ER discharge cabinet and lithium sub-battery detection method

Abstract

The application discloses an ER discharge cabinet and a lithium sub-battery detection method. The ER discharge cabinet comprises an EtherCAT master station controller and at least one EtherCAT slave station node. The method is applied to the master station controller and comprises the following steps: controlling a full-electronic solid-state switch module to turn on a discharge loop; acquiring voltage time sequence data of the voltage acquisition module within a preset high-speed sampling period at a turning-on moment; calculating a voltage recovery slope characteristic value based on the voltage time sequence data; dynamically determining a delay time of load voltage judgment according to the voltage recovery slope characteristic value; after the delay time elapses, comparing the acquired load voltage with a preset load voltage threshold value, and outputting a judgment signal of the battery to be detected according to a comparison result. The adaptive delay strategy based on the voltage recovery slope is used to overcome the fixed delay misjudgment problem caused by the discrete state of the passivation film of the lithium sub-battery.

Description

Technical Field

[0001] This application relates to the field of battery testing technology, and in particular to an ER discharge cabinet and a method for testing lithium-ion batteries. Background Technology

[0002] Lithium thionyl chloride batteries require load discharge testing before leaving the factory. Existing technical solutions mainly fall into two categories: one uses a microcontroller to drive an electromagnetic relay matrix to switch the load resistor and collect the voltage, and the other uses a PLC to control a remote I / O module via an industrial bus to drive an intermediate relay to achieve load switching. However, both solutions rely on electromagnetic relays as switching devices, which have inherent drawbacks such as limited mechanical contact life, slow operating speed, and sampling noise introduced by closing bounce.

[0003] Meanwhile, the passivation film formed by lithium-ion batteries during long-term storage can cause a voltage hysteresis effect when the voltage drops sharply and then recovers slowly when a load is applied. The above solutions cannot adaptively adjust to the passivation state of different batteries, which leads to severely passivated batteries being misjudged as unqualified before the voltage recovers, or causing unnecessary waiting time for batteries that recover faster, affecting the production line cycle and testing accuracy. Summary of the Invention

[0004] This application provides an ER discharge cabinet and a lithium-ion battery testing method to solve the technical problem of low testing accuracy of existing lithium-ion battery testing solutions for batteries with passivation.

[0005] In a first aspect, this application provides a method for testing lithium-ion batteries based on an ER discharge cabinet. The ER discharge cabinet includes an EtherCAT master controller and at least one EtherCAT slave node, wherein the slave node is communicatively connected to the master controller via an EtherCAT bus; the EtherCAT slave node includes: The all-electronic solid-state switch module, controlled by the master station controller, is used to cut at least one programmable load resistor into the discharge circuit of the battery under test when a conduction signal is received. The voltage acquisition module is used to acquire the terminal voltage of the battery under test in real time and transmit the voltage data to the main station controller. The method is applied to the master station controller and includes: Control the all-electronic solid-state switch module to turn on the discharge circuit; The voltage timing data of the voltage acquisition module during a preset high-speed sampling period at the moment of conduction is acquired. Based on the voltage time series data, the voltage recovery slope characteristic value is calculated; The delay time for load voltage determination is dynamically determined based on the voltage recovery slope characteristic value. After the delay time, the collected load voltage is compared with the preset load voltage threshold, and the determination signal of the battery under test is output according to the comparison result.

[0006] In some embodiments, the all-electronic solid-state switch module is configured to have bidirectional blocking and soft-start functions, including: The core switching unit consists of a pair of MOSFETs connected back to back, which are used to bidirectionally block the discharge circuit using body diodes of opposite polarity in the off state. A drive interface unit is connected to the control terminal of the switch core unit and is used to receive the turn-on signal and drive the MOSFET to turn on. A soft-start network unit, coupled between the drive interface unit and the switch core unit, is used to delay the turn-on rate of the MOSFET when the turn-on signal arrives, so that the current in the discharge circuit is established at a preset gradual slope.

[0007] This embodiment utilizes a body diode of opposite polarity to achieve complete bidirectional blocking of the discharge circuit in the off state, preventing the battery under test from generating micro-current leakage through the parasitic diode during non-testing periods, thus avoiding battery capacity loss and measurement errors. The soft-start network unit delays the MOSFET's conduction rate when the conduction signal arrives, allowing the discharge current to establish itself at a preset gradual slope, effectively suppressing the severe impact of the surge current at the moment of conduction on the passivation film on the lithium-ion battery surface, and avoiding misjudgment caused by abnormal breakdown of the passivation film and excessive voltage drop due to instantaneous large current.

[0008] In some embodiments, acquiring the voltage timing data of the voltage acquisition module during a preset high-speed sampling period at the moment of conduction includes: Within the same EtherCAT bus cycle when the all-electronic solid-state switch module receives the conduction signal, the voltage acquisition module is triggered to enter burst sampling mode; In the burst sampling mode, the voltage acquisition module is controlled to continuously acquire the terminal voltage of the battery under test from the first preset time before conduction to the second preset time after conduction at a sampling frequency of ≥10KHz, so as to obtain the voltage timing data including the steady-state reference segment before conduction, the transient drop segment after conduction, and the voltage recovery and ramp-up segment.

[0009] In this embodiment, the solid-state switch is synchronously triggered to turn on and the voltage acquisition module enters burst sampling mode within the same EtherCAT bus cycle, ensuring precise alignment between the switch action and the sampling window and eliminating waveform capture deviation caused by asynchronous delay. The sampling frequency is set to no less than 10KHz, which is much higher than the conventional PLC analog signal acquisition rate, and can accurately characterize the voltage drop and recovery process of the lithium-ion battery within a millisecond time scale after the load is connected.

