Direct-current bus-based series formation and capacity grading production testing system

Abstract

Disclosed in the present invention is a common bus-based series formation and capacity grading production testing system, which comprises an alternating-current power grid, a PCS device, a common direct-current bus, a capacity grading part direct-current bus, a formation part direct-current bus, a formation master control box, a capacity grading master control box, series capacity grading devices of a capacity grading line, and series formation devices of a formation line. The PCS device is separately connected to the alternating-current power grid and the common direct-current bus. The common direct-current bus is separately connected to the formation master control box and the capacity grading master control box. The series capacity grading devices of the capacity grading line are separately connected to the capacity grading master control box and the capacity grading part direct-current bus. The series formation devices of the formation line are separately connected to the formation master control box and the formation part direct-current bus. In the present invention, the whole production line uses one PCS, and each independent device is directly connected to the common direct-current bus, so that during operation, electric energy fed back by batteries undergoing formation and capacity grading is preferentially used by other formation and capacity grading devices on the common bus, thus reducing the number of electric energy conversions in charge-discharge cycles, improving the power utilization efficiency and reducing electric energy loss.

Description

A DC bus-based series component capacity production detection system Technical Field

[0001] The present invention relates to the technical field of battery capacity division, and in particular to a series capacity division production and detection system based on a DC bus. Background Art

[0002] The formation and capacity separation process is the core process of the lithium battery. There are multiple charge and discharge processes in the formation and capacity separation process.

[0003] A lot of electricity will be consumed in the process. The series component capacity technology is a new detection technology developed in recent years.

[0004] The technology connects dozens or even hundreds of batteries in series for charging and discharging, and has the characteristics of high charging and discharging efficiency and good current consistency.

[0005] The bidirectional power conversion part of series-connected capacity-sharing technology is mainly divided into bidirectional ACDC module and bidirectional DCDC module.

[0006] ACDC is used to convert 380V AC into DC (generally between 600V and 800V, which can be set), while DCDC implements high-precision constant current control to charge and discharge the series-connected batteries. In actual application, there are many formation and capacity division equipment on the production line. At the same time, some equipment is charging the series-connected capacity division battery pack, while some equipment is discharging the series-connected capacity division battery pack. These equipment are connected through 380V cables in the factory and use this as the collection point (AC bus) for power conversion.

[0007] When charging the device or capacity-dividing device, power is taken from the 380V AC bus and then passed through the ACDC and DCDC in the device to charge and discharge the series battery pack; when discharging, the energy of the battery pack is sent to the 380V AC bus through the DCDC and then the ACDC inverter.

[0008] The applicant's research has found that in existing production line capacity splitting and testing systems, all battery charge and discharge paths include ACDC and DCDC, which increases the number of feedback energy conversions during battery discharge and reduces system efficiency. Furthermore, when the charge and discharge currents are low, the existing series capacity splitting technology results in low total power consumption per device and low overall conversion efficiency. Summary of the Invention

[0009] In order to overcome the above technical defects and further improve the system power efficiency of the existing lithium battery capacity production line, the present invention provides

[0010] A production and detection system based on the series connection of DC busbars is provided. In order to solve the above problems, the present invention is implemented according to the following technical solutions:

[0011] In the first aspect, the present invention provides a production and detection system based on the series connection of DC busbars.

[0012] The system comprises: an AC power grid, a PCS device, a common DC bus, a DC bus of a capacity division part, a DC bus of a formation part, a formation master control box, a capacity division master control box, a series capacity division device of a capacity division line, and a series formation device of a formation line; the PCS device is connected to the AC power grid and the common DC bus respectively, the common DC bus is connected to the formation master control box and the capacity division master control box respectively, the series capacity division device of the capacity division line is connected to the capacity division master control box and the DC bus of the capacity division part respectively,

[0013] The series forming equipment of the forming line is respectively connected to the forming master control box and the DC bus of the forming section; wherein,

[0014] The PCS device is a bidirectional power conversion unit used to rectify three-phase AC power into DC power or invert DC power into three-phase AC power;

[0015] The formation master control box is used to control the connection between the formation unit DC bus and the public DC bus;

[0016] The sub-capacity master control box is used to control the connection between the sub-capacity DC bus and the common DC bus;

[0017] The series capacity separation equipment of the capacity separation line is a device used for lithium battery capacity separation in the production line, and the series formation equipment of the formation line is a device used for lithium battery formation in the production line;

[0018] The series capacity division equipment and the series formation equipment are a complete set of automated intelligent production and testing devices, both including a bidirectional power conversion circuit, a needle bed and a control system, and are used for series connection of lithium batteries for capacity division.

[0019] Preferably, the PCS device is a bidirectional power conversion unit, including one PCS unit, or multiple PCS units working in parallel, wherein the PCS unit includes a three-phase power frequency transformer, a bidirectional ACDC converter, a DC switch, and a control and indication part. The primary side of the three-phase power frequency transformer is connected to the AC power grid, and the secondary side is connected to the bidirectional ACDC converter, which plays an isolation and step-up / down role. The primary side voltage range is 200V~35000V, and the secondary side voltage is 200V~1000V. The bidirectional ACDC converter is a non-isolated type. The bidirectional ACDC converter is connected to the DC switch, and the DC switch is connected to the common DC bus.

