阅读说明：本技术 一种电动汽车及其电池自唤醒加热方法 (Electric automobile and battery self-awakening heating method thereof ) 是由 王勇士 赵宇斌 石赵伟 于 2020-06-12 设计创作，主要内容包括：本发明提供一种电动汽车及其电池自唤醒加热方法,属于新能源电动汽车领域。该方法包括：车辆处于停车状态时,按照设定的自唤醒频率定期检测电池温度；判断检测到的电池温度是否低于电池停车加热开启阈值,若低于,则对电池进行加热,在加热过程中判断电池的温度是否达到电池停车加热关闭阈值,若达到,则停止对电池加热；根据车辆停车前的电池行车加热开启温度确定所述电池停车加热开启阈值,进而确定所述电池停车加热关闭阈值,所述电池行车加热开启温度是用来在车辆处于行车状态时判断是否对电池进行加热的温度。将电池停车加热开启阈值与车辆停车前的电池行车加热开启温度相关联,保证了加热后的电池温度能满足驾驶人员对车辆性能的需求。(The invention provides an electric automobile and a battery self-awakening heating method thereof, and belongs to the field of new energy electric automobiles. The method comprises the following steps: when the vehicle is in a parking state, periodically detecting the temperature of the battery according to a set self-awakening frequency; judging whether the detected battery temperature is lower than a battery shutdown heating starting threshold or not, if so, heating the battery, judging whether the temperature of the battery reaches the battery shutdown heating closing threshold or not in the heating process, and if so, stopping heating the battery; and determining the battery parking heating starting threshold according to the battery driving heating starting temperature before the vehicle stops, and further determining the battery parking heating closing threshold, wherein the battery driving heating starting temperature is used for judging whether to heat the battery when the vehicle is in a driving state. The battery parking heating starting threshold value is related to the battery driving heating starting temperature before the vehicle is parked, so that the heated battery temperature can meet the requirement of a driver on the vehicle performance.)

1. A method of self-waking up a battery for heating, the method comprising the steps of:

(1) when the vehicle is in a parking state, periodically detecting the temperature of the battery according to a set self-awakening frequency;

(2) judging whether the detected battery temperature is lower than a battery shutdown heating starting threshold or not, if so, heating the battery, judging whether the temperature of the battery reaches the battery shutdown heating closing threshold or not in the heating process, and if so, stopping heating the battery;

the method comprises the steps of determining a battery parking heating starting threshold according to a battery driving heating starting temperature before a vehicle stops, and further determining a battery parking heating stopping threshold, wherein the battery driving heating starting temperature is used for judging whether to heat a battery when the vehicle is in a driving state.

2. The battery self-awakening heating method according to claim 1, wherein the calculation process of the battery driving heating starting temperature before the vehicle stops comprises the following steps:

obtaining expected maximum discharge current according to the maximum discharge current and the power performance coefficient output by the battery in a control period before the vehicle stops;

obtaining the temperature corresponding to the expected maximum discharge current as a first expected temperature according to the corresponding relation between the predetermined battery charge-discharge current and the temperature and the expected maximum discharge current;

and obtaining the heating starting temperature of the battery running vehicle before the vehicle stops according to the first expected temperature.

3. The battery self-awakening heating method according to claim 2, wherein the first expected temperature is adjusted, and the adjusted first expected temperature is used as a battery driving heating starting temperature before the vehicle stops; wherein the following steps are iteratively performed to adjust the first desired temperature: on the basis of the first expected temperature, when the energy of the battery, which can be converted into the vehicle power, is more than zero after the first set degree is increased, the first expected temperature is added with the first set degree until the energy of the battery, which can be converted into the vehicle power, is less than or equal to zero after the first set degree is increased, and the adjusted first expected temperature is obtained.

4. The battery self-awakening heating method according to claim 2, wherein the calculation process of the battery driving heating starting temperature before the vehicle stops further comprises the following steps:

obtaining expected maximum charging current according to the maximum charging current output by the battery in a control period before the vehicle stops and the electric braking performance coefficient;

obtaining the temperature corresponding to the expected maximum charging current as a second expected temperature according to the corresponding relation between the predetermined battery charging and discharging current and the temperature and the expected maximum charging current;

comparing the first expected temperature with the second expected temperature, and taking the maximum value as the final expected temperature;

and obtaining the heating starting temperature of the battery running vehicle before the vehicle stops according to the final expected temperature.

5. The battery self-awakening heating method according to claim 4, wherein the final desired temperature is adjusted, and the adjusted final desired temperature is used as a battery driving heating start temperature before the vehicle stops; wherein the following steps are iteratively performed to adjust the final desired temperature: on the basis of the final expected temperature, when the energy which can be converted into the vehicle power by the battery is more than zero after the second set degree is increased, the final expected temperature is added with the second set degree until the energy which can be converted into the vehicle power by the battery is less than or equal to zero after the second set degree is increased, and the adjusted final expected temperature is obtained.

6. The battery self-wake-up heating method according to any one of claims 1 to 5, characterized in that the battery state of charge is also detected periodically according to a set self-wake-up frequency, and the battery is heated when the battery state of charge is larger than a set threshold and the detected battery temperature is lower than a battery shutdown heating start threshold.