[0010] In some embodiments, calculating the voltage recovery slope characteristic value based on the voltage timing data includes: A sliding window mean filter is applied to the sampling point sequence corresponding to the voltage recovery ramp-up segment in the voltage timing data to eliminate the high-frequency oscillation noise generated at the moment the all-electronic solid-state switch module is turned on; Identify the first lowest voltage point data and the recovery point data at the first preset ratio position between the first lowest voltage point data and the estimated steady-state voltage in the filtered sampling point sequence; The voltage recovery slope characteristic value is calculated based on the first lowest point data and the recovery point data.

[0011] This embodiment effectively eliminates the interference of high-frequency oscillation noise remaining at the moment of conduction of the all-electronic solid-state switch module on the slope calculation by means of sliding window filtering, thereby improving the robustness of the algorithm. Then, in the filtered sequence, the lowest voltage point and the recovery point at the preset ratio position between the lowest voltage point and the estimated steady-state voltage are automatically identified. The voltage recovery slope feature value is calculated by the voltage difference and time difference between these two points, which accurately quantifies the recovery rate of the active area after the passivation film breakdown and effectively eliminates the uncertainty of single voltage threshold judgment.

[0012] In some embodiments, the delay time for load voltage determination is dynamically determined based on the voltage recovery slope characteristic value, including: The voltage recovery slope characteristic value is compared with a preset slope threshold table, which stores the mapping relationship between multiple slope intervals and corresponding delay times. If the voltage recovery slope characteristic value falls within the first slope range, then the delay time is determined as the first duration; If the voltage recovery slope characteristic value falls into the second slope range, then the delay time is determined as the second duration; Wherein, the lower limit of the first slope interval is less than the lower limit of the second slope interval, and the first duration is greater than the second duration.

[0013] In this embodiment, the slope feature value is compared with a preset slope threshold table. If the slope feature value falls into the low slope range (thick passivation film, slow recovery), a longer first delay time is automatically allocated to ensure that the voltage rises sufficiently before judgment, thus preventing the false rejection of qualified products. If the slope feature value falls into the high slope range (slight passivation, fast recovery), a shorter second delay time is allocated to shorten the test cycle and improve the production line cycle time.

[0014] In some embodiments, before dynamically determining the delay time for load voltage determination based on the voltage recovery slope characteristic value, a pre-screening step is also included: Determine whether the voltage recovery slope characteristic value is lower than a preset slope failure threshold; If the voltage recovery slope characteristic value is lower than the slope failure threshold, the battery under test is directly determined to be unqualified, and the test process is terminated. If the voltage recovery slope characteristic value is not lower than the slope failure threshold, then the step of dynamically determining the delay time for load voltage determination continues.

[0015] This embodiment effectively saves the unnecessary waiting time for obviously failed batteries through a pre-screening mechanism, further optimizes the test cycle, and reduces the average test cycle, which is particularly beneficial in mass production lines.

[0016] In some embodiments, before dynamically determining the delay time for load voltage determination based on the voltage recovery slope characteristic value, a secondary pre-screening step is included: Extract the second lowest voltage value at the moment of conduction from the voltage timing data; Determine whether the second minimum value is lower than the preset absolute minimum voltage threshold; If the second minimum value is lower than the preset absolute minimum voltage threshold, the battery under test is directly determined to be unqualified, and the test process is terminated.

[0017] This embodiment forms a dual rapid rejection defense line through a secondary pre-screening mechanism and slope screening, comprehensively controlling both recovery capability and minimum tolerance, further reducing the probability of false judgment and improving the overall reliability of the testing system.

[0018] In some embodiments, the ER discharge cabinet further includes a high-voltage insulation test module, which includes a programmable high-voltage power supply, a high-voltage resistant reed relay matrix, and an isolation protection circuit; the method further includes: After the comparison result of the battery under test is determined to be qualified, the high-voltage reed relay matrix is ​​controlled to completely disconnect the two poles of the battery under test from the all-electronic solid-state switch module and the voltage acquisition module, and connect them to the output terminal of the programmable high-voltage power supply. The programmable high-voltage power supply is controlled to output multiple incremental DC test voltage levels in sequence, and the leakage current value of the battery under test is obtained at each DC test voltage level. If the leakage current value at all DC test voltage levels is lower than the corresponding preset leakage current threshold, then the insulation performance of the battery under test is deemed qualified. During the operation of the high-voltage insulation test module, the isolation protection circuit controls the input terminal of the voltage acquisition module to be clamped to a safe voltage range.

[0019] This embodiment enables continuous automatic testing of discharge and insulation performance within a single device, eliminating the need for manual battery transfer and avoiding the risk of damage from secondary connections. Simultaneously, the stepped voltage boost test can detect insulation weaknesses that are only exposed under high voltage, ensuring the safe use of the battery under harsh operating conditions.

[0020] In some embodiments, each slave node corresponds to an independent battery testing station and is electrically isolated from each other. The discharge circuits of each battery under test are not connected by a common bus. The method further includes: The system time is broadcast to each slave node via the EtherCAT distributed clock protocol to synchronize the system time. A synchronization action time is preset and written into the synchronization manager register of each slave node, so that when the local clock of each slave node reaches the synchronization action time, the slave node synchronously outputs the conduction signal to its corresponding all-electronic solid-state switch module, so that multiple battery test stations conduct their corresponding discharge circuits at the same microsecond level.

