Electric vehicle charging control method, storage medium and electric vehicle

Abstract

The invention provides an electric vehicle charging control method. According to the technical scheme, after charging is started, the temperature of the battery pack is collected according to a certain time interval, power is distributed according to the real-time temperature, and when the real-time temperature is larger than or smaller than a threshold value, a certain power is distributed from licensed power provided for the electric vehicle by a charging device to be used for a heat management system to refrigerate or heat the battery pack. According to the technical scheme, the method is simple in logic, convenient to use, efficient and energy-saving, reasonable and dynamic allocation of heating and cooling power and charging power is achieved for the output power of the charging device such as the charging pile, the remaining charging duration can be predicted according to the charging power, the charging energy efficiency is guaranteed, and therefore the charging process of the electric vehicle is safer, more efficient and more stable, and the charging efficiency is improved. And the method is more friendly to users. The technical scheme is generally suitable for direct current charging piles and alternating current charging piles of various current power gears.

Description

Technical Field

[0001] The present invention relates to the field of electric vehicles, and in particular to an electric vehicle charging control method, a storage medium and an electric vehicle. Background Art

[0002] Electric vehicles usually use multiple lithium-ion batteries connected in series and parallel to form a lithium-ion battery pack for power supply. Among them, the most commonly used lithium-ion batteries are lithium iron phosphate lithium-ion batteries and ternary lithium-ion batteries. When the energy of the lithium-ion battery pack is consumed, it needs to be recharged.

[0003] In order to ensure the high safety and long life of lithium-ion batteries and the normal performance, the lithium-ion battery pack needs to be kept in an appropriate temperature range during the charging process of electric vehicles, otherwise the battery pack needs to be heated or cooled. In the currently known technical solutions, when the temperature of the battery pack of an electric vehicle is too low or too high, the thermal management system of the electric vehicle itself is usually called to heat and cool the battery pack. However, how to reasonably and dynamically allocate the heating and cooling power and the charging power according to the output power of charging devices such as charging piles during the charging process, and ensure the safety, efficiency and stability of charging, is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present invention provides an electric vehicle charging control method with simple logic, easy use, high efficiency and energy saving, and provides corresponding storage media and electric vehicles, which are used to reasonably and dynamically adjust the heating and cooling power and the charging power according to the output power of charging devices such as charging piles, so as to make the charging process of the electric vehicle safer, more efficient and stable.

[0005] According to a first aspect of the present invention, a method for controlling charging of an electric vehicle is provided, wherein the electric vehicle charging process can call its own thermal management system to provide heating or cooling for the battery pack. The method is to collect the temperature T of the battery pack at a certain time interval Δt after starting charging. i , and perform the following power distribution control:

[0006] (1) If T II ≤T i ≤T III , then all the permitted power provided by the charging device to the electric vehicle is allocated to charging the battery pack;

[0007] (2) If T i >T III , then from the permitted power provided by the charging device to the electric vehicle, P r The power is used for the thermal management system to provide cooling for the battery pack, and the remaining power is allocated for charging the battery pack, where the cooling power P r for:

[0008] P r =min[(T i -T III ) / (T IV -T III ),1]*P rn (1)

[0009] (3) If Ti <T II , then from the permitted power provided by the charging device to the electric vehicle, P h The power is used for the thermal management system to heat the battery pack, and the remaining power is allocated for charging the battery pack, where the heating power P h for:

[0010] P h =min[(T II -T i ) / (T II -T I ),1]*P hn (2)

[0011] Above T I , T II , T III , T IV are the first temperature threshold, the second temperature threshold, the third temperature threshold, and the fourth temperature threshold of the battery pack, respectively, and T I <T II <T III <T IV ;P rn and P hn They are the maximum cooling power and maximum heating power of the thermal management system respectively; min means taking the smaller value in the brackets.

[0012] Optionally, in the above electric vehicle charging control method, the time interval Δt is between 1 second and 10 minutes.

