Formation voltage control method based on adaptive PID

Abstract

The present application relates to the technical field of voltage control, in particular to a formation voltage control method based on adaptive PID, comprising the following steps: collecting target voltage trajectory, terminal voltage, charging current, negative voltage value and power supply state, constructing time sequence observation data, estimating the collective disturbance composed of current step corresponding to the charging current, lithium extraction polarization and negative voltage fluctuation corresponding to the negative voltage value by using extended state observer, and generating disturbance compensation amount. According to the disturbance intensity and polarization growth rate, the present application determines the micro dormancy opportunity and dormancy duration, so that the power supply duty ratio is reduced to zero for a short time, the continuous polarization process can be directly interrupted, and the accumulated electrochemical stress can be released. After the dormancy ends, the disturbance-free recovery is performed according to the time sequence observation data, the voltage mutation in the duty ratio reconstruction stage can be reduced, the formation voltage can be smoothly returned to the target trajectory, and the control stability and lithium extraction inhibition capacity can be improved.

Description

Technical Field

[0001] This invention relates to the field of voltage control technology, and in particular to a formation voltage control method based on adaptive PID. Background Technology

[0002] The field of voltage control technology mainly involves the detection, regulation, and stable control of the output voltage in electrical equipment, electrochemical devices, and their power supply circuits.

[0003] Existing voltage control typically relies on feedback regulation to adjust the deviation between the target voltage and the actual output voltage. In actual operation, load changes, current switching, line voltage drop, battery polarization, and negative voltage changes are often collectively reflected as a single voltage deviation, making it difficult to distinguish the source of the deviation and the evolution trend of the disturbance. When the formation current switches from a lower rate to a higher rate, the terminal voltage may rise rapidly due to the current step. Conventional feedback regulation can only correct the deviation after it has formed, which is prone to response lag and short-term fluctuations. When the internal polarization of the battery continues to increase, the terminal voltage response corresponding to the same control command will change over time. Fixed control parameters cannot simultaneously meet the requirements of fast tracking and oscillation suppression. If the parameters are too large, overshoot is likely to occur, and if the parameters are too small, the settling time will be prolonged. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and propose an adaptive PID-based formation voltage control method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an adaptive PID-based formation voltage control method, comprising the following steps:

[0006] Collect target voltage trajectory, terminal voltage, charging current, negative voltage value and power state to construct time series observation data. Use the extended state observer to estimate the lumped disturbance composed of the current step corresponding to the charging current, lithium plating polarization and the negative voltage fluctuation corresponding to the negative voltage value, and generate disturbance compensation amount.

[0007] The control deviation and deviation change rate are calculated based on the target voltage trajectory and the terminal voltage. The adaptive PID parameters of the adaptive PID controller are determined in conjunction with the disturbance compensation amount. The adaptive PID parameters include proportional parameters, integral parameters and derivative parameters.

[0008] An initial adjustment command is generated based on the adaptive PID parameters. The requested descent slope is determined based on the initial adjustment command. The initial adjustment command is limited according to a preset voltage descent slope limit and a preset output boundary to generate a limited adjustment command.

[0009] Identify lithium plating characteristic disturbances in the lumped disturbances and trigger a voltage suppression state;

[0010] When the restricted regulation command reaches the output boundary and the requested descent slope exceeds the voltage descent slope limit, the state of the integral term corresponding to the integral parameter is frozen, and the restricted regulation command is corrected by an anti-saturation tracking differentiator.

[0011] Based on the disturbance intensity and polarization growth rate of the lithium plating characteristic disturbance, a micro-sleep command is generated to control the power duty cycle corresponding to the power state to drop to zero during the sleep period.

[0012] After the specified sleep duration ends, a non-disruptive recovery is performed, and the conversion voltage is adjusted in a closed loop based on the time-series observation data.

[0013] Preferably, the steps of collecting target voltage trajectory, terminal voltage, charging current, negative voltage value, and power state to construct time-series observation data, and using an extended state observer to estimate the lumped disturbance composed of the current step corresponding to the charging current, lithium plating polarization, and negative voltage fluctuation corresponding to the negative voltage value, and generating the disturbance compensation amount are as follows:

[0014] The target voltage trajectory, terminal voltage, charging current, negative voltage value, duty cycle and limiting flag in the power supply state are collected according to the preset sampling period. Time alignment and range verification are performed to obtain the time series observation data.

[0015] Based on the time-series observation data, a discrete state relationship of the transformation voltage is established. The step change of the charging current, lithium plating polarization, fluctuation of the negative voltage value and power supply execution error are combined into an extended state. The voltage observation state and disturbance observation state of the extended state observer are updated periodically, and the disturbance observation state is corrected according to the difference between the terminal voltage and the voltage observation state.

[0016] The observed disturbance state is subjected to low-pass filtering to obtain the lumped disturbance. The lumped disturbance is multiplied by a preset calibration compensation coefficient to obtain the disturbance compensation amount. The single-cycle change of the lumped disturbance is limited to a preset disturbance change threshold.

[0017] Preferably, the steps of calculating the control deviation and deviation change rate based on the target voltage trajectory and the terminal voltage, and determining the adaptive PID parameters of the adaptive PID controller in conjunction with the disturbance compensation amount, are as follows:

[0018] The control deviation is obtained by subtracting the terminal voltage from the target voltage at the current sampling time. The difference between the control deviations at adjacent sampling times is divided by the preset sampling period to obtain the deviation change rate.

[0019] According to the absolute value of the control deviation, the absolute value of the rate of change of the deviation, and the absolute value of the disturbance compensation, a preset expert rule is matched. When the control deviation and the rate of change of the deviation have the same sign, the proportional parameter is increased and the integral parameter is decreased. When the control deviation and the rate of change of the deviation have opposite signs, the proportional parameter is decreased and the derivative parameter is increased.

