Battery Pack Temperature Pre-Regulation System, Control Method, Electric Vehicle and Medium

Abstract

The present invention provides a pre-adjustment system for the temperature of an electric vehicle battery pack, which includes a battery pack, a heating element, a refrigerating element, a battery pack temperature sensor, an ambient temperature sensor, an ambient anemometer, a positioning element and a networking element. The vehicle owner can make an appointment for the next startup time of the vehicle, and the vehicle performs thermal management in advance according to the external environmental conditions to ensure a smooth startup of the vehicle for travel. The present invention simultaneously considers the influence of environmental temperature and wind speed factors on the heat exchange of the battery pack, corrects the weather forecast information by combining specific measured data, and pre-calibrates the heat exchange ratio values under different wind speeds. Therefore, the considered factors are comprehensive, scientific and reasonable. The pre-adjustment logic of the battery pack is simple and easy to use, and can accurately adjust the temperature of the battery pack at the appointed startup moment, having the advantages of high efficiency and energy saving.

Description

Technical Field

[0001] The present invention relates to the field of electric vehicles, and in particular to a battery pack temperature pre-regulation system, a control method, an electric vehicle and a medium. Background Art

[0002] Currently, electric vehicles are mainly powered by lithium-ion battery packs located on their chassis. The charging and discharging of lithium-ion battery packs need to be carried out in a suitable temperature environment. Although electric vehicles have certain thermal management functions during operation, when electric vehicles are parked for a long time in an environment with high or low ambient temperature, the temperature of the battery pack of the electric vehicle will tend to be consistent with the ambient temperature due to heat exchange with the surrounding environment. In this case, when the owner needs to start the vehicle again, the thermal management system of the electric vehicle will take a long time to adjust the temperature of the battery pack to a suitable range, which will inevitably affect the owner's car experience.

[0003] For example, an electric car using a lithium iron phosphate lithium-ion battery pack is parked outdoors in the cold overnight, and the owner needs to use the car the next morning. When the owner starts the vehicle, since the temperature of the battery pack is basically the same as the air temperature, the thermal management system of the electric car needs to work for a certain period of time to heat the battery pack temperature to an appropriate range and have full power output capability.

[0004] Therefore, it is urgent to develop battery pack temperature pre-adjustment technology so that car owners can pre-adjust the battery pack temperature to an appropriate range when starting electric vehicles parked in harsh climates such as high or low temperatures. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a battery pack temperature pre-regulation system, control method, electric vehicle and medium that are scientific and reasonable, simple in logic, easy to use, efficient and energy-saving, and take comprehensive factors into consideration.

[0006] According to a first aspect of the present invention, a system for pre-regulating the temperature of an electric vehicle battery pack is provided, which is used to adjust the temperature of an electric vehicle battery pack in a parked state to an appropriate range according to a time preset by the owner. The system includes a battery pack, a heating element, a cooling element, a battery pack temperature sensor, an ambient temperature sensor, an ambient anemometer, a positioning element, and a networking element, wherein:

[0007] The heating element and the cooling element are used to provide heating and cooling for the battery pack respectively;

[0008] The battery pack temperature sensor is used to measure the battery pack temperature;

[0009] The ambient temperature sensor and the ambient anemometer are used to measure the air temperature and wind speed of the external environment of the electric vehicle respectively;

[0010] The positioning element is used to obtain the geographical location of the electric vehicle;

[0011] The networking element is used for communication with the vehicle owner and for sending a query request to the weather forecast provider to obtain the temperature and wind speed information at a certain time at the geographical location of the electric vehicle.

[0012] Optionally, in the above-mentioned electric vehicle battery pack temperature pre-adjustment system, the heating element is a PTC heater and the heating power is constant.

[0013] Optionally, in the above-mentioned electric vehicle battery pack temperature pre-adjustment system, the refrigeration element is a vehicle-mounted air conditioner and the refrigeration power is constant.

[0014] Optionally, in the above-mentioned electric vehicle battery pack temperature pre-adjustment system, the positioning element is a satellite positioning chip.

[0015] Optionally, in the above-mentioned electric vehicle battery pack temperature pre-adjustment system, the number of the battery pack temperature sensors is one or more. When the number of the battery pack temperature sensors is more than one, their arithmetic mean value is used as the final measurement value.

[0016] Optionally, the above-mentioned electric vehicle battery pack temperature pre-adjustment system further includes a controller, and the heating element, the refrigeration element, the battery pack temperature sensor, the ambient temperature sensor, the ambient anemometer, the positioning element and the networking element are all electrically connected to the controller.

