Controllable constant current charging circuit in lithium battery core test

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By designing a controllable constant current charging circuit for lithium battery cell testing, the problem of damage caused by unreasonable voltage in existing technologies has been solved. Constant current charging from the initial stage has been achieved, improving testing safety and protection. This circuit is applicable to various lithium battery cells.

CN223553080UActive Publication Date: 2025-11-14QINGDAO RUIJIE INTELLIGENT INSTR

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Patent Information

Application Number: CN202423112910.7
Authority / Receiving Office: CN · China
Patent Type: Utility models(China)
Current Assignee / Owner
Filing Date: 2024-12-17
Publication Date: 2025-11-14
Estimated Expiration: 2034-12-17

AI Technical Summary

Technical Problem

Existing lithium battery cell testing methods lack controllable constant current charging circuits, which may damage the battery and testing equipment if the charging voltage is unreasonable. Furthermore, conventional solutions often use constant voltage first and then constant current, lacking protection in the initial stage.

Method used

A controllable constant current charging circuit for lithium battery cell testing was designed, including the lithium battery cell under test, a sampling circuit, a voltage feedback control circuit, a current feedback control circuit, a PWM control chip, a half-bridge inverter circuit, and an output power circuit. Constant current charging is achieved through voltage and current feedback control, and it is suitable for various lithium battery cells.

Benefits of technology

It achieves controllable constant current charging from the uA level to the mA level, improving test safety and protection. It is suitable for various lithium battery cells and performs constant current charging from the initial stage.

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Abstract

The utility model belongs to the technical field of lithium battery core testing, and discloses a controllable constant current charging circuit in lithium battery core testing, which comprises a lithium battery core to be tested, a sampling circuit, a voltage feedback control circuit, a current feedback control circuit, a PWM (Pulse Width Modulation) control chip, a half-bridge inverter circuit and an output power circuit, the output end of the tested lithium battery core is connected with the input end of the sampling circuit, and the output end of the sampling circuit is connected with the input end of the voltage feedback control circuit and the input end of the current feedback control circuit. The controllable constant-current charging circuit for lithium battery core measurement can realize controllable constant-current charging from uA level to mA level, is large in adjustable range of constant-current values, and can be suitable for various different types of lithium battery cores; and in the pulse method test of the lithium battery core, constant-current charging is started from the initial stage, so that the safety and protectiveness of the test are improved.

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Description

Technical Field

[0001] This utility model relates to the field of lithium battery cell testing technology, and in particular to a controllable constant current charging circuit for lithium battery cell testing. Background Technology

[0002] The pulse test method is a commonly used measurement method for identifying short circuits or micro-short circuits between the positive and negative electrodes of lithium battery cells. The pulse test consists of three stages: charging, holding voltage, and discharging. During the charging process, if the charging voltage is set improperly, either too high or too low, it may lead to excessive charging current, which can damage the lithium battery cell and potentially damage the related circuitry of the tester. Therefore, a controllable constant current charging circuit is needed to ensure that the battery can be continuously charged under a constant current.

[0003] Currently, there are few circuits suitable for constant current charging of lithium battery cells. Most constant current charging schemes first perform constant voltage charging, and then perform constant current charging after a certain voltage is reached.

[0004] Therefore, how to provide a controllable constant current charging circuit for lithium battery cell testing is an urgent problem to be solved. Utility Model Content

[0005] This utility model provides a controllable constant current charging circuit for lithium battery cell testing to solve the above-mentioned technical problems in the prior art.

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or to describe the scope of protection of these embodiments. Its sole purpose is to present some concepts in a simple form as a prelude to the detailed description that follows.

[0007] According to an embodiment of the present invention, a controllable constant current charging circuit for testing lithium battery cells is provided.

[0008] In one embodiment, the controllable constant current charging circuit in the lithium battery cell test includes: the lithium battery cell under test, a sampling circuit, a voltage feedback control circuit, a current feedback control circuit, a PWM control chip, a half-bridge inverter circuit, and an output power circuit.

[0009] The output terminal of the lithium battery cell under test is connected to the input terminal of the sampling circuit. The output terminal of the sampling circuit is connected to the input terminals of the voltage feedback control circuit and the current feedback control circuit, respectively. The output terminals of the voltage feedback control circuit and the current feedback control circuit are both connected to the input terminal of the PWM control chip. The output terminal of the PWM control chip is connected to the input terminal of the half-bridge inverter circuit. The output terminal of the half-bridge inverter circuit is connected to the input terminal of the output power circuit. The output terminal of the output power circuit is connected to both the lithium battery cell under test and the input terminal of the sampling circuit.

