A lithium iron phosphate battery charging and discharging system and a control method thereof

Abstract

This invention provides a lithium iron phosphate battery charging and discharging system and its control method, including a housing and a controller. The controller includes a charging module and a discharging module. The charging module controls the charging power of the battery cell assembly, and the discharging module controls the discharging power of the battery cell assembly. Two partitions are spaced with grooves, and battery cell assemblies are arranged within the grooves. Each battery cell assembly includes a cell shell and battery cells. A heat dissipation channel is provided inside the cell shell, with a four-way valve connected to its top and a three-way valve connected to its bottom. Outlet one of the three-way valve is connected to an exhaust pipe, and outlet two is connected to a drain pipe. The exhaust pipe is connected to the outside, and the drain pipe is connected to a heat exchanger and then connected to a cavity three via a return pipe. Air cooling and liquid cooling mechanisms are respectively driven onto the inlet of the four-way valve. A temperature sensor is provided on the battery cell assembly. This invention can prioritize heat dissipation for individual battery cell assemblies, optimize the overall heat dissipation power of the liquid cooling mechanism and the distribution of heat dissipation power between individual battery cell assemblies, eliminate the bottleneck effect, and improve the overall charging and discharging power of the battery.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery charging and discharging, in particular to a lithium iron phosphate battery charging and discharging system and a control method thereof. BACKGROUND

[0002] Lithium iron phosphate battery (LiFePO4), also known as LFP battery, is an important component in electric vehicles and large-scale energy storage systems. In electric vehicles, lithium iron phosphate battery as the core power battery, the lithium iron phosphate battery charging and discharging system mainly consists of battery pack, battery management system (BMS), charging device and discharging device. The working principle of the system is based on the embedding and de-embedding of lithium ions. In the charging process, lithium ions are de-embedded from the positive material lithium iron phosphate, move to the negative electrode through the electrolyte and embed therein. The discharging process is the opposite, lithium ions are released from the negative electrode and move to the positive electrode again, and release electric energy at the same time.

[0003] The battery charging and discharging system is mainly divided into charging system, discharging system and charging and discharging power control system according to its function and application scene. The charging system is responsible for converting external electric energy into chemical energy inside the battery, and the discharging system converts the chemical energy inside the battery into external available electric energy. The charging and discharging power control system controls the charging and discharging power of the battery according to the demand of the system to meet the power requirement of the system. The control method of the lithium iron phosphate battery charging and discharging system mainly includes conventional charging, temperature control charging, equalization charging, conventional discharging, temperature control discharging and equalization discharging strategies. These strategies aim to ensure that the battery maintains high efficiency, stability and safety during charging and discharging.

[0004] In the prior art, in order to improve the voltage level, multiple cell groups are connected in series inside the lithium iron phosphate battery. However, during the charging and discharging process of the lithium iron phosphate battery, the temperature of a certain cell group often rises too fast, reaches the cell group temperature threshold first, and the bucket effect occurs, which limits the charging and discharging power of the overall battery. In addition, when a single cell group accumulates heat at a single point, it will affect the internal resistance of the battery, thereby affecting the overall battery performance. SUMMARY

[0005] Therefore, the application provides a lithium iron phosphate battery charging and discharging system, which sets a charging module and a discharging module. The charging module is used to control the charging power of the cell group, and the discharging module is used to control the discharging power of the cell group. A wind cooling mechanism and a liquid cooling mechanism are provided, which can measure the maximum charging power and the maximum discharging power according to the temperature state of the cell group. The maximum charging and discharging power mode is adopted to match the charging power and the heat dissipation power, so as to ensure that the battery temperature is stable within a safe range.

[0006] The technical scheme of the application is as follows:

