Voltage pre-charging control system and method and battery formation and capacity grading equipment

Abstract

The embodiment of the invention provides a voltage pre-charging control system and method and battery formation and capacity grading equipment. The voltage pre-charging control system comprises a double-phase buck-boost converter module, a protection module, a control module and a battery pack module, wherein the double-phase buck-boost converter module is composed of a first buck-boost converter and a second buck-boost converter which are the same in structure; wherein the positive-phase output end of the first buck-boost converter is connected with the positive electrode of the battery pack module through the protection module, the positive-phase output end of the second buck-boost converter is connected with the negative electrode of the battery pack module, and the negative-phase output end of the second buck-boost converter is grounded; the input ends of the two buck-boost converters are connected in parallel and are connected with a direct-current bus; the protection module is positioned on one side of the battery pack module, is connected with the first buck-boost converter and the battery pack module, and comprises a first protection tube and a second protection tube of which active electrodes and grid electrodes are correspondingly connected, a drain electrode of the first protection tube is connected with a capacitor of the first buck-boost converter, and a drain electrode of the second protection tube is connected with a positive electrode of the battery pack module; the control module is connected with other modules.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of energy storage devices, and particularly to a voltage pre-charge control system, a method, and a battery formation and grading device. Background Art

[0002] With the progress of society and the development of technology, the R & D and update frequency of products such as new energy vehicles has accelerated, making the application of batteries in life more and more important, especially lithium batteries. Among them, in the production process of batteries, a battery formation and grading device can provide charge and discharge services for a battery pack to be processed. Among them, during the formation and grading process, the battery pack to be processed has a need to discharge to zero voltage; or, before formation, since the voltage of the battery pack to be processed is negative, it cannot reach zero voltage during discharge. Therefore, a bi-directional buck-boost converter (Bi Buck-Boost converter) can be used in the battery formation and grading device. The Bi Buck-Boost converter has four working quadrants and can perform operations such as positive voltage charging, positive voltage discharging, negative voltage charging, and negative voltage discharging of the battery.

[0003] However, currently, when performing formation and grading on a battery, the Bi Buck-Boost converter in the battery formation and grading device still faces the problem of overshoot of the starting current and instantaneous surge current generated on the capacitor. Therefore, it is necessary to pre-charge the capacitor of the Bi Buck-Boost converter.

[0004] In this context, providing a voltage pre-charge control system to effectively suppress the surge current in the bi-directional buck-boost converter and improve the formation efficiency of the battery has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the embodiments of the present application provide a voltage pre-charge control system, a method, and a battery formation and grading device to pre-charge the capacitor voltage of the bi-directional buck-boost converter, thereby effectively suppressing the surge current in the bi-directional buck-boost converter and improving the formation efficiency of the battery.

[0006] To solve the above problems, the embodiments of the present application provide a voltage pre-charge control system, including a bi-directional buck-boost converter module, a protection module, a control module, and a battery pack module;

[0007] The battery pack module includes one or more batteries to be formed;

[0008] The dual-phase buck-boost converter module is composed of a first buck-boost converter and a second buck-boost converter with the same structure; the positive output terminal of the first buck-boost converter is connected to the positive electrode of the battery pack module through a protection module, and the negative output terminal is grounded; the positive output terminal of the second buck-boost converter is connected to the negative electrode of the battery pack module, and the negative output terminal is grounded; moreover, the input terminals of the first buck-boost converter and the second buck-boost converter are connected in parallel to the DC bus; wherein, the buck-boost converter includes two switching tubes that work complementarily, an inductor and a capacitor.

[0009] The protection module is located on one side of the battery pack module and is connected to the first buck-boost converter and the battery pack module; wherein, the protection module includes a first protection tube and a second protection tube, the source and gate of the first protection tube are respectively connected to the source and gate of the second protection tube correspondingly, and the drain of the first protection tube is connected to the capacitor of the first buck-boost converter, and the drain of the second protection tube is connected to the positive electrode of the battery pack module to protect the dual-phase buck-boost converter module when pre-charging the capacitor of the buck-boost converter by increasing the drive control signal in a fixed step.

[0010] The control module is connected to the dual-phase buck-boost converter module, the protection module and the battery pack module, and is used for controlling the operation of the dual-phase buck-boost converter module by controlling the switching tubes in the protection module and the buck-boost converter.

[0011] Optionally, the first buck-boost converter specifically includes a first switching tube, a second switching tube, a first inductor and a first capacitor; the second buck-boost converter specifically includes a third switching tube, a fourth switching tube, a second inductor and a second capacitor.

[0012] When pre-charging the first capacitor of the first buck-boost converter,

[0013] The first switching tube and the fourth switching tube are turned on, and the second switching tube and the third switching tube are turned off. The current flows through the first switching tube, the first inductor and the first capacitor in sequence in the dual-phase buck-boost converter, so as to charge the first capacitor; or,

[0014] The first switching tube, the second switching tube, the third switching tube and the fourth switching tube are all turned off, and the first inductor continues to flow current based on the second switching tube, so as to charge the first capacitor.

[0015] When pre-charging the second capacitor of the second buck-boost converter,

[0016] The second switching transistor and the third switching transistor are turned on, and the first switching transistor and the fourth switching transistor are turned off. The current flows through the third switching transistor, the second inductor, and the second capacitor in sequence in the bi-directional buck-boost converter, so as to charge the second capacitor. At the same time, the first capacitor and the first inductor form a current loop based on the second switching transistor, and the current flows through the first capacitor, the first inductor, and the second switching transistor in sequence; or,

[0017] The first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor are all turned off, and the second inductor continues to conduct current based on the fourth switching transistor, so as to charge the second capacitor.

[0018] Optionally, the control module includes: a main control module, a switch driving module, and a sampling module;

[0019] The main control module is connected to the switch driving module and the sampling module, and is configured to output control signals to the switch driving module and the sampling module to control the operation of the bi-directional buck-boost converter module;

[0020] The output end of the switch driving module is connected to the gate of the switching transistor of the buck-boost converter and the protection module, and is configured to control the working states of the switching transistor and the protection module;

[0021] The sampling module is connected to the battery pack module and the capacitor in the buck-boost converter, and is configured to sample the electrical parameters of the battery pack module and the pre-charge voltage of the capacitor.

