A battery pack temperature control method and control system for electric vehicles

Abstract

The present invention relates to a battery pack temperature control method and control system for an electric vehicle, the control method comprising the following steps: an off-vehicle temperature control device obtains the state of the battery pack from a charging device, wherein the state of the battery pack includes a charging state; if the battery pack is in the charging state, the inlet temperature of the coolant entering the battery pack from the off-vehicle temperature control device is controlled to be a first target inlet temperature and the coolant flow rate is controlled to be a first preset flow rate; after the coolant is input into the battery pack for a first preset time, the first outlet temperature of the coolant is obtained; based on the first outlet temperature of the coolant and the target outlet temperature threshold of the coolant, the coolant flow rate and / or the coolant inlet temperature are controlled. The present invention provides a battery pack temperature control method for an electric vehicle, which uses an off-vehicle temperature control device to control the temperature of the battery pack of the electric vehicle, and the electric vehicle does not need to add an additional battery pack cooling system, thereby avoiding increasing the weight and cost of the electric vehicle.

Description

Technical Field

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

[0002] The promotion and application of new energy vehicles has received widespread attention and support worldwide, and the market share of electric vehicles has gradually increased. As the core component of electric vehicles, the temperature of the battery pack directly affects the performance and life of the electric vehicle. Therefore, the temperature control of the battery pack is very important.

[0003] In the prior art, for battery pack systems used in medium- and heavy-duty electric trucks and other vehicles, on-board water cooling units are mostly used to cool the battery packs. Among them, the cooling demand is the greatest when the battery pack is charging. With the advancement of battery technology and the increase in user requirements for charging time, the charging speed of the battery pack is getting faster and faster, gradually developing from the current 1C charging rate to 2C charging rate and above. According to the formula of heat generation power: P = I²R, under the same amount of electricity, the internal resistance does not change much, the required cooling power is greatly increased, and the power of the water cooling unit is increased. Under the limitation of the performance parameters of the existing water cooling unit, the number of water cooling units needs to be doubled, resulting in an increase in the cost and weight of a single vehicle, and causing trouble for the layout of the entire vehicle. Summary of the invention

[0004] The first aspect of the present invention provides a battery pack temperature control method for an electric vehicle, which is used to solve the technical problem that in the prior art, a vehicle-mounted water cooling unit is usually used to cool the power battery. When the power of the water cooling unit is increased, the number of water cooling units needs to be increased, resulting in an increase in the cost and weight of a single vehicle.

[0005] The present invention provides a method for controlling the temperature of a battery pack of an electric vehicle, wherein the battery pack is connected to an external temperature control device and a charging device respectively, and the temperature of the battery pack is controlled by the external temperature control device; the control method comprises the following steps:

[0006] The vehicle exterior temperature control device acquires the state of the battery pack from the charging device, wherein the state of the battery pack includes a charging state;

[0007] The vehicle exterior temperature control device determines whether the battery pack is in the charging state, and if so, controls the coolant inlet temperature entering the battery pack from the vehicle exterior temperature control device to be a first target inlet temperature and the coolant flow rate to be a first preset flow rate;

[0008] After the coolant is input into the battery pack for a first preset time, obtaining a first outlet temperature of the coolant;

[0009] The coolant flow rate and / or the coolant inlet temperature are controlled based on the coolant first outlet temperature and the coolant target outlet temperature threshold.

[0010] The present invention provides a method for controlling the temperature of a battery pack of an electric vehicle. On the one hand, the battery pack generates heat during charging, and an off-vehicle temperature control device is used to control the temperature of the battery pack of the electric vehicle. The electric vehicle does not need to add an additional battery pack cooling system, thereby avoiding increasing the weight and cost of the electric vehicle and reducing the energy consumption of the electric vehicle during operation. On the other hand, based on the first outlet temperature of the coolant and the target outlet temperature threshold of the coolant, the parameters of the coolant - the coolant flow rate and / or the coolant inlet temperature - are controlled. During charging, the battery pack does not interact with the off-vehicle temperature control device, and the temperature of the battery pack of the electric vehicle is controlled. There is no need to add software and hardware for interaction between the electric vehicle and the battery pack, thereby improving the applicability and convenience of the off-vehicle temperature control device to the electric vehicle and saving costs.

[0011] Optionally, the step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold comprises:

[0012] Determine whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold, and if so, increase the coolant flow rate and / or reduce the coolant inlet temperature;

[0013] Determine whether the first coolant outlet temperature is less than a minimum coolant target outlet temperature threshold value; if so, reduce the coolant flow rate and / or increase the coolant inlet temperature.

[0014] In this way, the first outlet temperature of the coolant is compared with the target outlet temperature threshold of the coolant. If the first outlet temperature of the coolant is greater than the maximum value of the target outlet temperature threshold of the coolant, it indicates that the temperature of the battery pack is too high and needs further cooling treatment. The cooling capacity of the battery pack is increased by increasing the coolant flow rate and / or lowering the coolant inlet temperature, so that the first outlet temperature of the coolant is reduced and falls within the range of the target outlet temperature threshold of the coolant. If the first outlet temperature of the coolant is less than the minimum value of the target outlet temperature threshold of the coolant, the coolant flow rate is reduced and / or the coolant inlet temperature is increased, indicating that the temperature of the battery pack is too low and needs further heating treatment, so that the first outlet temperature of the coolant is increased and falls within the range of the target outlet temperature threshold of the coolant.

[0015] Optionally, it is determined whether the first outlet temperature of the coolant falls within the coolant target outlet temperature threshold range, and if so, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack. This setting indicates that the temperature of the battery pack is within a normal range, and the first target inlet temperature and the first preset flow rate do not need to be adjusted.

[0016] Optionally, after the step of determining whether the first coolant outlet temperature falls within the coolant target outlet temperature threshold range, and if so, maintaining the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack, the control method further includes:

[0017] Determine whether the difference between the maximum value of the coolant target outlet temperature threshold and the coolant first outlet temperature is greater than a preset difference; if so, maintain the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack; otherwise,

[0018] The vehicle exterior temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging current. If the rate of change of the charging current within a second preset time period is greater than zero, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging current within the second preset time period is not greater than zero, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack. With this configuration, the coolant target outlet temperature threshold is further divided. If the difference between the maximum value of the coolant target outlet temperature threshold and the first coolant outlet temperature is less than or equal to the preset difference, the rate of change of the charging current is introduced to control the battery pack. The heat generation is predicted. If the rate of change of the charging current is greater than zero, it indicates that the heat generation of the battery pack has increased and cooling needs to be increased. By increasing the coolant flow rate and / or reducing the coolant inlet temperature in advance, the temperature of the battery pack can be precisely controlled. Or, the vehicle temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging power. If the rate of change of the charging power is greater than zero within the second preset time, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging power is not greater than zero within the second preset time, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack. In this way, the coolant target outlet temperature threshold is further divided. If the difference between the maximum value of the coolant target outlet temperature threshold and the first coolant outlet temperature is less than or equal to the preset difference, the rate of change of the charging current is introduced to predict the heat generation of the battery pack. If the rate of change of the charging current is greater than zero, it indicates that the heat generation of the battery pack has increased and cooling needs to be increased. By increasing the coolant flow rate and / or reducing the coolant inlet temperature in advance, the temperature of the battery pack can be precisely controlled. With this setting, the coolant target outlet temperature threshold is further divided. If the difference between the maximum value of the coolant target outlet temperature threshold and the first coolant outlet temperature is less than or equal to the preset difference, the charging power change rate is introduced to predict the heat generation of the battery pack. If the charging power change rate is greater than zero, it indicates that the heat generation of the battery pack has increased and cooling needs to be increased. The battery pack temperature can be accurately controlled by increasing the coolant flow rate and / or lowering the coolant inlet temperature in advance.