[0020] When the disturbance compensation amount reaches the preset lithium plating determination boundary, the integral parameter is limited to less than half of the integral parameter corresponding to the preset stable sample without lithium plating, and the changes of the adjusted proportional parameter, integral parameter and derivative parameter in adjacent sampling periods are limited to obtain the adaptive PID parameter.

[0021] Preferably, the steps of generating an initial adjustment command based on the adaptive PID parameters, determining the requested voltage drop slope based on the initial adjustment command, and limiting the initial adjustment command according to a preset voltage drop slope limit and a preset output boundary to generate a limited adjustment command are as follows:

[0022] The control deviation is accumulated over time to obtain the integral state. The voltage request value is calculated based on the control deviation, the integral state, the rate of change of the deviation, the disturbance compensation amount, and the adaptive PID parameters, using the following formula: ,in, This indicates the requested voltage value, in volts. The proportional parameter is dimensionless. This represents the control deviation, in volts. This represents the integration parameter, in units of seconds. This indicates the integral state, in volt-seconds. The differential parameter is represented in seconds. This represents the rate of change of the deviation, in volts per second. This represents the disturbance compensation amount, in volts;

[0023] The requested voltage value is used as the initial adjustment command, and the requested descent slope is determined based on the difference between the initial adjustment commands at adjacent sampling times.

[0024] The voltage drop slope limit and the output boundary are determined based on the preset formation power supply calibration data. The requested drop slope is limited within the voltage drop slope limit, and the initial adjustment command is limited within the output boundary to obtain the restricted adjustment command.

[0025] Preferably, the step of identifying lithium plating characteristic disturbances in the lumped disturbances and triggering a voltage suppression state specifically includes:

[0026] A preset analysis time window corresponding to the lumped disturbance is extracted, and mean removal and discrete spectrum transformation are performed on the lumped disturbance within the analysis time window to obtain the disturbance spectrum. The frequency band energy of the disturbance spectrum within the lithium plating frequency range calibrated by the preset lithium plating cell sample is extracted.

[0027] The continuous decay duration of the terminal voltage within the analysis time window is calculated. When the frequency band energy reaches a preset lithium plating energy threshold, the continuous decay duration reaches a preset lithium plating duration threshold, and the absolute value of the difference between the negative voltage value and the preset negative voltage setting value reaches a preset negative voltage deviation threshold, the lumped disturbance within the analysis time window is determined as the lithium plating characteristic disturbance.

[0028] Based on the lithium plating characteristic disturbance write suppression flag, the adaptive PID parameters are switched to the suppression parameter group calibrated by the lithium plating cell sample, the suppression compensation coefficient is determined, and the disturbance compensation amount is updated according to the suppression compensation coefficient to trigger the voltage suppression state.

[0029] Preferably, the step of freezing the state of the integral term corresponding to the integral parameter and correcting the restricted regulation command by using an anti-saturation tracking differentiator when the restricted regulation command reaches the output boundary and the requested descent slope exceeds the voltage descent slope limit is as follows:

[0030] Read the integral state, compare the initial adjustment command with the limited adjustment command, and determine the limited descent state when the initial adjustment command is less than the lower limit of the output boundary and the absolute value of the requested descent slope exceeds the voltage descent slope limit;

[0031] In the restricted descent state, the accumulation of the integral state is stopped, the integral parameter is set to zero, and the integral state before entering the restricted descent state is saved to obtain the frozen integral state.

[0032] The anti-saturation tracking differentiator generates a back-calculation correction amount based on the difference between the restricted adjustment command and the terminal voltage. The back-calculation correction amount is superimposed on the restricted adjustment command at the next sampling time. When the initial adjustment command returns to the output boundary and the requested descent slope does not exceed the voltage descent slope limit, the descent restriction state is released, and the integral accumulation is restored according to the frozen integral state.

[0033] Preferably, the step of generating a micro-sleep command based on the disturbance intensity and polarization growth rate of the lithium plating characteristic disturbance, and controlling the power duty cycle corresponding to the power state to drop to zero during the sleep period, specifically includes:

[0034] A preset dormancy determination time window corresponding to the lithium plating characteristic disturbance is extracted. The disturbance intensity is determined based on the difference between the disturbance peak value within the dormancy determination time window and the preset lithium plating trigger amplitude. The polarization growth rate is determined based on the difference between the attenuation slope of the terminal voltage within two adjacent dormancy determination time windows.

[0035] The sleep duration is obtained by querying a preset sleep duration mapping table calibrated by cell model, formation temperature and rated capacity based on the disturbance intensity and polarization growth rate. The sleep duration is between 20 milliseconds and 80 milliseconds.

[0036] When the disturbance intensity reaches a preset micro-sleep trigger threshold and the polarization growth rate reaches a preset polarization growth threshold, the micro-sleep instruction is generated, the power supply duty cycle is reduced to zero at the next pulse width modulation cycle boundary, and the power supply duty cycle is kept at zero during the sleep duration.

[0037] Preferably, the step of performing a disturbance-free recovery after the said sleep duration ends, and adjusting the formation voltage in a closed loop based on the said time-series observation data, specifically includes:

[0038] When the sleep duration ends, the terminal voltage is read to obtain the recovery start voltage, and the frozen integral term state is read to obtain the recovery integral value;

[0039] The duty cycle of the power supply is increased from zero to the duty cycle corresponding to the restricted adjustment command by a recovery rise slope that is not greater than the preset rise slope of the formation power supply calibration, and the lumped disturbance is updated through the extended state observer during the increase process.