[0017] According to the second aspect of the present invention, there is provided a control method applied to the electric vehicle battery pack temperature pre-adjustment system described in any one of the above. The method is as follows: after the electric vehicle parks, the vehicle owner makes an appointment with the electric vehicle for the next starting time of the vehicle. After the controller obtains the next starting time of the vehicle, the following steps are sequentially executed:

[0018] Step S1: Measure and obtain the ambient air temperature T0 and the ambient wind speed V0, and obtain the air temperature t0 and the wind speed v0 at the geographical location of the electric vehicle at the measurement time given by the weather forecast provider through the networking element;

[0019] Step S2: Obtain the predicted air temperature t1 and the predicted wind speed v1 at the geographical location of the electric vehicle at the next starting time given by the weather forecast provider through the networking element;

[0020] Step S3: Calculate the corrected air temperature t2 and the corrected wind speed v2 at the geographical location of the electric vehicle at the next starting time:

[0021] t2 = t1 + T0 - t0 (1)

[0022] v2 = v1 + V0 - v0 (2)

[0023] Step S4: Compare the corrected temperature t2 obtained in step S3 with the lower limit T of the allowable operating temperature of the battery pack min and the upper limit T max of the allowable operating temperature: If T min ≤t2≤T max , stop the execution of all subsequent steps; otherwise, proceed to step S5;

[0024] Step S5: Calculate the pre-adjustment time τ for the battery pack temperature:

[0025] If t2 < T min , then:

[0026] τ = cm(T min −t2) / [P h −0.5k(T min −t2)] (3)

[0027] If t2 > T max , then:

[0028] τ = cm(t2 − T max ) / [P r −0.5k(t2 − T max )] (4)

[0029] Here, t2 is the corrected temperature obtained in step S3, c and m are the average specific heat capacity and total mass of the battery pack respectively, T min and T max are the lower limit and upper limit of the allowable operating temperature of the battery pack respectively, P h and P r are the heating power of the heating element and the cooling power of the cooling element respectively, and k is the heat transfer ratio between the battery pack and the environment;

[0030] The value of the heat transfer ratio k is determined in the following way:

[0031] The controller pre-stores a table of heat transfer ratio values between the battery pack and the environment at different wind speeds;

[0032] Based on the corrected wind speed v2 obtained in step S4, find the two closest wind speed values and their corresponding heat transfer ratio values from the table;

[0033] Use the linear interpolation calculation method to obtain the heat transfer ratio value corresponding to the corrected wind speed v2, which is the value of the heat transfer ratio k;

[0034] Step S6: At a time τ from the next start-up moment, start the pre-adjustment of the battery pack until the temperature of the battery pack is within the range of the lower limit and upper limit of the allowable operating temperature: If t2 < T min , then start heating the battery pack; if t2 > Tmax , the cooling of the battery pack is started.

[0035] Optionally, for the control method of the above-mentioned electric vehicle battery pack temperature pre-adjustment system, the values of the heat exchange ratio at different wind speeds in the heat exchange ratio value table are obtained by the following method before the vehicle leaves the factory:

[0036] Place the electric vehicle in a wind tunnel with a constant wind temperature. At a series of different wind speeds, heat or cool the battery pack at a constant power respectively until the battery pack temperature remains stable. Record the battery pack temperature, and divide the heating or cooling power by the absolute value of the difference between the wind temperature and the battery pack temperature to obtain the heat exchange ratio value corresponding to the wind speed.

[0037] According to the third aspect of the present invention, there is provided an electric vehicle, which is equipped with the electric vehicle battery pack temperature pre-adjustment system described in any one of the above.

[0038] Furthermore, this electric vehicle applies the control method of the electric vehicle battery pack temperature pre-adjustment system described in any one of the above.

[0039] According to the fourth aspect of the present invention, there is provided a computer-readable storage medium storing multiple control instructions, and the control instructions are adapted to be loaded by a processor to execute the control method of the electric vehicle battery pack temperature pre-adjustment system described in any one of the above.

[0040] Next, the beneficial effects are introduced in combination with the principle of the technical solution of the present invention.

