A DC bus-based series-connected capacity production and detection system

Abstract

The invention discloses a series-connected capacity-dividing production and detection system based on a common bus, including: an AC power grid, a PCS device, a common DC bus, a capacity-dividing DC bus, a forming DC bus, a forming master control box, a capacity-dividing master control box, a series-connected capacity-dividing device of a capacity-dividing line, and a series-connected forming device of a forming line; the PCS device is respectively connected to the AC power grid and the common DC bus, the common DC bus is respectively connected to the forming master control box and the capacity-dividing master control box, the series-connected capacity-dividing device of the capacity-dividing line is respectively connected to the capacity-dividing master control box and the capacity-dividing DC bus, and the series-connected forming device of the forming line is respectively connected to the forming master control box and the DC bus of the forming part. The present invention adopts a set of PCS shared by the whole production line, and each independent device is directly collected to the common DC bus. When working, the battery feedback electric energy of the capacity-dividing is preferentially used by other capacity-dividing devices of the common bus, reducing the number of electric energy conversions of cyclic charging and discharging, improving power efficiency, and reducing electric energy loss.

Description

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 direct current bus. Background Art

[0002] The formation and capacity division process is the core process of the later stage of lithium battery. There are multiple charge and discharge processes in the formation and capacity division process, which consumes a lot of electric energy. The series formation and capacity division technology is a new detection technology developed in recent years. The series formation and capacity division technology connects dozens or hundreds of batteries in series and then charges and discharges them. It has the characteristics of high charge and discharge efficiency and good current consistency.

[0003] The bidirectional power conversion part of the series-type capacity-dividing technology is mainly divided into a bidirectional ACDC module and a bidirectional DCDC module. Among them, ACDC is used to rectify / invert the AC 380V into DC (generally between 600V and 800V, which can be set), and DCDC realizes high-precision constant current control to charge and discharge the series-type batteries. In the actual application process, there are many formation and capacity-dividing equipment on the production line. At the same time, some equipment is charging the series-type capacity-dividing battery group, and some equipment is discharging the series-type capacity-dividing battery group. These equipment are connected through 380V cables in the factory and used as the collection point (AC bus) for power conversion. When the formation equipment or capacity-dividing equipment is charged, the power is taken from the 380V AC bus and then charged and discharged to the series-type battery group through the ACDC and DCDC in the equipment; when discharging, the energy of the battery group is sent to the 380V AC bus through the DCDC and then the ACDC inverter.

[0004] The applicant has found through research that in the existing production line's capacity-combining production and testing system, all battery charge and discharge paths include ACDC-DCDC, which increases the number of feedback power conversions when the battery discharges on the production line and reduces system efficiency. At the same time, in the existing series capacity-combining technology, when the charge and discharge current is small, the total power of a single device is small and the overall conversion efficiency of the device is low. Summary of the invention

[0005] 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 a series capacity production detection system based on a DC bus.

[0006] In order to solve the above problems, the present invention is implemented according to the following technical solutions:

[0007] In a first aspect, the present invention provides a series-connected capacity production and detection system based on a DC bus, comprising:

[0008] AC power grid, PCS equipment, common DC bus, DC bus of capacity division part, DC bus of formation part, formation master control box, capacity division master control box, series capacity division equipment of capacity division line and series formation equipment of formation line; the PCS equipment is respectively connected to the AC power grid and the common DC bus, the common DC bus is respectively connected to the formation master control box and the capacity division master control box, the series capacity division equipment of capacity division line is respectively connected to the capacity division master control box and the DC bus of capacity division part, the series formation equipment of formation line is respectively connected to the formation master control box and the DC bus of formation part; wherein,

[0009] The PCS device is a bidirectional power conversion unit for rectifying three-phase AC power into DC power or inverting DC power into three-phase AC power;

[0010] The formation master control box is used to control the connection between the formation unit DC bus and the common DC bus;

[0011] The capacity division master control box is used to control the connection between the capacity division DC bus and the common DC bus;

[0012] The series capacity division equipment of the capacity division line is a device used for lithium battery capacity division 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;

[0013] The series capacity division equipment and the 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 series connection of lithium batteries for capacity division.