[0013] Optionally, the above electric vehicle charging control method,

[0014] The first temperature threshold T I Between 0℃ and 15℃;

[0015] The second temperature threshold T II Between 15℃ and 25℃;

[0016] The third temperature threshold T III Between 35°C and 45°C;

[0017] The fourth temperature threshold T IV Between 45℃ and 55℃.

[0018] Optionally, the above-mentioned electric vehicle charging control method further includes predicting the remaining time t required for full charging in real time according to the following steps during the charging process:

[0019] Step S1: Obtain the total power E of the battery pack t and the current electrical energy E i ;

[0020] Step S2: Obtain the battery pack charging power at the current moment and at m moments before the current moment, and record them as P i-0 , P i-1 , P i-2 ,…,P i-j ,…,P i-m , where j is an integer between 0 and m;

[0021] Step S3: Calculate the weighted average charging power P of the battery pack e :

[0022]

[0023] Where f i-0 , f i-1 , f i-2 , …, f i-j , …, f i-m are weighting coefficients between 0 and 1;

[0024] Step S4, calculate the remaining time t required for full charging:

[0025] t=(E t -E i ) / P e (4)

[0026] E above t and E i They are the total power of the battery pack when it is fully charged and the power it has at the current moment, i.e. the current power.

[0027] Optionally, in the above electric vehicle charging control method, the series of weighting coefficients f in step S3 are i-0 , f i-1 , f i-2 , …, f i-j , …, f i-m , if the value of j is smaller, the corresponding weighted coefficient value is larger.

[0028] Optionally, the above electric vehicle charging control method further includes calculating the energy efficiency index EFF in real time during the charging process. i , if the current energy efficiency index EFF i Less than the energy efficiency index threshold EFF c, the electric vehicle is forced to stop supplying power t r Restart charging after a certain period of time;

[0029] Energy efficiency index EFF at the current moment i It is the ratio of the arithmetic mean of the charging power of each battery pack at the current moment and the q moments before the current moment to the arithmetic mean of the power of each thermal management system at the above q+1 moments, where the power of the thermal management system at each moment includes its heating power and cooling power.

[0030] Optionally, in the above electric vehicle charging control method, the energy efficiency index threshold EFF c Between 0.1 and 10.

[0031] Optionally, in the above-mentioned electric vehicle charging control method, if the power calculated at a certain moment to be allocated to the thermal management system for heating or cooling is greater than the permitted power provided by the charging device to the electric vehicle, the entire permitted power is used for the thermal management system.

[0032] According to a second aspect of the present invention, there is provided a computer-readable storage medium storing a plurality of control instructions, wherein the control instructions are suitable for loading by a processor to execute any one of the above-mentioned electric vehicle charging control methods.

[0033] According to a third aspect of the present invention, there is provided an electric vehicle, which is equipped with the computer-readable storage medium. Further, the electric vehicle applies any of the above-mentioned electric vehicle charging control methods.

[0034] The beneficial effects of the technical solution of the present invention are introduced below in combination with the principle thereof.

[0035] First, in the technical solution of the present invention, the allocation between charging power and cooling and heating power is dynamically adjusted according to the temperature of the battery pack during charging. The technical solution sets four temperature thresholds, among which: the first temperature threshold T I Represents the lower limit warning value of charging temperature, the second temperature threshold T II Represents the lower limit of the most suitable charging temperature, the third temperature threshold T III Represents the upper limit of the most suitable charging temperature, the fourth temperature threshold T IV Represents the upper limit warning value of charging temperature. After starting charging, collect the temperature T of the battery pack at a certain time interval Δt i , and perform the following power distribution control:

[0036] (1) If T II ≤T i ≤T III , then the current battery pack temperature T iIn the most suitable charging temperature range, all the permitted power provided by the charging device to the electric vehicle is allocated to charging the battery pack;

[0037] (2) If T i >T III , it means that the current battery pack temperature is too high and cooling is required. The cooling power P r for:

[0038] P r =min[(T i -T III ) / (T IV -T III ),1]*P rn (1)

[0039] That is, if the current battery pack temperature T i Deviation from the third temperature threshold T III The more, the greater the allocated cooling power; if the current battery pack temperature T i ≥ the fourth temperature threshold T IV , then the allocated cooling power is equal to its maximum value P rn .

