Heating method of power battery, electronic equipment and vehicle

Abstract

The invention discloses a heating method of a power battery, electronic equipment and a vehicle, and belongs to the technical field of new energy vehicles. Comprising the steps of determining current heating power of a driving motor based on current operation parameters of the driving motor of the vehicle and current electric quantity and required temperature of a power battery; under the condition that the current heating power does not meet the heating requirement of the power battery, a target deviation angle is determined based on the difference between the current heating power and the required heating power of the power battery, and the target deviation angle is used for increasing the loss of the driving motor; and adjusting the electrical angle of the stator current of the driving motor based on the target deviation angle, so that heat can be generated by accurately changing the loss of the motor according to the actual heating requirement, the heating efficiency of the motor can be improved, the heating requirement of the power battery can be accurately responded, and the temperature of the power battery can be rapidly increased.

Description

Technical Field

[0001] This application relates to the field of new energy vehicle technology, and in particular to a heating method for a power battery, electronic equipment, and a vehicle. Background Technology

[0002] For new energy vehicles, the primary power source is the battery. The electrochemical properties of the battery are extremely sensitive to temperature. In low-temperature environments, the viscosity of the electrolyte inside the battery increases, the lithium-ion migration rate slows significantly, and the battery's ion conductivity decreases. This leads to reduced charging and discharging efficiency, making it impossible to efficiently discharge to the drive motor, which affects the vehicle's driving performance.

[0003] In related technologies, when the battery management system detects that the battery temperature is below a certain temperature threshold, it sends a heating request to the motor controller. The motor controller then retrieves the corresponding heating power from a pre-calibrated speed-voltage-heating power relationship table based on the current motor speed and bus voltage. It then controls the drive motor to operate at the corresponding heating power, so that the heat lost by the drive motor is transferred to the power battery, allowing the battery temperature to rise.

[0004] However, the above method involves pre-calibrating the relationship between speed, voltage, and heating power, and then determining the heating power of the drive motor by looking up a table. This method cannot accurately meet the heating requirements of the power battery, resulting in low heating efficiency of the power battery. Summary of the Invention

[0005] This application provides a heating method, apparatus, electronic device, and vehicle for a power battery. An offset angle can be determined based on the difference between the real-time heating power and the required heating power of the power battery. Then, by adjusting the electrical angle of the stator current of the drive motor based on this offset angle, the losses of the drive motor can be increased, thereby increasing the heat generation of the drive motor and ultimately improving the heating efficiency of the power battery. The technical solution includes the following:

[0006] In a first aspect, a method for heating a power battery is provided, the method comprising: The current heating power of the drive motor is determined based on the current operating parameters of the vehicle's drive motor, the current charge level of the power battery, and the required temperature. If the current heating power does not meet the heating requirements of the power battery, a target offset angle is determined based on the difference between the current heating power and the required heating power of the power battery. The target offset angle is used to increase the losses of the drive motor. Based on the target offset angle, the electrical angle of the stator current of the drive motor is adjusted to increase the heat generation of the drive motor and transfer the heat generated by the drive motor to the power battery to heat the power battery.

[0007] In this application, the current heating power of the drive motor is first determined based on the current operating parameters of the vehicle's drive motor, the current charge level of the power battery, and the required temperature. Then, if the current heating power does not meet the heating requirements of the power battery, a target offset angle is determined based on the difference between the current heating power and the required heating power of the power battery. Finally, based on the target offset angle, the electrical angle of the stator current of the drive motor is adjusted. This is equivalent to first determining a current heating power that matches the vehicle's current operating conditions based on the vehicle's operating and state parameters in various dimensions. Then, if the current heating power does not meet the heating requirements of the power battery, the electrical angle of the stator current of the drive motor is adjusted to increase the drive motor's losses (such as iron losses), thereby increasing the heat generation of the drive motor. Compared to the existing technology that determines the heating power based on voltage and speed tables, this solution can increase motor losses based on the required heating power of the power battery and accurately change the motor's heat generation in real time according to the actual situation, thereby improving the motor's heating efficiency. This allows for precise response to the heating requirements of the power battery, thus improving the heating efficiency of the power battery.

[0008] Optionally, the current operating parameters include the current motor speed, current required torque, and current operating current; determining the current heating power of the drive motor based on the current operating parameters of the vehicle's drive motor, the current charge level of the power battery, and the required temperature includes: The current motor speed, current required torque, current operating current of the drive motor, current charge level of the power battery, and required temperature are used as input parameters and input into the objective function. The objective function is used to represent the relationship between the motor speed, required torque, and operating current of the drive motor, the charge level of the power battery, the required temperature, and the motor heating power. Based on the objective function, the current heating power of the drive motor corresponding to the input parameters is calculated.

[0009] In the above method, the objective function is used to represent the relationship between the motor speed, required torque and operating current of the drive motor, the power battery charge, the required temperature and the motor heating power. This allows the current heating power of the drive motor under the corresponding operating conditions to be obtained directly based on the objective function, thereby improving the accuracy and efficiency of determining the current heating power.

[0010] Optionally, the step of determining the objective function includes: Obtain a target mapping table, which includes multiple correspondences. These correspondences represent the relationships between different motor speeds, different required torques, different operating currents, different current battery levels, different required temperatures, and different motor heating powers. The multiple correspondences in the target mapping table are obtained from historical heating data when the drive motor heats the power battery. The objective function is obtained by fitting multiple correspondences in the target mapping table.

[0011] In the above method, by obtaining multiple correspondences from the historical heating data of the drive motor heating the power battery, it is possible to first obtain the motor heating power corresponding to different motor speeds, different required torques, different operating currents, different charge levels, and different required temperatures. This motor heating power is a heating power that fits the corresponding vehicle operating conditions. Then, based on this, the objective function is fitted, so that the correlation between these parameters and the motor heating power can be accurately determined from these multiple real correspondences, thereby fitting a more accurate objective function.

[0012] Optionally, determining the target offset angle based on the difference between the current heating power and the required heating power of the power battery includes: Subtract the required heating power from the current heating power to obtain the power demand difference; The initial offset angle is determined based on the power demand difference and the first gain coefficient; The offset error is determined based on the power demand difference and the second gain coefficient; The target offset angle is obtained by adding the offset error to the initial offset angle.

[0013] In the above method, the initial offset angle is first determined based on the first gain coefficient, and the offset error is determined based on the second gain coefficient. Then, the target offset angle is determined by adding the offset error to the initial offset angle. This is equivalent to correcting the initial offset angle through the offset error, thereby obtaining a more accurate target offset angle. In this way, the actual heating power of the drive motor can meet the heating requirements of the power battery.

[0014] Optionally, adjusting the electrical angle of the stator current of the drive motor based on the target offset angle includes: Based on the current motor speed of the drive motor, determine the current electrical angle of the stator current; When the direct-axis current corresponding to the stator current is positive, the target offset angle is subtracted from the current electrical angle to reduce the current electrical angle. The direct-axis current is the current component of the stator current on the direct axis in the dq coordinate system. When the direct-axis current corresponding to the stator current is negative, the target offset angle is added to the current electrical angle to increase the current electrical angle.

[0015] In the above methods, whether the current electrical angle is reduced or increased, the essence is to make the phase angle between the stator magnetic field and the rotor magnetic field deviate from the optimal angle during normal operation. This will either cause the magnetic field to be excessively superimposed, leading to magnetic circuit saturation, or cause the magnetic field to be decoupled, leading to coupling failure. Ultimately, the torque is maintained by "increasing the current" or "exacerbating the magnetic field fluctuations". All these additional energy consumptions will be converted into motor heat, thereby precisely increasing the heat generation power of the drive motor.

[0016] Optionally, before determining the target offset angle based on the difference between the current heating power and the required heating power of the power battery when the current heating power does not meet the heating requirements of the power battery, the method further includes: Obtain the stator temperature of the drive motor; If the stator temperature of the motor is greater than or equal to the safe temperature threshold, reduce the motor heating power of the drive motor. If the motor stator temperature is lower than the safe temperature threshold, determine whether the current heating power meets the heating requirements of the power battery.