[0021] This embodiment uses simultaneous parallel testing of multiple batteries under strictly consistent testing conditions to eliminate the time accumulation error of time-sharing testing, thereby improving the throughput of the production line while ensuring the comparability and consistency of the judgment results of each workstation.

[0022] Secondly, this application also provides an ER discharge cabinet, including an EtherCAT master controller, a memory, and at least one EtherCAT slave node. The memory is used to store a computer program, which, when executed by the EtherCAT master controller, implements the lithium-ion battery detection method described above.

[0023] Compared with the prior art, this application has the following beneficial effects: This application connects a master controller to at least one slave node via an EtherCAT real-time industrial Ethernet bus. Each slave node is configured with an all-electronic solid-state switch module and a voltage acquisition module. During testing, the master controller sends a turn-on signal to the all-electronic solid-state switch module via the bus, seamlessly connecting a programmable load resistor into the discharge circuit of the lithium-ion battery under test. Simultaneously, the voltage acquisition module is triggered to capture the voltage waveform at a preset high-speed sampling rate, obtaining continuous voltage timing data including the steady-state state before turn-on, the transient voltage drop during turn-on, and the voltage recovery ramp-up phase. This utilizes the all-electronic solid-state switch to eliminate mechanical contact bounce interference and switching noise, and the microsecond-level turn-on speed ensures the capture of the complete waveform of the voltage drop. The master station controller performs sliding filtering on the recovery climb segment data to extract voltage recovery slope feature values ​​to reflect the breakdown recovery rate of the battery passivation film. Based on the feature values, the corresponding delay waiting time is dynamically matched, allowing severely passivated batteries to obtain sufficient recovery time and slightly passivated batteries to be quickly judged. This achieves an adaptive delay strategy based on voltage recovery slope to overcome the fixed delay misjudgment problem caused by the discreteness of the passivation film state in lithium-ion batteries. At the same time, the EtherCAT bus architecture ensures the real-time performance and scalability of the testing process, significantly improving the accuracy, efficiency, and equipment reliability of lithium-ion battery factory testing. Attached Figure Description

[0024] Figure 1 This is a schematic flowchart illustrating the lithium-ion battery detection method based on an ER discharge cabinet according to an embodiment of this application. Figure 2 This is a schematic diagram of the ER discharge cabinet system architecture shown in an embodiment of this application; Figure 3 This is a structural block diagram of an ER discharge cabinet shown in an embodiment of this application. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] Figure 1 This is a schematic flowchart illustrating a lithium-ion battery testing method based on an ER discharge cabinet, as provided in an embodiment of this application. Figure 2 This is a schematic diagram of the system architecture of the ER discharge cabinet. Figure 2 As shown, the ER discharge cabinet includes an EtherCAT master controller 1 and at least one EtherCAT slave node 2. The slave node 2 is communicatively connected to the master controller 1 via an EtherCAT bus. The EtherCAT slave node 2 includes: The all-electronic solid-state switch module 21, controlled by the master station controller, is used to cut at least one programmable load resistor into the discharge circuit of the battery under test when a conduction signal is received. The voltage acquisition module 22 is used to acquire the terminal voltage of the battery under test in real time and transmit the voltage data to the master station controller.

[0027] See Figure 1 The lithium-thionyl chloride battery detection method based on the ER discharge cabinet in this application embodiment can be applied to the main station controller 1. The lithium-thionyl chloride battery detection method based on the ER discharge cabinet in this embodiment includes steps S101 to S105, detailed below: Step S101: Control the all-electronic solid-state switch module to turn on the discharge circuit.

[0028] In this step, the EtherCAT master controller sends a conduction control command to the designated slave node via the EtherCAT bus. This command is transmitted to the target slave node in the form of a Process Data Object (PDO) message within a bus cycle. After parsing the command, the slave node outputs a conduction signal to the all-electronic solid-state switch module, enabling the switch module to complete the state switching within microseconds, connecting the programmable load resistor between the positive and negative terminals of the lithium-ion battery under test, forming a discharge circuit. The all-electronic solid-state switch module uses semiconductor devices to achieve circuit connection, without mechanical contact action, thus eliminating contact bounce and arcing phenomena. The electrical noise at the moment of conduction is far lower than that of traditional relay solutions. The resistance value of the programmable load resistor can be pre-configured according to the battery model and test specifications, typically set to typical load values ​​such as 10Ω, 100Ω, or 1kΩ to meet the test requirements of different discharge rates.

[0029] Step S102: Obtain the voltage timing data of the voltage acquisition module during the preset high-speed sampling period at the moment of conduction.

[0030] In this step, the voltage acquisition module can employ a high-resolution Σ-Δ analog-to-digital converter, operating continuously at a sampling frequency of no less than 10kHz in burst sampling mode. The sampling window covers a first preset duration (e.g., 5ms) before conduction to a second preset duration (e.g., 50ms) after conduction. The pre-conduction period records the steady-state reference voltage under open-circuit battery conditions; the instantaneous conduction period captures the complete waveform of the voltage drop; and the post-conduction period continuously tracks the gradual recovery and rise of the voltage from the lowest point of the drop. The voltage acquisition module can use a Beckhoff EL3602 or similar EtherCAT analog input terminal, and the sampling rate and trigger mode are set by configuring the CoE object dictionary.

[0031] Step S103: Calculate the voltage recovery slope characteristic value based on the voltage timing data.

[0032] In this step, the voltage recovery slope characteristic value is used to quantitatively characterize the rate of recovery of the battery active area after the passivation film breaks down, thereby overcoming the uncertainty of the current technology that relies solely on fixed delay or a single threshold for judgment.

