Heating method and heating system of battery and electric automobile comprising heating systemTechnical Field
The invention relates to a heating method and a heating system of a battery and an electric automobile comprising the heating system, and belongs to the field of electric automobiles.
Background
The battery, especially the lithium ion battery, has greatly reduced electrical performance in low temperature environment due to its own characteristics, and cannot meet the normal use requirements. Especially, under low temperature environment, lithium ion battery's charge time is long, can reduce customer's experience and install lithium ion battery's whole car availability factor of electric automobile additional, consequently, need heat the battery in order to promote the battery performance under the low temperature environment.
At present, the heating of the battery in the industry can be generally divided into external heating and internal heating (self-heating), the external heating is to heat the battery cell by using an external heat source, for example: high temperature liquid, PTC (positive temperature coefficient) heater or resistance wire heating sheet (membrane), etc., but the external heating mode has the disadvantages of slow heating speed, low efficiency and large temperature difference in the heating process (temperature difference between cells in each area and temperature difference between the surface of the cell and the inside of the cell), which will cause adverse effect on the consistency and service life of the system and even cause safety accidents due to thermal runaway. Internal heating (self-heating) is generally a method of performing cyclic charge and discharge between a target battery system and a capacitor or a second battery system (i.e., another battery system), and the target battery system itself generates heat to increase the temperature during the cyclic charge and discharge. However, this approach requires additional electronics, such as: a capacitor, an inductor, DCDC (a device for converting a dc power supply of a certain voltage level into a dc power supply of another voltage level), and even a second battery system, increase costs and occupy a large space, and thus, there are not many cases where they are actually used for actual products.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a method and a system for heating a battery, and an electric vehicle including the heating system, which can solve the technical problems of low heating efficiency, large system temperature difference, high cost and large occupied space.
In order to achieve the purpose, the invention adopts the following technical scheme: a method of heating a battery, comprising:
1) when the battery system is charged, the temperature of each part of a battery pack module of the battery system is collected;
2) and according to the acquired temperature and the preset conditions, carrying out external heating, cyclic pulse charging or conventional charging on a battery pack module of the battery system.
Further, the specific process of step 2) is as follows:
2.1) judging whether the minimum value of the collected temperatures of all parts meets the preset cyclic pulse charging condition by the BMS, and if so, entering the step 2.2); if not, performing external heating on a battery pack module of the battery system by using an external heating device, and then entering the step 1);
2.2) a charger is adopted to carry out cyclic pulse charging on a battery pack module of the battery system, and in the pulse charging process, the BMS judges whether the minimum value of the collected temperature of each part meets the preset conventional charging condition or not, if so, the step 2.3 is carried out; if not, continuing to carry out cyclic pulse charging;
and 2.3) the BMS sends a conventional charging request to a charger, and the charger performs conventional charging on the battery pack module of the battery system to finish charging of the battery system.
Further, the specific process of cyclic pulse charging in step 2.2) is as follows:
the BMS closes a relay of a battery system and sends a pulse charging request to a charger;
the charger carries out cyclic pulse charging on the battery pack module of the battery system according to the charging current of the pulse charging request;
and thirdly, repeating the step II until the temperature of the battery pack module is greater than or equal to a preset second temperature threshold value.
Furthermore, in the step two, one cycle of cyclic pulse charging sequentially charges the first current for a plurality of seconds, takes a rest for a plurality of seconds and charges the second current for a plurality of seconds.
Further, the cyclic pulse charging condition is whether the cyclic pulse charging condition is greater than or equal to a preset first temperature threshold and smaller than a preset second temperature threshold;
the normal charging condition is whether the normal charging condition is greater than or equal to a preset second temperature threshold value.
Further, the temperature of each part of the battery pack module of the battery system is collected by the BMS in the step 1).
Further, the external heating device in the step 2.1) adopts a liquid thermal system, a PTC or a resistance wire heater.
A heating system for a battery, comprising:
the parameter setting module is used for presetting conditions;
the external heating device is used for externally heating the battery pack module of the battery system according to the temperature of each part of the battery pack module of the battery system and preset conditions;
and the charging module is used for carrying out cyclic pulse charging or conventional charging on the battery pack module of the battery system through the charger according to the temperature of each part of the battery pack module of the battery system and preset conditions.
Further, the charging module includes:
the circulating pulse charging unit is used for carrying out circulating pulse charging on the battery pack module of the battery system through the charger according to the acquired temperature, the preset circulating pulse charging condition and the pulse charging request;
and the conventional charging unit is used for conventionally charging the battery pack module of the battery system through the charger according to the acquired temperature, the preset conventional charging condition and the conventional charging request.
An electric vehicle, characterized by a heating system comprising a battery.
Due to the adoption of the technical scheme, the invention has the following advantages:
1. the battery heating method provided by the invention is divided into three stages, and the battery pack module of the battery system is subjected to external heating, pulse charging or conventional charging, so that the battery heating method has the advantages of high heating speed, high efficiency and good temperature consistency, and can avoid the risk of lithium precipitation possibly caused by overlarge temperature difference between the inside and the outside of the battery core due to conventional external heating.
2. Compared with the traditional self-heating mode, the invention does not need to add additional energy storage devices such as batteries or capacitance and inductance, has simple structure and small occupied space, and can be widely applied to the field of electric automobiles.