[0017] In the above method, to avoid motor overheating and failure that could affect the vehicle's normal driving safety, the stator temperature of the motor is also checked to see if it has reached a set safe temperature threshold. If the stator temperature has reached the set safe temperature threshold, the heating power of the drive motor needs to be reduced to prevent overheating failure. However, if the stator temperature has not reached the set safe temperature threshold, it indicates that the heating power of the drive motor can be further increased. In this case, it can be further determined whether the current heating power meets the heating requirements of the power battery. If the current heating power does not meet the heating requirements of the power battery, the heating power of the drive motor can be increased.

[0018] Optionally, reducing the motor heating power of the drive motor when the motor stator temperature is greater than or equal to a safe temperature threshold includes: When the stator temperature of the motor is greater than or equal to the safe temperature threshold, the target current value is determined based on the current heating power and maximum heating power of the drive motor. The target current value is subtracted from the direct-axis current corresponding to the stator current to reduce the motor heating power of the drive motor.

[0019] In the above method, to reduce the motor heating power, it is necessary to reduce motor losses. This is achieved by reducing the direct-axis current, which distributes the current to the quadrature-axis current that directly generates torque (as the direct-axis current decreases, the quadrature-axis current increases). This brings the current distribution closer to the efficient range, reducing ineffective current consumption for excitation, improving motor efficiency, and thus reducing overall power consumption. Consequently, motor losses are reduced, achieving the effect of efficiently reducing heating power.

[0020] Optionally, determining the target current value based on the current heating power and maximum heating power of the drive motor includes: The target power difference is obtained by subtracting the current heating power of the drive motor from the maximum heating power. The initial current value is determined based on the target power difference and the third gain coefficient; The current error value is determined based on the target power difference and the fourth gain coefficient; The target current value is obtained by adding the initial current value to the current error value.

[0021] In the above method, the initial current value is first determined based on the third gain coefficient, and then the current error value is determined based on the fourth gain coefficient. The target current value is then determined by adding the current error value to the initial current value. This is equivalent to correcting the initial current value through the current error, thereby obtaining a more accurate target current value. As a result, the actual heating power of the drive motor can be effectively reduced.

[0022] Secondly, a heating device for a power battery is provided, the device comprising: The first determining module is used to determine the current heating power of the drive motor based on the current operating parameters of the vehicle's drive motor, the current charge level of the power battery, and the required temperature. The second determining module is used to determine a target offset angle based on the difference between the current heating power and the required heating power of the power battery when the current heating power does not meet the heating requirements of the power battery. The target offset angle is used to increase the loss of the drive motor. The adjustment module is used to adjust the electrical angle of the stator current of the drive motor based on the target offset angle, so as to increase the heat generation of the drive motor and transfer the heat generated by the drive motor to the power battery to heat the power battery.

[0023] Optionally, the current operating parameters include the current motor speed, the current required torque, and the current operating current; the first determining module is used for: The current motor speed, current required torque, current operating current of the drive motor, current charge level of the power battery, and required temperature are used as input parameters and input into the objective function. The objective function is used to represent the relationship between the motor speed, required torque, and operating current of the drive motor, the charge level of the power battery, the required temperature, and the motor heating power. Based on the objective function, the current heating power of the drive motor corresponding to the input parameters is calculated.

[0024] Optionally, the apparatus further includes: a function determination module, which is used to: Obtain a target mapping table, which includes multiple correspondences. These correspondences represent the relationships between different motor speeds, different required torques, different operating currents, different current battery levels, different required temperatures, and different motor heating powers. The multiple correspondences in the target mapping table are obtained from historical heating data when the drive motor heats the power battery. The objective function is obtained by fitting multiple correspondences in the target mapping table.

[0025] Optionally, the second determining module is used to: Subtract the required heating power from the current heating power to obtain the power demand difference; The initial offset angle is determined based on the power demand difference and the first gain coefficient; The offset error is determined based on the power demand difference and the second gain coefficient; The target offset angle is obtained by adding the offset error to the initial offset angle.

[0026] Optionally, the adjustment module is used for: Based on the current motor speed of the drive motor, determine the current electrical angle of the stator current; When the direct-axis current corresponding to the stator current is positive, the target offset angle is subtracted from the current electrical angle to reduce the current electrical angle. The direct-axis current is the current component of the stator current on the direct axis in the dq coordinate system. When the direct-axis current corresponding to the stator current is negative, the target offset angle is added to the current electrical angle to increase the current electrical angle.

[0027] Optionally, the device further includes: The acquisition module is used to acquire the stator temperature of the drive motor; A power reduction module is used to reduce the motor heating power of the drive motor when the motor stator temperature is greater than or equal to a safe temperature threshold. The judgment module is used to determine whether the current heating power meets the heating requirements of the power battery when the motor stator temperature is lower than the safe temperature threshold.

[0028] Optionally, the power reduction module is specifically used for: When the stator temperature of the motor is greater than or equal to the safe temperature threshold, the target current value is determined based on the current heating power and maximum heating power of the drive motor. The target current value is subtracted from the direct-axis current corresponding to the stator current to reduce the motor heating power of the drive motor.

[0029] Optionally, the power reduction module is specifically used for: The target power difference is obtained by subtracting the current heating power of the drive motor from the maximum heating power. The initial current value is determined based on the target power difference and the third gain coefficient; The current error value is determined based on the target power difference and the fourth gain coefficient; The target current value is obtained by adding the initial current value to the current error value.

[0030] Thirdly, an electronic device for a vehicle is provided, the electronic device comprising: Memory, used to store executable program code; A processor is configured to call and run the executable program code from the memory, causing the electronic device to perform the aforementioned heating method for the power battery.

[0031] Fourthly, a vehicle is provided, the vehicle comprising: Memory, used to store executable program code; A processor is configured to call and run the executable program code from the memory, causing the vehicle to perform the aforementioned power battery heating method.

[0032] Fifthly, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described heating method for a power battery.

[0033] Sixthly, a computer program product containing instructions is provided, which, when run on a computer, causes the computer to perform the steps of the above-described heating method for a power battery.

[0034] It is understood that the beneficial effects of the second, third, fourth, fifth, and sixth aspects mentioned above can be found in the relevant descriptions in the first aspect above, and will not be repeated here. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of a drive motor provided in an embodiment of this application; Figure 2 This is a flowchart of a heating method for a power battery provided in an embodiment of this application; Figure 3 This is a flowchart of another heating method for a power battery provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a heating device for a power battery provided in an embodiment of this application; Figure 5 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0038] It should be understood that "multiple" as mentioned in this application refers to two or more. In the description of this application, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist, for example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, to facilitate a clear description of the technical solutions of this application, the terms "first," "second," etc., are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, and that "first," "second," etc., do not necessarily imply differences.

[0039] The working principle of the drive motor involved in the embodiments of this application will be explained first.

[0040] For example, Figure 1 This is a schematic diagram of the structure of a drive motor provided in an embodiment of this application.

[0041] In this embodiment of the application, the drive motor can be a permanent magnet synchronous motor, such as... Figure 1 As shown, the drive motor may include a stator 101, a rotor 102, and an end cover 103.

[0042] Among them, stator 101 is the stationary component of the permanent magnet synchronous motor, corresponding to Figure 1 The stator 101 has an external fixed part with heat dissipation fins, which includes a stator core and a stator winding. The stator winding is embedded in the stator core. By passing three-phase alternating current to the stator winding, the stator 101 can generate a rotating magnetic field.

[0043] The rotor 102 is the core component of the permanent magnet synchronous motor. Permanent magnet poles are mounted on the rotor 102, protruding outwards and embedded in the outer side of the rotor core, forming several pairs of magnetic poles. The permanent magnet poles can generate a strong and stable magnetic field without the need for electricity.

[0044] End caps 103 are components at both ends of the permanent magnet synchronous motor used to support the bearings and protect the internal structure.

