Lithium iron phosphate battery charging and discharging system and control method thereof

Abstract

The invention provides a lithium iron phosphate battery charging and discharging system and a control method thereof.The lithium iron phosphate battery charging and discharging system comprises a shell and a controller, the controller comprises a charging module and a discharging module, the charging module controls the charging power of a battery cell set, the discharging module controls the discharging power of the battery cell set, a second partition plate is provided with sliding grooves at intervals, and the battery cell set is arranged in the sliding grooves; the battery cell group comprises a battery cell shell and a battery cell, the battery cell shell is internally provided with a heat dissipation channel, the top of the battery cell shell is communicated with a four-way valve, the bottom of the battery cell shell is communicated with a three-way valve I, an outlet I of the three-way valve I is connected with an exhaust pipe, an outlet II of the three-way valve I is connected with a liquid discharge pipe, the exhaust pipe is communicated with the outside, and the liquid discharge pipe is communicated with a heat exchanger and then communicated with a cavity III through a return pipe; the air cooling mechanism and the liquid cooling mechanism are respectively connected to an inlet of the four-way valve in a driving manner; and a temperature sensor is arranged on the battery cell group. According to the invention, the single battery cell group can be cooled preferentially, the distribution of the overall heat dissipation power of the liquid cooling mechanism and the heat dissipation power of the single battery cell group is optimized, the wooden barrel effect is eliminated, and the charging and discharging power of the overall battery is improved.

Description

Technical Field

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

[0002] Lithium iron phosphate battery (LiFePO4), also known as LFP battery, is an important component of electric vehicles and large energy storage systems. In electric vehicles, lithium iron phosphate battery is the core power battery. The lithium iron phosphate battery charging and discharging system is mainly composed of battery pack, battery management system (BMS), charging device and discharge device. The working principle of this system is based on the embedding and de-embedding of lithium ions. During the charging process, lithium ions are de-embedded from the positive electrode material lithium iron phosphate, move to the negative electrode through the electrolyte and embed into it; the discharge process is the opposite, lithium ions are released from the negative electrode, move to the positive electrode again, and release electrical 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 functions and application scenarios. The charging system is responsible for converting external electrical energy into chemical energy inside the battery, while the discharging system converts the chemical energy inside the battery into external usable electrical energy. The charging and discharging power control system controls the charging and discharging power of the battery according to the needs of the system to meet the power requirements of the system. The control methods of the lithium iron phosphate battery charging and discharging system mainly include conventional charging, temperature controlled charging, balanced charging, conventional discharging, temperature controlled discharging and balanced discharging strategies. These strategies are designed to ensure that the battery remains efficient, stable and safe during the charging and discharging process.

[0004] In the prior art, in order to increase the voltage level, multiple cell groups are connected in series in sequence 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 quickly and reaches the temperature threshold of the cell group first, resulting in the barrel effect, which limits the charging and discharging power of the entire battery. In addition, when single-point heat accumulation occurs in a single cell group, it will affect the internal resistance of the battery, thereby affecting the overall battery performance. Summary of the invention