[0019] Optionally, the step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold further includes:

[0020] Determine whether the first outlet temperature of the coolant falls within the coolant target outlet temperature threshold range, and if so, determine whether the difference between the maximum value of the coolant target outlet temperature threshold and the first outlet temperature of the coolant is greater than a preset difference, and if so, maintain the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack; otherwise,

[0021] The external temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging current. If the rate of change of the charging current within a second preset time period is greater than zero, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging current within the second preset time period is not greater than zero, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack; or, the external temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging power. If the rate of change of the charging power within the second preset time period is greater than zero, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging power within the second preset time period is not greater than zero, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack.

[0022] Optionally, the step of increasing the coolant flow rate and / or reducing the coolant inlet temperature comprises:

[0023] Determine whether the first coolant outlet temperature is on an upward trend; if so, increase the coolant flow rate to obtain a first coolant flow rate, and / or reduce the coolant inlet temperature to obtain a first coolant inlet temperature;

[0024] The first coolant flow rate satisfies the formula:

[0025]

[0026] in, Q 0 is the first preset flow rate of coolant per unit time; Q v1 is the first coolant flow rate per unit time; T N is the first outlet temperature of the coolant at the Nth moment; T N-1 is the first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k v1 is the first variation coefficient of coolant flow rate; ɑ 1 is a conversion coefficient greater than 0; and / or, the first coolant inlet temperature satisfies the following formula:

[0027]

[0028] in, T 0 is the first target inlet temperature; T 1 is the first coolant inlet temperature; T N is the first outlet temperature of the coolant at the Nth moment; T N-1 The first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k T1 is the first variation coefficient of the coolant inlet temperature; β 1 is a conversion coefficient greater than 0. In this way, the first change coefficient of the coolant flow rate is obtained based on the change rate of the first coolant outlet temperature, and then the first coolant flow rate per unit time is obtained; the first change coefficient of the coolant inlet temperature is obtained based on the change rate of the first coolant outlet temperature, and then the first coolant inlet temperature per unit time is obtained.

[0029] Optionally, the step of reducing the coolant flow rate and / or increasing the coolant inlet temperature comprises:

[0030] Determine whether the first coolant outlet temperature is on a downward trend; if so, reduce the coolant flow rate to obtain a second coolant flow rate, and / or increase the coolant inlet temperature to obtain a second coolant inlet temperature;

[0031] The second coolant flow rate satisfies the formula:

[0032]

[0033] in, Q 0 is the first preset flow rate of coolant per unit time; Q v2 is the second coolant flow rate; T N is the first outlet temperature of the coolant at the Nth moment; T N-1 The first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T Coolant first outlet temperature change rate value; k v2The second variation coefficient of coolant flow rate; ɑ 2 is a conversion coefficient greater than 0; and / or, the second coolant inlet temperature satisfies the following formula:

[0034]

[0035] in, T 0 is the first target inlet temperature; T 2 is the second coolant inlet temperature; T N is the first outlet temperature of the coolant at the Nth moment; T N-1 The first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k T2 is the second variation coefficient of coolant inlet temperature; β 2 is a conversion coefficient greater than 0. In this way, based on the change rate of the first coolant outlet temperature, the second change coefficient of the coolant flow rate is obtained, and then the second coolant flow rate per unit time is obtained; based on the change rate of the first coolant outlet temperature, the second change coefficient of the coolant inlet temperature is obtained, and then the second coolant inlet temperature per unit time is obtained.

[0036] Optionally, the state of the battery pack also includes a state before charging;

[0037] The control method further includes: determining whether the battery pack is in the pre-charging state, and if so, controlling the coolant inlet temperature entering the battery pack from the vehicle exterior temperature control device to be a first preset inlet temperature and the coolant flow rate to be a second preset flow rate;

[0038] After the coolant is input into the battery pack for a third preset time, detecting a third outlet temperature of the coolant;

[0039] Calculating an initial temperature of the battery pack based on the first preset inlet temperature and the third outlet temperature of the coolant;

[0040] The first target inlet temperature and the first preset flow rate are determined based on an initial temperature of the battery pack.

[0041] With such an arrangement, when the battery pack is in a state before charging, the initial temperature of the battery pack is estimated in advance based on the first preset inlet temperature and the third outlet temperature of the coolant, and the first target inlet temperature and the first preset flow rate of the coolant input into the battery pack are determined based on the initial temperature of the battery pack. On the one hand, the temperature regulation efficiency of the battery pack is improved; on the other hand, the temperature control requirements of the battery pack when entering the charging state are better met; in addition, the outdoor temperature control device does not interact with the battery pack of the electric vehicle, and the temperature of the battery pack of the electric vehicle is controlled without adding software and hardware for the interaction between the electric vehicle and the battery pack, which improves the applicability and ease of use of the outdoor temperature control device for electric vehicles, and also saves costs.

[0042] Optionally, the step of determining the first target inlet temperature and the first preset flow rate based on the initial temperature of the battery pack includes:

[0043] Obtaining a preset battery pack temperature threshold, wherein the battery pack temperature threshold includes at least one temperature interval, and each temperature interval is provided with a corresponding coolant inlet temperature and coolant flow rate;

[0044] Determining the temperature interval in which the initial temperature of the battery pack is located;

[0045] The coolant inlet temperature corresponding to the temperature range is determined as the first target inlet temperature; and the coolant flow rate corresponding to the temperature range is determined as the first preset flow rate. In this way, the battery pack temperature threshold is divided into temperature zones, and different coolant flows and / or different coolant inlet temperatures are adopted for the initial temperature of the battery pack in different temperature ranges, so as to respond to the cooling demand of the battery pack more quickly.

[0046] Optionally, the initial temperature of the battery pack satisfies the formula:

[0047]

[0048] in, T B is the initial temperature of the battery pack; C is the volume heat capacity of the coolant; Q v is the coolant flow rate per unit time; h is the surface convection heat transfer coefficient; A The wall area that the coolant passes through when flowing through the internal flow channel of the battery pack per unit time; t The time it takes for the coolant to flow out of the internal flow channel of the battery pack; T in is a first preset inlet temperature; T out is the third outlet temperature of the coolant.