[0045] During the operation of the permanent magnet synchronous motor, the stator 101 generates a rotating magnetic field through three-phase alternating current, while the rotor 102 uses permanent magnets to generate a stationary magnetic field. The rotating stator magnetic field drags the stationary rotor magnetic field along with it, and the rotor speed is synchronized with the stator magnetic field speed. During motor operation, the torque and speed of the motor can be precisely controlled by adjusting the strength, direction, and frequency of the stator magnetic field based on actual needs.

[0046] Generally, independent, precise, and rapid decoupling control of torque and magnetic field is achieved based on Field-Oriented Control (FOC) algorithms. Because the three-phase stator currents of an AC motor have a strong coupling relationship, torque and magnetic flux interfere with each other, making precise control difficult. The core of FOC is to transform the current in the three-phase stationary coordinate system to the dq coordinate system, which rotates synchronously with the rotor magnetic field, through coordinate transformations (mainly Clark and Park transformations). This transforms the complex AC quantity control into independently adjustable DC quantities, enabling subsequent independent control of the motor's magnetic field and torque.

[0047] (1) Clark Transform In the Clark transformation, the main function is to convert the currents (ia, ib, ic) in the three-phase stationary coordinate system into a two-phase stationary coordinate system. Current in coordinate system and In this conversion, the main focus is on simplifying the dimensions, transforming the current dimension from three-phase to two-phase. The specific conversion process can be achieved using the following formula (1).

[0048] (1) (2) Park Transform In the Park transform, the main function is to transform two stationary phases... The current in the coordinate system is converted into the current in a two-phase rotating dq coordinate system synchronized with the rotor magnetic field. , , , Let dq be a direct volume, where the dq coordinate system includes the direct axis and the intersection axis. This refers to the current along the direct axis (d-axis), which is used to control the magnetic field strength of the motor. The current on the quadrature axis (q-axis) is used to control the magnitude of the motor output torque. The specific conversion process can be achieved through the following formula (2). After conversion, the direct-axis current is obtained. and cross-axis current Subsequently, closed-loop regulation can be performed on the direct-axis current and quadrature-axis current respectively to achieve independent control of torque and magnetic flux.

[0049] (2) in, The rotor flux position angle is the spatial electrical angle of the flux vector generated by the rotor permanent magnet in the three-phase stationary coordinate system.

[0050] The application scenarios of the embodiments of this application are described below.

[0051] In low-temperature environments, the charging and discharging efficiency of the power battery decreases, making it unable to efficiently discharge to the drive motor. This results in low operating efficiency and insufficient output torque for the drive motor, thus affecting the vehicle's driving performance. Therefore, it is necessary to increase the temperature of the power battery in low-temperature environments.

[0052] One heating method for power batteries in related technologies involves installing a PTC (Positive Temperature Coefficient) heater in the vehicle's heat exchange circuit. The battery management system monitors the battery cell temperature, current battery charge, and ambient temperature in real time. When these parameters meet the heating conditions for the power battery, the PTC heater is activated to generate heat, which is then transferred to the power battery through the heat exchange system, allowing the battery temperature to rise.

[0053] However, in the above methods, if the power battery needs to heat up quickly, the PTC heater needs to be controlled to work at a higher power to generate more heat. However, this will result in the vehicle having high energy consumption but low heating efficiency.

[0054] Because motors generate some losses during operation, and the lost energy is released in the form of heat, active heating solutions based on motor losses have emerged in related technologies.

[0055] One type of active heating method for motors involves the motor controller obtaining the corresponding heating power from a pre-calibrated speed-voltage-heating power relationship table based on the current motor speed and bus voltage. The controller then controls the drive motor to operate at the corresponding heating power, so that the heat loss of the drive motor is transferred to the power battery, thereby raising the temperature of the power battery.

[0056] Another active heating method for motors in related technologies involves maintaining the quadrature-axis current to meet the vehicle's power requirements during the field-oriented control process. This is achieved by increasing the preset stator current on the direct axis, causing the motor's magnetic field to saturate or deviate from the optimal excitation state. This increases the heat generated by the motor's losses, which is then transferred to the power battery through a heat exchange system, thereby achieving the purpose of raising the temperature of the power battery.

[0057] However, the above two methods have the following problems: (1) When the relationship between speed, voltage, and heating power is pre-calibrated, and the heating power of the drive motor is determined by looking up a table, the actual operating conditions of the vehicle are dynamic, such as rapid acceleration, rapid deceleration, and constant speed driving. The motor operates differently under different operating conditions, and the corresponding heating power will also vary. Therefore, the heating power determined in this way may not match the heating requirements of the power battery, resulting in a slower heating of the power battery.

[0058] (2) When the direct axis current is increased, the direct axis current and the quadrature axis current are coupled and interfered in actual control. For example, when the direct axis current is increased, the magnetic flux state of the motor will be changed, which will affect the control accuracy of the quadrature axis current on the torque, resulting in fluctuations in the torque output.

[0059] Therefore, this application provides a method for heating a power battery, which can be applied to scenarios where the power battery is heated by an active heating method based on a motor in a low-temperature environment.

[0060] Specifically, the system first acquires the operating parameters of the drive motor across various dimensions, including torque request, speed, and current control in the field-oriented control (FOC). It also acquires the state parameters of the power battery, such as current charge level and required temperature. Based on these parameters, the system determines the current heating power suitable for the vehicle's current operating conditions. Next, it compares the current heating power with the required heating power of the power battery. If the current heating power does not meet the battery's heating needs, the system determines the electrical angle that increases motor losses based on the difference between the two. The stator current is then adjusted accordingly to further increase motor losses. This adjustment of the electrical angle precisely modifies motor losses to generate heat based on actual heating requirements, thereby improving motor heating efficiency and enabling a precise response to the power battery's heating needs, allowing the battery temperature to rise rapidly.

[0061] The heating method for the power battery provided in the embodiments of this application will be explained in detail below.

[0062] Figure 2 This is a flowchart illustrating a heating method for a power battery according to an embodiment of this application. This method can be applied to the motor control unit (MCU) of a vehicle's drive motor. See also... Figure 2 The method includes the following steps.

[0063] Step 201: Determine the current heating power of the drive motor based on the current operating parameters of the vehicle's drive motor, the current charge level of the power battery, and the required temperature.

[0064] The current operating parameters of the drive motor are used to represent the operating status of the drive motor under the current operating conditions of the vehicle. They comprehensively represent the operating status of the drive motor through operating parameters across multiple dimensions. In this embodiment, the current operating parameters may include the current motor speed, the current required torque, and the current operating current. The current required torque refers to the motor output torque determined based on the driver's requirements. The current operating current is the direct-axis current and quadrature-axis current of the specified sub-current (three-phase AC) after Clark and Park transformations in the dq coordinate system.

[0065] In this embodiment, the current heating power is also the current loss power of the drive motor. Since the drive motor will have losses such as copper loss, iron loss, and mechanical loss during operation, and these losses are dissipated in the form of heat energy, the solution of heating the power battery based on the active heating of the motor is to use the heat generated by the loss to heat the power battery. Therefore, the current loss power of the drive motor can be regarded as the current heating power.

[0066] Since the current operating parameters of the drive motor are parameters that comprehensively represent the operating status of the drive motor from multiple dimensions, they can indicate the actual operating status of the drive motor under a certain operating condition. Therefore, in the above method, determining the current heating power based on the current operating parameters of the drive motor, the current charge level of the power battery, and the required temperature is equivalent to determining the actual heating power of the drive motor that matches the current operating condition and battery state by considering the actual operating status of the drive motor under a certain operating condition and the actual state of the power battery. This allows for the determination of an actual heating power that more closely reflects the actual operating condition, thus achieving a more accurate determination of the current heating power.

[0067] One possible approach is to perform step 201 as follows: input the current motor speed of the drive motor, the current required torque, the current operating current, the current charge of the power battery, and the required temperature as input parameters into the objective function; and calculate the current heating power of the drive motor corresponding to the input parameters based on the objective function.