[0022] Optionally, the main control module is an STM32G4 series chip; the sampling module is an AD7606 chip.

[0023] Optionally, the number of bi-directional buck-boost converter modules is one group or multiple groups;

[0024] If the number of bi-directional buck-boost converter modules is multiple groups, each bi-directional buck-boost converter module is correspondingly connected with a protection module, and the multiple groups of bi-directional buck-boost converter modules are connected in parallel based on the bi-directional buck-boost converter module connected to the battery pack module.

[0025] The embodiment of the present application further provides a voltage pre-charge control method, which is applied to the voltage pre-control system described above. The method includes:

[0026] Obtain the initial open-circuit voltage of the battery pack module;

[0027] According to the initial open-circuit voltage, use formula (1) to calculate the first estimated target pre-charge voltage corresponding to the capacitor in the first buck-boost converter:

[0028]

[0029] Calculate the second estimated target pre-charge voltage corresponding to the capacitor in the second buck-boost converter using Equation (2):

[0030]

[0031] And, calculate the first actual target pre-charge voltage corresponding to the capacitor in the first buck-boost converter using Equation (3):

[0032]

[0033] Calculate the second actual target pre-charge voltage corresponding to the capacitor in the second buck-boost converter using Equation (4):

[0034]

[0035] Where, V 1 represents the first estimated target pre-charge voltage; V 2 represents the second estimated target pre-charge voltage; V 1 ’ represents the first actual target pre-charge voltage; V 2 ’ represents the second actual target pre-charge voltage; Vo represents the initial open-circuit voltage of the battery pack module; D represents the duty cycle of the capacitor in the first buck-boost converter; V BUS represents the bus voltage; ΔV represents the deviation voltage of the capacitor in the first buck-boost converter, and its initial value is 0;

[0036] Pre-charge the capacitors in the first buck-boost converter and the second buck-boost converter to the actual target pre-charge voltages respectively;

[0037] Obtain the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter, and respectively determine whether the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter are within the error range of the estimated target pre-charge voltage. The error range of the estimated target pre-charge voltage is determined based on the conduction of the protection module and the difference between the target voltage of the battery pack module and the voltage difference of the capacitors in the first buck-boost converter and the second buck-boost converter when the inrush current of the device is less than 5 A;

[0038] If the judgment results are both negative, then return to execute the steps of pre-charging the capacitors in the first buck-boost converter and the second buck-boost converter respectively, obtaining the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter, and taking the difference between the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter obtained for the first time and the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter obtained again as the deviation voltage, and respectively calculate the actual target pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter;

[0039] If all the judgment results are yes, then taking the output current of the voltage pre-charge control system as zero as the target current, calculating the drive signal, adjusting the working states of the switching tubes in the bidirectional buck-boost converter module, and simultaneously turning on the protection module.

[0040] Optionally, the step of respectively pre-charging the capacitors in the first buck-boost converter and the second buck-boost converter includes:

[0041] Pre-charge the capacitor in the first buck-boost converter, and when the voltage on the capacitor in the first buck-boost converter is equal to the first actual target pre-charge voltage, the pre-charging ends;

[0042] Pre-charge the capacitor in the second buck-boost converter, and when the voltage on the capacitor in the second buck-boost converter is equal to the second actual target pre-charge voltage, the pre-charging ends.

[0043] Optionally, the first buck-boost converter specifically includes a first switching tube, a second switching tube, a first inductor, and a first capacitor; the second buck-boost converter specifically includes a third switching tube, a fourth switching tube, a second inductor, and a second capacitor.

[0044] Optionally, the pre-charging the capacitor in the first buck-boost converter is specifically:

[0045] The first switching tube and the fourth switching tube are turned on, the second switching tube and the third switching tube are turned off, and the current flows through the first switching tube, the first inductor, and the first capacitor in sequence in the bidirectional buck-boost converter, so as to charge the first capacitor; or,

[0046] The first switching tube, the second switching tube, the third switching tube, and the fourth switching tube are all turned off, and the first inductor continues to conduct current based on the second switching tube, so as to charge the first capacitor;

[0047] The pre-charging the capacitor in the second buck-boost converter is specifically:

[0048] The second switching tube and the third switching tube are turned on, the first switching tube and the fourth switching tube are turned off, and the current flows through the third switching tube, the second inductor, and the second capacitor in sequence in the bidirectional buck-boost converter, so as to charge the second capacitor; meanwhile, the first capacitor and the first inductor form a current loop based on the second switching tube, and the current flows through the first capacitor, the first inductor, and the second switching tube in sequence; or,

[0049] The first switching tube, the second switching tube, the third switching tube, and the fourth switching tube are all turned off, and the second inductor continues to conduct current based on the fourth switching tube, so as to charge the second capacitor.

[0050] The embodiment of the present application further provides a battery formation and grading equipment, including the voltage pre-charge control system as described above.

[0051] Compared with the prior art, the technical solution of the embodiment of the present application has the following advantages:

[0052] The voltage pre-charge control system provided by the embodiment of the present application is based on including a bi-directional buck-boost converter module, a protection module, a control module, and a battery pack module. The bi-directional buck-boost converter module is composed of a first buck-boost converter and a second buck-boost converter with the same structure. The positive output terminal of the first buck-boost converter is connected to the positive electrode of the battery pack module through the protection module, and the negative output terminal is grounded; the positive output terminal of the second buck-boost converter is connected to the negative electrode of the battery pack module, and the negative output terminal is grounded; moreover, the input terminals of the first buck-boost converter and the second buck-boost converter are connected in parallel to the DC bus; the protection module is connected to the first buck-boost converter and the battery pack module, located on one side of the battery pack module, and the control module is connected to the bi-directional buck-boost converter module, the protection module, and the battery pack module. When controlling the switching tubes in the protection module and the buck-boost converter to control the operation of the bi-directional buck-boost converter module, the number of control signals can be reduced, which is beneficial to the PCB layout and effectively saves the main control board resources of the voltage pre-charge control system provided in the formation and grading equipment.

