Heating method and heating device for battery system of electric vehicle

Abstract

The invention relates to a heating method and a heating device for a battery system of an electric vehicle. A heating method for a battery system of an electric vehicle belongs to the technical field of electric vehicles and comprises the following steps: acquiring a heating power demand instruction sent by a vehicle control unit; based on the heating power, the lower limit of the heating power and the upper limit of the heating power for heating the battery system in the current state of the electric vehicle, determining the actual heating power for heating the battery system in the current state of the electric vehicle; based on the actual heating power, the bus voltage of the electric vehicle in the current state and the rotating speed of the asynchronous driving motor, determining a target exciting current which needs to be output by the asynchronous driving motor when the battery system is heated in the current state of the electric vehicle in a current look-up table; and the asynchronous driving motor is controlled to work with the target excitation current, loss corresponding to the target excitation current is output, and cooling water circulation heating is conducted on a battery system of the electric vehicle based on the loss.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electric vehicles, and in particular to a method for heating an electric vehicle battery system, a heating device for an electric vehicle battery system, a storage medium, and an electric vehicle. Background Art

[0002] Electric vehicles are becoming increasingly popular in today's society and have become the future development direction of the automotive industry. Electric vehicles are powered by power batteries. Low temperatures significantly affect the battery's charging and discharging processes, significantly reducing the vehicle's driving range. Therefore, in low-temperature environments, power battery heating is necessary to improve the battery's charging and discharging performance and increase driving range. Summary of the Invention

[0003] In view of this, the embodiments of the present disclosure are intended to provide an electric vehicle battery system heating method, an electric vehicle battery system heating device, a storage medium, and an electric vehicle.

[0004] The technical solution of the present disclosure is achieved as follows:

[0005] In a first aspect, the present disclosure provides a method for heating a battery system of an electric vehicle.

[0006] The electric vehicle battery system heating method provided by the embodiment of the present disclosure includes:

[0007] Obtaining a heating power demand instruction sent by a vehicle controller; wherein the heating power demand instruction includes the heating power required to heat the battery system in the current state of the electric vehicle;

[0008] Determining a lower limit of heating power based on the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle, and determining an upper limit of heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature in the current state of the electric vehicle;

[0009] determining an actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required for heating the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit;

[0010] Based on the actual heating power, the bus voltage of the electric vehicle in the current state, and the speed of the asynchronous drive motor, determining in a current lookup table a target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle;

[0011] The asynchronous drive motor is controlled to operate at the target excitation current, and a loss corresponding to the target excitation current is output, so as to perform cooling water circulation heating on the battery system of the electric vehicle based on the loss.

[0012] In some embodiments, before determining in the current lookup table the target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle, the method includes:

[0013] Determine N voltage points according to the battery operating range; the N voltage points cover the maximum voltage and the minimum voltage of the battery;

[0014] The relationship among the heating power output by the drive system under the bus voltage, the rotational speed of the asynchronous drive motor and the excitation current output by the asynchronous drive motor is calibrated based on the N voltage points to obtain the current lookup table.

[0015] In some embodiments, determining the actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit includes:

[0016] If the heating power required for heating the battery system in the current state of the electric vehicle is between the lower limit of the heating power and the upper limit of the heating power, then determining that the heating power required for heating the battery system in the current state of the electric vehicle is the actual heating power for heating the battery system in the current state of the electric vehicle;

[0017] If the heating power required to heat the battery system in the current state of the electric vehicle is less than the heating power lower limit, determining the heating power lower limit as the actual heating power required to heat the battery system in the current state of the electric vehicle;

[0018] If the heating power required to heat the battery system in the current state of the electric vehicle is greater than the heating power upper limit, the heating power upper limit is determined to be the actual heating power required to heat the battery system in the current state of the electric vehicle.

[0019] In some embodiments, determining the actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit includes:

[0020] When the temperature of the drive system exceeds a predetermined threshold, the upper limit of the heating power is derated based on a derating factor to obtain a first heating power;

[0021] Based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit and the first heating power, the actual heating power for heating the battery system in the current state of the electric vehicle is determined.

