System and method for testing environmental temperature and humidity characteristics in power battery pack

Abstract

The invention discloses a power battery pack internal environment temperature and humidity characteristic test system which comprises a simulation module, a shell, a liquid cooling plate, a condensation sensor, a waterproof ventilation valve, a thermocouple, a wireless temperature and humidity sensor, a temperature and humidity test box, a power source, a water vat, a water pump, a refrigerating machine, a temperature controller, a water inlet pipeline and a water outlet pipeline. The shell is arranged on the liquid cooling plate and is sealed with the liquid cooling plate to form an internal space, and the shell and the liquid cooling plate are arranged in the temperature and humidity test box; the simulation module and the condensation sensor are arranged on the liquid cooling plate, the waterproof ventilation valve is installed on the side face of the shell, the thermocouple is arranged on the simulation module, the wireless temperature and humidity sensor is arranged on the inner wall of the shell, the temperature controller is connected with the refrigerating machine, the power source is connected with the simulation module and the temperature controller, and the refrigerating machine is arranged below the water tank. The water pump and a temperature probe of the temperature controller are arranged in cooling liquid of the water tank, the water inlet pipeline is connected with the water pump and a cooling liquid inlet of the liquid cooling plate, one end of the water outlet pipeline is arranged in cooling liquid of the water tank, and the other end is connected with a cooling liquid outlet of the liquid cooling plate.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and more particularly, to a device and method for simulating the service environment of a power battery pack and detecting the internal temperature and humidity response and the characteristics of condensation distribution of the power battery pack. Background Art

[0002] In recent years, the electric vehicle industry has developed rapidly. However, with the sharp increase in the vehicle ownership, the frequent occurrence of new energy vehicle fire accidents has attracted wide attention. According to the data of the Fire and Rescue Bureau of the Emergency Management Department of China, from January to October 2024, a total of 2,105 electric vehicle fires were reported, an increase of 17% compared with 2023, and the proportion of thermal runaway of power batteries exceeded 80%. Typical accident modes include: thermal runaway during charging, electrolyte leakage after wading (such as the case of spontaneous combustion of a flooded vehicle), internal short circuit caused by mechanical abuse, and short circuit induced by condensation in the battery pack under a humid and hot environment. It is worth noting that the erosion effect of the humid and hot environment on the battery system has not been fully emphasized. For example, the proportion of electrochemical corrosion and insulation failure caused by condensation has been increasing year by year in accident investigations, but the current standards (such as the IP67 protection level) are mostly for static waterproof design, and there is a lack of systematic evaluation of water vapor penetration and phase change condensation under dynamic humid and hot alternating working conditions. In addition, existing thermal management technologies mostly focus on temperature field control, and there are still blind spots in the coordinated control of humidity field and condensation risk.

[0003] Generally speaking, a waterproof and breathable valve is installed in the power battery pack, which has the functions of waterproof, dustproof and pressure balancing. When the temperature and pressure in the battery pack fluctuate, the battery pack can inhale or exhale some gases through the waterproof and breathable valve, so as to achieve the pressure balance inside and outside the pack. However, the waterproof and breathable valve can only block liquid droplets with a larger diameter and has no blocking effect on water vapor molecules in the air. When the battery pack is in a humid environment, water vapor molecules can easily enter the battery pack through the waterproof and breathable valve and accumulate, thus increasing the risk of condensation inside the pack.

[0004] The humidity problem is directly related to temperature, and the interior of the battery pack has the characteristic of coexistence of heat sources (such as battery modules) and cold sources (such as liquid cooling plates). When the humid air flowing inside the battery pack is heated by the high-temperature module and then comes into contact with the low-temperature liquid cooling plate, it is extremely likely to cause condensation, resulting in an increase in the liquid water inside the battery pack, seriously threatening the safety of the battery pack and even the whole vehicle. In addition, considering that electric vehicles are long-distance transportation tools and will experience diverse climate conditions during driving, their battery packs also need to withstand the influence of various complex working conditions during service. Under the combined action of the internal environment and the external environment of the battery pack, there will be a coupling effect of multiple physical fields such as heat transfer, water vapor transfer, fluid flow, and phase change between the internal and external environments. The humid heat flow field of the internal microenvironment will become more complex, further increasing the contingency and randomness of the condensation in terms of distribution location, occurrence time, and conditions inside the battery pack, thus adding difficulty to the prevention and control work of condensation.

