obtain a sampling voltage value, and the controller determines a current value according to the sampling voltage value and the resistance value of the sampling resistor; one end of the voltage pull-up module is connected with an external direct current signal source, the other end of the voltage pull-up module is connected with the positive input end of the voltage amplification module, and the voltage pull-up module is used for pulling up the potential of the positive input end if the potential of the first sampling point is smaller than that of the second sampling point so as to ensure that the potential of the positive input end is larger than that of the negative input end. According to the application, the beneficial effect of collecting small current can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of current collection, and in particular to a small current collection circuit and device. Background Art

[0002] In BMS (Battery Management System), AFE (Analog Front End) is usually used to collect current, but the current detection circuits on the market are all large current sampling circuits, which cannot detect small currents. For example, for currents below 10A, small current discharge cannot be detected, and the detection result is 0A. BMS does not think that charging and discharging are in progress, so the battery protection function is not started normally, which may cause current drain or overcharging, and battery damage. It can be seen that how to avoid the above situation and collect small currents is a technical problem that needs to be solved urgently. Utility Model Content

[0003] The purpose of the present application is to provide a small current collection circuit and device, which can achieve the beneficial effect of collecting small currents.

[0004] The first aspect of the present application provides a small current collection circuit and device, including:

[0005] A voltage amplification module, wherein the positive input end of the voltage amplification module is connected to a first sampling point, the negative input end of the voltage amplification module is connected to a second sampling point, a sampling resistor is connected in series between the first sampling point and the second sampling point, and the output end of the voltage amplification module is connected to an external controller, and is used to amplify the sampling voltage across the sampling resistor and output it to the controller to obtain a sampling voltage value, and the controller determines a current value according to the sampling voltage value and the resistance value of the sampling resistor;

[0006] A voltage pull-up module, one end of which is connected to an external DC signal source, and the other end is connected to the positive input terminal of the voltage amplification module, and is used to pull up the potential of the positive input terminal if the potential of the first sampling point is less than the potential of the second sampling point, so as to ensure that the potential of the positive input terminal is greater than the potential of the negative input terminal.

[0007] By adopting the above technical solution, the voltage amplification module includes two input terminals, namely a positive input terminal and a negative input terminal, which are connected to both ends of the sampling resistor to obtain the potentials at both ends of the sampling resistor (i.e., the potential of the first sampling point and the potential of the second sampling point). If the potential of the first sampling point is greater than the potential of the second sampling point, the voltage difference between the two potentials is amplified and then output to the controller after amplification to obtain the sampling voltage value. According to the resistance value of the sampling resistor and the sampling voltage value, the current value of the small current can be calculated; if the potential of the first sampling point is less than the potential of the second sampling point, the potential of the first sampling point is lifted by the voltage boosting module to ensure that the potential of the first sampling point is greater than the potential of the second sampling point, so as to ensure that the output is a positive voltage, which is convenient for the controller to receive the sampling voltage value. In summary, the present application can collect small currents and can also ensure a positive voltage output through the voltage boosting module (the controller cannot receive negative voltages), thereby further ensuring the reliability of small current collection.

[0008] Optionally, the voltage amplification module includes an operational amplifier, a first resistor, and a second resistor;

[0009] The positive input terminal of the operational amplifier is connected to one end of the first resistor, and the other end of the first resistor is connected to one end of the sampling resistor;

[0010] The negative input terminal of the operational amplifier is connected to one end of the second resistor, and the other end of the second resistor is connected to the other end of the sampling resistor;

[0011] The output terminal of the operational amplifier is connected to the controller.

[0012] By adopting the above technical solution, the positive input terminal samples the potential at one end of the sampling resistor through the first resistor, and the negative input terminal samples the potential at the other end of the sampling resistor through the second resistor. The potential of the positive input terminal should be greater than the potential of the negative input terminal, and a positive voltage is output to the controller after proportional amplification. The controller can obtain the current value based on the resistance value of the sampling resistor and the received sampling voltage value.

[0013] Optionally, the voltage amplification module further includes a third resistor;

[0014] One end of the third resistor is connected to the output terminal of the operational amplifier, and the other end is connected to the connection between the second resistor and the negative input terminal.

