On-line capacity checking and charge-discharge control system for wide-voltage storage battery pack

Abstract

The invention discloses a wide-voltage storage battery pack on-line capacity checking and charge-discharge control system, and the system comprises a monomer detection module which is connected with a central controller and is used for monitoring the voltage, temperature and internal resistance data of storage battery monomers and obtaining the number of the storage battery monomers in a storage battery pack; the switching control device is simultaneously connected with the plurality of storage battery packs and the central controller and is used for controlling the switching of the plurality of storage battery packs; the voltage boosting and reducing device is connected with the switching control device and the central controller at the same time and used for controlling voltage boosting and reducing of the storage battery packs; and the central controller is used for controlling the switching control device and the buck-boost device by sending a signal so as to realize on-line capacity checking and charge-discharge management of the plurality of storage battery packs. Through multi-dimensional innovation, the capacity checking efficiency and the system reliability are remarkably improved, and the method has important engineering application value.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics and energy storage systems, and in particular to an on-line capacity verification, charging and discharging control system for a wide-voltage battery pack. Background Art

[0002] Due to its high reliability and stability, DC systems are widely used in many key fields, such as power plants and substations: powering control, protection, signal and communication equipment; data centers: providing stable power for servers and network equipment; communication systems: powering base stations and transmission equipment; industrial control: powering control systems such as PLCs and DCSs.

[0003] With the development of various AI technologies, higher requirements are also put forward for DC systems. However, the batteries of DC systems have always been the main reason affecting the safety of DC systems. Due to its own technical reasons, the life and failure of lead-acid batteries are normal events. Lithium batteries have obvious advantages in terms of life. However, the safety of lithium batteries may lead to greater risks. Therefore, in many backup batteries of DC systems, lead-acid batteries with the highest safety are still used.

[0004] There are many occasions where DC systems are applied, and the capacity verification of lead-acid batteries has become a key technical point for battery maintenance. From the normal -48V communication DC system, 110V and 220V operating power systems, to 380V and 480V UPS DC systems, there are problems with battery capacity verification and discharge. In the prior art, the battery capacity verification has a low capacity verification efficiency, and the capacity verification needs to be carried out offline, disconnecting the load or shutting down the system, resulting in power supply interruption and affecting production continuity. Summary of the Invention

[0005] The object of the present invention is to overcome the disadvantages that the battery capacity verification in the prior art has a low capacity verification efficiency, the capacity verification needs to be carried out offline, disconnecting the load or shutting down the system, resulting in power supply interruption and affecting production continuity, and to provide an on-line capacity verification, charging and discharging control system for a wide-voltage battery pack.

[0006] The object of the present invention is achieved by the following technical solutions: An on-line capacity verification, charging and discharging control system for a wide-voltage battery pack, comprising: A single-cell detection module, connected to a central controller, for monitoring the voltage, temperature, internal resistance data of battery cells and obtaining the number of battery cells in the battery pack; The switching control device is connected to several battery packs and the central controller simultaneously, and is used to control the switching of several battery packs; the buck-boost device is connected to the switching control device and the central controller simultaneously, and is used to control the voltage rise and fall of several battery packs; the central controller is used to control the switching control device and the buck-boost device by sending signals to achieve online capacity verification and charge and discharge management of several battery packs.

[0007] Preferably, the online capacity verification performs capacity measurement of the battery pack according to the following formula: In the formula, f x1 is a binary function of the total voltage of the battery pack. If the total voltage of the battery pack exceeds the set voltage, then f x1 is 0, otherwise f x1 is 1; f x2 is a binary function of the temperature of the battery cells in the battery pack. If any of the battery cell temperatures exceeds the set temperature, f x2 is 0, otherwise f x2 is 1; f x3 is a binary function of the voltage of the battery cells in the battery pack. If any of the battery cell voltages is lower than the set voltage value, f x3 is 0, otherwise f x3 is 1.

[0008] Preferably, the charge and discharge management is charge and discharge management based on the three-phase power balance of the power inversion and grid connection of the battery pack, and the charge and discharge management calculates the upper limit and lower limit of the charge and discharge voltage of the battery pack based on the number of battery pack monomers and conducts control.