[0005] Current research mostly focuses on single temperature field regulation or optimization of heat dissipation efficiency, lacking systematic research on the coupling mechanism between the humidity field and the temperature field. For example, although traditional liquid cooling systems can effectively reduce the battery temperature, in a high-humidity environment, the heat exchange between the coolant and the external environment easily leads to condensation on the surface of the battery pack housing, instead exacerbating the humidity accumulation inside the pack. In addition, research on the condensation problem mostly stays at the level of static environment simulation, and the transient generation and diffusion laws of condensation under dynamic alternating humid heat working conditions (such as large day-night temperature difference, rapid temperature rise after rainfall) are still unclear, resulting in a lack of pertinence in the design of protective measures. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defect that the prior art cannot predict the generation time and distribution location of internal condensation in the power battery pack under various environmental climates, and to provide a test system and method for the temperature and humidity characteristics of the internal environment of the power battery pack. Through the test method, the temperature and humidity change characteristics and condensation evolution laws inside the power battery pack under various climate conditions are detected and analyzed by comparison, which are used for the judgment and verification of whether condensation is generated inside the power battery pack and the amount of condensation generated, providing research data reference for the condensation prevention and control work.

[0007] In order to achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0008] A test system for the temperature and humidity characteristics of the internal environment of a power battery pack includes a simulation module, a housing, a liquid cooling plate, a condensation sensor, a waterproof breathable valve, a thermocouple, a wireless temperature and humidity sensor, a temperature and humidity test chamber, a data acquisition instrument, a host computer, a power supply, a water tank, a water pump, a refrigerator, a temperature controller, an inlet pipe, and an outlet pipe. The housing is framed on the liquid cooling plate and is hermetically connected to the liquid cooling plate. The housing and the liquid cooling plate are placed inside the temperature and humidity test chamber. The housing and the liquid cooling plate enclose an internal space as the internal environment of the power battery pack for temperature and humidity characteristic tests;

[0009] The simulation module and the condensation sensor are arranged on the liquid cooling plate, the waterproof breathable valve is installed on the side of the housing, the thermocouples are arranged at each measuring point of the simulation module, the wireless temperature and humidity sensor is arranged on the inner wall of the housing, the data acquisition instrument is connected to the thermocouples, the upper computer is connected to the data acquisition instrument, the temperature controller is connected to the refrigerator, the power supply is respectively connected to the simulation module and the temperature controller, the refrigerator is arranged under the water tank, the temperature probes of the water pump and the temperature controller are arranged in the coolant of the water tank, one end of the inlet pipe is connected to the water pump, and the other end is connected to the coolant inlet of the liquid cooling plate; one end of the outlet pipe is arranged in the coolant of the water tank, and the other end is connected to the coolant outlet of the liquid cooling plate;

[0010] The thermocouples are used to measure the temperatures of each measuring point of the simulation module; the wireless temperature and humidity sensor is used to measure the temperature and humidity of the air inside the housing; the temperature and humidity test chamber is used to control the temperature and humidity inside the chamber to simulate the service environment of the power battery pack; the refrigerator is used to cool down the coolant in the water tank; the temperature controller is used to control whether the refrigerator cools down according to the temperature of the coolant in the water tank; the data acquisition instrument is used to collect the temperature data of each measuring point of the simulation module measured by the thermocouples and transmit them to the upper computer, and the upper computer is used to observe the temperatures of each measuring point of the simulation module in real time.