[0007] A lithium iron phosphate battery charging and discharging system and its control method include a housing and a controller. The housing contains a first partition and a second partition, which divide the interior of the housing into three cavities from top to bottom: a first cavity, a second cavity, and a third cavity. The controller is located in the first cavity and includes a charging module and a discharging module. The charging module controls the charging power of the battery cell assembly, and the discharging module controls the discharging power of the battery cell assembly. The second partition has spaced grooves in which a battery cell assembly slides. The battery cell assembly includes a cell shell and battery cells. The four side walls of the cell shell have spiral heat dissipation channels. The top of each heat dissipation channel is connected to a four-way valve, and the bottom is connected to a three-way valve. The first outlet of the three-way valve is connected to an exhaust pipe, and its second outlet is connected to a drain pipe. The air duct passes through the shell and connects to the outside. The drain pipe is connected to a heat exchanger. The heat exchanger is connected to cavity three through a return pipe. A sliding sleeve is provided on the bottom surface of the shell. A sliding rod is provided inside the sliding sleeve. The top of the sliding rod is connected to the bottom surface of the battery pack. A helical spring is provided inside the sliding sleeve. A locking mechanism is provided on the side wall of the sliding groove. A driving mechanism and a calibration mechanism are provided on the bottom surface of partition one. A push plate is provided at the bottom of the driving mechanism. The push plate is located above the battery cell pack. An air cooling mechanism and a liquid cooling mechanism are provided in cavity two. The air cooling mechanism and the liquid cooling mechanism are respectively driven to the inlet of the four-way valve. The calibration mechanism can prioritize heat dissipation for the battery cell pack. Multiple temperature sensors are provided on the battery cell pack. The controller is electrically connected to the four-way valve, three-way valve one, driving mechanism, air cooling mechanism, liquid cooling mechanism, and locking mechanism.

[0008] Preferably, the air-cooling mechanism includes a fan, a main air duct, and a secondary air duct. The fan is located on the side wall of the housing, and the main air duct is located inside the cavity. One end of the main air duct is connected to the fan, and the other end extends and is located on one side of the battery cell assembly. The main air duct is connected to a four-way valve through the secondary air duct, and the outlet of the four-way valve is connected to the heat dissipation channel.

[0009] Preferably, the liquid cooling mechanism includes a main liquid pipe, a circulation pump, and a secondary liquid pipe. One end of the main liquid pipe is located at the bottom of the third cavity, and the other end extends through the second partition into the second cavity and is located on one side of the battery cell assembly. The circulation pump is located on the main liquid pipe and inside the second cavity. The main liquid pipe is connected to a four-way valve through the secondary liquid pipe.

[0010] Preferably, the driving mechanism includes a first support plate, a first lead screw, a first motor, a first moving block, and a first electric push rod. The first support plate is disposed on a bottom surface of a partition plate. One end of the first lead screw is rotatably connected to the housing, and the other end passes through the first support plate and is driven by the first motor. The first motor is disposed on the side of the first support plate. The first moving block is disposed on the first lead screw, and the first electric push rod is disposed on the bottom surface of the first moving block.

[0011] Preferably, the locking mechanism includes a second electric push rod and a locking block. The side wall of the slide groove is provided with a receiving groove. The second electric push rod is disposed in the receiving groove, and its telescopic end is connected to the side of the locking block. The locking block is slidably disposed in the receiving groove and its side abuts against the side of the battery cell assembly.

[0012] Preferably, the calibration mechanism includes a moving mechanism, a telescopic tube, a two-way valve, a connecting cover, a connecting pipe, and a flow valve. The moving mechanism is located on the bottom surface of a partition and is used to drive the connecting cover to move. One end of the telescopic tube is connected to the two-way valve and the other end is connected to the connecting cover. The two-way valve is connected to the main liquid pipe. The connecting cover has a cavity four. The flow valve is located at the bottom of the connecting cover. The connecting pipe is located at the top of the four-way valve and connected to its inlet.

[0013] Preferably, the moving mechanism includes a second support plate, a second lead screw, a second motor, a second moving block, and a third electric push rod. The second support plate is disposed on a bottom surface of a partition plate. One end of the second lead screw is rotatably connected to the housing, and the other end passes through the second support plate and is driven by the second motor. The second motor is disposed on the side of the second support plate. The second moving block is disposed on the second lead screw. The third electric push rod is disposed on the bottom surface of the second moving block. The telescopic end of the third electric push rod is provided with a push plate. The second motor is electrically connected to the controller.

[0014] Preferably, the top surface of the connecting pipe is provided with a sealing ring, the bottom of which is nested in the top of the connecting pipe, and the top of which is higher than the top surface of the connecting pipe.

[0015] Preferably, it also includes induction coils, which are respectively disposed on the bottom surface of the connecting cover and the side surface of the connecting pipe, and the controller is electrically connected to the induction coils.