[0040] When the absolute value of the difference between the terminal voltage and the restricted adjustment command does not exceed twice the preset device voltage resolution and is maintained for three consecutive sampling cycles, the micro-sleep command is released, the integral accumulation is restored according to the restored integral value, and the disturbance compensation, parameter adjustment, command limiting and lithium plating identification are repeatedly executed according to the time-series observation data until the formation process ends.

[0041] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0042] This invention constructs time-correlated observation data by synchronously acquiring target voltage trajectory, terminal voltage, charging current, negative voltage value, and power supply status. This data can uniformly map current steps, lithium plating polarization, negative voltage fluctuations, and power supply execution deviations during the formation process into a lumped disturbance, generating a feedforward compensation quantity. This ensures the control process no longer relies solely on the static deviation between the target voltage and terminal voltage. By jointly adjusting proportional, integral, and derivative parameters based on control deviation, deviation change rate, and disturbance compensation quantity, response speed, steady-state accuracy, and oscillation suppression capabilities can be balanced during current switching, polarization enhancement, and negative voltage change stages. By comparing the requested descent slope, voltage descent slope limit, and output boundary, the initial adjustment command is limited to the physical capabilities of the formed power supply, preventing the control command from exceeding the actual execution capacity. Identifying lithium plating characteristic disturbances and triggering voltage suppression states allows voltage regulation to shift from general error correction to proactive intervention against lithium plating risks. Freezing the integral term state when the restricted adjustment command reaches the output boundary and the descent request exceeds the limit, and correcting the control output according to the restricted adjustment command, can suppress continuous integral accumulation and reverse overshoot after disturbance subsidence. The timing and duration of micro-dormancy are determined based on the disturbance intensity and polarization growth rate, allowing the power supply duty cycle to drop to zero briefly. This directly interrupts the continuous polarization process and releases accumulated electrochemical stress. After the dormancy ends, perturbation-free recovery is performed based on time-series observation data, which reduces voltage spikes during the duty cycle reconstruction phase and allows the formation voltage to smoothly return to the target trajectory, thereby improving control stability and lithium plating suppression capability. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the steps of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0045] Please see Figure 1 This invention provides a technical solution, a formation voltage control method based on adaptive PID, comprising the following steps:

[0046] Collect target voltage trajectory, terminal voltage, charging current, negative voltage value and power state to construct time series observation data. Use the extended state observer to estimate the lumped disturbance composed of current step corresponding to charging current, lithium plating polarization and negative voltage fluctuation corresponding to negative voltage value, and generate disturbance compensation amount.

[0047] The control deviation and deviation change rate are calculated based on the target voltage trajectory and terminal voltage. The adaptive PID parameters of the adaptive PID controller are determined in combination with the disturbance compensation amount. The adaptive PID parameters include proportional parameters, integral parameters and derivative parameters.

[0048] An initial regulation command is generated based on the adaptive PID parameters. The requested voltage drop slope is determined based on the initial regulation command. The initial regulation command is limited according to the preset voltage drop slope limit and the preset output boundary to generate a limited regulation command.

[0049] Identify lithium plating characteristic disturbances in lumped disturbances and trigger voltage suppression state;

[0050] When the restricted regulation command reaches the output boundary and the requested descent slope exceeds the voltage descent slope limit, the state of the integral term corresponding to the integral parameter is frozen, and the restricted regulation command is corrected by the anti-saturation tracking differentiator.

[0051] Micro-sleep commands are generated based on the perturbation intensity and polarization growth rate of lithium plating characteristic perturbations, and the power duty cycle corresponding to the control power state is reduced to zero during the sleep period.

[0052] After the dormancy period ends, a non-disruptive recovery is performed, and the conversion voltage is adjusted in a closed loop based on the time-series observation data.

[0053] In this embodiment, the steps of collecting target voltage trajectory, terminal voltage, charging current, negative voltage value, and power supply status to construct time-series observation data, and using an extended state observer to estimate the lumped disturbance composed of current step corresponding to charging current, lithium plating polarization, and negative voltage fluctuation corresponding to negative voltage value, and generating disturbance compensation amount are as follows: Collect the target voltage trajectory, terminal voltage, charging current, negative voltage value, and duty cycle and limiting flag in the power supply status according to a preset sampling period, perform time alignment and range verification to obtain time-series observation data; establish the discrete state relationship of the formation voltage based on the time-series observation data, merge the step change of charging current, lithium plating polarization, fluctuation of negative voltage value, and power supply execution error into an extended state, update the voltage observation state and disturbance observation state of the extended state observer periodically, and correct the disturbance observation state according to the difference between the terminal voltage and the voltage observation state; perform low-pass filtering on the disturbance observation state to obtain the lumped disturbance, multiply the lumped disturbance by a preset calibration compensation coefficient to obtain the disturbance compensation amount, and limit the single-cycle change of the lumped disturbance within a preset disturbance change threshold.

