Parallel low-voltage discharging power supply system for battery formation and component distribution

Abstract

The application discloses a parallel low-voltage discharging power supply system for battery formation and component distribution, relates to the field of battery formation and component distribution equipment and power supply control, and comprises a control module and a plurality of parallelly arranged channel branches. Each channel branch comprises a main discharging module, a voltage support module, a switching module, a pulse width modulation driving module, a voltage acquisition module and a current acquisition module. When the port voltage reaches a first trigger threshold, the control module controls the main discharging module to output different set discharging currents in a first sampling period and a second sampling period, so as to determine the path equivalent impedance, and determine the path voltage drop value and the intrinsic cell voltage according to the path equivalent impedance. When the intrinsic cell voltage is not higher than a support starting threshold, the control module controls the voltage support module to output a support voltage. The application solves the problem that the path voltage drop and the real low voltage of the cell are difficult to distinguish in the parallel formation and component distribution low-voltage discharging stage.

Description

Technical Field

[0001] This invention relates to the field of battery formation and capacity control equipment and power supply and distribution control, and more specifically, to a parallel low-voltage discharge power supply system for battery formation and capacity control. Background Technology

[0002] Battery formation and capacity testing are fundamental processes in the later stages of battery manufacturing. In this process, equipment needs to charge, discharge, and acquire data from the batteries under test to complete electrochemical activation, capacity identification, and grouping. Therefore, the equipment typically involves both battery-side charge / discharge control and power supply-side energy conversion and distribution control. Existing technologies in this area generally focus on how energy is transferred between the battery, DC bus, and grid, and how to reduce energy loss and improve system-level operating efficiency. For example, patent CN102709994A, entitled "Bidirectional Power Converter for Electric Vehicle Battery Charge / Discharge," discloses a bidirectional power conversion structure connecting the battery and the grid. The main circuit includes a battery-side filter circuit, a bidirectional DC / DC circuit, a high-frequency isolated DC / DC circuit, a three-phase three-level circuit, and a grid-side filter circuit, managed by a DSP main controller and other control circuits. The focus is on achieving bidirectional energy conversion between the battery and the grid. Another patent, CN112737004A, entitled "A Battery Formation Charging and Discharging Power Supply and Its Formation Method", discloses a formation charging and discharging power supply based on a DC bus, a charging and discharging circuit and a shunt circuit. The current from the discharge of one group of batteries to be formed is supplied to another group of batteries to be formed for charging through the shunt circuit. The key point is to improve energy utilization and reduce the configuration cost of the charging and discharging circuit.

[0003] As can be seen from the above disclosures, existing technologies have addressed the issues of bidirectional conversion, bus reuse, shunt reuse, and energy recovery in formation and capacity testing equipment, and have also been able to improve energy efficiency and equipment utilization at the system level. At the same time, existing technologies also have a clear understanding of the fundamental requirements for formation and capacity testing, namely, the need to control and calculate the voltage, current, and capacity of individual battery cells during charging and discharging.

[0004] However, during the low-voltage discharge stage of parallel capacity testing, a more subtle and easily overlooked problem exists. For a given channel branch, the port voltage actually sampled by the equipment is not entirely equal to the cell's true voltage; it also includes voltage drops from the wiring harness, clamps, contacts, switching devices, and conductive paths. When the battery under test enters the tail end of the low-voltage phase, especially when the voltage is already low, the discharge current still exists, and the contact states of different channel branches are not entirely consistent, this path voltage drop will be significantly amplified. In layman's terms, the equipment may superficially see "this channel voltage is too low," but part of this low voltage may not originate from the cell itself, but rather from the channel path itself. Consequently, the system may easily mistake "false low voltage from the path" for "the cell itself being too low." This misjudgment directly affects subsequent low-voltage discharge power supply decisions, causing some channels to prematurely enter the support state, while other channels that truly require support may not be accurately identified.

[0005] This pain point has been easily overlooked for a long time because existing technologies mostly focus on high-power conversion structures, energy feedback paths, DC bus organization, and energy reuse among multiple battery banks, assuming that the port voltage acquired at the front end is sufficient to represent the state of the battery under test. On the other hand, the low-voltage tail section usually occupies a short time in a single process, and the problem only comes to light when there is deep discharge, before and after the intervention of low-voltage support, when there are large differences in channel impedance, or when there are many parallel stations. Therefore, it is not easy to become the first contradiction to be seen in general system-level design. Existing public technologies address more the issues of "how energy flows," "how power is distributed," and "how the system saves power," while rarely delving into the more critical issue of "how to distinguish whether the low voltage at the port comes from the cell or from the path"—a problem closer to the precision of single-channel control. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a parallel low-voltage discharge power supply system for battery formation and capacity control, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A parallel low-voltage discharge power supply system for battery formation and capacity testing includes a control module and multiple parallel channel branches. Each channel branch is used to connect a battery under test. Each channel branch includes a main discharge module, a voltage support module, a switching module, a pulse width modulation drive module, a voltage acquisition module, and a current acquisition module.

[0009] The control module is used to control the main discharge module to output a first set discharge current during the first sampling period and a second set discharge current during the second sampling period when the port voltage collected by the voltage acquisition module reaches the first trigger threshold. The control module is also used to determine the path equivalent impedance of the channel branch based on the first port voltage corresponding to the first sampling period, the second port voltage corresponding to the second sampling period, the first set discharge current, and the second set discharge current.

[0010] The control module is also used to determine the path voltage drop value based on the path equivalent impedance and the working discharge current, determine the intrinsic cell voltage based on the port voltage and the path voltage drop value, and when the intrinsic cell voltage is not higher than the support start-up threshold, control the switching module to connect the voltage support module in series between the battery under test and the main discharge module, so that the channel branch enters the support state, and control the voltage support module to output the support voltage.