7. The battery self-awakening heating method according to claim 3 or 5, wherein the energy which can be converted into the vehicle power by the battery is obtained according to the available energy variation of the battery, the required heating electric quantity of the battery and the added heat dissipation energy of the battery when the temperature of the battery rises for a set number of degrees.

8. The battery self-awakening heating method according to any one of claims 2-5, wherein the value range of the dynamic performance coefficient is 0.6-1.4.

9. The battery self-awakening heating method according to claim 4 or 5, wherein the electric braking coefficient of performance ranges from 0.6 to 1.4.

10. An electric vehicle comprising a power battery and a battery self-wake-up heating device, wherein the battery self-wake-up heating device comprises a processor and a memory, the processor executing a computer program stored by the memory to implement the battery self-wake-up heating method according to any one of claims 1-9.

Technical Field

The invention relates to an electric automobile and a battery self-awakening heating method thereof, and belongs to the technical field of new energy electric automobiles.

Background

Under the low temperature environment, when the vehicle is restarted after being parked for a long time, the battery temperature is lower, the charging and discharging power of the battery is reduced, the dynamic property of the vehicle is reduced, even the vehicle can not run, the kinetic energy recovery of the vehicle is influenced, the electric braking effect is influenced, and the charging time is prolonged.

At present, the above problems are generally solved by heating a battery to avoid the temperature of the battery from being too low, and the existing heating methods of low-temperature parking batteries are all fixed threshold value type heating methods, for example, an active thermal management control method of an electric vehicle disclosed in the chinese patent application with application publication No. CN109532562A, the method sets bus wake-up time according to the ambient temperature, heats the battery when the detected temperature of a battery core is not more than-10 ℃ and the charge state of the battery is not less than 30%, and then stops heating when the temperature of the battery core is raised to 0 ℃. The method adopts a fixed heating opening threshold value and a heating closing threshold value, although the method is simple, the method adopts the fixed and unchangeable threshold value in any situation, the adjustment cannot be made according to the actual requirement of a driver on the vehicle performance, if the set heating opening threshold value is too high, the vehicle can be heated frequently under the condition that the requirement of the driver on the vehicle performance is low, and the energy waste is caused; if the set heating start threshold is too low, it may not be guaranteed that the battery temperature can meet the expected demand of the driver for the vehicle performance when the vehicle is used.

Disclosure of Invention

The invention aims to provide an electric automobile and a battery self-awakening heating method thereof, which are used for solving the problem that the battery is poor in heating effect by using the conventional battery heating method during low-temperature parking.

In order to achieve the above object, the present invention provides a battery self-awakening heating method, which comprises the following steps:

(1) when the vehicle is in a parking state, periodically detecting the temperature of the battery according to a set self-awakening frequency;

(2) judging whether the detected battery temperature is lower than a battery shutdown heating starting threshold or not, if so, heating the battery, judging whether the temperature of the battery reaches the battery shutdown heating closing threshold or not in the heating process, and if so, stopping heating the battery;

the method comprises the steps of determining a battery parking heating starting threshold according to a battery driving heating starting temperature before a vehicle stops, and further determining a battery parking heating stopping threshold, wherein the battery driving heating starting temperature is used for judging whether to heat a battery when the vehicle is in a driving state.

The invention also provides an electric automobile which comprises a power battery and a battery self-awakening heating device, wherein the battery self-awakening heating device comprises a processor and a memory, and the processor executes a computer program stored by the memory so as to realize the battery self-awakening heating method.

The electric automobile and the battery self-awakening heating method thereof have the beneficial effects that: because the battery driving heating starting temperature is used for judging whether the battery is heated when the vehicle is in a driving state, the temperature reflects the requirement of a driver on the performance of the vehicle in the driving process, the battery parking heating starting threshold value is associated with the battery driving heating starting temperature before the vehicle is parked, the requirement of the driver on the performance of the vehicle in the driving process before the vehicle is parked can be added into the battery parking heating starting threshold value, the battery is heated when the vehicle is parked according to the threshold value, the requirement of the driver on the performance of the vehicle can be met by the heated battery temperature, and the battery heating effect is good.

Further, in the electric vehicle and the battery self-awakening heating method thereof, the calculation process of the battery driving heating starting temperature before the vehicle stops includes:

obtaining expected maximum discharge current according to the maximum discharge current and the power performance coefficient output by the battery in a control period before the vehicle stops;

obtaining the temperature corresponding to the expected maximum discharge current as a first expected temperature according to the corresponding relation between the predetermined battery charge-discharge current and the temperature and the expected maximum discharge current;

and obtaining the heating starting temperature of the battery running vehicle before the vehicle stops according to the first expected temperature.

The beneficial effects of doing so are: the factors of 3 aspects are comprehensively considered when the heating starting temperature of the battery for driving before the vehicle stops is calculated, correspondingly, the factors of 3 aspects are also comprehensively considered when the heating starting temperature of the battery for stopping is set, the factor 1 is the maximum discharge current output by the battery in a control period, and the value can change along with the actual driving working condition of the vehicle, so that the influence of the actual power output condition of the vehicle on the threshold setting can be reflected by the factor; factor 2 is a power performance coefficient, which can be set according to the specific requirements of the customer on the vehicle dynamic performance, so that the factor can reflect the influence of the customer requirements on the threshold setting; the factor 3 is a predetermined corresponding relation between the charging and discharging current and the temperature of the battery, and the corresponding relation can change along with the change of the model of the battery, so the factor can reflect the influence of the model of the battery on the setting of the threshold; in conclusion, the battery parking heating starting threshold value comprehensively considers the actual power output condition of the vehicle, the power demand of the customer on the vehicle and 3 factors of the battery models, and the battery heating control is carried out by utilizing the battery parking heating starting threshold value, so that the heated battery temperature can meet the actual power demand of the vehicle and the special demand of the customer on the power of the vehicle, the battery parking heating starting threshold value can be suitable for batteries of different models, and the application range is wider.