[0014] 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 the role of isolation and buck-boost. The primary voltage range is 200V to 35000V, and the secondary voltage is 200V to 1000V. The bidirectional ACDC converter is a non-isolated type, and the bidirectional ACDC converter is connected to the DC switch, and the DC switch is connected to the common DC bus.

[0015] 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 more than one bidirectional ACDC converter module, a DC switch, a control and indication part, the bidirectional ACDC converter module is a high-frequency isolation type, with multiple parallel outputs, the parallel input end of the bidirectional ACDC converter module is connected to the AC power grid, and the parallel output end is connected to the DC switch, and the DC switch is connected to the common DC bus.

[0016] 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, a control and indication part, and 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 to play the role of isolation and buck-boost. The primary voltage range is 200V to 35000V, and the secondary voltage is 200V to 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.

[0017] Preferably, the capacity division 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 capacity division DC bus, and the capacity division master control box controls the connection between the capacity division DC bus and the common DC bus through the DC switch, and 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;

[0018] 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 for power supply control and indication of the formation unit DC bus and series formation equipment.

[0019] Preferably, 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 can work.

[0020] 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 and the common DC bus is connected to the formation DC bus, and the series formation equipment and the series capacity division equipment can work.

[0021] 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 the capacity division process of the series-connected batteries includes multiple charging and discharging;

[0022] 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 the formation process is performed on the batteries in series, including multiple charging.

[0023] Preferably, the series-connected batteries include N batteries that are formed and divided into different capacities, and the N batteries are controlled internally by a formation and division device to form a series circuit, where N is an integer greater than or equal to 8 and less than or equal to 256;

[0024] The battery in the series-connected battery refers to the battery that needs to be charged and discharged during the formation process and the capacity division process.

[0025] Preferably, 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 electric energy consumed by the DC bus, and 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 electric energy consumed by the DC bus, and the PCS working state is automatically adjusted according to the difference electric energy between the feedback electric energy of the DC bus and the electric energy consumed by the DC bus, and the PCS working state includes rectification state, inversion state, idle state and no-load state.

[0026] Preferably, when the power consumption on the common DC bus is greater than the feedback power, the difference power is taken from the AC power grid via the common DC bus through the PCS device, and the working state of the PCS is the rectification state;

[0027] When the power consumption on the public DC bus is less than the feedback power, the difference power is fed back to the AC grid via the public DC bus through the PCS device, and the PCS working state is the inverter state;

[0028] When the power consumption on the common DC bus is equal to the feedback power, there is no power flow between the common DC bus and the PCS device, and the PCS working state is an idle state;

[0029] When all the series formation devices and series capacity division devices on the common DC bus are not performing charging and discharging operations, the PCS working state is a no-load state.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention separates the ACDC part (380V to 700V) of the dual power conversion part in the conventional capacity-splitting equipment, and the entire production line adopts a set of PCS. The AC power grid connected to the new PCS system can be a 380V low-voltage power grid to a 35kV high-voltage power grid, and the new series capacity-splitting equipment is connected to a public DC bus (voltage is about 200 to 1500V, which can be set). As a result, the architecture of the production line is transformed from the original AC bus to the public DC bus. On the basis of the high charging and discharging efficiency of the original series equipment, the overall charging and discharging efficiency of the capacity-splitting production line is reduced on the basis of the high charging and discharging efficiency of the original series equipment, and the conversion path of the feedback electric energy through the ACDC-AC bus-ACDC is reduced, the electric energy conversion is reduced, and the cycle charging and discharging efficiency is significantly improved; the PCS of the public DC bus works at a relatively good load level, with high charging and discharging efficiency, which improves the power quality of the AC power grid in the factory. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings, wherein:

[0032] Figure 1 This is a structural example diagram of a DC bus-based series-connected capacity production and detection system according to an embodiment of the present invention;