[0068] The objective function represents the relationship between the motor speed, required torque and operating current of the drive motor, the power battery charge, the required temperature and the motor heating power.

[0069] It should be understood that the losses of the drive motor should differ under different motor speeds, required torques, and operating currents (including direct-axis and quadrature-axis currents). Furthermore, there may be a correlation between motor speed, required torque, operating current, and motor losses; for example, higher motor speeds may generally lead to higher motor losses. Additionally, the required heating power should also differ depending on the battery charge and required battery temperature, resulting in varying motor losses. Therefore, during the heating process of the battery at different charge levels and required temperatures, the drive motor's speed, required torque, and operating current should be correlated with the motor's heating power; that is, there should be a corresponding correlation between the drive motor's speed, required torque, operating current, the battery's charge level, required temperature, and the motor's heating power.

[0070] In the above method, the objective function is used to represent the relationship between the motor speed, required torque and operating current of the drive motor, the power battery charge, the required temperature and the motor heating power. This allows the current heating power of the drive motor under the corresponding operating conditions to be obtained directly based on the objective function, thereby improving the accuracy and efficiency of determining the current heating power.

[0071] For example, the above method is to calculate the current heating power of the drive motor based on the current motor speed, current required torque, current operating current, current power charge and required temperature of the power battery using the following formula (3).

[0072] (3) in, This represents the current heating power of the drive motor. This refers to the real-time power loss of the drive motor. For the current required torque, The current motor speed is given by, where, , This is the current operating current. Let the three-phase alternating current be the direct-axis current in the dq coordinate system. The quadrature-axis current of three-phase alternating current in the dq coordinate system The required temperature for the power battery is given by [value], and the current charge level (SOC) of the power battery is given by [value]. The objective function is denoted as .

[0073] In one possible implementation, the objective function can be determined based on the operating parameters of the drive motor, the state parameters of the power battery, and the corresponding heating power during the historical process of the drive motor actively heating the power battery.

[0074] Specifically, the steps for determining the objective function can be as follows: obtain an objective mapping table, which includes multiple correspondences. These multiple correspondences are used to represent the correspondences between different motor speeds, different required torques, different operating currents, different current power levels, different required temperatures, and different motor heating powers; and fit the objective function based on the multiple correspondences in the objective mapping table.

[0075] Each of these multiple correspondences includes a motor speed, a required torque, an operating current, a current battery level, a required temperature, and a motor heating power. The motor heating power is the heating power of the drive motor corresponding to the motor speed, required torque, operating current, current battery level, and required temperature when heating the power battery. In other words, it is the heating power that matches the vehicle operating conditions indicated by the motor speed, required torque, operating current, current battery level, and required temperature.

[0076] The multiple correspondences in the target mapping table can be obtained from the historical heating data of the drive motor heating the power battery. This historical heating data can include the historical operating parameters of the drive motor, the historical state parameters of the power battery, and the corresponding motor heating power (i.e., power loss) during the heating process. The historical operating parameters are the motor speed, required torque, and operating current of the drive motor at different times during the historical heating process. The historical state parameters can be the power battery's charge level and required temperature at the corresponding time during the historical heating process.

[0077] After obtaining historical heating data, the motor speed, required torque, operating current, power battery charge and required temperature obtained at the same time can be used as a set of correspondences with the motor heating power at that time. Then, multiple correspondences can be obtained between the motor speed, required torque, operating current, power battery charge and required temperature obtained at different times and the motor heating power at the corresponding time.

[0078] In the above method, by obtaining multiple correspondences from the historical heating data of the drive motor heating the power battery, it is possible to first obtain the motor heating power corresponding to different motor speeds, different required torques, different operating currents, different charge levels, and different required temperatures. This motor heating power is a heating power that fits the corresponding vehicle operating conditions. Then, based on this, the objective function is fitted, so that the correlation between these parameters and the motor heating power can be accurately determined from these multiple real correspondences, thereby fitting a more accurate objective function.

[0079] The operation of fitting the target function based on multiple correspondences in the target mapping table includes, but is not limited to, methods based on mathematical functions or neural network models, and the embodiments of this application do not limit this.

[0080] For example, we can assume an initial relation, which can be a multivariate nonlinear function; then we can substitute the multiple correspondences into the initial relation, solve the coefficients in the initial relation using the weighted least squares method, and substitute each coefficient into the initial relation to obtain the functional relation corresponding to the objective function.

[0081] Step 201 above describes the specific operation of determining the current heating power of the drive motor. In this embodiment, after determining the current heating power of the drive motor, the stator temperature of the drive motor can be obtained first; if the stator temperature is greater than or equal to the safe temperature threshold, the heating power of the drive motor is reduced.

[0082] Only when the stator temperature of the motor is below the safe temperature threshold can it be determined whether the current heating power of the drive motor meets the heating requirements of the power battery.

[0083] The safe temperature threshold refers to the stator temperature at which the drive motor can operate safely. The safe temperature threshold can be preset, for example, it can be set to 130℃ (degrees Celsius).

[0084] During the operation of the drive motor, the motor losses increase, the stator temperature rises, and heat generation increases, posing a risk of motor overheating and failure. In this embodiment, to avoid motor overheating failure affecting the normal driving safety of the vehicle, the stator temperature of the motor is also detected to see if it reaches a set safe temperature threshold. If the stator temperature has reached the set safe temperature threshold, the motor heating power of the drive motor needs to be reduced to prevent motor overheating failure.

[0085] However, if the electronic stator temperature does not reach the set safe temperature threshold, it means that the heating power of the drive motor can be further increased. In this case, it can be further determined whether the current heating power meets the heating requirements of the power battery. If the current heating power does not meet the heating requirements of the power battery, the motor heating power of the drive motor can be increased.

[0086] The following section will introduce specific methods for reducing the motor heating power of the drive motor when the motor stator temperature is greater than or equal to the safe temperature threshold.

[0087] One possible approach is to reduce the motor heating power of the drive motor when the motor stator temperature is greater than or equal to the safe temperature threshold. This can be achieved by: determining a target current value based on the current and maximum heating power of the drive motor when the motor stator temperature is greater than or equal to the safe temperature threshold; and subtracting the target current value from the direct-axis current corresponding to the stator current to reduce the motor heating power of the drive motor.

[0088] The maximum heating power refers to the maximum heating power corresponding to the current motor stator temperature. It should be understood that the maximum heating power varies depending on the motor stator temperature. In this embodiment, a target correspondence can be established to indicate the maximum heating power corresponding to different motor stator temperatures. After obtaining the motor stator temperature, the maximum heating power corresponding to that temperature can be obtained from the target correspondence. Furthermore, when the motor stator temperature reaches a safe temperature threshold, it indicates that the heating power has exceeded the maximum heating power corresponding to that motor stator temperature, therefore the motor heating power needs to be reduced.

[0089] The target current value is the direct-axis current in the dq coordinate system, and the target current is the calculated direct-axis current to be reduced.

[0090] To reduce the motor's heating power, it is necessary to reduce motor losses. The above method involves reducing the direct-axis current to distribute current to the quadrature-axis current that directly generates torque (as the direct-axis current decreases, the quadrature-axis current increases). This brings the current distribution closer to the efficient range, reducing ineffective current consumption for excitation, improving motor efficiency, and thus reducing overall power consumption and ultimately motor losses.

[0091] The operation of determining the target current value based on the current heating power and maximum heating power of the drive motor can be as follows: subtract the current heating power of the drive motor from the maximum heating power to obtain the target power difference; determine the initial current value based on the target power difference and the third gain coefficient; determine the current error value based on the target power difference and the fourth gain coefficient; and add the current error value to the initial current value to obtain the target current value.

[0092] The third gain coefficient is the proportional gain in the direct-axis current control process. It is used to represent the proportional relationship between the heating power deviation and the current control value. The unit is (amperes / kilowatts). For example, for every 1 kilowatt deviation of the motor heating power from the set value (which can be considered as the maximum heating power) by 1 kilowatt, the corresponding change in direct-axis current is shown.