[0020] Preferably, the PCS device is a bidirectional power conversion unit, including one PCS unit, or multiple PCS units working in parallel, wherein the PCS unit includes one or more bidirectional ACDC converter modules, a DC switch, a control and indication part,

[0021] The bidirectional ACDC converter module is a high-frequency isolated type with multiple parallel outputs. The parallel input end of the bidirectional ACDC converter module is connected to the AC grid, and the parallel output end is connected to the DC switch, and the DC switch is connected to the common DC bus.

[0022] Preferably, the PCS device is a bidirectional power conversion unit, including one PCS unit, or multiple PCS units working in parallel, wherein the PCS unit includes an industrial frequency transformer, multiple bidirectional ACDC converter modules, a DC switch, and a control and indication part. Multiple bidirectional ACDC converter modules work in parallel, the primary side of the industrial frequency transformer is connected to the AC power grid, and the secondary side is connected to the parallel input end of the bidirectional ACDC converter module, which plays an isolation and voltage step-up / down role. The primary side voltage range is 200V~35000V, and the secondary side voltage is 200V~1000V. The bidirectional ACDC converter module is a high-frequency isolation type, and the parallel output end of the bidirectional ACDC converter module is connected to the DC switch, and the DC switch is connected to the common DC bus.

[0023] Preferably, the sub-capacity master control box includes a DC switch, a switch monitoring module, and a switch status display unit, wherein:

[0024] The DC switch is used to control the connection between the common DC bus and the capacity-divided DC bus. The capacity-divided master control box is controlled by the DC switch.

[0025] The connection between the DC bus of the capacity division part and the common DC bus, the said capacity division master control box is used for power supply control and indication of the DC bus of the capacity division part and the series capacity division equipment;

[0026] The formation master control box includes a DC switch, a switch monitoring module, and a switch status display unit, wherein the DC switch is used to control the connection between the public DC bus and the formation DC bus. The formation master control box controls the DC bus of the formation part through the DC switch.

[0027] The busbar is connected to the public DC busbar, and the main forming control box is used for power supply control and indication of the forming part DC busbar and series forming equipment.

[0028] Preferably, when only the DC switch of the formation master control box or the capacity division master control box is closed, the common DC bus is connected to the DC bus of the formation part or the common DC bus is connected to the DC bus of the capacity division part, and the series formation equipment or the series capacity division equipment can work.

[0029] When the DC switches in the formation main control box and the capacity division main control box are closed, the common DC bus and the capacity division DC

[0030] The busbars are connected as one, and the common DC busbar and the DC busbar of the forming part are connected as one, so that the series forming equipment and the series capacity dividing equipment can work.

[0031] Preferably, the bidirectional power conversion circuit in the series capacity division device is connected to the DC bus of the capacity division part and the battery part controlled in series, and performs a capacity division process on the series-connected batteries, including multiple charging and discharging;

[0032] The bidirectional power conversion circuit in the series formation equipment is connected to the DC bus of the formation part and the battery part controlled in series, and performs a formation process on the series-connected batteries, including multiple charging.

[0033] Preferably, the series battery includes N cells that are formed and divided into different capacities, and the N cells are connected by a formation and capacity division device.

[0034] The internal control forms a series loop, where N is an integer greater than or equal to 8 and less than or equal to 256; the battery in the series battery refers to the battery that needs to be charged and discharged in the formation process and the capacity division process.

[0035] Preferably, when the series capacity dividing equipment and the series formation equipment in the chemical capacity dividing production line are performing capacity dividing and formation respectively, the equipment performs charging and discharging operations, wherein the equipment performing the discharge operation feeds back electric energy to the common DC bus, i.e., the feedback electric energy of the DC bus.

[0036] The charging equipment obtains electrical energy from the public DC bus, i.e., the electrical energy consumed by the DC bus. The electrical energy flowing through the PCS equipment in the system is the difference between the feedback energy of the DC bus and the electrical energy consumed by the DC bus. The PCS operating state is automatically adjusted according to the difference between the feedback energy of the DC bus and the electrical energy consumed by the DC bus. The PCS operating states include rectification state, inversion state, idle state, and no-load state.

[0037] Preferably, when the power consumed on the common DC bus is greater than the feedback power, the difference in power is fed through the common DC bus.

[0038] The PCS device draws power from the AC power grid, and the PCS working state is the rectification state;

[0039] When the power consumed on the public DC bus is less than the fed-back power, the difference is fed back to the AC grid via the public DC bus through the PCS device, and the PCS is in the inverter state.

[0040] When the consumed electric energy on the common DC bus is equal to the fed-back electric energy, no electric energy flows between the common DC bus and the PCS equipment, and the PCS working state is an idle state;

[0041] When all the series forming devices and series capacity dividing devices on the common DC bus are not performing charging or discharging operations, the PCS operating state is a no-load state.

[0042] Compared with the existing technology, the beneficial effects of the present invention are: the present invention separates the ACDC part (380V to 700V) of the dual power conversion part in the conventional capacity-sharing equipment, and the entire production line uses one set of PCS. The AC

[0043] The power grid can be from a 380V low voltage grid to a 35kV high voltage grid. The new series-connected capacity-sharing equipment is connected to a public DC bus (voltage of about 200~1500V, adjustable). As a result, the production line architecture is transformed from the original AC bus to a public DC bus.