[0005] In view of this, the present invention proposes a lithium iron phosphate battery charging and discharging system, which is provided with a charging module and a discharging module. The charging module is used to control the charging power of the battery cell group, and the discharging module is used to control the discharging power of the battery cell group. An air cooling mechanism and a liquid cooling mechanism are provided. The maximum charging power and the maximum discharging power can be measured according to the temperature state of the battery cell group, and a mode of slowly increasing to the maximum charging and discharging power is adopted to match the charging power and the heat dissipation power, thereby ensuring that the battery temperature is stable within a safe range.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A lithium iron phosphate battery charging and discharging system and a control method thereof, comprising a shell and a controller, wherein a partition plate 1 and a partition plate 2 are arranged in the shell, wherein the partition plate 1 and the partition plate 2 divide the interior of the shell into a cavity 1, a cavity 2 and a cavity 3 from top to bottom, wherein the controller is arranged in the cavity 1, and comprises a charging module and a discharging module, wherein the charging module is used to control the charging power of a battery cell group, and the discharging module is used to control the discharging power of the battery cell group, wherein a slide groove is arranged at intervals between the partition plate 2, wherein a battery cell group is slidably arranged in the slide groove, wherein the battery cell group comprises a battery cell shell and a battery cell, wherein the four side walls of the battery cell shell are provided with a spiral heat dissipation channel, wherein the top of the heat dissipation channel is connected to a four-way valve, and the bottom thereof is connected to a three-way valve 1, wherein an outlet 1 of the three-way valve 1 is connected to an exhaust pipe, and an outlet 2 of the three-way valve 1 is connected to a liquid discharge pipe, and the exhaust pipe is connected to a liquid discharge pipe. The air duct passes through the shell and is connected to the outside. The drain pipe is connected to a heat exchanger, and the heat exchanger is connected to cavity three through a reflux pipe. A sliding sleeve is provided on the bottom surface of the shell, a sliding rod is provided in the sliding sleeve, and the top of the sliding rod is connected to the bottom surface of the battery pack. A coil spring is provided in the sliding sleeve, and a locking mechanism is provided on the side wall of the slide groove. A driving mechanism and a calibration mechanism are provided on the bottom surface of the partition one. A push plate is provided at the bottom of the driving mechanism, and the push plate is located above the battery cell group. An air cooling mechanism and a liquid cooling mechanism are provided in cavity two, and the air cooling mechanism and the liquid cooling mechanism are respectively driven and connected to the inlet of the four-way valve. The calibration mechanism can preferentially dissipate heat for the battery cell group. A plurality of temperature sensors are provided on the battery cell group. The controller is electrically connected to the four-way valve, the three-way valve one, the driving mechanism, the air cooling mechanism, the liquid cooling mechanism and the locking mechanism.

[0008] Preferably, the air cooling mechanism includes a fan, a main air duct and a secondary air duct, the fan is arranged on the side wall of the shell, the main air duct is arranged in cavity two, one end of which is connected to the fan, and the other end extends and is located on one side of the battery cell group, the main air duct is connected to the four-way valve through the secondary air duct, and the four-way valve outlet 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 cavity three, and the other end extends into cavity two through partition two and is located on one side of the battery cell group, the circulation pump is arranged on the main liquid pipe and is located in cavity two, and the main liquid pipe is connected to the four-way valve through the secondary liquid pipe.

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

[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 arranged in the receiving groove, and its telescopic end is connected to the side of the locking block, and the locking block is slidably arranged in the receiving groove and the side abuts against the side of the battery cell group.

[0012] Preferably, the calibration mechanism includes a moving mechanism, a telescopic tube, a three-way valve 2, a connecting cover, a connecting tube and a flow valve. The moving mechanism is arranged 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 three-way valve 2, and the other end is connected to the connecting cover. The three-way valve 2 is connected to the main liquid pipe. A cavity 4 is provided in the connecting cover. The flow valve is arranged at the bottom of the connecting cover. The connecting tube is arranged 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 screw rod, a second motor, a second moving block and a third electric push rod. The second support plate is arranged on a bottom surface of a partition. One end of the second screw rod is rotatably connected to the shell, and the other end passes through the second support plate and is driven to the second motor. The second motor is arranged on the side of the second support 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 to the controller.

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

[0015] Preferably, it further comprises an induction coil, wherein the induction coil is respectively arranged 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 coil.

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

[0017] S01. Setting the maximum operating power of the liquid cooling mechanism;

[0018] S02, setting 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, and when the temperature sensor detection value reaches the maximum value of the highest charging temperature, a larger charging power is obtained;

[0021] S05, the liquid cooling mechanism allocates part of the power to the battery cell group with the highest temperature for heat dissipation;

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

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

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] A charging module and a discharging module are set up. The charging module is used to control the charging power of the battery cell group, and the discharging module is used to control the discharging power of the battery cell group. An air cooling mechanism and a liquid cooling mechanism are set up. The air cooling mechanism has a hot air function. In a low temperature environment, the battery can be heated to improve the charging efficiency. The charging and discharging system is provided with a calibration mechanism to give priority to the heat dissipation of a single battery cell group, optimize the overall heat dissipation power of the liquid cooling mechanism and the distribution of the heat dissipation power of the single battery cell group, so that the temperature of the battery cell group is uniform and the system is in a temperature balance state, thereby eliminating the wooden barrel effect and improving the charging and discharging power of the overall battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a schematic diagram of the three-dimensional structure of a lithium iron phosphate battery charging and discharging system of the present invention;