[0041] The idea of the battery pack temperature pre-adjustment of the present invention is as follows: After the electric vehicle parks, the vehicle owner makes an appointment for the next vehicle start time according to the vehicle use needs; the battery pack temperature pre-adjustment system pre-heats or cools the battery pack in advance according to the ambient air temperature and wind speed at the vehicle start time, so that it just adjusts the temperature to the lower limit or the upper limit of the battery pack's permitted operating temperature at the appointed vehicle start time.

[0042] The above pre-adjustment operation needs to be precise according to the actual situation: neither over-adjusting - not allowing the temperature to exceed the lower limit of the battery pack's permitted operating temperature or be lower than the upper limit of the permitted operating temperature too much, nor under-adjusting - ensuring that the temperature is within the range from the lower limit to the upper limit of the battery pack's permitted operating temperature; neither adjusting too early nor too late - trying to just adjust to the right temperature at the vehicle start time, not wasting too much energy, and at the same time not requiring the vehicle owner to wait.

[0043] Referring to step S5 of the technical solution of the present invention, to achieve precise pre-adjustment operation, the key lies in accurately calculating the time τ required for pre-adjusting the battery pack temperature. For this purpose, it is necessary to rely on the calculations of heat transfer and fully consider the meteorological conditions of the parking environment. According to the principles of heat transfer, on the premise of a constant specific heat capacity, the temperature change of the battery pack is proportional to the change in its internal thermal energy. And the change in the internal thermal energy of the battery pack per unit time is equal to the difference between the heat generation power and the heat exchange power of the battery pack. Among them, the heat generation power is the heating or cooling power of the battery pack itself, and the heat exchange power is the heat exchange power between the battery pack and the environment.

[0044] For example, assume that an electric vehicle is parked outdoors in cold weather and needs to reach the lower limit T of the permitted operating temperature of the battery pack when starting next time. min The predicted value of the ambient air temperature after correction at startup is t2, the average specific heat capacity and total mass of the battery pack are c and m respectively, and the heating power of the heating element is P. h Since the time taken for the temperature pre-adjustment stage is not very long, it is approximately considered that the ambient air temperature and wind speed remain unchanged throughout the temperature pre-adjustment process. According to the predicted value v2 of the corrected wind speed, the heat exchange ratio between the battery pack and the environment at this wind speed is found to be k.

[0045] Then, during the temperature pre-adjustment stage, the increase in the internal thermal energy of the battery pack = (the heating power of the battery pack - the heat dissipation power of the battery pack) * the time τ for pre-adjusting the battery pack temperature, that is:

[0046] cm(T min - t2) = τ[P h - 0.5k(T min - t2)]

[0047] Among them, the heat dissipation power of the battery pack is the product of the average value of the difference between the battery pack and the ambient air temperature during the pre-adjustment stage and the heat exchange ratio. The ambient air temperature during the pre-adjustment stage is constantly t2, and the battery pack temperatures at the start and end times of the pre-adjustment are t2 and T respectively min (Since the vehicle has been parked for a long time, the battery pack temperature at the start time of the pre-adjustment tends to be the same as the ambient temperature), then the differences between the battery pack and the ambient air temperature at the start and end times are 0 and T min - t2 respectively. Therefore, the average value of the difference between the battery pack and the ambient air temperature throughout the pre-adjustment process is 0.5 * (0 + T min - t2) = 0.5(T min - t2).

[0048] Furthermore, in order to more accurately calculate the time τ for pre-adjusting the battery pack temperature as described above, the technical solution of the present invention includes the following three important technical features.

[0049] First, the influence of ambient temperature and wind speed on the heat exchange power of the battery pack is considered. The atmosphere in the parking environment conducts convective heat exchange with the vehicle body and chassis, and indirectly with the battery pack. Under the same conditions, the greater the difference between the ambient temperature and the battery pack temperature, or the greater the wind speed, the stronger the heat exchange. In some well-known technical solutions in the art, the influence of ambient wind speed on the heat exchange of the battery pack is not considered, so they are not detailed and comprehensive enough.

[0050] Second, the difference between the specific parking location environment status of the vehicle and the local weather forecast information is considered, and the weather forecast information is corrected based on this actual difference. As is well known, although today's weather forecast service providers can give weather forecast information for a certain area based on satellite positioning data, the forecast information is for general outdoor conditions. There is often a certain difference between the temperature and wind speed at the actual specific parking location and the general outdoor meteorological conditions of its geographical location. For example, the weather forecast gives the temperature and wind speed information for a certain street, while the actual parking location may be in the outdoor parking lot of that street, or in an underground parking lot, or under an eaves or in a corner of a wall. Then there is often a certain difference between the temperature and wind speed at the specific parking point and the general outdoor conditions in the local area. Therefore, in the technical solution of the present invention, after the vehicle owner sends a reserved start time, the ambient temperature and wind speed at the parking position are measured immediately, and compared with the local weather information reported by the weather forecast service provider at the current moment to obtain the difference between the two, and the forecast values of the ambient temperature and wind speed at the start time are corrected according to the difference situation.