[0054] Specifically, the target voltage trajectory, terminal voltage, charging current, negative voltage value, duty cycle, and limiting flag are read according to a 20ms sampling period. The sampling sequence number is uniformly marked using the controller clock. Data with the same sequence number are grouped into observation records. Data with an arrival time deviation of no more than 10ms are included in the current record; data with a deviation exceeding 10ms are marked invalid and the valid value of the previous cycle is used. 10ms is taken as half of the sampling period. Based on the calibration data of the formation power supply and sensor rated range (e.g., terminal voltage limited to 0V to 5V, charging current limited to 0A to 300A, negative voltage value limited to -80kPa to 0kPa, and duty cycle limited to 0 to 1), the valid observation records are arranged by sampling sequence number to obtain time-series observation data. Discrete state relationships are established based on the changes in terminal voltage, charging current step amplitude, negative voltage value, and duty cycle between adjacent cycles. Known inputs that cannot be... The explained voltage change is categorized into the extended state. The difference between the terminal voltage and the voltage observation state is used to correct the disturbance observation state periodically. The correction gain is tuned through 1000 stable sample periods without lithium plating. For example, if the observation error is kept within 5mV when the gain is 0.35, then it is set to 0.35. A first-order low-pass filter with a cutoff frequency of 5Hz is used for the disturbance observation state. The cutoff frequency is half of the upper limit of the current switching frequency of 10Hz to obtain the lumped disturbance. The calibration compensation coefficient is the median of the ratio of the stable sample terminal voltage change to the lumped disturbance change. For example, 24mV divided by 20mV gives 1.2. Multiplying the lumped disturbance by 1.2 gives the disturbance compensation amount. The disturbance change threshold is the 95th percentile of the absolute value of the single-cycle change of the stable sample. For example, when the 95th percentile is 8mV, the single-cycle change exceeding 8mV is limited to 8mV to obtain the restricted disturbance compensation amount.

[0055] In this embodiment, the steps for calculating the control deviation and deviation change rate based on the target voltage trajectory and terminal voltage, and determining the adaptive PID parameters of the adaptive PID controller in conjunction with the disturbance compensation amount, are as follows: The target voltage at the current sampling time is subtracted from the terminal voltage to obtain the control deviation; the difference in control deviation between adjacent sampling times is divided by a preset sampling period to obtain the deviation change rate; based on a preset expert rule matching the absolute value of the control deviation, the absolute value of the deviation change rate, and the absolute value of the disturbance compensation amount, when the control deviation and the deviation change rate have the same sign, the proportional parameter is increased and the integral parameter is decreased; when the control deviation and the deviation change rate have opposite signs, the proportional parameter is decreased and the derivative parameter is increased; when the disturbance compensation amount reaches a preset lithium plating determination boundary, the integral parameter is limited to within half of the integral parameter corresponding to a preset stable sample without lithium plating, and the changes in the adjusted proportional parameter, integral parameter, and derivative parameter in adjacent sampling periods are limited to obtain the adaptive PID parameters.

[0056] Specifically, the control deviation is calculated based on the target voltage and the terminal voltage. The deviation change rate is calculated based on the current control deviation, the control deviation at the previous sampling time, and the 20ms sampling period. The absolute value of the control deviation is divided into three intervals: 0mV to 5mV, 5mV to 20mV, and above 20mV. The absolute value of the deviation change rate is divided into three intervals: 0V / s to 0.1V / s, 0.1V / s to 0.5V / s, and above 0.5V / s. The absolute value of the disturbance compensation is divided into three intervals: 0mV to 10mV, 10mV to 30mV, and above 30mV. The interval boundaries are set by sample statistics. For example, when the 95th percentile control deviation of the stable sample is 5mV, the 95th percentile of the step-switching sample is 20mV, the corresponding deviation change rates are 0.1V / s and 0.5V / s respectively, the 95th percentile disturbance compensation of the stable sample is 10mV, and the 10th percentile of the lithium plating sample is 30mV, the above method is used. Based on the boundary conditions and the matching expert rules for the intervals of the three types of participating items, when the control deviation and the rate of change of deviation have the same sign, the proportional parameter increases by 5%, 10%, and 15% according to the interval of the control deviation, while the integral parameter decreases by 10%, 20%, and 30% respectively. When the signs are opposite, the proportional parameter decreases by 5%, 8%, and 10% respectively, while the derivative parameter increases by 10%, 15%, and 20% respectively. When the disturbance compensation reaches 30mV, the integral parameter is limited to 0.5 times the integral parameter corresponding to the stable sample. For example, when the stable value is 0.8 mV, it is limited to 0.4 mV. The changes in the proportional, integral, and derivative parameters in adjacent cycles are limited to 10%, 10%, and 15% of the current value, respectively. The limiting proportional parameter is the maximum value that has not shown continuous oscillation in 100 step switching calibrations, thus obtaining the adaptive PID parameters.

[0057] In this embodiment, the steps of generating an initial adjustment command based on adaptive PID parameters, determining the requested voltage drop slope based on the initial adjustment command, and limiting the initial adjustment command according to a preset voltage drop slope limit and a preset output boundary are as follows: The control deviation is accumulated over time to obtain the integral state; the requested voltage value is calculated based on the control deviation, integral state, deviation change rate, disturbance compensation amount, and adaptive PID parameters, using the following formula: ,in, This indicates the requested voltage value, in volts. It represents a proportional parameter and is dimensionless. Indicates control deviation, in volts. This represents the integration parameter, in units of seconds. Indicates the integral state, in volt-seconds. This represents the differential parameter, in seconds. This represents the rate of change of deviation, expressed in volts per second. This represents the disturbance compensation amount, in volts; the requested voltage value is used as the initial adjustment command, and the requested descent slope is determined based on the difference between the initial adjustment commands at adjacent sampling times; the voltage descent slope limit and output boundary are determined based on the preset formation power supply calibration data, the requested descent slope is limited within the voltage descent slope limit, and the initial adjustment command is limited within the output boundary, thus obtaining the restricted adjustment command.