[0044] In terms of the overall charging and discharging efficiency of the component capacity production line, compared with the high charging and discharging efficiency of the original series equipment, the conversion path of the feedback electric energy through ACDC-AC bus-ACDC is reduced, the electric energy conversion is reduced, and the cyclic charging and discharging efficiency is significantly improved; the PCS of the public DC bus operates at a relatively good load level, with high charging and discharging efficiency, improving the power quality of the AC power grid in the factory. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0046] FIG1 is a structural diagram of a series-connected capacity production and detection system based on a DC bus according to an embodiment of the present invention;

[0047] FIG2 is a topological diagram of a series connection of a common DC bus and a series-connected capacity-splitting device according to an embodiment of the present invention;

[0048] FIG3 is a diagram of a series-connected component capacity production detection system based on a DC bus according to an embodiment of the present invention and a conventional series-connected component capacity production detection system based on a DC bus according to an embodiment of the present invention.

[0049] Schematic diagram of the battery charge to discharge energy path of the capacity production detection system;

[0050] FIG4 is a diagram illustrating the principle of power conversion in a production and detection system based on series connection of DC buses according to an embodiment of the present invention;

[0051] FIG5 is a diagram illustrating a first structural example of a PCS device according to an embodiment of the present invention;

[0052] FIG6 is a diagram illustrating a second structural example of a PCS device according to an embodiment of the present invention;

[0053] FIG7 is a diagram illustrating a third structural example of a PCS device according to an embodiment of the present invention;

[0054] FIG8 is a diagram illustrating the principle of power conversion in a system in a first rectification state according to an embodiment of the present invention;

[0055] FIG9 is a diagram illustrating the principle of power conversion in a system in a second rectification state according to an embodiment of the present invention;

[0056] FIG10 is a diagram illustrating the principle of power conversion in a system in an inverter state according to an embodiment of the present invention;

[0057] FIG11 is a diagram illustrating the principle of power conversion in a system in an idle state according to an embodiment of the present invention;

[0058] FIG12 is a structural diagram of another embodiment of the present invention based on the series connection of DC bus capacity production detection system;

[0059] 13 is a structural diagram of a DC bus-based series formation production detection system according to an embodiment of the present invention;

[0060] FIG14 is a structural diagram of a series capacity-divided production detection system based on a DC bus according to an embodiment of the present invention;

[0061] FIG15 is a structural diagram of another DC bus-based series capacity division production and detection system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0063] With the development of future technology, various electronic products and new energy vehicles are widely used in people's daily lives. In particular, in recent years, the rapid development of new energy vehicles and new electrochemical energy storage has led to a rapid increase in demand for power batteries and energy storage batteries.

[0064] The formation and capacity grading processes are core back-end steps in lithium batteries. These processes involve multiple charge and discharge cycles, consuming significant amounts of energy. Simply put, formation activates the battery, while capacity grading is used to grade and tier the batteries. Series capacity grading technology, a recent development, connects dozens or even hundreds of batteries in series before charging and discharging, offering high charge and discharge efficiency and excellent current consistency.

[0065] The energy conversion portion of the series-connected capacity-fractionating technology primarily includes bidirectional ACDC and bidirectional DCDC. The bidirectional ACDC is used to rectify 380V AC to DC (typically between 600V and 800V, adjustable) or invert DC to 380V AC. The bidirectional DCDC implements high-precision constant current control to charge or discharge the series-connected batteries. When charging, the batteries draw energy from the 380V grid through the ACDC and DCDC systems. During discharge, the battery energy is fed back to the 380V grid through the ACDC and DCDC systems for use by other electrical devices.

[0066] Compared with the parallel (5V) capacity-combining technology, the series capacity-combining technology has the advantages of high charging and discharging efficiency.

[0067] In actual application, there are many devices in the formation and capacity separation processes in the lithium battery automation production line. At the same time, some formation equipment and capacity separation equipment will be charging the battery (referred to as charging equipment for short), some formation equipment or capacity separation equipment will be discharging the battery (referred to as discharging equipment for short), and some equipment will be in a dormant (or shelved) or loading state, that is, the equipment is not charging or discharging (this part has no effect on the power analysis and will be ignored in the following text).

[0068] These charging and discharging devices are all connected via 380V cables within the factory, with the 380V AC bus serving as the convergence point for power conversion. Therefore, it can be assumed that the conventional formation equipment and capacity-dividing equipment share the same AC bus. All devices charging or discharging the batteries require bidirectional conversion via a bidirectional ACDC system and a subsequent bidirectional DCDC system. In this system, the battery discharge energy path is from discharge device 1 (battery bank 1 - DCDC - ACDC) - 380V bus - charging device 2 (ACDC - DCDC - battery bank 2). From battery bank to battery bank, there are two DCDC conversion losses and two ACDC conversion losses.

[0069] In order to further reduce the energy consumption of the formation and capacity division process, based on the existing high efficiency of series formation and capacity division charge and discharge,

[0070] In order to further improve the charging and discharging efficiency of the chemical composition production line, the present invention studies and develops a series chemical composition production detection system based on a DC bus.