[0011] Furthermore, the simulation module, the housing, the liquid cooling plate and the waterproof breathable valve serve as the battery pack simulation device; the thermocouples, the wireless temperature and humidity sensor, the condensation sensor, the data acquisition instrument and the upper computer serve as the data acquisition device; the temperature and humidity test chamber serves as the environment simulation device; the power supply, the water tank, the water pump, the refrigerator and the temperature controller serve as the external energy supply device.

[0012] Furthermore, the simulation module includes a plurality of simulated battery cells, and each simulated battery cell includes an aluminum plate, a heating film and an acrylic plate. The heating film is arranged between the aluminum plate and the acrylic plate, and the heating film is connected to the power supply.

[0013] Furthermore, the liquid cooling plate serves as the bottom plate of the housing, and the liquid cooling plate and the housing are hermetically connected by hot melt adhesive.

[0014] Furthermore, the ways for the temperature and humidity test chamber to control the temperature and humidity inside the chamber include constant value control and program control. Constant value control keeps the temperature and humidity inside the chamber at a preset constant value, and program control makes the temperature and humidity inside the chamber change dynamically according to the operation curve.

[0015] A method for testing the temperature and humidity characteristics of the internal environment of a power battery pack, which is applied to the test system for the temperature and humidity characteristics of the internal environment of the power battery pack described in any one of the above, includes the following steps:

[0016] S1: Set the heating power of the simulation module by adjusting the number of heating films connected to the power supply, set the coolant inlet flow rate by the water pump, and set the coolant inlet temperature by the refrigerator and the temperature controller;

[0017] S2: Set the temperature and humidity of the air inside the temperature and humidity test chamber to simulate the initial external environment when the battery pack starts to work, and arrange the dew sensor, thermocouple, and wireless temperature and humidity sensor.

[0018] S3: After the temperature and humidity inside the temperature and humidity test chamber are stable, energize the heating film in the simulation module to generate heat, start the water pump, and make the coolant flow into the liquid cooling plate at a constant temperature and speed.

[0019] S4: Control the temperature and humidity inside the temperature and humidity test chamber to change dynamically according to the operation curve, record the start time and end time when the dew sensor gives an audible alarm until the test ends.

[0020] S5: Take out the battery pack simulation device from the temperature and humidity test chamber, record the dew distribution position and generation quantity, read the measurement data of the thermocouple and wireless temperature and humidity sensor and analyze them.

[0021] Further, the simulation module includes multiple layers of material layers stacked alternately, and the various parameters of the simulation module are calculated by the following formula:

[0022]

[0023] In the formula, ρ represents the density of the simulation module; ρ i represents the density of the i-th material layer of the simulation module; V i is the volume of the i-th material layer of the simulation module; C p represents the specific heat capacity of the simulation module; C pi represents the specific heat capacity of the i-th material layer of the simulation module; k S represents the thermal conductivity in the series direction of the simulation module; k p represents the thermal conductivity in the parallel direction of the simulation module; l i represents the thickness of the i-th material layer of the simulation module; k i represents the thermal conductivity of the i-th material layer of the simulation module.

[0024] Further, the coolant inlet flow rate is controlled by adjusting the water pump power.

[0025] The coolant inlet temperature is controlled by the refrigerator and the thermostat: when the coolant temperature is higher than the temperature set by the thermostat, the thermostat energizes the refrigerator, and the refrigerator cools down the coolant in the water tank; when the coolant temperature drops to the temperature set by the thermostat, the thermostat de-energizes the refrigerator to keep the coolant in the water tank at the temperature set by the thermostat.

[0026] Further, the temperature and humidity test chamber maintains the temperature and humidity inside the chamber at a constant value and keeps it for a preset period through set-point control to ensure that the initial temperature and humidity of the internal environment and the external environment of the battery pack simulation device are the same.

[0027] Further, the number of the electrically heated films is set according to the heat release power corresponding to the simulated battery discharge rate; the temperature and humidity operation curve inside the temperature and humidity test chamber is set according to the simulated climate type.

