A method for synchronously testing the resistance and capacitance of a battery cell under high voltage excitation

Abstract

The present invention relates to a method for synchronously testing the resistance and capacitance of a battery cell under high-voltage excitation, which connects a resistor, selects constant voltage and constant current parameters of a controllable test power supply; and sequentially uses #imgabs0# and #imgabs1# to measure the capacitance and resistance of the battery cell through constant current charging, constant voltage charging, and stop-charging sampling steps: the method for synchronously testing the resistance and capacitance of a battery cell before liquid injection under high-voltage excitation applies controllable constant current and constant voltage excitation, utilizes the charging and discharging characteristics of a cell capacitance-resistance model, calculates the capacitance and resistance of the battery cell during a high-voltage short-circuit test according to the voltage values ​​of each time state of a voltage waveform and a controlled charging current value during the test, and then accurately feeds back the actual state parameters of the battery cell, so as to provide product design and production process detection and control of the quality of the tested product.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and in particular to a method for synchronously testing the resistance and capacitance values ​​of a battery cell under high voltage excitation. Background Art

[0002] During the battery design and production process, the battery cell (referred to as the cell) stage before liquid filling will add corresponding high-voltage tests in each link such as winding, stacking, cold pressing, hot pressing, shelling, welding, and baking due to different battery production and manufacturing processes. On the one hand, high-voltage excitation is applied (depending on product differences, most test voltages are between 100V and 500V) to cause the weak points of insulation between the positive and negative electrodes of the cell to penetrate in order to identify problematic cells. On the other hand, the performance parameters related to the cell are measured to control the consistency of the product.

[0003] At present, during the short-circuit test of high-voltage excitation battery cells, only the insulation resistance value within a fixed time can be obtained through the insulation resistance test equipment, but the accurate resistance value cannot be measured, and the capacitance value of the battery cell cannot be measured under high-voltage excitation. If a multimeter is used to measure the resistance and capacitance gears, the process can only be carried out under weak current signals, and high-voltage excitation cannot be superimposed, so the short-circuit test of high-voltage excitation battery cells cannot be realized; and the resistance gear range of the multimeter is generally within 20MΩ, and the insulation resistance value of the actual battery cell under test ranges from a few megohms to hundreds of megohms, which obviously exceeds the range of the multimeter and cannot be effectively measured; if an LCR tester is used for measurement, it uses the output AC constant current signal to detect the amplitude and phase of the voltage signal after the signal flows through the tested product, and the capacitance and resistance values ​​can be measured in a wide range, but the LCR test signal is also a weak current signal, and it cannot be tested under the high voltage conditions required for the short-circuit test of the battery cell. Summary of the invention

[0004] The technical problem to be solved by the present invention is: to overcome the defects that during a high-voltage excitation short-circuit test, only the insulation resistance value within a fixed time can be obtained through an insulation resistance test device, and the capacitance value of a battery cell cannot be obtained, and that a multimeter and an LCR tester cannot superimpose high-voltage excitation to achieve synchronous testing, and provide a method for synchronously testing the resistance and capacitance values ​​of a battery cell under high-voltage excitation. The method applies a controllable constant-current and constant-voltage excitation, utilizes the charging and discharging characteristics of a cell capacitance-resistance model, calculates the capacitance value and resistance value of the battery cell during the high-voltage short-circuit test according to the voltage value of each time state of the voltage waveform and the controlled charging current value during the test, and thereby achieves synchronous testing of the resistance value and capacitance value of the battery cell under high-voltage excitation conditions.

[0005] The method for synchronously testing the resistance and capacitance of a battery cell under high voltage excitation comprises the following steps:

[0006] S1 connection resistance: insulation resistance of the positive and negative electrodes of the battery cell. It is set according to the battery cell test voltage requirement, and the constant voltage U and constant current I parameters of the controllable test power supply are selected;

[0007] S2 constant current charging: starting from time t0, the test power supply charges the battery cell with a constant current value I until time t1;

[0008] S3 constant voltage charging: starting from time t1, the voltage U1 of the power supply is tested and then switched to constant voltage to continue charging the battery cell until time t2;

[0009] S4 stop charging sampling: starting from time t2, after reaching the highest constant voltage value U2, stop charging the battery cell; monitor the state change of the voltage on the battery cell to the voltage value U3 at time t3;

[0010] S5 cell capacitance calculation: According to the formula Calculate the cell capacitance value;

[0011] S6 battery cell resistance calculation: According to the formula Calculate the cell resistance.

[0012] With this design, the battery cell is charged at a constant current to a target amplitude before liquid injection, and the cell capacitance is calculated based on the charging time, voltage amplitude and constant current charging current. The voltage drop amplitude per unit time is further monitored, and the cell resistance is calculated under the condition that the capacitance value has been measured during the charging process, thereby achieving synchronous testing of the resistance and capacitance values ​​of the battery cell under high-voltage excitation conditions.

[0013] As a condition optimization in the method, the insulation resistance value is greater than 10 MΩ, which is used to overcome the defect that the multimeter test cannot effectively measure due to over-range.