[0049] Optionally, the step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold comprises:

[0050] Determine whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold value. If so, the vehicle exterior temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging current. Determine whether the charging current increases to a preset maximum current value and then begins to decrease within a fourth preset time period, and the absolute value of the charging current decrease rate is greater than or equal to the first preset current rate value. If so, increase the coolant flow rate and / or reduce the coolant inlet temperature.

[0051] Or, determine whether the first outlet temperature of the coolant is greater than the maximum value of the coolant target outlet temperature threshold. If so, the external temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging power; determine whether the charging power increases to a preset maximum power value within a fourth preset time period and then begins to decrease, and the absolute value of the charging power reduction rate is greater than or equal to the first preset power rate value. If so, increase the coolant flow rate and / or reduce the coolant inlet temperature.

[0052] Optionally, the step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold comprises:

[0053] Determine whether the first coolant outlet temperature is less than the minimum value of the coolant target outlet temperature threshold value, and if so, the vehicle exterior temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging current; Determine whether the charging current is greater than or equal to the first preset current value and starts to decrease after continuing for a fifth preset time, and the absolute value of the charging current decrease rate is less than or equal to the second preset current rate value, and if so, reduce the coolant flow or stop the coolant input to the battery pack;

[0054] Or, determine whether the first outlet temperature of the coolant is less than the minimum value of the coolant target outlet temperature threshold. If so, the vehicle external temperature control device obtains the charging parameters of the battery pack from the charging device, and the charging parameters include the rate of change of the charging power; determine whether the charging power is greater than or equal to the first preset power value and starts to decrease after continuing for the fifth preset time, and the absolute value of the charging power reduction rate is less than or equal to the second preset power rate value. If so, reduce the coolant flow rate or stop the coolant input into the battery pack.

[0055] A second aspect of the present invention provides a battery pack temperature control system for an electric vehicle, which is applied to any of the above-mentioned battery pack temperature control methods for an electric vehicle, and the control system comprises:

[0056] an acquisition unit, configured to acquire the first target inlet temperature, the first outlet temperature of the coolant, and the state of the battery pack from the charging device; wherein the state of the battery pack includes a charging state;

[0057] A judging unit, used for judging whether the battery pack is in the charging state;

[0058] A control unit is used to control the coolant inlet temperature entering the battery pack to be a first target inlet temperature and the coolant flow rate to be a first preset flow rate when the battery pack is in the charging state; and to control the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold.

[0059] An embodiment of the present invention provides a battery pack temperature control system for an electric vehicle. On the one hand, the battery pack generates heat during charging, and the temperature of the battery pack of the electric vehicle is controlled by using an external temperature control device. The electric vehicle does not need to add an additional battery pack cooling system, thereby avoiding increasing the weight and cost of the electric vehicle and reducing the energy consumption of the electric vehicle during operation. On the other hand, based on the first outlet temperature of the coolant and the target outlet temperature threshold of the coolant, the coolant flow rate and / or the coolant inlet temperature are controlled. During charging, the battery pack does not exchange information with the external temperature control device of the electric vehicle, and the temperature of the battery pack of the electric vehicle is controlled. There is no need to add software or hardware for interaction between the electric vehicle and the battery pack, thereby improving the applicability and convenience of the external temperature control device to the electric vehicle and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 A schematic diagram of the connection status between a battery pack, an external temperature control device and a charging device during a battery pack charging process corresponding to a battery pack temperature control method for an electric vehicle provided in an embodiment of the present invention;

[0061] Figure 2 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 1 ;

[0062] Figure 3 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 2 ;

[0063] Figure 4A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 3 ;

[0064] Figure 5 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 4 ;

[0065] Figure 6 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 5 ;

[0066] Figure 7 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 6 ;

[0067] Figure 8 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 7 ;

[0068] Fig. 9 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 8 ;

[0069] Fig.10 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 9 ;

[0070] Fig.11 A flow chart of a method for controlling the temperature of a battery pack of an electric vehicle provided by an embodiment of the present invention Figure 10 ;

[0071] Fig.12 A schematic diagram of a battery pack temperature control system for an electric vehicle provided in an embodiment of the present invention.

[0072] Description of reference numerals:

[0073] 1. Battery pack; 2. External temperature control device; 3. Charging device; 4. First temperature sensor; 5. Second temperature sensor; 10. Acquisition unit; 20. Judgment unit; 30. Control unit. DETAILED DESCRIPTION

[0074] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the following is a brief description of the present invention in conjunction with the attached drawings. Figure 1 —12 A detailed description of the specific embodiments of the present invention is given.

[0075] The present invention controls the temperature of the battery pack 1, which may be cooling control of the battery pack 1 or heating control of the battery pack 1. In the embodiment of the present invention, cooling control of the battery pack 1 is taken as an example.

[0076] See attached Figure 1 and Figure 2 A first aspect of an embodiment of the present invention provides a method for controlling the temperature of a battery pack of an electric vehicle, wherein a battery pack 1 is connected to an external temperature control device 2 and a charging device 3, respectively, and the temperature of the battery pack 1 is controlled by the external temperature control device 2; the control method comprises the following steps:

[0077] S100, the vehicle exterior temperature control device 2 obtains the status of the battery pack from the charging device 3, wherein the status of the battery pack includes a charging status;

[0078] S200, determining whether the vehicle exterior temperature control device 2 determines whether the battery pack 1 is in a charging state, and if so, controlling the coolant inlet temperature entering the battery pack 1 from the vehicle exterior temperature control device 2 to be a first target inlet temperature and the coolant flow rate to be a first preset flow rate;

[0079] S300, after the coolant is input into the battery pack 1 for a first preset time, a first outlet temperature of the coolant is obtained;

[0080] S400, based on the first coolant outlet temperature and the coolant target outlet temperature threshold, control the coolant flow, or control the coolant inlet temperature, or control the coolant flow and the coolant inlet temperature at the same time. Compared with controlling the coolant flow or the coolant inlet temperature alone, controlling the coolant flow and the coolant inlet temperature at the same time can more quickly meet the current cooling demand, and on the other hand, can also avoid damage to the cooling circuit inside the battery due to excessive pressure in the cooling line caused by excessive coolant flow.

[0081] It should be noted that the first target inlet temperature is a preset inlet temperature, which can be adjusted based on the first outlet temperature of the coolant; the first preset flow rate is the flow rate of the coolant per unit time controlled by the water pump.

