Lithium Battery Protection Board Testing Methods and Systems

Abstract

A testing method and system for lithium battery protection boards is disclosed. The method includes: sampling the resonant frequency of a connector structure using an acoustic resonant sensing unit to obtain an acoustic baseline signal indicating the mechanical connection state of the connector; real-time acquisition of environmental vibration intensity and impact event time using a triaxial accelerometer and an impact sensor, and time alignment with the acoustic baseline signal; applying excitation pulses of a predetermined frequency to the connector at a preset cycle, and acquiring the real-time resonant response curve of the connector to the excitation pulses using the acoustic resonant sensing unit to calculate the baseline profile offset; comparing the baseline profile offset with a preset safety threshold to convert the acoustic offset into a loosening risk indicator based on the comparison result; and performing a load switching test of a predetermined amplitude in response to the loosening risk indicator to determine whether the connector is abnormal. This invention can promptly detect poor contact caused by changes in connector gaps due to vibration, ensuring the accuracy of the alarm.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery and electric vehicle technology, and more specifically, relates to a lithium battery protection board testing method and system. Background Technology

[0002] One of the key technologies for the development of electric bicycles and electric vehicles is the power lithium battery. A large number of individual lithium batteries are connected in series and parallel to form a lithium battery pack, providing power to electric bicycles and electric vehicles. Based on the characteristics of lithium batteries in practical applications, lithium-ion batteries have advantages over other batteries, such as high voltage, high capacity density, long lifespan, and no pollution. One of their biggest drawbacks is the need for a protection circuit. Due to the chemical characteristics of lithium-ion batteries, during normal use, a positive chemical reaction occurs within them, converting electrical energy into chemical energy. However, under certain conditions, such as overcharging, over-discharging, and overcurrent, chemical side reactions can occur inside the battery. These side reactions, if aggravated, can severely affect the battery's performance and lifespan, and may produce a large amount of gas, causing a rapid increase in internal pressure and potentially leading to an explosion and safety issues. Therefore, all lithium-ion batteries require a protection circuit to effectively monitor the battery's charging and discharging status and, under certain conditions, shut down the charging and discharging circuits to prevent damage to the battery, before they can be applied in practical production and daily life.

[0003] However, in mobile vehicles such as electric bicycles and intelligent handling robots, prolonged vibration and impact can easily cause the connectors between the battery and the protection board to loosen or break slightly. Existing technologies for testing lithium battery protection boards only detect short circuits / open circuits during functional or cyclic testing, making it difficult to capture in real time the poor contact caused by changes in connector gaps due to vibration. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to resolve the aforementioned defects and propose a lithium battery protection board testing method and system.

[0005] The present invention adopts the following technical solution.

[0006] The first aspect of this invention discloses a testing method for a lithium battery protection board. The method includes: sampling the resonant frequency of a connector structure using an acoustic resonant sensing unit to obtain an acoustic baseline signal of the connector's mechanical connection state; real-time acquisition of environmental vibration intensity and impact event time using a triaxial accelerometer and an impact sensor, and time alignment with the acoustic baseline signal; applying an excitation pulse of a set frequency to the connector according to a preset period, and acquiring the real-time resonant response curve of the connector to the excitation pulse through the acoustic resonant sensing unit to calculate the baseline profile offset; comparing the baseline profile offset with a preset safety threshold to convert the acoustic offset into a loosening risk index based on the comparison result; and performing a load switching test of a set amplitude in response to the loosening risk index to determine whether the connector is abnormal. The acoustic resonant sensing unit is disposed on the connector between the protection board and the lithium battery, and the triaxial accelerometer and impact sensor are fixed to the protection board. The load switching test involves multiple current switching monitoring of voltage and current at set time intervals under safe current conditions.

[0007] Furthermore, the step of sampling the resonant frequency of the connector structure through the acoustic resonant sensing unit to obtain the acoustic baseline signal of the connector's mechanical connection state includes: selecting a piezoelectric ceramic resonator with a corresponding resonant frequency range according to the connector's shell material and size to construct the acoustic resonant sensing unit, and arranging the piezoelectric ceramic resonator parallel to the surface of the connector's shell using a designed mounting bracket; connecting the two-terminal electrodes of the piezoelectric ceramic resonator to the acoustic acquisition interface of the main control board through a shielded twisted pair cable, configuring the corresponding measurement channel number and physical port mapping table in the main control board firmware, and setting the sampling rate, bandpass filter center frequency, and bandwidth in the acquisition configuration; triggering the excitation pulse in a vibration-free environment, and acquiring the resonant response within the first time period after the excitation pulse is triggered, so as to call FFT to calculate the baseline resonant frequency and generate the acoustic baseline signal.

[0008] Furthermore, the real-time acquisition of environmental vibration intensity and impact event time using a triaxial accelerometer and impact sensor, and time alignment with the acoustic baseline signal, includes: selecting the triaxial accelerometer and impact sensor according to the typical vibration spectrum range of the mobile vehicle, determining the mounting point on the protection board PCB, installing the triaxial accelerometer and impact sensor at the mounting point perpendicular to the plane of the protection board; fixing the triaxial accelerometer and impact sensor to the protection board bracket with screws and spring washers, and connecting the sensor output terminal to the ADC channel of the main control board through a shielded multi-core cable.

[0009] Furthermore, the method of using a triaxial accelerometer and an impact sensor to collect environmental vibration intensity and impact event time in real time, and aligning it with the acoustic baseline signal, further includes: applying a set gravitational acceleration to the protection plate along the X, Y, and Z axes on a horizontal plane to obtain voltage readings output in each axis direction, and calculating acceleration calibration coefficients based on the voltage readings; and based on the sampling configuration and dual-ring buffer structure of the loaded main control board, collecting acceleration data streams and impact data streams from the triaxial accelerometer and impact sensor in real time, and determining the environmental vibration intensity and impact event at each sampling point based on the acceleration data streams and impact data streams.