[0033] Figure 2 is a series topology diagram of a common DC bus and a series-connected capacity-sharing device according to an embodiment of the present invention;

[0034] Figure 3 It is a schematic diagram of the battery charging to discharging energy path of the DC bus-based series-connected capacity production and detection system according to an embodiment of the present invention and a conventional series-connected capacity production and detection system;

[0035] Figure 4 This is a schematic diagram showing the principle of electric energy conversion in a production and detection system based on the serial connection of a DC bus in an embodiment of the present invention;

[0036] Figure 5 is a diagram showing a first structural example of a PCS device according to an embodiment of the present invention;

[0037] Figure 6 is a diagram showing a second structural example of a PCS device according to an embodiment of the present invention;

[0038] Figure 7 is a diagram showing a third structural example of a PCS device according to an embodiment of the present invention;

[0039] Figure 8 is a schematic diagram of the principle of power conversion in a system in a first rectification state according to an embodiment of the present invention;

[0040] Fig. 9is a schematic diagram of the principle of power conversion in a system in a second rectification state according to an embodiment of the present invention;

[0041] Fig.10 is a schematic diagram of the principle of power conversion in a system in an inverter state according to an embodiment of the present invention;

[0042] Fig.11 is a schematic diagram of the principle of power conversion in a system in an idle state according to an embodiment of the present invention;

[0043] Fig.12 This is a structural example diagram of another DC bus-based series-connected capacity production and detection system according to an embodiment of the present invention;

[0044] Fig.13 2 is a structural example diagram of a series formation production detection system based on a DC bus according to an embodiment of the present invention;

[0045] Fig.14 2 is a structural example diagram of a series capacity division production detection system based on a DC bus according to an embodiment of the present invention;

[0046] Fig.15 It is a structural example diagram of another series capacity division production detection system based on a DC bus according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention are described below in conjunction with 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.

[0048] With the development of future technology, various electronic products and new energy vehicles are widely used in people's daily life. Especially in recent years, with the rapid development of new energy vehicles and new electrochemical energy storage, the demand for power batteries and energy storage batteries has grown rapidly.

[0049] The formation and capacity division process is the core process of the later stage of lithium battery. There are multiple charging and discharging processes in the formation and capacity division process, which consumes a lot of electric energy. Simply put, formation is used to activate the battery, and capacity division is used to grade and classify the battery. The series capacity division technology is a new technology developed in recent years. The series capacity division technology connects dozens or hundreds of batteries in series for charging and discharging, and has the characteristics of high charging and discharging efficiency and good current consistency.

[0050] The power conversion part of the series-connected capacity-sharing technology mainly includes bidirectional ACDC and bidirectional DCDC. Among them, the bidirectional ACDC is used to rectify the AC 380V into DC (generally between 600V and 800V, which can be set) or to invert DC into 380V AC. The bidirectional DCDC realizes high-precision constant current control to charge or discharge the series-connected batteries. When the battery is charged, it obtains the required power from the 380V power grid through ACDC and DCDC. When discharging, the battery power is fed back to the 380V grid through ACDC and DCDC for use by other electrical equipment. Compared with the parallel (5V) capacity-sharing technology, the series capacity-sharing technology has the advantages of high charging and discharging efficiency.

[0051] In actual application, there are many devices in the formation and capacity division processes in the automated production line of lithium batteries. At the same time, some formation equipment and capacity division equipment will be charging the battery (referred to as charging equipment for short), some formation equipment or capacity division 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).

[0052] These charging and discharging devices are connected through 380V cables in the factory and the collection point for power conversion is 380V AC bus. Therefore, it can be considered that conventional formation equipment and capacity division equipment share the same AC bus. All devices charging or discharging batteries need to pass through the bidirectional ACDC and the subsequent bidirectional DCDC to form a bidirectional conversion part. In this system, the energy path of battery discharge is discharge device 1 (battery pack 1--DCDC--ACDC)--380V bus--charging device 2 (ACDC--DCDC--battery pack 2). There are 2 DCDC conversion losses and 2 ACDC conversion losses between battery packs.