Drawings
FIG. 1 is a flow chart of a method provided by an embodiment of the present invention;
fig. 2 is a schematic diagram of three-stage external heating or charging provided by an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The invention utilizes the characteristic that the heat generation power of the battery during charging under low temperature and low SOC (state of charge), and according to the temperature of each part of the battery pack module of the acquired battery system, the external heating or charging of the battery pack module is carried out in three stages, including a first stage (external heating), a second stage (cyclic pulse charging) and a third stage (conventional charging), wherein the first stage (if existing) is only subjected to external heating and is not charged, the second stage comprises a plurality of continuous pulse charging cycles, and the third stage stops pulse charging and carries out conventional charging. According to the invention, additional energy storage devices such as batteries or capacitance and inductance are not required to be added, and the temperature rise rate of the battery core can reach 1-1.5 ℃/min, which is far greater than that of a conventional heating system by 0.3-0.6 ℃/min. In addition, the three stages of the present invention are not limited to this embodiment, and a suitable charging process may be formulated based on a specific electrical core characteristic, including a charging temperature, a pulse, a magnitude of a continuous charging current, and the like.
Example 1
As shown in fig. 1 and fig. 2, the present embodiment provides a method for heating a battery, including the following steps:
1) when the battery system is charged, the temperature of each part of the battery pack module of the battery system is collected, for example: collected by BMS (battery management system).
2) According to the minimum value Tmin of the temperatures of all the collected parts and a preset temperature threshold value, an external heating device or a charger is adopted to externally heat, circularly and pulse charge or conventionally charge a battery pack module of the battery system, wherein the temperature threshold value comprises a first temperature threshold value (for example-20 ℃) and a second temperature threshold value (for example 10 ℃), and the temperature threshold value can be set according to specific conditions, specifically:
2.1) first stage: the BMS judges whether the minimum value Tmin of the temperatures of all the parts is greater than or equal to a preset first temperature threshold value and smaller than a preset second temperature threshold value, and if so, for example, when the temperature Tmin is greater than or equal to minus 20 ℃ and less than 10 ℃, the step 2.2) is carried out; if not, the external heating device is adopted to externally heat the battery pack module of the battery system, and then the step 1) is carried out to acquire the temperature of each part of the battery pack module of the battery system again, wherein the external heating device can adopt a liquid thermal system, a PTC or a resistance wire heater.
2.2) second stage: a charger is adopted to carry out cyclic pulse charging on a battery pack module of the battery system, and in the pulse charging process, the BMS judges whether the minimum Tmin of the collected temperatures of all parts is greater than or equal to a preset second temperature threshold value or not, and if yes, for example, when the Tmin is greater than or equal to 10 ℃, the step 2.3 is carried out); if not, the cyclic pulse charging is continued, and the specific process of the cyclic pulse charging is as follows:
BMS closes the relay of the battery system and sends a pulse charging request to the charger.
Secondly, the charger performs cyclic pulse charging on the battery pack module of the battery system according to the charging current of the pulse charging request, wherein one cyclic pulse charging cycle sequentially comprises a first current (such as large current)charging 10s, a rest charging 10s and a second current (such as small current) charging, namelyconventional charging 10s, and the charging current, the large current and the small current can be calibrated according to the system of the battery system, the specification of the battery pulse current and the like, and the specific process is not repeated herein.
And thirdly, repeating the step II until the temperature of the battery pack module is greater than or equal to a preset second temperature threshold value.
2.3) third stage: the BMS sends a regular charging request to the charger, and the charger carries out regular charging, namely regular sectional charging (stepcharge), on the battery pack module of the battery system according to the regular charging request sent by the BMS until a preset charging cut-off condition is triggered (for example, a lithium iron phosphate battery stops charging when the maximum voltage of a single battery is 3.65V; and a ternary battery stops charging when the maximum voltage of the single battery is 4.25V), so that the charging of the battery system is completed.
Example 2
The embodiment provides a heating system of a battery, which comprises a parameter setting module, an external heating device and a charging module.
The parameter setting module is used for presetting conditions including a cyclic pulse charging condition and a conventional charging condition, wherein the cyclic pulse charging condition is whether the cyclic pulse charging condition is larger than or equal to a preset first temperature threshold and smaller than a preset second temperature threshold, and the conventional charging condition is whether the conventional charging condition is larger than or equal to a preset second temperature threshold.
The external heating device is used for externally heating the battery pack module of the battery system according to the minimum value of the temperature of each part of the battery pack module of the battery system and preset conditions.
The charging module is used for carrying out cyclic pulse charging or conventional charging on the battery pack module of the battery system through the charger according to the minimum value of the temperature of each part of the battery pack module of the battery system and preset conditions.
In a preferred embodiment, the charging module comprises a cyclic pulse charging unit and a conventional charging unit.
And the cyclic pulse charging unit is used for carrying out cyclic pulse charging on the battery pack module of the battery system through the charger according to the minimum value of the collected temperatures of all parts, a preset temperature threshold value and a pulse charging request.
And the conventional charging unit is used for conventionally charging the battery pack module of the battery system through the charger according to the acquired minimum value of the temperature of each part, the preset conventional charging condition and the conventional charging request.
In a preferred embodiment, the external heating device may employ a hydro-thermal system, a PTC or a resistance wire heater.
In a preferred embodiment, the temperatures of the respective portions of the battery pack module of the battery system may be collected using a BMS.
The above embodiments are only used for illustrating the present invention, and the structure, connection mode, manufacturing process, etc. of the components may be changed, and all equivalent changes and modifications performed on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.