[0093] The fourth gain coefficient represents the integral gain during the direct-axis current control process, indicating the proportional relationship between the current reduction and the accumulated error. The third gain coefficient is used to eliminate steady-state error during the direct-axis current control process. Since a fixed difference (steady-state error) may exist between the actual measured value and the set value of the heating power after the entire control process reaches a steady state, this difference is eliminated by setting the fourth gain coefficient, resulting in a more accurate target current value. In this embodiment, the third and fourth gain coefficients can be pre-calibrated by a technician.

[0094] In this case, after obtaining the target power difference in the above steps, the target power difference can be multiplied by the third gain coefficient to obtain the initial current value, which is the direct-axis current that should be reduced according to the proportional gain under this target power difference (initial current value). Then, the integral value of the target power difference over one time period is calculated. This integral value can represent the cumulative power error over this time period. Then, this integral value is multiplied by the fourth gain coefficient to obtain the cumulative current error (current error value). Then, the initial current value is corrected by the current error value, that is, the initial current value is added to the current error value to obtain a more accurate target current value.

[0095] In the above method, the initial current value is first determined based on the third gain coefficient, and then the current error value is determined based on the fourth gain coefficient. The target current value is then determined by adding the current error value to the initial current value. This is equivalent to correcting the initial current value through the current error, thereby obtaining a more accurate target current value. As a result, the actual heating power of the drive motor can be effectively reduced.

[0096] It is worth noting that the specific steps for determining the target current value based on the current heating power and the maximum heating power of the drive motor are also the process of determining the target current value based on the difference between the current heating power and the maximum heating power through PI control, which is the process of calculating the target current value through the following formula (4).

[0097] (4) in, For the target current value, This is the third gain coefficient. This is the fourth gain coefficient. The maximum heating power corresponding to the stator temperature of the motor is given by t, which is a time period. This time period can be the adjustment period of the PI controller, which is synchronized with the switching period of the PWM wave (Pulse Width Modulation).

[0098] It should be noted that the core of FOC control is to decompose the three-phase AC power into direct-axis current I through coordinate transformation. d and quadrature axis current I q Then, two independent PI controllers are used to adjust these two currents respectively, making them track the target value, and finally outputting a direct-axis voltage V through the PI controller. d Cross-axis voltage V q Two voltage signals are used to control the motor, and the PI output V d V q The two voltage signals need to be converted into three-phase voltages through inverse transformation, and then the PWM wave is used to drive power devices such as MOSFETs and IGBTs to control the drive motor. Here, the switching frequency of the PWM wave refers to the number of times the power device switches per second, and its reciprocal is the switching period t. In this case, by synchronizing the adjustment period of the PI controller with the switching period of the PWM wave, it can be ensured that the adjusted direct-axis current can be fed back to the next cycle in a timely manner, thereby acting on the drive motor promptly and avoiding adjustment delay.

[0099] It is worth noting that in the embodiments of this application, the direct-axis current corresponding to the stator current is the direct-axis current of the stator current in the dq coordinate system calculated based on the MTPA (Maximum Torque Per Ampere) algorithm. That is, it is the direct-axis current that allows the motor to output the maximum torque with the minimum current. Subsequently, a certain current value (target current value) is reduced based on this direct-axis current to achieve the purpose of reducing the heating power.

[0100] The following explains the specific method for determining whether the current heating power of the drive motor meets the heating requirements of the power battery when the stator temperature of the motor is lower than the safe temperature threshold.

[0101] In one possible scenario, when the battery management system detects that the ambient temperature is below a certain temperature threshold, it can determine that the power battery needs to be heated. In this case, the battery management system can send a heating request to the MCU of the drive motor. The heating request can carry parameters such as the required heating power, required heating temperature, and current battery level of the power battery, so that the MCU can adjust the heating power accordingly to heat the power battery.

[0102] Another possible scenario is that after the MCU determines the current heating power, it can send a request to the battery management system to obtain the required heating power. After receiving the request, the battery management system can return the current required heating power of the power battery to the MCU.

[0103] Based on this, it can be determined whether the current heating power of the drive motor meets the heating requirements of the power battery by considering the current heating power of the drive motor and the required heating power of the power battery.

[0104] Specifically, the operation of determining whether the current heating power of the drive motor meets the heating requirements of the power battery can be as follows: if the current heating power of the drive motor is less than the required heating power of the power battery, and the absolute value of the difference between the current heating power and the required heating power is greater than a preset difference threshold, it is determined that the current heating power of the drive motor does not meet the heating requirements of the power battery; if the absolute value of the difference between the current heating power and the required heating power is less than or equal to the preset difference threshold, it is determined that the current heating power of the drive motor meets the heating requirements of the power battery; if the current heating power of the drive motor is greater than or equal to the required heating power of the power battery, it is determined that the current heating power of the drive motor meets the heating requirements of the power battery.

[0105] The preset difference threshold can be set in advance, and the preset difference threshold can be set to a relatively small value.

[0106] It should be understood that when the current heating power of the drive motor is greater than or equal to the required heating power, it means that the current heating power is large enough to meet the heating requirements of the power battery.

[0107] When the current heating power of the drive motor is less than the required heating power, it means that the current heating power of the drive motor is too small. However, if the current heating power is close to the required heating power, the current heating power can also meet the heating requirements of the power battery. But when the current heating power is much less than the required heating power, it means that the current heating power of the drive motor is too small and cannot meet the heating requirements of the power battery.

[0108] Therefore, if the absolute value of the difference between the current heating power and the required heating power is less than or equal to a preset difference threshold, it indicates that the current heating power is close to the required heating power, thus confirming that the current heating power meets the heating requirements of the power battery. Conversely, if the absolute value of the difference between the current heating power and the required heating power is greater than the preset difference threshold, it indicates that the difference is significant, meaning the current heating power is much less than the required heating power, thus confirming that the current heating power does not meet the heating requirements of the power battery.

[0109] It is worth noting that, in this embodiment, by comparing the current heating power of the drive motor with the required heating power of the power battery, it can be determined whether the current heating power meets the heating requirements of the power battery. If the current heating power meets the heating requirements of the power battery, the heating power of the drive motor does not need to be adjusted. However, if the current heating power does not meet the heating requirements of the power battery, the heating power of the drive motor needs to be adjusted subsequently, that is, steps 202 and 203 below can be executed.

[0110] Step 202: If the current heating power does not meet the heating requirements of the power battery, a target offset angle is determined based on the difference between the current heating power and the required heating power of the power battery. The target offset angle is used to increase the loss of the drive motor.

[0111] The target offset angle is the electrical angle of the stator current. The electrical angle of the stator current refers to the direction of the stator magnetic field in space. Specifically, the electrical angle of the stator current refers to the position in space pointed to by the rotating magnetomotive force vector (stator magnetic field) synthesized by the three-phase current at a certain moment. It is essentially a spatial angle that determines the phase angle between the stator magnetic field and the rotor magnetic field. The stator magnetic field is the magnetic field generated by the stator after the stator winding is energized.

[0112] Under normal circumstances, the phase angle between the stator magnetic field and the rotor magnetic field is at an optimal angle. However, if the phase angle between the stator magnetic field and the rotor magnetic field deviates by a certain angle, it will break the ideal matching state between the stator magnetic field and the rotor magnetic field, thereby increasing the motor loss.

[0113] In the above method, a target offset angle is determined based on the difference between the current heating power and the required heating power of the power battery. This is equivalent to determining an electrical angle that can match the required heating power of the power battery. Subsequently, by offsetting the electrical angle of the stator current by a corresponding angle, the phase angle between the stator magnetic field and the rotor magnetic field is not the optimal angle, thereby generating corresponding heat. This improves the heating power of the drive motor, enabling the heating power of the drive motor to meet the heating requirements of the power battery.

[0114] One possible approach is to perform step 202 as follows: subtract the required heating power from the current heating power to obtain the power demand difference; determine the initial offset angle based on the power demand difference and the first gain coefficient; determine the offset error based on the power demand difference and the second gain coefficient; and add the offset error to the initial offset angle to obtain the target offset angle.