[0040] (3) If T i <T II , it means that the current battery pack temperature is too low and heating needs to be started, where the heating power P h for:

[0041] P h =min[(T II -T i ) / (T II -T I ),1]*P hn (2)

[0042] That is, if the current battery pack temperature T i Deviation from the second temperature threshold T II The more, the greater the allocated heating power; if the current battery pack temperature T i ≤ the second temperature threshold T II , then the allocated heating power is equal to its maximum value P hn .

[0043] Secondly, the technical solution of the present invention provides a function for predicting the remaining charging time. If part of the permitted power provided by the charging device to the electric vehicle is provided to the thermal management system for heating or cooling the battery pack, the power available for charging will be reduced, which will extend the charging time. Considering that the permitted power provided by the charging device to the electric vehicle may change in practice, and the power used by the thermal management system for heating or cooling the battery pack also changes dynamically, the weighted average method is used to predict the weighted average charging power P of the battery pack. e , which is calculated by weighted average statistics of charging power at each historical moment, and the charging power value closer to the current moment has a greater weight.

[0044] Finally, the technical solution of the present invention takes into account the charging energy efficiency problem, and continuously calculates the energy efficiency index EFF in real time during the charging process. i , if the current energy efficiency index EFF i Less than the energy efficiency index threshold EFF c , it means that due to the low or high ambient temperature in the current period, a considerable amount of electric energy is used for heating or cooling the battery pack, while the electric energy used for actual charging is relatively small, which is in a very inefficient charging state. r Restart charging after waiting for a certain period of time. r After a certain period of time, the ambient temperature becomes suitable and higher charging efficiency can be achieved after restarting charging. This approach is conducive to ensuring higher charging efficiency and avoiding a large amount of energy being wasted due to inefficient heating or cooling.

[0045] Therefore, the technical solution of the present invention is simple in logic, easy to use, and energy-efficient. It realizes reasonable dynamic allocation of heating and cooling power and charging power according to the output power of charging devices such as charging piles, and can predict the remaining charging time according to the charging power, and ensure the charging energy efficiency, so that the charging process of electric vehicles is safer, more efficient, more stable, and more user-friendly. This technical solution is generally applicable to DC charging piles and AC charging piles of various power levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a control flow chart of the electric vehicle charging control method in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0048] like Figure 1 As shown, a method for controlling charging of an electric vehicle is provided. During the charging process of the electric vehicle, the electric vehicle can call its own thermal management system to provide heating or cooling for the battery pack. The method is to collect the temperature T of the battery pack at a certain time interval Δt after starting charging. i, and perform the following power distribution control:

[0049] (1) If T II ≤T i ≤T III , then all the permitted power provided by the charging device to the electric vehicle is allocated to charging the battery pack;

[0050] (2) If T i >T III , then from the permitted power provided by the charging device to the electric vehicle, P r The power is used for the thermal management system to provide cooling for the battery pack, and the remaining power is allocated for charging the battery pack, where the cooling power P r for:

[0051] P r =min[(T i -T III ) / (T IV -T III ),1]*P rn (1)

[0052] (3) If T i <T II , then from the permitted power provided by the charging device to the electric vehicle, P h The power is used for the thermal management system to heat the battery pack, and the remaining power is allocated for charging the battery pack, where the heating power P h for:

[0053] P h =min[(T II -T i ) / (T II -T I ),1]*P hn (2)

[0054] Above T I , T II , T III , T IV are the first temperature threshold, the second temperature threshold, the third temperature threshold, and the fourth temperature threshold of the battery pack, respectively, and T I <T II <T III <T IV ;P rn and P hn They are the maximum cooling power and maximum heating power of the thermal management system respectively; min means taking the smaller value in the brackets.

[0055] All or part of the power allowed by the charging device for the electric vehicle is allocated for charging the battery pack, but whether the battery pack actually charges all of this power is still controlled by the electric vehicle's own battery management system BMS. The BMS determines how much of the allocated charging power is used for actual charging based on parameters such as the battery pack's temperature, state of charge, and health.