[0051] Third, the heat exchange ratio k value at different wind speeds is tested and calibrated under controllable conditions in the laboratory before leaving the factory, and stored in the controller in the form of a table in advance for calling. Thus, it is more targeted, making the calculation required for the pre-adjustment operation process simpler and more accurate, and also providing a technical idea and means different from the well-known technology.

[0052] Therefore, the present invention takes into account both the influence of ambient temperature and wind speed factors on the heat exchange of the battery pack, corrects the weather forecast information by combining specific measured data, and pre-calibrates the heat exchange ratio k value at different wind speeds. Therefore, the considered factors are comprehensive, scientific and reasonable. The pre-adjustment logic of the battery pack is simple and convenient to use, and can just adjust the battery pack temperature to the appropriate level at the reserved start time, having the advantages of high efficiency and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a flowchart of the control method of the pre-adjustment system for the temperature of the electric vehicle battery pack in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] The present invention will be further described below with reference to the drawings and embodiments.

[0055] The present invention provides a temperature pre-regulation system for an electric vehicle battery pack, which is used to adjust the temperature of an electric vehicle battery pack in a parked state to an appropriate range according to a time preset by the owner. The system includes a battery pack, a heating element, a cooling element, a battery pack temperature sensor, an ambient temperature sensor, an ambient anemometer, a positioning element, and a networking element, wherein:

[0056] The heating element and the cooling element are used to provide heating and cooling for the battery pack respectively;

[0057] The battery pack temperature sensor is used to measure the battery pack temperature;

[0058] The ambient temperature sensor and the ambient anemometer are used to measure the air temperature and wind speed of the external environment of the electric vehicle respectively;

[0059] The positioning element is used to obtain the geographical location of the electric vehicle;

[0060] The networking element is used for communication with the vehicle owner and for sending a query request to a weather forecast provider to obtain the temperature and wind speed information at the geographical location of the electric vehicle at a certain time.

[0061] In one embodiment, the battery pack is arranged above the chassis of the electric vehicle, and the ambient temperature sensor and the ambient anemometer are arranged on the lower surface of the chassis of the electric vehicle.

[0062] Preferably, in the above-mentioned electric vehicle battery pack temperature pre-regulation system, the heating element is a PTC heater, and the heating power is constant.

[0063] Preferably, in the above-mentioned electric vehicle battery pack temperature pre-regulation system, the refrigeration element is an on-board air conditioner, and the refrigeration power is constant.

[0064] Preferably, the PTC heater and the vehicle air conditioner are both controlled by a battery thermal management system (BMS) and can be used to directly or indirectly heat and cool the battery pack.

[0065] Preferably, in the above-mentioned electric vehicle battery pack temperature pre-regulation system, the positioning element is a satellite positioning chip.

[0066] Specifically, the satellite positioning chip is a GPS and / or Beidou navigation chip.

[0067] Preferably, in the above-mentioned electric vehicle battery pack temperature pre-regulation system, the number of the battery pack temperature sensors is one or more. When the number of the battery pack temperature sensors is multiple, their arithmetic mean is used as the final measurement value.

[0068] Preferably, the above-mentioned electric vehicle battery pack temperature pre-adjustment system further includes a controller, and the heating element, the refrigeration element, the battery pack temperature sensor, the ambient temperature sensor, the ambient anemometer, the positioning element and the networking element are all electrically connected to the controller.

[0069] Specifically, the controller is used to control the start and stop of the heating element and the refrigeration element, and perform information interaction with the battery pack temperature sensor, the ambient temperature sensor, the ambient anemometer, the positioning element and the networking element.

[0070] In one embodiment, the controller is integrated in the vehicle controller.

[0071] The present invention also provides a control method applied to the above-mentioned electric vehicle battery pack temperature pre-adjustment system. The method is that after the electric vehicle parks, the vehicle owner makes a reservation for the next starting time of the vehicle with the electric vehicle.

[0072] In one embodiment, the vehicle owner conducts Internet communication with the controller of the electric vehicle through a mobile phone APP to inform the controller of the next starting time of the vehicle.