[0028] Compared with the prior art, the present invention constructs a battery pack simulation device according to the structural characteristics of the power battery pack, and the battery pack simulation device has the same sealing and structural characteristics as the real battery pack. The waterproof breathable valve is the only mass transfer channel between the internal and external environments of the battery pack, the simulation module is the main heat source, the liquid cooling plate is the main cold source, the heating power of the simulation module, the temperature and flow rate of the coolant can all be independently controlled, and various real working conditions of the battery pack can be simulated. The temperature and humidity inside the battery pack are monitored in real time through the thermocouples and wireless temperature and humidity sensors arranged inside it, and the temperature and humidity characteristics shown by the battery pack under various working conditions are reflected.

[0029] The present invention selects a temperature and humidity test chamber as the environmental simulation device and places the battery pack simulation device inside the temperature and humidity test chamber. Various dynamic alternating environmental loads can be simulated by adjusting the temperature and humidity inside the temperature and humidity test chamber to restore various service environments of the power battery pack.

[0030] The present invention combines the battery pack simulation device, the environmental simulation device, the data acquisition device and the external power supply device into a test platform for the temperature and humidity characteristics of the internal environment of the power battery pack, which is used to conduct tests and analyses on the mutual influence and interaction between the internal environment and the external environment of the battery pack under different working conditions, and to test and observe the temperature and humidity action law of the battery pack and the generation of condensation. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of a test system for the temperature and humidity characteristics of the internal environment of a power battery pack.

[0032] Figure 2 It is a schematic flow diagram of a test method for the temperature and humidity characteristics of the internal environment of a power battery pack.

[0033] Figure 3 It is a specific flow chart of a test method for the temperature and humidity characteristics of the internal environment of a power battery pack.

[0034] 1 - Simulation module; 2 - Housing; 3 - Liquid cooling plate; 4 - Condensation sensor; 5 - Waterproof breathable valve; 6 - Thermocouple; 7 - Wireless temperature and humidity sensor; 8 - Temperature and humidity test chamber; 9 - Data acquisition instrument; 10 - Host computer; 11 - Power supply; 12 - Water tank; 13 - Water pump; 14 - Refrigerator; 15 - Temperature controller; 16 - Inlet pipeline; 17 - Outlet pipeline. Detailed Embodiments

[0035] The following further describes the test system and method for the temperature and humidity characteristics of the internal environment of the power battery pack of the present invention in conjunction with the drawings and specific embodiments.

[0036] Please refer to Figure 1 , the present invention discloses a test system for the temperature and humidity characteristics of the internal environment of a power battery pack, which includes a simulation module 1, a housing 2, a liquid cooling plate 3, a condensation sensor 4, a waterproof and breathable valve 5, a thermocouple 6, a wireless temperature and humidity sensor 7, a temperature and humidity test chamber 8, a data acquisition instrument 9, a host computer 10, a power supply 11, a water tank 12, a water pump 13, a refrigerator 14, a temperature controller 15, a water inlet pipe 16 and a water outlet pipe 17.

[0037] The simulation module 1, the housing 2, the liquid cooling plate 3 and the waterproof and breathable valve 5 serve as a battery pack simulation device, and the battery pack simulation device is placed in the temperature and humidity test chamber 8. The thermocouple 6, the wireless temperature and humidity sensor 7, the condensation sensor 4, the data acquisition instrument 9 and the host computer 10 serve as data acquisition devices. The temperature and humidity test chamber 8 serves as an environmental simulation device. The power supply 11, the water tank 12, the water pump 13, the refrigerator 14 and the temperature controller 15 serve as an external energy supply device. The housing 2 is framed on the liquid cooling plate 3 and is hermetically connected to the liquid cooling plate 3. The housing 2 and the liquid cooling plate 3 are placed in the temperature and humidity test chamber 8, and the internal space formed by enclosing the housing 2 and the liquid cooling plate 3 is used as the internal environment of the power battery pack for temperature and humidity characteristic tests.