[0022] In some embodiments, determining the actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit includes:

[0023] Gradient-limit the heating power required to heat the battery system of the electric vehicle in the current state according to a predetermined step length to obtain a heating power gradient within a predetermined heating period;

[0024] Based on the heating power gradient within the predetermined heating period, the heating power lower limit and the heating power upper limit, an actual heating power for heating the battery system in the current state of the electric vehicle is determined.

[0025] In some embodiments, controlling the asynchronous drive motor to operate at the target excitation current and outputting a loss corresponding to the target excitation current, so as to circulate cooling water for heating the battery system of the electric vehicle based on the loss, includes:

[0026] Real-time detection of whether the drive system has over-temperature faults;

[0027] If the drive system does not have an over-temperature fault, controlling the asynchronous drive motor to operate at the target excitation current and outputting the loss corresponding to the target excitation current;

[0028] If an over-temperature fault occurs in the drive system, the asynchronous drive motor is stopped from circulating cooling water to heat the battery system of the electric vehicle.

[0029] In some embodiments, the over-temperature fault includes at least one of the following:

[0030] Motor temperature is over-temperature, inverter temperature is over-temperature and motor controller temperature is over-temperature.

[0031] In a second aspect, the present disclosure provides an electric vehicle battery system heating device, comprising:

[0032] An instruction acquisition module is used to obtain a heating power demand instruction sent by the vehicle controller; wherein the heating power demand instruction includes the heating power required to heat the battery system in the current state of the electric vehicle;

[0033] a limit determination module, configured to determine a lower limit of the heating power based on the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle, and to determine an upper limit of the heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature in the current state of the electric vehicle;

[0034] a heating power determination module, configured to determine an actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required for heating the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit;

[0035] a target excitation current determination module, configured to determine, from a current lookup table, a target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle based on the actual heating power, the bus voltage in the current state of the electric vehicle, and the speed of the asynchronous drive motor;

[0036] The battery system heating module is used to control the asynchronous drive motor to operate at the target excitation current, output the loss corresponding to the target excitation current, and perform cooling water circulation heating on the battery system of the electric vehicle based on the loss.

[0037] In a third aspect, the present disclosure provides a computer-readable storage medium storing an electric vehicle battery system heating program. When the electric vehicle battery system heating program is executed by a processor, the electric vehicle battery system heating method described in the first aspect is implemented.

[0038] In a fourth aspect, the present disclosure provides an electric vehicle, comprising a drive system; the drive system is used to execute the electric vehicle battery system heating method described in the first aspect above.

[0039] The electric vehicle battery system heating method provided by the embodiment of the present disclosure includes: obtaining a heating power demand instruction sent by a vehicle controller; wherein the heating power demand instruction includes the heating power required to heat the battery system in the current state of the electric vehicle; determining a lower limit of the heating power based on the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle, and determining an upper limit of the heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature in the current state of the electric vehicle; determining the actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required to heat the battery system in the current state of the electric vehicle, the lower limit of the heating power and the upper limit of the heating power; determining a target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle based on the actual heating power, the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle in a current lookup table; controlling the asynchronous drive motor to operate with the target excitation current, outputting the loss corresponding to the target excitation current, and performing cooling water circulation heating on the battery system of the electric vehicle based on the loss. In this application, the heating power upper limit and the heating power lower limit are used to limit the heating power required to heat the battery system in the current state of the electric vehicle contained in the heating power demand instruction, so as to determine the heating power suitable for heating the battery system in the current state of the electric vehicle, thereby reducing the damage to the drive system caused by excessive heating power and the occurrence of unsatisfactory heating of the battery system due to insufficient heating power.

[0040] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a flow chart of a method for heating a battery system of an electric vehicle according to an exemplary embodiment;

[0042] Figure 2 is a schematic diagram of an indirect heating process according to an exemplary embodiment;

[0043] Figure 3 is a schematic diagram showing the interactive state of indirect heating according to an exemplary embodiment;

[0044] Figure 4 The figure is a schematic structural diagram of a heating device for a battery system of an electric vehicle according to an exemplary embodiment. DETAILED DESCRIPTION

[0045] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present disclosure, and should not be construed as limiting the present disclosure.