[0011] Preferably, each of the channel branches further includes a battery interface, and the switching module is disposed between the battery interface and the main discharge module;

[0012] The switching module is used to bypass the voltage support module in the first state and connect the voltage support module in series between the battery interface and the main discharge module in the second state.

[0013] Preferably, the first sampling period and the second sampling period are located within the same identification cycle, and the first set discharge current is greater than the second set discharge current;

[0014] The control module is used to divide the difference between the first port voltage and the second port voltage by the difference between the first set discharge current and the second set discharge current to determine the path equivalent impedance.

[0015] Preferably, the control module is used to determine the path voltage drop value by multiplying the path equivalent impedance and the working discharge current, and to determine the intrinsic cell voltage by the difference between the port voltage and the path voltage drop value.

[0016] Preferably, the control module is configured to determine the support voltage based on the difference between the target port voltage and the intrinsic cell voltage, and during the period when the channel branch is in the support state, redetermine the intrinsic cell voltage according to the update cycle, and update the support voltage based on the redetermined intrinsic cell voltage.

[0017] Preferably, the control module is used to control the voltage support module to enter the unsupported observation window according to the observation cycle during the period when the channel branch is in the supported state, and to collect the natural terminal voltage in the unsupported observation window, and to collect the recovery terminal voltage after the unsupported observation window ends.

[0018] Preferably, the control module is used to control the support level and discharge cutoff of the channel branch according to the natural terminal voltage and the recovery terminal voltage;

[0019] The control module is also used to switch the current support level to a lower support level when the natural terminal voltage is higher than the support holding threshold, and to control the main discharge module to stop discharging when the natural terminal voltage is not higher than the cutoff judgment threshold and the difference between the recovery terminal voltage and the natural terminal voltage is not lower than the rebound judgment threshold.

[0020] Preferably, the control module is used to allocate different phase offsets to each channel branch in the support state according to the number of channel branches in the support state when multiple channel branches are in the support state at the same time, and control each pulse width modulation driving module to drive the corresponding voltage support module according to the corresponding phase offset.

[0021] Preferably, the control module is used to distribute the multiple phase offsets at equal intervals to multiple channel branches in the supported state within one carrier cycle, and to reallocate the phase offsets in the next phase update cycle when the number of channel branches in the supported state changes.

[0022] Preferably, the control module is used to set a valley sampling window for each channel branch in the supported state, and output a sampling trigger signal to each voltage acquisition module so that each voltage acquisition module can acquire port voltage within the valley sampling window of the corresponding channel branch.

[0023] The control module is also used to perform support voltage control and discharge cutoff control on the corresponding channel branch based on the port voltage collected in the valley sampling window.

[0024] The advantages of this invention over the prior art are:

[0025] The core beneficial effect of this invention is based on a clear technical principle: within the same channel branch, the path voltage drop changes with the discharge current, while the intrinsic cell voltage of the battery under test remains relatively stable within the same identification period. Therefore, this invention does not directly determine that the battery under test has entered a low-voltage state requiring support when the port voltage drops. Instead, it first sets a first sampling period and a second sampling period within the same identification period, causing the main discharge module to output a first set discharge current and a second set discharge current respectively. Then, based on the port voltage changes during the two sampling periods, it determines the equivalent impedance of the path, and subsequently determines the path voltage drop and the intrinsic cell voltage. In this way, the system can first isolate the influence of the channel path on the port voltage before deciding whether to allow the voltage support module to intervene, thus avoiding the problem of misjudging the path voltage drop as the cell's own low voltage. Consequently, the timing of low-voltage discharge power supply intervention is more accurate, and the control basis of a single channel branch at the end of the low-voltage phase is closer to the actual state of the battery under test.

[0026] In a further technical arrangement, this invention utilizes the principle that the battery under test will exhibit a natural terminal voltage after the support is weakened or removed, and will form a recovered terminal voltage after the support is restored. While the channel branch is in the supported state, a support removal observation window is periodically set, and the natural terminal voltage is collected within the support removal observation window. After the support removal observation window ends, the recovered terminal voltage is collected, allowing continued observation of the battery under test's true performance without support coverage. This not only allows for step-by-step adjustment of the current support level but also enables a more reliable determination of whether discharge should be cut off in the low-voltage tail end, avoiding reliance solely on the apparent port voltage under the supported state. Thus, a continuous judgment chain is formed between support control and cutoff control, resulting in smoother control in the low-voltage tail end and cutoff judgments that more closely reflect the battery under test's actual state.

[0027] When multiple channel branches are simultaneously in a supported state, this invention also utilizes another technical principle: if multiple pulse width modulation drive signals are too concentrated in time, ripple will superimpose and interfere with port voltage sampling. By assigning different phase offsets to different channel branches and sampling within their respective valley sampling windows, the judgment deviation caused by sampling jitter can be reduced. Based on this principle, this invention performs phase-shift control on the pulse width modulation drive of each channel branch under multi-channel support conditions, and combines this with the valley sampling window output sampling trigger signal, so that support voltage control and discharge cutoff control are based on more stable sampling data. This can further reduce mutual interference when the number of parallel stations increases and improve the control consistency when multiple channels are running simultaneously. Attached Figure Description

[0028] Figure 1 is the overall architecture diagram of the parallel low-voltage discharge power supply system;

[0029] Figure 2This is the main flowchart of the core control logic of the control module of this invention;

[0030] Figure 3 is a timing diagram of the action mechanism of the support removal observation window and the voltage acquisition of the present invention;

[0031] Figure 4 This is the timing diagram of phase offset control when the multi-channel branch is supported in parallel according to the present invention;

[0032] Figure 5 This is a conceptual diagram of the physical equipment and its actual installation according to the present invention;

[0033] Figure 6 This is a timing diagram of the valley-level synchronous sampling mechanism based on PWM carrier of the present invention. Detailed Implementation

[0034] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0035] This implementation revolves around a complete control chain. The control chain first identifies the current low-voltage state of the battery under test, distinguishing whether the low voltage state is caused by path voltage drop in a channel branch or by the battery itself entering a low-voltage range. After identifying that the battery under test has entered a low-voltage range requiring support, the voltage support module participates in discharging and supplying power. After the voltage support module has participated in discharging and supplying power, the natural terminal voltage and recovery terminal voltage of the battery under test are obtained through the support removal observation window to control the support level and discharge cutoff. When multiple channel branches simultaneously enter the support state, phase offset allocation and valley sampling window settings ensure sampling consistency and control consistency across multiple channel branches in the support state. The entire technical solution revolves around the same hardware structure and the same control module, with each part logically connected sequentially, rather than being independent, isolated modules.

