Electric vehicle battery system heating method and heating device

Abstract

The present disclosure relates to an electric vehicle battery system heating method and a heating device. The electric vehicle battery system heating method belongs to the technical field of electric vehicles and comprises the following steps: obtaining a heating power demand instruction sent by a vehicle controller; determining an actual heating power for heating the battery system in the current state of the electric vehicle based on a heating power required for heating the battery system in the current state of the electric vehicle, a lower limit of the heating power and an upper limit of the heating power; determining a target excitation current required for an asynchronous driving motor to output when heating the battery system in the current state of the electric vehicle based on the actual heating power, a bus voltage in the current state of the electric vehicle and a rotational speed of the asynchronous driving motor in a current lookup table; controlling the asynchronous driving motor to work at the target excitation current and output a 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.

Description

TECHNICAL FIELD

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

[0002] Electric vehicles are increasingly popular in current society and have become the future direction of the current automotive industry. The power source of electric vehicles is power batteries, and low temperature has a great influence on the charging and discharging process of the batteries, which seriously shortens the driving range of electric vehicles. Therefore, in a low temperature environment, the power battery needs to be heated to improve the charging and discharging performance of the battery and improve the driving range. SUMMARY

[0003] Therefore, the embodiments of the present disclosure expect 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 implemented as follows:

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

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

[0007] obtaining a heating power demand instruction sent by a vehicle controller, wherein the heating power demand instruction comprises a heating power required for heating the battery system under the current state of the electric vehicle;

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

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

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

[0011] controlling the asynchronous drive motor to work at the target excitation current, outputting a 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.

[0012] In some embodiments, before determining 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 by looking up a current table, the method includes:

[0013] Based on the battery's operating range, N voltage points are determined; these N voltage points cover the battery's highest and lowest voltages.

[0014] Based on the N voltage points, the relationship between the heating power output by the drive system under the bus voltage, the speed of the asynchronous drive motor, and the excitation current output by the asynchronous drive motor is calibrated, and the current lookup table is obtained.

[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 lower limit of the heating power, and the upper limit of the heating power, includes:

[0016] If the heating power required to heat 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 the heating power required to heat the battery system in the current state of the electric vehicle is determined to be the actual heating power required to heat 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 lower limit of the heating power, then the lower limit of the heating power is determined to be 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 upper limit of the heating power, then the upper limit of the heating power 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 lower limit of the heating power, and the upper limit of the heating power, includes:

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

[0021] 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 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 lower limit of the heating power, and the upper limit of the heating power, includes:

[0023] The heating power required to heat the battery system in the current state of the electric vehicle is gradient-limited according to a predetermined step size to obtain the heating power gradient within a predetermined heating period.

[0024] Based on the heating power gradient during the predetermined heating period, the lower limit of the heating power, and the upper limit of the heating power, the 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 with the target excitation current and outputting the loss corresponding to the target excitation current to perform cooling water circulation heating on the battery system of the electric vehicle based on the loss includes:

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

[0027] If the drive system does not have an over-temperature fault, the asynchronous drive motor is controlled to operate with the target excitation current, and the loss corresponding to the target excitation current is output.

[0028] If the drive system has an overheating fault, the asynchronous drive motor will stop 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 overheating, inverter overheating, and motor controller overheating.

[0031] Secondly, this disclosure provides a heating device for an electric vehicle battery system, comprising:

[0032] The instruction acquisition module is used to acquire 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;

[0033] The limit determination module is used to determine the lower limit of heating power based on the bus voltage and the speed of the asynchronous drive motor under the current state of the electric vehicle, and to determine the upper limit of heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature under the current state of the electric vehicle.

[0034] The heating power determination module is used to determine the actual heating power of 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.

[0035] The target excitation current determination module is used to determine 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, 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, by looking up a current table.

[0036] The battery system heating module is used to control the asynchronous drive motor to operate with 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] Thirdly, this disclosure provides a computer-readable storage medium storing an electric vehicle battery system heating program thereon, which, when executed by a processor, implements the electric vehicle battery system heating method described in the first aspect above.