Further, in the electric vehicle and the battery self-awakening heating method thereof, the first expected temperature is adjusted, and the adjusted first expected temperature is used as a battery driving heating starting temperature before the vehicle stops; wherein the following steps are iteratively performed to adjust the first desired temperature: on the basis of the first expected temperature, when the energy of the battery, which can be converted into the vehicle power, is more than zero after the first set degree is increased, the first expected temperature is added with the first set degree until the energy of the battery, which can be converted into the vehicle power, is less than or equal to zero after the first set degree is increased, and the adjusted first expected temperature is obtained.

The beneficial effects of doing so are: on the basis of first expected temperature, if continue to improve the battery temperature and be favorable to converting the electric quantity of battery into vehicle power, just heighten first expected temperature to battery driving heating opening temperature before the vehicle parks as the vehicle with first expected temperature after will heightening, further considered the influence of economic nature when making the setting battery park the heating opening threshold value, utilize this battery to park the heating opening threshold value and carry out battery heating control, be favorable to taking into account vehicle power nature and economic nature simultaneously.

Further, in the electric vehicle and the battery self-awakening heating method thereof, the calculation process of the battery driving heating starting temperature before the vehicle stops further includes:

obtaining expected maximum charging current according to the maximum charging current output by the battery in a control period before the vehicle stops and the electric braking performance coefficient;

obtaining the temperature corresponding to the expected maximum charging current as a second expected temperature according to the corresponding relation between the predetermined battery charging and discharging current and the temperature and the expected maximum charging current;

comparing the first expected temperature with the second expected temperature, and taking the maximum value as the final expected temperature;

and obtaining the heating starting temperature of the battery running vehicle before the vehicle stops according to the final expected temperature.

The beneficial effects of doing so are: when the heating starting temperature of the battery before the vehicle stops is calculated, the factors of the 2 aspects are increased, and correspondingly, the factors of the 2 aspects, namely the maximum charging current output by the battery in the control period and the electric brake performance coefficient are increased when the heating starting temperature of the battery during the vehicle stops. The maximum charging current output by the battery in the control period can change along with the actual driving working condition of the vehicle, and the factor reflects the influence of the actual electric braking condition of the vehicle on the threshold value setting; the electric braking performance coefficient can be set according to the specific requirements of a customer on the electric braking effect of the vehicle, the influence of the customer demand on the threshold value setting is reflected by the factor, the battery heating control is carried out by utilizing the battery stopping heating starting threshold value, and the vehicle dynamic property and the electric braking effect are favorably considered at the same time.

Further, in the electric vehicle and the battery self-awakening heating method thereof, the final expected temperature is adjusted, and the adjusted final expected temperature is used as the battery driving heating starting temperature before the vehicle stops; wherein the following steps are iteratively performed to adjust the final desired temperature: on the basis of the final expected temperature, when the energy which can be converted into the vehicle power by the battery is more than zero after the second set degree is increased, the final expected temperature is added with the second set degree until the energy which can be converted into the vehicle power by the battery is less than or equal to zero after the second set degree is increased, and the adjusted final expected temperature is obtained.

The beneficial effects of doing so are: on the basis of the final expected temperature, if the battery temperature is continuously increased to be beneficial to converting the electric quantity of the battery into the vehicle power, the final expected temperature is increased, and the increased final expected temperature is used as the battery driving heating starting temperature before the vehicle stops, so that the influence of economy is further considered when the battery stopping heating starting threshold is set, the battery stopping heating starting threshold is utilized to carry out battery heating control, and the vehicle power, the electric braking effect and the economy are simultaneously considered.

Further, in the electric vehicle and the battery self-awakening heating method thereof, the battery charge state is periodically detected according to a set self-awakening frequency, and when the battery charge state is greater than a set threshold and the detected battery temperature is lower than a battery shutdown heating start threshold, the battery is heated.

The beneficial effects of doing so are: the battery temperature and the battery charge state are detected simultaneously, when the battery charge state is larger than a set threshold value and the detected battery temperature is lower than a battery stopping heating starting threshold value, the battery is heated, the battery can be guaranteed to be heated under the condition that the battery is not lack of electricity, and the battery is protected.

Further, in the electric vehicle and the battery self-awakening heating method thereof, when the energy which can be converted into the vehicle power by the battery is set according to the temperature of the battery, the available energy variable of the battery, the heating electric quantity required by the battery and the heat dissipation energy added by the battery are obtained.

Further, in the electric vehicle and the battery self-awakening heating method thereof, the value range of the power performance coefficient is 0.6-1.4.

Further, in the electric vehicle and the battery self-awakening heating method thereof, the numeric area of the electric braking performance coefficient is 0.6-1.4.