[0038] The simulation module 1 and the condensation sensor 4 are arranged on the liquid cooling plate 3. Since the liquid cooling plate 3 is the main cold source inside the battery pack during operation and is a high-incidence area of condensation, when condensation occurs on the condensation sensor 4, a buzzer will sound. The waterproof and breathable valve 5 is installed on the side of the housing 2, and the waterproof and breathable valve 5 is the only mass transfer channel between the internal and external environments of the battery pack. The thermocouple 6 is arranged at each measuring point of the simulation module 1 to monitor the temperature distribution of the simulation module 1 under working conditions. The wireless temperature and humidity sensor 7 is arranged on the inner wall of the housing 2 to monitor the temperature and humidity of the humid air inside the battery pack.

[0039] The data acquisition instrument 9 is connected to the thermocouple 6, and the host computer 10 is connected to the data acquisition instrument 9. The temperature controller 15 is connected to the refrigerator 14, and the power supply 11 is respectively connected to the simulation module 1 and the temperature controller 15. The refrigerator 14 is arranged below the water tank 12, and the temperature probes of the water pump 13 and the temperature controller 15 are arranged in the coolant of the water tank 12. One end of the water inlet pipe 16 is connected to the water pump 13, and the other end is connected to the coolant inlet of the liquid cooling plate 3. One end of the water outlet pipe 17 is arranged in the coolant of the water tank 12, and the other end is connected to the coolant outlet of the liquid cooling plate 3.

[0040] The thermocouple 6 is used to measure the temperatures of various measuring points of the analog module 1. The wireless temperature and humidity sensor 7 is used to measure the temperature and humidity of the air inside the housing 2. The temperature and humidity test chamber 8 is used to control the temperature and humidity inside the chamber to simulate the service environment of the power battery pack, that is, the external environment of the battery pack. The refrigerator 14 is used to cool down the coolant in the water tank 12. The temperature controller 15 is used to control whether the refrigerator 14 cools down according to the temperature of the coolant in the water tank 12. The data acquisition instrument 9 is used to collect the temperature data of various measuring points of the analog module 1 measured by the thermocouple 6 and transmit it to the host computer 10, and the host computer 10 is used to observe the temperatures of various measuring points of the analog module 1 in real time.

[0041] The analog module 1 includes a plurality of analog battery cells. Each analog battery cell includes an aluminum plate, a heating film, and an acrylic plate. The heating film is arranged between the aluminum plate and the acrylic plate, and the heating film is connected to the power supply 11, and the power supply 11 supplies power to the heating film to generate heat. The liquid cooling plate 3 serves as the bottom plate of the housing 2, and the liquid cooling plate 3 and the housing 2 are hermetically connected by hot melt adhesive. The ways for the temperature and humidity test chamber 8 to control the temperature and humidity inside the chamber include constant value control and program control. Constant value control keeps the temperature and humidity inside the chamber at a preset constant value, and program control makes the temperature and humidity inside the chamber change dynamically according to the operation curve.

[0042] The liquid cooling plate 3, the water pump 13, the inlet pipe 16, and the outlet pipe 17 form a circulating liquid cooling loop. The water pump 13 is the input end of the liquid cooling loop. The coolant reaches the liquid cooling plate 3 through the inlet pipe 16. The liquid cooling plate 3 is responsible for dissipating heat from the analog module 1. The coolant heated by the analog module 1 then returns to the water tank 12 through the outlet pipe 17.

[0043] Whether the refrigerator 14 is powered on and working depends on the temperature controller 15. The temperature probe of the temperature controller 15 monitors the temperature of the coolant in the water tank 12 in real time. When the temperature of the coolant is higher than the temperature set by the temperature controller 15, the temperature controller 15 powers on the refrigerator 14, and the refrigerator 14 cools down the coolant in the water tank 12; when the temperature of the coolant drops to the preset temperature of the temperature controller 15, the temperature controller 15 cuts off the power supply of the refrigerator 14, and the refrigerator 14 stops working. Through the control of the refrigerator 14 and the temperature controller 15, the coolant is kept at a constant temperature.