[0056] For example, in one embodiment, at a certain moment, the permitted power provided by the charging device to the electric vehicle is 100 kW, of which 10 kW is allocated for battery pack heating and the remaining 90 kW is allocated for battery pack charging, but the battery pack actually only uses 70 kW for charging.

[0057] Specifically, one or more temperature sensors are provided in the battery pack to collect the temperature of the battery pack. If there are multiple temperature sensors, the arithmetic average of their measured values ​​is used as the battery pack temperature value.

[0058] Specifically, the entire electric vehicle charging control is judged and decided in real time by the vehicle controller. The vehicle controller communicates with the charging device to obtain the permitted power provided by the charging device to the electric vehicle in real time. The electric vehicle obtains the power provided by the charging device through the on-board charger (OBC), and the power distribution unit (PDU) performs the distribution between charging power and cooling and heating power under the regulation of the vehicle controller.

[0059] Taking into account the power supply scheduling of the power grid and the working status of the charging device itself, in many cases the permitted power provided by the charging device to the electric vehicle changes in real time.

[0060] Preferably, in the above electric vehicle charging control method, the time interval Δt is between 1 second and 10 minutes.

[0061] Preferably, the above-mentioned electric vehicle charging control method,

[0062] The first temperature threshold T I Between 0℃ and 15℃;

[0063] The second temperature threshold T II Between 15℃ and 25℃;

[0064] The third temperature threshold T III Between 35°C and 45°C;

[0065] The fourth temperature threshold T IV Between 45℃ and 55℃.

[0066] Preferably, the above-mentioned electric vehicle charging control method further comprises predicting the remaining time t required for full charging in real time according to the following steps during the charging process:

[0067] Step S1: Obtain the total power E of the battery pack t and the current electrical energy E i ;

[0068] Step S2: Obtain the battery pack charging power at the current moment and at m moments before the current moment, and record them as P i-0 , P i-1 , P i-2 ,…,P i-j ,…,P i-m , where j is an integer between 0 and m;

[0069] Step S3: Calculate the weighted average charging power P of the battery pack e :

[0070]

[0071] Where f i-0 , f i-1 , f i-2 , …, f i-j , …, f i-m are weighting coefficients between 0 and 1;

[0072] Step S4, calculate the remaining time t required for full charging:

[0073] t=(E t -E i ) / P e (4)

[0074] E above t and E i They are the total power of the battery pack when it is fully charged and the power it has at the current moment, i.e. the current power.

[0075] Specifically, the total electric energy E of the battery pack when it is fully charged t and the electrical energy E currently available i Obtained by querying the battery management system BMS.

[0076] Preferably, in the above electric vehicle charging control method, the series of weighting coefficients f in step S3 are i-0 , f i-1 , f i-2 , …, f i-j , …, f i-m , if the value of j is smaller, the corresponding weighted coefficient value is larger.

[0077] Preferably, the above-mentioned electric vehicle charging control method further comprises calculating the energy efficiency index EFF in real time during the charging process. i , if the current energy efficiency index EFF i Less than the energy efficiency index threshold EFF c , the electric vehicle is forced to stop supplying power t r Restart charging after a certain period of time;

[0078] Energy efficiency index EFF at the current moment i It is the ratio of the arithmetic mean of the charging power of each battery pack at the current moment and the q moments before the current moment to the arithmetic mean of the power of each thermal management system at the above q+1 moments, where the power of the thermal management system at each moment includes its heating power and cooling power.

[0079] Preferably, q is between 5 and 100.

[0080] Preferably, the duration of the above power supply suspension is r Between 0.5 hours and 5 hours.

[0081] Preferably, in the above-mentioned electric vehicle charging control method, the energy efficiency index threshold EFF c Between 0.1 and 10.

[0082] Preferably, in the above-mentioned electric vehicle charging control method, if the power calculated at a certain moment to be allocated to the thermal management system for heating or cooling is greater than the permitted power provided by the charging device to the electric vehicle, the entire permitted power is used for the thermal management system.