[0033] Step S104: Dynamically determine the delay time for load voltage determination based on the voltage recovery slope characteristic value.

[0034] In this embodiment, a delay mechanism is used to automatically provide a longer voltage stabilization waiting time for batteries with thick passivation films and slow recovery, avoiding misjudgments caused by making judgments before the voltage has fully recovered; while batteries with slight passivation and fast recovery have shorter waiting times, improving testing efficiency.

[0035] Step S105: After the delay time, the collected load voltage is compared with the preset load voltage threshold, and the determination signal of the battery under test is output according to the comparison result.

[0036] In this step, the preset load voltage threshold can be determined according to the battery specifications and can be the minimum allowable operating voltage of the battery model under a specified load resistance. The judgment signal can be transmitted to the upper production execution system via EtherCAT bus for data traceability, or it can drive local indicator lights or audible and visual alarm devices to prompt operators to classify and handle the situation. Optionally, a digital output module can be configured to drive green LEDs (pass) and red LEDs (fail) and display the load voltage value, judgment result, and historical statistical information of this test in real time on the HMI interface.

[0037] In some embodiments, the all-electronic solid-state switch module 21 is configured to have bidirectional blocking and soft-start functions, including: The core switching unit consists of a pair of MOSFETs connected back to back, which are used to bidirectionally block the discharge circuit using body diodes of opposite polarity in the off state. A drive interface unit is connected to the control terminal of the switch core unit and is used to receive the turn-on signal and drive the MOSFET to turn on. A soft-start network unit, coupled between the drive interface unit and the switch core unit, is used to delay the turn-on rate of the MOSFET when the turn-on signal arrives, so that the current in the discharge circuit is established at a preset gradual slope.

[0038] In this embodiment, the core switching unit consists of a pair of N-channel MOSFETs connected back-to-back in series. Specifically, the sources of the first MOSFET and the second MOSFET are connected together; the drain of the first MOSFET is connected to a programmable load resistor; and the drain of the second MOSFET is connected to either the positive or negative terminal of the battery under test. The gates of both MOSFETs are connected to the output of the drive interface unit. In the off state, the body diodes of the first MOSFET and the second MOSFET are oriented in opposite directions, forming a bidirectional blocking structure. This ensures that the discharge circuit is completely open in both directions, preventing the battery under test from generating microampere-level leakage current through the parasitic body diode during non-testing periods, thus avoiding slow battery capacity loss and crosstalk between multiple stations.

[0039] The drive interface unit can use a high-speed optocoupler (such as TLP2161) to electrically isolate the low-voltage control signal of the EtherCAT slave node from the MOSFET gate drive circuit. The isolation withstand voltage is not less than 2500Vrms, while providing sufficient gate drive current to ensure that the MOSFET turns on quickly.

[0040] The soft-start network unit consists of a charging resistor (typically 10kΩ to 100kΩ) connected in series between the optocoupler output and the MOSFET gate, and an acceleration turn-off diode connected in parallel across the resistor. When the turn-on signal arrives, the optocoupler output goes high, charging the MOSFET gate capacitor through the charging resistor. The gate voltage rises slowly according to the RC time constant, gradually increasing the MOSFET channel conduction level. The discharge circuit current establishes itself with a preset, gradually changing slope, preventing sudden current changes from impacting the passivation film. During turn-off, the gate capacitor discharges rapidly through the acceleration diode, achieving rapid MOSFET turn-off.

[0041] Optionally, the charging resistor can be an adjustable digital potentiometer, allowing the soft-start slope to be configured online via software to accommodate differences in the passivation film tolerance of different batches of batteries.

[0042] In some embodiments, step S102 includes: Within the same EtherCAT bus cycle when the all-electronic solid-state switch module receives the conduction signal, the voltage acquisition module is triggered to enter burst sampling mode; In the burst sampling mode, the voltage acquisition module is controlled to continuously acquire the terminal voltage of the battery under test from the first preset time before conduction to the second preset time after conduction at a sampling frequency of ≥10KHz, so as to obtain the voltage timing data including the steady-state reference segment before conduction, the transient drop segment after conduction, and the voltage recovery and ramp-up segment.

[0043] In this embodiment, when the master controller sends an EtherCAT frame containing a turn-on command, the slave controller simultaneously sets the digital output bit (for driving the solid-state switch) and the analog acquisition trigger bit in the hardware interrupt service routine upon frame arrival. This utilizes the synchronization characteristics of the EtherCAT distributed clock to ensure that the alignment error between the switch action moment and the sampling window start moment does not exceed one counting cycle (typically <100ns) of the slave's local clock. In burst sampling mode, the voltage acquisition module's ADC operates continuously at a sampling rate of ≥10kHz, and the sampled data is uploaded to the master controller's memory in real time via the EtherCAT mailbox protocol or the synchronization manager channel. Data from the first preset duration before turn-on (e.g., 5ms) is used to establish an open-circuit voltage baseline, and the second preset duration after turn-on (e.g., 50ms to 200ms) covers the complete process of passivation film breakdown and voltage recovery. The voltage timing data contains three clearly identifiable phases: the steady-state reference phase before conduction (stable voltage), the transient drop phase during conduction (sharp voltage drop), and the voltage recovery and ramp-up phase (slow voltage recovery to a new steady state), providing a complete physical process description for slope calculation.

[0044] Optionally, an FPGA or dedicated ASIC can be configured as a sampling timing controller on the slave node to achieve nanosecond-level precise synchronization between sampling triggering and switch driving, and to support the opening of a ring buffer inside the FPGA to store high-speed sampling data, avoiding data loss caused by EtherCAT bus bandwidth limitations.