[0036] As shown in Figures 1 and 5, the parallel low-voltage discharge power supply system in this embodiment includes a control module and multiple parallel channel branches. These channel branches are connected to the system's bus side. While structurally independent, each channel branch is managed by the same control module. Each channel branch connects to one battery under test (DUT), allowing multiple DUTs to perform the discharge process in the formation and capacity testing stage in parallel on the same device. Since the formation and capacity testing process often requires processing a large number of DUTs simultaneously, and the voltage drop rate, polarization state, and connection state of each DUT are inconsistent, assigning each DUT to a different channel branch facilitates independent identification and control of each channel.

[0037] Each channel branch includes a battery interface, a main discharge module, a voltage support module, a switching module, a pulse width modulation (PWM) drive module, a voltage acquisition module, and a current acquisition module. The battery interface is used to establish an electrical connection with the battery under test. The battery interface can be a clamp interface, a probe interface, or a plug-in interface, as long as it can stably connect to the battery under test in the formation and capacity testing equipment. In this embodiment, the battery interface is connected to the input side of the switching module, the output side of the switching module is connected to the main discharge module, the voltage support module is connected to the switching module, the PWM drive module is connected to the voltage support module, and the voltage acquisition module and current acquisition module are respectively connected to the control module.

[0038] A switching module is positioned between the battery interface and the main discharge module to switch whether the voltage support module is connected to the main discharge path of the channel branch under different operating conditions. The switching module has a first state and a second state. In the first state, the switching module bypasses the voltage support module. In this state, the battery under test directly forms a discharge circuit with the main discharge module via the battery interface and the switching module. The voltage support module does not participate in the output, and the channel branch is in a non-supported state. In the second state, the switching module connects the voltage support module in series between the battery interface and the main discharge module. In this state, the discharge path between the battery under test and the main discharge module includes the voltage support module, and the channel branch is in a supported state. The reason for setting up the switching module is that this invention does not continuously allow the voltage support module to work throughout the entire discharge process. Instead, it first determines whether it is necessary to enter the supported state through an identification process, and then connects the voltage support module when necessary, to avoid the voltage support module participating too early, which could affect the judgment of the intrinsic cell voltage.

[0039] The main discharge module is used to perform discharge according to the working discharge current issued by the control module. The main discharge module can adopt a controllable electronic load structure or a discharge working unit in a bidirectional conversion circuit, as long as it can stably output different levels of discharge current under the control of the control module. In this embodiment, the main discharge module can output at least a first set discharge current and a second set discharge current during the identification phase, and can output the working discharge current during the normal discharge phase. The current control resolution of the main discharge module is preferably higher than the current accuracy requirements of the formation and capacity testing process, thereby ensuring that the identification results of the path equivalent impedance and intrinsic cell voltage have sufficient reliability.

[0040] The voltage support module outputs a support voltage after a channel branch enters the support state. The voltage support module can employ a boost converter circuit, an isolated DC-DC converter circuit, or a non-isolated DC-DC converter circuit. In this embodiment, the voltage support module is driven by a pulse width modulation (PWM) driver module. The PWM driver module outputs a PWM drive signal to the voltage support module to control its switching action, duty cycle, and phase offset. Using a PWM driver module instead of a fixed output method allows the voltage support module to not only output different support voltages according to the control module's instructions but also to perform phase offset distribution control when multiple channel branches are simultaneously in the support state.

[0041] The voltage acquisition module is used to acquire the port voltage of the channel branch. Here, port voltage refers to the voltage measured at the connection point between the battery under test and the channel branch under the current control state. The current acquisition module is used to acquire the actual discharge current in the discharge path where the main discharge module is located. Both the voltage and current acquisition modules are connected to the control module so that the control module can perform identification, support, and cutoff control based on the real-time sampling results. The voltage acquisition module is preferably located near the battery interface to reflect the voltage state at the battery port as accurately as possible. The current acquisition module is preferably located on the input or output side of the main discharge module, as long as it can uniquely characterize the discharge current in the channel branch.

[0042] As shown in Figure 2, the control module executes the entire control process. The control module can employ an industrial controller, embedded processor, digital signal processor, or a combination of a field-programmable gate array (FPGA) and a microprocessor. Internally, the control module may include a sampling management unit, a support determination unit, a support control unit, an observation control unit, and a phase scheduling unit. The sampling management unit receives sampling data from the voltage and current acquisition modules. The support determination unit calculates the path equivalent impedance, path voltage drop, and intrinsic cell voltage, and determines whether to enter the support state based on the intrinsic cell voltage. The support control unit generates a target support voltage and adjusts the current support level after the channel branch enters the support state. The observation control unit inserts a disengagement observation window during the support state and determines support level adjustment and discharge cutoff based on the natural terminal voltage and the recovery terminal voltage. The phase scheduling unit allocates phase offsets when multiple channel branches are simultaneously in the support state and sets valley sampling windows for each channel branch.