[0071] When all devices are working, they are connected through ACDC and then DCDC to charge and discharge the series battery pack.

[0072] For this equipment, the most critical component is the DC-DC (direct current-to-voltage) control, which is also essential. The AC-DC function is separated from the conventional forming and sizing equipment and replaced with a single high-power AC-DC system, or a common PCS. This system, combined with the new common-bus forming and sizing equipment, forms a system. In this new system, the battery discharge energy path is from discharge device 1 (battery pack 1 - DC-DC) - DC bus - charging device 2 (DCDC - battery pack 2). The remaining energy is discharged through the PCS, reducing the A-DC conversion losses twice between battery packs. This improves the system energy conversion efficiency of the forming and sizing lines while reducing the use of busbar cables. Furthermore, this system architecture allows the PCS to operate at an optimal power level, improving system stability and AC grid power quality.

[0073] This solution can further improve the system efficiency of existing chemical fractionation equipment. This solution is not only applicable to series chemical fractionation systems, but also to parallel chemical fractionation systems.

[0074] As shown in Figure 1, a DC bus-based series-connected capacity-splitting production and testing system includes: an AC power grid, PCS equipment, a common DC bus, a capacity-splitting unit DC bus, a forming unit DC bus, a forming master control box, a capacity-splitting master control box, series-connected capacity-splitting equipment for the capacity-splitting lines, and series-connected forming equipment for the forming lines. The PCS equipment is connected to the AC power grid and the common DC bus, respectively. The common DC bus is connected to the forming master control box and the capacity-splitting master control box, respectively. The series-connected capacity-splitting equipment for the capacity-splitting lines is connected to the capacity-splitting master control box and the capacity-splitting unit DC bus, respectively. The series-connected forming equipment for the forming lines is connected to the forming master control box and the forming unit DC bus, respectively. The PCS equipment is a bidirectional power conversion unit used to rectify three-phase AC power into DC power or to invert DC power into three-phase AC power.

[0075] The formation master control box is used to control the connection between the formation unit DC bus and the public DC bus;

[0076] The capacity division master control box is used to control the connection between the capacity division DC bus and the public DC bus;

[0077] The series capacity separation equipment in the capacity separation line is the equipment used for lithium battery capacity separation in the production line, and the series formation equipment in the formation line is the equipment used for lithium battery formation in the production line;

[0078] The series capacity division equipment and series formation equipment are a complete set of automated intelligent production and testing devices, both of which include a bidirectional power conversion circuit, a needle bed and a control system, and are used for the capacity division of series lithium batteries.

[0079] The series capacity division equipment and series formation equipment in this system form a complete set of independent testing equipment, including the power supply, bed-of-nails, and battery series control. The specific series power topology is shown in Figure 2. The power supply mainly includes a bidirectional DC-DC module, which is used to form or divide the capacity of lithium batteries (tray-loaded).

[0080] Furthermore, the present invention is a series-type component production detection system based on DC bus and conventional series-type component production

[0081] The schematic diagram of the battery discharge to charge energy path of the detection system is shown in Figure 3. The left side is a schematic diagram of the battery discharge to charge energy path of the conventional series-type production detection system, and the right side is a schematic diagram of the battery discharge to charge energy path of the series-type production detection system based on a DC bus of the present invention.

[0082] Schematic diagram of the path from battery discharge to energy charging.

[0083] The PCS is a bidirectional power conversion unit that performs AC / DC conversion and connects the three-phase AC grid to the public DC bus. It typically consists of a power frequency isolation transformer, a bidirectional A / D converter, AC / DC switches, and control and indication components. It automatically operates in rectification or inversion based on the power level on the public DC bus, and controls power factor, voltage harmonics, and current harmonics to ensure power quality on the three-phase AC grid.

[0084] In the series-connected capacity production and detection system of the present invention, the output of the PCS is a common DC bus.

[0085] The changing principle is shown in Figure 4.

[0086] In a specific embodiment, the PCS device is a bidirectional power conversion unit, including one PCS unit, or multiple PCS units operating in parallel. The PCS unit includes a three-phase power frequency transformer, a bidirectional ACDC converter, a DC switch, and a control and indication unit. As shown in Figure 5, the primary side of the three-phase power frequency transformer is connected to the AC grid, and the secondary side is connected to the bidirectional ACDC converter.

[0087] It plays the role of isolation and voltage step-up and step-down. The primary voltage range is 200V~35000V (generally 380V / 10kV), and the secondary voltage is 200V~1000V (generally 380V). The bidirectional ACDC converter is non-isolated. The bidirectional ACDC converter is connected to the DC switch, and the DC switch is connected to the public DC bus.

[0088] In another specific embodiment, the PCS device is a bidirectional power conversion unit, including one PCS unit, or multiple PCS units working in parallel. The PCS unit includes one or more bidirectional ACDC converter modules, DC switches, control and indication

[0089] As shown in Figure 6, the bidirectional ACDC converter module is a high-frequency isolated type with multiple parallel outputs. The parallel input end of the bidirectional ACDC converter module is connected to the AC grid, the parallel output end is connected to the DC switch, and the DC switch is connected to the public DC bus.