[0045] In some embodiments, step S103 includes: A sliding window mean filter is applied to the sampling point sequence corresponding to the voltage recovery ramp-up segment in the voltage timing data to eliminate the high-frequency oscillation noise generated at the moment the all-electronic solid-state switch module is turned on; Identify the first lowest voltage point data and the recovery point data at the first preset ratio position between the first lowest voltage point data and the estimated steady-state voltage in the filtered sampling point sequence; The voltage recovery slope characteristic value is calculated based on the first lowest point data and the recovery point data.

[0046] In this embodiment, the sliding window mean filtering can be implemented as follows: set the window width N (e.g., N=7), and for the voltage recovery ramp-up sampling sequence V[i], output the filtered result. This effectively suppresses high-frequency ringing noise introduced by the gate-drain coupling capacitance during MOSFET turn-on. The noise frequency is typically in the range of 100kHz to 1MHz, which is much higher than the effective frequency band of the voltage recovery signal (<10Hz). Mean filtering can significantly improve the signal-to-noise ratio.

[0047] The identification of the first lowest point data can be achieved using a traversal search algorithm, finding the index position corresponding to the minimum voltage value in the filtered sequence. The estimated steady-state voltage Vsteady can be obtained by taking the arithmetic mean of the last M sampling points (e.g., M=50) of the steady-state reference segment before conduction. A typical value for the first preset proportional coefficient K can be 0.632, derived from the characteristic time constant position of the step response of a first-order RC circuit; or 0.9, corresponding to the practical engineering judgment point where the voltage recovers to 90% of the steady-state value. The location of the recovery point data can be achieved using a threshold comparison method, traversing backwards from the lowest point index to find the first value that satisfies the threshold. The sampling points. Slope eigenvalues. Where Vr is the voltage amplitude at the recovery point, Vmin is the voltage amplitude at the first minimum point, tr is the timestamp corresponding to the recovery point, and tmin is the timestamp corresponding to the first minimum point. That is, Vr, i.e. Vmin, For the filter sequence The sampling index number corresponding to the first lowest point of the medium voltage. Ts is the sampling index number corresponding to the recovery point, and Ts is the sampling period.

[0048] Alternatively, a piecewise linear fitting method can be used instead of two-point slope calculation: the sampled sequence from the lowest point to the recovery point is subjected to least-squares linear fitting, and the slope of the fitted line is used as the slope feature value. This method has better robustness to local noise. For batteries with obvious nonlinear characteristics in voltage recovery, a combination of multiple slope features or curve fitting parameters can also be used as feature values ​​to more comprehensively describe the passivation film recovery kinetics.

[0049] In some embodiments, step S104 includes: The voltage recovery slope characteristic value is compared with a preset slope threshold table, which stores the mapping relationship between multiple slope intervals and corresponding delay times. If the voltage recovery slope characteristic value falls within the first slope range, then the delay time is determined as the first duration; If the voltage recovery slope characteristic value falls into the second slope range, then the delay time is determined as the second duration; Wherein, the lower limit of the first slope interval is less than the lower limit of the second slope interval, and the first duration is greater than the second duration.

[0050] In this embodiment, the preset slope threshold table can be established through experimental calibration. For example, lithium-ion battery samples with different storage periods are selected, and their complete voltage recovery curves under standard load are measured. The time T95 required for the voltage to recover to 95% of the steady-state value is recorded. Simultaneously, the corresponding slope characteristic value S is calculated according to step S103. Multiple sets of (S, T95) data are segmented and statistically analyzed to determine the boundary values ​​of each slope interval and the corresponding recommended delay time. A typical threshold table includes 3 to 5 intervals, such as: low slope region (S < 0.5V / s, delay 15s), medium-low slope region (0.5 ≤ S < 1.5V / s, delay 8s), medium-high slope region (1.5 ≤ S < 3.0V / s, delay 3s), and high slope region (S ≥ 3.0V / s, delay 1s). The interval boundary values ​​and the number of supported intervals can be configured through a human-machine interface to adapt to the differences in passivation characteristics of different types of lithium-ion batteries.

[0051] Optionally, the delay time can be determined using a binary search or sequential matching algorithm. The calculated S value is compared with the upper and lower limits of each interval, and the corresponding delay value is read after locating the relevant interval. For example, a continuous function mapping can be used instead of a discrete interval mapping, such as... Parameters a, b, and c are determined through curve fitting, which eliminates parameter jumps at interval boundaries, ensuring a smooth and continuous change in delay time with the slope. Furthermore, upper and lower limit protection values ​​for the delay duration can be set, such as a minimum of 1 second and a maximum of 30 seconds, to prevent excessively short or long waiting times due to abnormal slope values. The dynamically determined delay time is written into the timer of the master station controller, used to trigger load voltage acquisition in step S105.

[0052] In some embodiments, a preliminary quick screening step is included before step 104: Determine whether the voltage recovery slope characteristic value is lower than a preset slope failure threshold; If the voltage recovery slope characteristic value is lower than the slope failure threshold, the battery under test is directly determined to be unqualified, and the test process is terminated. If the voltage recovery slope characteristic value is not lower than the slope failure threshold, then the step of dynamically determining the delay time for load voltage determination continues.