[0010] Furthermore, the step of applying an excitation pulse of a set frequency to the connector according to a preset period and obtaining the real-time resonant response curve of the connector to the excitation pulse through the acoustic resonant sensing unit to calculate the baseline profile offset includes: determining the excitation pulse based on the baseline resonant frequency, configuring the output power of the power amplifier, setting the pulse width, and issuing pulse control commands through the DAC interface of the main control board to construct an excitation pulse parameter set; periodically triggering the first excitation pulse according to the impact event time through a first timer, and triggering the second excitation pulse through a second timer when the impact sensor detects the impact event to construct a synchronous trigger signal sequence; acquiring time-domain data through an ADC and performing Fourier transform on the time-domain data to calculate the resonance peak feature set after each excitation; and plotting a frequency offset curve and an amplitude curve based on the resonance peak feature set and the synchronous trigger timestamp in the synchronous trigger signal sequence to determine the baseline profile offset.

[0011] Furthermore, comparing the baseline profile offset with a preset safety threshold to convert the acoustic offset into a loosening risk index based on the comparison result includes: calculating the average frequency, frequency standard deviation, and average amplitude and standard deviation based on the baseline resonant frequency and baseline resonant amplitude, and calculating the frequency offset and amplitude offset in combination with the resonant peak feature set; determining the preset safety threshold according to the three sigma principle and a preset safety factor; calculating the loosening risk index based on the frequency offset and amplitude offset; determining whether the loosening risk index is lower than a first threshold, and triggering a loosening alarm flag and outputting the current excitation timestamp, frequency offset, amplitude offset, and loosening risk index when the loosening risk index is not lower than the first threshold.

[0012] Furthermore, the step of performing a load switching test of a set amplitude in response to the loosening risk index to determine whether the connector is abnormal includes: generating an on / off sequence with an on / off period in the main control board based on the loosening risk index and the corresponding timestamp, and configuring a test current; during the load switching test, switching the test current on and off according to a set script using a current source, and acquiring the actual current and actual voltage at a set frequency through the ADC channel of the main control board to calculate the average current and average voltage; calculating the test impedance based on the average current and average voltage using Ohm's law, and calculating the impedance change in combination with the baseline impedance, so as to determine whether the connector is abnormal based on the impedance change.

[0013] A second aspect of this invention discloses a lithium battery protection board testing system, the system comprising: an acoustic signal sampling module for sampling the resonant frequency of a connector structure using an acoustic resonant sensing unit to obtain an acoustic baseline signal of the connector's mechanical connection state; a data synchronization module for real-time acquisition of environmental vibration intensity and impact event time using a triaxial accelerometer and an impact sensor, and time alignment with the acoustic baseline signal; and an offset calculation module for applying an excitation pulse of a set frequency to the connector according to a preset period, and obtaining the real-time resonant response of the connector to the excitation pulse through the acoustic resonant sensing unit. The system includes a baseline profile offset calculation module, a loosening risk quantification module, and a load switching test module. The latter is used to compare the baseline profile offset with a preset safety threshold to convert the acoustic offset into a loosening risk index based on the comparison result. The former is used to perform a load switching test of a set amplitude in response to the loosening risk index to determine if the connector is abnormal. The acoustic resonance sensing unit is mounted on the connector between the protection board and the lithium battery, and the triaxial accelerometer and impact sensor are fixed to the protection board. The load switching test involves multiple current switching operations at set time intervals under safe current conditions to monitor voltage and current.

[0014] A third aspect of the present invention discloses a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method described in the first aspect.

[0015] A fourth aspect of the present invention discloses a computer-readable storage medium having a computer program stored thereon, characterized in that the program, when executed by a processor, implements the steps of the method described in the first aspect.

[0016] The beneficial effects of the present invention are as follows: (1) The present invention provides an acoustic baseline signal of the current mechanical connection state of the docking plug by arranging a miniature acoustic resonance sensing unit in the connector area between the protection plate and the battery and using the sensor docking plug structure for non-invasive resonance frequency sampling, which facilitates subsequent comparison and detection of looseness. In addition, a triaxial accelerometer and an impact sensor are fixed on the protection plate to collect the environmental vibration intensity and impact event time points in real time and synchronize with the data of the acoustic resonance sensing unit. This enables real-time recording of vibration and impact times, providing a correlation reference for acoustic signal offset analysis and distinguishing between normal vibration and looseness signals.

[0017] (2) This invention periodically applies high-frequency excitation pulses of a safety level to the connector, uses an acoustic resonance sensing unit to collect the real-time resonance response curve of the connector, and calculates the offset with the baseline profile. Under vibration conditions, by comparing the baseline with the real-time resonance response, the change in resonance frequency caused by loosening can be accurately captured. At the same time, the acoustic offset is converted into a quantifiable loosening risk index, combined with monitoring the changes in voltage and current signals during short-term intermittent switching under safe current, to verify whether the momentary disconnection or impedance abnormality is caused by poor connector contact, and to confirm the acoustic detection results a second time, eliminating environmental noise or vibration false alarms, and ensuring the accuracy of the alarm. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the lithium battery protection board testing method provided by the present invention.

[0019] Figure 2 This is a schematic diagram of the lithium battery protection board testing system provided by the present invention. Detailed Implementation

[0020] The present application will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be construed as limiting the scope of protection of the present application.

[0021] like Figure 1 As shown, in one embodiment, a lithium battery protection board testing method includes the following steps: Step S110, sampling the resonant frequency of the connector structure through an acoustic resonant sensing unit to obtain the acoustic baseline signal of the mechanical connection state of the connector.