[0016] A control method for a lithium iron phosphate battery charging and discharging system includes the following steps:

[0017] S01, Set the maximum operating power of the liquid cooling mechanism;

[0018] S02, Set the maximum charging temperature value of the battery pack;

[0019] S03. Start the liquid cooling mechanism and maintain it at maximum operating power;

[0020] S04. The charging module slowly increases the charging power. When the temperature sensor detects the maximum charging temperature, a larger charging power is obtained.

[0021] S05. The liquid cooling mechanism allocates a portion of the power to the battery cell assembly that experiences the highest temperature for heat dissipation.

[0022] S06. Continue to slowly increase the charging power until the temperature of each cell group is uniform and the system reaches a new temperature equilibrium state, at which point the maximum charging power is obtained.

[0023] S07. The discharge module repeats steps S01 to S06 above to obtain the maximum discharge power.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The system includes charging and discharging modules. The charging module controls the charging power of the battery cell assembly, while the discharging module controls the discharging power. It also features air cooling and liquid cooling mechanisms. The air cooling mechanism has a hot air function, which can heat the battery in low-temperature environments to improve charging efficiency. The charging and discharging system includes a calibration mechanism that prioritizes heat dissipation for individual battery cell assemblies, optimizing the overall heat dissipation power of the liquid cooling mechanism and the distribution of heat dissipation power among individual battery cell assemblies. This ensures uniform temperature distribution across the battery cell assembly, maintaining system temperature equilibrium, eliminating the "weakest link" effect, and improving the overall charging and discharging power of the battery. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only preferred embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a three-dimensional structural diagram of a lithium iron phosphate battery charging and discharging system according to the present invention;

[0028] Figure 2 This is a schematic cross-sectional view of a lithium iron phosphate battery charging and discharging system according to the present invention.

[0029] Figure 3 for Figure 2 Enlarged view of section AA;

[0030] Figure 4 for Figure 2 Enlarged view of section BB;

[0031] Figure 5 for Figure 2 Enlarged view of point C in the middle;

[0032] Figure 6 for Figure 3 Enlarged view at point D;

[0033] Figure 7 This is a schematic diagram of the battery cell assembly of the present invention;

[0034] Reference numerals: 1. Housing; 2. Partition 1; 3. Partition 2; 4. First support plate; 5. First lead screw; 6. First motor; 7. First moving block; 8. First electric actuator; 9. Fan; 10. Battery cell housing; 11. Heat dissipation channel; 12. Four-way valve; 13. Main air duct; 14. Secondary air duct; 15. Exhaust air duct; 16. Slide groove; 17. Slide rod; 18. Sleeve; 19. Helical spring; 20. Controller; 21. Temperature sensor; 22. Battery cell; 23. Cavity 1; 24. Cavity 2; 25. Cavity 3; 26. Drain pipe; 27. 1. Main liquid pipe; 28. Second motor; 29. ​​Circulating pump; 30. Secondary liquid pipe; 31. Receiving tank; 32. Second electric actuator; 33. Locking block; 34. Connecting pipe; 35. Connecting cover; 36. Cavity four; 37. Induction coil; 38. Sealing ring; 39. Flow valve; 40. Heat exchanger; 41. Return pipe; 42. Three-way valve one; 43. Telescopic pipe; 44. Charging module; 45. Discharging module; 46. Three-way valve two; 47. Push plate; 48. Second support plate; 49. Second lead screw; 50. Second moving block; 51. Third electric actuator. Detailed Implementation

[0035] To better understand the technical content of this invention, a specific embodiment is provided below, and the invention will be further described in conjunction with the accompanying drawings.