[0044] Please refer to Figure 2 and Figure 3 , the present invention also discloses a test method for the temperature and humidity characteristics of the internal environment of a power battery pack, which is applied to the test system for the temperature and humidity characteristics of the internal environment of a power battery pack described in any one of the above, and includes the following steps:

[0045] S1: Set the battery pack working conditions, including the module heating power, the coolant inlet flow rate, and the coolant inlet temperature. Set the module heating power by adjusting the number of heating films connected to the power supply 11, set the coolant inlet flow rate by the water pump 13, and set the coolant inlet temperature by the refrigerator 14 and the temperature controller 15.

[0046] S2: Set the external environmental climate (i.e., the temperature and humidity inside the temperature and humidity test chamber 8), including the setting of environmental temperature and environmental humidity. Set the temperature and humidity of the air inside the temperature and humidity test chamber 8 to simulate the initial external environment when the battery pack starts to work. Place the condensation sensor 4 on the liquid cooling plate, place the thermocouple 6 on the simulation module 1, and place the wireless temperature and humidity sensor 7 on the inner wall of the housing 2.

[0047] S3: Perform fixed-value control on the temperature and humidity test chamber 8. After the temperature and humidity inside the temperature and humidity test chamber 8 are stable, energize the heating film in the simulation module 1 to generate heat, and start the water pump 13 in the water tank 12 to make the coolant flow into the liquid cooling plate 3 at a constant temperature and speed.

[0048] S4: Change the fixed-value control of the temperature and humidity test chamber 8 to program control, and control the temperature and humidity inside the temperature and humidity test chamber 8 to change dynamically according to the operation curve. During the test process, observe the temperature changes of each measuring point of the simulation module 1 through the host computer 10, record the start time and end time when the condensation sensor 4 gives an audible alarm until the test ends.

[0049] S5: Take out the battery pack simulation device from the temperature and humidity test chamber 8, and disassemble and observe the battery pack simulation device. Record the condensation distribution position and the generated quantity, read the measurement data of the thermocouple 6 and the wireless temperature and humidity sensor 7 and perform analysis.

[0050] The simulation module 1 includes multiple layers of material layers stacked alternately. The parameters of the simulation module 1 are calculated through the following formula:

[0051]

[0052]

[0053] In the formula, ρ represents the density of the simulation module 1; ρ i represents the density of the i-th material layer of the simulation module 1; V i is the volume of the i-th material layer of the simulation module 1; C p represents the specific heat capacity of the simulation module 1; C pi represents the specific heat capacity of the i-th material layer of the simulation module 1; k S represents the thermal conductivity of the simulation module 1 in the series direction; k p represents the thermal conductivity of the simulation module 1 in the parallel direction; l i represents the thickness of the i-th material layer of the simulation module 1; k i represents the thermal conductivity of the i-th material layer of the simulation module 1.

[0054] The flow rate of the coolant inlet is controlled by adjusting the power of the water pump 13. The temperature of the coolant inlet is controlled by the chiller 14 and the thermostat 15: when the coolant temperature is higher than the set temperature of the thermostat 15, the thermostat 15 powers on the chiller 14, and the chiller 14 cools down the coolant in the water tank 12; when the coolant temperature drops to the set temperature of the thermostat 15, the thermostat 15 powers off the chiller 14 to keep the coolant in the water tank 12 at the set temperature of the thermostat 15.

[0055] The temperature and humidity test chamber 8 maintains the temperature and humidity inside the chamber at a constant value through fixed-value control and holds it for a preset period to ensure that the initial temperature and humidity of the internal environment and the external environment of the battery pack simulation device are consistent. The heating power of the simulation module 1 is determined by the number of energized heating films, and the number of energized heating films is set according to the heat release power corresponding to the simulated battery discharge rate. The temperature and humidity operation curve inside the temperature and humidity test chamber 8 is set according to the simulated climate type.

