Multi-channel calibration method and system for lithium battery internal resistance test equipment

Abstract

The invention discloses a calibration method and system for lithium battery internal resistance testing equipment, and belongs to the technical field of lithium battery testing. A main standard resistor is adopted to calibrate a plurality of test channels in sequence, firstly, a four-wire pin of the main standard resistor extends to form a calibration interface, and the interface is switched and connected to each test channel in sequence through a multiplexing switching module; after each channel is connected, the main standard resistor is measured, and the unique calibration coefficient of the channel is calculated and stored according to the comparison between the measurement result and the known resistance value of the standard resistor. According to the multi-channel calibration circuit, the intrinsic error among a plurality of standard resistors is fundamentally eliminated in a mode that a single standard resistor is matched with switching, the consistency and the precision of multi-channel calibration are remarkably improved, and meanwhile, the hardware cost is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery testing technology, specifically relating to a multi-channel calibration method and system for lithium battery internal resistance testing equipment. Background Technology

[0002] Internal resistance is a critical parameter in the production and quality inspection of lithium batteries. Multi-channel internal resistance testing equipment can measure the internal resistance of multiple batteries, greatly improving testing efficiency. To ensure measurement accuracy and consistency between channels, the testing equipment needs to be calibrated regularly.

[0003] Traditional calibration methods equip each test channel with an independent standard resistor (e.g., Figure 1 (As shown). During calibration, each channel is connected to its corresponding standard resistor for calibration. The drawbacks of this method are: First, each standard resistor has inherent accuracy errors and temperature drift, and these intrinsic differences are directly introduced into the calibration of each test channel, resulting in poor consistency between channels; second, multiple high-precision standard resistors need to be purchased, which is costly and complicated for subsequent metrological maintenance; finally, the calibration accuracy of the entire system is limited by the least accurate of the multiple standard resistors, making it impossible to achieve a unified highest-precision calibration. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, this invention provides a multi-channel calibration method and system for lithium battery internal resistance testing equipment. By sharing a master standard resistor, the intrinsic errors among multiple standard resistors are eliminated, achieving higher precision and consistency in calibration.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The first aspect of this invention relates to a multi-channel calibration method for a lithium battery internal resistance testing device, characterized in that the calibration method includes the following steps: S1: Switch the test channel to be calibrated to the calibration connection point using a multiplexing switcher; S2: The test channel outputs test current to the main standard resistor and measures the voltage drop across it; S3: The control and calculation unit calculates the resistance value measured by the test channel based on the output test current and the measured voltage drop. S4: Compare the calculated resistance value with the known precise resistance value of the main standard resistor, calculate the calibration coefficient of the test channel, and store it; S5: Repeat steps S1 to S4 until all test channels that need to be calibrated are calibrated.

[0006] Further, in step S1, the test channels are switched to the calibration connection points in a sequential polling manner.

[0007] The second aspect of the present application relates to a multi-channel synchronous calibration system for a lithium battery internal resistance testing device, characterized in that it comprises: a main standard resistor as the only reference; a calibration loop composed of multiple wires, used to extend the two current pins and the two voltage pins of the main standard resistor respectively to form multiple parallel shared calibration connection points; a multiplexing switching device for sequentially or selectively connecting multiple test channels of the internal resistance testing device to the shared calibration connection points; a control and calculation unit controlled by the battery internal resistance tester and the multiplexing switching device, used to control the multiplexing switching device and calculate the calibration coefficient of each channel based on the measurement value of the main standard resistor.

[0008] Further, in the calibration loop, the wire extending the voltage pin of the main standard resistor is a twisted shield wire.

[0009] Further, the multiplexing switching device is a relay matrix or a multiplexer.

[0010] The technical concept of the present application is that all channels of the present application trace back to the same physical standard resistor, and by using a single standard resistor in combination with switching, the intrinsic differences between multiple standard resistors are fundamentally eliminated, ensuring the absolute uniformity of the calibration reference of all channels.

[0011] Compared with the prior art, the beneficial effects of the present application are: 1. Extremely high calibration consistency: all channels trace back to the same physical standard resistor, fundamentally eliminating the intrinsic differences between multiple standard resistors, ensuring the absolute uniformity of the calibration reference of all channels.

[0012] 2. Higher calibration accuracy: a standard resistor with the highest accuracy level can be selected as the main reference, avoiding the "bucket effect" in traditional methods, so that the calibration accuracy of the entire testing system reaches the upper limit.