[0038] Fourthly, this disclosure provides an electric vehicle, including a drive system; the drive system is used to perform the electric vehicle battery system heating method described in the first aspect above.

[0039] The electric vehicle battery system heating method provided in this disclosure includes: acquiring a heating power demand command sent by the vehicle controller; wherein the heating power demand command 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 the actual heating power required to heat 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 heating power, and the upper limit of heating power; determining 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 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, and using a current lookup table; controlling the asynchronous drive motor to operate at the target excitation current, outputting the loss corresponding to the target excitation current, and using the loss to perform cooling water circulation heating of the battery system of the electric vehicle. In this application, the heating power required to heat the battery system in the current state of the electric vehicle is limited by the upper limit and lower limit of the heating power. This determines the appropriate heating power 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 unsatisfactory heating of the battery system caused by insufficient heating power.

[0040] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

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

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

[0043] Figure 3 This is a schematic diagram illustrating the interaction of intermediate indirect heating states according to an exemplary embodiment;

[0044] Figure 4 This is a schematic diagram of the structure of a heating device for an electric vehicle battery system according to an exemplary embodiment. Detailed Implementation

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

[0046] Electric vehicles are becoming increasingly popular in society and have become the future direction of the automotive industry. The power source of electric vehicles is the battery, and low temperatures significantly affect the charging and discharging process of the battery, severely shortening the driving range of electric vehicles. Therefore, in low-temperature environments, it is necessary to heat the battery to improve its charging and discharging performance and increase the driving range.

[0047] In view of the above situation, this disclosure provides a heating method for an electric vehicle battery system. Figure 1 This is a schematic diagram illustrating a heating method for an electric vehicle battery system according to an exemplary embodiment. Figure 1 As shown, the electric vehicle battery system heating method includes:

[0048] 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;

[0049] The lower limit of heating power is determined based on the bus voltage and the speed of the asynchronous drive motor under the current state of the electric vehicle, and the upper limit of heating power is determined based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature under the current state of the electric vehicle.

[0050] 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, the actual heating power for heating the battery system in the current state of the electric vehicle is determined.

[0051] Based on the actual heating power, the bus voltage of the electric vehicle in its current state, and the speed of the asynchronous drive motor, 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 is determined by looking up the current table.

[0052] The asynchronous drive motor is controlled to operate with the target excitation current, and the loss corresponding to the target excitation current is output to circulate and heat the battery system of the electric vehicle based on the loss.

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

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

[0055] In this exemplary embodiment, before determining the actual heating power for heating the battery system under the current state of the electric vehicle, a lower limit of heating power can be determined based on the bus voltage and the rotational speed of the asynchronous drive motor under the current state of the electric vehicle, and an upper limit of heating power can be determined based on the bus voltage, the rotational speed of the asynchronous drive motor, and the coolant temperature under the current state of the electric vehicle. When determining the lower limit of heating power based on the bus voltage and the rotational speed of the asynchronous drive motor under the current state of the electric vehicle, a lower limit lookup table as shown in Table 1 can be established in advance based on the bus voltage, the rotational speed of the asynchronous drive motor, and the heating power required for heating the battery system by the electric vehicle. The lower limit lookup table contains the correspondence between the rotational speed and the lower limit of heating power under the bus voltage. When determining the upper limit of heating power based on the bus voltage, the rotational speed of the asynchronous drive motor, and the coolant temperature under the current state of the electric vehicle, a higher limit lookup table as shown in Table 2 can be established in advance based on the upper limit of heating power determined based on the bus voltage, the rotational speed of the asynchronous drive motor, and the coolant temperature under the current state of the electric vehicle, and the heating power required for heating the battery system by the electric vehicle. The upper limit lookup table contains the correspondence between the rotational speed corresponding to different coolant temperatures under the bus voltage and the upper limit of heating power.