[0053] In order to further reduce the energy consumption of the formation and capacity division processes, and to further improve the charging and discharging efficiency of the formation and capacity division production line on the basis of the existing high efficiency of series formation and capacity division charging and discharging, the present invention has developed a series formation and capacity division production detection system based on a DC bus.

[0054] When all devices are working, they are charged and discharged by ACDC, and then DCDC is used to charge and discharge the series battery pack. For lithium battery capacity-dividing equipment, the most critical part is the high-precision constant current and constant voltage control of DCDC, which is also indispensable. The ACDC part is separated from the conventional capacity-dividing equipment, and replaced by a set of high-power ACDC, namely the public PCS, to realize the ACDC function, and form a system with the new common bus formation equipment and capacity-dividing equipment. Under the new system, the energy path of battery discharge is discharge device 1 (battery pack 1--DCDC)--DC bus--charging device 2 (DCDC--battery pack 2), and the difference in electric energy is discharged through PCS, thereby reducing the ACDC conversion loss twice from battery pack to battery pack. In this way, it is beneficial to improve the system power conversion efficiency of the formation production line and the capacity-dividing production line, and at the same time, it can reduce the use of bus cables. And with this system architecture, PCS can work at a better power level, which is beneficial to improve the system stability and AC power quality.

[0055] By adopting this solution, the system efficiency of the existing chemical component equipment can be further improved. This solution is not only applicable to the series chemical component system, but also to the parallel chemical component system.

[0056] like Figure 1 As shown, a series-connected capacity production and detection system based on a DC bus includes:

[0057] AC power grid, PCS equipment, public DC bus, DC bus of capacity division unit, DC bus of formation unit, formation master control box, capacity division master control box, series capacity division equipment of capacity division lines and series formation equipment of formation lines; PCS equipment is connected to AC power grid and public DC bus respectively, public DC bus is connected to formation master control box and capacity division master control box respectively, series capacity division equipment of capacity division lines is connected to capacity division master control box and DC bus of capacity division respectively, series formation equipment of formation lines is connected to formation master control box and DC bus of formation unit respectively; wherein,

[0058] 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;

[0059] The formation master control box is used to control the connection between the formation unit DC bus and the public DC bus;

[0060] The capacity division master control box is used to control the connection between the capacity division DC bus and the common DC bus;

[0061] The series capacity separation equipment of the capacity separation line is the equipment used for lithium battery capacity separation in the production line, and the series formation equipment of the formation line is the equipment used for lithium battery formation in the production line;

[0062] 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-connected lithium batteries.

[0063] The series capacity division equipment and series formation equipment in this system are a complete set of independent testing equipment, including power supply part, needle bed part and battery series control, etc. The specific series power topology diagram is as follows Figure 2 The power supply part mainly includes a bidirectional DCDC module, which is used to form or divide the capacity of lithium batteries (tray loading).

[0064] Furthermore, a schematic diagram of a battery discharge to charge energy path of a series-connected capacity production detection system based on a DC bus of the present invention and a conventional series-connected capacity production detection system is shown in FIG. Figure 3 As shown, the left side is a schematic diagram of the battery discharge to charge energy path of a conventional series-connected formation production and detection system, and the right side is a schematic diagram of the battery discharge to charge energy path of a series-connected formation production and detection system based on a DC bus of the present invention.

[0065] Among them, PCS equipment is a bidirectional power conversion unit that performs AC / DC conversion and connects the three-phase AC power grid and the public DC bus. PCS equipment is generally composed of power frequency isolation transformer, bidirectional ACDC converter, AC / DC switch, control and indication parts, etc. It automatically works in rectification or inversion according to the power situation on the public DC bus, and realizes the control of power factor, voltage harmonics, current harmonics, etc. to ensure the power quality of the three-phase AC power grid.

[0066] In the series-connected capacity production and detection system of the present invention, the output of the PCS is a common DC bus. The specific power change principle of this system is as follows: Figure 4 shown.