[0036] See Figures 1 to 7This invention provides a lithium iron phosphate battery charging and discharging system, including a housing 1 and a controller 20. The housing 1 has a first partition 2 and a second partition 3, which divide the interior of the housing 1 from top to bottom into a first cavity 23, a second cavity 24, and a third cavity 25. The third cavity 25 stores coolant. The controller 20 is located within the first cavity 23 and includes a charging module 44 and a discharging module 45. The charging module 44 controls the charging power of the battery cell assembly. The discharge module 45 is used to control the discharge power of the battery cell assembly. The partition 2 3 is provided with spaced grooves 16, within which the battery cell assembly slides. The battery cell assembly includes a battery cell shell 10 and battery cells 22. The battery cell shell 10 is made of a metal material with good thermal conductivity. Spiral heat dissipation channels 11 are provided in the four side walls of the battery cell shell 10. A four-way valve 12 is connected to the top of each heat dissipation channel 11, and a three-way valve 42 is connected to its bottom. An exhaust pipe 15 is connected to the outlet of the three-way valve 42. A drain pipe 26 is connected to the housing 1. The exhaust pipe 15 passes through the housing 1 and communicates with the outside. The drain pipe 26 is connected to a heat exchanger 40. The heat exchanger 40 is connected to the cavity 25 through a return pipe 41. A sliding sleeve is provided on the bottom surface of the housing 1. A sliding rod 17 is provided inside the sliding sleeve. The top of the sliding rod 17 is connected to the bottom surface of the battery pack. A helical spring 19 is provided inside the sliding sleeve. A locking mechanism is provided on the side wall of the sliding groove 16. A driving mechanism and a calibration mechanism are provided on the bottom surface of the partition 2. The bottom of the driving mechanism... A push plate 47 is provided, which is located above the battery cell assembly. The cavity 24 is equipped with an air cooling mechanism and a liquid cooling mechanism, which are respectively driven to the inlet of the four-way valve 12. The calibration mechanism can prioritize heat dissipation of the battery cell assembly. The battery cell assembly is equipped with multiple temperature sensors 21. The controller 20 is electrically connected to the four-way valve 12, the three-way valve 42, the drive mechanism, the air cooling mechanism, the liquid cooling mechanism, and the locking mechanism. The battery cell shell 10 is made of a metal material with good thermal conductivity.

[0037] When the charging and discharging system is working, the battery charging operation is set to two modes: normal charging mode and fast charging mode. When the charging module 44 is in normal charging mode, the temperature sensor 21 is first activated to monitor the temperature of the battery cell assembly. The temperature sensor 21 monitors the temperature of the battery cell assembly in real time. When the temperature is lower than the minimum value of the normal charging temperature range of the battery cell assembly, the controller 20 starts the fan 9. The fan 9 generates hot air and heats the battery cell assembly through the heat dissipation channel 11, raising the temperature of the battery cell assembly to within the normal charging temperature range, which helps to improve charging efficiency. The charging module 44 increases the charging power in stages. As the battery pack charges, it generates heat. When the temperature sensor 21 detects that the battery pack temperature is higher than the maximum value of the normal range, the charging module 44 stabilizes at this stage of power and starts the fan 9 to generate airflow that enters the heat dissipation channel 11 through the main air duct 13 and the secondary air duct 14 to cool the battery pack, thereby keeping the battery pack temperature within the normal range, which is beneficial for the charging and discharging operation of the battery pack. When the charging module 44 is in fast charging mode, the temperature sensor 21 is first activated to monitor the temperature of the battery pack. The temperature sensor 21 monitors the temperature of the battery pack in real time. When the temperature is lower than the minimum value of the normal charging temperature range of the battery pack, the controller 20 starts the fan 9. The fan 9 generates hot air that heats the battery pack through the heat dissipation channel 11, raising the temperature of the battery pack to within the normal charging temperature range. Then the air cooling mechanism is stopped, and the fan 9 is activated. The liquid cooling mechanism dissipates heat from the battery cells, using maximum power P1 to cool all battery cells. Then, the charging module 44 is activated, and the charging power is slowly increased. When the temperature sensor 21 on one of the battery cells reaches the preset maximum temperature value Tmax, the controller 20 determines that the temperature difference between Tmax and any of the remaining battery cells exceeds the threshold ΔT. At this point, the calibration mechanism is immediately activated, connecting the liquid cooling mechanism to the battery cells. The liquid cooling mechanism allocates some power to the battery cell with the highest temperature for heat dissipation, lowering the temperature of the high-temperature battery cell. The temperatures of other battery cells may rise slightly. Then, the charging module 44 is activated again, and the charging power is slowly increased. The temperature of the battery cells continues to be monitored by the temperature sensor 21 until the temperature difference between any of the battery cells is less than ΔT, and the temperatures of all battery cells are uniform. The system reaches a new temperature equilibrium state, at which point the maximum charging power is obtained. The discharging module 45 repeats the above steps to obtain the maximum discharging power. After determining the maximum charging power and maximum discharging power, the discharging module 45 and the charging module 44 control the charging and discharging power to be gradually increased to these maximum power values ​​for efficient charging and discharging operations. The charging and discharging system can prioritize heat dissipation for individual cell groups, optimize the distribution of overall heat dissipation power of the liquid cooling mechanism and heat dissipation power of individual cell groups, eliminate the weakest link effect, and improve the overall charging and discharging power of the battery.