[0009] Preferably, the several battery packs include battery pack 1 and battery pack 2. The switching control device includes: a switch K41 connected in parallel with a diode and connected to the positive pole of bus 1, and the K41 is connected to the positive terminal of battery pack 1; a switch K21 connected to the positive pole of battery pack 1 and a switch K31 connected to the negative pole of battery pack 1, where the switch K21 is connected to the switch K41 and the positive pole of the load, and the switch K31 is connected to the negative pole of the load; a switch K42 connected in parallel with another diode and connected to the positive pole of bus 2, and the K42 is connected to the positive terminal of battery pack 2; a switch K22 connected to the positive pole of battery pack 2 and a switch K32 connected to the negative pole, where the switch K22 is connected to the switch K42 and the positive pole of the load, and the switch K33 is connected to the negative pole of the load; a switch K11 for controlling the on and off of the positive poles of bus 1 and bus 2; a switch K12 for controlling the on and off of the negative poles of bus 1 and bus 2.

[0010] Preferably, the buck-boost device includes: a programmable PWM module Q1 connected to the positive electrode of the battery pack; a programmable PWM module Q2 and a storage inductor connected to the programmable PWM module Q1; a programmable PWM module Q3 connected to the storage inductor and connected to the negative electrode of the battery pack in parallel with the programmable PWM module Q2; a programmable PWM module Q4 connected to the storage inductor and the programmable PWM module Q3, and the programmable PWM module Q4 is connected to the positive electrode of the DC terminal; the programmable PWM module Q2 and the programmable PWM module Q3 are connected to the negative electrode of the DC terminal.

[0011] Preferably, the online capacity verification, charging and discharging control system for the wide-voltage battery pack further includes a bidirectional converter device, which is connected to both the buck-boost device and the central controller simultaneously and is used for electrical isolation between direct current and alternating current.

[0012] Preferably, the online capacity verification, charging and discharging control system for the wide-voltage battery pack further includes a local touch display operation screen. The central controller records the real-time data during the operation process, outputs a report on the capacity verification, charging and discharging of the battery in the form of a chart, and sends it to the local touch display operation screen for display.

[0013] Preferably, the online capacity verification, charging and discharging control system for the wide-voltage battery pack further includes an alarm system, which is used to give an alarm when the total voltage of the battery pack or the temperature or voltage of the battery cells in the battery pack exceeds the set value.

[0014] Preferably, the online capacity verification, charging and discharging control system for the wide-voltage battery pack further includes a communication module, which is connected to both the central controller and an external network simultaneously and is used for data interaction and remote data storage to form various data reports remotely.

[0015] The beneficial effects of the present invention are as follows: Through the binary function logic, the present invention accurately evaluates the battery capacity; the setting of the buck-boost device ensures adaptation to a wide voltage range, and voltage adaptation can be achieved regardless of the voltage level of the battery pack, ensuring the safety of battery charging and discharging; the switching control device supports seamless switching of multiple battery packs to ensure uninterrupted power supply during online capacity verification. At the same time, the present invention records the real-time data of the entire operation process of the online capacity verification system for the wide-voltage battery pack in real time and outputs a report on the capacity verification, charging and discharging of the battery in the form of a chart, which can effectively help the operation and maintenance personnel for analysis and diagnosis. Through multi-dimensional innovation, the present invention significantly improves the capacity verification efficiency and system reliability and has important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of a system of the present invention; Figure 2 is a schematic diagram of the control switching process of the battery pack in the present invention; Figure 3It is a schematic diagram of the step-up and step-down process of the battery pack in the present invention; Figure 4 It is a schematic diagram of the working process of the bidirectional converter in the present invention; Figure 5 It is a principle block diagram of the switching control device in the present invention; Figure 6 It is a principle block diagram of the step-up and step-down device in the present invention. Detailed implementation manners

[0017] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more complete and will fully convey the concept of the example embodiments to those skilled in the art.

[0018] In addition, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. can be used. In other cases, well-known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of this application.

[0019] The block diagrams shown in the accompanying drawings are only functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0020] The flowcharts shown in the accompanying drawings are only illustrative and do not necessarily include all the content and operations / steps, nor do they necessarily have to be executed in the described order. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to the actual situation.