[0090] In another specific embodiment, the PCS device is a bidirectional power conversion unit, including one PCS unit or multiple PCS units operating in parallel. The PCS unit includes an industrial frequency transformer, multiple bidirectional ACDC converter modules, a DC switch, and a control and indication unit. As shown in Figure 7, the multiple bidirectional ACDC converter modules operate in parallel. The primary side of the industrial frequency transformer is connected to the AC grid, and the secondary side is connected to the parallel input of the bidirectional ACDC converter module, providing isolation and voltage step-up / step-down. The primary side voltage range is 200V to 35,000V (typically 380V / 10kV), and the secondary side voltage range is 200V to 1,000V (typically 380V). The bidirectional ACDC converter modules are high-frequency isolated. The parallel outputs of the bidirectional ACDC converter modules are connected to the DC switch, which is then connected to a common DC bus.

[0091] In actual application, PCS equipment is a bidirectional power conversion unit, including power frequency isolation transformer, bidirectional ACDC converter module, AC / DC switch, control and indication part, wherein the power frequency isolation transformer connects the three-phase AC grid and the bidirectional ACDC converter module.

[0092] The converter module plays the role of isolation and step-up / down. The bidirectional ACDC converter module can realize high-power PCS by parallel connection. Specifically, the bidirectional ACDC converter module can be a non-isolated bidirectional ACDC converter or an isolated bidirectional ACDC converter. The non-isolated bidirectional ACDC converter must be equipped with an industrial frequency isolation transformer, and the isolated bidirectional ACDC converter must be equipped with an industrial frequency isolation transformer.

[0093] The power frequency isolation transformer is only configured when voltage step-up or step-down is required. In a specific embodiment, the capacity-dividing main control box includes a DC switch, a switch monitoring module, and a switch status display unit.

[0094] Among them, the DC switch is used to control the connection between the common DC bus and the capacity-dividing DC bus. The capacity-dividing master control box controls the connection between the capacity-dividing DC bus and the common DC bus through the DC switch. The capacity-dividing master control box is used for power supply control and indication of the capacity-dividing DC bus and the series capacity-dividing equipment.

[0095] The formation master control box includes a DC switch, a switch monitoring module, and a switch status display unit. The DC switch is used to control the connection between the public DC bus and the formation DC bus. The formation master control box controls the formation DC bus through the DC switch.

[0096] The main forming control box is connected to the public DC bus and is used for power supply control and indication of the forming unit DC bus and series forming equipment.

[0097] Specifically, the main formation control box or the capacity division main control box is mainly responsible for the connection and control between the PCS and all series formation equipment of the formation line or all capacity division equipment of the capacity division line, and mainly includes a DC switch, a switch monitoring module, a switch status display unit, etc.

[0098] When the DC switch is open, all series forming devices of the forming line or all capacity dividing devices of the capacity dividing line are disconnected from the PCS; when the DC switch is closed, all series forming devices of the forming line or all capacity dividing devices of the capacity dividing line are connected to the PCS, and the public DC bus is directly connected to the DC bus of the forming line or the DC bus of the capacity dividing line.

[0099] In a specific embodiment, when only one of the DC switches of the formation master control box or the capacity division master control box is closed, the common DC bus is connected to the formation part DC bus or the common DC bus is connected to the capacity division part DC bus, and the series formation

[0100] Device or series capacity-dividing device can work.

[0101] When the DC switches in the formation main control box and the capacity division main control box are closed, the common DC bus and the capacity division DC bus

[0102] The common DC bus and the DC bus of the forming part are connected as one, and the series forming equipment and the series capacity dividing equipment can work.

[0103] In a specific embodiment, the bidirectional power conversion circuit in the series capacity division device is connected to the DC bus of the capacity division part and the series

[0104] The controlled battery part performs a capacity division process on the batteries connected in series, including multiple charging and discharging; the bidirectional power conversion circuit in the series formation equipment is connected to the DC bus of the formation part and the series controlled battery part, and performs a formation process on the batteries connected in series, including multiple charging.

[0105] Specifically, the bidirectional power conversion circuit (including bidirectional DCDC module) in the series capacity division device is connected to the DC bus of the capacity division line and the capacity division master control box; the bidirectional power conversion circuit (including bidirectional DCDC module) in the series formation device is connected to the formation line

[0106] The DC bus and the formation control box; the bidirectional power conversion circuit (including the bidirectional DCDC module) are all connected to the series circuit of the formation or capacity-dividing battery.

[0107] The series formation equipment and series capacity division equipment mainly include the power supply part and the needle bed part. This system mainly displays the power conversion. The power conversion part of the series formation equipment and series capacity division equipment mainly includes a bidirectional power conversion circuit (including a bidirectional DCDC module), a series control circuit and a battery pack. The bidirectional DCDC module is used to connect the DC bus and the series controlled battery pack.

[0108] Among them, the bidirectional power conversion circuit (including bidirectional DCDC module) in the series capacity division device connects the DC bus of the capacity division line, the capacity division master control box and the battery pack controlled in series, and the bidirectional power conversion circuit (including bidirectional DCDC module) in the series formation device connects the DC bus of the formation line, the formation master control box and the battery pack controlled in series.

[0109] In one specific embodiment, a series battery includes N cells undergoing formation and capacity separation. The N cells are connected in a series circuit by internal control of the formation and capacity separation equipment, where N is an integer greater than or equal to 8 and less than or equal to 256 ([8, 256]). The cells in the series battery are those that require charging and discharging during the formation and capacity separation processes.