[0058] Specifically, the integral state is obtained by accumulating the control deviation according to a 20ms sampling period. The proportional, integral, and derivative parameters are then read. The voltage request value is calculated using discrete PID control and disturbance feedforward compensation, as shown in the formula. ,in, Indicates the first The requested voltage value at each sampling time, in V. Indicates the sampling time sequence number. It represents a proportional parameter and is dimensionless. This represents the control deviation, expressed in V. This represents the integration parameter, in units of seconds. Represents the integral state, with units of V·s. This represents the differential parameter, with units of s. This represents the rate of change of deviation, expressed in V per second. This represents the disturbance compensation amount, in V. The voltage request value is recorded as the initial adjustment command. The requested drop slope is determined based on the difference between the current initial adjustment command and the initial adjustment command at the previous sampling time, and the 20ms sampling period. The drop step data of the formed power supply at 10%, 30%, 50%, 70%, and 90% duty cycles are read. The minimum value among the 10th percentiles of the drop slope for each duty cycle is taken as the voltage drop slope limit. For example, when the five values ​​are 0.42, 0.40, 0.38, 0.36, and 0.35V per second, 0.35V per second is taken. The output boundary is the intersection of the power supply's rated range and the current operating step's allowable range. For example, when the rated range is 0V to 5V and the operating step range is 2.5V to 4.3V, it is set to 2.5V to 4.3V. The requested drop slope is limited to within 0.35V per second, and the initial adjustment command is limited to within 2.5V to 4.3V, resulting in a restricted adjustment command.

[0059] In this embodiment, the steps for identifying lithium plating characteristic disturbances in lumped disturbances and triggering voltage suppression state are as follows: A preset analysis time window corresponding to the lumped disturbance is extracted; mean-reduction processing and discrete spectrum transformation are performed on the lumped disturbance within the analysis time window to obtain the disturbance spectrum; the frequency band energy of the disturbance spectrum within the lithium plating frequency range calibrated by the preset lithium plating cell samples is extracted; the continuous attenuation duration of the terminal voltage within the analysis time window is calculated; when the frequency band energy reaches the preset lithium plating energy threshold, the continuous attenuation duration reaches the preset lithium plating duration threshold, and the absolute value of the difference between the negative voltage value and the preset negative voltage setting value reaches the preset negative voltage deviation threshold, the lumped disturbance within the analysis time window is determined as a lithium plating characteristic disturbance; a suppression flag is written according to the lithium plating characteristic disturbance; the adaptive PID parameters are switched to the suppression parameter group calibrated by the lithium plating cell samples; the suppression compensation coefficient is determined; and the disturbance compensation amount is updated according to the suppression compensation coefficient to trigger voltage suppression state.

[0060] Specifically, the analysis time window is formed by extracting the most recent 5-second lumped disturbance. The 5-second window is taken as the shortest stable decay duration of the lithium plating sample (4.6 seconds), rounded up. The mean-reduced sequence is obtained by subtracting the average value of each lumped disturbance value within the analysis time window. A Fast Fourier Transform is performed on this mean-reduced sequence, and a disturbance spectrum from 0Hz to 25Hz is formed according to a 50Hz sampling frequency corresponding to a 20ms sampling period. The energy concentration frequency bands of the lithium plating samples in the first 10 seconds are statistically analyzed by grouping the samples according to cell type, formation temperature, and charging rate. The overlapping frequency bands of each group are taken as the lithium plating frequency interval. For example, if the three overlapping frequency bands are from 0.8Hz to 1.4Hz, then 0.8Hz to 1.4Hz is used. The square of the amplitude of each frequency point within the lithium plating frequency interval is accumulated to obtain the band energy. The lithium plating energy threshold is taken as the midpoint between the 99th percentile of the band energy of the non-lithium plating stable sample and the 10th percentile of the band energy of the lithium plating sample, for example, 0.018V. The midpoint between the square of 0.026V and 0.022V is 0.022V. The cumulative continuous decay time is when the terminal voltage drops continuously and the single-cycle decrease exceeds 2mV. 2mV is taken as twice the device voltage resolution of 1mV. The lithium plating duration threshold is taken as 90% of the shortest duration of the lithium plating sample, for example, 4.6s multiplied by 0.9 equals 4.14s. The negative voltage deviation threshold is taken as the 99th percentile of the absolute value of the deviation of the stable sample, for example, 3kPa. When the frequency band energy reaches 0.022V, the continuous decay time reaches 4.14s, and the absolute value of the difference between the negative voltage value and the negative voltage setting value reaches 3kPa, the lithium plating characteristic disturbance is determined and written into the suppression flag. The suppression parameter group tuned by the same model, temperature range, and magnification sample is called. The suppression compensation coefficient is taken as the median of the ratio of the terminal voltage decay of the lithium plating sample to the lumped disturbance amplitude, for example, 1.35. The disturbance compensation amount is updated using 1.35, triggering the voltage suppression state.

[0061] In this embodiment, the steps of freezing the integral term state corresponding to the integral parameter and correcting the restricted adjustment command through an anti-saturation tracking differentiator when the restricted adjustment command reaches the output boundary and the requested descent slope exceeds the voltage descent slope limit are as follows: The integral state is read, the initial adjustment command and the restricted adjustment command are compared, and when the initial adjustment command is less than the lower limit of the output boundary and the absolute value of the requested descent slope exceeds the voltage descent slope limit, a restricted descent state is determined; in the restricted descent state, the accumulation of the integral state is stopped, the integral parameter is set to zero, and the integral state before entering the restricted descent state is saved to obtain the frozen integral state; the anti-saturation tracking differentiator generates a back-calculation correction amount based on the difference between the restricted adjustment command and the terminal voltage, and the back-calculation correction amount is superimposed on the restricted adjustment command at the next sampling time; when the initial adjustment command returns to the output boundary and the requested descent slope does not exceed the voltage descent slope limit, the restricted descent state is released, and integral accumulation is resumed according to the frozen integral state.