[0053] In this embodiment, the voltage recovery curves of known defective batteries (such as those with internal micro-short circuits or severe passivation failures) are analyzed, and the distribution range of their slope characteristic values ​​is extracted. The upper limit of this distribution is taken as the failure threshold. A typical failure threshold can be set to 0.1V / s to 0.2V / s. When the calculated voltage recovery slope characteristic value is lower than this failure threshold, it indicates that the battery passivation film cannot effectively break down and recover within a reasonable time, or that there is a micro-short circuit inside the battery that prevents voltage from being established. Such batteries cannot reach a qualified voltage level even if the waiting time is extended. After determining that the slope characteristic value is lower than the failure threshold, the system immediately outputs a "non-conforming" judgment signal, terminates the current test process, and releases the test station for the next battery. This pre-screening step is performed before the dynamic delay calculation to avoid ineffective delay waiting for obviously defective batteries.

[0054] Optionally, historical test data can be statistically analyzed to dynamically update the failure threshold, adapting it to process fluctuations in different batches of batteries. Simultaneously, the HMI interface can be configured to enable or disable the pre-screening function and the corresponding threshold parameters. This mechanism, together with subsequent load voltage determination, forms a hierarchical screening system: pre-screening quickly eliminates severely defective products, while dynamic delay determination accurately identifies boundary state batteries; the two work together to significantly improve overall testing efficiency.

[0055] In some embodiments, a secondary pre-screening step is included before step S104: Extract the second lowest voltage value at the moment of conduction from the voltage timing data; Determine whether the second minimum value is lower than the preset absolute minimum voltage threshold; If the second minimum value is lower than the preset absolute minimum voltage threshold, the battery under test is directly determined to be unqualified, and the test process is terminated.

[0056] In this embodiment, the lowest point value Vmin of the voltage drop at the moment of conduction is extracted from the voltage timing data and compared with a preset absolute minimum voltage threshold Vabs_th. The absolute minimum voltage threshold is set based on the following: when a lithium-ion battery is connected to a specified load resistor, its instantaneous minimum terminal voltage should not be lower than the lower limit of the device's minimum operating voltage. Even if the voltage subsequently recovers to a qualified level, an excessively low instantaneous voltage may cause the backend device to reset or malfunction. A typical Vabs_th can be set to 2.0V to 2.5V (for a lithium-ion battery rated at 3.6V). If Vmin is lower than this threshold, it indicates that the battery's internal resistance is too high or the passivation film is too dense, and it cannot provide the instantaneous current required for device startup in practical applications. The system directly determines it as unqualified and terminates the test. This step, together with the slope pre-screening, constitutes a dual rapid rejection defense. Slope screening focuses on the dynamic capability of voltage recovery, while minimum voltage screening focuses on the ultimate withstand capability at the moment of load application. Both provide rapid evaluation of battery performance from different dimensions.

[0057] Optionally, an interpolation algorithm can be used to improve the time resolution during Vmin identification. Based on discrete sampling points, the true simulated minimum point location and amplitude are determined by quadratic curve fitting, eliminating the quantization error between the sampling time and the true minimum point time. Simultaneously, the absolute minimum voltage threshold can be configured separately according to battery model and load conditions, stored in the recipe parameter table, and automatically retrieved based on the current workstation configuration during testing.

[0058] In some embodiments, the ER discharge cabinet further includes a high-voltage insulation testing module, which includes a programmable high-voltage power supply, a high-voltage resistant reed relay matrix, and an isolation protection circuit; the method further includes: After the comparison result of the battery under test is determined to be qualified, the high-voltage reed relay matrix is ​​controlled to completely disconnect the two poles of the battery under test from the all-electronic solid-state switch module and the voltage acquisition module, and connect them to the output terminal of the programmable high-voltage power supply. The programmable high-voltage power supply is controlled to output multiple incremental DC test voltage levels in sequence, and the leakage current value of the battery under test is obtained at each DC test voltage level. If the leakage current value at all DC test voltage levels is lower than the corresponding preset leakage current threshold, then the insulation performance of the battery under test is deemed qualified. During the operation of the high-voltage insulation test module, the isolation protection circuit controls the input terminal of the voltage acquisition module to be clamped to a safe voltage range.

[0059] In this embodiment, the high-voltage insulation test module physically shares battery access terminals with the discharge test module, and realizes time-division multiplexing through a high-voltage resistant reed relay matrix. The reed relay is selected with a contact withstand voltage of not less than 1000VDC and an insulation resistance greater than 10 12 Ω model, and the coil side is driven by an optocoupler for isolation, ensuring complete electrical isolation between the high-voltage loop and the control loop. After the discharge test is determined to be qualified, the master station controller first disconnects the all-electronic solid-state switch module and the voltage acquisition module from the battery, and then drives the reed relay to connect the positive and negative electrodes of the battery to the output end of the programmable high-voltage power supply. The programmable high-voltage power supply receives the voltage setting instruction from the master station via the EtherCAT bus, and sequentially outputs a plurality of increasing test voltage levels, such as 250V, 500V, 750V, and 1000V. The holding time of each level of voltage is configurable (typically 1 to 10 seconds). During the holding period of each level of voltage, the leakage current value is obtained through the sampling resistor connected in series in the high-voltage loop and the differential amplifier, and uploaded to the master station after ADC conversion. If the leakage current under all test voltage levels is lower than the corresponding preset threshold (for example, the leakage current is less than 10μA at 1000V), the insulation performance is determined to be qualified. The core of the isolation protection circuit is a pair of back-to-back connected low-leakage diodes, which clamp the input end of the voltage acquisition module to within ±0.7V; meanwhile, the input channel of the voltage acquisition module is configured to a high-impedance state during the high-voltage test, which further blocks the high-voltage intrusion path.