[0021] Embodiment: A wide-voltage battery pack online capacity verification and charge-discharge control system, as Figure 1 shown, includes: A single-cell detection module, connected to the central controller, for monitoring the voltage, temperature, and internal resistance data of the battery single cells and obtaining the number of battery single cells in the battery pack; A switching control device is connected to a number of battery packs and a central controller simultaneously, and is used to control the switching of the number of battery packs; a buck-boost device is connected to the switching control device and the central controller simultaneously, and is used to control the rise and fall of the voltage of the number of battery packs; a bidirectional converter device is connected to the buck-boost device and the central controller simultaneously, and is used for electrical isolation between direct current and alternating current; a central controller is used to control the switching control device and the buck-boost device by sending signals to achieve on-line capacity verification and charge and discharge management of a number of battery packs.

[0022] The on-line capacity verification performs capacity measurement of the battery pack according to the following formula: In the formula, f x1 is a binary function of the total voltage of the battery pack. If the total voltage of the battery pack exceeds the set voltage, then f x1 is 0, otherwise f x1 is 1; f x2 is a binary function of the temperature of the battery cells in the battery pack. If any of the battery cell temperatures exceeds the set temperature, f x2 is 0, otherwise f x2 is 1; f x3 is a binary function of the voltage of the battery cells in the battery pack. If any of the battery cell voltages is lower than the set voltage value, f x3 is 0, otherwise f x3 is 1.

[0023] The charge and discharge management is charge and discharge management based on the three-phase power balance of the power inversion and grid connection of the battery pack, and the charge and discharge management calculates the upper limit and lower limit of the charge and discharge voltage of the battery pack based on the number of battery pack monomers and conducts control.

[0024] As Figure 5 shown, the number of battery packs includes battery pack 1 and battery pack 2. The switching control device includes: a switch K41 connected in parallel with a diode and connected to the positive pole of bus 1, and the K41 is connected to the positive terminal of battery pack 1; a switch K21 connected to the positive pole of battery pack 1 and a switch K31 connected to the negative pole of battery pack 1, where the switch K21 is connected to the switch K41 and the positive pole of the load, and the switch K31 is connected to the negative pole of the load; a switch K42 connected in parallel with another diode and connected to the positive pole of bus 2, and the K42 is connected to the positive terminal of battery pack 2; a switch K22 connected to the positive pole of battery pack 2 and a switch K32 connected to the negative pole, where the switch K22 is connected to the switch K42 and the positive pole of the load, and the switch K33 is connected to the negative pole of the load; a switch K11 for controlling the on-off of the positive poles of bus 1 and bus 2; a switch K12 for controlling the on-off of the negative poles of bus 1 and bus 2.

[0025] The described buck-boost device includes: a programmable PWM module Q1 connected to the positive pole of the battery pack; a programmable PWM module Q2 and an energy storage inductor connected to the programmable PWM module Q1; a programmable PWM module Q3 connected to the energy storage inductor and connected to the negative pole of the battery pack in parallel with the programmable PWM module Q2; a programmable PWM module Q4 connected to the energy storage inductor and the programmable PWM module Q3, and the programmable PWM module Q4 is connected to the positive pole of the DC terminal; the programmable PWM module Q2 and the programmable PWM module Q3 are connected to the negative pole of the DC terminal.

[0026] The wide-voltage battery pack online capacity verification and charge-discharge control system further includes a local touch display operation screen. The central controller records the real-time data during the operation process, outputs a report on the capacity verification, charge, and discharge of the battery in the form of a chart, and sends it to the local touch display operation screen for display.

[0027] The wide-voltage battery pack online capacity verification and charge-discharge control system further includes an alarm system, which is used to issue an alarm when it detects that the total voltage of the battery pack or the temperature or voltage of the battery monomers in the battery pack exceeds the set value.

[0028] The wide-voltage battery pack online capacity verification and charge-discharge control system further includes a communication module, which is connected to both the central controller and an external network at the same time, and is used for data interaction and remote data storage to form various data reports remotely.

[0029] The capacity verification, charge, and discharge of the battery is a two-way energy transfer process. When the battery discharges, the energy of the battery is transferred to the alternating current, and the DC energy of the battery is converted into AC energy. For the safety of the equipment, electrical isolation is adopted between the alternating current and the direct current, and the electrical isolation link is implemented in the bidirectional converter part. Implementing it in the converter part is because the converter part works at a higher voltage. Under the same power, a relatively small transformer can be used at a higher voltage, saving the investment in equipment. Of course, it also reduces the volume of the product. According to Figure 1 , describe the charge-discharge process of the -48V communication battery. The DC voltage of the battery pack is -48V (the positive pole is grounded, and the problem of positive pole grounding does not need to be considered during the charge and discharge of the battery). After the dual battery packs in mutual backup pass through the switching control device, only one battery pack enters the state of capacity verification, charge, and discharge, and the backup battery pack is switched to the -48V DC bus of the original battery pack.