[0062] Specifically, the process reads the integral state, initial adjustment command, limited adjustment command, output boundary, and requested descent slope. The limiting direction is determined based on the difference between the initial and limited adjustment commands. When the initial adjustment command is lower than the lower limit of the output boundary, it is recorded as downward limiting. The absolute value of the requested descent slope is compared with the voltage descent slope limit. For example, if the initial adjustment command is 2.42V, the lower limit of the output boundary is 2.50V, the absolute value of the requested descent slope is 0.48V / s, and the voltage descent slope limit is 0.35V / s, a descent-limited state is determined. During the corresponding sampling period of the descent-limited state, the accumulation of control deviation stops, the integral parameter is set to 0, and the integral state of the sampling period before entering the descent-limited state is recorded as the frozen integral state (e.g., 0.12V·s). A back-calculation correction is generated based on the difference between the limited adjustment command and the terminal voltage. The difference is multiplied by a back-calculation coefficient, and the back-calculation coefficient is applied... The step calibration setting for the power supply drop is used, and tests are conducted sequentially at values ​​of 0.1, 0.2, 0.3, 0.4, and 0.5. The value with the shortest recovery time and no reverse overshoot is selected from 20 consecutive recoveries. For example, if 0.3 meets the condition, it is set to 0.3. When the restricted regulation command is 2.50V and the terminal voltage is 2.56V, the difference is -0.06V. Multiplying this by 0.3 yields -0.018V. This -0.018V is then added to the restricted regulation command at the next sampling time. When the initial regulation command returns to the range of 2.50V to 4.30V, and the absolute value of the requested drop slope does not exceed 0.35V per second for three consecutive sampling cycles, the drop restriction state is lifted. Three sampling cycles correspond to 60ms. The duration is the number of sampling cycles rounded up from the upper limit of the power supply calibration execution delay of 50ms. After lifting the restriction, the value is accumulated from the frozen integral state of 0.12V·s to obtain the corrected restricted regulation command.

[0063] In this embodiment, the step of generating a micro-sleep command based on the disturbance intensity and polarization growth rate of the lithium plating characteristic disturbance, and controlling the power duty cycle corresponding to the power state to drop to zero within the sleep duration, specifically involves: extracting a preset sleep determination time window corresponding to the lithium plating characteristic disturbance; determining the disturbance intensity based on the difference between the disturbance peak value within the sleep determination time window and the preset lithium plating trigger amplitude; determining the polarization growth rate based on the difference in the attenuation slope of the terminal voltage within two adjacent sleep determination time windows; querying a sleep duration mapping table calibrated by a preset cell model, formation temperature, and rated capacity based on the disturbance intensity and polarization growth rate to obtain the sleep duration, which is between 20 milliseconds and 80 milliseconds; when the disturbance intensity reaches a preset micro-sleep trigger threshold and the polarization growth rate reaches a preset polarization growth threshold, generating a micro-sleep command, reducing the power duty cycle to zero at the next pulse width modulation cycle boundary, and maintaining the power duty cycle at zero within the sleep duration.

[0064] Specifically, the most recent 2-second lithium plating characteristic disturbance is used to form a dormancy determination time window. The 2-second period is taken as the maximum stable response time of 1.6 seconds from 20 dormancy command tests, rounded up. The disturbance intensity is determined based on the difference between the disturbance peak value and the lithium plating trigger amplitude within the dormancy determination time window. The lithium plating trigger amplitude is taken as the 10th percentile of the disturbance peak value of the lithium plating sample. For example, if the peak value is 52mV and the value is 35mV, the disturbance intensity is 17mV. The linear decay slope of the terminal voltage within the current and previous dormancy determination time windows is calculated. The polarization growth rate is determined based on the difference between the two decay slopes. For example, if the previous decay slope was -0.012V / s and the current decay slope is -0.020V / s, the polarization growth rate is 0.008V / s. Historical lithium plating samples are grouped according to cell model, formation temperature range, and rated capacity. Within each group, tests are performed sequentially from 20ms to 80ms with intervals. The sleep duration is 10ms. The voltage drop within 3 seconds after sleep and the maximum reverse deviation during the recovery phase are recorded. The shortest time when the voltage drop reaches the median of the sample and the maximum reverse deviation does not exceed 10mV is taken as the mapping value. For example, if a certain model meets the condition of 50ms under 25℃ to 30℃ and 100Ah conditions, the sleep duration is set to 50ms. 10mV is taken as 10 times the device voltage resolution of 1mV. The micro-sleep trigger threshold is taken as the 10th percentile of the disturbance intensity of the lithium plating sample, for example, 15mV. The polarization growth threshold is taken as the midpoint of 0.004V / s of the 99th percentile of the non-lithium plating sample and 0.006V / s of the 10th percentile of the lithium plating sample, which is 0.005V / s. When the disturbance intensity reaches 15mV and the polarization growth rate reaches 0.005V / s, a micro-sleep command is generated. At the next pulse width modulation cycle boundary, the power supply duty cycle is reduced to 0 and kept at 0 for 50ms.

[0065] In this embodiment, the step of performing disturbance-free recovery after the hibernation period ends and adjusting the formation voltage in a closed loop based on time-series observation data is as follows: at the end of the hibernation period, the terminal voltage is read to obtain the recovery start voltage, the frozen integral term state is read to obtain the recovery integral value; the power supply duty cycle is increased from zero to the duty cycle corresponding to the restricted adjustment command according to the recovery rise slope which is not greater than the preset formation power supply calibration rise slope, and the lumped disturbance is updated through the extended state observer during the increase process; when the absolute value of the difference between the terminal voltage and the restricted adjustment command does not exceed twice the preset device voltage resolution and is maintained for three consecutive sampling cycles, the micro hibernation command is released, the integral accumulation is restored according to the recovery integral value, and disturbance compensation, parameter adjustment, command limiting and lithium plating identification are repeatedly performed according to the time-series observation data until the formation process ends.