[0056] In summary, the present invention constructs a battery pack simulation device according to the structural characteristics of the power battery pack. The battery pack simulation device has the same sealing and structural characteristics as the real battery pack. The waterproof breathable valve is the only mass transfer channel between the internal and external environments of the battery pack. The simulation module is the main heat source, and the liquid cooling plate is the main cold source. The heating power of the simulation module, the temperature and flow rate of the coolant can all be independently controlled, which can simulate various real working conditions of the battery pack, and can monitor the temperature and humidity of the internal environment of the battery pack in real time through the thermocouples and wireless temperature and humidity sensors arranged inside it, reflecting the temperature and humidity characteristics of the battery pack under various working conditions.

[0057] The present invention combines the battery pack simulation device, the environment simulation device, the data acquisition device and the external power supply device into a test platform for the temperature and humidity characteristics of the internal environment of the power battery pack, which is used to conduct tests and analyses on the mutual influence and interaction between the internal environment and the external environment of the battery pack under different working conditions, and to test and observe the temperature and humidity action law of the battery pack and the generation of condensation.

[0058] The above description is a detailed description of the preferred and feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications made under the technical spirit disclosed by the present invention shall fall within the scope of the patent covered by the present invention.

Claims

1. An in-environment temperature and humidity characteristic test system for a power battery pack, characterized in that, It includes a simulation module, a housing, a liquid cooling plate, a condensation sensor, a waterproof breathable valve, a thermocouple, a wireless temperature and humidity sensor, a temperature and humidity test chamber, a data acquisition instrument, a host computer, a power supply, a water tank, a water pump, a refrigerator, a temperature controller, an inlet pipe and an outlet pipe. The housing is framed on the liquid cooling plate and is hermetically connected to the liquid cooling plate. The housing and the liquid cooling plate are placed inside the temperature and humidity test chamber. The housing and the liquid cooling plate enclose an internal space to be used as the internal environment of the power battery pack for temperature and humidity characteristic tests. The simulation module and the condensation sensor are arranged on the liquid cooling plate. The waterproof breathable valve is installed on the side of the housing. The thermocouple is arranged at each measuring point of the simulation module. The wireless temperature and humidity sensor is arranged on the inner wall of the housing. The data acquisition instrument is connected to the thermocouple. The host computer is connected to the data acquisition instrument. The temperature controller is connected to the refrigerator. The power supply is respectively connected to the simulation module and the temperature controller. The refrigerator is arranged below the water tank. The temperature probe of the water pump and the temperature controller is arranged in the coolant of the water tank. One end of the inlet pipe is connected to the water pump, and the other end is connected to the coolant inlet of the liquid cooling plate. One end of the outlet pipe is arranged in the coolant of the water tank, and the other end is connected to the coolant outlet of the liquid cooling plate. The thermocouple is used to measure the temperature of each measuring point of the simulation module. The wireless temperature and humidity sensor is used to measure the temperature and humidity of the air inside the housing. The temperature and humidity test chamber is used to control the temperature and humidity inside the chamber to simulate the service environment of the power battery pack. The refrigerator is used to cool down the coolant in the water tank. The temperature controller is used to control whether the refrigerator cools down according to the temperature of the coolant in the water tank. The data acquisition instrument is used to collect the temperature data of each measuring point of the simulation module measured by the thermocouple and transmit it to the host computer, and the host computer is used to observe the temperature of each measuring point of the simulation module in real time.

2. The test system for the internal environmental temperature and humidity characteristics of the power battery pack according to claim 1, wherein The simulation module, the housing, the liquid cooling plate and the waterproof breathable valve are used as the battery pack simulation device. The thermocouple, the wireless temperature and humidity sensor, the condensation sensor, the data acquisition instrument and the host computer are used as the data acquisition device. The temperature and humidity test chamber is used as the environment simulation device. The power supply, the water tank, the water pump, the refrigerator and the temperature controller are used as the external energy supply device.