[0028] Figure 2 It is a schematic cross-sectional structure diagram of a lithium iron phosphate battery charging and discharging system of the present invention;

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

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

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

[0032] Figure 6 for Figure 3 The enlarged view of point D in the middle;

[0033] Figure 7 It is a schematic structural diagram of a battery cell group of the present invention;

[0034] Figure numerals: 1, housing; 2, partition 1; 3, partition 2; 4, first support plate; 5, first screw rod; 6, first motor; 7, first moving block; 8, first electric push rod; 9, fan; 10, battery shell; 11, heat dissipation channel; 12, four-way valve; 13, main air duct; 14, secondary air duct; 15, exhaust duct; 16, slide; 17, slide rod; 18, sleeve; 19, coil spring; 20, controller; 21, temperature sensor; 22, battery; 23, cavity 1; 24, cavity 2; 25, cavity 3; 26, drain pipe; 27 , main liquid pipe; 28, second motor; 29, circulation pump; 30, secondary liquid pipe; 31, receiving tank; 32, second electric push rod; 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, reflux 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 screw rod; 50, second moving block; 51, third electric push rod. DETAILED DESCRIPTION

[0035] In order to better understand the technical content of the present invention, a specific embodiment is provided below, and the present invention is further described in conjunction with the accompanying drawings.

[0036] See also Figures 1 to 7The present invention provides a lithium iron phosphate battery charging and discharging system, including a shell 1 and a controller 20. The shell 1 is provided with a partition 2 and a partition 3. The partition 2 and the partition 3 divide the inside of the shell 1 from top to bottom into a cavity 1 23, a cavity 24 and a cavity 3 25. The cavity 3 25 stores a cooling liquid. The controller 20 is arranged in the cavity 1 23, and includes a charging module 44 and a discharging module 45. The charging module 44 is used to control the charging power of the battery pack. The discharge module 45 is used to control the discharge power of the battery cell group. The partition 23 is provided with a slide groove 16, and the battery cell group is slidably arranged in the slide groove 16. The battery cell group includes a battery cell shell 10 and a battery cell 22. The battery cell shell 10 is made of a metal material with good thermal conductivity. The four side walls of the battery cell shell 10 are provided with a spiral heat dissipation channel 11. The top of the heat dissipation channel 11 is connected to a four-way valve 12, and the bottom is connected to a three-way valve 42. The outlet of the three-way valve 42 is connected to an exhaust pipe 15, and its outlet The second cavity is connected to a drain pipe 26, the exhaust pipe 15 passes through the shell 1 and is connected to the outside, the drain pipe 26 is connected to a heat exchanger 40, and the heat exchanger 40 is connected to the cavity three 25 through a reflux pipe 41. A sliding sleeve is provided on the bottom surface of the shell 1, a sliding rod 17 is provided in the sliding sleeve, and the top of the sliding rod 17 is connected to the bottom surface of the battery pack. A coil spring 19 is provided in the sliding sleeve, and a locking mechanism is provided on the side wall of the slide groove 16. A driving mechanism and a calibration mechanism are provided on the bottom surface of the partition plate 2. The bottom of the driving mechanism A push plate 47 is provided, and the push plate 47 is located above the battery cell group. An air cooling mechanism and a liquid cooling mechanism are provided in the cavity 24, and the air cooling mechanism and the liquid cooling mechanism are respectively connected to the inlet of the four-way valve 12. The calibration mechanism can preferentially dissipate heat for the battery cell group. A plurality of temperature sensors 21 are provided on the battery cell group. The controller 20 is electrically connected to the four-way valve 12, the three-way valve 1 42, the driving mechanism, the air cooling mechanism, the liquid cooling mechanism and the locking mechanism. The battery cell shell 10 is made of metal material with good thermal conductivity.