[0082] An embodiment of the present invention provides a method for controlling the temperature of a battery pack of an electric vehicle. On the one hand, the battery pack 1 will generate heat during the charging process. The temperature of the battery pack 1 of the electric vehicle is controlled by an external temperature control device 2. The electric vehicle does not need to add an additional cooling system for the battery pack 1, thereby avoiding increasing the weight and cost of the electric vehicle and reducing the energy consumption of the electric vehicle during operation. On the other hand, based on the first outlet temperature of the coolant and the target outlet temperature threshold of the coolant, the coolant flow rate and / or the coolant inlet temperature are controlled. During the charging process of the battery pack 1, the external temperature control device 2 does not interact with the battery pack 1 of the electric vehicle. The temperature of the battery pack 1 of the electric vehicle is controlled, and there is no need to add software and hardware for interaction between the electric vehicle and the battery pack 1, thereby improving the applicability and convenience of the external temperature control device 2 to the electric vehicle and also saving costs.

[0083] See attached Figure 1 An inlet pipe and an outlet pipe are connected between the external temperature control device 2 and the battery pack 1. The inlet pipe is provided with a first temperature sensor 4 for detecting the inlet temperature of the coolant; the outlet pipe is provided with a second temperature sensor 5 for detecting the first outlet temperature of the coolant and / or the third outlet temperature of the coolant. The external temperature control device 2 is electrically connected to the charging device 3, and the external temperature control device 2 obtains the state of the battery pack from the charging device 3. The charging device 3 is electrically connected to the battery pack 1, and is used to charge the battery pack 1.

[0084] The embodiments of the present invention are shown in the attached Figure 3 , step S400 includes:

[0085] S410, determine whether the first outlet temperature of the coolant is greater than the maximum value of the coolant target outlet temperature threshold. If so, increase the coolant flow rate, or reduce the coolant inlet temperature, or increase the coolant flow rate and reduce the coolant inlet temperature at the same time. In this way, the first outlet temperature of the coolant is compared with the coolant target outlet temperature threshold. If the first outlet temperature of the coolant is greater than the maximum value of the coolant target outlet temperature threshold, it indicates that the temperature of the battery pack 1 is too high and needs further cooling. Then, by increasing the coolant flow rate and / or reducing the coolant inlet temperature, the cooling capacity of the battery pack 1 is increased, so that the first outlet temperature of the coolant is reduced and falls within the coolant target outlet temperature threshold.

[0086] S420, determine whether the first outlet temperature of the coolant is less than the minimum value of the coolant target outlet temperature threshold. If so, reduce the coolant flow rate, or increase the coolant inlet temperature, or reduce the coolant flow rate and increase the coolant inlet temperature. In this way, the first outlet temperature of the coolant is compared with the coolant target outlet temperature threshold. If the first outlet temperature of the coolant is less than the minimum value of the coolant target outlet temperature threshold, then by reducing the coolant flow rate and / or increasing the coolant inlet temperature, it is indicated that the temperature of the battery pack 1 is too low and further heating treatment is required, so that the first outlet temperature of the coolant is increased and falls within the coolant target outlet temperature threshold.

[0087] The order of S410 and S420 is not limited here.

[0088] The embodiments of the present invention are shown in the attached Figure 3 , step S400 further includes:

[0089] S430, determining whether the first outlet temperature of the coolant falls within the target outlet temperature threshold range of the coolant, and if so, maintaining the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack 1. This setting indicates that the temperature of the battery pack 1 is within the normal range, and the first target inlet temperature and the first preset flow rate do not need to be adjusted.

[0090] S440, determine whether the difference between the maximum value of the coolant target outlet temperature threshold and the first coolant outlet temperature is greater than the preset difference. If so, maintain the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack 1; otherwise, execute step S460, wherein step S460 can be implemented in multiple ways, and the coolant inlet temperature and / or coolant flow rate can be controlled based on the charging parameters of the battery pack, such as the rate of change of the charging current or the rate of change of the charging power.

[0091] See attached Figure 3 In one implementation, step S460 includes the following steps:

[0092] S461, the vehicle exterior temperature control device 2 obtains charging parameters of the battery pack from the charging device 3, where the charging parameters include a rate of change of the charging current;

[0093] S462, if the rate of change of the charging current within the second preset time period is greater than zero, increasing the coolant flow rate, or reducing the coolant inlet temperature, or increasing the coolant flow rate and reducing the coolant inlet temperature at the same time;

[0094] S463, if the rate of change of the charging current within the second preset time is not greater than zero, then maintain the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack 1. With this setting, the coolant target outlet temperature threshold is further divided. If the difference between the maximum value of the coolant target outlet temperature threshold and the first outlet temperature of the coolant is less than or equal to the preset difference, the rate of change of the charging current is introduced to predict the heat generation of the battery pack 1. If the rate of change of the charging current is greater than zero, it indicates that the heat generation of the battery pack 1 has increased and cooling needs to be increased. By increasing the coolant flow rate and / or reducing the coolant inlet temperature in advance, the temperature of the battery pack 1 can be accurately controlled.

[0095] In a specific implementation of the embodiment of the present invention, if the rate of change of the charging current within the second preset time period is 0.05 ( ); the corresponding coolant flow rate increases by a coefficient of 0.05, or the coolant inlet temperature increases by 2 ( ) decreases, or the coolant flow rate increases by a factor of 0.05 while the coolant inlet temperature increases by a factor of 1 ( ) decreases in rate of change.

[0096] See attached Figure 3 In another implementation, step S460 includes the following steps:

[0097] S464, the vehicle exterior temperature control device 2 obtains charging parameters of the battery pack from the charging device 3, where the charging parameters include a rate of change of the charging power;

[0098] S465, if the rate of change of the charging power within the second preset time period is greater than zero, increasing the coolant flow rate, or reducing the coolant inlet temperature, or increasing the coolant flow rate and reducing the coolant inlet temperature at the same time;

[0099] S466, if the rate of change of the charging power within the second preset time is not greater than zero, then maintain the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack 1. With this setting, the coolant target outlet temperature threshold is further divided. If the difference between the maximum value of the coolant target outlet temperature threshold and the first outlet temperature of the coolant is less than or equal to the preset difference, the rate of change of the charging power is introduced to predict the heat generation of the battery pack 1. If the rate of change of the charging power is greater than zero, it indicates that the heat generation of the battery pack 1 has increased and cooling needs to be increased. By increasing the coolant flow rate and / or reducing the coolant inlet temperature in advance, the temperature of the battery pack 1 can be accurately controlled.

[0100] In a specific implementation of the embodiment of the present invention, if the rate of change of the charging power within the second preset time period is 0.05 ( ); the corresponding coolant flow rate increases by a coefficient of 0.05, or the coolant inlet temperature increases by 2 ( ) decreases, or the coolant flow rate increases by a factor of 0.05 while the coolant inlet temperature increases by a factor of 2 ( ) decreases in rate of change.

[0101] Step S410 can be implemented in a variety of ways. The coolant flow rate and / or the coolant inlet temperature can be controlled based on the first coolant outlet temperature; the coolant flow rate and / or the coolant inlet temperature can be controlled based on the rate of change of the charging current; the coolant flow rate and / or the coolant inlet temperature can be controlled based on the rate of change of the charging power.