[0066] Specifically, at the sampling moment when the sleep duration ends, the terminal voltage is read and recorded as the recovery start voltage, and the frozen integration state is read and recorded as the recovery integration value, for example, 3.72V and 0.10V·s respectively. The 20 rising step calibration data of the formation power supply under the current cell model and current process step are read, and the 10th percentile of the maximum stable rising slope is taken as the formation power supply calibration rising slope. For example, if the 10th percentile is 0.30V / s, then 0.30V / s is used. The recovery rising slope is set according to 80% of the formation power supply calibration rising slope. 80% is determined through four sets of ratio tests: 0.6, 0.7, 0.8, and 0.9. The ratio with the shortest recovery time and no reverse overshoot in 20 consecutive recoveries is taken. For example, if 0.8 meets the condition, the recovery rising slope is set to 0.24V / s. The power supply duty cycle is adjusted according to the duty cycle increment corresponding to 0.24V / s. The duty cycle is incremented from 0 to the corresponding limit regulation command. During the increment, the terminal voltage, charging current, negative voltage, duty cycle, and limit flag are continuously read. The timing observation data is updated, and the lumped disturbance is updated according to the predetermined correction gain of the extended state observer. The device voltage resolution is read from the analog-to-digital conversion accuracy of the formation power supply. For example, when the resolution is 1mV, the recovery judgment range is set to 2mV. When the absolute value of the difference between the terminal voltage and the limit regulation command does not exceed 2mV for three consecutive sampling cycles, the micro-sleep command is released. Three sampling cycles correspond to 60ms, and the duration covers the upper limit of the power supply calibration response delay of 50ms. After release, the recovery integral value of 0.10V·s is used to continue integration and accumulation. The disturbance compensation amount, adaptive PID parameters, limit regulation command, and lithium plating characteristic disturbance are updated according to the timing observation data until the target capacity condition of the current formation step is met, and the continuous closed-loop regulation result is obtained.

[0067] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for forming voltage control based on adaptive PID, characterized in that, Includes the following steps: Collect target voltage trajectory, terminal voltage, charging current, negative voltage value and power state to construct time series observation data. Use the extended state observer to estimate the lumped disturbance composed of the current step corresponding to the charging current, lithium plating polarization and the negative voltage fluctuation corresponding to the negative voltage value, and generate disturbance compensation amount. The control deviation and deviation change rate are calculated based on the target voltage trajectory and the terminal voltage. The adaptive PID parameters of the adaptive PID controller are determined in conjunction with the disturbance compensation amount. The adaptive PID parameters include proportional parameters, integral parameters and derivative parameters. An initial adjustment command is generated based on the adaptive PID parameters. The requested descent slope is determined based on the initial adjustment command. The initial adjustment command is limited according to a preset voltage descent slope limit and a preset output boundary to generate a limited adjustment command. Identify lithium plating characteristic disturbances in the lumped disturbances and trigger a voltage suppression state; When the restricted regulation command reaches the output boundary and the requested descent slope exceeds the voltage descent slope limit, the state of the integral term corresponding to the integral parameter is frozen, and the restricted regulation command is corrected by an anti-saturation tracking differentiator. Based on the disturbance intensity and polarization growth rate of the lithium plating characteristic disturbance, a micro-sleep command is generated to control the power duty cycle corresponding to the power state to drop to zero during the sleep duration. After the specified sleep duration ends, a non-disruptive recovery is performed, and the conversion voltage is adjusted in a closed loop based on the time-series observation data.

2. The formation voltage control method based on adaptive PID according to claim 1, characterized in that, The specific steps for collecting target voltage trajectory, terminal voltage, charging current, negative voltage value, and power state to construct time-series observation data, and using an extended state observer to estimate the lumped disturbance composed of the current step corresponding to the charging current, lithium plating polarization, and negative voltage fluctuation corresponding to the negative voltage value, and generating the disturbance compensation amount are as follows: The target voltage trajectory, terminal voltage, charging current, negative voltage value, duty cycle and limiting flag in the power supply state are collected according to the preset sampling period. Time alignment and range verification are performed to obtain the time series observation data. Based on the time-series observation data, a discrete state relationship of the transformation voltage is established. The step change of the charging current, lithium plating polarization, fluctuation of the negative voltage value and power supply execution error are combined into an extended state. The voltage observation state and disturbance observation state of the extended state observer are updated periodically, and the disturbance observation state is corrected according to the difference between the terminal voltage and the voltage observation state. The observed disturbance state is subjected to low-pass filtering to obtain the lumped disturbance. The lumped disturbance is multiplied by a preset calibration compensation coefficient to obtain the disturbance compensation amount. The single-cycle change of the lumped disturbance is limited to a preset disturbance change threshold.

3. The formation voltage control method based on adaptive PID according to claim 1, characterized in that, The specific steps for calculating the control deviation and deviation change rate based on the target voltage trajectory and the terminal voltage, and determining the adaptive PID parameters of the adaptive PID controller in conjunction with the disturbance compensation amount, are as follows: The control deviation is obtained by subtracting the terminal voltage from the target voltage at the current sampling time. The difference between the control deviations at adjacent sampling times is divided by the preset sampling period to obtain the deviation change rate. According to the absolute value of the control deviation, the absolute value of the rate of change of the deviation, and the absolute value of the disturbance compensation, a preset expert rule is matched. When the control deviation and the rate of change of the deviation have the same sign, the proportional parameter is increased and the integral parameter is decreased. When the control deviation and the rate of change of the deviation have opposite signs, the proportional parameter is decreased and the derivative parameter is increased. When the disturbance compensation amount reaches the preset lithium plating determination boundary, the integral parameter is limited to less than half of the integral parameter corresponding to the preset stable sample without lithium plating, and the changes of the adjusted proportional parameter, integral parameter and derivative parameter in adjacent sampling periods are limited to obtain the adaptive PID parameter.