Drawings

Fig. 1 is a schematic structural view of an electric vehicle in embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a battery self-wake-up heating device in embodiment 1 of the present invention;

fig. 3 is a flowchart of a threshold value determination process in embodiment 1 of the present invention;

fig. 4 is a schematic structural view of an electric vehicle in embodiment 2 of the invention;

fig. 5 is a flowchart of a threshold value determination process in embodiment 2 of the present invention;

fig. 6 is a flowchart of a threshold value determination process in embodiment 3 of the present invention.

Detailed Description

Embodiment mode 1

Embodiment 1 relates to an electric vehicle embodiment and a battery self-wake-up heating method embodiment.

As shown in fig. 1, the electric vehicle of the present embodiment includes a power battery, a Battery Management System (BMS), a power coefficient of performance input device, a self-wake-up frequency input device, a battery self-wake-up heating device, and a battery heating apparatus.

The BMS has a DC/DC with a regular self-awakening function, after the BMS is normally powered down, the high voltage of the DC/DC is in a connection state, the BMS has a function of regularly (determined according to the self-awakening frequency) outputting 24V, after the BMS is output with 24V, the BMS is awakened to be in a working state, and the battery temperature, voltage, charge state and the like can be collected and monitored. The DC/DC can also supply power to the vehicle control unit and the monitoring host, so that monitoring data can be stored in time and uploaded to a background monitoring system, and records can be consulted conveniently.

In the running process of the vehicle, the BMS monitors the charging and discharging current output by the power battery in real time, and sends the maximum discharging current output by the battery in a control period (for example, 30 minutes, which can be specifically set according to actual requirements) before the vehicle stops to the battery self-awakening heating device; a vehicle driver inputs a power performance coefficient through a power performance coefficient input device, and the power performance coefficient input device sends the power performance coefficient input by the driver to a battery self-awakening heating device; the vehicle driver inputs the self-awakening frequency through the self-awakening frequency input device, and the self-awakening frequency input device sends the self-awakening frequency input by the driver to the battery self-awakening heating device; when the vehicle is in a parking state, the battery self-awakening heating device awakens the BMS according to the received self-awakening frequency, detects the battery temperature and the battery charge state after the BMS is awakened, and sends the detected battery temperature and the detected battery charge state to the battery self-awakening heating device; the battery self-awakening heating device processes the received maximum discharge current output by the battery in a control period before the vehicle stops, the power performance coefficient, the detected battery temperature and the battery charge state so as to realize the battery self-awakening heating method of the embodiment and further control the heating or the heating stop of the battery; the battery heating equipment is responsible for heating the power battery, and the heating mode is not limited to resistor disc heating, liquid heating or current oscillation heating and the like.

In the present embodiment, the coefficient of power performance input device is a mechanical switch with different gears, each gear corresponds to a coefficient of power performance, and specifically, as shown in table 1, the larger the coefficient of power performance, the higher the requirement of the driver on the dynamic performance of the vehicle.

TABLE 1 Gear and Power Performance coefficient mapping Table

Gear position	1	2	3	4	5
						Coefficient of dynamic performance	0.6	0.8	1	1.2	1.4

The self-wake-up frequency input device is also a mechanical switch with different gears, each gear corresponds to a self-wake-up frequency, and the self-wake-up frequency input device is specifically shown in table 2:

TABLE 2 Gear and SELF-WAKE FREQUENCY CORRESPONDING TABLE

Gear position	1	2	3	4	5
						Self-wakeup frequency	0.6x	0.8x	x	1.2x	1.4x

The value of the base value x of the self-wakeup frequency in table 2 is set according to actual needs. The setting of the base value x of the self-wake-up frequency is based on the following: according to the temperature in a one-year period, the vehicle running environment is divided into regions such as a severe cold region, a warm region, a hot region and the like, and different x values are set in different regions. If the Beijing area belongs to a cold area, the temperature of the battery is generally maintained in a stable range when the vehicle normally operates in the daytime, the temperature of the battery is obviously reduced when the vehicle is parked at night, and the lowest temperature of the battery which is parked for 3 hours is generally reduced to be below a heating starting threshold value for parking the battery, so that the value x can be set by starting heating once every 3 hours.

As other embodiments, the power performance coefficient input device can also be a keyboard or a touch screen, and the like, a driver can directly and manually input any numerical value in the value range of the power performance coefficient, and the value range of the power performance coefficient is 0.6-1.4; the self-awakening frequency input device can also be a keyboard or a touch screen, and the driver can directly and manually input the self-awakening frequency.

In this embodiment, the dynamics coefficient input device and the self-awakening frequency input device are provided separately, and as another embodiment, these two devices may be combined into one device.

As shown in fig. 2, the battery self-wake-up heating device of the present embodiment includes a processor and a memory, and the processor executes a computer program stored in the memory to implement the battery self-wake-up heating method of the present embodiment.

The processor refers to a processing device such as a microprocessor MCU or a programmable logic device FPGA. The memory includes a physical device for storing information, and generally, information is digitized and then stored in a medium using an electric, magnetic, optical, or the like. For example: various memories for storing information by using an electric energy mode, such as RAM, ROM and the like; various memories for storing information by magnetic energy, such as hard disk, floppy disk, magnetic tape, magnetic core memory, bubble memory, and U disk; various types of memory, CD or DVD, that store information optically. Of course, there are other ways of memory, such as quantum memory, graphene memory, and so forth.