[0083] The present invention also provides a computer-readable storage medium storing a plurality of control instructions, wherein the control instructions are suitable for being loaded by a processor to execute the above-mentioned electric vehicle charging control method.

[0084] The present invention also provides an electric vehicle, which is equipped with the computer-readable storage medium. Furthermore, the electric vehicle applies the electric vehicle charging control method.

[0085] Example

[0086] Please refer to Figure 1 A more specific embodiment is understood.

[0087] For an electric vehicle using a lithium iron phosphate battery pack, the first temperature threshold T I =5°C, the second temperature threshold T II =20°C, the third temperature threshold T III =40°C, the fourth temperature threshold T IV =50℃, the maximum cooling power of the thermal management system P rn =6kW, maximum heating power Phn =9kW. Heating relies on the PTC heater, which is a PTC wire mesh wrapped on the battery shell, which is directly used to heat the battery; cooling relies on the vehicle air conditioner, which exchanges heat with the coolant in the liquid cooling plate at the bottom of the battery pack through the heat exchanger, thereby indirectly cooling the battery pack. In this embodiment, the time interval Δt = 1min, the energy efficiency index threshold EFF c =2.

[0088] One day, the electric car started charging in a cold environment.

[0089] When charging is started, the charging device provides the electric vehicle with a permissible power of 50 kW and the battery pack temperature T i =2℃ <T II , then min[(T II -T i ) / (T II -T I ),1]=min[(20-2) / (20-5),1]=1, so P is allocated from the permitted power provided by the charging device to the electric vehicle. h =1*P hn =9kW of power is used for the thermal management system to provide heating for the battery pack, and the remaining power of 41kW is allocated for charging the battery pack.

[0090] After a period of time, the charging device provides the electric vehicle with a permitted power of 46 kW, and the battery pack temperature T i =10℃ <T II , then min[(T II -T i ) / (T II -T I ),1]=min[(20-10) / (20-5),1]=2 / 3, so P is allocated from the permitted power provided by the charging device to the electric vehicle. h =(2 / 3)*P hn =6kW of power is used for the thermal management system to provide heating for the battery pack, and the remaining power of 40kW is allocated for charging the battery pack.

[0091] After a period of time, the battery pack charging power at the current time and the five times before the current time is obtained, which are P i-0 =32kW, P i-1 =35kW, P i-2 =38kW, P i-3 =36kW, P i-4 =42kW, P i-5 =45kW; the weighting coefficients corresponding to these 6 powers are f i-0 =0.5, f i-1 =0.6, fi-2 =0.7, f i-3 =0.8, f i-4 =0.9, f i-5 =1.

[0092] Calculate the weighted average charging power P of the battery pack e for:

[0093] P e =(32*0.5+35*0.6+38*0.7+36*0.8+42*0.9+45*1) / (0.5+0.6+0.7+0.8+0.9+1)=38.9kW.

[0094] The total energy E of the fully charged battery pack is obtained through the battery management system BMS. t = 100kWh, the current electrical energy E i =40kWh, so the remaining time required to fully charge is t = (E t -E i ) / P e =(100-40) / 38.9=1.54h.

[0095] In this embodiment, the energy efficiency index EFF at the current moment i It is the ratio of the arithmetic mean of the charging power of each battery pack at the current moment and the 10 moments before the current moment to the arithmetic mean of the power of each thermal management system at the above 10 moments, where the power of the thermal management system at each moment includes its heating power and cooling power. i Both are greater than 2, so the charging pause operation is not performed throughout the process.

[0096] The technical solution in this embodiment is simple in logic, easy to use, and energy-efficient. It can realize reasonable dynamic allocation of heating and cooling power and charging power according to the output power of charging devices such as charging piles, and can predict the remaining charging time according to the charging power and ensure the charging energy efficiency, so that the charging process of electric vehicles is safer, more efficient, more stable, and more user-friendly. Its technical solution is generally applicable to DC charging piles and AC charging piles of various power levels.