[0056] Table 1: Lower Limit of Heating Power (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 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 by looking up a current table, the method includes:

[0066] Based on the battery's operating range, N voltage points are determined; these N voltage points cover the battery's highest and lowest voltages.

[0067] Based on the N voltage points, the relationship between the heating power output by the drive system under the bus voltage, the speed of the asynchronous drive motor, and the excitation current output by the asynchronous drive motor is calibrated, and the current lookup table is obtained.

[0068] In this exemplary embodiment, the losses of the drive system itself can be obtained through bench calibration. This application only considers the heating of the drive system of the asynchronous motor at 0 Nm, so it is necessary to calibrate the losses of different currents at 0 Nm across the entire speed range on a bench, and the controlled object is the asynchronous motor. Therefore, at 0 Nm, the slip is 0, that is, the current frequency is synchronized with the rotor frequency. At this time, the motor only needs to be loaded with excitation current, but the losses are different under different bus voltages, especially the losses of the motor controller. Therefore, it is necessary to consider the influence of different bus voltages on the magnitude of the losses. Based on the battery operating range, 3 to 5 voltage points are determined, covering the highest and lowest voltages for calibration. In this way, current lookup tables corresponding to each voltage point can be established as shown in Tables 3 and 4. After processing the data calibrated above, the magnitude of the excitation current corresponding to different speeds and system losses can be obtained. In practical applications, it is necessary to perform a three-dimensional lookup table based on the heating power request, combined with the bus voltage and speed, to obtain the magnitude of the excitation current. The heating power request of the whole vehicle can be requested in different levels, such as 1kW / 2kW / 3kW / 4kW, and the excitation current table for one voltage point. In practice, the drive system does not operate at 0kW under normal conditions. When creating tables, a virtual 0kW excitation current value can be generated using linear differential methods for table lookup. Furthermore, the drive system generates losses during normal operation and rotation. Even without a requested heating power, the drive system itself generates heating power. Therefore, there is a lower limit to the heating power request; values ​​below this limit are invalid. The lower limit for losses differs for different bus voltages, thus requiring calibration for different bus voltages to establish the lower limit for the loss request.

[0069] Once calibration is complete, the lookup table data required for the entire indirect heating process is obtained. After the drive system receives the indirect heating power request from the vehicle controller, the heating power demand command is slope-limited to ensure a smooth heating process. The power request command after slope limitation is then further limited by upper and lower heating power limits. Simultaneously, temperature protection is considered; in case of overheating, the upper limit of the heating power is reduced by a derating factor to prevent overheating and damage to the drive system. The limited power request command uses a current lookup table to obtain the excitation current, which serves as the current command for current closed-loop control. Drive system losses heat the coolant, which, after circulation, heats 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 lower limit of the heating power, and the upper limit of the heating power, includes:

[0071] If the heating power required to heat 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 the heating power required to heat the battery system in the current state of the electric vehicle is determined to be the actual heating power required to heat 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 lower limit of the heating power, then the lower limit of the heating power is determined to be 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 upper limit of the heating power, then the upper limit of the heating power 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 heating power, it indicates that the heating power may not be able to meet the heating requirements of the drive system for the battery system and cannot achieve the heating effect of the battery system. 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 heating power, the lower limit of 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 indicates that the heating power may be too high and may damage 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 required to heat 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 by the lower limit and the upper limit of the heating power. This determines the actual heating power required to heat the battery system in the current state of the electric vehicle, which helps to reduce the damage to the drive system caused by excessive heating power and the occurrence of unsatisfactory heating of the battery system caused by 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 lower limit of the heating power, and the upper limit of the heating power, includes:

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

[0079] 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 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 of the asynchronous motor is enabled when the output is 0 Nm. The excitation current required for the heating power is obtained through calibration, taking into account both speed and voltage. The indirect heating power request is limited to the power consumed at different speeds and voltages under the open state of the drive system. The upper limit of the indirect heating power, in addition to considering different voltages and speeds, also needs to consider the coolant temperature. The maximum heating power that can be achieved to reach temperature equilibrium within the allowable temperature range is taken as the upper limit. At the same time, temperature protection is considered. When the temperature is too high and derating is triggered, the upper limit of the heating power will also be drated to prevent the motor from being damaged by overheating.