The battery self-wake-up heating method according to the present embodiment is described below, and the battery self-wake-up heating method may form a computer program that is stored in a memory and called when a processor runs, so as to implement the battery self-wake-up heating method. The method specifically comprises the following steps:

(1) when the vehicle is in a parking state, periodically detecting the temperature and the charge state of the battery according to a set self-awakening frequency;

(2) when the state of charge of the battery is larger than a set threshold (for example, 30%, specifically set according to actual needs) and the detected battery temperature is lower than a battery shutdown heating start threshold, heating the battery, judging whether the temperature of the battery reaches the battery shutdown heating stop threshold in the heating process, and if so, stopping heating the battery;

the heating starting temperature of the battery during the vehicle running is used for judging whether to heat the battery when the vehicle is in a running state.

In this embodiment, the determination process of the battery shutdown heating-on threshold and the battery shutdown heating-off threshold is as shown in fig. 3:

1) obtaining expected maximum discharge current according to the maximum discharge current and the power performance coefficient output by the battery in a control period before the vehicle stops; the desired maximum discharge current is equal to the power performance coefficient × the maximum discharge current output from the battery.

2) Obtaining a temperature corresponding to the expected maximum discharge current as a first expected temperature by inquiring a battery charge-discharge current limit table; each type of battery has a respective battery charging and discharging current limit table, the table is the corresponding relation among the battery charging and discharging current, the battery temperature and the battery charge state, the corresponding relation can be obtained through experiments or a simulation mode, and therefore the corresponding relation between the battery charging and discharging current and the battery temperature can be obtained from the battery charging and discharging current limit table; as another embodiment, the correspondence relationship between the battery charge/discharge current and the temperature may also be directly expressed in the form of a function, a curve, or the like, and is not limited to the one obtained from the battery charge/discharge current limit table.

3) Adjusting the first expected temperature, and taking the adjusted first expected temperature as a battery running heating starting temperature before the vehicle stops; specifically, the following steps are iteratively performed to adjust the first desired temperature: on the basis of the first expected temperature, when the energy of the battery, which can be converted into the vehicle power, is greater than zero after 1 ℃ is increased (namely a first set degree which can be adjusted according to actual needs), the first expected temperature is added with 1 ℃ until the energy of the battery, which can be converted into the vehicle power, is less than or equal to zero after the 1 ℃ is increased, and the adjusted first expected temperature is obtained.

For example, if the first desired temperature obtained in step 2) is 3 ℃, it is determined whether the energy that the battery can convert into vehicle power is greater than zero when the battery temperature is 3 ℃, and if so, it indicates that the battery temperature is increased to be beneficial for converting the electric quantity of the battery into vehicle power, i.e., the battery temperature is increased to be beneficial for improving the economy of the vehicle, at this time, 1 ℃ is added to the first desired temperature, and it is continuously determined whether the energy that the battery can convert into vehicle power is greater than zero when the battery temperature is 4 ℃ when the battery temperature is + 3 ℃ +1 ℃ + 4 ℃, and if so, it indicates that the battery temperature is increased to be not beneficial for improving the economy of the vehicle, and then the adjusted first desired temperature is 4 ℃.

The energy Q0 converted from the battery into the vehicle power is obtained according to the available energy variable Q1 of the battery, the required heating electric quantity Q2 of the battery and the increased heat dissipation energy Q3 of the battery when the temperature of the battery rises by 1 ℃ (namely, the set degree, and the value can be adjusted according to actual needs), wherein Q0 is Q1-Q2-Q3. If Q0 is greater than 0, it indicates that the battery temperature is increased to facilitate converting the battery charge into vehicle power, i.e. the increased battery temperature is beneficial to improve the vehicle economy; if Q0 < 0, it indicates that an increase in battery temperature is not favorable for improving vehicle economy. Wherein, Q1 can be obtained by inquiring the temperature-available energy MAP table of the power battery; q2 can be obtained by heating experimental data of batteries of different types, and the value is mainly influenced by the specific heat capacity and the heat conductivity of the battery, for example, when a certain type of battery is heated, the temperature rises by 1 ℃ every time, and the consumed electric quantity is 0.5 kWh; q3 is the amount of heat dissipation energy increase of the battery every 1 ℃ when the battery rises corresponding to the ambient temperature of the battery in each control period, and the value is mainly influenced by the heat preservation performance of the battery and the temperature difference between the battery and the environment, and can be obtained through experimental data, for example, the battery temperature of a certain type of battery is 2 ℃ when the ambient temperature is-10 ℃, the temperature rise of the battery is 1 ℃, the temperature difference is increased from 12 ℃ to 13 ℃, the heat dissipation energy increase is 0.1kWh in the control period, and the like.

4) Determining a battery parking heating starting threshold according to the battery driving heating starting temperature before the vehicle stops; the battery parking heating starting threshold value is equal to the battery driving heating starting temperature before the vehicle is parked plus a temperature correction coefficient, the temperature correction coefficient comprehensively considers the vehicle dynamic property and economic property setting, and the value is generally 0; in another embodiment, the battery stop heating start threshold may be equal to a battery running heating start temperature before the vehicle stops.