[0043] In this embodiment, the control module first monitors the port voltage when the channel branch is in a non-supported state. The so-called first trigger threshold is the trigger condition for the start of identification control. This first trigger threshold can be set as the upper boundary value of the low-voltage discharge stage in the formation and capacity testing process, or it can be set as a predicted value slightly higher than the support start threshold. The reason for adopting this setting is that the system needs to complete the judgment of the path equivalent impedance and intrinsic cell voltage before the battery under test actually enters the supported state. If the identification is started after the battery under test has reached its limit, it may not be possible to complete the stable identification process in time. Therefore, when the port voltage reaches the first trigger threshold, the control module does not immediately allow the channel branch to enter the supported state, but instead first causes the channel branch to enter the identification cycle.

[0044] The identification period includes a first sampling period and a second sampling period. The first and second sampling periods are located within the same identification period, preferably consecutively or after a very short switching interval. This arrangement aims to ensure that the changes in the state of charge, temperature, and polarization of the battery under test remain as consistent as possible within these two sampling periods, so that the voltage difference between the two periods primarily reflects the path voltage drop difference of the channel branch, rather than a significant change in the battery itself. A first set discharge current is greater than a second set discharge current. The control module controls the main discharge module to output the first set discharge current during the first sampling period and the second set discharge current during the second sampling period. The voltage acquisition module acquires the first port voltage and the second port voltage during these two sampling periods, respectively, while the current acquisition module simultaneously verifies whether the actual current values ​​during the two sampling periods reach the first and second set discharge currents, respectively.

[0045] In one implementation, the control module reads the first port voltage at a stable sampling point after the start of the first sampling period, and reads the second port voltage at a stable sampling point after the start of the second sampling period. A stable sampling point refers to the sampling moment after the main discharge module has completed current switching and the transient disturbance at the battery under test port has subsided. The significance of setting stable sampling points is to avoid incorporating peaks or troughs at the switching instant into the path equivalent impedance calculation. The duration of the first and second sampling periods can be determined based on the device's sampling capability and the time constant of the battery under test, as long as the voltage and current within the corresponding periods enter the stable sampling range.

[0046] The control module determines the path equivalent impedance of the channel branch based on the first port voltage, the second port voltage, the first set discharge current, and the second set discharge current. Specifically, the control module divides the difference between the first port voltage and the second port voltage by the difference between the first set discharge current and the second set discharge current to obtain the path equivalent impedance. This path equivalent impedance characterizes the equivalent resistance to current changes along the entire discharge path from the battery under test to the main discharge module. This path equivalent impedance includes not only the impedance of the connecting harness but also the combined effects of the connecting clamps, contacts, relay conduction paths, switching module conduction paths, printed circuit board wires, and other series conductive parts. The reason for using the path equivalent impedance parameter, rather than simply assuming a fixed discharge path, is that during long-term operation of the formation and capacity testing equipment, different channel branches may have different path states due to contact wear, oxidation, and changes in crimping conditions. If this difference is ignored, directly judging whether the battery under test needs support based solely on the port voltage would misjudge a case of excessive path voltage drop as a case where the battery under test itself is too low.

[0047] More specifically, the path equivalent impedance characterizes the incremental impedance of the conductive path in the channel branch in response to changes in discharge current within the same identification period. During the first and second sampling periods, due to the short sampling time, the state changes of the battery under test are relatively small, and the intrinsic voltage of the battery under test within this identification period can be considered approximately constant. At this time, the port voltage, discharge current, and path equivalent impedance satisfy the following approximate relationship:

[0048] ;

[0049] in, Indicates the port voltage. This indicates the intrinsic voltage of the battery under test within the current identification period. Indicates the discharge current. Indicates the path equivalent impedance;

[0050] Furthermore, let This represents the first port voltage corresponding to the first sampling period. This represents the second port voltage corresponding to the second sampling period. This indicates the first set discharge current corresponding to the first sampling period. Let the second set discharge current corresponding to the second sampling period be:

[0051] ;

[0052] Subtracting the two equations above, we get:

[0053] ;

[0054] Therefore, we can conclude that:

[0055] ;

[0056] Due to the first set discharge current Greater than the second set discharge current Therefore, the above expression can also be written as:

[0057] .

[0058] Based on the above relationship, the control module determines the path equivalent impedance by using the difference between the first port voltage and the second port voltage, and the difference between the first set discharge current and the second set discharge current. The path equivalent impedance characterizes the path voltage drop characteristics of the current channel branch under current connection and discharge conditions caused by current changes, and serves as the basis for subsequently determining the path voltage drop value and the intrinsic cell voltage.

[0059] After obtaining the path equivalent impedance, the control module determines the path voltage drop value based on the path equivalent impedance and the operating discharge current. The operating discharge current refers to the actual discharge current value performed by the main discharge module for the battery under test at the current process stage. In one embodiment, the control module determines the path voltage drop value as the product of the path equivalent impedance and the operating discharge current. This path voltage drop value characterizes how much voltage is consumed by the connection path of the channel branch under the current operating discharge current conditions. The control module then determines the intrinsic cell voltage based on the port voltage and the path voltage drop value. Specifically, the control module subtracts the path voltage drop value from the port voltage to obtain the intrinsic cell voltage. The intrinsic cell voltage characterizes the cell's own voltage level after deducting the influence of the channel branch path voltage drop.

[0060] The direct purpose of setting the intrinsic cell voltage is to isolate the influence of the channel branch path state before the critical control action of entering the support state. This way, when a channel branch has a low port voltage due to a large equivalent impedance, the system will not simply enter the support state based on the superficially observed port voltage. Instead, it will further determine whether the intrinsic cell voltage of the battery under test has truly reached the support start-up threshold. Only when the intrinsic cell voltage is not higher than the support start-up threshold will the control module control the switching module to enter the second state, connecting the voltage support module in series between the battery under test and the main discharge module, thus putting the channel branch into the support state and controlling the voltage support module to output the support voltage.