[0037] When the charging and discharging system is working, the battery charging operation is set in two modes: normal charging mode and fast charging mode. When the charging module 44 is in the normal charging mode, the temperature sensor 21 is first started to monitor the temperature of the battery cell group. The temperature sensor 21 monitors the temperature of the battery cell group in real time. When the temperature is lower than the minimum value of the normal charging temperature range of the battery cell group, the controller 20 starts the fan 9, and the fan 9 generates hot air and heats the battery cell group through the heat dissipation channel 11, raising the temperature of the battery cell group to the normal charging range, which is conducive to improving the charging efficiency. The charging module 44 increases the charging power in stages. As the battery cell group is charged, the battery cell group generates heat energy. When the temperature sensor 21 detects that the temperature of the battery cell group is higher than the maximum value of the normal range, the charging module 44 charges stably at this stage power, starts the fan 9 to generate airflow and enters the heat dissipation channel 11 through the main air duct 13 and the secondary air duct 14 to cool the battery cell group, thereby keeping the temperature of the battery cell group within a normal range, which is beneficial to the charging and discharging operations of the battery cell group; when the charging module 44 is in the fast charging mode, first start the temperature sensor 21 to monitor the temperature of the battery cell group. The temperature sensor 21 monitors the temperature of the battery cell group in real time. When the temperature is lower than the minimum value of the normal charging temperature range of the battery cell group, the controller 20 starts the fan 9, and the fan 9 generates hot air and heats the battery cell group through the heat dissipation channel 11 to increase the temperature of the battery cell group to within the normal charging range, and then stops the air cooling mechanism and starts The liquid cooling mechanism is activated to dissipate heat for the battery cell group, and dissipates heat for all the battery cell groups as a whole at the maximum power P1, and then the charging module 44 is started, and the charging power is slowly increased. When the detection value of the temperature sensor 21 on one of the battery cell groups reaches the preset maximum temperature value Tmax, the controller 20 determines that the temperature difference between Tmax and any remaining battery cell group exceeds the threshold value ΔT, and immediately starts the calibration mechanism, which connects the liquid cooling mechanism and the battery cell group. At this time, the liquid cooling mechanism allocates part of the power to the battery cell group with the highest temperature for heat dissipation, and the temperature of the high-temperature battery cell group decreases, and the temperature of other battery cell groups may rise slightly. Then the charging module 44 is started, and the charging power is slowly increased. The temperature of the battery cell group is continuously monitored through the temperature sensor 21 until the temperature difference of any battery cell group is less than ΔT. When the temperature of each battery cell group is uniform, the system reaches a new temperature equilibrium state, and the maximum charging power is obtained at this time. The discharge module 45 repeats the above steps to obtain the maximum discharge power. After determining the maximum charging power and the maximum discharging power, the discharging module 45 and the charging module 44 will control the charging and discharging power to slowly increase to these maximum power values ​​to perform efficient charging and discharging operations. The charging and discharging system can give priority to heat dissipation of a single battery cell group, optimize the overall heat dissipation power of the liquid cooling mechanism and the distribution of the heat dissipation power of the single battery cell group, eliminate the barrel effect, and improve the charging and discharging power of the overall 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 arranged on the side wall of the shell 1, the main air duct 13 is arranged in the cavity 24, one end of which is connected to the fan 9, and the other end extends and is located on one side of the battery cell group, the main air duct 13 is connected to the four-way valve 12 through the secondary air duct 14, and 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 cell group in real time. When the temperature is lower than the minimum value of the normal range, the controller 20 starts the fan 9, and 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 the battery cells. As the battery cell group is charged or discharged, the battery cell group generates heat energy. When the temperature sensor 21 detects that the temperature of the battery cell group 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 the battery cell group, thereby keeping the temperature of the battery cell group within a normal range, which is beneficial to the charging and discharging of the battery cell group.

[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 cavity three 25, and the other end passes through partition two 3 and extends into cavity two 24 and is located on one side of the battery cell group. The circulation pump 29 is arranged on the main liquid pipe 27 and is located in cavity two 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 operate under high power conditions, the battery cell group will generate a large amount of heat. At this time, the air cooling mechanism can no longer meet the heat dissipation needs. The controller 20 starts the liquid cooling mechanism, first starts the four-way valve 12 and the three-way valve 2 46, so that the main liquid pipe 27 is connected with the heat dissipation channel 11, and the heat dissipation channel 11 is connected with the drain pipe 26, and then starts the circulation pump 29. The circulation pump 29 draws the coolant stored in the cavity three 25 into the main liquid pipe 27, and the coolant enters the heat dissipation channel 11 from the main liquid pipe 27 through the secondary liquid pipe 30, thereby dissipating the heat of the battery cell group and improving the heat dissipation efficiency of the battery cell group.