[0081] Figure 2 This is a schematic diagram illustrating an intermediate indirect heating process according to an exemplary embodiment. For example... Figure 2 As shown, it includes:

[0082] Step 20: After indirect heating is enabled, the received heating power must first pass through a slope limit.

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

[0084] Step 22: Obtain the upper limit of heating power by referring to the table using rotational speed, bus voltage, and coolant temperature;

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

[0086] Step 24: Input the power demand after limitation into the current lookup table module;

[0087] Step 25: Using the current lookup module, the excitation current command is obtained by looking up the voltage and speed signals, and then input into the current loop to achieve 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 lower limit of the heating power, and the upper limit of the heating power, includes:

[0089] The heating power required to heat the battery system in the current state of the electric vehicle is gradient-limited according to a predetermined step size to obtain the heating power gradient within a predetermined heating period.

[0090] Based on the heating power gradient during the predetermined heating period, the lower limit of the heating power, and the upper limit of the heating power, the 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 limitation is a gradient limitation with a predetermined step size. The slope limitation is designed to make the heating process smoother. Assuming a step size of 100W / 100ms, if the vehicle controller suddenly provides a heating power of 1kW, the first 100ms cycle will execute at 100W, and the next 100ms cycle will execute at 200W. This is equivalent to determining if the deviation between the actual heating power and the new heating power exceeds the step size of 100W; if so, only an increase of 100W is made. A decrease in heating power can also follow this step size. 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 a predetermined step size and executed in batches.

[0092] In some embodiments, controlling the asynchronous drive motor to operate with the target excitation current and outputting the loss corresponding to the target excitation current to perform cooling water circulation heating on the battery system of the electric vehicle based on the loss includes:

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

[0094] If the drive system does not have an over-temperature fault, the asynchronous drive motor is controlled to operate with the target excitation current, and the loss corresponding to the target excitation current is output.

[0095] If the drive system has an overheating fault, the asynchronous drive motor will stop circulating cooling water to heat the battery system of the electric vehicle.

[0096] In this exemplary embodiment, the presence of over-temperature faults in the drive system can be detected in real time during the battery system heating process. If over-temperature issues are found in the motor, inverter, or motor controller, the heating of the battery system can be stopped.

[0097] In this exemplary embodiment, the drive system and the vehicle controller need to exchange information regarding the heating status. When the drive system is fault-free and the temperatures of the motor and controller are below a certain threshold, it sends feedback to the vehicle controller allowing heating. If the vehicle controller sends a heating function enable signal, the drive system enters heating mode. When the vehicle controller sends a signal to stop indirect heating, it sends feedback to the vehicle allowing heating and initializes the heating function. If a fault occurs during heating or the temperature is too high, including the motor and controller temperatures, it sends feedback to the vehicle disallowing heating, indicating that the heating mode is exiting due to its own inherent causes. Once the fault is resolved and the temperature decreases, the drive system enters the corresponding control mode based on the heating enable flag.

[0098] Figure 3 This is a schematic diagram illustrating the interaction of intermediate heating states according to an exemplary embodiment. Figure 3 As shown, the default status feedback is that heating is allowed, and step 31 is executed to enter the heating mode;

[0099] If a fault occurs, or the controller temperature or motor temperature is too high, proceed to step 32 to exit the heating mode.

[0100] When the fault condition is cleared, and the controller temperature and motor temperature are normal but indirect heating is prohibited, then step 33 is executed to request the restoration of the heating mode, and then step 35 is executed to enable the heating mode through indirect heating.

