Battery internal resistance detection circuit

Abstract

The embodiment of the utility model provides a battery internal resistance detection circuit, and the circuit comprises a voltage sampling circuit which is connected with the positive electrode of a to-be-detected battery and outputs a battery sampling voltage; the switch unit comprises a first end, a second end and a third end for controlling on-off of the first end and the second end; the first end is coupled with the anode of the to-be-detected battery; the current sampling circuit comprises a sampling resistor, one end of the sampling resistor is coupled with the switch unit, and the other end of the sampling resistor is grounded; the sampling resistor flows through the battery output current when the switch unit is switched on; the differential amplification circuit comprises a first input end and a second input end which are coupled to the two ends of the sampling resistor respectively; the differential amplification circuit samples the voltage difference between the two ends of the sampling resistor to obtain the sampling voltage of the sampling resistor. By accurately measuring the voltage and current of the battery, the internal resistance of the battery can be accurately calculated, and the health condition and performance of the battery are reflected.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of battery detection, and particularly relates to a battery internal resistance detection circuit. BACKGROUND

[0002] In modern electronic devices and power systems, batteries serve as important energy storage and power supply devices, and their performance is directly related to the reliability and efficiency of the system. In order to ensure the safe use and optimal management of the battery, accurately measuring the internal resistance of the battery is a key technology. Changes in the internal resistance of the battery can reflect the health status, aging degree and charge-discharge characteristics of the battery, so real-time monitoring of the internal resistance of the battery is of great significance. SUMMARY

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present disclosure is to provide a battery internal resistance detection circuit to solve the problems in the related art.

[0004] The first aspect of the present disclosure provides a battery internal resistance detection circuit, comprising:

[0005] a voltage sampling circuit connected to the positive electrode of the battery to be detected and outputting a battery sampling voltage;

[0006] a switch unit including a first end, a second end, and a third end for controlling the on-off of the first end and the second end; the first end is coupled to the positive electrode of the battery to be detected;

[0007] a current sampling circuit, comprising:

[0008] a sampling resistor, one end of the sampling resistor being coupled to the switch unit, and the other end of the sampling resistor being grounded; the sampling resistor flows through the battery output current when the switch unit is turned on;

[0009] a differential amplifier circuit, comprising a first input end and a second input end coupled to both ends of the sampling resistor respectively; the differential amplifier circuit samples the voltage difference between both ends of the sampling resistor to obtain a sampling resistor sampling voltage; wherein the ratio of the sampling resistor sampling voltage to the resistance value of the sampling resistor is used to obtain a battery sampling current corresponding to the battery output current, and the ratio of the battery sampling voltage to the battery sampling current is used to obtain the internal resistance of the battery to be detected.

[0010] In an embodiment of the first aspect, the voltage sampling circuit comprises:

[0011] a first resistor, one end of the first resistor being coupled to the positive electrode of the battery to be detected, and the other end of the first resistor being grounded via a second resistor; a voltage dividing point between the first resistor and the second resistor is used to output the battery sampling voltage.

[0012] In an embodiment of the first aspect, the voltage sampling circuit further comprises a first capacitor, one end of the first capacitor is coupled to the voltage dividing point, and the other end of the first capacitor is grounded.

[0013] In an embodiment of the first aspect, the switch unit comprises:

[0014] a switch element, a first end of the switch element is coupled to the positive electrode of the battery to be detected, a second end of the switch element is coupled to the current sampling circuit, and a control end of the switch element is coupled to an external control end via a third resistor, the external control end is used to generate a control signal to control the switch unit to be turned on;

[0015] a fourth resistor, one end of the fourth resistor is coupled to the control end of the switch element and one end of the third resistor, and the other end of the fourth resistor is grounded.

[0016] In an embodiment of the first aspect, the switch element is implemented as one of a MOS tube or a triode.

[0017] In an embodiment of the first aspect, the differential amplification circuit comprises:

[0018] a differential amplifier, comprising a non-inverting input end, an inverting input end, and a differential output end; the non-inverting input end is coupled to one end of the sampling resistor via a biasing circuit;

[0019] an input resistor, one end of the input resistor is coupled to the other end of the sampling resistor, and the other end of the input resistor is coupled to the inverting input end;

[0020] a feedback resistor, one end of the feedback resistor is coupled to the inverting input end, and the other end of the feedback resistor is coupled to the differential output end.