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

[0043] The driving mechanism is used to drive the push plate 47 to move so that the push plate 47 moves to the top of the battery cell group. When the battery cell group needs to be lowered, the first motor 6 is first started, and the rotation of the first motor 6 drives the first screw 5 to rotate, thereby driving the first moving block 7 to move along the axis of the first screw 5. The movement of the first moving block 7 drives the first electric push rod 8 to move to the top of the battery cell group to be lowered, and then the first electric push rod 8 is started. The telescopic end of the first electric push rod 8 extends to drive the push plate 47 to descend, and the push plate 47 descends and abuts against the top of the battery cell group, thereby pushing the battery cell group 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 arranged 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 arranged in the receiving groove 31 and the side abuts against the side of the battery cell group.

[0045] The locking mechanism is used to fix the battery cell group in the slide groove 16. When the temperature sensor 21 detects that the temperature of the battery pack exceeds the preset value, the controller 20 starts the locking mechanism, first starts the second electric push rod 32, and the telescopic end of the second electric push rod 32 shortens to drive the locking block 33 to move, loosening the battery pack, and then starts the driving mechanism. The driving mechanism pushes the battery cell group downward, and the bottom of the battery cell group enters the cavity three 25 and enters the coolant. Then it stops the driving mechanism and starts the locking mechanism at the same time to lock the battery cell group, thereby achieving the effect of emergency cooling.

[0046] Preferably, the calibration mechanism includes a moving mechanism, a telescopic tube 43, a three-way valve 46, a connecting cover 35, a connecting pipe 34 and a flow valve 39. The moving mechanism is arranged 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 three-way valve 46, and the other end is connected to the connecting cover 35. The three-way valve 46 is connected to the main liquid pipe 27. A cavity 36 is provided in the connecting cover 35. The flow valve 39 is arranged at the bottom of the connecting cover 35. The flow valve 39 is used to detect the coolant flow rate, so as to determine whether the coolant is blocked. The connecting pipe 34 is arranged at the top of the four-way valve 12 and connected to its inlet.

[0047] When a certain battery cell group has a high temperature, in order to avoid overheating of a local area of ​​the battery, the calibration mechanism is used to preferentially dissipate heat for the battery cell group. When the calibration mechanism is started, the moving mechanism is first started, and the moving mechanism drives the connection cover 35 to move to the top of the connection pipe 34 and completes the docking, and then the circulation pump 29 is started, and the circulation pump 29 draws the coolant from the conduit, and at the same time the three-way valve is started to connect the conduit and the telescopic pipe 43, and the coolant flows from the conduit into the telescopic pipe 43 and into the cavity 436, and enters the heat dissipation channel 11 through the flow valve 39 and the docking pipe, so that the liquid cooling mechanism allocates part of the power to preferentially dissipate heat for the battery cell group.

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

[0049] The moving mechanism is used to drive the battery cell group to move down along the slide 16, so that the bottom of the battery cell group drops and immerses in the coolant to achieve the effect of cooling. When the moving mechanism is started, the second motor 28 is started first, and the rotation of the second motor 28 drives the second screw 49 to rotate, thereby driving the second moving block 50 to move along the axis of the second screw 49, and the movement of the second moving block 50 drives the third electric push rod 51 to move, thereby driving the push plate 47 to be located directly above the battery cell group to be lowered, and then the third electric push rod 51 is started, and the telescopic end of the third electric push rod 51 is extended to drive the push rod to drop and abut against the top of the battery cell group, thereby realizing the function of lowering the battery cell group.

[0050] Preferably, a sealing ring 38 is provided on the top surface of the connecting pipe 34 , and the bottom of the sealing ring 38 is embedded in the top of the connecting pipe 34 , and the top of the sealing ring 38 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 tube 34. When the connecting cover 35 and the connecting tube 34 are connected, the lower bottom surface of the connecting cover 35 abuts against the sealing ring 38. The sealing ring 38 has a certain elasticity and 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 tube 34 from directly contacting each other.