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

[0102] The aforementioned indirect heating method and strategy for the drive system requires no changes to the hardware system; only the motor control software needs modification, making it simple and low-cost. Indirect heating is performed when the drive system operates at 0 Nm, allowing it to be activated both when the vehicle is parked and in motion, without affecting actual driving needs. The indirect heating function can be activated across the entire speed range of the drive system. The influence of voltage and speed on heating power is considered, improving the accuracy of heating power output. The influence of coolant temperature is taken into account, limiting the maximum heating power to prevent the drive system from overheating. Temperature derating simultaneously reduces the maximum permissible heating power, improving system safety. Status interaction with the vehicle system provides real-time feedback on the indirect heating status.

[0103] In this application, the asynchronous motor drive system heats the coolant by applying an excitation current, thereby heating the battery system. Simultaneously, it interacts with the vehicle controller regarding the heating status. If overheating or other faults occur, it sends a signal to the vehicle to disallow heating. The asynchronous motor's indirect heating function is enabled when it outputs 0 Nm. The excitation current required for the heating power is determined through calibration, considering both speed and voltage. The indirect heating power request is limited to the power consumed by the drive system under different speeds and voltages when the drive system is in operation. The upper limit of the indirect heating power, in addition to considering different voltages and speeds, also takes into account the coolant temperature, setting the maximum heating power achievable within the permissible temperature range to reach temperature equilibrium as the upper limit. Temperature protection is also considered; when overheating triggers derating, the upper limit of the heating power is also drated simultaneously to prevent motor overheating damage.

[0104] This disclosure provides a heating device for an electric vehicle battery system. Figure 4 This is a schematic diagram illustrating 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 acquire 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] The limit determination module 41 is used to determine the lower limit of heating power based on the bus voltage and the speed of the asynchronous drive motor under the current state of the electric vehicle, and to determine the upper limit of heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature under the current state of the electric vehicle.

[0107] The heating power determination module 42 is used to determine the actual heating power of the electric vehicle's battery system under the current state of the electric vehicle, based on the heating power required to heat the battery system under the current state of the electric vehicle, the lower limit of the heating power, and the upper limit of the heating power.

[0108] The target excitation current determination module 43 is used to determine 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, 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, by looking up a current table.

[0109] The battery system heating module is used to control the asynchronous drive motor to operate with 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, the heating power demand command for the electric vehicle can be sent from the vehicle controller to the drive system and received by the motor controller of the drive system. The heating power required to heat the battery system in the current state of the electric vehicle in the heating power demand command can be determined by the vehicle's thermal management system based on the temperature required by the drive system.

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

[0112] In this exemplary embodiment, before determining the actual heating power for heating the battery system under the current state of the electric vehicle, a lower limit of heating power can be determined based on the bus voltage and the rotational speed of the asynchronous drive motor under the current state of the electric vehicle, and an upper limit of heating power can be determined based on the bus voltage, the rotational speed of the asynchronous drive motor, and the coolant temperature under the current state of the electric vehicle. When determining the lower limit of heating power based on the bus voltage and the rotational speed of the asynchronous drive motor under the current state of the electric vehicle, a lower limit lookup table as shown in Table 1 can be established in advance based on the bus voltage, the rotational speed of the asynchronous drive motor, and the heating power required for heating the battery system by the electric vehicle. The lower limit lookup table contains the correspondence between the rotational speed and the lower limit of heating power under the bus voltage. When determining the upper limit of heating power based on the bus voltage, the rotational speed of the asynchronous drive motor, and the coolant temperature under the current state of the electric vehicle, a higher limit lookup table as shown in Table 2 can be established in advance based on the upper limit of heating power determined based on the bus voltage, the rotational speed of the asynchronous drive motor, and the coolant temperature under the current state of the electric vehicle, and the heating power required for heating the battery system by the electric vehicle. The upper limit lookup table contains the correspondence between the rotational speed corresponding to different coolant temperatures under the bus voltage and the upper limit of heating power.

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

[0114] This disclosure provides a computer-readable storage medium storing an electric vehicle battery system heating program thereon, which, when executed by a processor, implements the electric vehicle battery system heating method described in the above embodiments.