[0022] The acoustic resonance sensing unit is located on the connector between the protection board and the lithium battery.

[0023] In some embodiments, the lithium battery protection board testing method provided by the present invention includes the following steps in step S110: Step S111, selecting a piezoelectric ceramic resonator with a corresponding resonant frequency range to construct an acoustic resonant sensing unit according to the shell material and size of the connector, and arranging the piezoelectric ceramic resonator parallel to the shell surface of the connector using a designed mounting bracket.

[0024] Step S112: Connect the dual-ended electrodes of the piezoelectric ceramic resonator to the acoustic acquisition interface of the main control board through a shielded twisted pair cable, and configure the corresponding measurement channel number and physical port mapping table in the firmware of the main control board. At the same time, set the sampling rate, bandpass filter center frequency and bandwidth in the acquisition configuration.

[0025] Step S113: Trigger an excitation pulse in a vibration-free environment and collect the resonance response within the first time period after the excitation pulse is triggered, so as to call FFT to calculate the baseline resonant frequency and generate an acoustic baseline signal.

[0026] In a specific embodiment, the lithium battery protection board testing method provided by the present invention includes steps 1 to 5: Step 1, integration of connector acoustic resonance sensing unit.

[0027] A miniature acoustic resonance sensing unit is arranged in the connector area between the protection board and the battery. The sensor docking plug structure is used to perform non-invasive resonant frequency sampling, which provides an acoustic baseline signal of the current mechanical connection status of the docking plug, which is convenient for subsequent comparison and detection of looseness.

[0028] The process includes the following sub-steps: Sub-step 1.1, selection and structural design of acoustic resonant sensing unit.

[0029] Specifically, firstly, based on the connector housing material (e.g., aluminum alloy, plastic) and dimensions (length, width, height), a piezoelectric ceramic resonator with a resonant frequency range of 50kHz to 200kHz is selected. Next, a corresponding miniature mounting bracket is designed, using a stainless steel spring-loaded structure to ensure a tight fit with the connector and prevent loosening in vibration environments. Finally, the connecting screw holes and positioning clips between the bracket and the piezoelectric ceramic resonator are drawn in CAD software to ensure that the surface of the piezoelectric ceramic resonator is parallel to the metal housing surface of the connector during installation, with a gap ≤0.2mm. This ensures optimal coupling of the acoustic resonance sensing unit on the target structure and stable installation under subsequent vibration conditions, providing a high signal-to-noise ratio resonant signal.

[0030] Sub-step 1.2, Mechanical installation and position calibration.

[0031] Specifically, firstly, the designed mounting bracket is fixed to the connector housing using M1.2×3mm stainless steel screws, with the torque controlled at 0.05 N·m ± 10%. Secondly, the piezoelectric ceramic resonator is inserted into the bracket slot, ensuring that the piezoelectric ceramic resonator faces the connector housing. A 0.1mm thick acoustic conductive silicone is used on the bonding surface to optimize acoustic coupling. Finally, the distance d from the piezoelectric ceramic resonator to the connector housing is confirmed using a micrometer. The bracket shims are adjusted until d ≤ 0.2mm, and the positioning error ≤ 0.1mm, ensuring a stable sound wave transmission path and high coupling efficiency between the acoustic resonance sensing unit and the connector, thus enabling the resonant signal to accurately reflect changes in mechanical state.

[0032] Sub-step 1.3, Electrical connection and signal interface configuration.

[0033] Specifically, the dual-ended electrodes of the piezoelectric ceramic resonator are connected to the acoustic acquisition interface on the main control board via a shielded twisted-pair cable (≤50mm in length) to reduce electromagnetic interference. Next, the corresponding measurement channel number (e.g., CHAN-A) and physical port mapping table are configured in the main control board firmware, and the shielding layer is grounded to the system common ground. Finally, the sampling rate is set to 500kS / s in the software acquisition configuration, the bandpass filter center frequency is set to 100kHz, and the bandwidth is ±20kHz. This completes the signal path, ensuring the integrity and accuracy of the resonant signal during data acquisition, and providing reliable data for subsequent spectrum analysis.

[0034] Sub-step 1.4, Initial resonant frequency measurement and baseline generation.

[0035] Specifically, a high-frequency excitation pulse is triggered under vibration-free conditions (acceleration <0.01g), driven by a signal power P = 10mW ± 1mW from the main control board, with a duration T = 5ms. Afterwards, the resonant response within 200ms following the excitation is acquired, and the baseline resonant frequency is calculated using FFT. The expression is: In the formula, The equivalent inductance of the piezoelectric ceramic resonator (range: 0.1~1mH). The equivalent capacitance of the piezoelectric ceramic resonator (range: 100pF~1nF).

[0036] Finally, a baseline curve is generated with time on the x-axis and response amplitude on the y-axis, and stored in the baseline database to obtain the acoustic characteristics of the connector in a properly connected state. This provides a reference for subsequent online offset detection, thereby improving the accuracy of loosening judgment.

[0037] Step S120: The environmental vibration intensity and impact event time are collected in real time using a triaxial accelerometer and an impact sensor, and time-aligned with the acoustic baseline signal.

[0038] The triaxial accelerometer and impact sensor are fixed to the protective plate.

[0039] In some embodiments, the lithium battery protection board testing method provided by the present invention includes the following steps in step S120: Step S121, selecting a triaxial acceleration sensor and an impact sensor according to the typical vibration spectrum range of the mobile vehicle, determining the mounting point on the protection board PCB, and installing the triaxial acceleration sensor and the impact sensor at the mounting point perpendicular to the plane of the protection board.

[0040] In step S122, the triaxial accelerometer and impact sensor are fixed to the protective board bracket with screws and spring washers, and the sensor output is connected to the ADC channel of the main control board with a shielded multi-core cable.