[0053] Moreover, the protection module includes a first protection tube and a second protection tube. The source and gate of the first protection tube are respectively connected to the source and gate of the second protection tube correspondingly, and the drain of the first protection tube is connected to the capacitor of the first buck-boost converter, and the drain of the second protection tube is connected to the positive electrode of the battery pack module to protect the bi-directional buck-boost converter module when pre-charging the capacitor of the buck-boost converter by increasing the duty cycle in a fixed step, effectively reducing the surge current impact on the inductor, switching tube, and capacitor during pre-charging, thereby effectively suppressing the surge current in the bi-directional buck-boost converter and improving the formation efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0055] Figure 1 is a schematic structural diagram of the voltage pre-charge control system provided by the embodiment of the present application;

[0056] Figure 2 is a schematic diagram of the drive control signal provided by the embodiment of the present application;

[0057] Figure 3It is an alternative schematic diagram of the current flow direction provided by the embodiments of the present application;

[0058] Figure 4 It is another alternative schematic diagram of the current flow direction provided by the embodiments of the present application;

[0059] Figure 5 It is yet another alternative schematic diagram of the current flow direction provided by the embodiments of the present application;

[0060] Figure 6 It is still another alternative schematic diagram of the current flow direction provided by the embodiments of the present application;

[0061] Figure 7 It is another structural schematic diagram of the voltage pre-charge control system provided by the embodiments of the present application;

[0062] Figure 8 It is an alternative flowchart of the voltage pre-charge control method provided by the embodiments of the present application;

[0063] Figure 9 It is an alternative flowchart of step S300 provided by the embodiments of the present application;

[0064] Figure 10 It is a schematic diagram of the PI loop provided by the embodiments of the present application. Detailed implementation manners

[0065] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0066] As described in the background art, when the battery is subjected to formation and grading at present, the Bi Buck-Boost converter (biphase buck-boost converter) in the battery formation and grading equipment still faces the problem of overshoot of the starting current and instantaneous surge current generated on the capacitor. This is mainly because the traditional PWM pre-charging method is used to pre-charge the capacitor in the Bi Buck-Boost converter. There are 4 switching tubes in the Bi Buck-Boost converter, and 2 pairs of PWM signals are required. Moreover, two protection tubes are respectively arranged at the positive electrode of the battery pack and the negative electrode of the battery, and 2 control signals are required. Therefore, a total of 2 pairs of PWM signals and 2 control signals are used to perform control on the Bi Buck-Boost converter. At this time, the problem of overshoot of the starting current will be more obvious, resulting in surge current generated in the Bi Buck-Boost converter. In addition, generally, the series power conversion rate can reach dozens of kilowatts, and about 4 Bi Buck / Boost converters are often required to be connected in parallel. At this time, the entire system requires at least 8 pairs of PWM signals and 16 control signals, which further increases the problem of overshoot of the starting current, reduces the formation efficiency of the battery, and the pin resources of the main control chip cannot meet the connection requirements. Therefore, it is necessary to suppress the surge current in the biphase buck-boost converter to improve the formation efficiency of the battery.

[0067] In view of this, the embodiment of the present application provides an improved voltage pre-charging control scheme. The voltage pre-charging control system provided by the present application is based on including a biphase buck-boost converter module, a protection module, a control module, and a battery pack module. The biphase buck-boost converter module is composed of a first buck-boost converter and a second buck-boost converter with the same structure. The positive-phase output terminal of the first buck-boost converter is connected to the positive electrode of the battery pack module through the protection module, and the negative-phase output terminal is grounded; the positive-phase output terminal of the second buck-boost converter is connected to the negative electrode of the battery pack module, and the negative-phase output terminal is grounded; and the input terminals of the first buck-boost converter and the second buck-boost converter are connected in parallel to the DC bus; the protection module is connected to the first buck-boost converter and the battery pack module, and is located on one side of the battery pack module, and the control module is connected to the biphase buck-boost converter module, the protection module, and the battery pack module. When controlling the switching tubes in the protection module and the buck-boost converter to control the operation of the biphase buck-boost converter module, the number of control signals can be reduced, which is beneficial to the PCB layout and effectively saves the resources of the main control board of the formation and grading equipment provided with the voltage pre-charging control system.

[0068] Moreover, the protection module includes a first protection tube and a second protection tube. The source and gate of the first protection tube are respectively connected to the source and gate of the second protection tube correspondingly, and the drain of the first protection tube is connected to the capacitor of the first buck-boost converter. The drain of the second protection tube is connected to the positive pole of the battery pack module, so as to protect the dual-phase buck-boost converter module when pre-charging the capacitor of the buck-boost converter by increasing the duty cycle in a fixed step, effectively reducing the surge current impact on the inductor, switch tube and capacitor during pre-charging, thereby effectively suppressing the surge current in the dual-phase buck-boost converter and improving the formation efficiency of the battery.

[0069] Among them, Figure 1 An exemplary structural schematic diagram of the voltage pre-charging control system provided by an embodiment of the present application is shown. As Figure 1 shown, the voltage pre-charging control system may include a dual-phase buck-boost converter module, a protection module, a control module and a battery pack module.

[0070] Among them, the battery pack module includes one or more batteries to be formed ( Figure 1 shown as BAT1 to BATN in the figure). In a specific example where the battery pack module includes multiple batteries to be formed, the multiple batteries to be formed may be connected in series or in parallel.