5) Obtaining a battery shutdown heating closing threshold according to the battery shutdown heating opening threshold and the threshold correction coefficient; and the battery stopping heating closing threshold value is equal to the battery stopping heating opening threshold value plus the threshold value correction coefficient.

The threshold correction coefficient is set according to actual needs, as long as the difference between the battery shutdown heating start threshold and the battery shutdown heating stop threshold (hereinafter referred to as the difference between the start threshold and the stop threshold) is greater than the accuracy of the temperature sensor of the electric vehicle battery system, and generally, the difference between the start threshold and the stop threshold is preferably not less than twice the detection accuracy of the temperature sensor, so as to prevent the heating from being frequently started and closed due to detection errors of the temperature sensor, and the service life of the electric vehicle battery heating system is not affected. The threshold correction factor is typically an integer, such as 2 ℃ or 4 ℃.

The battery self-awakening heating method of the embodiment has the following advantages:

(1) the battery temperature and the battery charge state are detected simultaneously, and when the battery charge state is greater than a set threshold and the detected battery temperature is lower than a battery parking heating starting threshold, the battery is heated, so that the battery can be heated under the condition that the battery is not in power shortage, and the battery is protected;

(2) when the vehicle is parked, the BMS is awakened periodically to detect the temperature and the charge state of the battery, and the battery is heated according to a preset strategy, so that the temperature of the battery can be kept in a reasonable range all the time, and the vehicle performance can meet the expected requirement when a driver uses the vehicle;

(3) the battery driving heating starting temperature is used for judging whether the battery is heated or not when the vehicle is in a driving state, and the temperature reflects the requirement of a driver on the performance of the vehicle in the driving process, so that the battery parking heating starting threshold is associated with the battery driving heating starting temperature before the vehicle is parked, the requirement of the driver on the performance of the vehicle in the driving process before the vehicle is parked can be added into the battery parking heating starting threshold, the battery is heated in the parking process according to the threshold, the requirement of the driver on the performance of the vehicle can be met by the heated battery temperature, and the battery heating effect is good;

(4) 4 factors are comprehensively considered when the heating starting temperature of the battery before the vehicle stops is calculated, correspondingly, the 4 factors are also comprehensively considered when the heating starting temperature of the battery after the vehicle stops, the factor 1 is the maximum discharge current output by the battery in a control period, and the value can change along with the actual driving working condition of the vehicle, so that the influence of the actual power output condition of the vehicle on the threshold setting can be reflected by the factor; factor 2 is a power performance coefficient, which can be set according to the specific requirements of the customer on the vehicle dynamic performance, so that the factor can reflect the influence of the customer requirements on the threshold setting; the factor 3 is a predetermined corresponding relation between the charging and discharging current and the temperature of the battery, and the corresponding relation can change along with the change of the model of the battery, so the factor can reflect the influence of the model of the battery on the setting of the threshold; the factor 4 is the energy that the battery can convert into the vehicle power, and the value can reflect whether the increase of the battery temperature is beneficial to converting the electric quantity of the battery into the vehicle power, namely whether the increase of the battery temperature is beneficial to improving the vehicle economy, so that the factor can reflect the influence of the vehicle economy on the threshold value setting; in conclusion, the battery parking heating starting threshold value comprehensively considers 4 factors of the actual power output condition of the vehicle, the power demand of the customer on the vehicle and the vehicle economy, and the battery heating control is carried out by utilizing the battery parking heating starting threshold value, so that the temperature of the heated battery can meet the actual power demand of the vehicle and the special demand of the customer on the power of the vehicle, the battery can be suitable for batteries of different models, the application range is wider, and the power and the economy of the vehicle can be considered at the same time.

As another embodiment, the battery driving heating start temperature before the vehicle stops may be determined by other methods in the prior art.

As another embodiment, only the battery temperature may be detected, and the battery may be heated when the detected battery temperature is lower than the battery stop heating on threshold.

As another embodiment, the threshold determination process may omit step 3), and directly use the first desired temperature obtained in step 2) as the battery driving heating start temperature before the vehicle stops.

In the embodiment, the value range of the power performance coefficient is 0.6-1.4, and the expected maximum discharge current is equal to the power performance coefficient multiplied by the maximum discharge current output by the battery; as another embodiment, the value range of the power performance coefficient may also be adjusted according to actual needs, and the expected maximum discharge current may also be equal to the power performance coefficient plus the maximum discharge current output by the battery. In addition, the battery shutdown heating shutdown threshold value can also be equal to the battery shutdown heating startup threshold value multiplied by a threshold correction coefficient, the threshold correction coefficient is set according to actual needs, and only the difference value between the battery shutdown heating startup threshold value and the battery shutdown heating shutdown threshold value is ensured to be larger than the accuracy of the temperature sensor of the battery system of the electric automobile.

In another embodiment, the maximum discharge current of the battery in the control period may be obtained by the BMS sending the battery discharge current in the control period to the battery self-awakening heating device and processing the battery self-awakening heating device.

Embodiment 2:

embodiment 2 relates to an electric vehicle embodiment and a battery self-wake-up heating method embodiment.