[0041] In some embodiments, the lithium battery protection board testing method provided by the present invention further includes the following steps in step S120: Step S123, applying a set gravitational acceleration to the protection board along the X, Y, and Z axes on a horizontal plane to obtain voltage readings output in each axis direction, and calculating the acceleration calibration coefficient based on the voltage readings.

[0042] Step S124: Based on the sampling configuration and dual-ring buffer structure of the loaded main control board, the acceleration data stream and impact data stream from the triaxial accelerometer and impact sensor are collected in real time, and the environmental vibration intensity and impact event of each sampling point are determined according to the acceleration data stream and impact data stream.

[0043] In a specific embodiment, the lithium battery protection board testing method provided by the present invention includes step 2, dynamic vibration and impact signal acquisition. A triaxial accelerometer and an impact sensor are fixed on the protection board to collect environmental vibration intensity and impact event time points in real time, and synchronize the data with the acoustic resonant sensing unit. This achieves real-time recording of vibration and impact moments, provides a correlation reference for acoustic signal offset analysis, and distinguishes between normal vibration and loosening signals.

[0044] The process includes the following sub-steps: Sub-step 2.1, determining the sensor selection and installation location.

[0045] Specifically, a triaxial accelerometer (range +16g, sensitivity ≥2mV / g) and an impact sensor (range +200g, bandwidth 5kHz) are selected based on the typical vibration spectrum (5Hz-2kHz) of the mobile vehicle. Then, on the protective PCB board, a mounting point is determined no more than 10mm from the board edge, and the coordinates (x, y, z) are recorded relative to the origin at the lower right corner of the protective board. Finally, it is ensured that the three measuring axes of the triaxial accelerometer are aligned with the vehicle's axis within ±5°, and the impact sensor's axis is perpendicular to the protective board plane. Precise selection and positioning can capture the mechanical signals of the vehicle's vibration, shear, and impact along key directions to a greater extent, laying the foundation for accurately reconstructing the on-site working conditions.

[0046] Sub-step 2.2, mechanical fixing and electrical connection.

[0047] Specifically, the sensor selected in step 2.1 is fixed to the protective board bracket using M1.6×4mm screws and spring washers, with the torque controlled at 0.12 N·m ± 5%. The sensor output is connected to the corresponding ADC channel on the test main control board via a shielded multi-core cable (length ≤ 100 mm), with one end of the shield grounded. Afterwards, "ACC-X", "ACC-Y", "ACC-Z", and "SHOCK" are marked on the main control board terminal blocks, and pin connectivity is verified (resistance ≤ 5 Ω). This dual mechanical and electrical protection ensures the continuity and reliability of the sensor signal under vibration and shock environments, reducing the occurrence of loosening or broken wire blind spots.

[0048] Sub-step 2.3, sensor calibration and measurement channel calibration.

[0049] Specifically, after the device is finally installed and placed on a static horizontal surface (2.2), a known gravitational acceleration (e.g., 1g) is applied along the X, Y, and Z axes respectively. The original output values ​​of each axis channel are recorded, and the acceleration calibration coefficients in the X, Y, and Z axes are calculated based on these original output values. That is, the acceleration calibration coefficients in the X, Y, and Z axes are the reciprocals of the corresponding original output values ​​in the X, Y, and Z axes, respectively. Finally, a 50g standard pulse is generated for the impact sensor on the impact calibration bench, and the corresponding output is recorded to obtain the calibration coefficient of the impact measurement channel. The calibration coefficient of the impact measurement channel = 50 / the output recorded under the 50g standard pulse.

[0050] Sub-step 2.4: Data acquisition parameter configuration and real-time caching.

[0051] Specifically, based on the four calibration coefficients obtained in sub-step 2.3—namely, the acceleration calibration coefficients in the X, Y, and Z axes and the calibration coefficients for the impact measurement channel—the sampling rate is set in the main control firmware: 5 kS / s for the acceleration channel and 10 kS / s for the impact channel. Then, a bandpass filter is configured: 5 Hz to 2 kHz for the X, Y, and Z axes; and 100 Hz to 5 kHz for the impact channel. Simultaneously, a dual-loop buffer structure is enabled: the front loop has a size of 2 k samples for real-time calculation; the rear loop has a size of 10 k samples for event backtracking. By appropriately configuring sampling and buffering, sufficient historical data can be retained for comparing and analyzing the characteristics of impact events before and after they occur, while ensuring real-time performance.

[0052] Sub-step 2.5: Preliminary determination of real-time vibration intensity and impact event.

[0053] Specifically, based on the configuration in sub-step 2.4, acceleration data streams and impact data streams are collected in real time. The composite acceleration value is calculated based on the acceleration data stream, expressed as: In the formula, These are the accelerations along the X, Y, and Z axes at the nth sampling point, in m / s². 2 , This is the composite acceleration value for the nth sampling point.

[0054] The vibration intensity curve is plotted with time as the horizontal axis. The vertical axis is plotted in real time, and the root mean square value is recorded simultaneously. : In the formula, The acceleration composite value at the i-th sampling point. This represents the current size of the front loop buffer.

[0055] When the absolute value of the impact channel signal in the impact data stream exceeds a preset threshold (e.g., 30g), the timestamp of the corresponding event is recorded and marked as an impact event. This sub-step, by acquiring the vibration intensity and impact event list in real time, can be synchronized with the acoustic resonance offset data, accurately linking the vibration impact conditions with the risk of connector loosening.

[0056] Step S130: Apply an excitation pulse of a set frequency to the connector according to a preset period, and obtain the real-time resonance response curve of the connector to the excitation pulse through the acoustic resonance sensing unit to calculate the baseline profile offset.