[0110] In a specific embodiment, when the series capacity division equipment and the series formation equipment in the capacity division production line perform capacity division and formation respectively, the equipment performs charging and discharging operations, wherein the equipment performing the discharge operation feeds back electric energy to the common DC bus, i.e., the feedback electric energy of the DC bus, and the equipment performing the charging operation obtains electric energy from the common DC bus, i.e., the consumed electric energy of the DC bus. The electric energy flowing through the PCS equipment in the system is the difference electric energy between the feedback electric energy of the DC bus and the consumed electric energy of the DC bus. The PCS working state is automatically adjusted according to the difference electric energy between the feedback electric energy and the consumed electric energy of the DC bus. The PCS working state includes rectification state,

[0111] Inverter state, idle state and no-load state.

[0112] In one specific embodiment, when the power consumed on the common DC bus exceeds the recirculated power, the remaining power is drawn from the AC grid via the common DC bus through the PCS equipment, and the PCS operates in a rectification state. When the power consumed on the common DC bus is less than the recirculated power, the remaining power is recirculated back to the AC grid via the PCS equipment via the common DC bus, and the PCS operates in an inversion state. When the power consumed on the common DC bus equals the recirculated power, no power flows between the common DC bus and the PCS equipment, and the PCS operates in an idle state. When all series-connected forming devices and series-connected capacity-splitting devices on the common DC bus are not charging or discharging, or when the DC switches of the forming and capacity-splitting master control boxes are disconnected, the PCS operates in a no-load state.

[0113] Specifically, when the total power demand (power consumption) of the charging equipment on the public DC bus is greater than the total power (feedback power) fed back to the public DC bus by the discharging equipment, or all the equipment are in the charging state, the difference in power is transferred through the public DC bus.

[0114] The PCS equipment takes power from the AC grid and the PCS works in the rectification state.

[0115] When the electric energy consumed is less than the total electric energy fed back to the public DC bus by the discharge equipment (feedback energy), the difference in electric energy is fed back to the public DC bus.

[0116] The DC bus feeds back electric energy to the AC grid through the PCS device, and the PCS works in the inverter state; when the total electric energy (power consumption) of the charging equipment in the public DC bus is equal to the total electric energy (feedback energy) fed back to the public DC bus by the discharging equipment, the charging and discharging in the system reaches a balanced state, and there is no electric energy flowing between the public DC bus and the PCS. At this time, the PCS works in the idle state; when all the formation equipment or capacity division equipment are in sleep or not charging or discharging, or the formation control box and the distribution equipment are in a state of equilibrium, the system will be in an idle state.

[0117] When the DC switches of the main capacity control box are all disconnected, that is, when all series forming devices and series capacity dividing devices on the public DC bus are not performing charging or discharging operations, the PCS working state is no-load state.

[0118] Compared with the prior art, the energy-saving principle of the serial volume production and detection system of the present invention is:

[0119] 1. PCS working state is rectification state (including first rectification state and second rectification state)

[0120] 1. When the total power consumed by all devices in the system's common DC bus (Pcharge) when the battery is charging is greater than the total power fed back to the DC bus by all devices in the battery's discharging state (Pdischarge), that is, Pcharge > Pdischarge, the difference between Pcharge and Pdischarge (Ppcs) flowing through the PCS is obtained from the AC grid via the common DC bus and the PCS. The PCS operates in the first rectification state.

[0121] The specific energy exchange in the first rectification state is shown in Figure 8. In this state, Pcharge = Pdischarge + Ppcs (Ppcs is the energy drawn from the AC grid by the PCS). Energy fed back from the system's batteries is fed via the common DC bus to the rechargeable batteries in the system, bypassing the PCS before being fed back to the plant's AC grid for reuse. This energy feedback eliminates two conversions compared to conventional series-connected devices, reducing energy consumption by over 10%.

[0122] Meanwhile, the power passing through the PCS is only a portion of the total power. This portion, supplied by the AC grid, is more concentrated than a standalone ACDC, resulting in better operating conditions, higher efficiency, and improved grid quality. The 10% reduction in energy consumption is an approximate figure, primarily due to the reduction of two ACDC conversions in the battery power feedback path (calculated using a conventional capacity-composition device with 95% ACDC efficiency as an example). 0.95 * 0.95 = 0.9025, meaning the energy consumption of the battery power conversion process from discharge to charge is reduced by over 10% in the system.

[0123] The electricity consumed by this system from the grid via PCS is mainly the loss in the system and the energy required for battery charging. The losses mainly include cable loss, power circuit loss in the component equipment, fan power supply loss, equipment power supply loss, etc.

[0124] 2. When all devices in the system are charging, the PCS works in the second rectification state.

[0125] The specific power exchange in the second rectification state is shown in Figure 9. At this time, Ppcs = Pcharge 1 + Pcharge 2. At this time, the total power of PCS is relatively large.

[0126] All electrical energy is supplied by the AC grid through the PCS, which is conducive to the PCS operating at higher power, high overall efficiency and high grid quality.