[0021] In an embodiment of the first aspect, the biasing circuit comprises:

[0022] a fifth resistor, one end of the fifth resistor is coupled to the switch unit, and the other end of the fifth resistor is coupled to a biasing voltage via a sixth resistor; a voltage dividing point between the fifth resistor and the sixth resistor is coupled to the non-inverting input end.

[0023] In an embodiment of the first aspect, further comprising:

[0024] a seventh resistor, one end of the seventh resistor is coupled to the differential output end, and the other end of the seventh resistor is coupled to an external current sampling end;

[0025] a second capacitor, one end of the second capacitor is coupled to the seventh resistor, and the other end of the second capacitor is grounded.

[0026] In an embodiment of the first aspect, further comprising a third capacitor, one end of which is coupled to the positive input end, and the other end of which is coupled to the negative input end.

[0027] In an embodiment of the first aspect, further comprising a diode arranged in a forward direction between the positive electrode of the battery to be detected and the switch unit.

[0028] Advantages of the present disclosure: By accurately measuring the battery voltage and current, the battery internal resistance can be accurately calculated, reflecting the health status and performance of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A circuit connection schematic diagram of a battery internal resistance detection circuit in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0030] The embodiments of the present disclosure will be described in detail below with specific reference to specific examples. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the messages disclosed in the present disclosure. The present disclosure can also be implemented or applied in different specific embodiments or modules, and various modifications or changes can be made to the details of the present disclosure without departing from the spirit of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0031] The embodiments of the present disclosure will be described in detail below with specific reference to specific examples. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the messages disclosed in the present disclosure. The present disclosure can also be implemented or applied in different specific embodiments or modules, and various modifications or changes can be made to the details of the present disclosure without departing from the spirit of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0032] In the present disclosure, the expressions of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that the specific features, structures, materials or characteristics expressed in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. Moreover, the specific features, structures, materials or characteristics expressed can be combined in any one or a group of embodiments or examples in a suitable manner. In addition, different embodiments or examples expressed in the present disclosure and the features of different embodiments or examples can be combined and combined by those skilled in the art without conflict.

[0033] In addition, the terms "first", "second" are only used for the purpose of expression, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the present disclosure, the meaning of "a group" is two or more, unless otherwise specifically limited.

[0034] For the purpose of clearness of the present disclosure, devices irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar constituent elements throughout the specification.

[0035] Throughout the specification, when it is said that a certain device is "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" in which other elements are interposed therebetween. In addition, when it is said that a certain device "includes" a certain constituent element, other constituent elements are not excluded unless specifically stated to the contrary, but it means that other constituent elements can be further included.

[0036] Although the terms first, second, etc. are used herein to refer to various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first interface and a second interface, etc. are denoted. Also, as used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and / or "including," when used herein, specify the presence of stated features, steps, operations, elements, modules, items, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, modules, items, and / or groups thereof. As used herein, the terms "or" and "and / or" are construed to be inclusive, or mean either one or any combination thereof. Thus, "A, B, or C" or "A, B, and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B, and C." Exceptions to this definition are only present when items, components, elements, or steps are not mutually exclusive from one another in some manner.

[0037] The professional terms used herein are used only to refer to specific embodiments, and are not intended to limit the present disclosure. The singular form used herein, unless the context clearly indicates otherwise, also includes the plural form. The meaning of "include" used in the specification is to specify a certain characteristic, region, integer, step, operation, element, and / or component, and is not to exclude the presence or addition of other characteristics, regions, integers, steps, operations, elements, and / or components.

[0038] Although not differently defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Terms defined in commonly used dictionaries are to be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0039] The change of the battery internal resistance can reflect the health state, aging degree and charge-discharge characteristics of the battery, and therefore it is of great significance to monitor the battery internal resistance in real time.

[0040] In an embodiment of the present disclosure, a battery internal resistance detection circuit is provided, in which the internal resistance of a battery to be detected can be obtained by comparing the ratio of a battery sampling voltage to a battery sampling current, and the battery sampling current can be obtained by a differential amplification circuit.

[0041] In Figure 1 In an embodiment, the battery internal resistance detection circuit comprises:

[0042] a voltage sampling circuit connected to the positive electrode of the battery to be detected and outputting a battery sampling voltage.

[0043] Specifically, in some embodiments, the voltage sampling circuit is configured to sample the battery sampling voltage of the battery to be detected when the switching unit Q1 is turned on and turned off. The voltage sampling circuit can be connected to the positive electrode of the battery to be detected by a voltage sensor or a voltage dividing network to sample the voltage of the battery to be detected.