[0030] Obviously, the voltage of the 48V battery pack needs to pass through a boost circuit to meet the DC voltage requirement for inverter grid connection.

[0031] The battery voltage of 48V, through the internal buck-boost device, commands this buck-boost device to work in the boost mode. The voltage is boosted to 280V through this buck-boost device. This 280V DC voltage enters the bidirectional converter device. Inside the converter device, through the DC / DC full-bridge circuit, this voltage is converted into a DC voltage of 400V. This voltage undergoes PWM chopping processing to obtain an AC power output of 220V. Here, the 400V DC voltage is adopted because in some places where the AC voltage may be relatively high and energy needs to be output, after PWM chopping, an AC voltage as high as 280V can still be output. Of course, in actual applications, the voltage variation range of the AC 220V is generally set within the voltage range of ~176V to ~264V to avoid problems caused by too high voltage; Charging the -48V battery, and the charging energy comes from the AC power supply. The AC power supply of ~220V, through Figure 1 the bidirectional converter device, can convert the AC power into a DC power of 400V. The 400V DC power, under the action of the internal DC / DC full bridge, becomes a DC voltage output of 280V. The 280V DC voltage, through the buck-boost device, at this time, the buck-boost device works in the buck mode and can output the charging voltage of the -48V battery.

[0032] The voltage of the -48V battery pack is between -43.2V and -56.4V. After the battery pack discharges, the voltage of the battery pack is relatively low. The buck-boost device can control the output of the battery charging voltage according to the magnitude of the battery charging current to ensure that the battery pack is in a safe charging state.

[0033] The above describes the working condition of the circuit when the voltage of the battery pack is relatively low.

[0034] Then, the charge and discharge of the 480V battery pack are used for the control method of the wide-voltage battery pack on-line capacity verification system of the present invention.

[0035] For the 480V battery pack, during the actual working process, when the battery pack is in the equalizing charge state, the voltage reaches 564V, and when it is in the floating charge state, the voltage also reaches 544V. After the battery pack is disconnected from the DC bus and is in a static state, the voltage at this time, the voltage of the battery pack is about 510V.

[0036] When discharging the 480V battery pack, through Figure 1 it can be known that the buck-boost module needs to work in the buck state to reduce the voltage of the 480V battery pack to 280V. This reduced voltage enters Figure 1 the bidirectional circulating device, and through the action of the circulating device, the energy of the 480V battery pack is output to the grid AC ~220V for grid connection.

[0037] When charging the 480V battery pack, the working mode is basically the same as the above description and will not be elaborated here.

[0038] The description of the charging and discharging process of the battery pack between the 48V and 480V voltage levels is also basically the same as the above description.

[0039] From Figure 2 it can be seen that after processes S0002 and S0003, the battery pack has been disconnected from the bus state and can enter the charging and discharging of the battery pack.

[0040] The total voltage acquisition of the battery pack, the individual voltage acquisition of the battery pack, and the temperature acquisition of the individual battery cells of the battery pack are all related data for the capacity verification charging and discharging of the battery pack. S0004 and S0005 are important links for obtaining battery pack information, and the subsequent charging and discharging of the battery pack rely on these data.

[0041] In step S0006, it can be found whether the connection, testing, and measurement of the battery pack are accurate. If the connection is not good, an alarm will be output and the execution of the capacity verification charging and discharging will be terminated. Only after a safe and reliable connection can the next link be entered.

[0042] The present invention can realize the automatic coding of the individual modules of the battery pack, automatically obtain the number of individual battery cells of the battery pack. After the number of individual battery cells of the battery pack is determined, the total voltage of the battery pack can be automatically calculated. By comparing the accumulated voltage of the individual battery cells of the battery pack with the data of the total voltage acquisition of the battery pack, a judgment basis for whether the battery pack is correctly connected can be obtained.

[0043] In the DC system, the number of individual battery cells of the -48V communication power supply is fixed at 24 2V individual battery cells connected in series, and there will be no situation where a battery pack is composed of 23 or 25 individual battery cells. For the 110V operating power supply, 54 2V individual battery cells are usually connected in series in normal use, and in some occasions, 52 2V xdc individual battery cells are connected in series. For the 220V DC system, the number of individual battery cells varies from 102 to 108. The 380V and 480V UPS battery packs generally use 12V individual battery cells, and the number is relatively fixed.