[0010] In one embodiment, the voltage feedback control circuit includes: operational amplifier IC3A, operational amplifier IC3B, resistors R22, R23, R24, R26, R27, R28, R29, R30, diode D9, and diode D9, wherein...

[0011] One end of resistor R27 is connected to the voltage signal U-Back, and the other end of resistor R27 is connected to the inverting input of operational amplifier IC3A. The non-inverting input of operational amplifier IC3A is connected to one end of resistor R23, one end of resistor R24, and the output of operational amplifier IC3A. The other end of resistor R23 is grounded. The other end of resistor R24 is connected to one end of resistor R22 and the inverting input of operational amplifier IC3B. The non-inverting input of operational amplifier IC3B is connected to one end of resistor R28. The other end of resistor R28 is connected to one end of resistor R30 and the voltage signal U-Set. The output of operational amplifier IC3B is connected to one end of resistor R26. The other end of resistor R26 is connected to the cathode of diode D11 and the cathode of diode D9. The anode of diode D11 is connected to one end of resistor R29 and the output signal COMP.

[0012] In one embodiment, the current feedback control circuit includes: operational amplifier IC2A, operational amplifier IC2B, resistors R9, R12, R13, R14, R15, R16, and R17, diode D5, diode D6, and capacitor C3, wherein...

[0013] One end of resistor R13 is connected to the current signal I-Back. The other end of resistor R13 is connected to the non-inverting input of operational amplifier IC2A and one end of resistor R9. The inverting input of operational amplifier IC2A is connected to one end of resistor R17, one end of resistor R12, and the output of operational amplifier IC2A. The other end of resistor R19 is grounded. The other end of resistor R12 is connected to one end of resistor R30 and the inverting input of operational amplifier IC2B. Resistor R3... The other end of the IC2B is connected to one end of the capacitor C3. The non-inverting input of the operational amplifier IC2B is connected to one end of the resistor R15. The other end of the resistor R15 is connected to one end of the resistor R16 and the current signal I-Set. The output of the operational amplifier IC2B is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the cathodes of the diodes D6 and D5 respectively. The anode of the diode D6 is connected to the other end of the capacitor C3, one end of the resistor R29 and the output signal COMP respectively.

[0014] In one embodiment, the sampling circuit sends a voltage signal U-Back to the voltage feedback control circuit, and the sampling circuit sends a current signal I-Back to the current feedback control circuit.

[0015] In one embodiment, the operational amplifier IC3A forms a voltage follower, and the operational amplifier IC3B forms a proportional controller.

[0016] In one embodiment, the operational amplifier IC2A forms a voltage follower, and the operational amplifier IC2B forms a proportional-integral controller.

[0017] The technical solution provided by this utility model embodiment can include the following beneficial effects: the controllable constant current charging circuit for lithium battery cell measurement can realize controllable constant current charging from uA level to mA level, with a large adjustable range of constant current value, and can be applied to various types of lithium battery cells; and in the pulse method test of lithium battery cells, constant current charging starts from the initial stage, which improves the safety and protection of the test.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the present invention. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0020] Figure 1This is a schematic diagram of a controllable constant current charging circuit in lithium battery cell testing, according to an exemplary embodiment.

[0021] Figure 2 This is a circuit diagram illustrating the voltage feedback control circuit and the current feedback control circuit in a controllable constant current charging circuit for testing a lithium battery cell, according to an exemplary embodiment. Detailed Implementation

[0022] In this document, unless otherwise stated, the term "multiple" means two or more.

[0023] In this article, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0024] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0025] Where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0026] Figures 1-2 An embodiment of a controllable constant current charging circuit for testing lithium battery cells according to this invention is shown.

[0027] In this optional embodiment, the controllable constant current charging circuit in the lithium battery cell test includes: the lithium battery cell under test, a sampling circuit, a voltage feedback control circuit, a current feedback control circuit, a PWM control chip, a half-bridge inverter circuit, and an output power circuit. The output terminal of the lithium battery cell under test is connected to the input terminal of the sampling circuit. The output terminal of the sampling circuit is connected to the input terminals of both the voltage feedback control circuit and the current feedback control circuit. The output terminals of both the voltage feedback control circuit and the current feedback control circuit are connected to the input terminal of the PWM control chip. The output terminal of the PWM control chip is connected to the input terminal of the half-bridge inverter circuit. The output terminal of the half-bridge inverter circuit is connected to the input terminal of the output power circuit. The output terminal of the output power circuit is connected to both the lithium battery cell under test and the input terminal of the sampling circuit.