3. The test system for the environmental temperature and humidity characteristics inside the power battery pack according to claim 1, characterized in that, The simulation module includes a plurality of simulated battery cells. Each simulated battery cell includes an aluminum plate, a heating film and an acrylic plate. The heating film is arranged between the aluminum plate and the acrylic plate, and the heating film is connected to the power supply.

4. The test system for the internal environmental temperature and humidity characteristics of the power battery pack according to claim 1, characterized in that The liquid cooling plate serves as the bottom plate of the housing, and the liquid cooling plate and the housing are hermetically connected by hot melt adhesive.

5. The test system for the internal environmental temperature and humidity characteristics of the power battery pack according to claim 1, characterized in that, The ways for the temperature and humidity test chamber to control the temperature and humidity inside the chamber include constant value control and program control. Constant value control keeps the temperature and humidity inside the chamber at a preset constant value, and program control makes the temperature and humidity inside the chamber change dynamically according to the operation curve.

6. A test method for the ambient temperature and humidity characteristics inside a power battery pack, characterized in that Applied to the temperature and humidity characteristic test system for the internal environment of the power battery pack described in any one of claims 1 to 5, it includes the following steps: S1: Set the heating power of the simulation module by adjusting the number of heating films connected to the power supply, set the flow rate of the coolant inlet by the water pump, and set the temperature of the coolant inlet by the refrigerator and the temperature controller. S2: Set the temperature and humidity of the air inside the chamber by the temperature and humidity test chamber to simulate the initial external environment when the battery pack starts to work, and arrange the condensation sensor, the thermocouple and the wireless temperature and humidity sensor. S3: After the temperature and humidity inside the temperature and humidity test chamber become stable, energize the heating film in the simulation module to generate heat, and start the water pump to make the coolant flow into the liquid cooling plate at a constant temperature and speed. S4: Control the temperature and humidity inside the temperature and humidity test chamber to change dynamically according to the operation curve, record the start time and end time when the condensation sensor gives an audible alarm until the test ends. S5: Take out the battery pack simulation device from the temperature and humidity test chamber, record the condensation distribution position and the generated quantity, read the measurement data of the thermocouple and the wireless temperature and humidity sensor and analyze them.

7. The test method for the ambient temperature and humidity characteristics inside the power battery pack according to claim 6, wherein The simulation module includes multiple layers of material layers stacked alternately. The parameters of the simulation module are calculated through the following formula: where ρ represents the density of the simulation module; ρ i represents the density of the i-th material layer of the simulation module; V i represents the volume of the i-th material layer of the simulation module; C p represents the specific heat capacity of the simulation module; C pi represents the specific heat capacity of the i-th material layer of the simulation module; k S represents the thermal conductivity in the series direction of the simulation module; k p represents the thermal conductivity in the parallel direction of the simulation module; l i represents the thickness of the i-th material layer of the simulation module; k i represents the thermal conductivity of the i-th material layer of the simulation module.

8. The test method for the internal environmental temperature and humidity characteristics of the power battery pack according to claim 6, characterized in that The coolant inlet flow rate is controlled by adjusting the water pump power. The coolant inlet temperature is controlled by the refrigerator and the thermostat: when the coolant temperature is higher than the temperature set by the thermostat, the thermostat energizes the refrigerator, and the refrigerator cools down the coolant in the water tank; when the coolant temperature drops to the temperature set by the thermostat, the thermostat de-energizes the refrigerator to keep the coolant in the water tank at the temperature set by the thermostat.

9. The test method for the internal environmental temperature and humidity characteristics of the power battery pack according to claim 6, characterized in that The temperature and humidity test chamber maintains the temperature and humidity inside the chamber at a constant value through fixed value control and keeps it for a preset period to ensure that the initial temperature and humidity of the internal environment and the external environment of the battery pack simulation device are the same.

10. The test method for the internal environmental temperature and humidity characteristics of the power battery pack according to claim 6, characterized in that The number of energized heating films is set according to the heat release power corresponding to the simulated battery discharge rate; the temperature and humidity operation curve inside the temperature and humidity test chamber is set according to the simulated climate type.

Images