[0038] Preferably, the air-cooling mechanism includes a fan 9, a main air duct 13, and a secondary air duct 14. The fan 9 is located on the side wall of the housing 1. The main air duct 13 is located in the cavity 24, with one end connected to the fan 9 and the other end extending and located on one side of the battery cell assembly. The main air duct 13 is connected to a four-way valve 12 through the secondary air duct 14. The outlet of the four-way valve 12 is connected to the heat dissipation channel 11.

[0039] When the charging module 44 and the discharging module 45 are working, the temperature sensor 21 monitors the temperature of the battery pack in real time. When the temperature is lower than the minimum value of the normal range, the controller 20 starts the fan 9. The fan 9 generates hot air and enters the heat dissipation channel 11 through the main air duct 13 and the secondary air duct 14 to heat up the battery pack. As the battery pack is charged or discharged, the battery pack will generate heat. When the temperature sensor 21 detects that the temperature of the battery pack is higher than the maximum value of the normal range, the fan 9 generates airflow and enters the heat dissipation channel 11 through the main air duct 13 and the secondary air duct 14 to cool down the battery pack, thereby keeping the temperature of the battery pack within the normal range, which is beneficial to the charging and discharging of the battery pack.

[0040] Preferably, the liquid cooling mechanism includes a main liquid pipe 27, a circulation pump 29, and a secondary liquid pipe 30. One end of the main liquid pipe 27 is located at the bottom of the cavity 25, and the other end extends through the partition 23 into the cavity 24 and is located on one side of the battery cell assembly. The circulation pump 29 is mounted on the main liquid pipe 27 and located inside the cavity 24. The main liquid pipe 27 is connected to the four-way valve 12 through the secondary liquid pipe 30.

[0041] When the charging module 44 and the discharging module 45 are operating at high power, the battery cell assembly will generate a large amount of heat. At this time, the air cooling mechanism can no longer meet the heat dissipation requirements, so the controller 20 starts the liquid cooling mechanism. First, the four-way valve 12 and the three-way valve 46 are started to connect the main liquid pipe 27 with the heat dissipation channel 11 and the heat dissipation channel 11 with the drain pipe 26. Then, the circulation pump 29 is started. The circulation pump 29 draws the coolant stored in the cavity 25 into the main liquid pipe 27. The coolant enters the heat dissipation channel 11 from the main liquid pipe 27 through the secondary liquid pipe 30, thereby dissipating heat from the battery cell assembly and improving the heat dissipation efficiency of the battery cell assembly.

[0042] Preferably, the driving mechanism includes a first support plate 4, a first lead screw 5, a first motor 6, a first moving block 7, and a first electric push rod 8. The first support plate 4 is disposed on the bottom surface of the partition plate 2. One end of the first lead screw 5 is rotatably connected to the housing 1, and the other end passes through the first support plate 4 and is driven by the first motor 6. The first motor 6 is disposed on the side of the first support plate 4. The first moving block 7 is disposed on the first lead screw 5, and the first electric push rod 8 is disposed on the bottom surface of the first moving block 7.

[0043] The drive mechanism is used to move the push plate 47 so that it moves directly above the battery cell assembly. When the battery cell assembly needs to be lowered, the first motor 6 is started first. The rotation of the first motor 6 drives the first lead screw 5 to rotate, thereby driving the first moving block 7 to move along the axis of the first lead screw 5. The movement of the first moving block 7 drives the first electric push rod 8 to move directly above the battery cell assembly to be lowered. Then the first electric push rod 8 is started. The extension end of the first electric push rod 8 extends, driving the push plate 47 to descend. The push plate 47 descends and abuts against the top of the battery cell assembly, thereby pushing the battery cell assembly down.

[0044] Preferably, the locking mechanism includes a second electric push rod 32 and a locking block 33. The side wall of the slide groove 16 is provided with a receiving groove 31. The second electric push rod 32 is disposed in the receiving groove 31, and its telescopic end is connected to the side of the locking block 33. The locking block 33 is slidably disposed in the receiving groove 31 and its side abuts against the side of the battery cell assembly.