[0046] Electric vehicles are becoming increasingly popular in today's society and have become the future development direction of the automotive industry. Electric vehicles are powered by power batteries. Low temperatures significantly affect the battery's charging and discharging processes, significantly reducing the vehicle's driving range. Therefore, in low-temperature environments, power battery heating is necessary to improve the battery's charging and discharging performance and increase driving range.

[0047] In view of the above situation, the present disclosure provides a method for heating a battery system of an electric vehicle. Figure 1 FIG. 1 is a flow chart showing a method for heating a battery system of an electric vehicle according to an exemplary embodiment. Figure 1 As shown, the electric vehicle battery system heating method includes:

[0048] Obtaining a heating power demand instruction sent by a vehicle controller; wherein the heating power demand instruction includes the heating power required to heat the battery system in the current state of the electric vehicle;

[0049] Determining a lower limit of heating power based on the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle, and determining an upper limit of heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature in the current state of the electric vehicle;

[0050] determining an actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required for heating the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit;

[0051] Based on the actual heating power, the bus voltage of the electric vehicle in the current state, and the speed of the asynchronous drive motor, determining in a current lookup table a target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle;

[0052] The asynchronous drive motor is controlled to operate at the target excitation current, and a loss corresponding to the target excitation current is output, so as to perform cooling water circulation heating on the battery system of the electric vehicle based on the loss.

[0053] In this exemplary embodiment, a heating power demand command for the electric vehicle can be sent by the vehicle controller to the drive system and received by the drive system's motor controller. The heating power demand command, as specified in the heating power demand command, which specifies the heating power required to heat the battery system in the current state of the electric vehicle, can be determined by the vehicle's thermal management system based on the desired temperature of the drive system.

[0054] In this exemplary embodiment, the bus voltage in the current state of the electric vehicle is a key parameter in the electric vehicle drive system, and refers to the main power supply voltage output by a DC power source (such as a battery or a capacitor).

[0055] In this exemplary embodiment, before determining the actual heating power required to heat the battery system in the current state of the electric vehicle, a lower limit for the heating power may be determined based on the current bus voltage and asynchronous drive motor speed of the electric vehicle, and an upper limit for the heating power may be determined based on the current bus voltage, asynchronous drive motor speed, and coolant temperature. When determining the lower limit for the heating power based on the current bus voltage and asynchronous drive motor speed of the electric vehicle, a lookup table for the lower limit for the heating power (see Table 1) may be pre-established based on the bus voltage, asynchronous drive motor speed, and the heating power required for heating the battery system. The lower limit for the heating power lookup table contains a correspondence between speeds at bus voltage and lower limits for the heating power. When determining the upper limit for the heating power based on the current bus voltage, asynchronous drive motor speed, and coolant temperature of the electric vehicle, a lookup table for the upper limit for the heating power (see Table 2) may be pre-established based on the current bus voltage, asynchronous drive motor speed, and coolant temperature of the electric vehicle, and the heating power required for heating the battery system. The upper limit for the heating power lookup table contains a correspondence between speeds corresponding to different coolant temperatures at bus voltage and upper limits for the heating power.

[0056] Table 1 Heating power lower limit lookup table

[0057]

[0058] Table 2 Heating power upper limit lookup table

[0059]

[0060] Table 3 Current Lookup Table

[0061]

[0062]

[0063] Table 4 Current Lookup Table

[0064]

[0065] In some embodiments, before determining in the current lookup table the target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle, the method includes:

[0066] Determine N voltage points according to the battery operating range; the N voltage points cover the maximum voltage and the minimum voltage of the battery;

[0067] The relationship among the heating power output by the drive system under the bus voltage, the rotational speed of the asynchronous drive motor and the excitation current output by the asynchronous drive motor is calibrated based on the N voltage points to obtain the current lookup table.