Claims

1. A method for controlling charging of an electric vehicle, wherein the electric vehicle charging process can call its own thermal management system to provide heating or cooling for the battery pack, characterized in that: After starting charging, collect the temperature T of the battery pack at a certain time interval Δt i , and perform the following power distribution control: (1) If T II ≤T i ≤T III , then all the permitted power provided by the charging device to the electric vehicle is allocated to charging the battery pack; (2) If T i >T III , then from the permitted power provided by the charging device to the electric vehicle, P r The power is used for the thermal management system to provide cooling for the battery pack, and the remaining power is allocated for charging the battery pack, where the cooling power P r for: P r =min[(T i -T III ) / (T IV -T III ),1]*P rn (1) (3) If T i <T II , then from the permitted power provided by the charging device to the electric vehicle, P h The power is used for the thermal management system to heat the battery pack, and the remaining power is allocated for charging the battery pack, where the heating power P h for: P h =min[(T II -T i ) / (T II -T I ),1]*P hn (2) Above T I 、T II 、T III 、T IV are the first temperature threshold, the second temperature threshold, the third temperature threshold, and the fourth temperature threshold of the battery pack, respectively, and T I <T II <T III <T IV ;P rn and P hn They are the maximum cooling power and maximum heating power of the thermal management system respectively; min means taking the smaller value in the brackets.

2. The electric vehicle charging control method according to claim 1, characterized in that: The time interval Δt is between 1 second and 10 minutes.

3. The electric vehicle charging control method according to claim 1, characterized in that: The first temperature threshold T I Between 0℃ and 15℃; The second temperature threshold T II Between 15℃ and 25℃; The third temperature threshold T III Between 35°C and 45°C; The fourth temperature threshold T IV Between 45℃ and 55℃.

4. The electric vehicle charging control method according to claim 1, characterized in that: The charging process also includes real-time prediction of the remaining time t required for full charging according to the following steps: Step S1: Obtain the total power E of the battery pack t and the current electrical energy E i ; Step S2: Obtain the battery pack charging power at the current moment and at m moments before the current moment, and record them as P i-0 , P i-1 , P i-2 ,…,P i-j ,…,P i-m , where j is an integer between 0 and m; Step S3: Calculate the weighted average charging power P of the battery pack e : Where f i-0 , f i-1 , f i-2 , …, f i-j , …, f i-m are weighting coefficients between 0 and 1; Step S4, calculate the remaining time t required for full charging: t=(E t -E i ) / P e (4) E above t and E i They are the total power of the battery pack when it is fully charged and the power it has at the current moment, i.e. the current power.

5. The electric vehicle charging control method according to claim 4, characterized in that: The series of weighting coefficients f described in step S3 i-0 , f i-1 , f i-2 , …, f i-j , …, f i-m , if the value of j is smaller, the corresponding weighted coefficient value is larger.

6. The electric vehicle charging control method according to claim 1, characterized in that: It also includes real-time calculation of the energy efficiency index EFF during the charging process i , if the current energy efficiency index EFF i Less than the energy efficiency index threshold EFF c , the electric vehicle is forced to stop supplying power t r Restart charging after a certain period of time; Energy efficiency index EFF at the current moment i It is the ratio of the arithmetic mean of the charging power of each battery pack at the current moment and the q moments before the current moment to the arithmetic mean of the power of each thermal management system at the above q+1 moments, where the power of the thermal management system at each moment includes its heating power and cooling power.

7. The electric vehicle charging control method according to claim 6, characterized in that: The energy efficiency index threshold EFF c Between 0.1 and 10.

8. The electric vehicle charging control method according to claim 1, characterized in that: If the power calculated at a certain moment to be allocated to the thermal management system for heating or cooling is greater than the permitted power provided by the charging device to the electric vehicle, the entire permitted power is used for the thermal management system.

9. A computer-readable storage medium storing a plurality of control instructions, characterized in that: The control instruction is suitable for loading into a processor to execute the electric vehicle charging control method according to any one of claims 1 to 8.

10. An electric vehicle, characterized in that: The computer-readable storage medium according to claim 9 is mounted.

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