[0015] By adopting the above technical solution, the third resistor is connected in parallel between the output terminal and the negative input terminal of the operational amplifier. Based on the resistance values of the first resistor and the third resistor, the amplification factor of the operational amplifier can be adjusted.

[0016] Optionally, the voltage amplification module further includes a first capacitor;

[0017] One end of the first capacitor is connected to the connection point of the first resistor and the non-inverting input terminal;

[0018] The other end of the first capacitor is connected to the connection point of the second resistor and the inverting input terminal.

[0019] By adopting the above technical solution, the first capacitor is connected between the non-inverting input terminal and the inverting input terminal to resist interference and suppress noise, thereby improving the stability of the signal.

[0020] Optionally, the voltage amplification module further includes a voltage stabilizing diode;

[0021] One end of the voltage stabilizing diode is connected to the connection point of the first resistor and the non-inverting input terminal;

[0022] The other end of the voltage stabilizing diode is connected to the connection point of the second resistor and the inverting input terminal.

[0023] By adopting the above technical solution, the potentials of the non-inverting input terminal and the inverting input terminal are clamped by the voltage stabilizing diode, thereby ensuring voltage stability and improving the reliability of current acquisition.

[0024] Optionally, the voltage amplification module further includes a second capacitor;

[0025] One end of the second capacitor is connected to the output terminal of the operational amplifier, and the other end is grounded.

[0026] By adopting the above technical solution, the second capacitor is grounded to perform ripple processing on the voltage output by the operational amplifier, so as to avoid interference signals from entering the controller, thereby ensuring the reliability of the sampled voltage value and further improving the accuracy of small current sampling calculation.

[0027] Optionally, the voltage boosting module includes a follower, a fourth resistor, a fifth resistor, and a sixth resistor;

[0028] One end of the fourth resistor is connected to the DC signal source, and the other end is connected to the input terminal of the follower and one end of the fifth resistor, and the other end of the fifth resistor is grounded;

[0029] The output terminal of the follower is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the connection point of the first resistor and the non-inverting input terminal.

[0030] By adopting the above technical solution, if the potential of the non-inverting input terminal is lower than that of the inverting input terminal, the potential of the non-inverting input terminal is raised by the follower to ensure that the voltage of the non-inverting input terminal is greater than that of the inverting input terminal, so that a positive value is output regardless of whether the input terminal is a charging current or a discharging current (the current direction is opposite during charging and discharging).

[0031] In the second aspect of the present application, a small current acquisition device is provided, which is equipped with the above small current acquisition circuit.

[0032] In summary, the beneficial effects of the present application are as follows:

[0033] The voltage amplification module includes two input terminals, a positive input terminal and a negative input terminal, which are connected to both ends of the sampling resistor to obtain the potentials at both ends of the sampling resistor (i.e., the potential of the first sampling point and the potential of the second sampling point). If the potential of the first sampling point is greater than that of the second sampling point, the voltage difference between the two potentials is amplified and then output to the controller after amplification to obtain the sampling voltage value. The current value of the small current can be calculated according to the resistance value of the sampling resistor and the sampling voltage value; if the potential of the first sampling point is less than that of the second sampling point, the potential of the first sampling point is raised by the voltage boosting module to ensure that the potential of the first sampling point is greater than that of the second sampling point, so as to ensure that the output is a positive voltage, which is convenient for the controller to receive the sampling voltage value. In summary, the present application can collect small currents, and can also ensure a positive voltage output through the voltage boosting module (the controller cannot receive negative voltages), thereby further ensuring the reliability of small current collection. Description of the Drawings

[0034] Figure 1 is a module connection diagram of the small current acquisition circuit provided by the embodiment of the present application;

[0035] Figure 2 is a circuit schematic diagram of the small current acquisition circuit provided by the embodiment of the present application. Detailed Embodiments

[0036] The following embodiments will help those skilled in the art to further understand the role of the present application, but do not limit the present application in any form. It should be noted that those of ordinary skill in the art can make several deformations and improvements without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0037] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0038] It should be understood that when used in the specification and appended claims of the present application, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0039] It should also be understood that the term "and / or" used in the specification and appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0040] In addition, in the description of the specification and appended claims of the present application, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0041] The reference to "one embodiment" or "some embodiments" etc. described in the specification of the present application means that a specific feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having", and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0042] The present application will be further described in detail below with reference to the accompanying drawings.