[0044] Optionally, in Figure 1 In an embodiment, the voltage sampling circuit comprises:

[0045] a first resistor R1, one end of the first resistor R1 being coupled to the positive electrode of the battery to be detected, the other end of the first resistor R1 being grounded via a second resistor R2, and an output end for outputting the battery sampling voltage being led out at a voltage dividing point between the first resistor R1 and the second resistor R2. The second resistor R2 is connected in series with the first resistor R1 to form a voltage dividing network for detecting the voltage of the battery.

[0046] Optionally, the voltage sampling circuit further comprises a first capacitor C1, one end of the first capacitor C1 being coupled to the voltage dividing point, and the other end of the first capacitor C1 being grounded. The first capacitor C1 is configured to filter high-frequency noise, and the selection of the capacitor should consider its capacitance value and the resistance values of the first resistor R1 and the second resistor R2 to ensure good filtering effect without affecting the response speed.

[0047] In Figure 1 In an embodiment, the switching unit Q1 comprises:

[0048] a switching element, a first end of the switching element being coupled to the positive electrode of the battery to be detected, a second end of the switching element being coupled to a current sampling circuit, and a control end of the switching element being coupled to an external control end via a third resistor R3, the external control end being configured to generate a control signal to control the switching unit Q1 to be turned on; optionally, the switching element is implemented as one of a MOS tube or a triode.

[0049] For example, when the external control terminal sends a high level signal, the high level is transmitted to the gate (control terminal) of the MOS tube through the third resistor R3, so that the MOS tube is turned on. At this time, the positive electrode of the battery is connected with the current sampling circuit through the source-drain channel of the MOS tube, forming a current loop. When the external control terminal sends a low level signal, the gate voltage of the MOS tube is not enough to open the MOS tube, so it remains closed, cutting off the connection between the battery and the current sampling circuit. The selection of the MOS tube can be determined according to the actual situation, which is not limited here. Working mode of the transistor as a switching element: for NPN type transistor, when the external control terminal outputs a high enough base voltage, the base voltage is pulled up through the third resistor R3, so that the transistor enters the saturation region, and the current path between the collector and the emitter is turned on. When the external control terminal sends a low level signal, the base current is not enough, the transistor is cut off, and the connection between the battery and the current sampling circuit is cut off. Similarly, the transistor can also be implemented as a PNP type transistor.

[0050] The fourth resistor R4 has one end coupled to the control terminal of the switching element and one end of the third resistor R3, and the other end grounded.

[0051] Specifically, in some embodiments, the third resistor R3 is used to limit the current flowing into the control terminal of the switching element, protecting the switching element from excessive driving current. The fourth resistor R4 is used to provide a stable low level reference for the control terminal of the switching element, ensuring that the switching element is in the off state when there is no external control signal. The fourth resistor R4 also helps to prevent the control terminal from being suspended.

[0052] In Figure 1 In an embodiment, the current sampling circuit comprises:

[0053] The sampling resistor Rs has one end coupled to the switching unit Q1 and the other end grounded. The sampling resistor Rs flows through the battery output current when the switching unit Q1 is turned on. The principle of current sampling for the battery B1 to be detected is specifically explained. It can be seen that, Figure 1When the middle switch unit Q1 is turned on, the positive electrode of the battery to be detected B1 forms a loop with Q1 and a sampling resistor Rs to the ground. When Q1 is turned on, the battery output current flows through the sampling resistor Rs, and according to Ohm's law, a voltage proportional to the current will be generated on the sampling resistor Rs. This voltage can be used to indirectly measure the battery output current by dividing the Rs. The voltage (Vp) at the end of Rs connected to Q1 is close to the voltage of the battery to be detected B1, and the other end of Rs is connected to the ground, so the battery output current can be obtained by dividing the resistance value of Rs with Vp. However, in practice, since the application scenario of this circuit may be consumer electronics products, in order to reduce the heat and improve the user experience, the sampling resistor Rs is usually very small, so the voltage on the sampling resistor Rs is very small. Moreover, directly measuring the voltage across the sampling resistor Rs may be affected by various factors, including temperature drift, power supply fluctuations, etc., resulting in measurement errors.

[0054] To this end, the current sampling circuit further includes a differential amplification circuit, which includes a first input end and a second input end respectively coupled to the two ends of the sampling resistor Rs; the differential amplification circuit samples the voltage difference across the sampling resistor Rs to obtain a sampling resistor sampling voltage; wherein the ratio of the sampling resistor sampling voltage to the resistance value of the sampling resistor Rs is used to obtain a battery sampling current corresponding to the battery output current, and the ratio of the battery sampling voltage to the battery sampling current is used to obtain the internal resistance of the battery to be detected B1.