[0068] In this exemplary embodiment, the losses of the drive system itself can be determined through bench calibration. This application only considers drive system heating of an asynchronous motor at 0 Nm. Therefore, the losses at different currents at 0 Nm across the entire speed range must be calibrated on a bench. The control target is the asynchronous motor. Therefore, at 0 Nm, the slip is zero, meaning the current frequency is synchronized with the rotor frequency. At this point, the motor only needs to be loaded with the excitation current. However, the losses vary under different bus voltages, particularly those in the motor controller. Therefore, the impact of different bus voltages on the losses must be considered. Based on the battery operating range, three to five voltage points are determined, covering both the highest and lowest voltages, for calibration. This allows for the creation of a current lookup table corresponding to each voltage point, as shown in Tables 3 and 4. Processing this calibrated data yields the corresponding excitation current values for different speeds and system losses. In practical applications, a three-dimensional lookup table is performed based on the heating power request, combining bus voltage and speed to determine the excitation current value. The vehicle's heating power request can be divided into different gears, for example, a table for excitation current at each voltage point, with values for 1 kW, 2 kW, 3 kW, and 4 kW. In this application, the actual drive system does not have a 0kW operating condition under normal operation. When making a table, a virtual 0kW excitation current value can be used for table lookup through linear differential. In addition, the drive system will generate losses during normal operation and rotation. That is, even when no heating power is requested, the drive system itself will generate heating power. Therefore, the request for heating power has a lower limit value. If it is lower than this lower limit, it is invalid. The lower limit of loss is different under different bus voltages. Therefore, it needs to be calibrated for different bus voltages as the lower limit of loss request.

[0069] After calibration, the table lookup data required for the entire indirect heating can be obtained. After the drive system receives the indirect heating power request sent by the vehicle controller, the heating power demand instruction is slope-limited for the smoothness of the heating process. The power request instruction after the slope limitation is also subject to the upper and lower limits of the heating power. At the same time, temperature protection is taken into account. When overtemperature occurs, the upper limit of the heating power will be affected by the derating factor to reduce the heating power request to prevent the heating from causing overheating and damage to the drive system. The limited power request instruction obtains the magnitude of the excitation current through the current table lookup as the current instruction for the current closed-loop control. The loss of the drive system will heat the coolant, and after circulation, heat the battery system.

[0070] In some embodiments, determining the actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit includes:

[0071] If the heating power required for heating the battery system in the current state of the electric vehicle is between the lower limit of the heating power and the upper limit of the heating power, then determining that the heating power required for heating the battery system in the current state of the electric vehicle is the actual heating power for heating the battery system in the current state of the electric vehicle;

[0072] If the heating power required to heat the battery system in the current state of the electric vehicle is less than the heating power lower limit, determining the heating power lower limit as the actual heating power required to heat the battery system in the current state of the electric vehicle;

[0073] If the heating power required to heat the battery system in the current state of the electric vehicle is greater than the heating power upper limit, the heating power upper limit is determined to be the actual heating power required to heat the battery system in the current state of the electric vehicle.

[0074] In this exemplary embodiment, when the heating power is lower than the lower limit of the heating power, it means that the heating power may not be able to meet the driving system's heating requirements for the battery system, and the heating effect of the battery system cannot be achieved. Therefore, when the heating power required to heat the battery system in the current state of the electric vehicle is less than the lower limit of the heating power, the lower limit of the heating power is determined to be the actual heating power for heating the battery system in the current state of the electric vehicle.

[0075] When the heating power is higher than the upper limit of the heating power, it means that the heating power may be too high and may cause damage to the drive system. Therefore, when the heating power required to heat the battery system in the current state of the electric vehicle is greater than the upper limit of the heating power, the upper limit of the heating power is determined to be the actual heating power for heating the battery system in the current state of the electric vehicle.

[0076] In this exemplary embodiment, after obtaining the heating power required to heat the battery system in the current state of the electric vehicle, the range of the heating power required to heat the battery system in the current state of the electric vehicle is determined through the lower limit and upper limit of the heating power, and the actual heating power for heating the battery system in the current state of the electric vehicle is determined, which is conducive to reducing damage to the drive system caused by excessive heating power and the occurrence of unsatisfactory heating of the battery system due to insufficient heating power.

[0077] In some embodiments, determining the actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit includes:

[0078] When the temperature of the drive system exceeds a predetermined threshold, the upper limit of the heating power is derated based on a derating factor to obtain a first heating power;

[0079] Based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit and the first heating power, the actual heating power for heating the battery system in the current state of the electric vehicle is determined.