[0061] In one implementation, the support activation threshold is set to the low-voltage support entry boundary value allowed by the formation capacity discharge process. This value can be predetermined by the process and stored in the control module. When comparing the intrinsic cell voltage with the support activation threshold, the control module can either set a single judgment mechanism or perform a switch only after multiple consecutive consistent judgments, to avoid erroneous switching caused by sampling noise. As long as the control logic always revolves around the intrinsic cell voltage, rather than directly around the port voltage, the core control concept of this invention can be maintained.

[0062] Once the channel branch enters the support state, the control module needs to further determine the support voltage. The support voltage is not a fixed, constant value, but is determined by the control module based on the difference between the target port voltage and the intrinsic cell voltage. The target port voltage is the target voltage level that the system aims to maintain at the input of the main discharge module or the port of the battery under test during the current discharge phase. This is because the role of the voltage support module is not to replace the battery under test in bearing all the output, but rather to supplement the difference when the intrinsic cell voltage of the battery under test is insufficient to maintain the target port voltage. The control module generates a target support voltage based on the difference between the target port voltage and the intrinsic cell voltage, and sends this target support voltage to the pulse width modulation (PWM) drive module. The PWM drive module then adjusts the duty cycle and switching action of the voltage support module to ensure that the voltage support module outputs a support voltage corresponding to the target support voltage.

[0063] During the support state, the intrinsic cell voltage is not static. As discharge continues, the polarization state, internal reaction state, and remaining capacity state of the battery under test all change. Therefore, the control module does not determine the support voltage once and keep it unchanged, but rather redetermines the intrinsic cell voltage according to the update cycle and updates the support voltage based on the redetermined intrinsic cell voltage. The update cycle can be the same as, shorter than, or longer than the identification cycle. As long as the control module obtains a sufficiently reliable intrinsic cell voltage again within each update cycle, it can dynamically correct the support voltage. The significance of adopting the update cycle mechanism is to avoid the support voltage from remaining fixed for a long time after the channel branch enters the support state, thereby causing over-support or under-support.

[0064] As shown in Figure 3, to continue obtaining information related to the true state of the battery under test while in the supported state, this embodiment introduces a support removal observation window. During the period when the channel branch is in the supported state, the control module controls the voltage support module to enter the support removal observation window according to the observation cycle, and collects the natural terminal voltage within the support removal observation window. After the support removal observation window ends, it collects the recovered terminal voltage. The support removal observation window refers to the control module temporarily reducing or removing the output of the voltage support module in the supported state, allowing the battery under test to expose its terminal voltage change characteristics in a near-natural state for a short and controllable time interval. The reason for introducing the support removal observation window is that in the continuous supported state, the port voltage is directly affected by the output of the voltage support module. If the support is not temporarily removed or reduced, the control module will find it difficult to determine whether the battery under test still has sufficient discharge capacity, and also difficult to determine whether the battery under test has reached the true discharge cutoff condition.

[0065] In one implementation, the observation period is uniformly set by the control module. When the channel branch is in a supported state for the set observation period duration, the control module initiates a support removal observation window. At the start of the support removal observation window, the control module lowers the current support level to the observation support level. The observation support level can be set to zero or a preset low value lower than the current support level. In the implementation where the observation support level is set to zero, the voltage support module completely stops providing support to the channel branch within the support removal observation window; therefore, the natural terminal voltage collected at this time can more directly reflect the state of the battery under test under the current discharge conditions. In the implementation where the observation support level is set lower than the current support level, the natural degradation trend of the battery under test can be observed without completely removing the support. Regardless of the method used, as long as the voltage collected within the support removal observation window can be distinguished from the port voltage in the supported state, it constitutes the natural terminal voltage described in this invention.

[0066] The control module acquires the natural terminal voltage within the support removal observation window and the recovered terminal voltage after the support removal observation window ends. The natural terminal voltage is the terminal voltage of the battery under test after the support is weakened or removed, and the recovered terminal voltage is the terminal voltage acquired after the voltage support module returns to the current support level. In one embodiment, the control module can acquire the natural terminal voltage in the middle or later part of the support removal observation window to avoid the voltage jump caused by the instantaneous switching of support voltage; and acquire the recovered terminal voltage after a short stabilization period after the support is restored to ensure that the recovered terminal voltage truly reflects the port state after the support is restored.

[0067] The control module controls the support level and discharge cutoff of the channel branch based on the natural terminal voltage and the recovery terminal voltage. The support level is the support output level currently assigned to the voltage support module by the control module. In one implementation, the control module internally stores multiple sequentially decreasing support levels and switches the current support level among these levels progressively while the channel branch is in a supported state. When the natural terminal voltage is higher than the support holding threshold, it indicates that under the current discharge stage, even if the support is temporarily weakened or removed, the battery under test can still maintain a high natural voltage level. At this time, the control module switches the current support level to a lower support level. This progressive reduction method, rather than a complete withdrawal of support all at once, is used to make the support process smoother and to allow the battery under test a gradual recovery process to its natural discharge dominance.

[0068] Meanwhile, the control module also determines whether to stop discharging based on the natural terminal voltage and the recovered terminal voltage. In one implementation, when the natural terminal voltage is not higher than the cutoff threshold and the difference between the recovered terminal voltage and the natural terminal voltage is not lower than the rebound threshold, the control module controls the main discharge module to stop discharging. The control logic here can be understood as two layers of constraints. The first constraint requires that the battery under test has already shown a low natural terminal voltage within the support removal observation window, and the second constraint requires that there is a sufficient rebound difference between its port voltage and the natural terminal voltage after support is restored. A low natural terminal voltage indicates that the battery under test itself can hardly continue to maintain discharge at the current process stage; a large difference between the recovered terminal voltage and the natural terminal voltage indicates that the port voltage after recovery mainly depends on the support provided by the voltage support module, rather than from the battery under test itself. When both conditions are met simultaneously, the control module determines that the channel branch has reached the discharge cutoff condition and stops the discharge operation of the main discharge module. The significance of this setting is that the discharge cutoff judgment is based on the comparison between the performance of the battery under test itself and its performance after support, rather than being determined solely by the apparent port voltage in the supported state.