[0044] The present invention adopts the method of automatically numbering the individual battery cells, can automatically obtain the number of individual battery cells, and provides scientific charging and discharging voltage data for the charging and discharging of the battery pack, avoiding safety problems caused by too high or too low charging voltage of the battery pack.

[0045] Automatically adapting the charging and discharging voltages of the battery pack generally follows the following mode: The voltage of the floating charge of the battery pack is the number of battery cells N * 2.25V. For a battery pack composed of 12V battery cells, 12V battery cells are equal to 6 2V cells, and there will be no problem with this calculation.

[0046] The equalizing charge voltage of the battery pack is the number of battery cells N * 2.35V, which is also the highest charging voltage of the battery pack. Under any circumstances, it is not allowed for the charging voltage of the battery pack to exceed N * 2.35V; Please refer to Figure 3 and Figure 6 , Figure 6 is a bidirectional DC energy transfer circuit that can perform step-up and step-down processing.

[0047] When the voltage of the battery pack is lower than 280V, the circuit operates in a step-up discharge state.

[0048] The working steps of the devices in the battery discharge state are as follows: Figure 6 Q1 of conducts, Q2 cuts off, Q3 is controlled by the MCU with an adjustable duty cycle output of PWM3 to charge and discharge the inductor, and Q4 is used as a rectifier diode at this time. Under the action of PWM, the battery terminal voltage outputs energy at the 280V DC terminal.

[0049] According to Figure 6 , the working steps for charging a battery pack with a voltage lower than 280V are as follows: Figure 6 Q1 of conducts, Q2 cuts off, Q4 is controlled by the MCU with an adjustable duty cycle output of PWM4 to charge and discharge the inductor, and Q3 is used as a freewheeling diode at this time. Under the action of PWM, the battery terminal voltage obtains the voltage and power required for charging the battery pack.

[0050] When the voltage of the battery pack is higher than 280V, the circuit operates in a step-down discharge state.

[0051] At this time, the working steps of the devices in the battery discharge state are as follows: Figure 6 Q4 of conducts, Q3 cuts off, Q1 is controlled by the MCU with an adjustable duty cycle output of PWM3 to charge and discharge the inductor, and Q2 is used as a rectifier diode at this time. Under the action of PWM, the battery terminal voltage outputs energy at the 280V DC terminal.

[0052] According to Figure 6 , the working steps for charging a battery pack with a voltage higher than 280V are as follows: Figure 6Q4 conducts, Q3 cuts off, Q2 is controlled by the MCU with an adjustable duty cycle output of PWM4 to charge and discharge the inductor. At this time, Q2 is used as a rectifier diode. Under the action of PWM, the battery terminal voltage obtains the voltage and power required for charging the battery pack.

[0053] According to Figure 1 and Figure 3 , the output voltage of this buck-boost device is set to 280V, indicating that the buck-boost module needs to have a very wide voltage change range. S0011 first obtains the voltage information of the battery pack, and S0012 determines the working mode of the buck-boost device according to this information. S0013 and S0014 determine whether the circuit works in the boost or buck mode. This process is also automatically detected and controlled by the central controller.

[0054] The single-module power of this buck-boost device is set at 5KW, and multi-module power combination is supported internally.

[0055] The battery capacity of the battery pack is large, and there will be a large difference in the number of power module configurations of this buck-boost device. At present, the capacity of a single battery cell ranges from 200AH to 3000AH, the charge and discharge current of the battery pack ranges from 20A to 300A, and the power difference also reaches 15 times.

[0056] In actual use, for the module configuration of the buck-boost device in a 220V DC power supply of a certain power plant, a 2600AH battery pack is used. Considering the highest voltage of the battery pack and partial power redundancy design, 16 modules are designed to be used for power combination to achieve battery energy transfer of more than 80KW.

[0057] See Figure 4 , the technology of the bidirectional converter is relatively mature, and a full-bridge circuit between 280V and 400V DC is adopted. The main reasons for adopting this circuit are, firstly, to solve the physical isolation between AC and DC and the safety isolation problem of the wide-voltage battery pack online capacity verification system itself. Secondly, by using a DC / DC full-bridge circuit with a relatively small conversion ratio, a higher DC / DC conversion efficiency can also be obtained.