As shown in fig. 4, the electric vehicle according to the present embodiment differs from embodiment 1 in that: firstly, an electric braking performance coefficient input device is added to the electric automobile, a vehicle driver inputs an electric braking performance coefficient through the electric braking performance coefficient input device, and the electric braking performance coefficient input device sends the electric braking performance coefficient input by the driver to a battery self-awakening heating device; secondly, the BMS of the electric automobile also sends the maximum charging current output by the battery in a control period before the vehicle stops to the battery self-awakening heating device; finally, the battery self-awakening heating device processes the received maximum discharging current and maximum charging current output by the battery in a control period before the vehicle stops, the power performance coefficient, the electric braking performance coefficient, the detected battery temperature and the battery charge state so as to realize the battery self-awakening heating method of the embodiment and further control the heating or stopping of the heating of the battery.

In this embodiment, the electric brake coefficient of performance input device is a mechanical switch with different gears, each gear corresponds to one electric brake coefficient of performance, and specifically, as shown in table 3, the larger the electric brake coefficient of performance, the higher the requirement of the driver on the electric braking effect of the vehicle.

TABLE 3 Gear and electric brake performance coefficient corresponding table

Gear position	1	2	3	4	5
						Coefficient of performance of electric brake	0.6	0.8	1	1.2	1.4

As other embodiments, the electric braking performance coefficient input device may also be a keyboard or a touch screen, and a driver may directly and manually input any value within a value range of the electric braking performance coefficient, where the value range of the electric braking performance coefficient is 0.6-1.4.

In this embodiment, the dynamic coefficient input device, the electric brake performance coefficient input device, and the self-awakening frequency input device are provided separately, and as another embodiment, these three devices may be combined into one device.

The following describes a battery self-wake-up heating method according to the present embodiment, which includes the following steps:

(1) when the vehicle is in a parking state, periodically detecting the temperature and the charge state of the battery according to a set self-awakening frequency;

(2) when the state of charge of the battery is larger than a set threshold (for example, 30%, specifically set according to actual needs) and the detected battery temperature is lower than a battery shutdown heating start threshold, heating the battery, judging whether the temperature of the battery reaches the battery shutdown heating stop threshold in the heating process, and if so, stopping heating the battery;

the heating starting temperature of the battery during the vehicle running is used for judging whether to heat the battery when the vehicle is in a running state.

In this embodiment, the determination process of the battery shutdown heating-on threshold and the battery shutdown heating-off threshold is shown in fig. 5:

1) obtaining expected maximum discharge current according to the maximum discharge current and the power performance coefficient output by the battery in a control period before the vehicle stops; the desired maximum discharge current is equal to the power performance coefficient × the maximum discharge current output from the battery.

2) Obtaining a temperature corresponding to the expected maximum discharge current as a first expected temperature by inquiring a battery charge-discharge current limit table;

3) obtaining expected maximum charging current according to the maximum charging current output by the battery in a control period before the vehicle stops and the electric braking performance coefficient; the desired maximum charging current is equal to the electric brake performance coefficient × the maximum charging current output by the battery.

4) Obtaining the temperature corresponding to the expected maximum charging current as a second expected temperature by inquiring a battery charging and discharging current limit table;

5) comparing the first expected temperature with the second expected temperature, and taking the maximum value as the final expected temperature;

6) taking the final expected temperature as the heating starting temperature of the battery running vehicle before the vehicle stops;

7) determining a battery parking heating starting threshold according to the battery driving heating starting temperature before the vehicle stops; the battery parking heating starting threshold value is equal to the battery driving heating starting temperature before the vehicle is parked plus a temperature correction coefficient, the temperature correction coefficient comprehensively considers the vehicle dynamic property and economic property setting, and the value is generally 0; in another embodiment, the battery stop heating start threshold may be equal to a battery running heating start temperature before the vehicle stops.

8) Obtaining a battery shutdown heating closing threshold according to the battery shutdown heating opening threshold and the threshold correction coefficient; and the battery stopping heating closing threshold value is equal to the battery stopping heating opening threshold value plus the threshold value correction coefficient.

The threshold correction coefficient is set according to actual needs, as long as the difference between the battery shutdown heating start threshold and the battery shutdown heating stop threshold (hereinafter referred to as the difference between the start threshold and the stop threshold) is greater than the accuracy of the temperature sensor of the electric vehicle battery system, and generally, the difference between the start threshold and the stop threshold is preferably not less than twice the detection accuracy of the temperature sensor, so as to prevent the heating from being frequently started and closed due to detection errors of the temperature sensor, and the service life of the electric vehicle battery heating system is not affected. The threshold correction factor is typically an integer, such as 2 ℃ or 4 ℃.

The battery self-awakening heating method comprehensively considers factors in the aspect of 5 when calculating the heating starting temperature of the battery running before the vehicle stops, wherein the factor 1 is the maximum discharge current output by the battery in the control period, and the value can change along with the actual running working condition of the vehicle, so that the factor can reflect the influence of the actual power output condition of the vehicle on the threshold value setting; factor 2 is a power performance coefficient, which can be set according to the specific requirements of the customer on the vehicle dynamic performance, so that the factor can reflect the influence of the customer requirements on the threshold setting; the factor 3 is a predetermined corresponding relation between the charging and discharging current and the temperature of the battery, and the corresponding relation can change along with the change of the model of the battery, so the factor can reflect the influence of the model of the battery on the setting of the threshold; the factor 4 is the maximum charging current output by the battery in the control period, the value can change along with the actual driving working condition of the vehicle, and the factor reflects the influence of the actual electric braking condition of the vehicle on the threshold value setting; factor 5 is an electric braking performance coefficient, which can be set according to the specific requirements of a customer on the electric braking effect of the vehicle, and reflects the influence of the customer requirements on the threshold setting; in conclusion, the battery parking heating starting threshold value comprehensively considers the actual power output condition and the actual electric braking condition of the vehicle, the requirements of customers on the dynamic property and the electric braking effect of the vehicle and 5 factors of the battery model, the battery parking heating starting threshold value is utilized to carry out battery heating control, the temperature of the heated battery can be ensured to meet the special requirements of the actual dynamic property of the vehicle and the customers on the dynamic property of the vehicle, the actual electric braking property of the vehicle and the special requirements of the customers on the electric braking effect of the vehicle can be met, meanwhile, the battery parking heating starting threshold value can be suitable for batteries of different models, and the application range is wider.