[0102] The embodiments of the present invention are shown in the attached Figure 4 In one embodiment, based on the first outlet temperature of the coolant, the coolant flow rate and / or the coolant inlet temperature are controlled, and step S410 specifically includes:

[0103] Determine whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold, and whether the first coolant outlet temperature shows an upward trend; if so, increase the coolant flow rate to obtain the first coolant flow rate, or reduce the coolant inlet temperature to obtain the first coolant inlet temperature, or simultaneously increase the coolant flow rate and reduce the coolant inlet temperature to obtain the first coolant flow rate and the first coolant inlet temperature respectively.

[0104] The first coolant flow rate satisfies the formula:

[0105]

[0106] in, Q 0 is the first preset flow rate of coolant per unit time, in units of ; Q v1 is the first coolant flow rate per unit time, in units of ; k v1 is the first variation coefficient of coolant flow rate; T N is the first outlet temperature of the coolant at the Nth moment, in units of K ; T N-1 is the first outlet temperature of the coolant at the N-1th moment, in units of K ; Δt is the time difference between the Nth moment and the N-1th moment, in units of s ; k T is the change rate of the first outlet temperature of the coolant; ɑ1 is a conversion coefficient greater than 0. In this way, based on the change rate of the first outlet temperature of the coolant, the first change coefficient of the coolant flow rate is obtained, and then the first coolant flow rate per unit time is obtained.

[0107] If the first outlet temperature of the coolant is detected to be high in the previous period, the coolant flow rate in the next period is adjusted to increase, so that the coolant flow rate flowing into the battery pack 1 per unit time increases, thereby increasing the heat exchange amount per unit time. k T =1, ɑ When 1=0.05, the first change coefficient of coolant flow k v1 =0.05.

[0108] The first coolant inlet temperature satisfies the following formula:

[0109]

[0110] in, T 0 is the first target inlet temperature, in units of K ; T 1 is the first coolant inlet temperature, in units of K ; T N is the first outlet temperature of the coolant at the Nth moment, in units of K ; T N-1 The first outlet temperature of the coolant at the N-1th moment, in units of K ; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k T1 is the first variation coefficient of the coolant inlet temperature; β 1 is a conversion coefficient greater than 0. In this way, based on the change rate of the first coolant outlet temperature, the first change coefficient of the coolant inlet temperature is obtained, and then the first coolant inlet temperature per unit time is obtained.

[0111] If the first outlet temperature of the coolant is detected to be high in the previous period, the inlet temperature of the coolant in the next period is reduced, and the heat exchange amount per unit time is increased to ensure that the first outlet temperature of the coolant in the next period falls within the coolant target outlet temperature threshold range. k T =1, β When 1=2, the first change coefficient of coolant inlet temperature k T1 =2.

[0112] Step S420 can be implemented in a variety of ways. The coolant flow rate and / or the coolant inlet temperature can be controlled based on the first coolant outlet temperature; the coolant flow rate and / or the coolant inlet temperature can be controlled based on the rate of change of the charging current; the coolant flow rate and / or the coolant inlet temperature can be controlled based on the rate of change of the charging power.

[0113] The embodiments of the present invention are shown in the attached Figure 5 In one embodiment, based on the first outlet temperature of the coolant, the coolant flow rate and / or the coolant inlet temperature are controlled, and step S420 specifically includes:

[0114] Determine whether the first coolant outlet temperature is less than the minimum value of the coolant target outlet temperature threshold, and determine whether the first coolant outlet temperature is on a downward trend; if so, reduce the coolant flow rate to obtain a second coolant flow rate, or increase the coolant inlet temperature to obtain a second coolant inlet temperature, or simultaneously reduce the coolant flow rate and increase the coolant inlet temperature to obtain the second coolant flow rate and the second coolant inlet temperature respectively.

[0115] The second coolant flow rate satisfies the formula:

[0116]

[0117] in, Q 0 is the first preset flow rate of coolant per unit time, in units of ; Q v2 is the second coolant flow rate, in units of ; T N is the first outlet temperature of the coolant at the Nth moment, in units of K ; T N-1 The first outlet temperature of the coolant at the N-1th moment, in units of K ; Δt is the time difference between the Nth moment and the N-1th moment, in units of s ; k T is the change rate of the first outlet temperature of the coolant; k v2 is the second variation coefficient of coolant flow rate; ɑ 2 is a conversion coefficient greater than 0. In this way, based on the change rate of the first outlet temperature of the coolant, the second change coefficient of the coolant flow rate is obtained, and then the second coolant flow rate per unit time is obtained.

[0118] If the first outlet temperature of the coolant is detected to be low in the previous period, the coolant flow rate in the next period is adjusted to reduce the coolant flow rate flowing into the battery pack 1 per unit time, thereby reducing the heat exchange amount per unit time. k T = -1, ɑ 2 = 0.05, the second change coefficient of coolant flow k v2 =-0.05.

[0119] The second coolant inlet temperature satisfies the following formula:

[0120]

[0121] in, T 0 is the first target inlet temperature, in units of K ; T 2 is the second coolant inlet temperature, unit K ; T N is the first outlet temperature of the coolant at the Nth moment, in units of K ; T N-1 is the first outlet temperature of the coolant at the N-1th moment, in units of K ; Δt is the time difference between the Nth moment and the N-1th moment, in units of s ; k T is the change rate of the first outlet temperature of the coolant; k T2 is the second variation coefficient of coolant inlet temperature; β 2 is a conversion coefficient greater than 0. In this way, based on the change rate of the first coolant outlet temperature, the second change coefficient of the coolant inlet temperature is obtained, and then the second coolant inlet temperature per unit time is obtained.

[0122] If the first outlet temperature of the coolant in the previous period is detected to be low, the inlet temperature of the coolant in the next period is adjusted to increase so that the temperature of the coolant flowing into the battery pack 1 per unit time is reduced, thereby reducing the heat exchange amount per unit time to ensure that the first outlet temperature of the coolant in the next period falls within the target outlet temperature threshold range of the coolant. For example, when the first outlet temperature change rate value of the coolant is k T = -1, β When 2=2, the second coefficient of change of coolant inlet temperature k T2 =-2.

[0123] In the embodiment of the present invention, the state of the battery pack also includes the state before charging, see the attached Figure 6 , the control method further comprises the following steps:

[0124] S101, the vehicle exterior temperature control device 2 determines whether the battery pack 1 is in a pre-charging state, and if so, controls the inlet temperature of the coolant entering the battery pack 1 from the vehicle exterior temperature control device 2 to be a first preset inlet temperature and the coolant flow rate to be a second preset flow rate;

[0125] S102, after the coolant is input into the battery pack 1 for a third preset time, a third outlet temperature of the coolant is detected;

[0126] S103, calculating an initial temperature of the battery pack based on the first preset inlet temperature and the third outlet temperature of the coolant;

[0127] S104, determining a first target inlet temperature and a first preset flow rate based on the initial temperature of the battery pack.