[0067] In a 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 a three-phase power frequency transformer, a bidirectional ACDC converter, a DC switch, a control and indication part, such as Figure 5 As shown, 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 the role of isolation and voltage step-up and step-down. The primary voltage range is 200V~35000V (generally 380V / 10kV), 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.

[0068] 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 more than one bidirectional ACDC converter module, a DC switch, a control and indication part, such as Figure 6 As shown, the bidirectional ACDC converter module is of high-frequency isolation type, with multiple parallel outputs. The parallel input end of the bidirectional ACDC converter module is connected to the AC power grid, the parallel output end is connected to the DC switch, and the DC switch is connected to the common DC bus.

[0069] 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 an industrial frequency transformer, multiple bidirectional ACDC converter modules, a DC switch, a control and indication part, such as Figure 7 As shown, multiple bidirectional ACDC converter modules work in parallel, the primary side of the power 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 to play 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 module is a high-frequency isolation type. The parallel output end of the bidirectional ACDC converter module is connected to a DC switch, and the DC switch is connected to a common DC bus.

[0070] In practical applications, the PCS device is a bidirectional power conversion unit, including an industrial frequency isolation transformer, a bidirectional ACDC converter module, an AC / DC switch, and a control and indication part. The industrial frequency isolation transformer connects the three-phase AC power grid and the bidirectional ACDC converter module to play the role of isolation and step-up and step-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 is only equipped with an industrial frequency isolation transformer when step-up and step-down are required.

[0071] In a specific embodiment, the capacity division 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 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.

[0072] 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 DC bus of the formation unit and the common DC bus through the DC switch. The formation master control box is used for power supply control and indication of the DC bus of the formation unit and the series formation equipment.

[0073] Specifically, the formation master control box or the capacity division master control box is mainly used for the connection and control between the PCS and all the series formation equipment of the formation line or all the capacity division equipment of the capacity division line, and mainly includes a DC switch, a switch monitoring module, a switch status display unit, etc. When the DC switch is disconnected, all the series formation equipment of the formation line or all the capacity division equipment of the capacity division line are disconnected from the PCS; when the DC switch is closed, all the series formation equipment of the formation line or all the capacity division equipment of the capacity division line are closed to the PCS, and the public DC bus is directly connected to the DC bus of the formation line or the DC bus of the capacity division line.

[0074] In a specific embodiment, when only one of the DC switches of the formation main control box or the capacity division main 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.

[0075] When the DC switches in the formation main control box and the capacity division main control box are closed, the common DC bus is connected to the DC bus of the capacity division part and the common DC bus is connected to the DC bus of the formation part, and the series formation equipment and the series capacity division equipment can work.

[0076] 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 battery part controlled in series, and the capacity division process is performed on the series-connected batteries, including multiple charging and discharging; the bidirectional power conversion circuit in the series formation device is connected to the DC bus of the formation part and the battery part controlled in series, and the formation process is performed on the series-connected batteries, including multiple charging.

[0077] Specifically, the bidirectional power conversion circuit (including the bidirectional DCDC module) in the series capacity division device connects the DC bus of the capacity division line and the capacity division master control box; the bidirectional power conversion circuit (including the bidirectional DCDC module) in the series formation device connects the DC bus of the formation line and the formation master control box; the bidirectional power conversion circuit (including the bidirectional DCDC module) is connected to the series circuit of the formation or capacity division battery.

[0078] The series formation equipment and the series capacity division equipment mainly include a power supply part and a needle bed part. This system mainly displays power conversion. The power conversion part of the series formation equipment and the 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.

[0079] Among them, the bidirectional power conversion circuit (including bidirectional DCDC module) in the series capacity division device connects the capacity division line DC bus, 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 formation line DC bus, the formation master control box and the battery pack controlled in series.

[0080] In a specific embodiment, the series-connected battery includes N batteries that are formed and divided into different capacities, and the N batteries are controlled by the internal control of the formation and 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 ([8, 256]). The battery in the series-connected battery refers to the battery that needs to be charged and discharged in the formation process and the division process.