[0069] When multiple channel branches are simultaneously in the supported state, this embodiment further considers the sampling interference problem caused by the parallel operation of multiple voltage support modules. Since each voltage support module is driven by its own pulse width modulation (PWM) driver module, if multiple channel branches enter the supported state simultaneously and their respective PWM driver signals overlap in time, the switching actions of multiple channel branches in the system may occur synchronously, resulting in increased ripple on the bus side and at local measurement points, thereby affecting the stability of port voltage sampling. To address this, when multiple channel branches are simultaneously in the supported state, the control module assigns different phase offsets to each channel branch in the supported state according to the number of channel branches in the supported state, and controls each PWM driver module to drive the corresponding voltage support module according to the corresponding phase offset.

[0070] The phase offset here refers to the relative starting position offset of the pulse width modulation drive signals of different channel branches within the same carrier cycle. The control module can maintain a support state channel list. When a channel branch enters the support state, the control module adds that channel branch to the support state channel list; when a channel branch exits the support state, the control module removes that channel branch from the support state channel list. The phase scheduling unit recalculates the phase offset for each channel branch based on the number of channels in the support state channel list, thereby ensuring that multiple channel branches simultaneously in the support state do not all perform switching actions at the same time.

[0071] In one implementation, the control module distributes multiple phase offsets at equal intervals to multiple channel branches in the supported state within one carrier cycle. The equal interval method means dividing one carrier cycle into multiple time intervals based on the number of channel branches in the supported state, with each channel branch corresponding to the start or center phase of one of these time intervals. The purpose of using the equal interval method is to evenly distribute the switching actions of multiple channel branches along the time axis, thereby reducing the superposition of switching at the same moment. As a result, when multiple channel branches are simultaneously in the supported state, the overall ripple peak value is more easily weakened, and the port voltage sampling environment of each channel branch is more stable.

[0072] As shown in Figure 4, when the number of channel branches in the support state changes, the control module reallocates the phase offset in the next phase update cycle. The reason for not reallocating immediately upon the change in number, but rather uniformly in the next phase update cycle, is to avoid the phase allocation change and support state switching occurring simultaneously, thus preventing overly dense transient control. The phase update cycle can be set by the control module based on the carrier cycle of the pulse width modulation drive module, as long as the updating of the phase offset and the switching of the drive states of each channel branch are carried out in an orderly manner.

[0073] As shown in Figure 6, after completing the phase offset allocation, the control module further sets a valley sampling window for each channel branch in the supported state and outputs a sampling trigger signal to each voltage acquisition module, so that each voltage acquisition module can acquire the port voltage within the valley sampling window of the corresponding channel branch. The valley sampling window refers to a time window during which the voltage ripple is relatively small or relatively stable within the pulse width modulation drive cycle of the corresponding channel branch. This time window corresponds one-to-one with the phase offset of the corresponding channel branch. Since the pulse width modulation drive signals of different channel branches have different phase offsets, the valley sampling windows of different channel branches are also different in absolute time. The control module needs to calculate the valley sampling window of each channel branch based on its phase offset and send a sampling trigger signal to the corresponding voltage acquisition module.

[0074] The significance of using a valley sampling window for port voltage sampling lies in the fact that the port voltage in the supported state is not an ideal DC quantity, but rather superimposed with ripple generated by pulse width modulation. If the sampling timing is not controlled, the voltage acquisition module may sample the port voltage at the ripple peak, ripple transition section, or the moment of switch switching, resulting in significant fluctuations in the sampling results between different sampling periods. This ultimately affects the judgment of intrinsic cell voltage, supported voltage, and discharge cutoff. By setting a valley sampling window for each channel branch in the supported state, the control module can ensure that the port voltage sampling falls more concentratedly within the time period of relatively stable ripple, thereby improving the consistency of subsequent control judgments.

[0075] The control module performs support voltage control and discharge cutoff control on the corresponding channel branches based on the port voltage collected within the valley sampling window. This means that when multiple channel branches are simultaneously in a supported state, the aforementioned controls regarding support voltage updates, support removal observation windows, natural end voltage acquisition, recovery end voltage acquisition, support level switching, and discharge cutoff determination are not executed independently of the valley sampling window, but are all based on the more stable sampling values ​​provided by the valley sampling window. In other words, the valley sampling window provides a unified data foundation for all key voltage determinations in the supported state, while the phase offset allocation provides a prerequisite for the stable existence of the valley sampling window.

[0076] The following further explains the operation of the entire control process within a complete discharge cycle. After the battery under test is connected to the corresponding channel branch through the battery interface, the control module first puts the switching module in the first state. At this time, the voltage support module is bypassed, and the main discharge module performs a normal discharge of the battery under test according to the formation and capacity testing requirements. The voltage acquisition module continuously acquires the port voltage, and the current acquisition module continuously acquires the working discharge current. When the port voltage reaches the first trigger threshold, the control module does not immediately enter the support state, but instead starts the identification cycle. During the identification cycle, the main discharge module outputs the first set discharge current and the second set discharge current in sequence, and the voltage acquisition module acquires the first port voltage and the second port voltage. The control module determines the path equivalent impedance based on this, and then determines the path voltage drop value by combining it with the working discharge current, and obtains the intrinsic cell voltage accordingly.