[0128] With such configuration, when the battery pack 1 is in a pre-charging state, the initial temperature of the battery pack is estimated in advance based on the first preset inlet temperature and the third outlet temperature of the coolant, and the first target inlet temperature and the first preset flow rate of the coolant input into the battery pack 1 are determined based on the initial temperature of the battery pack. On the one hand, the temperature regulation efficiency of the battery pack 1 is improved; on the other hand, the temperature control requirement of the battery pack 1 when entering the charging state is better met; in addition, the outdoor temperature control device 2 does not interact with the battery pack 1 of the electric vehicle, and the temperature of the battery pack 1 of the electric vehicle is controlled, and there is no need to increase the software and hardware for the interaction between the electric vehicle and the battery pack 1, which improves the applicability and convenience of the outdoor temperature control device 2 to the electric vehicle, and also saves costs.

[0129] The embodiments of the present invention are shown in the attached Figure 7 , step S103 specifically includes:

[0130] S1031, obtaining a preset battery pack temperature threshold, wherein the battery pack temperature threshold includes at least one temperature interval, and each temperature interval is provided with a corresponding coolant inlet temperature and coolant flow rate;

[0131] S1032, determining a temperature range in which the initial temperature of the battery pack is located;

[0132] S1033, determining the corresponding coolant inlet temperature as the first target inlet temperature according to the temperature interval; and determining the corresponding coolant flow rate as the first preset flow rate according to the temperature interval. In this way, the battery pack temperature threshold is divided into temperature zones, and different coolant flows and / or different coolant inlet temperatures are adopted for the initial temperature of the battery pack in different temperature intervals, so as to respond to the cooling demand of the battery pack 1 more quickly.

[0133] For example, the preset battery pack temperature threshold is [0°C, 35°C], and the preset battery pack temperature threshold is divided into 5°C intervals to obtain multiple temperature intervals, each temperature interval has a corresponding coolant inlet temperature and coolant flow rate, the preset battery pack 1 temperature is negatively correlated with the coolant inlet temperature, and the preset battery pack 1 temperature is positively correlated with the coolant flow rate. Referring to Table 1, the coolant inlet temperature satisfies: T1>T2>T3>T4>T5>T6; the coolant flow rate satisfies: Q1<Q2<Q3<Q4<Q5<Q6.

[0134] Table 1 Correspondence between temperature range, coolant inlet temperature and coolant flow rate

[0135]

[0136] In the embodiment of the present invention, in step S103, the formula for the initial temperature of the battery pack is:

[0137] (1-1)

[0138] The above formula (1-1) is obtained from formulas (1-2)-(1-6), which are as follows:

[0139] (1-2)

[0140] (1-3)

[0141] (1-4)

[0142] (1-5)

[0143] (1-6)

[0144] in, W is the area per unit time A The heat transfer quantity on ; t The time for the coolant to flow out of the internal flow channel of the battery pack 1, in units of s ; E for t The amount of heat absorbed by the coolant in a given period of time, in units of J ; h is the surface convection heat transfer coefficient, in units of ; is the wall area that the coolant passes through when flowing through the internal flow channel of the battery pack per unit time, in units of ; Related to the cross-sectional shape of the flow channel. For example, for a cylindrical flow channel, assuming that the cross-sectional shape of the flow channel is the same, ,r is the radius of the cylindrical flow channel, in units of m ; L The length of the coolant flowing through the cylindrical channel per unit time, in units of ; is the initial temperature of the battery pack, in K ; is the first preset inlet temperature, in units of K ; W 液 is the heat absorbed by the coolant per unit time, in units of ; C is the volume heat capacity of the coolant, in units of ; v is the coolant flow rate per unit time, in units ; is the third outlet temperature of the coolant, in units of K .

[0145] It can be seen from the above formula that based on the first preset inlet temperature and coolant third outlet temperature , the initial temperature of the battery pack can be estimated ; Initial temperature of the battery pack and the first preset inlet temperature Under the condition of no change, the coolant flow rate per unit time v and Inversely proportional, that is, the coolant flow rate per unit time v The bigger, The smaller the difference, that is, the coolant third outlet temperature The smaller.

[0146] The embodiments of the present invention are shown in the attached Figure 8 In another embodiment, based on the first coolant outlet temperature and the coolant target outlet temperature threshold, based on the rate of change of the charging current, the coolant flow rate and / or the coolant inlet temperature is controlled, and step S400 specifically includes:

[0147] Determine whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold, if so;

[0148] Then the vehicle exterior temperature control device 2 obtains the charging parameters of the battery pack from the charging device 3, and the charging parameters include the rate of change of the charging current;

[0149] Determine whether the charging current increases to the preset maximum current value and then begins to decrease within the fourth preset time period, and the absolute value of the charging current decrease rate is greater than or equal to the first preset current rate value. If so, increase the coolant flow rate, or reduce the coolant inlet temperature, or increase the coolant flow rate and reduce the coolant inlet temperature. It should be noted that during the charging process of the battery pack 1, the charging current increases to the preset maximum current value and then suddenly decreases significantly, which may be due to the excessive temperature of the battery pack 1. At this time, it is necessary to reduce the temperature of the battery pack 1 by increasing the coolant flow rate and / or reducing the coolant inlet temperature.

[0150] The embodiments of the present invention are shown in the attached Fig. 9 In other embodiments, based on the first coolant outlet temperature and the coolant target outlet temperature threshold, based on the rate of change of the charging power, the coolant flow rate and / or the coolant inlet temperature is controlled, and step S400 specifically includes:

[0151] Determine whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold, if so;

[0152] Then the vehicle exterior temperature control device 2 obtains the charging parameters of the battery pack from the charging device 3, and the charging parameters include the rate of change of the charging power;

[0153] Determine whether the charging power increases to the preset maximum power value and then starts to decrease within the fourth preset time period, and the absolute value of the charging power decrease rate is greater than or equal to the first preset power rate value. If so, increase the coolant flow rate, or reduce the coolant inlet temperature, or both the coolant flow rate and the coolant inlet temperature. It should be noted that during the charging process of the battery pack 1, the charging power increases to the preset maximum current value and then suddenly decreases significantly, which may be due to the excessive temperature of the battery pack 1. At this time, it is necessary to reduce the temperature of the battery pack 1 by increasing the coolant flow rate and / or reducing the coolant inlet temperature.