[0073] After the controller obtains the next starting time of the vehicle, the following steps are sequentially executed:

[0074] Step S1: Measure the ambient air temperature T0 and the ambient wind speed V0, and obtain the air temperature t0 and the wind speed v0 at the location where the electric vehicle is located at the measurement moment given by the weather forecast provider through the networking element.

[0075] Step S2: Obtain the predicted air temperature t1 and the predicted wind speed v1 at the location where the electric vehicle is located at the next starting time given by the weather forecast provider through the networking element.

[0076] Specifically, the controller obtains the current geographical location of the electric vehicle through the positioning element, and sends the geographical location together with the next starting time of the electric vehicle to the weather forecast provider through the Internet to request weather forecast services.

[0077] Step S3: Calculate the corrected air temperature t2 and the corrected wind speed v2 at the location where the electric vehicle is located at the next starting time:

[0078] t2 = t1 + T0 - t0 (1)

[0079] v2 = v1 + V0 - v0 (2)

[0080] Step S4: Compare the corrected air temperature t2 obtained in Step S3 with the lower limit T min and the upper limit T max of the permitted operating temperature of the battery pack: If T min ≤ t2 ≤ T max, then stop the execution of all subsequent steps; otherwise, proceed to step S5;

[0081] Step S5: Calculate the time τ required for pre-adjusting the battery pack temperature:

[0082] If t2 < T min , then:

[0083] τ = cm(T min - t2) / [P h - 0.5k(T min - t2)] (3)

[0084] If t2 > T max , then:

[0085] τ = cm(t2 - T max ) / [P r - 0.5k(t2 - T max )] (4)

[0086] Here, t2 is the corrected air temperature obtained in step S3, c and m are the average specific heat capacity and total mass of the battery pack respectively, T min and T max are the lower and upper limits of the allowable operating temperature of the battery pack respectively, P h and P r are the heating power of the heating element and the cooling power of the cooling element respectively, and k is the heat exchange ratio between the battery pack and the environment;

[0087] The value of the heat exchange ratio k is determined in the following manner:

[0088] The controller pre-stores a table of heat exchange ratio values between the battery pack and the environment at different wind speeds;

[0089] Based on the corrected wind speed v2 obtained in step S4, find the two wind speed values closest to it in the table and their corresponding heat exchange ratio values;

[0090] Use the linear interpolation calculation method to obtain the heat exchange ratio value corresponding to the corrected wind speed v2, which is the value of the heat exchange ratio k.

[0091] Specifically, if the two wind speed values closest to the corrected wind speed v2 found in the table are v a and v b , where v a < v b , and the heat exchange ratio values corresponding to v a and v b are k a and k b respectively, then the heat exchange ratio corresponding to the corrected wind speed v2 is:

[0092] k = ka +(k b -k a )*(v2-v a ) / (v b -v a )

[0093] Step S6: At the moment when the time to the next startup moment is τ, start the pre-adjustment of the battery pack until the temperature of the battery pack is within the range of the lower limit of the permitted operating temperature and the upper limit of the permitted operating temperature: If t2 < T min , then start heating the battery pack; if t2 > T max , then start cooling the battery pack.

[0094] Furthermore, for the control method of the above-mentioned electric vehicle battery pack temperature pre-adjustment system, the values of the heat exchange ratio at different wind speeds in the heat exchange ratio value table are obtained by the following method before the vehicle leaves the factory:

[0095] Place the electric vehicle in a wind tunnel with a constant wind temperature. At a series of different wind speeds, heat or cool the battery pack at a constant power respectively until the temperature of the battery pack remains stable. Record the temperature of the battery pack. Divide the heating or cooling power by the absolute value of the difference between the wind temperature and the battery pack temperature to obtain the heat exchange ratio value corresponding to the wind speed.

[0096] In one embodiment, at a certain wind speed, the wind temperature is kept constant at 20 °C, and the battery pack is heated at a constant power of 5 kW through a resistance wire mesh evenly embedded in the battery pack. After testing for a period of time, the temperature of the battery pack is stably maintained at 25 °C. Then the heat exchange ratio k at this wind speed = 5 kW / |20 °C - 25 °C| = 1 kW / °C. The above heat exchange ratio value of 1 kW / °C means that at a certain wind speed, when the temperature difference between the battery pack and the ambient air temperature is 1 °C, the heat exchange power between the battery pack and the environment is 1 kW.