[0080] In this exemplary embodiment, the indirect heating function is allowed to be turned on when the asynchronous motor outputs 0Nm, and the excitation current required for the heating power is obtained through calibration, taking into account two factors: speed and voltage; the indirect heating power request is based on the power consumed at different speeds and different voltages in the open-tube state of the drive system as the lower limit; the upper limit of the indirect heating power, in addition to considering different voltages and different speeds, also needs to consider the coolant temperature, and the maximum heating power that can be achieved to achieve temperature balance within the allowable temperature range is used as the upper limit; temperature protection is also considered. When the temperature is too high and triggers a derating, the upper limit of the heating power will also be derated at the same time to prevent the motor from being damaged by overheating.

[0081] Figure 2 FIG. 1 is a schematic diagram of an indirect heating process according to an exemplary embodiment. Figure 2 Shown, including:

[0082] Step 20: After the indirect heating is enabled, the received heating power demand first undergoes a slope limit;

[0083] Step 21: Obtain the lower limit of heating power by looking up the table of speed and voltage;

[0084] Step 22: Obtain the upper limit of heating power by looking up the table based on the speed, bus voltage, and coolant temperature;

[0085] Step 23: Considering temperature protection, adjust the upper limit of heating power by using the derating factor;

[0086] Step 24: The power demand after limitation is input into the current lookup module;

[0087] Step 25: Use the current lookup module to add the voltage and speed signal to the table to obtain the excitation current instruction, input it into the current loop to perform current closed loop, and realize the indirect heating function.

[0088] In some embodiments, determining the actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit includes:

[0089] Gradient-limit the heating power required to heat the battery system of the electric vehicle in the current state according to a predetermined step length to obtain a heating power gradient within a predetermined heating period;

[0090] Based on the heating power gradient within the predetermined heating period, the heating power lower limit and the heating power upper limit, an actual heating power for heating the battery system in the current state of the electric vehicle is determined.

[0091] In this exemplary embodiment, the slope limit is a gradient limit of a predetermined step length. The slope limit is to make the heating smoother. Assuming the step length is 100W / 100ms, the vehicle controller suddenly gives a heating power of 1kW, then the first 100ms cycle must be executed according to 100W, and the next operation cycle of 100ms is executed according to 200W. It is equivalent to judging the deviation between the actual execution of the heating power and the new heating power. If it exceeds the step length of 100W, then only 100W will be increased for execution. The reduction of the heating power can also follow this step length. In this way, the heating power required to heat the battery system in the current state of the electric vehicle can be gradient-limited according to the predetermined step length and executed in batches.

[0092] In some embodiments, controlling the asynchronous drive motor to operate at the target excitation current and outputting a loss corresponding to the target excitation current, so as to circulate cooling water for heating the battery system of the electric vehicle based on the loss, includes:

[0093] Real-time detection of whether the drive system has over-temperature faults;

[0094] If the drive system does not have an over-temperature fault, controlling the asynchronous drive motor to operate at the target excitation current and outputting the loss corresponding to the target excitation current;

[0095] If an over-temperature fault occurs in the drive system, the asynchronous drive motor is stopped from circulating cooling water to heat the battery system of the electric vehicle.

[0096] In this exemplary embodiment, during the battery system heating process, the drive system can be detected in real time to determine whether it has an overtemperature fault. If the motor temperature is overtemperature, the inverter temperature is overtemperature, or the motor controller temperature is overtemperature, heating of the battery system can be stopped.

[0097] In this exemplary embodiment, the drive system and the vehicle controller need to exchange information on the heating status. When the drive system is fault-free and the temperature of the motor and controller is below a certain threshold, feedback is given to the vehicle controller to allow heating. If the vehicle sends a signal to enable the heating function, the drive system enters the heating mode. When the vehicle controller sends a signal to stop indirect heating, the heating status is allowed and the heating function is initialized. If a fault occurs during the heating process or the temperature is too high, including the motor temperature and the controller temperature, feedback is given to the vehicle to disallow heating. In this case, the vehicle exits the heating mode due to its own reasons. When the fault is restored and the temperature drops, the corresponding control mode is entered according to the heating enable flag.