[0028] In this optional embodiment, the voltage feedback control circuit includes: operational amplifier IC3A, operational amplifier IC3B, resistors R22, R23, R24, R26, R27, R28, R29, R30, diode D9, and diode D9. One end of resistor R27 is connected to the voltage signal U-Back, and the other end of resistor R27 is connected to the inverting input of operational amplifier IC3A. The non-inverting input of operational amplifier IC3A is connected to one end of resistor R23, one end of resistor R24, and the output of operational amplifier IC3A. The other end of resistor R23 is grounded. The other end of resistor R24 is connected to one end of resistor R22 and the inverting input of operational amplifier IC3B. The non-inverting input of operational amplifier IC3B is connected to one end of resistor R28. The other end of resistor R28 is connected to one end of resistor R30 and the voltage signal U-Set. The output of operational amplifier IC3B is connected to one end of resistor R26. The other end of resistor R26 is connected to the cathodes of diode D11 and D9. The anode of diode D11 is connected to one end of resistor R29 and the output signal COMP.

[0029] In this optional embodiment, the current feedback control circuit includes: operational amplifier IC2A, operational amplifier IC2B, resistors R9, R12, R13, R14, R15, R16, and R17, diode D5, diode D6, and capacitor C3. One end of resistor R13 is connected to the current signal I-Back, and the other end of resistor R13 is connected to both the non-inverting input of operational amplifier IC2A and one end of resistor R9. The inverting input of operational amplifier IC2A is connected to one end of resistor R17, one end of resistor R12, and the output of operational amplifier IC2A. The other end of resistor R19... The circuit is grounded. The other end of resistor R12 is connected to one end of resistor R30 and the inverting input of operational amplifier IC2B. The other end of resistor R30 is connected to one end of capacitor C3. The non-inverting input of operational amplifier IC2B is connected to one end of resistor R15. The other end of resistor R15 is connected to one end of resistor R16 and the current signal I-Set. The output of operational amplifier IC2B is connected to one end of resistor R14. The other end of resistor R14 is connected to the cathodes of diode D6 and D5. The anode of diode D6 is connected to the other end of capacitor C3, one end of resistor R29, and the output signal COMP.

[0030] In this optional embodiment, the sampling circuit sends a voltage signal U-Back to the voltage feedback control circuit, and the sampling circuit sends a current signal I-Back to the current feedback control circuit.

[0031] In this optional embodiment, the operational amplifier IC3A forms a voltage follower, and the operational amplifier IC3B forms a proportional controller.

[0032] In this optional embodiment, the operational amplifier IC2A forms a voltage follower, and the operational amplifier IC2B forms a proportional-integral controller.

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1 As shown, this utility model provides a controllable constant current charging circuit for lithium battery cell measurement, which can achieve controllable constant current charging from the μA level to the mA level. The constant current value has a wide adjustable range and is applicable to various types of lithium battery cells. It possesses the following characteristics:

[0035] 1. The voltage feedback control circuit compares the set charging voltage signal U-set with the voltage signal U-Back sampled by the sampling circuit and then outputs the result.

[0036] 2. The current feedback control circuit compares the set charging current signal I-set with the current signal I-Back sampled by the sampling circuit and then outputs the result.

[0037] 3. The outputs of the voltage feedback control circuit and the current feedback control circuit are connected together, and the output COMP signal determines whether the PWM control chip outputs;

[0038] 4. After receiving the signal from the PWM control chip, the half-bridge inverter circuit starts to output, and combined with the output power circuit, it outputs a controllable and stable voltage.

[0039] Specifically, the voltage feedback control circuit and the current feedback control circuit are as follows: Figure 2 As shown, its characteristics include the following aspects:

[0040] 1. Operational amplifiers IC3A and IC3B, along with surrounding components, form a voltage feedback control circuit. IC3A acts as a voltage follower and buffer, while IC3B forms a proportional controller.

[0041] 2. Operational amplifiers IC2A and IC2B, along with surrounding components, form a current feedback control circuit; IC2A forms a voltage follower, acting as a buffer, while IC2B forms a proportional-integral controller.

[0042] 3. D5 and D6, D9 and D11, these two pairs of diodes ensure that the COMP voltage is always greater than 0;

[0043] 4. In the initial stage, I-Back = U-Back = 0, U-Set and I-Set are not 0. At this time, the IC3B proportional controller outputs high voltage, the IC2B proportional-integral controller also outputs high voltage, COMP is high voltage, and the PWM control chip outputs PWM signal.