[0097] The present invention also provides an electric vehicle, which is equipped with the above-mentioned electric vehicle battery pack temperature pre-adjustment system.

[0098] Furthermore, this electric vehicle applies the control method of the above-mentioned electric vehicle battery pack temperature pre-adjustment system.

[0099] The present invention provides a computer-readable storage medium, which stores multiple control instructions. The control instructions are suitable for being loaded by a processor to execute the control method of the above-mentioned electric vehicle battery pack temperature pre-adjustment system.

[0100] It should be noted that the applicable scope of the technical solution of the present invention takes into account the general technical parameters and application scenarios of electric vehicles, that is, the heating power and refrigeration power are much smaller than the total vehicle power required for starting and normal driving. Therefore, even in the case of very low or very high temperatures, the battery pack cannot supply power to the whole vehicle normally, but it can still meet the heating and refrigeration power consumption; and the time-consuming for pre-adjusting the battery pack temperature is generally within 1 hour. Therefore, during the pre-adjustment process, it is approximately considered that the ambient temperature and wind speed remain unchanged.

[0101] Embodiment

[0102] Please refer to Figure 1 to understand three more specific embodiments.

[0103] Embodiment 1

[0104] This embodiment relates to a system for pre-adjusting the temperature of an electric vehicle battery pack. A lithium iron phosphate lithium-ion battery pack is provided on the chassis of an electric vehicle. An ambient temperature sensor and an ambient anemometer are provided on the lower surface of the electric vehicle chassis. The heating element is a PTC heater with a constant power P h = 10 kW, and the refrigeration element is an in-vehicle air conditioner with a constant power Pr = 8 kW. The peak power during the normal driving process after the vehicle starts is 200 kW. Among them, the PTC heating element is a PTC wire mesh coated on the battery shell and is directly used to heat the battery; while the refrigeration element exchanges heat with the coolant in the liquid cooling plate at the bottom of the battery pack through a heat exchanger, thereby indirectly cooling the battery pack. There are 3 battery pack temperature sensors at different positions in the battery pack, and their arithmetic mean value is output as the final battery pack temperature measurement value. The positioning element is a GPS chip, and the networking element is a 5G communication module. The controller electrically connected to the heating element, the refrigeration element, the battery pack temperature sensor, the ambient temperature sensor, the ambient anemometer, the positioning element and the networking element is integrated in the vehicle controller. The lower limit of the permitted operating temperature of the battery pack T min = 5 °C, and the upper limit of the permitted operating temperature T max = 45 °C, the average specific heat capacity c = 2000 J / (kg·°C), and the total mass m = 500 kg.

[0105] Embodiment 2

[0106] Based on Embodiment 1, this embodiment relates to a control method for the pre-adjusting system of the electric vehicle battery pack temperature in a cold environment.

[0107] An electric vehicle equipped with the electric vehicle battery pack temperature pre-adjustment system in Embodiment 1 parks at 18:00 on a certain day and shuts off the engine, then stops at an outdoor parking space. At 18:30, the vehicle owner reserves to use the vehicle at 08:00 the next morning through the smartphone APP. The controller then issues an instruction, measures the ambient air temperature T0 = 6°C and the ambient wind speed V0 = 2.5 m / s, and obtains the air temperature t0 = 5°C and the wind speed v0 = 2.0 m / s at 18:30 at the location of the electric vehicle provided by the weather forecast provider through the networking component.

[0108] If the controller obtains through the networking component the forecast air temperature t1 = 1°C and the forecast wind speed v1 = 3.0 m / s at 08:00 the next morning at the location of the electric vehicle provided by the weather forecast provider, then calculate the corrected air temperature t2 = t1 + T0 - t0 = 1 + 6 - 5 = 2°C <T min , and the corrected wind speed v2 = v1 + V0 - v0 = 3.0 + 2.5 - 2.0 = 3.5 m / s.

[0109] From the table of heat transfer ratio values between the battery pack and the environment at different wind speeds, it is found that at wind speeds of 3 m / s and 4 m / s, the heat transfer ratios between the battery pack and the environment are 1.5 kW / °C and 2.5 kW / °C respectively. Therefore, use linear interpolation to calculate the heat transfer ratio k corresponding to the corrected wind speed v2 = 3.5 m / s: k = 1.5 + (2.5 - 1.5) * (3.5 - 3) / (4 - 3) = 2.0 kW / °C.