[0052] Preferably, it further comprises an induction coil, which is respectively arranged on the bottom surface of the connection cover 35 and the side surface of the connection pipe 34, and the controller 20 is electrically connected to the induction coil.

[0053] When the moving mechanism drives the connecting cover 35 and the connecting tube 34 to dock, the induction coil arranged on the side of the connecting tube 34 is an active coil. With different numbers of turns, different magnetic fluxes can be generated by a preset current. The induction coil arranged at the bottom of the connecting cover 35 is a passive coil. When the two induction coils are close to 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. The controller 20 can move the connecting cover 35 to the connecting tube 34 on the top of a specific battery pack for docking according to the different currents generated. 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 combined, which is beneficial to improve the sealing.

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

[0055] S01. Setting the maximum operating power of the liquid cooling mechanism;

[0056] S02, setting 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, and when the temperature sensor detection value reaches the maximum value of the highest charging temperature, a larger charging power is obtained;

[0059] S05, the liquid cooling mechanism allocates part of the power to the battery cell group with the highest temperature for heat dissipation;

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

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

[0062] Set the maximum power P1 of the liquid cooling mechanism, and set the maximum temperature T allowed for the battery pack during the charging and discharging process according to the performance and safety requirements of the battery pack. max and a temperature difference threshold ΔT. First, the liquid cooling mechanism is started and the entire battery cell group is cooled at the maximum power P1, then the charging module 44 is started and the charging power is slowly increased. At the same time, the temperature of each single battery cell group is monitored in real time through the temperature sensor 21. When the detection value of the temperature sensor 21 reaches the preset maximum temperature value T max When T max When the temperature difference with any remaining battery cell group exceeds the threshold value of ΔT, the driving mechanism is immediately started, and the driving mechanism connects the liquid cooling mechanism and the battery cell group. At this time, the liquid cooling mechanism allocates part of the power to the battery cell group with the highest temperature for heat dissipation, and the temperature of the high-temperature battery cell group decreases. The temperature of other battery cell groups may rise slightly. Then the charging module 44 is started, and the charging power is slowly increased. The temperature of the battery cell group continues to be monitored through the temperature sensor 21 until the temperature difference of any battery cell group is less than ΔT. When the temperature of each battery cell group is uniform, the system reaches a new temperature equilibrium state, and the maximum charging power is obtained at this time. The discharge module 45 repeats the above steps to obtain the maximum discharge power. After determining the maximum charging power and the maximum discharging power, the discharge module 45 and the charging module 44 will control the charging and discharging power to slowly increase to these maximum power values ​​to perform 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A lithium iron phosphate battery charging and discharging system, characterized in that: It includes a shell and a controller, wherein a partition 1 and a partition 2 are arranged in the shell, wherein the partition 1 and the partition 2 divide the inside of the shell into a cavity 1, a cavity 2 and a cavity 3 from top to bottom, wherein the controller is arranged in the cavity 1, and includes a charging module and a discharging module, wherein the charging module is used to control the charging power of the battery cell group, and the discharging module is used to control the discharging power of the battery cell group, wherein a slide groove is arranged at intervals between the partition 2, wherein a battery cell group is slidably arranged in the slide groove, wherein the battery cell group includes a battery cell shell and a battery cell, wherein the four side walls of the battery cell shell are provided with a spiral heat dissipation channel, wherein the top of the heat dissipation channel is connected to a four-way valve, and the bottom thereof is connected to a three-way valve 1, wherein an outlet 1 of the three-way valve 1 is connected to an exhaust pipe, and an outlet 2 of the three-way valve 1 is connected to a liquid discharge pipe, wherein the exhaust pipe passes through the shell and is connected to the outside The drain pipe is connected with a heat exchanger, and the heat exchanger is connected with cavity three through a reflux pipe. A sliding sleeve is provided on the inner bottom surface of the shell, and a sliding rod is provided in the sliding sleeve. The top of the sliding rod is connected to the bottom surface of the battery pack. A coil spring is provided in the sliding sleeve, and a locking mechanism is provided on the side wall of the slide groove. A driving mechanism and a calibration mechanism are provided on the bottom surface of the partition one, and a push plate is provided at the bottom of the driving mechanism, and the push plate is located above the battery cell group. An air cooling mechanism and a liquid cooling mechanism are provided in cavity two, and the air cooling mechanism and the liquid cooling mechanism are respectively driven and connected to the inlet of the four-way valve. The calibration mechanism can preferentially dissipate heat for the battery cell group. A plurality of temperature sensors are provided on the battery cell group. The controller is electrically connected to the four-way valve, the three-way valve one, the driving mechanism, the air cooling mechanism, the liquid cooling mechanism and the locking mechanism.