[0043] Referring to Figure 1 , Figure 1 is a module connection diagram of the small current acquisition circuit provided by the embodiment of the present application, including a voltage amplification module 1 and a voltage boost module 2. Specific descriptions of each module are as follows:

[0044] Regarding the voltage amplification module 1: The positive input terminal of the voltage amplification module 1 is connected to the first sampling point RS1, the negative input terminal of the voltage amplification module 1 is connected to the second sampling point RS2, a sampling resistor is connected in series between the first sampling point RS1 and the second sampling point RS2, and the output terminal of the voltage amplification module 1 is connected to an external controller, which is used to amplify the sampling voltage across the sampling resistor and output it to the controller to obtain a sampling voltage value, and the controller determines the current value according to the sampling voltage value and the resistance value of the sampling resistor.

[0045] Specifically, please refer to Figure 2 , Figure 2 which is the circuit schematic diagram of the small current acquisition circuit provided by the embodiment of the present application. The following is a specific description in combination with the specific circuit:

[0046] The voltage amplification module 1 includes an operational amplifier U1, a first resistor R1, and a second resistor R2;

[0047] The non-inverting input terminal of the operational amplifier U1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to one end of the sampling resistor;

[0048] The inverting input terminal of the operational amplifier U1 is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the other end of the sampling resistor;

[0049] The output terminal of the operational amplifier U1 is connected to the controller.

[0050] Specifically, the non-inverting input terminal samples the potential of one end of the sampling resistor through the first resistor R1, the inverting input terminal samples the other end of the sampling resistor through the second resistor R2, the potential of the non-inverting input terminal should be greater than the potential of the inverting input terminal, and a positive voltage is output to the controller after proportional amplification, that is, output to the Current ADC port. The controller can obtain the current value based on the resistance value of the sampling resistor and the received sampling voltage value.

[0051] Optionally, the voltage amplification module 1 further includes a third resistor R3;

[0052] One end of the third resistor R3 is connected to the output terminal of the operational amplifier U1, and the other end is connected to the connection between the second resistor R2 and the inverting input terminal.

[0053] Specifically, the third resistor R3 is connected in parallel between the output terminal and the inverting input terminal of the operational amplifier U1. Based on the resistance values of the first resistor R1 and the third resistor R3, the amplification factor of the operational amplifier U1 can be adjusted.

[0054] Optionally, the voltage amplification module 1 further includes a first capacitor C1;

[0055] One end of the first capacitor C1 is connected to the connection point of the first resistor R1 and the non-inverting input terminal;

[0056] The other end of the first capacitor C1 is connected to the connection point of the second resistor R2 and the inverting input terminal.

[0057] By adopting the above technical solution, the first capacitor C1 is connected between the non-inverting input terminal and the inverting input terminal to resist interference and suppress noise, thereby improving the stability of the signal.

[0058] Optionally, the voltage amplification module 1 further includes a zener diode Z1;

[0059] One end of the zener diode Z1 is connected to the connection point of the first resistor R1 and the non-inverting input terminal;

[0060] The other end of the zener diode Z1 is connected to the connection point of the second resistor R2 and the inverting input terminal.

[0061] Specifically, the potentials of the non-inverting input terminal and the inverting input terminal are clamped by the zener diode Z1, thereby ensuring voltage stability and improving the reliability of current acquisition.

[0062] Optionally, the voltage amplification module 1 further includes a second capacitor C2;

[0063] One end of the second capacitor C2 is connected to the output terminal of the operational amplifier U1, and the other end is grounded.

[0064] Specifically, the second capacitor C2 is grounded to perform ripple processing on the voltage output by the operational amplifier U1, so as to avoid interference signals from entering the controller, thereby ensuring the reliability of the sampled voltage value and further improving the accuracy of small current sampling calculation.

[0065] Regarding the voltage boosting module 2: One end of the voltage boosting module 2 is connected to an external DC signal source, and the other end is connected to the positive input terminal of the voltage amplification module 1, and is used to boost the potential of the positive input terminal if the potential of the first sampling point RS1 is less than the potential of the second sampling point RS2, so as to ensure that the potential of the positive input terminal is greater than the potential of the negative input terminal.