[0127] 2. PCS working state is inverter state

[0128] When the total power consumption (Pcharging) of all devices in the battery charging state on the system's common DC bus is less than the total feedback power (Pdischarging) fed back to the DC bus by all devices in the battery discharging state, the difference in power is transferred through the common DC bus via the PCS.

[0129] To feed back electrical energy to the AC grid, the PCS operates in inverter mode.

[0130] Figure 10 illustrates the specific energy conversion in the inverter state. At this point, Pcharge + Ppcs = Pdischarge. A portion of the energy fed back from the system's batteries, Pcharge, is fed to the system's rechargeable batteries via the common DC bus, bypassing the PCS and feeding back into the plant's AC grid. This energy eliminates two ACDC conversions compared to conventional series-connected systems, reducing charge and discharge energy consumption by over 10%. Ppcs represents excess energy in the production line equipment, which is fed back to the AC grid via the common DC bus and the PCS. This improves overall production line efficiency compared to conventional solutions.

[0131] 3. PCS working status is idle

[0132] When the total electrical energy of the charging devices in the common DC bus is equal to the total electrical energy fed back to the common DC bus by the discharging devices, the charging and discharging in the system reaches a balanced state, and no electrical energy flows between the common DC bus and the PCS. At this time, the PCS working state is equivalent to the idle state.

[0133] The specific energy conversion in the equilibrium state is shown in Figure 11. At this time, P charge = P discharge, and Ppcs = 0. The discharge energy and charging energy on the common DC bus are balanced. The battery discharge cycle reduces 2 conversions compared to conventional series devices, and energy consumption is reduced by 10%.

[0134] The above improves system efficiency.

[0135] In the embodiment of the present invention, all series-connected formation devices and all series-connected capacity-splitting devices draw power from a common DC bus. The series-connected formation devices and series-connected capacity-splitting devices operate according to a predetermined formation or capacity-splitting process. Generally, series-connected formation devices operate in a charging mode, while series-connected capacity-splitting devices operate in both a charging and a discharging mode.

[0136] For example, a certain formation process generally includes: rest for 3 minutes, charge 1, rest for 3 minutes, charge 2, rest for 3 minutes, charge 3..., among which the set working currents of charge 1, charge 2, charge 3... are different, and the working time of each section is also different. A certain capacity division process is generally: rest for 5 minutes, charge 1, rest for 5 minutes, discharge 2, rest for 5 minutes, charge 3, rest for 5 minutes... On the automated production line, all equipment performs charging and discharging work at certain time intervals (mainly the logistics time of the battery entering and leaving the equipment). There is a certain time difference, and different equipment works at different charging and discharging currents at the same time, that is, some equipment is charging (with different power), some equipment is discharging (each equipment is different), and some equipment is in sleep or stopped working, etc. The charging equipment draws power from the public DC bus, and the discharging equipment converts the battery's electrical energy into electricity.

[0137] Feedback is sent to the common DC bus. The PCS automatically switches between rectification and inversion modes based on the differential energy on the common bus. Rectification draws the differential energy from the AC grid, while inversion feeds the differential energy on the common DC bus back to the AC grid. The specific energy modes of the system are as described above.

[0138] The three working conditions of PCS depend on the combined working conditions of all equipment on the production line, and each equipment works according to the process set by chemical composition and capacity.

[0139] In actual application, there will be a common DC bus with only the capacity division or formation equipment as shown in Figure 12. At this time, the capacity division equipment has charging and discharging conditions, and the overall operation mode is assimilated to the capacity division common DC bus; while the formation equipment common DC bus,

[0140] Since all processes generally only have charging mode, the main advantage of PCS is that it operates under better working conditions in most cases, with higher charging and discharging efficiency, avoiding the disadvantage of low system efficiency when a single device operates under low current conditions.

[0141] When used only in the formation department, all equipment is connected in series with the formation and testing equipment to form a common bus system for the formation department. Furthermore, multiple equipment can share only one PCS to form a small common bus system, as shown in Figure 13.

[0142] When used only for capacity distribution, all devices are connected in series as capacity distribution detection devices, forming a capacity distribution common bus system. Furthermore, multiple devices can share only one PCS to form a common bus subsystem, as shown in Figure 14.

[0143] When used only for capacity distribution, that is, all devices are connected in series as capacity distribution detection devices, another capacity distribution common busbar system can be formed. Furthermore, multiple devices use two sets of PCS, as shown in Figure 15.

[0144] This invention separates the bidirectional ACDC function and module in the conventional serial-connected component equipment. The entire production line shares a set of PCS. Each independent serial-connected component equipment is connected to a common DC bus (voltage of about 200~1500V, adjustable).

[0145] Connected to the PCS. As a result, the system's charge and discharge efficiency improves on the high charge and discharge efficiency of the original series-connected capacity-composition equipment, reducing battery cycle charge and discharge losses and improving the overall efficiency of the production line. At the same time, the PCS operates at a relatively optimal power level, with high charge and discharge efficiency and high power quality.