[0045] The locking mechanism is used to fix the battery cell assembly in the slide groove 16. When the temperature sensor 21 detects that the battery pack temperature exceeds the preset value, the controller 20 activates the locking mechanism. First, the second electric push rod 32 is activated. The extension end of the second electric push rod 32 shortens, causing the locking block 33 to move and release the battery pack. Then, the drive mechanism is activated, which pushes the battery cell assembly downward. The bottom of the battery cell assembly enters the cavity 25 and enters the coolant. Then, the drive mechanism stops and the locking mechanism is activated at the same time to lock the battery cell assembly, thereby achieving the effect of emergency cooling.

[0046] Preferably, the calibration mechanism includes a moving mechanism, a telescopic tube 43, a two-way valve 46, a connecting cover 35, a connecting pipe 34, and a flow valve 39. The moving mechanism is located on the bottom surface of the partition 2 and is used to drive the connecting cover 35 to move. One end of the telescopic tube 43 is connected to the two-way valve 46, and the other end is connected to the connecting cover 35. The two-way valve 46 is connected to the main liquid pipe 27. The connecting cover 35 has a cavity 36 inside. The flow valve 39 is located at the bottom of the connecting cover 35 and is used to detect the coolant flow rate to determine whether there is a blockage in the coolant. The connecting pipe 34 is located at the top of the four-way valve 12 and is connected to its inlet.

[0047] When a cell pack reaches a high temperature, a calibration mechanism is used to prioritize heat dissipation for the cell pack to prevent localized overheating. When the calibration mechanism is activated, the moving mechanism first moves the connecting cover 35 to directly above the connecting pipe 34 and completes the connection. Then, the circulation pump 29 is activated, drawing coolant from the conduit. Simultaneously, the three-way valve is activated, connecting the conduit and the telescopic pipe 43. Coolant flows from the conduit into the telescopic pipe 43 and into the cavity 36, passing through the flow valve 39 and the connecting pipe into the heat dissipation channel 11. This allows the liquid cooling mechanism to allocate a portion of its power to prioritize heat dissipation for the cell pack.

[0048] Preferably, the moving mechanism includes a second support plate 48, a second lead screw 49, a second motor 28, a second moving block 50, and a third electric push rod 51. The second support plate 48 is disposed on the bottom surface of the partition 2. One end of the second lead screw 49 is rotatably connected to the housing 1, and the other end passes through the second support plate 48 and is driven by the second motor 28. The second motor 28 is disposed on the side of the second support plate 48. The second moving block 50 is disposed on the second lead screw 49. The third electric push rod 51 is disposed on the bottom surface of the second moving block 50. The telescopic end of the third electric push rod 51 is provided with a push plate 47. The second motor 28 is electrically connected to the controller 20.

[0049] The moving mechanism is used to drive the battery cell assembly to move down along the slide 16, causing the bottom of the battery cell assembly to descend and be immersed in the coolant, thereby achieving the effect of cooling. When the moving mechanism is started, the second motor 28 is started first. The rotation of the second motor 28 drives the second lead screw 49 to rotate, thereby driving the second moving block 50 to move along the axis of the second lead screw 49. The movement of the second moving block 50 drives the third electric push rod 51 to move, thereby moving the push plate 47 to be directly above the battery cell assembly to be lowered. Then, the third electric push rod 51 is started. The telescopic end of the third electric push rod 51 extends, thereby driving the push rod to descend and abut against the top of the battery cell assembly, realizing the function of lowering the battery cell assembly.

[0050] Preferably, the top surface of the connecting pipe 34 is provided with a sealing ring 38, the bottom of the sealing ring 38 is nested in the top of the connecting pipe 34, and its top is higher than the top surface of the connecting pipe 34.

[0051] The bottom of the sealing ring 38 is nested in the top of the connecting pipe 34. When the connecting cover 35 and the connecting pipe 34 are connected, the bottom surface of the connecting cover 35 abuts against the sealing ring 38. The sealing ring 38 has a certain elasticity, which can play a sealing role to prevent coolant leakage. At the same time, it also plays a buffering role to prevent the connecting cover 35 and the connecting pipe 34 from directly contacting each other.

[0052] Preferably, it also includes induction coils, which are respectively disposed on the bottom surface of the connecting cover 35 and the side surface of the connecting tube 34, and the controller 20 is electrically connected to the induction coils.