[0044] 5. When the charging current is too large, I-Back > I-Set. At this time, the IC2B proportional-integral controller outputs a low-voltage signal, COMP is a low-voltage signal, and the PWM control chip stops outputting the PWM signal.

[0045] 6. In the next stage, I-Back = 0, U-Set > U-Back. At this time, the IC3B proportional controller outputs high voltage, the IC2B proportional-integral controller also outputs high voltage, COMP is high voltage, and the PWM control chip outputs PWM signal.

[0046] 7. Repeat this process until U-Set = U-Back, at which point charging ends and output stops.

[0047] This invention is not limited to the structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this invention is limited only by the appended claims.

Claims

1. A controllable constant current charging circuit for lithium battery cell testing, characterized in that, include: The tested lithium battery cell, sampling circuit, voltage feedback control circuit, current feedback control circuit, PWM control chip, half-bridge inverter circuit, and output power circuit are included. The output terminal of the lithium battery cell under test is connected to the input terminal of the sampling circuit. The output terminal of the sampling circuit is connected to the input terminals of the voltage feedback control circuit and the current feedback control circuit, respectively. The output terminals of the voltage feedback control circuit and the current feedback control circuit are both connected to the input terminal of the PWM control chip. The output terminal of the PWM control chip is connected to the input terminal of the half-bridge inverter circuit. The output terminal of the half-bridge inverter circuit is connected to the input terminal of the output power circuit. The output terminal of the output power circuit is connected to both the lithium battery cell under test and the input terminal of the sampling circuit.

2. The controllable constant current charging circuit for lithium battery cell testing according to claim 1, characterized in that, The voltage feedback control circuit includes: operational amplifier IC3A, operational amplifier IC3B, resistors R22, R23, R24, R26, R27, R28, R29, R30, diode D9, and diode D9, wherein... One end of resistor R27 is connected to the voltage signal U-Back, and the other end of resistor R27 is connected to the inverting input of operational amplifier IC3A. The non-inverting input of operational amplifier IC3A is connected to one end of resistor R23, one end of resistor R24, and the output of operational amplifier IC3A. The other end of resistor R23 is grounded. The other end of resistor R24 is connected to one end of resistor R22 and the inverting input of operational amplifier IC3B. The non-inverting input of operational amplifier IC3B is connected to one end of resistor R28. The other end of resistor R28 is connected to one end of resistor R30 and the voltage signal U-Set. The output of operational amplifier IC3B is connected to one end of resistor R26. The other end of resistor R26 is connected to the cathode of diode D11 and the cathode of diode D9. The anode of diode D11 is connected to one end of resistor R29 and the output signal COMP.

3. The controllable constant current charging circuit for lithium battery cell testing according to claim 2, characterized in that, The current feedback control circuit includes: operational amplifier IC2A, operational amplifier IC2B, resistors R9, R12, R13, R14, R15, R16, and R17, diodes D5 and D6, and capacitor C3. One end of resistor R13 is connected to the current signal I-Back. The other end of resistor R13 is connected to the non-inverting input of operational amplifier IC2A and one end of resistor R9. The inverting input of operational amplifier IC2A is connected to one end of resistor R17, one end of resistor R12, and the output of operational amplifier IC2A. The other end of resistor R19 is grounded. The other end of resistor R12 is connected to one end of resistor R30 and the inverting input of operational amplifier IC2B. Resistor R3... The other end of the IC2B is connected to one end of the capacitor C3. The non-inverting input of the operational amplifier IC2B is connected to one end of the resistor R15. The other end of the resistor R15 is connected to one end of the resistor R16 and the current signal I-Set. The output of the operational amplifier IC2B is connected to one end of the resistor R14. The other end of the resistor R14 is connected to the cathodes of the diodes D6 and D5 respectively. The anode of the diode D6 is connected to the other end of the capacitor C3, one end of the resistor R29 and the output signal COMP respectively.

4. The controllable constant current charging circuit for lithium battery cell testing according to claim 3, characterized in that, The sampling circuit sends a voltage signal U-Back to the voltage feedback control circuit, and the sampling circuit sends a current signal I-Back to the current feedback control circuit.

5. The controllable constant current charging circuit for lithium battery cell testing according to claim 3, characterized in that, The operational amplifier IC3A forms a voltage follower, and the operational amplifier IC3B forms a proportional controller.

6. The controllable constant current charging circuit for lithium battery cell testing according to claim 3, characterized in that, The operational amplifier IC2A forms a voltage follower, and the operational amplifier IC2B forms a proportional-integral controller.