[0098] Figure 3 FIG. 1 is a schematic diagram showing the interaction of the intermediate indirect heating state according to an exemplary embodiment. Figure 3 As shown, first, the default state feedback is to allow heating, and step 31 is executed to enter the heating mode;

[0099] When a fault occurs or the controller temperature is too high or the motor temperature is too high, step 32 is executed to exit the heating mode;

[0100] When the fault condition is eliminated, and the controller temperature and the motor temperature are normal but indirect heating is prohibited, step 33 is executed to request to resume the heating mode, and then step 35 is executed to enable the heating mode by indirect heating;

[0101] If a fault state occurs in the initial state or the controller temperature is too high or the motor temperature is too high, step 34 is executed to exit the heating mode.

[0102] The above-mentioned indirect heating method and strategy for the drive system do not require any changes to the hardware system. It can be implemented by only changing the motor control software, which is simple and low-cost. Indirect heating is performed when the drive system is at 0Nm. This method can be used for heating when the vehicle is parked or driving, without any impact on actual driving needs. The indirect heating function can be turned on within the full speed range of the drive system. The influence of voltage and speed on the heating power is taken into account, thereby improving the accuracy of the heating power. The influence of coolant temperature is taken into account, and the maximum heating power is limited to prevent the drive system temperature from being too high. Temperature derating will also reduce the maximum allowable heating power, thereby improving the safety of the system. The status of the indirect heating is fed back in real time by interacting with the entire vehicle system.

[0103] In this application, the asynchronous motor drive system heats the coolant by loading the excitation current, thereby heating the battery system, and at the same time interacts with the vehicle controller to monitor the heating status. If the temperature is too high or other faults occur, the vehicle will be fed back to indicate that heating is not allowed. The asynchronous motor allows the indirect heating function to be turned on when the output is 0Nm. The excitation current required for the heating power is obtained through calibration, taking into account two factors: speed and voltage. The indirect heating power request is based on the power consumed by the drive system at different speeds and voltages in the open-tube state as the lower limit. In addition to considering different voltages and speeds, the upper limit of the indirect heating power also needs to consider the coolant temperature. The maximum heating power that can be achieved to achieve temperature equilibrium within the allowable temperature range is the upper limit. At the same time, temperature protection is taken into account. When the temperature is too high and the derating is triggered, the upper limit of the heating power will also be reduced to prevent the motor from being damaged by overheating.

[0104] The present disclosure provides a heating device for an electric vehicle battery system. Figure 4 FIG. 1 is a schematic diagram showing the structure of a heating device for an electric vehicle battery system according to an exemplary embodiment. Figure 4 As shown, the electric vehicle battery system heating device includes:

[0105] The instruction acquisition module 40 is used to obtain the heating power demand instruction sent by the vehicle controller; wherein the heating power demand instruction includes the heating power required to heat the battery system in the current state of the electric vehicle;

[0106] a limit value determination module 41 for determining a lower limit of the heating power based on the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle, and determining an upper limit of the heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature in the current state of the electric vehicle;

[0107] a heating power determination module 42, configured to determine an actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required for heating the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit;

[0108] a target excitation current determination module 43, configured to determine, from a current lookup table, a target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle, based on the actual heating power, the bus voltage in the current state of the electric vehicle, and the speed of the asynchronous drive motor;

[0109] The battery system heating module is used to control the asynchronous drive motor to operate at the target excitation current, output the loss corresponding to the target excitation current, and perform cooling water circulation heating on the battery system of the electric vehicle based on the loss.

[0110] In this exemplary embodiment, a heating power demand command for the electric vehicle can be sent by the vehicle controller to the drive system and received by the drive system's motor controller. The heating power demand command, as specified in the heating power demand command, which specifies the heating power required to heat the battery system in the current state of the electric vehicle, can be determined by the vehicle's thermal management system based on the desired temperature of the drive system.

[0111] In this exemplary embodiment, the bus voltage in the current state of the electric vehicle is a key parameter in the electric vehicle drive system, and refers to the main power supply voltage output by a DC power source (such as a battery or a capacitor).