[0060] Optionally, a guard ring driving circuit can be added: during the high-voltage test, a buffer signal in phase with the test voltage is injected into the reference ground plane of the voltage acquisition module, so that the internal circuit of the module is at the same potential as the external high-voltage end, completely eliminating the leakage path. During the step-up process, the system monitors the change trend of the leakage current in real time. If a sudden current increase is detected (for example, exceeding the set slope threshold), the high-voltage output is immediately cut off and the insulation failure is determined, so as to prevent the battery from being damaged by breakdown.

[0061] In some embodiments, each of the slave nodes corresponds to an independent battery test station and is electrically isolated from each other, there is no common bus connection between the discharge loops of each of the batteries to be tested, and the method further comprises: Broadcasting a synchronous system time to each of the slave nodes through the EtherCAT distributed clock protocol; Presetting a synchronization action moment, and writing the synchronization action moment into the synchronization manager register of each of the slave nodes, so that when the respective local clock of the slave node reaches the synchronization action moment, the slave node synchronously outputs the turn-on signal to the corresponding all-electronic solid-state switch module, so that a plurality of the battery test stations turn on their respective corresponding discharge loops at the same microsecond-level moment.

[0062] In this embodiment, each EtherCAT slave node corresponds to an independent battery test station. Each slave node can be powered by an independent isolated DC-DC power module. There is no electrical connection between the stations. The discharge circuit of the battery under test is completely independent, which fundamentally eliminates the problem of mutual charging current interference between batteries inherent in the common bus structure.

[0063] Optionally, the synchronization mechanism for parallel testing is based on the EtherCAT distributed clock protocol: the master controller periodically sends EtherCAT data frames containing system time information, and the slave controllers (ESCs) of each slave node automatically synchronize their local clocks with the master reference clock, achieving a synchronization accuracy of ±100ns. The master station pre-sets the synchronization action time, such as a future time T_sync on the master timeline, and writes this time value to the synchronization manager start time register of each slave node through a write operation. Each slave node continuously compares its local synchronization clock with T_sync; when they are equal, a hardware trigger signal is automatically generated, which directly drives the all-electronic solid-state switch module to conduct. Because the local clocks of each slave station are synchronized with high precision, the switching action of all stations occurs at the same microsecond level. The voltage acquisition module trigger also adopts the same mechanism to ensure the synchronous alignment of the sampling windows of each station.

[0064] Optionally, an FPGA can be configured at the slave node, using the ESC synchronization signal SYNC0 / LATCH0 as the trigger source. Nanosecond-level precision turn-on pulse generation and sampling trigger timing control can be implemented within the FPGA. This parallel synchronous architecture ensures that the test throughput of the ER discharge cabinet is linearly proportional to the number of workstations, and that the test conditions at each workstation are strictly consistent, guaranteeing the comparability and consistency of the judgment results and meeting the high efficiency and high reliability requirements of mass production.

[0065] Figure 3 This is a schematic diagram of the structure of an ER discharge cabinet provided in one embodiment of this application. Figure 3 As shown, the ER discharge cabinet 3 in this embodiment includes: at least one EtherCAT master station controller 30 ( Figure 3 The diagram shows only one of the following: a memory 31 and at least one EtherCAT slave node 32, and a computer program 33 stored in the memory 31 and executable on the at least one master controller 30, wherein the master controller 30 executes the computer program 33 to implement the steps in any of the above method embodiments.

[0066] The ER discharge cabinet may include, but is not limited to, a master controller 30, a memory 31, and slave nodes 32. Those skilled in the art will understand that... Figure 3This is merely an example of ER discharge cabinet 3 and does not constitute a limitation on ER discharge cabinet 3. It may include more or fewer components than shown in the figure, or combine certain components, or different components, such as input / output devices, network access devices, etc.

[0067] In some embodiments, the memory 31 can be an internal storage unit of the ER discharge cabinet 3, such as a hard disk or memory of the ER discharge cabinet 3. In other embodiments, the memory 31 can also be an external storage device of the ER discharge cabinet 3, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the ER discharge cabinet 3. Furthermore, the memory 31 can include both internal storage units and external storage devices of the ER discharge cabinet 3. The memory 31 is used to store operating systems, applications, bootloaders, data, and other programs, such as the program code of computer programs. The memory 31 can also be used to temporarily store data that has been output or will be output.

[0068] In addition, this application embodiment also provides a computer-readable storage medium storing a computer program, which, when executed by the master station controller, implements the steps in any of the above method embodiments.

[0069] This application provides a computer program product that, when run on an ER discharge cabinet, causes the ER discharge cabinet to execute the steps described in the above-described method embodiments.

[0070] In the several embodiments provided in this application, it will be understood that each block in the flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the figures. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved.

[0071] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0072] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application for those skilled in the art.

Claims

1. A method for detecting lithium-thionyl phosphate batteries based on an ER discharge cabinet, characterized in that, The ER discharge cabinet includes an EtherCAT master controller and at least one EtherCAT slave node, wherein the slave node is communicatively connected to the master controller via an EtherCAT bus. The EtherCAT slave nodes include: The all-electronic solid-state switch module, controlled by the master station controller, is used to cut at least one programmable load resistor into the discharge circuit of the battery under test when a conduction signal is received. The voltage acquisition module is used to acquire the terminal voltage of the battery under test in real time and transmit the voltage data to the main station controller. The method is applied to the master station controller and includes: Control the all-electronic solid-state switch module to turn on the discharge circuit; The voltage timing data of the voltage acquisition module during a preset high-speed sampling period at the moment of conduction is acquired. Based on the voltage time series data, the voltage recovery slope characteristic value is calculated; The delay time for load voltage determination is dynamically determined based on the voltage recovery slope characteristic value. After the delay time, the collected load voltage is compared with the preset load voltage threshold, and the determination signal of the battery under test is output according to the comparison result.