[0053] When the moving mechanism drives the connecting cover 35 and the connecting tube 34 to dock, the induction coil on the side of the connecting tube 34 is an active coil. With different numbers of turns, different magnetic flux can be generated by a preset current. The induction coil at the bottom of the connecting cover 35 is a passive coil. When the two induction coils approach each other, the passive coil will generate different currents. The parameters of the induction coils set on the top of different battery packs are different. According to the different currents generated, the controller 20 can move the connecting cover 35 to the connecting tube 34 on the top of a specific battery pack for docking. At the same time, the two induction coils will generate electromagnetic force, so that the connecting cover 35 and the connecting tube 34 are tightly connected, which helps to improve the sealing performance.

[0054] A control method for a lithium iron phosphate battery charging and discharging system includes the following steps:

[0055] S01, Set the maximum operating power of the liquid cooling mechanism;

[0056] S02, Set the maximum charging temperature value of the battery pack;

[0057] S03. Start the liquid cooling mechanism and maintain it at maximum operating power;

[0058] S04, the charging module 44 slowly increases the charging power. When the temperature sensor detects that the maximum charging temperature is reached, a larger charging power is obtained.

[0059] S05. The liquid cooling mechanism allocates a portion of the power to the battery cell assembly that experiences the highest temperature for heat dissipation.

[0060] S06. Continue to slowly increase the charging power until the temperature of each cell group is uniform and the system reaches a new temperature equilibrium state, at which point the maximum charging power is obtained.

[0061] S07. The discharge module 45 repeats steps S01 to S06 above to obtain the maximum discharge power.

[0062] Set the maximum power P1 of the liquid cooling mechanism, and set the maximum allowable temperature T of the cell pack during charging and discharging based on the performance and safety requirements of the battery pack. max And a temperature difference threshold ΔT. First, the liquid cooling mechanism is activated and the entire battery cell assembly is cooled at maximum power P1. Then, the charging module 44 is activated and the charging power is slowly increased. At the same time, the temperature of each individual battery cell assembly is monitored in real time by the temperature sensor 21. When the detected value of the temperature sensor 21 reaches the preset maximum temperature value T... max At that time, controller 20 determines T max When the temperature difference between any of the remaining cell groups exceeds the threshold ΔT, the drive mechanism is immediately activated. This mechanism connects the liquid cooling system to the cell groups. At this point, the liquid cooling system allocates some power to the cell group with the highest temperature for heat dissipation, reducing the temperature of the high-temperature cell group. The temperatures of the other cell groups may rise slightly. Then, the charging module 44 is activated, and the charging power is slowly increased. The temperature of the cell groups continues to be monitored by the temperature sensor 21 until the temperature difference between any of the cell groups is less than ΔT, and the temperatures of all cell groups are uniform. At this point, the system reaches a new temperature equilibrium state, and the maximum charging power is obtained. The discharging module 45 repeats the above steps to obtain the maximum discharging power. After determining the maximum charging and discharging power, the discharging module 45 and the charging module 44 control the charging and discharging power to slowly increase to these maximum power values ​​for efficient charging and discharging operations.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lithium iron phosphate battery charging and discharging system, characterized in that, The utility model provides a battery pack, including casing and controller, the casing is equipped with baffle one and baffle two inside, baffle one and baffle two divide the inside from top to bottom of casing into cavity one, cavity two and cavity three, the controller is located in cavity one, and it includes charging module and discharging module, charging module is used to control the charging power of battery core group, and discharging module is used to control the discharging power of battery core group, baffle two is spaced apart and is provided with sliding slot, and battery core group is slidably arranged in the sliding slot, and battery core group includes battery core shell and battery core, the battery core shell is equipped with spiral heat dissipation channel in four side walls, the heat dissipation channel top is connected with four way valve, and its bottom is connected with three way valve no. 1, the outlet one of three way valve no. 1 is connected with exhaust pipe, and the outlet two is connected with liquid exhaust pipe, the exhaust pipe passes through the casing and is connected with outside, the liquid exhaust pipe is connected with heat exchanger, the heat exchanger is connected with cavity three through return pipe, the bottom surface of casing is equipped with sliding sleeve, the sliding sleeve is equipped with sliding rod, the top of sliding rod is connected to the bottom surface of battery group, the sliding sleeve is equipped with spiral spring, the side wall of sliding slot is equipped with locking mechanism, the bottom surface of baffle one is equipped with drive mechanism and calibration mechanism, the bottom of drive mechanism is equipped with push plate, the push plate is located above battery core group, the push plate is lowered and abuts with the top of battery core group, and battery core group is pushed down, cavity two is equipped with air cooling mechanism and liquid cooling mechanism, air cooling mechanism and liquid cooling mechanism are respectively driven and connected to four way valve inlet, calibration mechanism preferentially carries out heat dissipation to battery core group, a plurality of temperature sensors are arranged on battery core group, and the controller is electrically connected with four way valve, three way valve no. 1, drive mechanism, air cooling mechanism, liquid cooling mechanism and locking mechanism, 2. The lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that, The calibration mechanism includes moving mechanism, telescopic pipe, three way valve no. 2, connecting cover, connecting pipe and flow valve, the moving mechanism is arranged on the bottom surface of baffle one and is used to drive the movement of connecting cover, one end of the telescopic pipe is connected to three way valve no. 2, and the other end is connected to connecting cover, three way valve no. 2 is connected to main liquid pipe, the connecting cover is equipped with cavity no. 4, the flow valve is arranged on the bottom of connecting cover, and the connecting pipe is arranged on the top of four way valve and is connected to the inlet thereof.