[0081] 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 electric energy consumed by 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 electric energy consumed by the DC bus. The PCS working state is automatically adjusted according to the difference electric energy between the feedback electric energy and the electric energy consumed by the DC bus. The PCS working state includes rectification state, inversion state, idle state and no-load state.

[0082] In a specific embodiment, when the electric energy consumed on the common DC bus is greater than the feedback electric energy, the difference electric energy is taken from the AC power grid through the common DC bus through the PCS device, and the PCS working state is a rectification state. When the electric energy consumed on the common DC bus is less than the feedback electric energy, the difference electric energy is fed back to the AC power grid through the common DC bus through the PCS device, and the PCS working state is an inverter state. When the electric energy consumed on the common DC bus is equal to the feedback electric energy, there is no electric energy flow between the common DC bus and the PCS device, and the PCS working state is an idle state. When all the series formation devices and series capacity division devices on the common DC bus are not performing charging and discharging operations or the DC switches of the formation master control box and the capacity division master control box are disconnected, the PCS working state is a no-load state.

[0083] Specifically, when the total power demand (power consumption) of the charging equipment on the common DC bus is greater than the total power (feedback power) fed back to the common DC bus by the discharging equipment or all devices are in the charging state, the difference power is drawn from the AC power grid through the common DC bus through the PCS equipment, and the PCS working state is the rectification state. When the total power demand (power consumption) of the charging equipment on the public DC bus is less than the total power (feedback power) fed back by the discharging equipment to the public DC bus, the difference power is fed back to the AC power grid through the public DC bus through the PCS equipment, and the PCS working state is the inverter state; when the total power (power consumption) of the charging equipment on the public DC bus is equal to the total power (feedback power) fed back by the discharging equipment to the public DC bus, the charging and discharging in the system reaches a balanced state, and there is no power flow between the public DC bus and the PCS. At this time, the PCS working state is equivalent to the idle state; when all formation equipment or capacity division equipment are in sleep or not charged or discharged, or the DC switches of the formation main control box and the capacity division main control box are disconnected, that is, when all series formation equipment and series capacity division equipment on the public DC bus are not performing charging and discharging work, the PCS working state is the no-load state.

[0084] Compared with the prior art, the energy-saving principle of the serial component production detection system of the present invention is:

[0085] 1. PCS working state is rectification state (including first rectification state and second rectification state)

[0086] 1. When the total power consumption of all devices in the battery charging state on the common DC bus of the system (P 充 ) is greater than the total feedback energy fed back to the DC bus by all devices under battery discharge conditions (P 放 ), that is, P 充 >P 放 , the power P flowing through the PCS 充 With P 放 The difference in electrical energy (P pcs ), the difference electric energy is taken from the AC grid via the public DC bus through the PCS, and the PCS works in the first rectification state.

[0087] The specific power exchange in the first rectification state is as follows Figure 8 As shown, at this time P 充 =P 放 +P pcs (P pcsThe electric energy fed back by the battery in the system is fed back to the rechargeable battery in the system through the public DC bus, and is no longer fed back to the factory AC grid through the PCS for use. This part of the fed back electric energy reduces the conversion by 2 times compared with conventional series equipment, and the energy consumption is reduced by more than 10%. At the same time, the electric energy passing through the PCS is only a part of it. The total power of this part powered by the AC grid is more concentrated than that of an independent single ACDC, with better operating conditions, higher efficiency and better grid quality. Among them, the 10% reduction in energy consumption is an approximate number, mainly because the battery power feedback path reduces the ACDC conversion by 2 times (calculated based on the ACDC efficiency of 95% of conventional capacity-compounding equipment), 0.95*0.95=0.9025, that is, the energy consumption of the battery discharge to charge process in the system is reduced by more than 10%.

[0088] The electricity consumed by this system from the power grid through PCS is mainly the loss in the system and the electricity required for battery charging. The losses mainly include cable loss, power circuit loss in the chemical composition equipment, fan power supply loss, equipment power supply loss, etc.