[0057] In some embodiments, the lithium battery protection board testing method provided by the present invention includes the following steps in step S130: Step S131, determining the excitation pulse based on the baseline resonant frequency, configuring the output power of the power amplifier, setting the pulse width, and sending pulse control commands through the DAC interface of the main control board to construct the excitation pulse parameter set.

[0058] Step S132: The first excitation pulse is periodically triggered by the first timer according to the impact event time, and the second excitation pulse is triggered by the second timer when the impact sensor detects the impact event, so as to construct a synchronous trigger signal sequence.

[0059] Step S133: When each trigger signal in the synchronous trigger signal sequence is issued, time-domain data is acquired by ADC, and Fourier transform is performed on the time-domain data to calculate the resonant peak feature set after each excitation.

[0060] Step S134: Based on the resonant feature set and combined with the synchronous trigger timestamp in the synchronous trigger signal sequence, draw the frequency offset curve and amplitude curve to determine the baseline profile offset.

[0061] In a specific embodiment, the lithium battery protection board testing method provided by the present invention includes step 3, online acoustic excitation and resonance response measurement. High-frequency excitation pulses of a safety level are periodically applied to the connector. The real-time resonance response curve of the connector is acquired through an acoustic resonance sensing unit, and the offset is calculated against a baseline profile. Under vibration conditions, the change in resonance frequency caused by loosening is captured by comparing the baseline with the real-time resonance response.

[0062] It includes the following sub-steps: Sub-step 3.1, high-frequency excitation signal generation and power drive.

[0063] Specifically, firstly, based on the baseline resonant frequency determined in sub-step 1.4... Select excitation frequency Alternatively, the frequency can be swept within ±5kHz of the baseline resonant frequency to configure the power amplifier output power. This ensures that the excitation is sufficient to induce resonance without damaging the connector structure. Then, the pulse width is set. The main control board sends pulse control commands through its DAC interface. The drive unit adopts a Class D amplification structure and contains a low-pass filter to convert digital pulses into analog piezoelectric drive signals. This provides controllable, high-signal-noise acoustic excitation for the connector, enabling the resonant sensing unit to generate a measurable resonant response and ensuring the repeatability and stability of the measurement.

[0064] Sub-step 3.2, Synchronization Triggering and Timing Management.

[0065] Specifically, a dual-timer architecture is implemented in the main control board: Timer A is used to periodically trigger acoustic excitation at a frequency of... Timer B is used to timestamp impact events in the vibration and impact event timestamp list, ensuring that the minimum interval between the excitation pulse and the occurrence of a large impact is no less than 50ms. Subsequently, when the vibration / impact sensor detects any impact event, an additional excitation is initiated by interrupting Timer B. The signal sequence is marked as "event synchronization excitation," and the synchronization trigger signal sequence can be obtained based on the marked signal sequence. Finally, the synchronization trigger signal is sent to the power drive unit and the ADC acquisition unit, both of which start synchronously on the same system clock (1MHz). This sub-step, based on the stable periodic excitation, excites a resonant response immediately after a vibration or impact event to capture sudden loosening signals and enhance detection coverage.

[0066] Sub-step 3.3: Acquisition of time-domain resonant response signal.

[0067] Specifically, based on the synchronization trigger signal sequence determined in sub-step 3.2, the acquisition channel first acquires the output of the acoustic resonant sensing unit through a high-speed ADC at a sampling rate of 500 kS / s. The data is then amplified by an amplifier with a gain factor of 20 before being input to the ADC with a range of ±5V. Each time the synchronization trigger signal is reached, the ADC begins acquiring time-domain data, with 1024 sampling points. Finally, the acquired time-domain data is temporarily stored in the front-loop buffer, using a 16-bit integer format, with each sample index being 0, 1, ..., 1023. This sub-step obtains the time-domain response waveform of the connector after each acoustic excitation, providing raw data for subsequent spectrum analysis and ensuring data consistency when comparing against a baseline.

[0068] Sub-step 3.4: Time-domain to frequency-domain conversion and formant extraction.

[0069] Specifically, regarding the time-domain data obtained in step 3.3 Perform a Fast Fourier Transform (FFT) to obtain the corresponding frequency domain amplitude spectrum. The expression is: In the formula, This represents the time-domain data of the nth sampling point. For frequency subscripts, .

[0070] Next, calculate the corresponding actual frequency, expressed as: In the formula, .

[0071] Finally, in the frequency range Within, find the largest amplitude value. The frequency corresponding to the maximum amplitude value is recorded. This sub-step converts the time-domain response into frequency-domain features, extracts and quantizes the current formant frequency and amplitude of the connector, and provides an intuitive indicator for offset detection.

[0072] Sub-step 3.5: Real-time response curve generation and output.

[0073] Specifically, the maximum amplitude value obtained in step 3.4, along with its corresponding frequency and synchronization trigger timestamp, is stored in a database in chronological order and as a time-frequency-amplitude triplet. On the host computer or mobile device, the triplet in the database is accessed via API to plot two curves: a frequency offset curve (frequency-time) and an amplitude curve (amplitude-time). Next, a threshold alarm is configured. When the difference between the frequency and the reference frequency in the triplet, or the difference between the amplitude and the reference amplitude, exceeds a preset percentage, the corresponding amplitude or frequency is marked as an offset anomaly, and a corresponding alarm record is generated. This sub-step visualizes the dynamic changes in the resonant response as a curve, enabling real-time monitoring of the docking plug's health status and serving as a basis for subsequent loosening determination.

[0074] Step S140: The baseline profile offset is compared with a preset safety threshold to convert the acoustic offset into a loosening risk index based on the comparison result.