[0110] Finally, calculate the time τ required for pre-adjusting the battery pack temperature:

[0111] τ = cm(T min - t2) / [P h - 0.5k(5 - 2)] = 2000 * 500 * (5 - 2) / [10000 - 0.5 * 2000 * (5 - 2)] ≈ 429 s

[0112] Therefore, at a moment 429 s before 08:00 the next morning, start heating the battery pack with a heating power of 10 kW until the temperature of the battery pack reaches the lower limit of the permitted operating temperature of 5°C.

[0113] Embodiment 3

[0114] Based on Embodiment 1, this embodiment relates to a control method of the electric vehicle battery pack temperature pre-adjustment system in a hot environment.

[0115] An electric vehicle equipped with the pre - regulation system for the temperature of the electric vehicle battery pack in Embodiment 1 parks at 8:00 on a certain day and shuts off the engine, then stops at an outdoor parking space. At 8:30, the vehicle owner reserves the vehicle for use at 14:00 through the smartphone APP. The controller then issues an instruction. It measures that the ambient air temperature \(T_0 = 43^{\circ}C\) and the ambient wind speed \(V_0 = 4.0m / s\). Through the networking component, it obtains the air temperature \(t_0 = 42^{\circ}C\) and the wind speed \(v_0 = 3.5m / s\) at the location of the electric vehicle given by the weather forecast provider at 8:30.

[0116] The controller obtains through the networking component the predicted air temperature \(t_1 = 49^{\circ}C\) and the predicted wind speed \(v_1 = 3.0m / s\) at the location of the electric vehicle at 14:00 given by the weather forecast provider. Then it calculates the corrected air temperature \(t_2=t_1 + T_0 - t_0=49 + 43 - 42 = 50^{\circ}C>T\) max , and the corrected wind speed \(v_2=v_1 + V_0 - v_0=3.0 + 4.0 - 3.5 = 3.5m / s\).

[0117] From the table of heat transfer ratio values between the battery pack and the environment at different wind speeds, it is found that at wind speeds of 3m / s and 4m / s, the heat transfer ratios between the battery pack and the environment are 1.5kW / °C and 2.5kW / °C respectively. Therefore, using linear interpolation, the heat transfer ratio \(k\) corresponding to the corrected wind speed \(v_2 = 3.5m / s\) is calculated as \(k = 1.5+(2.5 - 1.5)*(3.5 - 3) / (4 - 3)=2.0kW / °C\).

[0118] Finally, the time \(\tau\) required for pre - regulating the battery pack temperature is calculated:

[0119] \(\tau=\frac{cm(t_2 - T max )}{[P r -0.5k(t_2 - T max )]}=\frac{2000\times500\times(50 - 45)}{[8000 - 0.5\times2000\times(50 - 45)]}\approx

[0120] 1667s

[0121] Therefore, at a time 1667s before 14:00, start the refrigeration of the battery pack with a refrigeration power of 8kW until the temperature of the battery pack reaches the upper limit of the permitted operating temperature of \(45^{\circ}C\).

[0122] In the above - mentioned embodiment of the present invention, the influence of ambient air temperature and wind speed factors on the heat transfer of the battery pack is considered simultaneously. The weather forecast information is corrected by combining specific measured data, and the heat transfer ratio \(k\) values at different wind speeds are pre - calibrated. Therefore, the considered factors are comprehensive, scientific and reasonable. The pre - regulation logic of the battery pack is simple and easy to use, and it can accurately adjust the temperature of the battery pack at the reserved start - up time, having the advantages of high efficiency and energy saving.