[0089] 2. When all devices in the system are charging, the PCS working state is the second rectification state.

[0090] The specific power exchange in the second rectification state is as follows Fig. 9 As shown, at this time P pcs =P 充1 +P 充2 At this time, the total power of PCS is relatively large, and all the electric energy is supplied by the AC grid through PCS, which is conducive to PCS running at a higher power, high overall efficiency and high grid quality.

[0091] 2. PCS working state is inverter state

[0092] When the total power consumption of all devices in the battery charging state on the common DC bus of the system (P 充 ) is less than the total feedback energy fed back to the DC bus by all devices under battery discharge conditions (P 放 ), the difference electric energy is fed back to the AC grid through the public DC bus through the PCS, and the PCS works in the inverter state.

[0093] The specific power conversion in the inverter state is as follows: Fig.10 As shown, at this time P 充 +P pcs =P 放 . A portion of the energy fed back by the battery in the system P 充 The rechargeable battery in the system is fed back to the factory AC grid through the public DC bus, and no longer passes through the PCS. This part of the power reduces the ACDC conversion by 2 times compared with conventional series equipment, and the energy consumption of the charge and discharge cycle is reduced by more than 10%. pcsThe excess electric energy in the production line equipment is fed back to the AC grid through the common DC bus through the PCS, so that the overall efficiency of the production line is higher than that of the conventional solution.

[0094] 3. PCS working state is idle state

[0095] When the total electrical energy of the charging equipment in the common DC bus is equal to the total electrical energy fed back to the common DC bus by the discharging equipment, the charging and discharging in the system reaches a balanced state, and there is no electrical energy flowing between the common DC bus and the PCS. At this time, the working state of the PCS is equivalent to the idle state.

[0096] The specific electrical energy transformation in the equilibrium state is as follows Fig.11 As shown, at this time P 充 =P 放 , P pcs = 0. The discharge power and charging power on the public DC bus are balanced, and the battery discharge cycle reduces 2 conversions compared to conventional series equipment, reducing energy consumption by more than 10%, thereby improving system efficiency.

[0097] In the embodiment of the present invention, all series formation devices and all series capacity division devices are powered by a common DC bus, and the series formation devices and series capacity division devices work according to the set formation or capacity division process. Generally, the series formation device works in a charging mode, and the series capacity division device has two working modes: charging mode and discharging mode.

[0098] For example, a formation process generally includes: rest for 3 minutes, charge 1, rest for 3 minutes, charge 2, rest for 3 minutes, charge 3..., where the set working currents of charge 1, charge 2, charge 3... are different, and each working time is also different. A capacity division process generally includes: 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 at certain time intervals (mainly the logistics time of the battery entering and exiting the equipment), and there is a certain time difference. 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 has differences), and some equipment is dormant or stopped working. The charging equipment takes power from the public DC bus, and the discharging equipment feeds the battery power back to the public DC bus. The PCS automatically works in rectification or inverter mode according to the difference power on the public bus. When rectifying, it takes the difference power from the AC power grid, and when inverting, it feeds the difference power on the public DC bus back to the AC power grid. The specific energy modes of the system are as described in the above four situations.

[0099] 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.

[0100] In actual application, there will be a common DC bus that is only divided or formed into independent devices, such as Fig.12 At this time, the capacity-dividing equipment has charging and discharging conditions, and the overall operation mode is assimilated into the capacity-dividing common DC bus; and the formation equipment common DC bus, because all processes generally only have charging mode, the main advantage of PCS is that it operates in better conditions in most cases, with higher charging and discharging efficiency, avoiding the disadvantage of low system efficiency when a single device is in low current condition.

[0101] When it is only used in the formation department, that is, all the equipment are connected in series with the formation test equipment, forming a common bus system of the formation department. Furthermore, if only multiple equipment share one set of PCS, a small common bus system can also be formed, such as Fig.13 shown.