[0013] 3. Significant cost reduction: only one high-precision standard resistor is needed, replacing the traditional multiple standard resistor solution, greatly reducing hardware costs and subsequent metrological verification fees.

[0014] 4. Improved reliability: reducing the number of components and simplifying the system structure improves the long-term reliability of the entire calibration system. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a structural schematic diagram of a conventional multi-channel calibration system.

[0016] Figure 2 is a structural schematic diagram of a multi-channel calibration system of an embodiment of the present application. DETAILED DESCRIPTION

[0017] The specific embodiments of the embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the embodiments of the present application, and are not intended to limit the embodiments of the present application.

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0019] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with exemplary embodiments.

[0020] Embodiment 1

[0021] The present application is a multi-channel calibration method for a lithium battery internal resistance testing device, which comprises the following steps: S1: Switch the current test channel to be calibrated to the calibration connection point through a multiplexing switching device; S2: The test channel outputs a test current to the main standard resistor and measures the voltage drop across it; S3: The control and calculation unit calculates the resistance value measured by the test channel according to the output test current and the measured voltage drop; S4: Compare the calculated resistance value with the known accurate resistance value of the main standard resistor, calculate the calibration coefficient of the test channel, and store it; S5: Repeat steps S1 to S4 until all test channels that need to be calibrated are calibrated.

[0022] In this embodiment, in step S1, the test channels are switched to the calibration connection point in a sequential polling manner.

[0023] Embodiment 2

[0024] Reference Figure 2 , a multi-channel synchronous calibration system for a lithium battery internal resistance testing device, comprising: a main standard resistor as the only reference; a calibration loop composed of multiple wires, used to extend the two current pins and the two voltage pins of the main standard resistor respectively to form multiple parallel and shared calibration connection points; A multiplexing switching device is used to connect multiple test channels of an internal resistance testing device sequentially or selectively to the shared calibration connection point; A control and calculation unit is connected to the multiplexing switching device via a battery internal resistance tester. It is used to control the multiplexing switching device and calculate the calibration coefficient of each channel based on the measured value of the main standard resistor.

[0025] In this embodiment, the wire extending the voltage pin of the main standard resistor in the calibration circuit is a twisted-pair shielded wire.

[0026] In this embodiment, the multiplexing switching device is a relay matrix or a multiplexer.

[0027] All channels in this invention are traced back to the same physical standard resistor. By switching between multiple standard resistors using a single standard resistor, the intrinsic differences between multiple standard resistors are fundamentally eliminated, ensuring that the calibration reference of all channels is absolutely uniform.

[0028] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A multi-channel calibration method for a lithium battery internal resistance testing device, characterized in that, The calibration method includes the following steps: S1: Switch the test channel to be calibrated to the calibration connection point using a multiplexing switcher; S2: The test channel outputs test current to the main standard resistor and measures the voltage drop across it; S3: The control and calculation unit calculates the resistance value measured by the test channel based on the output test current and the measured voltage drop. S4: Compare the calculated resistance value with the known precise resistance value of the main standard resistor, calculate the calibration coefficient of the test channel, and store it; S5: Repeat steps S1 to S4 until all test channels that need to be calibrated are calibrated.

2. The multi-channel calibration method according to claim 1, characterized in that, In step S1, the test channel is switched to the calibration connection point in a sequential polling manner.

3. A multi-channel synchronous calibration system for lithium battery internal resistance testing equipment, characterized in that, include: A primary standard resistor serving as the sole reference; A calibration loop, consisting of multiple strands of wire, is used to extend the two current pins and two voltage pins of the main standard resistor to form multiple parallel, shared calibration connection points; A multiplexing switching device is used to connect multiple test channels of an internal resistance testing device sequentially or selectively to the shared calibration connection point; A control and calculation unit is connected to the multiplexing switching device via a battery internal resistance tester. It is used to control the multiplexing switching device and calculate the calibration coefficient of each channel based on the measured value of the main standard resistor.

4. The multi-channel synchronous calibration system according to claim 3, characterized in that, In the calibration circuit, the wire extending the voltage pin of the main standard resistor is a twisted-pair shielded wire.

5. The multi-channel synchronous calibration system according to claim 3, characterized in that, The multiplexing switching device is a relay matrix or a multiplexer.

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