2. A lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that: The air cooling mechanism includes a fan, a main air duct and a secondary air duct. The fan is arranged on the side wall of the shell, and the main air duct is arranged in the second 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 group. The main air duct is connected to the four-way valve through the secondary air duct, and the outlet of the four-way valve is connected to the heat dissipation channel.

3. A lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that: 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 cavity three, and the other end passes through partition two and extends into cavity two and is located on one side of the battery cell group. The circulation pump is arranged on the main liquid pipe and is located in cavity two. The main liquid pipe is connected to the four-way valve through the secondary liquid pipe.

4. A lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that: The driving mechanism includes a first support plate, a first screw rod, a first motor, a first moving block and a first electric push rod. The first support plate is arranged on a bottom surface of a partition. One end of the first screw rod is rotatably connected to the shell, and the other end passes through the first support plate and is driven to the first motor. The first motor is arranged on the side 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.

5. A lithium iron phosphate battery charging and discharging system according to claim 1, characterized in that: 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 arranged in the receiving groove, and its telescopic end is connected to the side of the locking block. The locking block is slidably arranged in the receiving groove and the side abuts against the side of the battery cell group.

6. A lithium iron phosphate battery charging and discharging system according to claim 3, characterized in that: The calibration mechanism includes a moving mechanism, a telescopic tube, a three-way valve 2, a connecting cover, a connecting tube and a flow valve. The moving mechanism is arranged on the bottom surface of a partition plate and is used to drive the connecting cover to move. One end of the telescopic tube is connected to the three-way valve 2, and the other end is connected to the connecting cover. The three-way valve 2 is connected to the main liquid pipe. A cavity 4 is provided in the connecting cover. The flow valve is arranged at the bottom of the connecting cover. The connecting tube is arranged at the top of the four-way valve and connected to its inlet.

7. A lithium iron phosphate battery charging and discharging system according to claim 7, characterized in that: The moving mechanism includes a second support plate, a second screw rod, a second motor, a second moving block and a third electric push rod. The second support plate is arranged on a bottom surface of a partition plate. One end of the second screw rod is rotatably connected to the shell, and the other end passes through the second support plate and is driven to the second motor. The second motor is arranged on the side of the second support 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 to the controller.

8. A lithium iron phosphate battery charging and discharging system according to claim 6, characterized in that: A sealing ring is provided on the top surface of the connecting pipe, and the bottom of the sealing ring is embedded in the top of the connecting pipe, and the top of the sealing ring is higher than the top surface of the connecting pipe.

9. A lithium iron phosphate battery charging and discharging system according to claim 6, characterized in that: It also includes an induction coil, which is respectively arranged 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 coil.

10. A control method for a lithium iron phosphate battery charging and discharging system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S01. Setting the maximum operating power of the liquid cooling mechanism; S02, setting the maximum charging temperature value of the battery pack; S03, start the liquid cooling mechanism and maintain it at maximum operating power; S04, the charging module slowly increases the charging power, and when the temperature sensor detection value reaches the maximum value of the highest charging temperature, a larger charging power is obtained; S05, the liquid cooling mechanism allocates part of the power to the battery cell group with the highest temperature for heat dissipation; S06, continue to slowly increase the charging power until the temperature of each battery cell group is uniform and the system reaches a new temperature equilibrium state, at which time the maximum charging power is obtained; S07. The discharge module repeats the above steps S01 to S06 to obtain the maximum discharge power.

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