Embodiment 3:

embodiment 3 relates to an electric vehicle embodiment and a battery self-wake-up heating method embodiment.

The electric vehicle of the present embodiment has the same configuration as embodiment 2, except for the following: the battery self-awakening heating method that can be realized by the battery self-awakening heating device in the electric vehicle according to the present embodiment is different from that in embodiment 2.

The following describes a battery self-wake-up heating method according to the present embodiment, which includes the following steps:

(1) when the vehicle is in a parking state, periodically detecting the temperature and the charge state of the battery according to a set self-awakening frequency;

(2) when the state of charge of the battery is larger than a set threshold (for example, 30%, specifically set according to actual needs) and the detected battery temperature is lower than a battery shutdown heating start threshold, heating the battery, judging whether the temperature of the battery reaches the battery shutdown heating stop threshold in the heating process, and if so, stopping heating the battery;

the heating starting temperature of the battery during the vehicle running is used for judging whether to heat the battery when the vehicle is in a running state.

In this embodiment, the determination process of the battery shutdown heating-on threshold and the battery shutdown heating-off threshold is as shown in fig. 6:

1) obtaining expected maximum discharge current according to the maximum discharge current and the power performance coefficient output by the battery in a control period before the vehicle stops; the desired maximum discharge current is equal to the power performance coefficient × the maximum discharge current output from the battery.

2) Obtaining a temperature corresponding to the expected maximum discharge current as a first expected temperature by inquiring a battery charge-discharge current limit table;

3) obtaining expected maximum charging current according to the maximum charging current output by the battery in a control period before the vehicle stops and the electric braking performance coefficient; the desired maximum charging current is equal to the electric brake performance coefficient × the maximum charging current output by the battery.

4) Obtaining the temperature corresponding to the expected maximum charging current as a second expected temperature by inquiring a battery charging and discharging current limit table;

5) comparing the first expected temperature with the second expected temperature, and taking the maximum value as the final expected temperature;

6) adjusting the final expected temperature, and taking the adjusted final expected temperature as the heating starting temperature of the battery running vehicle before the vehicle stops; specifically, the following steps are iteratively performed to adjust the final desired temperature: on the basis of the final expected temperature, when the energy which can be converted into the vehicle power by the battery is more than zero after 1 ℃ is increased (namely a second set degree which can be adjusted according to actual needs), the final expected temperature is added with 1 ℃ until the energy which can be converted into the vehicle power by the battery is less than or equal to zero after the 1 ℃ is increased, and the adjusted final expected temperature is obtained.

7) Determining a battery parking heating starting threshold according to the battery driving heating starting temperature before the vehicle stops; the battery parking heating starting threshold value is equal to the battery driving heating starting temperature before the vehicle is parked plus a temperature correction coefficient, the temperature correction coefficient comprehensively considers the vehicle dynamic property and economic property setting, and the value is generally 0; in another embodiment, the battery stop heating start threshold may be equal to a battery running heating start temperature before the vehicle stops.

8) Obtaining a battery shutdown heating closing threshold according to the battery shutdown heating opening threshold and the threshold correction coefficient; and the battery stopping heating closing threshold value is equal to the battery stopping heating opening threshold value plus the threshold value correction coefficient.

The threshold correction coefficient is set according to actual needs, as long as the difference between the battery shutdown heating start threshold and the battery shutdown heating stop threshold (hereinafter referred to as the difference between the start threshold and the stop threshold) is greater than the accuracy of the temperature sensor of the electric vehicle battery system, and generally, the difference between the start threshold and the stop threshold is preferably not less than twice the detection accuracy of the temperature sensor, so as to prevent the heating from being frequently started and closed due to detection errors of the temperature sensor, and the service life of the electric vehicle battery heating system is not affected. The threshold correction factor is typically an integer, such as 2 ℃ or 4 ℃.

The difference between the battery self-awakening heating method of the embodiment and the embodiment 2 is that when the battery driving heating start temperature before the vehicle stops is calculated, the final expected temperature is adjusted, if the battery temperature is continuously increased on the basis of the final expected temperature to be beneficial to converting the electric quantity of the battery into the vehicle power, the final expected temperature is increased, and the increased final expected temperature is used as the battery driving heating start temperature before the vehicle stops, so that the influence of economy is further considered when the battery stopping heating start threshold is set, the battery stopping heating start threshold is utilized to carry out battery heating control, and the vehicle power, the electric braking effect and the economy are favorably considered at the same time.