[0071] The dual-phase buck-boost converter module is composed of a first buck-boost converter and a second buck-boost converter with the same structure. Among them, the positive-phase output terminal of the first buck-boost converter is connected to the positive pole of the battery pack module through the protection module, and the negative-phase output terminal is grounded (PGND). The positive-phase output terminal of the second buck-boost converter is connected to the negative pole of the battery pack module, and the negative-phase output terminal is grounded (PGND). And, the input terminals of the first buck-boost converter and the second buck-boost converter are connected in parallel to the DC bus (VBUS+). Among them, the buck-boost converter includes two switch tubes that work complementarily ( Figure 1 shown as Q1 and Q2, Q3 and Q4 in the figure to represent two switch tubes that work complementarily), an inductor ( Figure 1 shown as L1, L2 in the figure to represent the inductor) and a capacitor ( Figure 1 shown as C1, C2 in the figure to represent the capacitor). It should be noted that the switch tubes in the embodiments of the present application may be, for example, SiC MOS, SiMOS or IGBT switches, and internally parasitize diodes.

[0072] The protection module is connected to the first buck-boost converter and the battery pack module, and is located on one side of the battery pack module. Among them, the protection module includes a first protection tube ( Figure 1 shown as S1 in the figure) and a second protection tube ( Figure 1As shown in S2 in the figure, the source and gate of the first protection tube are respectively and correspondingly connected to the source and gate of the second protection tube, and the drain of the first protection tube is connected to the capacitor of the first buck-boost converter, and the drain of the second protection tube is connected to the positive pole of the battery pack module.

[0073] It should be noted that in this embodiment, the protection tubes S1 and S2 included in the protection module are in a back-to-back form. When the protection tubes are turned off, the current is cut off, thereby protecting the voltage pre-charge control system.

[0074] Based on the source of S1 and the source of S2, the gate of S1 is connected to the gate of S2, so that S1 and S2 can share a path of PWM signal, defined as PRT (protect, protection tube), to protect the dual-phase buck-boost converter module when pre-charging the capacitor of the buck-boost converter at a fixed step to increase the duty cycle, effectively reducing the surge current impact on the inductor, switch tube and capacitor during pre-charging, thereby effectively suppressing the surge current in the dual-phase buck-boost converter and improving the formation efficiency of the battery.

[0075] Moreover, the drain of S1 is connected to the capacitor C1, and the drain of S2 is connected to the positive pole of the battery pack module. Compared with the circuit connection method of connecting the drain of one protection tube to the positive pole of the battery pack module, the source to the capacitor C1, and the drain of the other protection tube to the negative pole of the battery pack module, the source to the capacitor C2, the embodiment of the present application can reduce the number of control signals, is beneficial to the PCB layout, and effectively saves the main control board resources of the formation and grading equipment provided with the voltage pre-charge control system.

[0076] The control module is connected to the dual-phase buck-boost converter module, the protection module and the battery pack module, and is used to control the operation of the dual-phase buck-boost converter module by controlling the switch tubes in the protection module and the buck-boost converter.

[0077] It should be noted that the control module can be a circuit module including chips such as a power control dedicated chip, a digital processing chip, a single-chip microcomputer, and an embedded chip. Based on connecting the dual-phase buck-boost converter module, the protection module and the battery pack module, it can send corresponding control signals to the corresponding modules, thereby realizing the control of the operation of the dual-phase buck-boost converter module. In an optional example, the control module can send a driving control signal that increases slowly. This driving control signal is, for example, a PWM signal, which can increase at a fixed step. This fixed step is relatively small. See Figure 2 the schematic diagram of the driving control signal shown. Ugs represents the voltage between the gate and source of the driving switch tube, that is, the signal for driving the switch tube. The initial duty cycle is 0, and it increases step by step at a step of 5%, and each step is executed for 10 cycles, so that the switch tube works at a constant cycle.

[0078] Therefore, based on the connection relationship between the control module, the protection module, and the switching transistors in the buck-boost converter, the dual-phase buck-boost converter module can pre-charge the capacitors it contains by slowly increasing the duty cycle and intermittent hiccupping, effectively reducing the surge current impact on the inductor, switching transistors, and capacitors during pre-charging, thereby effectively suppressing the surge current in the dual-phase buck-boost converter and improving the formation efficiency of the battery.

[0079] In some embodiments, as shown in Figure 1 Based on the buck-boost converter including two complementary switching transistors, an inductor, and a capacitor, the first buck-boost converter in the dual-phase buck-boost converter module may specifically include a first switching transistor Q1, a second switching transistor Q2, a first inductor L1, and a first capacitor C1. The second buck-boost converter may specifically include a third switching transistor Q3, a fourth switching transistor Q4, a second inductor L2, and a second capacitor C2.

[0080] It should be noted that in the embodiments of the present application, the first switching transistor Q1 and the fourth switching transistor Q4 share a common PWM signal, defined as PMMH. The second switching transistor Q2 and the third switching transistor Q3 share a common PWM signal, defined as PWML. PMWH and PWML are in a complementary relationship and cannot be high level at the same time.

[0081] When pre-charging the first capacitor C1 of the first buck-boost converter, as an alternative implementation, as shown in the optional schematic diagram of the current flow direction indicated by the thick line in Figure 3 , the first switching transistor Q1 and the fourth switching transistor Q4 are turned on, and the second switching transistor Q2 and the third switching transistor Q3 are turned off. The current flows through the first switching transistor Q1, the first inductor L1, and the first capacitor C1 in sequence in the dual-phase buck-boost converter, so as to charge the first capacitor C1. At this time, since the second capacitor C2 is not pre-charged, its voltage remains zero.

[0082] As another alternative implementation, as shown in another optional schematic diagram of the current flow direction indicated by the thick line in Figure 4 , the first switching transistor Q1, the second switching transistor Q2, the third switching transistor Q3, and the fourth switching transistor Q4 are all turned off. The first inductor L1 continues to flow current based on the second switching transistor Q2, so as to charge the first capacitor C1. At this time, it can be a continuous charge of the first capacitor C1.

[0083] Corresponding to Figure 2 the shown drive control signal, when pre-charging the first capacitor C1, the switching transistor Q1 operates at a constant period, and the switching transistor Q2 is always in the off state. The upper limit value of the duty cycle can be set as:

[0084]

[0085] where Vo is the initial open-circuit voltage of the battery pack module and also the target pre-charging voltage of the battery pack module; V BUSVbus represents the bus voltage; ΔV represents the deviation voltage of the capacitor in the first buck-boost converter, and its initial value is 0.