[0102] When it is only used for the capacity division, that is, all devices are connected in series to form a common bus system for the capacity division. Furthermore, if multiple devices share one PCS, a small common bus system can also be formed, such as Fig.14 shown.

[0103] When it is only used for the capacity division, that is, all devices are series capacity division detection devices, another capacity division common busbar system can be formed. Furthermore, multiple devices use 2 sets of PCS, such as Fig.15 shown.

[0104] The present invention separates the bidirectional ACDC function and module in the original conventional series-connected capacity-sharing equipment. The entire production line shares a set of PCS, and each independent series-connected capacity-sharing equipment is connected to the PCS through a common DC bus (voltage of about 200 to 1500V, which can be set). As a result, the system's charge and discharge efficiency is based on the high charge and discharge efficiency of the original series-connected capacity-sharing equipment, reducing the battery cycle charge and discharge loss and improving the overall efficiency of the production line; at the same time, the PCS works at a relatively good power level, with high charge and discharge efficiency and high power quality.

[0105] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A series connection capacity production detection system based on DC bus, characterized in that: include: AC power grid, PCS equipment, common DC bus, DC bus of capacity division part, DC bus of formation part, formation master control box, capacity division master control box, series capacity division equipment of capacity division line and series formation equipment of formation line; the PCS equipment is respectively connected to the AC power grid and the common DC bus, the common DC bus is respectively connected to the formation master control box and the capacity division master control box, the series capacity division equipment of capacity division line is respectively connected to the capacity division master control box and the DC bus of capacity division part, the series formation equipment of formation line is respectively connected to the formation master control box and the DC bus of formation part; wherein, The PCS device is a bidirectional power conversion unit for rectifying three-phase AC power into DC power or inverting 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 common DC bus; The capacity division master control box is used to control the connection between the capacity division DC bus and the common DC bus; The series capacity division equipment of the capacity division line is a device used for lithium battery capacity division 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 of which include a bidirectional power conversion circuit, a needle bed and a control system, and are used for series connection of lithium batteries for capacity division; Among them, 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, 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 the role of isolation and buck-boost. The primary voltage range is 200V~35000V, and the secondary voltage is 200V~1000V. The bidirectional ACDC converter is a non-isolated type, and the bidirectional ACDC converter is connected to the DC switch, and the DC switch is connected to the common DC bus.

2. The series connection capacity production detection system based on DC bus according to claim 1 is characterized in that: include: The capacity division 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 capacity division DC bus, and the capacity division master control box controls the connection between the capacity division DC bus and the common DC bus through the DC switch, and 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 for power supply control and indication of the formation unit DC bus and series formation equipment.

3. The series connection capacity production detection system based on DC bus according to claim 2 is 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 works; 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 series connection capacity production detection system based on DC bus according to claim 1 is 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 the series battery is subjected to a capacity division process, 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 the formation process of the series batteries is carried out, including multiple charging.

5. The series connection capacity production detection system based on DC bus according to claim 4 is characterized in that: include: The series-connected battery includes N batteries that are formed and divided into different capacities, and the N batteries are controlled by the internal control of 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-connected battery refers to the battery that needs to be charged and discharged during the formation process and the capacity division process.

6. The series connection capacity production detection system based on DC bus according to claim 1 is 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, wherein the equipment performing the discharging 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 electric energy consumed by 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 electric energy consumed by the DC bus. The PCS working state is automatically adjusted according to the difference electric energy 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 series connection capacity production detection system based on DC bus according to claim 6 is characterized in that: include: When the power consumption on the public DC bus is greater than the feedback power, the difference power is taken from the AC power grid through the public DC bus through the PCS device, and the working state of the PCS is the rectification state; When the power consumption on the public DC bus is less than the feedback power, the difference power is fed back to the AC grid via the public DC bus through the PCS device, and the PCS working state is the inverter state; When the power consumption on the common DC bus is equal to the feedback power, there is no power flow between the common DC bus and the PCS device, and the PCS working state is an idle state; When all the series formation devices and series capacity division devices on the common DC bus are not performing charging and discharging operations, the PCS working state is a no-load state.

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