[0066] Specifically, please refer to Figure 2 , the voltage boosting module 2 includes a follower U2, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6;

[0067] One end of the fourth resistor R4 is connected to the DC signal source, and the other end is connected to the input end of the follower U2 and one end of the fifth resistor R5. The other end of the fifth resistor R5 is grounded;

[0068] The output end of the follower U2 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is connected to the connection point of the first resistor R1 and the non-inverting input end.

[0069] Specifically, if the potential of the non-inverting input end is lower than that of the inverting input end, the potential of the non-inverting input end is raised through the follower U2 to ensure that the voltage of the non-inverting input end is greater than that of the inverting input end, so that a positive value is output regardless of whether the input end is a charging current or a discharging current (the current direction is opposite during charging and discharging).

[0070] More specifically, in this embodiment, the DC signal source is 3.3V. Voltage division is performed through the fourth resistor R4 and the fifth resistor R5. The fourth resistor R4 and the fifth resistor R5 have the same resistance value, that is, a voltage value of 3.3 / 2V is obtained by voltage division at the output end of the follower U2. The voltage is output to the non-inverting input end along with the follower U2, so as to ensure that the potential of the non-inverting input end is always higher than that of the inverting input end, so that the operational amplifier U1 always outputs a positive voltage for the controller to receive. In the embodiment of the present application, the controller can be a single-chip microcomputer.

[0071] The second aspect of the present application provides a small current acquisition device loaded with the above small current acquisition circuit.

[0072] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A small current collection circuit, characterized in that: include: A voltage amplification module, wherein the positive input end of the voltage amplification module is connected to a first sampling point, the negative input end of the voltage amplification module is connected to a second sampling point, a sampling resistor is connected in series between the first sampling point and the second sampling point, and the output end of the voltage amplification module is connected to an external controller, and is used to amplify the sampling voltage across the sampling resistor and output it to the controller to obtain a sampling voltage value, and the controller determines a current value according to the sampling voltage value and the resistance value of the sampling resistor; A voltage pull-up module, one end of which is connected to an external DC signal source, and the other end is connected to the positive input terminal of the voltage amplification module, and is used to pull up the potential of the positive input terminal if the potential of the first sampling point is less than the potential of the second sampling point, so as to ensure that the potential of the positive input terminal is greater than the potential of the negative input terminal.

2. The low current acquisition circuit according to claim 1, characterized in that: The voltage amplification module includes an operational amplifier, a first resistor and a second resistor; The non-inverting input terminal of the operational amplifier is connected to one end of the first resistor, and the other end of the first resistor is connected to one end of the sampling resistor; The inverting input terminal of the operational amplifier is connected to one end of the second resistor, and the other end of the second resistor is connected to the other end of the sampling resistor; The output end of the operational amplifier is connected to the controller.

3. The low current acquisition circuit according to claim 2, characterized in that: The voltage amplification module also includes a third resistor; One end of the third resistor is connected to the output end of the operational amplifier, and the other end is connected to the connection point between the second resistor and the inverting input end.

4. The low current acquisition circuit according to claim 2, characterized in that: The voltage amplification module also includes a first capacitor; One end of the first capacitor is connected to a connection point between the first resistor and the non-inverting input terminal; The other end of the first capacitor is connected to a connection point between the second resistor and the inverting input terminal.

5. The low current acquisition circuit according to claim 2, characterized in that: The voltage amplification module also includes a voltage regulator tube; One end of the voltage regulator tube is connected to the connection point between the first resistor and the non-phase input end; The other end of the voltage regulator is connected to the connection point of the second resistor and the inverting input end.

6. The low current acquisition circuit according to claim 2, characterized in that: The voltage amplification module also includes a second capacitor; One end of the second capacitor is connected to the output end of the operational amplifier, and the other end is grounded.

7. The low current acquisition circuit according to claim 2, characterized in that: The voltage pull-up module includes a follower, a fourth resistor, a fifth resistor, and a sixth resistor; One end of the fourth resistor is connected to the DC signal source, and the other end is connected to the input end of the follower and one end of the fifth resistor, and the other end of the fifth resistor is grounded; The output end of the follower is connected to one end of the sixth resistor, and the other end of the sixth resistor is connected to the connection point of the first resistor and the non-phase input end.

8. A small current collection device, characterized in that: The device is equipped with a small current collection circuit as described in any one of claims 1 to 7.

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