2. The lithium-ion battery detection method as described in claim 1, characterized in that, The all-electronic solid-state switch module is configured to have bidirectional blocking and soft-start functions, including: The core switching unit consists of a pair of MOSFETs connected back to back, which are used to bidirectionally block the discharge circuit using body diodes of opposite polarity in the off state. A drive interface unit is connected to the control terminal of the switch core unit and is used to receive the turn-on signal and drive the MOSFET to turn on. A soft-start network unit, coupled between the drive interface unit and the switch core unit, is used to delay the turn-on rate of the MOSFET when the turn-on signal arrives, so that the current in the discharge circuit is established at a preset gradual slope.

3. The lithium-ion battery detection method as described in claim 1, characterized in that, The acquisition of voltage timing data during a preset high-speed sampling period at the moment of conduction by the voltage acquisition module includes: Within the same EtherCAT bus cycle when the all-electronic solid-state switch module receives the conduction signal, the voltage acquisition module is triggered to enter burst sampling mode; In the burst sampling mode, the voltage acquisition module is controlled to continuously acquire the terminal voltage of the battery under test from the first preset time before conduction to the second preset time after conduction at a sampling frequency of ≥10KHz, so as to obtain the voltage timing data including the steady-state reference segment before conduction, the transient drop segment after conduction, and the voltage recovery and ramp-up segment.

4. The lithium-ion battery detection method as described in claim 3, characterized in that, The step of calculating the voltage recovery slope characteristic value based on the voltage time series data includes: A sliding window mean filter is applied to the sampling point sequence corresponding to the voltage recovery ramp-up segment in the voltage timing data to eliminate the high-frequency oscillation noise generated at the moment the all-electronic solid-state switch module is turned on; Identify the first lowest voltage point data and the recovery point data at the first preset ratio position between the first lowest voltage point data and the estimated steady-state voltage in the filtered sampling point sequence; The voltage recovery slope characteristic value is calculated based on the first lowest point data and the recovery point data.

5. The lithium-ion battery detection method as described in claim 1, characterized in that, Based on the voltage recovery slope characteristic value, the delay time for load voltage determination is dynamically determined, including: The voltage recovery slope characteristic value is compared with a preset slope threshold table, which stores the mapping relationship between multiple slope intervals and corresponding delay times. If the voltage recovery slope characteristic value falls within the first slope range, then the delay time is determined as the first duration; If the voltage recovery slope characteristic value falls into the second slope range, then the delay time is determined as the second duration; Wherein, the lower limit of the first slope interval is less than the lower limit of the second slope interval, and the first duration is greater than the second duration.

6. The lithium-ion battery detection method as described in claim 1, characterized in that, Before dynamically determining the delay time for load voltage determination based on the voltage recovery slope characteristic value, a preliminary rapid screening step is also included: Determine whether the voltage recovery slope characteristic value is lower than a preset slope failure threshold; If the voltage recovery slope characteristic value is lower than the slope failure threshold, the battery under test is directly determined to be unqualified, and the test process is terminated. If the voltage recovery slope characteristic value is not lower than the slope failure threshold, then the step of dynamically determining the delay time for load voltage determination continues.

7. The lithium-ion battery detection method as described in claim 1, characterized in that, Before dynamically determining the delay time for load voltage determination based on the voltage recovery slope characteristic value, a secondary pre-screening step is also included: Extract the second lowest voltage value at the moment of conduction from the voltage timing data; Determine whether the second minimum value is lower than the preset absolute minimum voltage threshold; If the second minimum value is lower than the preset absolute minimum voltage threshold, the battery under test is directly determined to be unqualified, and the test process is terminated.

8. The lithium-ion battery detection method as described in claim 1, characterized in that, The ER discharge cabinet also includes a high-voltage insulation testing module, which includes a programmable high-voltage power supply, a high-voltage resistant reed relay matrix, and an isolation protection circuit; the method further includes: After the comparison result of the battery under test is determined to be qualified, the high-voltage reed relay matrix is ​​controlled to completely disconnect the two poles of the battery under test from the all-electronic solid-state switch module and the voltage acquisition module, and connect them to the output terminal of the programmable high-voltage power supply. The programmable high-voltage power supply is controlled to output multiple incremental DC test voltage levels in sequence, and the leakage current value of the battery under test is obtained at each DC test voltage level. If the leakage current value at all DC test voltage levels is lower than the corresponding preset leakage current threshold, then the insulation performance of the battery under test is deemed qualified. During the operation of the high-voltage insulation test module, the isolation protection circuit controls the input terminal of the voltage acquisition module to be clamped to a safe voltage range.

9. The lithium-ion battery detection method as described in claim 1, characterized in that, Each slave node corresponds to an independent battery testing station and is electrically isolated from each other. There is no common bus connection between the discharge circuits of each battery under test. The method further includes: The system time is broadcast to each slave node via the EtherCAT distributed clock protocol to synchronize the system time. A synchronization action time is preset and written into the synchronization manager register of each slave node, so that when the local clock of each slave node reaches the synchronization action time, the slave node synchronously outputs the conduction signal to its corresponding all-electronic solid-state switch module, so that multiple battery test stations conduct their corresponding discharge circuits at the same microsecond level.

10. An ER discharge cabinet, characterized in that, The device includes an EtherCAT master controller, a memory, and at least one EtherCAT slave node. The memory stores a computer program that, when executed by the EtherCAT master controller, implements the lithium-ion battery detection method as described in any one of claims 1 to 9.

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