[0055] The differential amplification circuit can provide high gain to amplify the tiny voltage change to a suitable value for subsequent processing. Specifically, the voltage drop on the sampling resistor Rs is very small, and direct measurement may not be able to obtain sufficient resolution. Through the differential amplification circuit, on the one hand, the tiny voltage can be effectively amplified, thereby ensuring accurate measurement. Moreover, in the actual environment, there are various noise sources such as power supply noise, electromagnetic interference, etc., which may be superimposed on the voltage across the sampling resistor Rs, affecting the measurement accuracy. In addition, the differential amplification circuit has a good common-mode rejection ratio, and by differentiating the voltage across Rs, the noise signals that appear simultaneously at both input ends are eliminated. Since the differential amplification circuit only amplifies the difference between the two input ends, but not the common-mode component, the influence of external noise on the measurement result is greatly reduced, and the signal-to-noise ratio is improved. Therefore, using the differential amplification circuit can accurately sample the voltage difference across the sampling resistor Rs.

[0056] Optionally, the differential amplification circuit includes:

[0057] a differential amplifier U, including a non-inverting input end, a negative phase input end and a differential output end; the non-inverting input end is coupled to one end of the sampling resistor Rs through a bias circuit;

[0058] an input resistor R5, one end of the input resistor R5 being coupled to the other end of the sampling resistor Rs, the other end of the input resistor R5 being coupled to the negative input terminal;

[0059] a feedback resistor R6, one end of the feedback resistor R6 being coupled to the negative input terminal, the other end of the feedback resistor R6 being coupled to the differential output terminal.

[0060] In particular, in some embodiments, the biasing circuit is used to ensure a stable DC level at the positive input terminal of the differential amplifier U, avoiding errors due to input bias current. The biasing circuit can be a simple voltage divider or a constant current source, depending on the application requirements and available components. The input resistor R5 is used to match the input impedance of the differential amplifier U, reducing the impact on the sampling resistor Rs.

[0061] When the switch unit Q1 is turned on, the battery output current flows through the sampling resistor Rs, generating a voltage drop proportional to the current. The voltage across the sampling resistor Rs is coupled to the positive input terminal and the negative input terminal of the differential amplifier U, respectively. The positive input terminal maintains a stable DC level through the biasing circuit, while the negative input terminal receives the voltage at the other end of the sampling resistor Rs through the input resistor R5.

[0062] Optionally, the biasing circuit comprises:

[0063] a fifth resistor R7, one end of the fifth resistor R7 being coupled to the switch unit Q1, the other end of the fifth resistor R7 being coupled to a bias voltage via a sixth resistor R8; a voltage dividing point between the fifth resistor R7 and the sixth resistor R8 being coupled to the positive input terminal.

[0064] In particular, in some embodiments, the fifth resistor R7 and the sixth resistor R8 form a voltage divider, providing a stable DC voltage to the positive input terminal of the differential amplifier U. According to the virtual short virtual open principle of the differential amplifier U, combined with the following formula: ; wherein, Vp is the voltage at the positive input terminal of the differential amplifier U, Vd is the voltage at the differential output terminal of the differential amplifier U, Vg is the voltage at the ground terminal of the sampling resistor Rs, Vb is 0; the voltage at the positive terminal of the sampling resistor Rs connected to the battery to be detected is calculated according to the above formula , and the battery sampling current is obtained according to the resistance value of the sampling resistor Rs, so as to calculate the internal resistance of the battery B1 to be detected.

[0065] Optionally, the battery internal resistance detection circuit further comprises:

[0066] a seventh resistor R9, one end of the seventh resistor R9 is coupled to the differential output end, the other end of the seventh resistor R9 is coupled to an external current sampling end;

[0067] a second capacitor C2, one end of the second capacitor C2 is coupled to the seventh resistor R9, the other end of the second capacitor C2 is grounded. The seventh resistor R9 and the second capacitor C2 form an RC filter network.

[0068] Optionally, the battery internal resistance detection circuit further comprises a third capacitor C3, one end of the third capacitor C3 is coupled to the positive input end, the other end of the third capacitor C3 is coupled to the negative input end, for suppressing common-mode noise. Help stabilize the DC level between the two input terminals.