[0014] As a condition optimization in the method, the constant current charging is less than 100 mA. In conjunction with the insulation resistance value selection, the insulation resistance leakage current is ignored to calculate the capacitance value.

[0015] The present invention discloses a method for synchronously testing the resistance and capacitance of a battery cell under high-voltage excitation, which overcomes the defects that only the insulation resistance within a fixed time can be obtained by an insulation resistance test device during a high-voltage excitation short-circuit test, but the capacitance of the battery cell cannot be obtained, and that a multimeter and an LCR tester cannot superimpose high-voltage excitation to realize synchronous testing. The method applies a controllable constant-current and constant-voltage excitation, utilizes the charge and discharge characteristics of a cell capacitance-resistance model, calculates the capacitance and resistance of the battery cell during the high-voltage short-circuit test according to the voltage values ​​of each time state of a voltage waveform and a controlled charging current value during the test, and then accurately feeds back the actual state parameters of the battery cell for product design and production process detection and control of the quality of the tested product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following is a further description of a method for synchronously testing the resistance and capacitance of a battery cell under high voltage excitation according to the present invention in conjunction with the accompanying drawings:

[0017] Figure 1 It is a wireframe diagram of the specific steps of applying this method to test the resistance and capacitance values ​​of the battery cell;

[0018] Figure 2 This is the voltage waveform of the battery cell charge and discharge when the method is used for synchronous testing during high voltage short circuit testing. DETAILED DESCRIPTION

[0019] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In the description of the present invention, it should be understood that the terms "left", "right", "front", "back", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0021] The technical solution of the present invention is further described below with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0022] like Figure 1 , 2 As shown, the method for synchronously testing the resistance and capacitance of a battery cell under high voltage excitation comprises the following steps:

[0023] S1 connection resistance: insulation resistance of the positive and negative electrodes of the battery cell, set according to the battery cell test voltage requirement, select the constant voltage U and constant current I parameters of the controllable test power supply; the insulation resistance value is greater than 10 MΩ, which is used to overcome the defect that the multimeter test cannot effectively measure due to over-range;

[0024] S2 constant current charging: starting from time t0, the test power supply charges the battery cell with a constant current value I until time t1; the constant current charging is less than 100mA, and the insulation resistance value is selected, and the insulation resistance leakage current is ignored to calculate the capacitance value;

[0025] S3 constant voltage charging: starting from time t1, the voltage U1 of the power supply is tested and then switched to constant voltage to continue charging the battery cell until time t2;

[0026] S4 stop charging sampling: starting from time t2, after reaching the highest constant voltage value U2, stop charging the battery cell; monitor the state change of the voltage on the battery cell to the voltage value U3 at time t3;

[0027] S5 cell capacitance calculation: According to the formula Calculate the cell capacitance value;

[0028] S6 battery cell resistance calculation: According to the formula Calculate the cell resistance.

[0029] This method overcomes the defects that during the high-voltage excitation short-circuit test, only the insulation resistance value within a fixed time can be obtained through the insulation resistance test equipment, and the capacitance value of the battery cell cannot be obtained, and the multimeter and LCR tester cannot be superimposed with high-voltage excitation to achieve synchronous testing. It applies controllable constant-current and constant-voltage excitation, utilizes the charging and discharging characteristics of the battery cell capacitance and resistance model, and calculates the capacitance and resistance values ​​of the battery cell during the high-voltage short-circuit test according to the voltage value of each time state of the voltage waveform and the controlled charging current value during the test process, thereby realizing synchronous testing of the resistance value and capacitance value of the battery cell under high-voltage excitation conditions, and efficiently and accurately feeding back the actual state parameters of the battery cell for product design and production process detection and control of the quality of the tested product.

[0030] The above description shows the main features, basic principles, and advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments or embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, the above embodiments or embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0031] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for synchronously testing the resistance and capacitance of a battery cell under high voltage excitation, which is used to calculate the capacitance and resistance of the battery cell during a high voltage excitation short circuit test, and is characterized by: The Method The following steps are included: S1 connection resistance: insulation resistance of the positive and negative electrodes of the battery cell. It is set according to the battery cell test voltage requirement, and the constant voltage U and constant current I parameters of the controllable test power supply are selected; S2 constant current charging: starting from time t0, the test power supply charges the battery cell with a constant current value I until time t1; S3 constant voltage charging: starting from time t1, the voltage U1 of the power supply is tested and then switched to constant voltage to continue charging the battery cell until time t2; S4 stop charging sampling: starting from time t2, after reaching the highest constant voltage value U2, stop charging the battery cell; monitor the state change of the voltage on the battery cell to the voltage value U3 at time t3; S5 cell capacitance calculation: According to the formula Calculate the cell capacitance value; S6 cell resistance calculation: According to the formula Calculate the cell resistance.

2. The method for synchronously testing the resistance and capacitance of a battery cell under high voltage excitation according to claim 1, characterized in that: The insulation resistance is greater than 10 MΩ.

3. The method for synchronously testing the resistance and capacitance of a battery cell under high voltage excitation according to claim 2, characterized in that: The constant current charging is less than 100mA.

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