[0075] In some embodiments, the lithium battery protection board testing method provided by the present invention includes the following steps in step S140: Step S141, calculating the average frequency, standard deviation of frequency, average amplitude and standard deviation of amplitude based on the baseline resonant frequency and baseline resonant amplitude, and calculating the frequency offset and amplitude offset in combination with the resonant peak feature set.

[0076] Step S142: Determine the preset safety threshold according to the three sigma principle and the preset safety factor, and calculate the loosening risk index based on the frequency offset and amplitude offset.

[0077] Step S143: Determine whether the loosening risk index is lower than the first threshold. If the loosening risk index is not lower than the first threshold, trigger the loosening alarm flag and output the current excitation timestamp, frequency offset, amplitude offset, and loosening risk index.

[0078] In a specific embodiment, the lithium battery protection board testing method provided by the present invention includes step 4, determining the offset anomaly threshold and generating a loosening index. By comparing the real-time resonant response offset value with a preset safety threshold, a loosening index (e.g., the resonant frequency shift exceeding the threshold percentage or the cumulative offset of multiple consecutive times) is generated, converting the acoustic offset into a quantifiable loosening risk index to trigger subsequent actions.

[0079] The following sub-steps are included: Sub-step 4.1, calculation of baseline statistical characteristics.

[0080] Specifically, based on the set of baseline resonant frequencies and the set of baseline resonant amplitudes under static conditions, the average frequency and standard deviation of the set of baseline resonant frequencies, as well as the average amplitude and standard deviation of the set of baseline resonant amplitudes, are calculated. Through statistical analysis, the central tendency and dispersion of the baseline are obtained, providing an objective basis for subsequent threshold setting and avoiding misjudgments caused by simple percentage thresholds.

[0081] Sub-step 4.2, real-time offset calculation.

[0082] Specifically, based on the average frequency and average amplitude obtained in sub-step 4.1, the frequency offset and amplitude offset are calculated, where the frequency offset is the maximum amplitude value in the formant characteristics. The difference between the corresponding frequency and the average frequency, the amplitude offset is the maximum amplitude value. The difference between the amplitude and the average amplitude.

[0083] Sub-step 4.3, adaptive threshold setting.

[0084] Specifically, based on the frequency and amplitude offsets obtained in sub-step 4.2, and combined with the frequency and amplitude standard deviations obtained in sub-step 4.1, safety factors for both frequency and amplitude are determined as adjustable parameters. Thresholds are set according to the statistical three-sigma principle, or can be adjusted based on field experience, resulting in frequency and amplitude thresholds. The frequency threshold is the product of the frequency safety factor and the frequency standard deviation, and the amplitude threshold is the product of the amplitude safety factor and the amplitude standard deviation. Furthermore, the safety factors for both frequency and amplitude can be fine-tuned in the system configuration interface to adapt to different vehicles.

[0085] Sub-step 4.4: Calculation of loosening risk indicators.

[0086] Specifically, based on the frequency offset obtained in sub-step 4.2 and amplitude offset Combined with the frequency threshold determined in sub-step 4.3 and amplitude threshold Define loosening risk indicators The expression is: ;when This indicates that at least one offset exceeds the corresponding threshold, signifying a significant risk. This sub-step generates a quantifiable and comparable risk indicator by superimposing frequency and amplitude offsets on a unified scale, simplifying the alarm judgment logic and facilitating rapid system response.

[0087] Sub-step 4.5: Alarm flag generation and output.

[0088] Specifically, based on the risk indicators obtained in sub-step 4.4, the judgment logic is set as follows: In the formula, To loosen the alarm sign, when Simultaneously, the system outputs the timestamp, frequency, amplitude offset, and risk indicator value of this excitation. Finally, it pushes this data to the host computer or cloud, triggering subsequent verification processes. This sub-step transforms complex offset deviations into intuitive alarm indicators, facilitating technicians to quickly locate potential loosening issues and guide on-site maintenance and secondary verification.

[0089] Step S150: In response to the loosening risk indicator, perform a load switching test of a set amplitude to determine whether the connector is abnormal.

[0090] Among them, the load switching test involves monitoring voltage and current by repeatedly switching the current on and off at set time intervals under safe current conditions.

[0091] In some embodiments, the lithium battery protection board testing method provided by the present invention includes the following steps in step S150: Step S151, based on the loosening risk index and the corresponding timestamp, generating an on / off sequence with an on / off cycle in the main control board, and configuring the test current.

[0092] In step S152, during the load switching test, the test current is switched on and off according to the set script through the current source, and the actual current and actual voltage are obtained through the ADC channel of the main control board at a set frequency to calculate the average current and average voltage.

[0093] Step S153: Calculate the test impedance based on the average current and average voltage using Ohm's law, and calculate the impedance change in combination with the baseline impedance, so as to determine whether the connector is abnormal based on the impedance change.

[0094] In a specific embodiment, the lithium battery protection board testing method provided by this invention includes step 5, looseness verification and functional loopback testing. When the looseness alarm flag is triggered, the system automatically performs a small-amplitude load switching test, including short-term intermittent switching under safe current, and monitors changes in voltage and current signals to verify whether the momentary interruption or impedance abnormality is caused by poor connector contact. By confirming the acoustic detection results a second time, environmental noise or vibration false alarms can be effectively eliminated, ensuring the accuracy of the alarm.

[0095] The process includes the following sub-steps: Sub-step 5.1, preparing a short-time intermittent on / off test signal.

[0096] Specifically, an intermittent on / off sequence is generated in the test main control board, with an on / off cycle of 100ms on - 50ms off - 100ms on, and a total cycle not exceeding 500ms. Then, the test current is configured to 100mA ± 5mA, output through a current source, ensuring the current is below the rated maximum discharge current of the protection board. Finally, the script is loaded into the main control firmware task queue, with the associated trigger event being automatic execution after a 10ms delay following a timestamp. This sub-step simulates micro-disconnections in the connector through small-amplitude, short-duration intermittent on / off switching, re-verifying the circuit continuity of the protection board to eliminate false alarms caused by environmental or acoustic noise.