3. The lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that, The drive mechanism includes first support plate, first screw rod, first motor, first moving block and first electric push rod, the first support plate is arranged on the bottom surface of baffle one, one end of the first screw rod is rotatably connected to the casing, the other end penetrates through the first support plate and is drivenly connected to the first motor, the first motor is arranged on the side surface of the first support plate, the first moving block is arranged on the first screw rod, and the first electric push rod is arranged on the bottom surface of the first moving block. The air cooling mechanism includes fan, main air pipe and secondary air pipe, the fan is arranged on the side wall of the casing, the main air pipe is arranged in cavity two, one end of the main air pipe is connected to the fan, and the other end extends and is located on one side of battery core group, the main air pipe is connected to four way valve through secondary air pipe, and the outlet of four way valve is connected to heat dissipation channel.

4. The lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that, The locking mechanism comprises a second electric push rod and a locking block, the sliding groove side wall is provided with a containing groove, the second electric push rod is arranged in the containing groove, and the telescopic end of the second electric push rod is connected to the side surface of the locking block; the locking block is arranged in the containing groove in a sliding mode and abuts against the side surface of the battery cell group.

5. The lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that, The moving mechanism comprises a second supporting plate, a second screw rod, a second motor, a second moving block and a third electric push rod, the second supporting plate is arranged on one bottom surface of the partition plate, one end of the second screw rod is rotatably connected to the shell, the other end of the second screw rod penetrates through the second supporting plate and is driven by the second motor, the second motor is arranged on the side surface of the second supporting plate, the second moving block is arranged on the second screw rod, the third electric push rod is arranged on the bottom surface of the second moving block, the telescopic end of the third electric push rod is provided with a push plate, and the second motor is electrically connected with the controller.

6. The lithium iron phosphate battery charging and discharging system according to claim 1, wherein, The connecting pipe top surface is provided with a sealing ring, the bottom of the sealing ring is nested in the top of the connecting pipe, and the top of the sealing ring is higher than the top surface of the connecting pipe.

7. The lithium iron phosphate battery charging and discharging system of claim 1, wherein, The connecting pipe top surface is provided with a sealing ring, the bottom of the sealing ring is nested in the top of the connecting pipe, and the top of the sealing ring is higher than the top surface of the connecting pipe.

8. A control method for the lithium iron phosphate battery charging and discharging system according to any one of claims 1-7, characterized in that, The connecting pipe top surface is provided with a sealing ring, the bottom of the sealing ring is nested in the top of the connecting pipe, and the top of the sealing ring is higher than the top surface of the connecting pipe. The method comprises the following steps: S01, setting the maximum working power of the liquid cooling mechanism; S02, setting the maximum charging temperature value of the battery cell group; S03, starting the liquid cooling mechanism and keeping the maximum working power; S04, slowly increasing the charging power of the charging module, when the detected value of the temperature sensor reaches the maximum value of the maximum charging temperature, obtaining the charging power corresponding to the maximum charging temperature; S05, the liquid cooling mechanism distributes part of the power to the battery cell group with the highest temperature for heat dissipation; S06, continuously slowly increasing the charging power until the temperatures of all the battery cell groups are uniform, the system reaches a new temperature balance state, and the maximum charging power is obtained at this time; S07, repeating the above steps S01 to S06 by the discharging module to obtain the maximum discharging power.

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