[0058] The single-module power of the bidirectional converter device is also positioned at 5KW. In actual use, the configuration data of this bidirectional converter device module is also configured according to the charge and discharge power of the battery pack of the battery. Its configuration quantity is basically consistent with the number of modules of the buck-boost device.

[0059] Other embodiments of the present application will be readily contemplated by those skilled in the art after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common general knowledge or conventional technical means in the technical field not disclosed in the present application.

[0060] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. An online capacity verification and charge-discharge control system for a wide voltage battery pack, characterized in that: include: The cell detection module is connected to the central controller and is used to monitor the voltage, temperature, and internal resistance data of the battery cells and obtain the number of battery cells in the battery pack; A switching control device is connected to the plurality of battery packs and the central controller at the same time, and is used to control the switching of the plurality of battery packs; The step-up and step-down device is connected to the switching control device and the central controller at the same time, and is used to control the step-up and step-down of the voltage of several battery groups; the central controller is used to control the switching control device and the step-up and step-down device by sending signals to realize the online core capacity and the charge and discharge management of several battery groups.

2. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: The online capacity verification is performed according to the following formula to measure the capacity of the battery pack: In the formula, f x1 is a binary function of the total voltage of the battery pack. If the total voltage of the battery pack exceeds the set voltage, then f x1 is 0, otherwise f x1 is 1; f x2 It is a binary function of the temperature of the battery cells in the battery pack. If any of the battery cell temperatures exceeds the set temperature, f x2 is 0, otherwise f x2 is 1; f x3 It is a binary function of the voltage of the battery cells in the battery pack. If any voltage of the battery cell is lower than the set voltage value, f x3 is 0, otherwise f x3 is 1.

3. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: The charge and discharge management is based on the three-phase power balance of the battery pack power inverter grid connection, and the charge and discharge management calculates the upper and lower limits of the battery pack charge and discharge voltage based on the number of battery cells and controls them.

4. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: The plurality of battery packs include battery pack 1 and battery pack 2, and the switching control device includes: a switch K41 connected in parallel with a diode and connected to the positive pole of bus 1, wherein K41 is connected to the positive terminal of battery pack 1; a switch K21 connected to the positive pole of battery pack 1 and a switch K31 connected to the negative pole of battery pack 1, wherein the switch K21 connects the switch K41 and the positive pole of the load, and the switch K31 connects the negative pole of the load; a switch K42 connected in parallel with another diode and connected to the positive pole of bus 2, wherein K42 is connected to the positive terminal of battery pack 2; a switch K22 connected to the positive pole and a switch K32 connected to the negative pole of battery pack 2, wherein the switch K22 connects the switch K42 and the positive pole of the load, and the switch K33 connects the negative pole of the load; a switch K11, used to control the on and off of the positive poles of bus 1 and bus 2; a switch K12, used to control the on and off of the negative poles of bus 1 and bus 2.

5. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: The step-up and step-down device includes: a program-controlled PWM module Q1 connected to the positive electrode of a battery pack; a program-controlled PWM module Q2 and an energy storage inductor connected to the program-controlled PWM module Q1; a program-controlled PWM module Q3 connected to the energy storage inductor and connected in parallel with the program-controlled PWM module Q2 and then connected to the negative electrode of the battery pack; a program-controlled PWM module Q4 connecting the energy storage inductor and the program-controlled PWM module Q3, the program-controlled PWM module Q4 being connected to the positive electrode of the DC terminal; the program-controlled PWM module Q2 and the program-controlled PWM module Q3 being connected to the negative electrode of the DC terminal.

6. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: It also includes a bidirectional converter device, which is connected to the step-up and step-down device and the central controller and is used for electrical isolation of direct current and alternating current.

7. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: It also includes a local touch display operation screen. The central controller records real-time data of the operation process, and outputs a report on the battery capacity charging and discharging in the form of a chart and sends it to the local touch display operation screen for display.

8. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: It also includes an alarm system for issuing an alarm when it is detected that the total voltage of the battery pack or the temperature or voltage of the battery cells in the battery pack exceeds a set value.

9. The wide voltage battery pack online capacity verification and charge-discharge control system according to claim 1 is characterized in that: It also includes a communication module, which is connected to the central controller and the external network at the same time, and is used for data interaction and remote data storage, and for forming various data reports remotely.

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