[0086] When pre-charging the second capacitor C2 of the second buck-boost converter, as an alternative implementation, as Figure 5 Another alternative schematic diagram of the current flow direction shown by the thick line in the figure, the second switching tube Q2 and the third switching tube Q3 are turned on, the first switching tube Q1 and the fourth switching tube Q4 are turned off, and the current flows through the third switching tube Q3, the second inductor L2 and the second capacitor C2 in sequence in the dual-phase buck-boost converter, so as to charge the second capacitor C2. At the same time, the first capacitor Q1 and the first inductor L1 form a current loop based on the second switching tube Q2, and the current flows through the first capacitor C1, the first inductor L1 and the second switching tube Q2 in sequence, so that the first capacitor C1 discharges.

[0087] As another alternative implementation, as Figure 6 Another alternative schematic diagram of the current flow direction shown by the thick line in the figure, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 are all turned off, and the second inductor L2 continues to flow based on the fourth switching tube Q4v, so as to charge the second capacitor C2. At this time, it can be a continuous charge of the second capacitor C2.

[0088] Corresponding to Figure 2 the driving control signal shown, when pre-charging the second capacitor C2, the switching tube Q3 works with a constant period, and the switching tube Q4 is always in the off state, and the upper limit value of the duty cycle can be set as:

[0089]

[0090] In some embodiments, referring to Figure 1 shown in the figure, the control module of the embodiment of the present application may include: a main control module, a switch driving module and a sampling module.

[0091] Among them, the main control module is connected to the switch driving module and the sampling module, and is used to output control signals to the switch driving module and the sampling module to control the operation of the dual-phase buck-boost converter module.

[0092] As an alternative implementation, the main control module may be a dedicated power control chip, a digital processing chip, a single-chip microcomputer, an embedded chip, etc. In a specific example, the main control module of the embodiment of the present application may be an STM32G4 series chip.

[0093] The output terminal of the switch driving module is connected to the switch tube of the buck-boost converter and the gate of the protection module, and is used to control the working states of the switch tube and the protection module. Specifically, the output of the switch driving module can be connected to the gates of the first switch tube Q1, the second switch Q2, the third switch tube Q3, the fourth switch tube Q4, the first protection tube S1 and the second protection tube S2. Based on the control of the main control module, the switch driving module can control the turning on and off of the switch tubes and the protection tubes.

[0094] The sampling module is connected to the battery pack module and the capacitor in the buck-boost converter, and is used to sample the electrical parameters of the battery pack module and the pre-charging voltage of the capacitor. As an optional implementation, the sampling module can be, for example, an analog-to-digital converter, which is used to collect signals such as the voltage of C1, the voltage of C2, the output voltage Vo, and the output current Io, and feedback the collected signals to the main control module. In a specific example, the sampling module in the embodiment of the present application can be an AD7606 chip.

[0095] It should be noted that the sampling module in the embodiment of the present application can have a protection function. When abnormal signals such as overvoltage, undervoltage of the voltage of the first capacitor C1, the voltage of the second capacitor C2, the output voltage Vo, and overcurrent, undercurrent of the output current Io are sampled, in an optional example, the driving signal of the switch tube can be pulled low and fed back to the main control module in time to turn off the corresponding switch to protect the normal operation of the circuit. In another optional example, the sampling module can monitor system anomalies through real-time sampling, so as to stop the PWM signal output and turn off the protection tube when an abnormal situation occurs.

[0096] In some embodiments, the number of buck-boost converter modules in the embodiment of the present application is one group or multiple groups. Among them, as Figure 7 shown in another structural schematic diagram of the voltage pre-charging control system in the embodiment of the present application, if the number of buck-boost converter modules is multiple groups, each buck-boost converter module is correspondingly connected with a protection module, and the multiple groups of buck-boost converter modules are connected in parallel based on the buck-boost converter module connected to the battery pack module.

[0097] It can be seen that the voltage pre-charge control system provided in the embodiment of the present application is based on a two-phase buck-boost converter module, a protection module, a control module and a battery pack module. The two-phase buck-boost converter module is composed of a first buck-boost converter and a second buck-boost converter with the same structure. The positive phase output end of the first buck-boost converter is connected to the positive pole of the battery pack module through the protection module, and the negative phase output end is grounded; the positive phase output end of the second buck-boost converter is connected to the negative pole of the battery pack module, and the negative phase output end is grounded; and the input ends of the first buck-boost converter and the second buck-boost converter are connected in parallel to the DC bus; the protection module is connected to the first buck-boost converter and the battery pack module, and is located on one side of the battery pack module, and the control module is connected to the two-phase buck-boost converter module, the protection module and the battery pack module, and is used to control the operation of the two-phase buck-boost converter module based on controlling the switch tube in the protection module and the buck-boost converter. In this case, the number of control signals can be reduced, which is beneficial to PCB layout and effectively saves the resources of the main control board provided with a voltage pre-charge control system in the capacity-splitting device.

[0098] Moreover, the protection module includes a first protection tube and a second protection tube, the source and gate of the first protection tube are respectively connected to the source and gate of the second protection tube, and the drain of the first protection tube is connected to the capacitor of the first buck-boost converter, and the drain of the second protection tube is connected to the positive electrode of the battery pack module, so as to protect the two-phase buck-boost converter module when the capacitor of the buck-boost converter is pre-charged by increasing the duty cycle at a fixed step size, effectively reduce the surge current impact on the inductor, switch tube and capacitor during pre-charging, thereby effectively suppressing the surge current in the two-phase buck-boost converter and improving the formation efficiency of the battery.

[0099] The present application also provides a voltage pre-charging control method, which can be applied to the voltage pre-charging control system described above. Figure 8 The following is an exemplary diagram of an optional flow chart of a voltage pre-charge control method according to an embodiment of the present application. Figure 8 As shown, the following steps are included:

[0100] Step S100: obtaining the initial open circuit voltage of the battery module.