[0115] The first gain coefficient is the proportional gain in the electric angle control process. It is used to represent the proportional relationship between the deviation of the motor heating power and the electric angle offset angle. The unit is (degrees / kilowatt). For example, for every kilowatt deviation of the motor heating power from the set value (which can be considered as the required heating power of the power battery) by 1 kilowatt, the corresponding electric angle should be offset by an angle.

[0116] The second gain coefficient is the integral gain in the electrical angle control process, which represents the proportional relationship between the electrical angle offset and the accumulated error. The second gain coefficient is used to eliminate the steady-state error generated during heating power control. Since, when calculating the output offset angle solely using the aforementioned proportional gain, a fixed difference (steady-state error) may exist between the actual measured value and the set value of the heating power after the entire control process reaches a steady state, a second gain coefficient is set here to eliminate this difference, resulting in a more accurate target offset. In this embodiment, the first and second gain coefficients can be pre-calibrated by a technician.

[0117] In this case, after obtaining the power demand difference in the above steps, the power demand difference can be multiplied by the first gain coefficient to obtain the initial offset angle, which is the angle that the electrical angle should offset according to the proportional gain under this power demand difference. Then, the integral value of the power demand difference over a time period is calculated. This integral value can represent the cumulative error over this time period. Then, the integral value is multiplied by the second gain coefficient to obtain the offset error. The initial offset angle is then corrected by the offset error, that is, the initial offset angle is added to the offset error to obtain a more accurate target offset angle.

[0118] In the above method, the initial offset angle is first determined based on the first gain coefficient, and the offset error is determined based on the second gain coefficient. Then, the target offset angle is determined by adding the offset error to the initial offset angle. This is equivalent to correcting the initial offset angle through the offset error, thereby obtaining a more accurate target offset angle. In this way, the actual heating power of the drive motor can meet the heating requirements of the power battery.

[0119] It is worth noting that the specific steps of step 202 above are the process of determining the target offset angle based on the difference between the current heating power and the required heating power through PI control, which is the process of calculating the target offset angle through the following formula (5).

[0120] (5) in, The target offset angle, The first gain coefficient, This is the second gain coefficient. The required heating power for the power battery is given by t, which is a time period. This time period can be the adjustment period of the PI controller, which is synchronized with the switching period of the PWM wave.

[0121] In this way, by synchronizing the adjustment cycle of the PI controller with the switching cycle of the PWM wave, it can be ensured that the target offset angle calculated during the electrical angle control process can be fed back to the next cycle in a timely manner, thereby acting on the drive motor in a timely manner and avoiding adjustment delay.

[0122] Step 203: Based on the target offset angle, adjust the electrical angle of the stator current of the drive motor to increase the heat generation of the drive motor and transfer the heat generated by the drive motor to the power battery to heat the power battery.

[0123] During normal operation of a drive motor, the stator magnetic field maintains an optimal phase angle with the rotor magnetic field, resulting in the highest magnetic field utilization and minimum losses. To increase the losses of the drive motor, a target offset angle is determined, and the electrical angle of the stator current is adjusted to create a "mismatch" between the stator and rotor magnetic fields. This generates additional useless magnetic fields or increases current redundancy. When the drive motor operates under these conditions, losses increase, leading to higher power consumption and thus increased heating power, resulting in more heat generation.

[0124] One possible approach is to perform step 203 as follows: determine the current electrical angle of the stator current based on the current motor speed of the drive motor; when the direct-axis current corresponding to the stator current is positive, subtract the target offset angle from the current electrical angle to reduce the current electrical angle; when the direct-axis current corresponding to the stator current is negative, add the target offset angle to the current electrical angle to increase the current electrical angle.

[0125] Generally, the electrical angle of the stator current determines the phase angle between the stator magnetic field and the rotor magnetic field. Therefore, there is a certain relationship between the phase angle between the stator magnetic field and the rotor magnetic field and the electrical angle of the stator current. Typically, they are positively correlated; that is, the larger the electrical angle of the stator current, the larger the phase angle between the stator magnetic field and the rotor magnetic field, and vice versa. In this embodiment, to achieve a "mismatch" between the stator magnetic field and the rotor magnetic field, the electrical angle of the stator current can be adjusted.

[0126] It should be understood that when the direct-axis current corresponding to the stator current is positive, the stator magnetic field has a magnetizing effect. In this case, reducing the phase angle between the stator and rotor magnetic fields is equivalent to reducing the angle between them, resulting in excessive magnetic field overlap and exacerbating magnetic circuit saturation. After magnetic circuit saturation, to maintain the target torque, the total stator current needs to be increased to generate sufficient electromagnetic induction. However, with increased current, copper losses are proportional to the square of the current, thus increasing copper losses accordingly. Furthermore, after magnetic circuit saturation, the magnetic flux density in the core increases significantly, and since iron losses are proportional to the square of the magnetic flux density, this further increases iron losses. Therefore, when the direct-axis current corresponding to the stator current is positive, the phase angle between the stator and rotor magnetic fields can be reduced by decreasing the current electrical angle, thereby increasing motor losses.

[0127] When the direct-axis current corresponding to the stator current is negative, the stator magnetic field has a demagnetizing effect. Increasing the phase angle between the stator and rotor magnetic fields at this time will increase the angle between them. The stator magnetic field will not only fail to assist the rotor magnetic field but will also exert a "resistive" demagnetizing effect, significantly reducing electromagnetic coupling efficiency. After the coupling efficiency decreases, maintaining the original torque requires a significant increase in the total stator current. This quadratic increase in the total current will directly lead to a sharp rise in copper losses. Furthermore, when the phase angle is too large, the direction of the stator magnetic field frequently deviates from the optimal coupling direction of the rotor magnetic field, causing high-frequency fluctuations in the direction and density of magnetic flux in the core. Simultaneously, the "alternating reversal" of the magnetic field during demagnetization will exacerbate iron losses. Therefore, when the direct-axis current corresponding to the stator current is negative, increasing the current electrical angle can increase the phase angle between the stator and rotor magnetic fields, thereby increasing motor losses.

[0128] In the above methods, whether the current electrical angle is reduced or increased, the essence is to make the phase angle between the stator magnetic field and the rotor magnetic field deviate from the optimal angle during normal operation. This will either cause the magnetic field to be excessively superimposed, leading to magnetic circuit saturation, or cause the magnetic field to be decoupled, leading to coupling failure. Ultimately, the torque is maintained by "increasing the current" or "exacerbating the magnetic field fluctuations". All these additional energy consumptions will be converted into motor heat, thereby precisely increasing the heat generation power of the drive motor.

[0129] The operation of determining the current electrical angle of the stator current based on the current motor speed of the drive motor can be as follows: based on the current motor speed, obtain the corresponding electrical angle from the preset mapping relationship and determine it as the current electrical angle.

[0130] The preset mapping relationship is used to indicate the optimal electrical angle of the stator current at different motor speeds. This optimal electrical angle is the electrical angle that achieves maximum torque output with minimum current.

[0131] The preset mapping relationship includes multiple motor speeds and multiple optimal electrical angles. Each motor speed corresponds to an optimal electrical angle. This optimal electrical angle is used to represent the electrical angle at which the drive motor outputs the maximum torque with the minimum current at this motor speed. In other words, by setting the electrical angle of the stator current at this optimal electrical angle, the drive motor can achieve the maximum torque output with the minimum current, and at this time, the loss is minimized.

[0132] Since different motor speeds correspond to different load conditions, and the optimal electrical angle changes with the load torque, different optimal electrical angles are set for different motor speeds to ensure maximum torque output. In this case, during motor operation, the optimal electrical angle is obtained based on different motor speeds. Then, by maintaining the electrical angle of the stator current at this angle, the current electrical angle of the stator current is the optimal electrical angle corresponding to the current motor speed.

[0133] In the above method, the current electrical angle is determined by directly obtaining the corresponding optimal electrical angle from the preset mapping relationship based on the current motor speed, thereby quickly determining the current electrical angle of the stator current and improving the efficiency of determining the current electrical angle of the stator current.