[0154] See attached Fig.10 In another embodiment, based on the first coolant outlet temperature and the coolant target outlet temperature threshold, based on the rate of change of the charging current, the coolant flow rate and / or the coolant inlet temperature is controlled, and step S400 specifically includes:

[0155] Determine whether the first coolant outlet temperature is less than the minimum coolant target outlet temperature threshold, if so;

[0156] Then the vehicle exterior temperature control device 2 obtains the charging parameters of the battery pack from the charging device 3, and the charging parameters include the rate of change of the charging current;

[0157] It is determined whether the charging current is greater than or equal to the first preset current value and continues for a fifth preset time before starting to decrease, and the absolute value of the charging current decrease rate is less than or equal to the second preset current rate value. If so, the coolant flow rate is reduced or the coolant input to the battery pack 1 is stopped. It should be noted that during the charging process of the battery pack 1, the charging current is greater than or equal to the first preset current value and continues for a long time, and then decreases smoothly. It can be seen that the battery pack 1 enters the buffer stage. At this time, the coolant flow rate can be reduced or the coolant input to the battery pack 1 can be stopped to reduce energy consumption.

[0158] See attached Fig.11 In other embodiments, based on the first coolant outlet temperature and the coolant target outlet temperature threshold, based on the rate of change of the charging power, the coolant flow rate and / or the coolant inlet temperature is controlled, and step S400 specifically includes:

[0159] Determine whether the first coolant outlet temperature is less than the minimum coolant target outlet temperature threshold, if so;

[0160] Then the vehicle exterior temperature control device 2 obtains the charging parameters of the battery pack from the charging device 3, and the charging parameters include the rate of change of the charging power;

[0161] It is determined whether the charging power is greater than or equal to the first preset power value and continues for a fifth preset time before starting to decrease, and the absolute value of the charging power decrease rate is less than or equal to the second preset power rate value. If so, the coolant flow rate is reduced or the coolant input to the battery pack 1 is stopped. It should be noted that during the charging process of the battery pack 1, the charging power is greater than or equal to the first preset power value and continues for a long time, and then decreases smoothly. It can be seen that the battery pack 1 enters the buffer stage. At this time, the coolant flow rate can be reduced or the coolant input to the battery pack 1 can be stopped to reduce energy consumption.

[0162] See attached Fig.12 A second aspect of an embodiment of the present invention provides a battery pack temperature control system for an electric vehicle, which is applied to the battery pack temperature control method for the electric vehicle, and the control system includes:

[0163] An acquisition unit 10 is used to acquire a first target inlet temperature, a first outlet temperature of the coolant, and a state of the battery pack from a charging device 3; wherein the state of the battery pack includes a charging state;

[0164] A judging unit 20, used to judge whether the battery pack 1 is in a charging state;

[0165] The control unit 30 is used to control the coolant inlet temperature entering the battery pack 1 to be a first target inlet temperature and the coolant flow rate to be a first preset flow rate when the battery pack 1 is in a charging state; and to control the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold.

[0166] The battery pack temperature control system of the electric vehicle provided by the embodiment of the present invention, on the one hand, the battery pack 1 will generate heat during the charging process, and the temperature of the battery pack 1 of the electric vehicle is controlled by using the external temperature control device 2, and the electric vehicle does not need to add an additional cooling system for the battery pack 1, thereby avoiding increasing the weight and cost of the electric vehicle and reducing the energy consumption of the electric vehicle during operation; on the other hand, based on the first outlet temperature of the coolant and the target outlet temperature threshold of the coolant, the coolant flow rate and / or the coolant inlet temperature are controlled, and during the charging process of the battery pack 1, the external temperature control device 2 does not interact with the battery pack 1 of the electric vehicle, and the temperature of the battery pack 1 of the electric vehicle is controlled, and there is no need to add software and hardware for the interaction between the electric vehicle and the battery pack 1, thereby improving the applicability and convenience of the external temperature control device 2 to the electric vehicle, and also saving costs.

[0167] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for controlling the temperature of a battery pack of an electric vehicle, characterized in that: The battery pack (1) is connected to an external temperature control device (2) and a charging device (3) respectively, and the temperature of the battery pack (1) is controlled by the external temperature control device (2); the temperature control method comprises the following steps: The vehicle exterior temperature control device (2) obtains the state of the battery pack from the charging device (3), wherein the state of the battery pack includes a charging state; The vehicle exterior temperature control device (2) determines whether the battery pack (1) is in the charging state, and if so, controls the inlet temperature of the coolant entering the battery pack (1) from the vehicle exterior temperature control device (2) to be a first target inlet temperature and the coolant flow rate to be a first preset flow rate; After the coolant is input into the battery pack (1) for a first preset time period, a first outlet temperature of the coolant is obtained; The coolant flow rate and / or the coolant inlet temperature are controlled based on the coolant first outlet temperature and the coolant target outlet temperature threshold.

2. The method for controlling the temperature of a battery pack of an electric vehicle according to claim 1, characterized in that: The step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold comprises: Determine whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold, and if so, increase the coolant flow rate and / or reduce the coolant inlet temperature; Determine whether the first coolant outlet temperature is less than a minimum coolant target outlet temperature threshold value; if so, reduce the coolant flow rate and / or increase the coolant inlet temperature.

3. The method for controlling the battery pack temperature of an electric vehicle according to claim 1, characterized in that: The step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold comprises: determining whether the coolant first outlet temperature falls within the coolant target outlet temperature threshold range, and if so, maintaining the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack (1).

4. The method for controlling the temperature of the battery pack of an electric vehicle according to claim 3, characterized in that: After the step of determining whether the first coolant outlet temperature falls within the coolant target outlet temperature threshold range, and if so, maintaining the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack (1), the control method further comprises: determining whether the difference between the maximum value of the coolant target outlet temperature threshold and the coolant first outlet temperature is greater than a preset difference; if so, maintaining the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack (1); otherwise, The vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack (1) from the charging device (3), the charging parameters including the rate of change of the charging current. If the rate of change of the charging current within a second preset time period is greater than zero, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging current within the second preset time period is not greater than zero, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack (1); or, the vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack from the charging device (3), the charging parameters including the rate of change of the charging power. If the rate of change of the charging power within the second preset time period is greater than zero, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging power within the second preset time period is not greater than zero, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack (1).

5. The method for controlling the temperature of a battery pack of an electric vehicle according to claim 1, characterized in that: The step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold further comprises: determining whether the first coolant outlet temperature falls within the coolant target outlet temperature threshold range; if so, determining whether the difference between the maximum value of the coolant target outlet temperature threshold and the first coolant outlet temperature is greater than a preset difference; if so, maintaining the first target inlet temperature and the first preset flow rate to control the temperature of the battery pack (1); otherwise, The vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack from the charging device (3), the charging parameters including the rate of change of the charging current. If the rate of change of the charging current within a second preset time period is greater than zero, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging current within the second preset time period is not greater than zero, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack (1); or, the vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack from the charging device (3), the charging parameters including the rate of change of the charging power. If the rate of change of the charging power within the second preset time period is greater than zero, the coolant flow rate is increased and / or the coolant inlet temperature is reduced. If the rate of change of the charging power within the second preset time period is not greater than zero, the first target inlet temperature and the first preset flow rate are maintained to control the temperature of the battery pack (1).