[0097] Sub-step 5.2: Real-time monitoring and acquisition of voltage and current.

[0098] Specifically, during the intermittent continuity test, the main control board's ADC channel simultaneously collects the load-side voltage (unit: V) and actual current (unit: A) at a sampling rate of 1 kS / s, with 150 sample points. The collected voltage and current are integrated according to the sequence format to obtain the load-side voltage set and the actual current set. The collected data is temporarily stored in the back loop buffer and then transmitted to the host computer without interruption via DMA.

[0099] Sub-step 5.3: Calculation of contact impedance changes and anomaly determination.

[0100] Specifically, the average voltage corresponding to the load-side voltage set obtained in sub-step 5.2 and the average current corresponding to the actual current set are calculated. Then, the ratio between the average voltage value and the average current value is calculated according to Ohm's law to obtain the test impedance. After that, the absolute value of the difference between the normal state baseline impedance (obtained through previous calibration, recommended range 0.5Ω~2Ω) and the test impedance is calculated. If the absolute value of this difference is ≥0.1Ω (set impedance threshold) or if a sample point where the voltage suddenly drops to zero occurs during intermittent switching, it is judged as "failure"; otherwise, it is judged as "pass". This sub-step quantifies the change in contact resistance or momentary interruption caused by loose connectors by comparing the baseline impedance and the test impedance, and verifies the accuracy of the acoustic detection alarm for the second time.

[0101] Sub-step 5.4 outputs the verification result and triggers the subsequent process.

[0102] Specifically, if the verification result obtained in sub-step 5.3 is "failure," the conclusion signal value is set to 1; otherwise, it is 0. The difference between the baseline impedance and the test impedance, the minimum voltage value, the maximum number of hourly interruptions, and the timestamp are written to a local log file and uploaded via the communication interface. The conclusion signal value determines whether management and maintenance should be performed. This sub-step explicitly outputs the functional loopback test results, completing the closed loop from acoustic detection to electrical verification. This ensures that only genuine loosening faults trigger subsequent maintenance procedures, avoiding resource waste caused by false alarms.

[0103] The lithium battery protection board testing system provided by the present invention is described below. The lithium battery protection board testing system described below can be referred to in correspondence with the lithium battery protection board testing method described above.

[0104] like Figure 2 As shown, in one embodiment, a lithium battery protection board testing system includes an acoustic signal sampling module, a data synchronization module, an offset calculation module, a loosening risk quantification module, and a load switching test module.

[0105] The acoustic signal sampling module is used to sample the resonant frequency of the connector structure through the acoustic resonant sensing unit in order to obtain the acoustic baseline signal of the mechanical connection state of the connector.

[0106] The data synchronization module is used to acquire environmental vibration intensity and impact event time in real time using a triaxial accelerometer and an impact sensor, and to time-align it with the acoustic baseline signal.

[0107] The offset calculation module is used to apply an excitation pulse of a set frequency to the connector according to a preset period, and to obtain the real-time resonance response curve of the connector to the excitation pulse through the acoustic resonance sensing unit in order to calculate the baseline profile offset.

[0108] The loosening risk quantification module is used to compare the baseline profile offset with a preset safety threshold, so as to convert the acoustic offset into a loosening risk index based on the comparison results.

[0109] The load switching test module is used to perform a load switching test of a set magnitude in response to a loosening risk indicator to determine whether the connector is abnormal.

[0110] The acoustic resonance sensing unit is located on the connector between the protection board and the lithium battery, while the triaxial accelerometer and impact sensor are fixed on the protection board. The load switching test involves monitoring the voltage and current by performing multiple current switching operations at set time intervals under safe current conditions.

[0111] The applicant of this invention has provided a detailed description of the embodiments of the invention in conjunction with the accompanying drawings. However, those skilled in the art should understand that the above embodiments are merely preferred embodiments of the invention. The detailed description is only intended to help readers better understand the spirit of the invention and is not intended to limit the scope of protection of the invention. On the contrary, any improvements or modifications made based on the inventive spirit of the invention should fall within the scope of protection of the invention.

Claims

1. A method of testing a lithium battery protection board, the method comprising: applying a voltage to a lithium battery protection board; and measuring a current through the lithium battery protection board. The method comprises: sampling the connector structure by an acoustic resonance sensing unit to obtain an acoustic baseline signal of the mechanical connection state of the connector; collecting environmental vibration intensity and impact event time in real time by using a three-axis acceleration sensor and an impact sensor, and time-aligning with the acoustic baseline signal; applying an excitation pulse of a set frequency to the connector according to a preset period, and obtaining a real-time resonance response curve of the connector to the excitation pulse by the acoustic resonance sensing unit to calculate a baseline profile offset; comparing the baseline profile offset with a preset safety threshold to convert an acoustic offset into a loosening risk indicator according to a comparison result; performing a load switching test of a set amplitude in response to the loosening risk indicator to determine whether the connector is abnormal; wherein the acoustic resonance sensing unit is arranged on a connector of a protection plate and a lithium battery, and the three-axis acceleration sensor and the impact sensor are fixed on the protection plate; the load switching test is a plurality of current on-off monitoring voltage and current at a set time interval under a safety current; the sampling of the connector structure by the acoustic resonance sensing unit to obtain the acoustic baseline signal of the mechanical connection state of the connector comprises: selecting a piezoelectric ceramic resonator of a corresponding resonance frequency range according to the shell material and size of the connector to construct the acoustic resonance sensing unit, and arranging the piezoelectric ceramic resonator in parallel on the surface of the shell of the connector through a designed mounting bracket; connecting the double-ended electrodes of the piezoelectric ceramic resonator to the acoustic acquisition interface of the main control board through a shielded twisted pair, configuring corresponding measurement channel numbers and physical port mapping tables in the main control board firmware, and setting sampling rate, band-pass filter center frequency and wideband in the acquisition configuration; triggering the excitation pulse in a vibration-free environment, and collecting resonance responses in a first time period after the excitation pulse is triggered to call FFT to calculate the baseline resonance frequency and generate the acoustic baseline signal; the collecting of environmental vibration intensity and impact event time in real time by using the three-axis acceleration sensor and the impact sensor, and the time-aligning with the acoustic baseline signal, comprises: selecting the three-axis acceleration sensor and the impact sensor according to the typical vibration frequency spectrum range of a mobile carrier, and determining the mounting point on the protection plate PCB, and mounting the three-axis acceleration sensor and the impact sensor vertically to the protection plate plane at the mounting point; fixing the three-axis acceleration sensor and the impact sensor on the protection plate bracket through screws and spring washers, and connecting the sensor output end to the ADC channel of the main control board through a shielded multi-core cable.