[0134] Since the electrical angle of the stator current is determined by the current distribution ratio on the direct and quadrature axes, when adjusting the electrical angle of the stator current, the current distribution ratio on the direct and quadrature axes can be redefined based on the final electrical angle obtained by subtracting the target offset angle from the current electrical angle, or the final electrical angle obtained by adding the target offset angle to the current electrical angle. Then, based on the redefined current distribution ratio on the subsequent quadrature axis, the target direct-axis current and the target quadrature-axis current are determined. Finally, the direct-axis current is adjusted by the PI controller corresponding to the direct-axis current based on the target direct-axis current, and the quadrature-axis current is adjusted by the PI controller corresponding to the quadrature-axis current based on the target quadrature-axis current, thus achieving the purpose of adjusting the current electrical angle.

[0135] It is worth noting that after adjusting the electrical angle of the stator current of the drive motor based on the target offset angle, the current heating power of the drive motor can be determined based on the operation in step 201, and it can be determined whether the current heating power of the drive motor after the electrical angle adjustment has met the heating requirements of the power battery. That is, it can be determined whether the absolute value of the difference between the current heating power and the required heating power of the power battery is less than a preset difference threshold. In this embodiment, if the absolute value of the difference between the current heating power and the required heating power of the power battery is still greater than the preset difference threshold, it is necessary to continue to execute the above steps 201-203 to adjust the electrical angle of the stator current of the drive motor to continue to increase motor losses and increase the motor heating power of the drive motor. However, if the absolute value of the difference between the current heating power and the required heating power of the power battery is less than or equal to the preset difference threshold, it is not necessary to adjust the electrical angle of the stator current of the drive motor, that is, it is not necessary to increase the motor heating power of the drive motor.

[0136] It is worth noting that, in this embodiment, when there is a risk of overheating in the drive motor, by reducing the magnitude of the direct-axis current in the dq coordinate system, the distribution ratio of the quadrature-axis current is improved. This allows for maintaining power output while reducing the current, thereby achieving dual-objective optimization of heating and power, and achieving an optimal balance between heating efficiency and power output. Furthermore, heating requirements vary under different ambient temperatures. By adjusting motor losses to adjust the heating power, the range of heating power adjustment is expanded to cover heating requirements under different ambient temperatures.

[0137] Furthermore, experiments have shown that the power battery heating solution provided in this application, in terms of 0℃ cold start time, achieves a cold start in only 9 minutes, compared to 22 minutes for existing solutions. Secondly, the energy consumption per 100 kilometers in existing technologies under low-temperature conditions is 19.8 kWh, while this solution reduces it to 16.3 kWh, an improvement of 17.7%. Thirdly, the energy recovery rate under low-temperature conditions is 68% in existing technologies, while this solution achieves 81%, an improvement of 19%. Finally, the torque fluctuation rate during power battery heating in existing technologies reaches 5.2%, while this solution only has 1.8%, an improvement of 65%.

[0138] To facilitate understanding, we will now combine... Figure 3 The overall flow of the heating method for the power battery provided in the embodiments of this application will be described. For example, Figure 3 This is a flowchart of another heating method for a power battery provided in an embodiment of this application.

[0139] Step 301: Obtain the current operating parameters of the drive motor, the current charge level of the power battery, and the required temperature.

[0140] Step 302: Determine the current heating power of the drive motor.

[0141] Step 303: Obtain the stator temperature of the drive motor.

[0142] Step 304: Determine if the motor stator temperature has reached the safe temperature threshold. If the motor stator temperature has not reached the safe temperature threshold, continue with steps 307-309 to increase motor losses and heat generation. If the motor stator temperature has reached the safe temperature threshold, continue with steps 305 and 306.

[0143] Step 305: Determine the target current value based on the current heating power and maximum heating power of the drive motor.

[0144] Step 306: Subtract the target current value from the direct-axis current corresponding to the stator current to reduce the motor heating power of the drive motor.

[0145] Step 307: Determine whether the current heating power meets the heating requirements of the power battery.

[0146] Step 308: If the current heating power does not meet the heating requirements of the power battery, determine the target offset angle based on the difference between the current heating power and the required heating power of the power battery.

[0147] Step 309: Based on the target offset angle, adjust the electrical angle of the stator current of the drive motor.

[0148] In this embodiment, the MCU first determines the current heating power of the drive motor based on the current operating parameters of the vehicle's drive motor, the current charge level of the power battery, and the required temperature. Then, if the current heating power does not meet the heating requirements of the power battery, a target offset angle is determined based on the difference between the current heating power and the required heating power of the power battery. Finally, based on the target offset angle, the electrical angle of the stator current of the drive motor is adjusted. This is equivalent to first determining a current heating power that matches the vehicle's current operating conditions based on the vehicle's operating and state parameters in various dimensions. Then, if the current heating power does not meet the heating requirements of the power battery, the electrical angle of the stator current of the drive motor is adjusted to increase the drive motor's losses (such as iron losses), thereby increasing the heat generation of the drive motor. Compared to the existing technology that determines the heating power based on voltage and speed lookup tables, this solution can increase motor losses based on the required heating power of the power battery and accurately change the motor's heat generation in real time according to the actual situation, thereby improving the motor's heating efficiency. This allows for precise response to the heating requirements of the power battery, thus improving the heating efficiency of the power battery.

[0149] Figure 4 This is a schematic diagram of the structure of a heating device for a power battery according to an embodiment of this application. The heating device for the power battery can be implemented by software, hardware, or a combination of both, and can be part or all of a vehicle, which can be described below. Figure 5 The vehicle shown. See also Figure 4 The device includes: a first determining module 401, a second determining module 402, and an adjusting module 403.

[0150] The first determining module 401 is used to determine the current heating power of the drive motor based on the current operating parameters of the vehicle's drive motor, the current charge of the power battery, and the required temperature. The second determining module 402 is used to determine a target offset angle based on the difference between the current heating power and the required heating power of the power battery when the current heating power does not meet the heating requirements of the power battery. The target offset angle is used to increase the loss of the drive motor. The adjustment module 403 is used to adjust the electrical angle of the stator current of the drive motor based on the target offset angle, so as to increase the heat generation of the drive motor and transfer the heat generated by the drive motor to the power battery to heat the power battery.

[0151] Optionally, the current operating parameters include the current motor speed, the current required torque, and the current operating current; the first determining module 401 is used for: The current motor speed, current required torque, current operating current, current battery charge, and required temperature of the drive motor are used as input parameters and input into the objective function. The objective function is used to represent the relationship between the motor speed, required torque, operating current of the drive motor, battery charge, required temperature, and motor heating power. Based on the objective function, calculate the current heating power of the drive motor corresponding to the input parameters.

[0152] Optionally, the apparatus further includes: a function determination module, which is used for: Obtain the target mapping table, which includes multiple correspondences. These correspondences represent the relationships between different motor speeds, different required torques, different operating currents, different current battery levels, different required temperatures, and different motor heating powers. The multiple correspondences in the target mapping table are obtained from historical heating data when the drive motor heats the power battery. The objective function is obtained by fitting multiple correspondences in the target mapping table.

[0153] Optionally, the second determining module 402 is used for: Subtract the required heating power from the current heating power to obtain the power demand difference; The initial offset angle is determined based on the power demand difference and the first gain coefficient; The offset error is determined based on the power demand difference and the second gain coefficient; Add the offset error to the initial offset angle to obtain the target offset angle.

[0154] Optionally, the adjustment module 403 is used for: Based on the current motor speed of the drive motor, determine the current electrical angle of the stator current; When the direct-axis current corresponding to the stator current is positive, the target offset angle is subtracted from the current electrical angle to reduce the current electrical angle. The direct-axis current is the current component of the stator current on the direct axis in the dq coordinate system. When the direct-axis current corresponding to the stator current is negative, the target offset angle is added to the current electrical angle to increase the current electrical angle.