[0146] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Therefore, any modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A DC bus-based series capacity production and detection system, characterized in that: include: AC power grid, PCS equipment, public DC bus, capacity division DC bus, forming part DC bus, forming main control box, capacity division main control box, capacity division equipment connected in series of capacity division lines, and forming equipment connected in series of forming lines; the PCS equipment is respectively connected to the AC power grid and the public DC bus, the public DC bus is respectively connected to the forming main control box and the capacity division main control box, the capacity division equipment connected in series of capacity division lines are respectively connected to the capacity division main control box and the capacity division DC bus, the forming equipment connected in series of forming lines are respectively connected to the forming main control box and the forming part DC bus; wherein, The PCS device is a bidirectional power conversion unit used to rectify three-phase AC power into DC power or invert DC power into three-phase AC power; The formation master control box is used to control the connection between the formation unit DC bus and the public DC bus; The sub-capacity master control box is used to control the connection between the sub-capacity DC bus and the common DC bus; The series capacity separation equipment of the capacity separation line is a device used for lithium battery capacity separation in the production line, and the series formation equipment of the formation line is a device used for lithium battery formation in the production line; The series capacity division equipment and the series formation equipment are a complete set of automated intelligent production and testing devices, both including a bidirectional power conversion circuit, a needle bed and a control system, and are used for series connection of lithium batteries for capacity division; The PCS device is a bidirectional power conversion unit, including one PCS unit or multiple PCS units working in parallel. The PCS unit includes a three-phase power frequency transformer, a bidirectional ACDC converter, a DC switch, a control and indication part, The primary side of the three-phase power frequency transformer is connected to the AC power grid, and the secondary side is connected to the bidirectional ACDC converter, which performs isolation and voltage step-up and step-down functions. The primary side voltage range is 200V~35000V, and the secondary side voltage is 200V~1000V. The bidirectional ACDC converter is non-isolated and connected to a DC switch, which is connected to the common DC bus.

2. The DC bus-based series capacity production and detection system according to claim 1, characterized in that: include: The capacity division master control box includes a DC switch, a switch monitoring module, and a switch status display unit. The DC switch is used to control the connection between the common DC bus and the capacity division DC bus. The capacity division master control box controls the connection between the capacity division DC bus and the common DC bus through the DC switch. The capacity division master control box is used for power supply control and indication of the capacity division DC bus and the series capacity division equipment. The formation master control box includes a DC switch, a switch monitoring module, and a switch status display unit, wherein the DC switch is used to control the connection between the common DC bus and the formation DC bus. The formation master control box controls the connection between the formation unit DC bus and the common DC bus through the DC switch. The formation master control box is used to control and indicate the power supply to the formation unit DC bus and the series formation equipment.

3. The DC bus-based series capacity production and detection system according to claim 2, characterized in that: include: When only one of the DC switches of the formation master control box or the capacity division master control box is closed, the common DC bus is connected to the DC bus of the formation part or the common DC bus is connected to the DC bus of the capacity division part, and the series formation equipment or the series capacity division equipment is connected. Prepare to carry out work; When the DC switches in the formation master control box and the capacity division master control box are closed, the common DC bus is connected to the capacity division DC bus as a whole, and the common DC bus is connected to the formation DC bus as a whole, and the series formation equipment and the series capacity division equipment work.

4. The DC bus-based series capacity production and detection system according to claim 1, characterized in that: include: The bidirectional power conversion circuit in the series capacity division device is connected to the DC bus of the capacity division part and the battery part controlled in series, and performs a capacity division process on the series-connected batteries, including multiple charging and discharging; The bidirectional power conversion circuit in the series formation equipment is connected to the DC bus of the formation part and the battery part controlled in series, and performs a formation process on the series batteries, including multiple charging.

5. The DC bus-based series capacity production and detection system according to claim 4, characterized in that: include: The series-connected battery includes N batteries that undergo formation and capacity division, and the N batteries are controlled internally by the formation and capacity division equipment to form a series circuit, where N is an integer greater than or equal to 8 and less than or equal to 256; The battery in the series battery refers to the battery that needs to be charged and discharged during the formation process and the capacity separation process.

6. The DC bus-based series capacity production and detection system according to claim 1, characterized in that: When the series capacity division equipment and the series formation equipment in the capacity division production line perform capacity division and formation respectively, the equipment performs charging and discharging operations. Among them, the equipment performing the discharge operation feeds back electric energy to the common DC bus, that is, the feedback electric energy of the DC bus, and the equipment performing the charging operation obtains electric energy from the common DC bus, that is, the electric energy consumed by the DC bus. The electric energy flowing through the PCS equipment in the system is the difference between the feedback electric energy of the DC bus and the electric energy consumed by the DC bus. The PCS working state is automatically adjusted according to the difference between the feedback electric energy of the DC bus and the electric energy consumed by the DC bus. The PCS working state includes rectification state, inversion state, idle state and no-load state.

7. The DC bus-based series capacity production and detection system according to claim 6, characterized in that: include: When the power consumed on the public DC bus is greater than the feedback power, the difference is taken from the AC grid via the public DC bus through the PCS device, and the PCS is in the rectification state. When the power consumed on the public DC bus is less than the fed-back power, the difference is fed back to the AC grid via the public DC bus through the PCS device, and the PCS is in the inverter state. When the consumed electric energy on the common DC bus is equal to the fed-back electric energy, no electric energy flows between the common DC bus and the PCS equipment, and the PCS working state is an idle state; When all the series forming devices and series capacity dividing devices on the common DC bus are not performing charging or discharging operations, the PCS operating state is a no-load state.

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