2. The method of claim 1, wherein, the collecting of environmental vibration intensity and impact event time in real time by using the three-axis acceleration sensor and the impact sensor, and the time-aligning with the acoustic baseline signal, further comprises: applying a set gravitational acceleration to the protection plate in X, Y and Z axial directions respectively on the horizontal plane to obtain voltage readings output in each axial direction, and calculating acceleration calibration coefficients based on the voltage readings; Based on the sampling configuration and double ring buffer structure loaded in the main control board, acceleration data stream and impact data stream from the three-axis acceleration sensor and impact sensor are collected in real time, and the environmental vibration intensity and impact event of each sampling point are determined according to the acceleration data stream and impact data stream.

3. The method of claim 2, wherein the test is performed by: The excitation pulse of a set frequency is applied to the connector according to a preset period, and the real-time resonance response curve of the connector to the excitation pulse is obtained through the acoustic resonance sensing unit to calculate the baseline profile offset, including: Based on the baseline resonance frequency, the excitation pulse is determined, and the power amplifier output power is configured, and the pulse width is set to issue pulse control instructions through the DAC interface of the main control board to construct an excitation pulse parameter set; The first excitation pulse is triggered periodically according to the impact event time through the first timer, and the second excitation pulse is triggered through the second timer when the impact sensor detects an impact event to construct a synchronous trigger signal sequence; When each trigger signal in the synchronous trigger signal sequence is issued, time domain data is collected through the ADC, and the time domain data is subjected to Fourier transform to calculate the resonance peak feature set after each excitation; Based on the resonance peak feature set, the synchronous trigger time stamp in the synchronous trigger signal sequence is combined to draw a frequency offset curve and an amplitude curve to determine the baseline profile offset.

4. The method of claim 3, wherein the test is performed by: The baseline profile offset is compared with a preset safety threshold to convert the acoustic offset into a loosening risk indicator according to the comparison result, including: Based on the baseline resonance frequency and baseline resonance amplitude, the frequency average, frequency standard deviation, and amplitude average and amplitude standard deviation are calculated, and the frequency offset and amplitude offset are calculated in combination with the resonance peak feature set; The preset safety threshold is determined according to the three sigma principle in combination with a preset safety factor, and the loosening risk indicator is calculated based on the frequency offset and amplitude offset; It is judged whether the loosening risk indicator is lower than a first threshold, and when the loosening risk indicator is not lower than the first threshold, a loosening alarm flag is triggered and the time stamp, frequency offset, amplitude offset and loosening risk indicator of the current excitation are output.

5. The method of claim 1, wherein, The load switching test of a set amplitude is performed in response to the loosening risk indicator to determine whether the connector is abnormal, including: Based on the loosening risk indicator and the corresponding time stamp, an on-off sequence with an on-off period is generated in the main control board, and a test current is configured; During the load switching test, the test current is turned on and off according to a set script through the current source, and the actual current and actual voltage are obtained through the main control board ADC channel at a set frequency to calculate the average current and average voltage; The test impedance is calculated based on the average current and average voltage through Ohm's law, and the impedance change is calculated in combination with the baseline impedance to determine whether the connector is abnormal according to the impedance change.

6. A lithium battery protection board testing system for performing the method of any one of claims 1-5, characterized by, The system comprises: An acoustic signal sampling module for sampling the resonance frequency of the connector structure through the acoustic resonance sensing unit to obtain the acoustic baseline signal of the mechanical connection state of the connector. The data synchronization module is configured to collect environmental vibration intensity and impact event time in real time by using the three-axis acceleration sensor and the impact sensor, and to perform time alignment with the acoustic baseline signal. The offset calculation module is configured to apply an excitation pulse of a set frequency to the connector at a preset period, and to obtain a real-time resonance response curve of the connector to the excitation pulse by the acoustic resonance sensing unit, so as to calculate a baseline profile offset. The loosening risk quantification module is configured to compare the baseline profile offset with a preset safety threshold, and to convert the acoustic offset into a loosening risk index according to a comparison result. The load switching test module is configured to perform a load switching test of a set amplitude in response to the loosening risk index, so as to determine whether the connector is abnormal. The acoustic resonance sensing unit is arranged on a connector of a protection plate and a lithium battery, and the three-axis acceleration sensor and the impact sensor are fixed on the protection plate. The load switching test is a current on-off monitoring voltage and current at a set time interval under a safety current.

7. A terminal comprising a processor and a storage medium; characterized in that: the storage medium is configured to store instructions; the processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-5.

8. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the steps of the method according to any one of claims 1-5.

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