4. The formation voltage control method based on adaptive PID according to claim 1, characterized in that, The steps of generating an initial adjustment command based on the adaptive PID parameters, determining the requested voltage drop slope based on the initial adjustment command, and limiting the initial adjustment command according to a preset voltage drop slope limit and a preset output boundary to generate a limited adjustment command are as follows: The control deviation is accumulated over time to obtain the integral state. The voltage request value is calculated based on the control deviation, the integral state, the rate of change of the deviation, the disturbance compensation amount, and the adaptive PID parameters, using the following formula: ,in, This indicates the requested voltage value, in volts. The proportional parameter is dimensionless. The control deviation is expressed in volts. This represents the integration parameter, in units of seconds. This indicates the integral state, in volt-seconds. The differential parameter is represented in seconds. This represents the rate of change of the deviation, in volts per second. This represents the disturbance compensation amount, in volts; The requested voltage value is used as the initial adjustment command, and the requested descent slope is determined based on the difference between the initial adjustment commands at adjacent sampling times. The voltage drop slope limit and the output boundary are determined based on the preset formation power supply calibration data. The requested drop slope is limited within the voltage drop slope limit, and the initial adjustment command is limited within the output boundary to obtain the restricted adjustment command.

5. The formation voltage control method based on adaptive PID according to claim 1, characterized in that, The specific steps for identifying lithium plating characteristic disturbances in the lumped disturbances and triggering the voltage suppression state are as follows: A preset analysis time window corresponding to the lumped disturbance is extracted, and mean removal and discrete spectrum transformation are performed on the lumped disturbance within the analysis time window to obtain the disturbance spectrum. The frequency band energy of the disturbance spectrum within the lithium plating frequency range calibrated by the preset lithium plating cell sample is extracted. The continuous decay duration of the terminal voltage within the analysis time window is calculated. When the frequency band energy reaches a preset lithium plating energy threshold, the continuous decay duration reaches a preset lithium plating duration threshold, and the absolute value of the difference between the negative voltage value and the preset negative voltage setting value reaches a preset negative voltage deviation threshold, the lumped disturbance within the analysis time window is determined as the lithium plating characteristic disturbance. Based on the lithium plating characteristic disturbance write suppression flag, the adaptive PID parameters are switched to the suppression parameter group calibrated by the lithium plating cell sample, the suppression compensation coefficient is determined, and the disturbance compensation amount is updated according to the suppression compensation coefficient to trigger the voltage suppression state.

6. The formation voltage control method based on adaptive PID according to claim 4, characterized in that, The specific steps for freezing the state of the integral term corresponding to the integral parameter and correcting the restricted regulation command by an anti-saturation tracking differentiator when the restricted regulation command reaches the output boundary and the requested descent slope exceeds the voltage descent slope limit are as follows: Read the integral state, compare the initial adjustment command with the limited adjustment command, and determine the limited descent state when the initial adjustment command is less than the lower limit of the output boundary and the absolute value of the requested descent slope exceeds the voltage descent slope limit; In the restricted descent state, the accumulation of the integral state is stopped, the integral parameter is set to zero, and the integral state before entering the restricted descent state is saved to obtain the frozen integral state. The anti-saturation tracking differentiator generates a back-calculation correction amount based on the difference between the restricted adjustment command and the terminal voltage. The back-calculation correction amount is superimposed on the restricted adjustment command at the next sampling time. When the initial adjustment command returns to the output boundary and the requested descent slope does not exceed the voltage descent slope limit, the descent restriction state is released, and the integral accumulation is restored according to the frozen integral state.

7. The formation voltage control method based on adaptive PID according to claim 1, characterized in that, The specific steps for generating micro-sleep commands based on the perturbation intensity and polarization growth rate of the lithium plating characteristic perturbation, and controlling the power duty cycle corresponding to the power state to drop to zero during the sleep period, are as follows: A preset dormancy determination time window corresponding to the lithium plating characteristic disturbance is extracted. The disturbance intensity is determined based on the difference between the disturbance peak value within the dormancy determination time window and the preset lithium plating trigger amplitude. The polarization growth rate is determined based on the difference between the attenuation slope of the terminal voltage within two adjacent dormancy determination time windows. The sleep duration is obtained by querying a preset sleep duration mapping table calibrated by cell model, formation temperature and rated capacity based on the disturbance intensity and polarization growth rate. The sleep duration is between 20 milliseconds and 80 milliseconds. When the disturbance intensity reaches a preset micro-sleep trigger threshold and the polarization growth rate reaches a preset polarization growth threshold, the micro-sleep instruction is generated, the power supply duty cycle is reduced to zero at the next pulse width modulation cycle boundary, and the power supply duty cycle is kept at zero during the sleep duration.

8. The formation voltage control method based on adaptive PID according to claim 1, characterized in that, After the sleep duration ends, a disturbance-free recovery is performed, and the conversion voltage is adjusted in a closed loop based on the time-series observation data. The specific steps are as follows: When the sleep duration ends, the terminal voltage is read to obtain the recovery start voltage, and the frozen integral term state is read to obtain the recovery integral value; The duty cycle of the power supply is increased from zero to the duty cycle corresponding to the restricted adjustment command by a recovery rise slope that is not greater than the preset rise slope of the formation power supply calibration, and the lumped disturbance is updated through the extended state observer during the increase process. When the absolute value of the difference between the terminal voltage and the restricted adjustment command does not exceed twice the preset device voltage resolution and is maintained for three consecutive sampling cycles, the micro-sleep command is released, the integral accumulation is restored according to the restored integral value, and the disturbance compensation, parameter adjustment, command limiting and lithium plating identification are repeatedly executed according to the time-series observation data until the formation process ends.

Images