[0077] If the intrinsic cell voltage is higher than the support start-up threshold, the control module determines that the current port voltage drop is mainly caused by path voltage drop, the channel branch remains in a non-supported state, and the main discharge module continues to discharge according to the process. The control module continues to monitor the port voltage in subsequent update cycles and can restart the identification cycle. If the intrinsic cell voltage is not higher than the support start-up threshold, the control module determines that the battery under test has entered the low voltage range that requires support, and then controls the switching module to enter the second state, connecting the voltage support module in series between the battery under test and the main discharge module, and generating a support voltage target based on the difference between the target port voltage and the intrinsic cell voltage. The pulse width modulation drive module drives the voltage support module to output the support voltage.

[0078] While the channel branch is in the supported state, the control module, on the one hand, re-determines the intrinsic cell voltage and updates the support voltage according to the update cycle, ensuring that the support output matches the current state of the battery under test; on the other hand, it inserts a support removal observation window according to the observation cycle, acquiring the natural terminal voltage within the support removal observation window and the recovery terminal voltage after the support removal observation window ends. If the natural terminal voltage is higher than the support maintenance threshold, the control module switches the current support level to a lower support level to weaken the support strength. If the natural terminal voltage is not higher than the cutoff judgment threshold, and the difference between the recovery terminal voltage and the natural terminal voltage is not lower than the rebound judgment threshold, the control module stops the discharge operation of the main discharge module, completing the discharge cutoff of the battery under test in the current process stage.

[0079] If multiple channel branches enter the support state simultaneously, the control module registers these channel branches in the support state channel list and assigns different phase offsets to each channel branch according to the number in the list. This allows each pulse width modulation drive module to drive the corresponding voltage support module with different timing sequences. Subsequently, the control module sets a valley sampling window based on the phase offset of each channel branch and causes each voltage acquisition module to acquire the port voltage within the corresponding valley sampling window. Therefore, even if multiple channel branches are in the support state simultaneously, support voltage updates and discharge cutoff determination can be performed under relatively stable measurement conditions.

[0080] To further refine the logical relationships, in this embodiment, the first trigger threshold, support initiation threshold, support holding threshold, cutoff determination threshold, and rebound determination threshold are preferably pre-stored in the control module and can be configured separately according to different battery types and different formation and capacity testing stages. The first trigger threshold is higher than the support initiation threshold and is used to trigger the identification cycle in advance. The support holding threshold is higher than the cutoff determination threshold and is used to distinguish between two different control actions: support level drop and discharge cutoff. The rebound determination threshold is used to characterize the degree of increase in port voltage relative to the natural terminal voltage after support recovery; the larger this value, the more the recovered port voltage depends on the voltage support module. Through the hierarchical relationship between these thresholds, the control module can orderly realize identification, support, degraded support, and cutoff control within the same structure.

[0081] In one embodiment, to adapt the control parameters to the low-voltage discharge conditions during the battery formation and capacity assembly stage, the first trigger threshold can be set to 0.8V to 2.5V, the support start threshold can be set to 0.5V to 2.2V, and the first trigger threshold is 0.05V to 0.4V higher than the support start threshold. The support hold threshold can be set to 0.6V to 2.4V, the cutoff determination threshold can be set to 0V to 1.0V, and the support hold threshold is 0.1V to 1.2V higher than the cutoff determination threshold. The rebound determination threshold can be set to 0.02V to 0.5V, used to characterize the recovery magnitude of the port voltage relative to the natural terminal voltage after support is restored. The target port voltage can be set to 1.0V to 3.0V, and the support voltage can be set to 0V to 2.0V. The first set discharge current can be set to 0.5A to 20A, the second set discharge current can be set to 0.1A to 15A, and the first set discharge current is 0.1A to 10A higher than the second set discharge current. The duration of both the first and second sampling periods can be set to 10ms to 500ms, and the switching interval between two adjacent sampling periods can be set to 1ms to 50ms. The update cycle can be set to 50ms to 5s, the observation cycle can be set to 0.5s to 60s, and the duration of the support removal observation window can be set to 10ms to 500ms. The observation support level can be set to 0V to 80% of the current support level to expose the natural terminal voltage characteristics of the battery under test within the support removal observation window. The carrier frequency of the pulse width modulation drive module can be set to 20kHz to 1000kHz, the phase update cycle can be set to 1 carrier cycle to 200 carrier cycles, and the duration of the valley sampling window can be set to 5% to 30% of a single carrier cycle. For batteries under test with different material systems, different rated capacities, and different formation and capacity testing processes, the above parameter ranges can be configured separately by the control module by calling the corresponding parameter table to ensure that the connection between identification control, support control, and cutoff control remains consistent.

[0082] In this embodiment, the update cycle, observation cycle, and phase update cycle can also be managed separately by the control module. The update cycle mainly serves the update of the support voltage, the observation cycle mainly serves the insertion of the support removal observation window, and the phase update cycle mainly serves the redistribution of the phase offset. These three can be set to the same or different. As long as the control module ensures a clear sequence in its time management—that is, sampling is completed first, followed by judgment, and then switching and updating—the entire control process can be guaranteed to execute stably.

[0083] It should also be noted that the path equivalent impedance determination process and the support removal observation window control process in this embodiment do not conflict. Path equivalent impedance determination is mainly used before the channel branch enters the supported state to identify the source of low voltage. Support removal observation window is mainly used after the channel branch enters the supported state to determine whether the support level needs to be reduced and whether the discharge cutoff condition has been reached. Both revolve around the low-voltage discharge stage of the battery under test, but they correspond to different control stages. It is precisely because of the prior path equivalent impedance identification that the system can more accurately decide whether to allow the channel branch to enter the supported state; and it is precisely because of the subsequent addition of the support removal observation window that the system can continue to monitor the state of the battery under test after entering the supported state, rather than relying entirely on the apparent port voltage in the supported state.