[0069] Optionally, the battery internal resistance detection circuit further comprises a diode arranged in the positive direction between the positive electrode of the battery to be detected B1 and the switch unit Q1. Prevent reverse current from flowing from the switch unit Q1 to the battery, protect the battery from possible damage. When the switch unit Q1 is turned on, the diode is in a forward bias state, allowing current to flow from the battery to the load. When the switch unit Q1 is turned off, the diode prevents any reverse current from flowing from the load to the battery, protecting the battery from damage.

[0070] The above embodiments are only illustrative of the principles of the present disclosure and its effectiveness, and are not intended to limit the present disclosure. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed by the present disclosure shall be covered by the protection scope of the present disclosure.

Claims

1. A battery internal resistance detection circuit characterized by comprising: The application relates to a battery detection circuit. The battery detection circuit comprises: a voltage sampling circuit connected to the positive pole of a battery to be detected and outputting a battery sampling voltage; a switch unit comprising a first end, a second end and a third end for controlling the on-off of the first end and the second end; the first end is coupled to the positive pole of the battery to be detected; a current sampling circuit comprising: a sampling resistor, one end of the sampling resistor being coupled to the switch unit and the other end of the sampling resistor being grounded; the sampling resistor flows through the battery output current when the switch unit is turned on; 2. The battery internal resistance detection circuit according to claim 1, characterized by, a differential amplifier circuit comprising a first input end and a second input end coupled to both ends of the sampling resistor respectively; the differential amplifier circuit samples the voltage difference between both ends of the sampling resistor to obtain a sampling resistor sampling voltage; wherein the ratio of the sampling resistor sampling voltage to the resistance value of the sampling resistor is used to obtain a battery sampling current corresponding to the battery output current, and the ratio of the battery sampling voltage to the battery sampling current is used to obtain the internal resistance of the battery to be detected. The voltage sampling circuit comprises:

3. The battery internal resistance detection circuit according to claim 2, characterized by, a first resistor, one end of the first resistor being coupled to the positive pole of the battery to be detected, the other end of the first resistor being grounded through a second resistor, and an output end for outputting the battery sampling voltage being led out at a voltage dividing point between the first resistor and the second resistor.

4. The battery internal resistance detection circuit according to claim 1, characterized by The voltage sampling circuit further comprises a first capacitor, one end of the first capacitor being coupled to the voltage dividing point and the other end of the first capacitor being grounded. The switch unit comprises: a switch element, the first end of the switch element being coupled to the positive pole of the battery to be detected, the second end of the switch element being coupled to the current sampling circuit, and the control end of the switch element being coupled to an external control end through a third resistor, the external control end being used to generate a control signal to control the switch unit to be turned on; 5. The battery internal resistance detection circuit according to claim 4, characterized by a fourth resistor, one end of the fourth resistor being coupled to the control end of the switch element and the other end of the third resistor, and the other end of the fourth resistor being grounded.

6. The battery internal resistance detection circuit according to claim 1, wherein The switch element is implemented as one of a MOS tube or a triode. The differential amplifier circuit comprises: a differential amplifier comprising a positive phase input end, a negative phase input end and a differential output end; the positive phase input end being coupled to one end of the sampling resistor through a bias circuit; an input resistor, one end of the input resistor being coupled to the other end of the sampling resistor and the other end of the input resistor being coupled to the negative phase input end; 7. The battery internal resistance detection circuit according to claim 6, wherein a feedback resistor, one end of the feedback resistor being coupled to the negative phase input end and the other end of the feedback resistor being coupled to the differential output end. The bias circuit comprises:

8. The battery internal resistance detection circuit according to claim 6, wherein a fifth resistor, one end of the fifth resistor being coupled to the switch unit and the other end of the fifth resistor being coupled to a bias voltage through a sixth resistor; a voltage dividing point between the fifth resistor and the sixth resistor being coupled to the positive phase input end. Further comprising: a seventh resistor, one end of the seventh resistor being coupled to the differential output end and the other end of the seventh resistor being coupled to an external current sampling end; 9. The battery internal resistance detection circuit according to claim 6, wherein a second capacitor, one end of the second capacitor being coupled to the seventh resistor and the other end of the second capacitor being grounded. Further comprising a third capacitor, one end of the third capacitor being coupled to the positive phase input end and the other end of the third capacitor being coupled to the negative phase input end.

10. The battery internal resistance detection circuit according to claim 1, characterized by, Also included is a diode arranged in forward direction between the positive pole of the battery to be detected and the switching unit.

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