[0112] In this exemplary embodiment, before determining the actual heating power required to heat the battery system in the current state of the electric vehicle, a lower limit for the heating power may be determined based on the current bus voltage and asynchronous drive motor speed of the electric vehicle, and an upper limit for the heating power may be determined based on the current bus voltage, asynchronous drive motor speed, and coolant temperature. When determining the lower limit for the heating power based on the current bus voltage and asynchronous drive motor speed of the electric vehicle, a lookup table for the lower limit for the heating power (see Table 1) may be pre-established based on the bus voltage, asynchronous drive motor speed, and the heating power required for heating the battery system. The lower limit for the heating power lookup table contains a correspondence between speeds at bus voltage and lower limits for the heating power. When determining the upper limit for the heating power based on the current bus voltage, asynchronous drive motor speed, and coolant temperature of the electric vehicle, a lookup table for the upper limit for the heating power (see Table 2) may be pre-established based on the current bus voltage, asynchronous drive motor speed, and coolant temperature of the electric vehicle, and the heating power required for heating the battery system. The upper limit for the heating power lookup table contains a correspondence between speeds corresponding to different coolant temperatures at bus voltage and upper limits for the heating power.

[0113] The electric vehicle battery system heating device of the present application can refer to the above electric vehicle battery system heating method.

[0114] The present disclosure provides a computer-readable storage medium on which an electric vehicle battery system heating program is stored. When the electric vehicle battery system heating program is executed by a processor, the electric vehicle battery system heating method described in the above embodiment is implemented.

[0115] The present disclosure provides an electric vehicle, comprising a drive system; the drive system is used to execute the electric vehicle battery system heating method described in the above embodiment.

[0116] It should be noted that the logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can retrieve and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transmit a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion having one or more wires (electronic device), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or otherwise processing it in a suitable manner if necessary, and then storing it in a computer memory.

[0117] It should be understood that various parts of the present disclosure can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0118] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0119] In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present disclosure.

[0120] In addition, the terms "first" and "second" used in the embodiments of the present disclosure are only used for descriptive purposes and should not be understood as indicating or implying relative importance, or implicitly indicating the number of technical features indicated in the embodiments. Therefore, the features defined in the embodiments of the present disclosure with terms such as "first" and "second" can explicitly or implicitly indicate that the embodiment includes at least one such feature. In the description of the present disclosure, the word "plurality" means at least two or two or more, such as two, three, four, etc., unless otherwise clearly and specifically defined in the embodiments.

[0121] In this disclosure, unless otherwise clearly specified or limited in the embodiments, the terms "installed," "connected," "connect," and "fixed" appearing in the embodiments should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection. It can also be a mechanical connection, an electrical connection, etc.; of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication between two elements, or the interaction between two elements. For those skilled in the art, the specific meanings of the above terms in this disclosure can be understood based on the specific implementation.

[0122] In the present disclosure, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0123] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. A method for heating an electric vehicle battery system, characterized in that: include: Obtaining a heating power demand instruction sent by a vehicle controller; wherein the heating power demand instruction includes the heating power required to heat the battery system in the current state of the electric vehicle; Determining a lower limit of heating power based on the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle, and determining an upper limit of heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature in the current state of the electric vehicle; determining an actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required for heating the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit; Based on the actual heating power, the bus voltage of the electric vehicle in the current state, and the speed of the asynchronous drive motor, determining in a current lookup table a target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle; The asynchronous drive motor is controlled to operate at the target excitation current, and a loss corresponding to the target excitation current is output, so as to perform cooling water circulation heating on the battery system of the electric vehicle based on the loss.

2. The electric vehicle battery system heating method according to claim 1, characterized in that: Before determining in the current lookup table the target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle, the method includes: Determine N voltage points according to the battery operating range; the N voltage points cover the maximum voltage and the minimum voltage of the battery; The relationship among the heating power output by the drive system under the bus voltage, the rotational speed of the asynchronous drive motor and the excitation current output by the asynchronous drive motor is calibrated based on the N voltage points to obtain the current lookup table.