[0101] Specifically, the main control module may control the sampling module to sample the initial open-circuit voltage of the battery pack module, and the voltage value is Vo.

[0102] Step S200: Calculate the first estimated target pre-charge voltage corresponding to the capacitor in the first buck-boost converter and the second estimated target pre-charge voltage corresponding to the capacitor in the second buck-boost converter according to the initial open-circuit voltage, and the first actual target pre-charge voltage corresponding to the capacitor in the first buck-boost converter and the second actual target pre-charge voltage corresponding to the capacitor in the second buck-boost converter.

[0103] Specifically, the first estimated target pre-charge voltage corresponding to the capacitor in the first buck-boost converter can be calculated using formula (1):

[0104]

[0105] where, V 1 represents the first estimated target pre-charge voltage; Vo represents the initial open-circuit voltage of the battery pack module; D represents the duty cycle of the capacitor in the first buck-boost converter; V BUS represents the bus voltage.

[0106] The second estimated target pre-charge voltage corresponding to the capacitor in the second buck-boost converter can be calculated using formula (2):

[0107]

[0108] where, V 2 represents the second estimated target pre-charge voltage; Vo represents the initial open-circuit voltage of the battery pack module; D represents the duty cycle of the capacitor in the first buck-boost converter; V BUS represents the bus voltage.

[0109] The first actual target pre-charge voltage corresponding to the capacitor in the first buck-boost converter can be calculated using formula (3):

[0110]

[0111] where, V 1 ’ represents the first actual target pre-charge voltage; Vo represents the initial open-circuit voltage; V BUS represents the bus voltage; ΔV represents the deviation voltage of the capacitor in the first buck-boost converter, and its initial value is 0.

[0112] The second actual target pre-charge voltage corresponding to the capacitor in the second buck-boost converter can be calculated using formula (4):

[0113]

[0114] where, V 2 ’ represents the second actual target pre-charge voltage; Vo represents the initial open-circuit voltage; V BUS represents the bus voltage.

[0115] It should be noted that V 1 represents the first estimated target pre-charge voltage, V 2 represents the second estimated target pre-charge voltage, D represents the duty cycle of Q1. Since Q2 is complementary to Q1 and the source electrodes of Q2 and Q3 are connected, the duty cycle of Q3 is 1 - D. The relationship between the battery voltage Vo and the bus voltage V BUS is as follows:

[0116] Vo = V 1 - V 2 = V BUS ·D - V BUS ·(1 - D) = V BUS ·(2D - 1). Based on this, furthermore, the formula (1) for calculating the first estimated target pre-charge voltage V1 and the formula (2) for calculating the second estimated target pre-charge voltage V2 can be obtained.

[0117] It should be further noted that when C2 is pre-charged, Q2 is turned on. Since the gates of Q3 and Q2 are connected in parallel and share the same PWM signal, C1 will discharge. If the pre-charge voltage is set to the estimated target pre-charge voltage, when the actual pre-charge ends, the actual target pre-charge voltage V1' of C1 will be too small, while the actual target pre-charge voltage V2' of C2 remains unchanged. Therefore, the voltage deviation value ΔV should be added to the actual target pre-charge voltage V1' of C1.

[0118] After obtaining the actual target pre-charge voltage, step S300 can be further executed.

[0119] Step S300: Pre-charge the capacitors in the first buck-boost converter and the second buck-boost converter to the actual target pre-charge voltage respectively.

[0120] In some embodiments, Figure 9 an optional flow schematic diagram of step S300 is exemplarily shown. As Figure 9 shown, step S300 may include:

[0121] Step S301: Pre-charge the capacitor in the first buck-boost converter. When the voltage on the capacitor in the first buck-boost converter is equal to the first actual target pre-charge voltage, the pre-charge ends.

[0122] Step S302: Pre-charge the capacitor in the second buck-boost converter. When the voltage on the capacitor in the second buck-boost converter is equal to the second actual target pre-charge voltage, the pre-charge ends.

[0123] Optionally, the first buck-boost converter specifically includes a first switching tube, a second switching tube, a first inductor, and a first capacitor; the second buck-boost converter specifically includes a third switching tube, a fourth switching tube, a second inductor, and a second capacitor.

[0124] As an alternative implementation, the pre-charging of the capacitors in the first buck-boost converter may specifically be:

[0125] The first switch tube and the fourth switch tube are turned on, and the second switch tube and the third switch tube are turned off. The current flows through the first switch tube, the first inductor, and the first capacitor in sequence in the dual-phase buck-boost converter, so as to charge the first capacitor; or, the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are all turned off, and the first inductor continues to flow current based on the second switch tube, so as to charge the first capacitor.

[0126] As an alternative implementation, the pre-charging of the capacitors in the second buck-boost converter may specifically be:

[0127] The second switch tube and the third switch tube are turned on, and the first switch tube and the fourth switch tube are turned off. The current flows through the third switch tube, the second inductor, and the second capacitor in sequence in the dual-phase buck-boost converter, so as to charge the second capacitor; meanwhile, the first capacitor and the first inductor form a current loop based on the second switch tube, and the current flows through the first capacitor, the first inductor, and the second switch tube in sequence; or, the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube are all turned off, and the second inductor continues to flow current based on the fourth switch tube, so as to charge the second capacitor.

[0128] Step S400: Obtain the pre-charging voltages of the capacitors in the first buck-boost converter and the second buck-boost converter, and respectively determine whether the pre-charging voltages of the capacitors in the first buck-boost converter and the second buck-boost converter are within the error range of the estimated target pre-charging voltage.

[0129] Wherein, the error range of the estimated target pre-charging voltage is the difference between the voltage of the battery pack module and the voltage difference of the capacitors in the first buck-boost converter and the second buck-boost converter when the protection module is turned on and the inrush current of the device is less than 5 A.

[0130] It should be noted that the inventor found through actual debugging that: when the error range is taken as 5% of the bus voltage V BUS , the protection tube can be turned on without generating a large inrush current, and the inrush current is less than 5 A. At the same time, the deviation value needs to be adjusted. If the value of V1’ is smaller than the calculated actual target pre-charging voltage, the deviation voltage value needs to be increased.