[0084] This embodiment may further include a state storage function. The control module establishes a channel state record for each channel branch. The channel state record includes at least whether the current channel branch is in a supported state, the current supported level, the most recent path equivalent impedance, the most recent intrinsic cell voltage, the most recent natural terminal voltage, the most recent recovered terminal voltage, the current phase offset, and the current valley sampling window position. By saving these state values, the control module can continuously execute control between cycles, instead of starting from the beginning each time. This state storage function still serves the aforementioned control steps and does not constitute new technology content independent of the overall control chain.

[0085] In summary, the parallel low-voltage discharge power supply system provided in this embodiment, centered on the control module, organizes the battery interface, main discharge module, voltage support module, switching module, pulse width modulation drive module, voltage acquisition module, and current acquisition module into multiple parallel channel branches. By initiating an identification cycle at the first trigger threshold, the equivalent impedance of the path is determined using two sets of voltage and current data from the first and second sampling periods, further obtaining the path voltage drop and intrinsic cell voltage. By comparing the intrinsic cell voltage with the support initiation threshold, it is determined whether the switching module should connect the voltage support module in series between the battery under test and the main discharge module. The support voltage is determined based on the difference between the target port voltage and the intrinsic cell voltage and is continuously updated within the update cycle. During the support state, a de-support observation window is set to acquire the natural terminal voltage and the recovery terminal voltage to control the support level and discharge cutoff. Furthermore, by allocating phase offsets and setting valley sampling windows when multiple channel branches are simultaneously in the support state, a stable basis for sampling control in the support state is provided. Thus, all the structures, control actions, and their sequential logic in the aforementioned technical solution have been fully elaborated and specifically described in this embodiment.

[0086] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A parallel low-voltage discharge power supply system for battery formation and capacity control, characterized in that, It includes a control module and multiple parallel channel branches. Each channel branch is used to connect a battery under test. Each channel branch includes a main discharge module, a voltage support module, a switching module, a pulse width modulation drive module, a voltage acquisition module, and a current acquisition module. The current acquisition module is used to acquire the working discharge current in the discharge path where the main discharge module is located. The pulse width modulation drive module is connected to the voltage support module to drive the voltage support module; The control module is used to control the main discharge module to output a first set discharge current during the first sampling period and a second set discharge current during the second sampling period when the port voltage collected by the voltage acquisition module reaches the first trigger threshold. The control module is also used to determine the path equivalent impedance of the channel branch based on the first port voltage corresponding to the first sampling period, the second port voltage corresponding to the second sampling period, the first set discharge current, and the second set discharge current. The control module is also used to determine the path voltage drop value based on the path equivalent impedance and the working discharge current, determine the intrinsic cell voltage based on the port voltage and the path voltage drop value, and when the intrinsic cell voltage is not higher than the support start-up threshold, control the switching module to connect the voltage support module in series between the battery under test and the main discharge module, so that the channel branch enters the support state, and control the voltage support module to output the support voltage.

2. The parallel low-voltage discharge power supply system according to claim 1, characterized in that, Each of the channel branches also includes a battery interface, and the switching module is disposed between the battery interface and the main discharge module; The switching module is used to bypass the voltage support module in the first state and connect the voltage support module in series between the battery interface and the main discharge module in the second state.

3. The parallel low-voltage discharge power supply system according to claim 1, characterized in that, The first sampling period and the second sampling period are located within the same identification cycle, and the first set discharge current is greater than the second set discharge current; The control module is used to divide the difference between the first port voltage and the second port voltage by the difference between the first set discharge current and the second set discharge current to determine the path equivalent impedance.

4. The parallel low-voltage discharge power supply system according to claim 1, characterized in that, The control module is used to determine the path voltage drop value by multiplying the path equivalent impedance and the working discharge current, and to determine the intrinsic cell voltage by the difference between the port voltage and the path voltage drop value.

5. The parallel low-voltage discharge power supply system according to claim 1, characterized in that, The control module is used to determine the support voltage based on the difference between the target port voltage and the intrinsic cell voltage, and during the period when the channel branch is in the support state, to re-determine the intrinsic cell voltage according to the update cycle, and to update the support voltage based on the re-determined intrinsic cell voltage.

6. The parallel low-voltage discharge power supply system according to claim 1, characterized in that, The control module is used to control the voltage support module to enter the unsupported observation window according to the observation cycle during the period when the channel branch is in the supported state, and to collect the natural end voltage in the unsupported observation window, and to collect the recovery end voltage after the unsupported observation window ends.

7. The parallel low-voltage discharge power supply system according to claim 6, characterized in that, The control module is used to control the support level and discharge cutoff of the channel branch according to the natural terminal voltage and the recovery terminal voltage; The control module is also used to switch the current support level to a lower support level when the natural terminal voltage is higher than the support holding threshold, and to control the main discharge module to stop discharging when the natural terminal voltage is not higher than the cutoff judgment threshold and the difference between the recovery terminal voltage and the natural terminal voltage is not lower than the rebound judgment threshold.

8. The parallel low-voltage discharge power supply system according to claim 1, characterized in that, The control module is used to allocate different phase offsets to each channel branch in the support state according to the number of channel branches in the support state when multiple channel branches are in the support state at the same time, and to control each pulse width modulation drive module to drive the corresponding voltage support module according to the corresponding phase offset.

9. The parallel low-voltage discharge power supply system according to claim 8, characterized in that, The control module is used to distribute multiple phase offsets at equal intervals to multiple channel branches in the support state within one carrier cycle, and to reallocate the phase offsets in the next phase update cycle when the number of channel branches in the support state changes.

10. The parallel low-voltage discharge power supply system according to claim 8, characterized in that, The control module is used to set valley sampling windows for each channel branch in the support state, and output sampling trigger signals to each voltage acquisition module so that each voltage acquisition module can acquire port voltage within the valley sampling window of the corresponding channel branch. The control module is also used to perform support voltage control and discharge cutoff control on the corresponding channel branch based on the port voltage collected in the valley sampling window.

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