Claims

1. A control method for a temperature pre-regulation system of an electric vehicle battery pack, which is used to adjust the temperature of an electric vehicle battery pack in a parked state to an appropriate range according to a time preset by the owner, characterized in that: The method is based on a temperature pre-regulation system for an electric vehicle battery pack, the system comprising a battery pack, a heating element, a cooling element, a battery pack temperature sensor, an ambient temperature sensor, an ambient anemometer, a positioning element and a networking element, wherein: The heating element and the cooling element are used to provide heating and cooling for the battery pack respectively; The battery pack temperature sensor is used to measure the battery pack temperature; The ambient temperature sensor and the ambient anemometer are used to measure the air temperature and wind speed of the external environment of the electric vehicle respectively; The positioning element is used to obtain the geographical location of the electric vehicle; The networking element is used for communication with the vehicle owner and for sending a query request to a weather forecast provider to obtain the temperature and wind speed information of the geographical location of the electric vehicle at a certain time; The method is that after the electric vehicle is parked, the owner makes an appointment with the electric vehicle for the next start time of the vehicle, and after the controller obtains the next start time of the vehicle, the following steps are performed in sequence: Step S1, measuring and obtaining the ambient temperature T0 and the ambient wind speed V0, and obtaining the temperature t0 and the wind speed v0 of the location of the electric vehicle at the measurement time provided by the weather forecast provider through the networking component; Step S2, obtaining the forecast temperature t1 and forecast wind speed v1 of the location of the electric vehicle at the next starting time provided by the weather forecast provider through the networking component; Step S3, calculating the corrected temperature t2 and the corrected wind speed v2 at the location of the electric vehicle at the next starting time: t2=t1+T0-t0 (1) v2=v1+V0-v0 (2) Step S4: Compare the corrected temperature t2 obtained in step S3 with the lower limit of the battery pack's permissible operating temperature T min And the upper limit of permissible operating temperature T max The size relationship between them: If T min ≤t2≤T max , then stop the execution of all subsequent steps, otherwise go to step S5; Step S5, calculating the battery pack temperature pre-adjustment time τ: If t2 <T min ,but: τ=cm(T min -t2) / [P h -0.5k(T min -t2)] (3) If t2>T max ,but: τ=cm(t2-T max ) / [P r -0.5k(t2-T max )] (4) The above t2 is the corrected temperature obtained in step S3, c and m are the average specific heat capacity and total mass of the battery pack, T min and T max are the lower and upper limits of the permissible operating temperature of the battery pack, respectively. h and P r are the heating power of the heating element and the cooling power of the cooling element, respectively, and k is the heat exchange ratio between the battery pack and the environment; The value of heat exchange ratio k is determined by the following method: The controller pre-stores a table of heat exchange ratio values ​​between the battery pack and the environment at different wind speeds; Based on the corrected wind speed v2 obtained in step S4, the two wind speed values ​​closest to it and their corresponding heat exchange ratio values ​​are found in the table; The heat exchange ratio value corresponding to the corrected wind speed v2 is obtained by using the linear interpolation calculation method, which is the value of the heat exchange ratio k; Step S6: At a time τ before the next start time, start pre-conditioning of the battery pack until the temperature of the battery pack is within the range of the lower limit and upper limit of the permissible operating temperature: If t2 <T min , the battery pack heating is started; if t2>T max , the battery pack cooling is started.

2. The control method of the electric vehicle battery pack temperature pre-regulation system according to claim 1, characterized in that: The heating element is a PTC heater, and the heating power is constant.

3. The control method of the electric vehicle battery pack temperature pre-regulation system according to claim 1, characterized in that: The refrigeration element is a vehicle-mounted air conditioner, and the refrigeration power is constant.

4. The control method of the electric vehicle battery pack temperature pre-regulation system according to claim 1, characterized in that: The positioning element is a satellite positioning chip.

5. The control method of the electric vehicle battery pack temperature pre-regulation system according to claim 1, characterized in that: The number of the battery pack temperature sensors is one or more. When the number of the battery pack temperature sensors is multiple, their arithmetic mean is taken as the final measurement value.

6. The control method of the electric vehicle battery pack temperature pre-regulation system according to claim 1, characterized in that: It also includes a controller, and the heating element, cooling element, battery pack temperature sensor, ambient temperature sensor, ambient anemometer, positioning element and networking element are all electrically connected to the controller.

7. The control method of the electric vehicle battery pack temperature pre-regulation system according to claim 1, characterized in that: The values ​​of the heat exchange ratios at different wind speeds in the heat exchange ratio value table are obtained by testing the following method before the vehicle leaves the factory: The electric vehicle is placed in a wind tunnel with constant wind temperature. The battery pack is heated or cooled at constant power at a series of different wind speeds until the battery pack temperature remains stable. The battery pack temperature is recorded and the heat exchange ratio value at the corresponding wind speed is obtained by dividing the heating or cooling power by the absolute value of the difference between the wind temperature and the battery pack temperature.

8. An electric vehicle, characterized in that: A control method for a temperature pre-regulation system for a battery pack of an electric vehicle is applied.

9. A computer-readable storage medium storing a plurality of control instructions, characterized in that: The control instruction is suitable for loading by a processor to execute the control method of the electric vehicle battery pack temperature pre-regulation system according to any one of claims 1 or 7.

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