[0131] It should be further noted that, in order to protect the circuit system from being damaged, in the pre-charging in the embodiments of the present application, the actual pre-charging voltage Vo’ of the battery pack module also needs to be ensured to be within the error range, where Vo’ represents the voltage difference of the capacitors in the first buck-boost converter and the second buck-boost converter.

[0132] The error range can be determined according to the magnitude of the inrush current when the protection module is turned on. If the actual pre-charge voltage Vo' of the battery pack module is within the error range of the initial open-circuit voltage Vo, step S400 can be executed. If the actual pre-charge voltage Vo' of the battery pack module is not within the error range, it will re-enter the pre-charge step. For example, the initial open-circuit voltage of the battery pack module is 10V, and the target pre-charge voltage is also 10V. Through calculation, the first capacitor should be pre-charged to 30V, and the second capacitor should be pre-charged to 20V. If the first actual target pre-charge voltage of the first capacitor is 29V and the second actual target pre-charge voltage of the second capacitor is 20V after pre-charging, the difference between the two is 9V, and this 9V voltage is the actual pre-charge voltage corresponding to the battery pack module. However, for the battery pack module with a target pre-charge voltage of 10V, if the first capacitor and the second capacitor are connected to the battery pack module, based on a voltage difference of 1V, an inrush current will be generated in the circuit. When this 1V voltage difference is within the acceptable error range, step S400 can be executed. When this 1V voltage difference is not within the acceptable error range, the first capacitor and the second capacitor will be re-pre-charged. If the error range of the pre-charge voltage Vo' of the battery pack module is ±1V, the voltage pre-charge range of the first capacitor can be obtained as 29 - 31V, and the voltage pre-charge range of the second capacitor is 19V - 21V.

[0133] As an alternative implementation, if the judgment results are all negative, it will return to execute the steps of pre-charging the capacitors in the first buck-boost converter and the second buck-boost converter respectively, obtaining the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter, and taking the difference between the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter obtained for the first time and the pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter obtained again as the deviation voltage, and calculating the actual target pre-charge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter respectively. That is, define the actual pre-charge voltage value of C1 after pre-charging as Vf, the difference between the estimated target pre-charge voltage V1 of C1 and the actual target pre-charge voltage as V1 - Vf, assign V1 - Vf to ΔV, and re-enter the pre-charge step.

[0134] As another alternative implementation, if the judgment results are all positive, take the output current of the voltage pre-charge control system being zero as the target current, calculate the drive signal, adjust the working states of the switching tubes in the dual-phase buck-boost converter module, and turn on the protection module simultaneously.

[0135] It should be noted that the PI closed-loop calculation is started with zero current as the target current of the output current. Figure 10 Exemplarily shows a schematic diagram of the PI loop. As Figure 10As shown, the main control module samples the current Io of the battery pack module through the sampling module and compares it with zero current to generate a current error signal Ierr. The current error signal is input to the PI controller to calculate the duty cycle, which is then input to the PWM generator to generate a pair of complementary PWM signals to regulate the switching and conduction of the switching tubes Q1, Q2, Q3, and Q4. Furthermore, the voltage pre-charge control system is switched to the normal operating mode. At the same time, the main control module can also send a PRT signal through the switch driving unit to turn on the protection tubes S1 and S2 until the system is stable.

[0136] The embodiment of the present application also provides a batteryized component capacitance device, and the batteryized component capacitance device may include the voltage pre-charge control system as described above.

[0137] The above describes multiple embodiment solutions provided by the embodiments of the present application. The various alternative ways introduced in each embodiment solution can be combined and cross-referenced with each other without conflict, thereby extending a variety of possible embodiment solutions, all of which can be considered as the embodiment solutions disclosed and made public by the embodiments of the present application.

[0138] Although the embodiments of the present application are disclosed as above, the present application is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A voltage pre-charge control system, characterized in that: It includes a two-phase buck-boost converter module, a protection module, a control module and a battery pack module; The battery module includes one or more batteries to be formed; The dual-phase buck-boost converter module is composed of a first buck-boost converter and a second buck-boost converter of the same structure; the positive phase output end of the first buck-boost converter is connected to the positive electrode of the battery module through the protection module, and the negative phase output end is grounded; the positive phase output end of the second buck-boost converter is connected to the negative electrode of the battery module, and the negative phase output end is grounded; and the input ends of the first buck-boost converter and the second buck-boost converter are connected in parallel to the DC bus; wherein the buck-boost converter includes two switch tubes, an inductor and a capacitor working in a complementary manner; The protection module is located at one side of the battery pack module and is connected to the first buck-boost converter and the battery pack module; wherein the protection module includes a first protection tube and a second protection tube, the source and gate of the first protection tube are respectively connected to the source and gate of the second protection tube, and the drain of the first protection tube is connected to the capacitor of the first buck-boost converter, and the drain of the second protection tube is connected to the positive electrode of the battery pack module, so as to protect the two-phase buck-boost converter module when the driving control signal is increased at a fixed step size to pre-charge the capacitor of the buck-boost converter; The control module is connected to the two-phase buck-boost converter module, the protection module and the battery pack module, and is used to control the operation of the two-phase buck-boost converter module based on controlling the protection module and the switch tube in the buck-boost converter.

2. The voltage precharge control system according to claim 1, characterized in that: The first buck-boost converter specifically includes a first switch tube, a second switch tube, a first inductor and a first capacitor; the second buck-boost converter specifically includes a third switch tube, a fourth switch tube, a second inductor and a second capacitor; When the first capacitor of the first buck-boost converter is pre-charged, The first switch tube and the fourth switch tube are turned on, the second switch tube and the third switch tube are turned off, and the current flows through the first switch tube, the first inductor and the first capacitor in the two-phase buck-boost converter in sequence, so that the first capacitor is charged; or, The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all turned off, and the first inductor is freewheeling based on the second switch tube, so as to charge the first capacitor; When the second capacitor of the second buck-boost converter is pre-charged, The second switch tube and the third switch tube are turned on, the first switch tube and the fourth switch tube are turned off, and the current flows through the third switch tube, the second inductor and the second capacitor in the two-phase buck-boost converter in sequence, so that the second capacitor is charged; at the same time, the first capacitor and the first inductor form a current loop based on the second switch tube, and the current flows through the first capacitor, the first inductor and the second switch tube in sequence; or, The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all turned off, and the second inductor is freewheeling based on the fourth switch tube, so that the second capacitor is charged.