6. The method for controlling the battery pack temperature of an electric vehicle according to claim 2, characterized in that: The step of increasing the coolant flow rate and / or reducing the coolant inlet temperature comprises: Determine whether the first coolant outlet temperature is on an upward trend; if so, increase the coolant flow rate to obtain a first coolant flow rate, and / or reduce the coolant inlet temperature to obtain a first coolant inlet temperature; The first coolant flow rate satisfies the formula: in, Q 0 is the first preset flow rate of coolant per unit time; Q v1 is the first coolant flow rate per unit time; T N is the first outlet temperature of the coolant at the Nth moment; T N-1 is the first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k v1 is the first variation coefficient of coolant flow rate; ɑ 1 is a conversion factor greater than 0; And / or, the first coolant inlet temperature satisfies the following formula: in, T 0 is the first target inlet temperature; T 1 is the first coolant inlet temperature; T N For the N The first outlet temperature of the coolant at the moment; T N-1 is the first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k T1 is the first variation coefficient of the coolant inlet temperature; β 1 is a conversion factor greater than 0.

7. The method for controlling the battery pack temperature of an electric vehicle according to claim 2, characterized in that: The step of reducing the coolant flow rate and / or increasing the coolant inlet temperature comprises: Determine whether the first coolant outlet temperature is on a downward trend; if so, reduce the coolant flow rate to obtain a second coolant flow rate, and / or increase the coolant inlet temperature to obtain a second coolant inlet temperature; The second coolant flow rate satisfies the formula: in, Q 0 is the first preset flow rate of coolant per unit time; Q v2 is the second coolant flow rate; T N is the first outlet temperature of the coolant at the Nth moment; T N-1 is the first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k v2 is the second variation coefficient of coolant flow rate; ɑ 2 is a conversion factor greater than 0; And / or, the second coolant inlet temperature satisfies the following formula: in, T 0 is the first target inlet temperature; T 2 is the second coolant inlet temperature; T N is the first outlet temperature of the coolant at the Nth moment; T N-1 is the first outlet temperature of the coolant at the N-1th moment; Δt is the time difference between the Nth moment and the N-1th moment; k T is the change rate of the first outlet temperature of the coolant; k T2 is the second variation coefficient of coolant inlet temperature; β 2 is a conversion factor greater than 0.

8. The method for controlling the battery pack temperature of an electric vehicle according to any one of claims 1 to 7, characterized in that: The state of the battery pack also includes a state before charging; The control method further comprises: determining whether the battery pack (1) is in the pre-charging state, and if so, controlling the inlet temperature of the coolant entering the battery pack (1) from the vehicle exterior temperature control device (2) to be a first preset inlet temperature and the coolant flow rate to be a second preset flow rate; After the coolant is input into the battery pack (1) for a third preset time period, a third outlet temperature of the coolant is detected; Calculating an initial temperature of the battery pack based on the first preset inlet temperature and the third outlet temperature of the coolant; The first target inlet temperature and the first preset flow rate are determined based on an initial temperature of the battery pack.

9. The method for controlling the battery pack temperature of an electric vehicle according to claim 8, characterized in that: The step of determining the first target inlet temperature and the first preset flow rate based on the initial temperature of the battery pack includes: Obtaining a preset battery pack temperature threshold, wherein the battery pack temperature threshold includes at least one temperature interval, and each temperature interval is provided with a corresponding coolant inlet temperature and coolant flow rate; Determining the temperature interval in which the initial temperature of the battery pack is located; The coolant inlet temperature corresponding to the temperature range is determined to be the first target inlet temperature, and the coolant flow rate corresponding to the temperature range is determined to be the first preset flow rate.

10. The method for controlling the temperature of a battery pack of an electric vehicle according to claim 8, characterized in that: The initial temperature of the battery pack satisfies the formula: in, T B is the initial temperature of the battery pack; C is the volume heat capacity of the coolant; Q v is the coolant flow rate per unit time; h is the surface convection heat transfer coefficient; A The wall area that the coolant passes through when flowing through the internal flow channel of the battery pack per unit time; t The time it takes for the coolant to flow out of the internal flow channel of the battery pack; T in is a first preset inlet temperature; T out is the third outlet temperature of the coolant.

11. The method for controlling the battery pack temperature of an electric vehicle according to claim 1, characterized in that: The step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold comprises: Determining whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold, and if so, the vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack from the charging device (3), the charging parameters including the rate of change of the charging current; determining whether the charging current increases to a preset maximum current value and then begins to decrease within a fourth preset time period, and the absolute value of the charging current decrease rate is greater than or equal to a first preset current rate value, and if so, increasing the coolant flow rate and / or reducing the coolant inlet temperature; Or, determine whether the first coolant outlet temperature is greater than the maximum value of the coolant target outlet temperature threshold value. If so, the vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack from the charging device (3), and the charging parameters include the rate of change of the charging power; determine whether the charging power increases to a preset maximum power value within a fourth preset time period and then begins to decrease, and the absolute value of the charging power reduction rate is greater than or equal to the first preset power rate value. If so, increase the coolant flow rate and / or reduce the coolant inlet temperature.

12. The method for controlling the battery pack temperature of an electric vehicle according to claim 1, characterized in that: The step of controlling the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold comprises: Determining whether the first coolant outlet temperature is less than the minimum value of the coolant target outlet temperature threshold, and if so, the vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack from the charging device (3), the charging parameters including the rate of change of the charging current; determining whether the charging current is greater than or equal to a first preset current value and starts to decrease after continuing for a fifth preset time, and the absolute value of the charging current decrease rate is less than or equal to a second preset current rate value, and if so, reducing the coolant flow rate or stopping the coolant input into the battery pack (1); Or, determine whether the first outlet temperature of the coolant is less than the minimum value of the coolant target outlet temperature threshold value. If so, the vehicle exterior temperature control device (2) obtains the charging parameters of the battery pack from the charging device (3), and the charging parameters include the rate of change of the charging power; determine whether the charging power is greater than or equal to a first preset power value and starts to decrease after continuing for a fifth preset time, and the absolute value of the charging power reduction rate is less than or equal to a second preset power rate value. If so, reduce the coolant flow rate or stop the coolant input to the battery pack (1).

13. A battery pack temperature control system for an electric vehicle, characterized in that: The battery pack temperature control method for an electric vehicle according to any one of claims 1 to 12, wherein the control system comprises: An acquisition unit (10) is used to acquire the first target inlet temperature, the first outlet temperature of the coolant, and the state of the battery pack from the charging device (3); wherein the state of the battery pack includes a charging state; A judging unit (20) for judging whether the battery pack (1) is in the charging state; A control unit (30) is used to control the coolant inlet temperature entering the battery pack (1) to be a first target inlet temperature and the coolant flow rate to be a first preset flow rate when the battery pack (1) is in the charging state; and is used to control the coolant flow rate and / or the coolant inlet temperature based on the coolant first outlet temperature and the coolant target outlet temperature threshold.

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