[0115] This disclosure provides an electric vehicle, including a drive system; the drive system is used to perform the electric vehicle battery system heating method described in the above embodiments.

[0116] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing 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 (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0117] It should be understood that various parts of this 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 memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0118] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions 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 one or more embodiments or examples.

[0119] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

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

[0121] In this disclosure, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing," etc., appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; 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 components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific implementation.

[0122] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0123] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A heating method for an electric vehicle battery system, characterized in that, include: 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; The lower limit of heating power is determined based on the bus voltage and the speed of the asynchronous drive motor under the current state of the electric vehicle, and the upper limit of heating power is determined based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature under 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, the actual heating power for heating the battery system in the current state of the electric vehicle is determined. Based on the actual heating power, the bus voltage of the electric vehicle in its current state, and the speed of the asynchronous drive motor, 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 is determined by looking up the current table. The asynchronous drive motor is controlled to operate with the target excitation current, and the loss corresponding to the target excitation current is output to circulate and heat 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 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 by looking up the current table, the method includes: Based on the battery's operating range, N voltage points are determined; these N voltage points cover the battery's highest and lowest voltages. Based on the N voltage points, the relationship between the heating power output by the drive system under the bus voltage, the speed of the asynchronous drive motor, and the excitation current output by the asynchronous drive motor is calibrated, and the current lookup table is obtained.

3. The electric vehicle battery system heating method according to claim 2, characterized in that, The determination of 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 under the current state of the electric vehicle, the lower limit of the heating power, and the upper limit of the heating power, includes: If the heating power required to heat 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 the heating power required to heat the battery system in the current state of the electric vehicle is determined to be 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 less than the lower limit of the heating power, then the lower limit of the heating power is determined to be 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 upper limit of the heating power, then the upper limit of the heating power 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 determination of 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 under the current state of the electric vehicle, the lower limit of the heating power, and the upper limit of the heating power, includes: When the temperature of the drive system exceeds a predetermined threshold, the upper limit of the heating power is dated based on the derating factor to obtain the first heating power; 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 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 determination of 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 under the current state of the electric vehicle, the lower limit of the heating power, and the upper limit of the heating power, includes: The heating power required to heat the battery system in the current state of the electric vehicle is gradient-limited according to a predetermined step size to obtain the heating power gradient within a predetermined heating period. Based on the heating power gradient during the predetermined heating period, the lower limit of the heating power, and the upper limit of the heating power, the 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 method of controlling the asynchronous drive motor to operate with the target excitation current and outputting the loss corresponding to the target excitation current, so as to perform cooling water circulation heating on the battery system of the electric vehicle based on the loss, includes: Real-time detection of over-temperature faults in the drive system; If the drive system does not have an over-temperature fault, the asynchronous drive motor is controlled to operate with the target excitation current, and the loss corresponding to the target excitation current is output. If the drive system has an overheating fault, the asynchronous drive motor will stop 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 overheating, inverter overheating, and motor controller overheating.

8. A heating device for an electric vehicle battery system, characterized in that, include: The instruction acquisition module is used to acquire 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; The limit determination module is used to determine the lower limit of heating power based on the bus voltage and the speed of the asynchronous drive motor under the current state of the electric vehicle, and to determine the upper limit of heating power based on the bus voltage, the speed of the asynchronous drive motor and the coolant temperature under the current state of the electric vehicle. The heating power determination module is used to determine the actual heating power of 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. The target excitation current determination module is used to determine 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, 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, by looking up a current table. The battery system heating module is used to control the asynchronous drive motor to operate with 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, It stores an electric vehicle battery system heating program, which, when executed by a processor, implements the electric vehicle battery system heating method according to any one of claims 1-7.

10. An electric vehicle, characterized in that, Includes a drive system; the drive system is used to perform the electric vehicle battery system heating method according to any one of claims 1-7.

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