[0155] Optionally, the device further includes: The acquisition module is used to acquire the stator temperature of the drive motor; The power reduction module is used to reduce the motor heating power of the drive motor when the motor stator temperature is greater than or equal to the safe temperature threshold. The judgment module is used to determine whether the current heating power meets the heating requirements of the power battery when the motor stator temperature is lower than the safe temperature threshold.

[0156] Optionally, the power reduction module is specifically used for: When the stator temperature of the motor is greater than or equal to the safe temperature threshold, the target current value is determined based on the current heating power and maximum heating power of the drive motor. The target current value is subtracted from the direct-axis current corresponding to the stator current to reduce the motor heating power of the drive motor.

[0157] Optionally, the power reduction module is specifically used for: The target power difference is obtained by subtracting the current heating power of the drive motor from the maximum heating power. The initial current value is determined based on the target power difference and the third gain coefficient; The current error value is determined based on the target power difference and the fourth gain coefficient; The target current value is obtained by adding the current error value to the initial current value.

[0158] In this embodiment, the current heating power of the drive motor is first determined based on the current operating parameters of the vehicle's drive motor, the current charge level of the power battery, and the required temperature. Then, if the current heating power does not meet the heating requirements of the power battery, a target offset angle is determined based on the difference between the current heating power and the required heating power of the power battery. Finally, the electrical angle of the stator current of the drive motor is adjusted based on the target offset angle. In essence, this involves first determining a current heating power that matches the vehicle's current operating conditions based on the vehicle's operating and state parameters across various dimensions. Then, if the current heating power does not meet the heating requirements of the power battery, the electrical angle of the stator current of the drive motor is adjusted to increase the drive motor's losses (such as iron losses), thereby increasing the heat generation of the drive motor. Compared to the existing method of determining heating power based on voltage and speed tables, this solution can increase motor losses based on the required heating power of the power battery and accurately adjust the motor's heat generation in real time according to actual conditions, thereby improving the motor's heating efficiency. This allows for precise response to the heating requirements of the power battery, resulting in improved heating efficiency.

[0159] It should be noted that the heating device for the power battery provided in the above embodiments is only illustrated by the division of the above functional modules. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0160] The functional units and modules in the above embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of the embodiments of this application.

[0161] The heating device for the power battery and the heating method for the power battery provided in the above embodiments belong to the same concept. For the specific working process and technical effects of the units and modules in the above embodiments, please refer to the method embodiments section, which will not be repeated here.

[0162] Figure 5 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application.

[0163] For example, such as Figure 5 As shown, the vehicle 500 includes a memory 51 and a processor 50, wherein the memory 51 stores executable program code 52, and the processor 50 is used to call and execute the executable program code 52 to perform the above-mentioned heating method for a power battery.

[0164] This embodiment can divide the vehicle into functional modules according to the above method example. For example, each function can be assigned to a separate module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0165] When each functional module is divided according to its corresponding function, the vehicle may include: a first determining module, a second determining module, and an adjusting module. It should be noted that all relevant content regarding the steps involved in the above method embodiments can be referenced from the functional descriptions of the corresponding functional modules, and will not be repeated here.

[0166] The vehicle provided in this embodiment is used to perform the above-described heating method for a power battery, and therefore can achieve the same effect as the above-described implementation method.

[0167] When using integrated units, the vehicle may include a processing module and a storage module. The processing module is used to control and manage the vehicle's actions. The storage module is used to support the vehicle in executing corresponding program code and data.

[0168] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits shown in conjunction with the disclosure of this application. The processor may also be a combination of functions that implement computing capabilities, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0169] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement the above-described method for heating a power battery.

[0170] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned related steps to implement the above-described method for heating a power battery.

[0171] In this embodiment, the vehicle, computer-readable storage medium, computer program product, or chip are all used to execute the method described above. Therefore, the beneficial effects that can be achieved can be referred to the beneficial effects of the method described above, and will not be repeated here.

[0172] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0173] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are illustrative; for instance, the division of modules or units is merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0174] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of heating a power cell, characterized by, The method comprises: determining a current heating power of the drive motor based on current operating parameters of the drive motor, a current power level of the power battery and a required temperature of the power battery; in a case where the current heating power does not meet the heating requirement of the power battery, determining a target offset angle based on a difference between the current heating power and a required heating power of the power battery, the target offset angle being used to increase the loss of the drive motor; adjusting an electrical angle of the stator current of the drive motor based on the target offset angle to increase the heat generation of the drive motor and transfer the heat generated by the drive motor to the power battery to heat the power battery.

2. The method of claim 1, wherein, The current operating parameters include a current motor speed, a current required torque and a current operating current; and the determination of the current heating power of the drive motor based on the current operating parameters of the drive motor, the current power level of the power battery and the required temperature of the power battery comprises: inputting the current motor speed, the current required torque, the current operating current, the current power level of the power battery and the required temperature of the power battery as input parameters into a target function, the target function being used to represent the correlation between the motor speed, the required torque and the operating current of the drive motor, the power level and the required temperature of the power battery and the motor heating power; calculating the current heating power of the drive motor corresponding to the input parameters based on the target function.

3. The method of claim 2, wherein, The determination of the target function comprises: obtaining a target mapping table, the target mapping table comprising a plurality of corresponding relationships, the plurality of corresponding relationships being used to represent the corresponding relationships between different motor speeds, different required torques, different operating currents, different current power levels and different required temperatures and different motor heating powers, the plurality of corresponding relationships in the target mapping table being obtained from historical heating data when the drive motor heats the power battery; fitting the target function based on the plurality of corresponding relationships in the target mapping table.

4. The method of claim 1, wherein, The determination of the target offset angle based on the difference between the current heating power and the required heating power of the power battery comprises: subtracting the required heating power from the current heating power to obtain a power requirement difference; determining an initial offset angle based on the power requirement difference and a first gain coefficient; determining an offset error based on the power requirement difference and a second gain coefficient; adding the initial offset angle to the offset error to obtain the target offset angle.

5. The method of claim 1, wherein, The adjustment of the electrical angle of the stator current of the drive motor based on the target offset angle comprises: determining a current electrical angle of the stator current based on the current motor speed of the drive motor; when a direct-axis current corresponding to the stator current is positive, subtracting the target offset angle from the current electrical angle to reduce the current electrical angle, the direct-axis current being a current component of the stator current on a direct axis in a dq coordinate system; when the direct-axis current corresponding to the stator current is negative, adding the target offset angle to the current electrical angle to increase the current electrical angle.

6. The method according to any one of claims 1 to 5, wherein, Before the determining the target offset angle based on a difference between the current heating power and a required heating power of the power battery, the method further includes: obtaining a motor stator temperature of the driving motor; decreasing a motor heating power of the driving motor when the motor stator temperature is greater than or equal to a safety temperature threshold; judging whether the current heating power meets a heating requirement of the power battery when the motor stator temperature is less than the safety temperature threshold.

7. The method of claim 6, wherein, The decreasing the motor heating power of the driving motor when the motor stator temperature is greater than or equal to the safety temperature threshold includes: determining a target current value based on a current heating power and a maximum heating power of the driving motor when the motor stator temperature is greater than or equal to the safety temperature threshold; subtracting the target current value from a direct-axis current corresponding to the stator current to decrease the motor heating power of the driving motor.

8. The method of claim 7, wherein, The determining the target current value based on the current heating power and the maximum heating power of the driving motor includes: subtracting the current heating power of the driving motor from the maximum heating power to obtain a target power difference value; determining an initial current value based on the target power difference value and a third gain coefficient; determining a current error value based on the target power difference value and a fourth gain coefficient; adding the initial current value and the current error value to obtain the target current value.

9. An electronic device of a vehicle, characterized by comprising: The electronic device includes: a memory configured to store executable program code; a processor configured to call and run the executable program code from the memory, so that the electronic device performs the method according to any one of claims 1 to 8.

10. A vehicle characterized by comprising: The vehicle includes: a memory configured to store executable program code; a processor configured to call and run the executable program code from the memory, so that the vehicle performs the method according to any one of claims 1 to 8.

Images