3. The electric vehicle battery system heating method according to claim 2, characterized in that: The determining, based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit, of the actual heating power for heating the battery system in the current state of the electric vehicle includes: If the heating power required for heating the battery system in the current state of the electric vehicle is between the lower limit of the heating power and the upper limit of the heating power, then determining that the heating power required for heating the battery system in the current state of the electric vehicle is the actual heating power for heating the battery system in the current state of the electric vehicle; If the heating power required to heat the battery system in the current state of the electric vehicle is less than the heating power lower limit, determining the heating power lower limit as the actual heating power required to heat the battery system in the current state of the electric vehicle; If the heating power required to heat the battery system in the current state of the electric vehicle is greater than the heating power upper limit, the heating power upper limit is determined to be the actual heating power required to heat the battery system in the current state of the electric vehicle.

4. The electric vehicle battery system heating method according to claim 1, characterized in that: The determining, based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit, of the actual heating power for heating the battery system in the current state of the electric vehicle includes: When the temperature of the drive system exceeds a predetermined threshold, the upper limit of the heating power is derated based on a derating factor to obtain a first heating power; Based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit and the first heating power, the actual heating power for heating the battery system in the current state of the electric vehicle is determined.

5. The electric vehicle battery system heating method according to claim 1, characterized in that: The determining, based on the heating power required to heat the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit, of the actual heating power for heating the battery system in the current state of the electric vehicle includes: Gradient-limit the heating power required to heat the battery system of the electric vehicle in the current state according to a predetermined step length to obtain a heating power gradient within a predetermined heating period; Based on the heating power gradient within the predetermined heating period, the heating power lower limit and the heating power upper limit, an actual heating power for heating the battery system in the current state of the electric vehicle is determined.

6. The electric vehicle battery system heating method according to claim 1, characterized in that: The step of controlling the asynchronous drive motor to operate at the target excitation current and outputting a loss corresponding to the target excitation current, so as to circulate cooling water for heating the battery system of the electric vehicle based on the loss, includes: Real-time detection of whether the drive system has over-temperature faults; If the drive system does not have an over-temperature fault, controlling the asynchronous drive motor to operate at the target excitation current and outputting the loss corresponding to the target excitation current; If an over-temperature fault occurs in the drive system, the asynchronous drive motor is stopped from circulating cooling water to heat the battery system of the electric vehicle.

7. The electric vehicle battery system heating method according to claim 6, characterized in that: The over-temperature fault includes at least one of the following: Motor temperature is over-temperature, inverter temperature is over-temperature and motor controller temperature is over-temperature.

8. A heating device for an electric vehicle battery system, characterized in that: include: An instruction acquisition module is used to obtain a heating power demand instruction sent by the vehicle controller; wherein the heating power demand instruction includes the heating power required to heat the battery system in the current state of the electric vehicle; a limit determination module, configured to determine a lower limit of the heating power based on the bus voltage and the speed of the asynchronous drive motor in the current state of the electric vehicle, and to determine an upper limit of the heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature in the current state of the electric vehicle; a heating power determination module, configured to determine an actual heating power for heating the battery system in the current state of the electric vehicle based on the heating power required for heating the battery system in the current state of the electric vehicle, the heating power lower limit, and the heating power upper limit; a target excitation current determination module, configured to determine, from a current lookup table, a target excitation current that the asynchronous drive motor needs to output when heating the battery system in the current state of the electric vehicle based on the actual heating power, the bus voltage in the current state of the electric vehicle, and the speed of the asynchronous drive motor; The battery system heating module is used to control the asynchronous drive motor to operate at the target excitation current, output the loss corresponding to the target excitation current, and perform cooling water circulation heating on the battery system of the electric vehicle based on the loss.

9. A computer-readable storage medium, characterized in that An electric vehicle battery system heating program is stored thereon, and when the electric vehicle battery system heating program is executed by the processor, the electric vehicle battery system heating method according to any one of claims 1 to 7 is implemented.

10. An electric vehicle, characterized in that: It comprises a drive system; the drive system is used to execute the electric vehicle battery system heating method according to any one of claims 1 to 7.

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