3. The voltage precharge control system according to claim 1, characterized in that: The control module includes: a main control module, a switch driving module and a sampling module; The main control module is connected to the switch driving module and the sampling module, and is used to output a control signal to the switch driving module and the sampling module to control the operation of the two-phase buck-boost converter module; The output end of the switch driving module is connected to the switch tube of the buck-boost converter and the gate of the protection module, and is used to control the working state of the switch tube and the protection module; The sampling module is connected to the battery pack module and the capacitor in the buck-boost converter, and is used to sample the electrical parameters of the battery pack module and the pre-charge voltage of the capacitor.

4. The voltage precharge control system according to claim 3, characterized in that: The main control module is an STM32G4 series chip; the sampling module is an AD7606 chip.

5. The voltage precharge control system according to claim 1, characterized in that: The number of the two-phase buck-boost converter modules is one or more groups; If there are multiple groups of two-phase buck-boost converter modules, each two-phase buck-boost converter module is connected to a corresponding protection module, and multiple groups of two-phase buck-boost converter modules are connected in parallel based on the two-phase buck-boost converter modules connected to the battery pack module.

6. A voltage pre-charge control method, characterized in that: Applied to the voltage precontrol control system according to any one of claims 1 to 5, the method comprises: Obtaining the initial open circuit voltage of the battery pack module; According to the initial open circuit voltage, the first estimated target pre-charge voltage corresponding to the capacitor in the first buck-boost converter is calculated using formula (1): The second estimated target pre-charge voltage corresponding to the capacitor in the second buck-boost converter is calculated using formula (2): And, using formula (3) to calculate the first actual target pre-charge voltage corresponding to the capacitor in the first buck-boost converter: The second actual target pre-charge voltage corresponding to the capacitor in the second buck-boost converter is calculated using formula (4): Wherein, V1 represents the first estimated target pre-charge voltage; V2 represents the second estimated target pre-charge voltage; V1' represents the first actual target pre-charge voltage; V2' represents the second actual target pre-charge voltage; Vo represents the initial open circuit voltage of the battery pack module; D represents the duty cycle of the capacitor in the first buck-boost converter; V BUS represents the bus voltage; ΔV represents the deviation voltage of the capacitor in the first buck-boost converter, and its initial value is 0; Pre-charging the capacitors in the first buck-boost converter and the second buck-boost converter to actual target pre-charging voltages respectively; Obtaining the pre-charge voltage of the capacitor in the first buck-boost converter and the second buck-boost converter, and respectively determining whether the pre-charge voltage of the capacitor in the first buck-boost converter and the second buck-boost converter is within an error range of an estimated target pre-charge voltage, wherein the error range of the estimated target pre-charge voltage is determined based on the difference between the target voltage of the battery pack module and the voltage difference of the capacitor in the first buck-boost converter and the second buck-boost converter when the protection module is turned on and the surge current of the device is less than 5 amperes; If the judgment results are all negative, the method returns to the step of precharging the capacitors in the first buck-boost converter and the second buck-boost converter respectively, obtaining the precharge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter, and taking the difference between the precharge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter obtained for the first time and the precharge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter obtained again, and using the difference as the deviation voltage to calculate the actual target precharge voltages of the capacitors in the first buck-boost converter and the second buck-boost converter respectively; If the judgment results are all yes, the output current of the voltage pre-charge control system is zero as the target current, the drive signal is calculated, the working state of the switch tube in the two-phase buck-boost converter module is adjusted, and the protection module is turned on at the same time.

7. The voltage precharge control method according to claim 6, characterized in that: The steps of precharging the capacitors in the first buck-boost converter and the second buck-boost converter respectively include: Pre-charging the capacitor in the first buck-boost converter, and when the voltage on the capacitor in the first buck-boost converter is equal to the first actual target pre-charging voltage, the pre-charging ends; The capacitor in the second buck-boost converter is pre-charged, and the pre-charging ends when the voltage on the capacitor in the second buck-boost converter is equal to the second actual target pre-charging voltage.

8. The voltage precharge control method according to claim 7, characterized in that: The first buck-boost converter specifically includes a first switch tube, a second switch tube, a first inductor and a first capacitor; the second buck-boost converter specifically includes a third switch tube, a fourth switch tube, a second inductor and a second capacitor.

9. The voltage precharge control method according to claim 8, characterized in that: The pre-charging of the capacitor in the first buck-boost converter is specifically: The first switch tube and the fourth switch tube are turned on, the second switch tube and the third switch tube are turned off, and the current flows through the first switch tube, the first inductor and the first capacitor in the two-phase buck-boost converter in sequence, so that the first capacitor is charged; or, The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all turned off, and the first inductor is freewheeling based on the second switch tube, so as to charge the first capacitor; The pre-charging of the capacitor in the second buck-boost converter is specifically: The second switch tube and the third switch tube are turned on, the first switch tube and the fourth switch tube are turned off, and the current flows through the third switch tube, the second inductor and the second capacitor in the two-phase buck-boost converter in sequence, so that the second capacitor is charged; at the same time, the first capacitor and the first inductor form a current loop based on the second switch tube, and the current flows through the first capacitor, the first inductor and the second switch tube in sequence; or, The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all turned off, and the second inductor is freewheeling based on the fourth switch tube, so that the second capacitor is charged.

10. A battery capacity conversion device, characterized in that: It comprises a voltage pre-charging control system as described in any one of claims 1 to 5.

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