Torque control method, device, vehicle and storage medium

Abstract

The application relates to the technical field of new energy vehicles, in particular to a torque control method and device, a vehicle and a storage medium, wherein the method comprises the following steps: acquiring a current voltage of a high-voltage battery and a current temperature of a motor stator; calculating a current temperature of a motor rotor according to the current temperature of the motor stator and an equivalent thermal network model of the motor rotor; taking the current voltage and the current temperature of the motor rotor as indexes, querying an efficiency table of a motor drive system corresponding to the indexes, and determining a current efficiency of the motor drive system; calculating a motor drive request torque of the motor drive system according to the current efficiency, and controlling the motor drive system to execute the motor drive request torque so as to provide power for the whole vehicle or realize energy recovery. Therefore, the problems that the actual efficiency of the motor drive system is greatly different from the calibrated efficiency, the actual power consumption of the battery in the motor mode exceeds the maximum allowable discharging power of the battery, and the actual charging power in the energy recovery mode exceeds the maximum allowable charging power of the high-voltage battery are solved.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, specifically to a torque control method, device, vehicle, and storage medium. Background Technology

[0002] With the rapid development and popularization of electric vehicles, torque control strategies for high-voltage electrical components in electric vehicles are becoming increasingly important. The electric drive system, as a crucial driving force component of electric vehicles, not only provides power to the entire vehicle but also recovers energy to charge the battery during braking and coasting.

[0003] Traditional electric vehicle torque control strategies calculate the requested torque of the motor based on acquired signals. This calculation utilizes an efficiency map of the electric drive system, representing the results of bench tests. However, due to the inherent characteristics of components such as magnets and silicon steel sheets, the efficiency of the electric drive system is affected by temperature. Furthermore, changes in the remaining battery charge during driving cause variations in the input voltage of the electric drive system, which significantly impacts its efficiency. Therefore, in actual electric vehicle use, these factors inevitably lead to a difference between the electric drive system's efficiency and the predetermined efficiency map calibration value.

[0004] With the current control method, when the actual efficiency of the electric drive system is significantly lower than the efficiency in the current query map table, the DC bus will consume more power for the same amount of power consumed at the mechanical end. This will further cause the actual power consumed by the battery to exceed the maximum allowable discharge power of the battery. Similarly, under energy recovery conditions, when the actual efficiency of the electric drive system is significantly lower than the efficiency in the current query map table, the charging power at the DC bus will be greater, which may cause the actual charging power to exceed the maximum allowable charging power of the battery and affect the battery's lifespan. Summary of the Invention

[0005] One objective of this invention is to provide a torque control method to solve the problem that the actual efficiency of the electric drive system in the prior art differs greatly from the calibrated efficiency, resulting in the actual power consumption of the battery in electric mode exceeding the maximum allowable discharge power of the battery, and the actual charging power in energy recovery mode exceeding the maximum allowable charging power of the high-voltage battery; a second objective is to provide a torque control device; a third objective is to provide a vehicle; and a fourth objective is to provide a computer-readable storage medium.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A torque control method includes the following steps: obtaining the current voltage of a high-voltage battery and the current temperature of a motor stator; calculating the current temperature of the motor rotor based on the current temperature of the motor stator and an equivalent thermal network model of the motor rotor; querying an efficiency table of the electric drive system corresponding to the current voltage and the current temperature of the motor rotor using the current voltage and the current temperature of the motor rotor as indices; determining the current efficiency of the electric drive system based on the efficiency table; calculating the electric drive requested torque of the electric drive system based on the current efficiency; and controlling the electric drive system to execute the electric drive requested torque to provide power to the vehicle or achieve energy recovery.

[0008] Based on the above technical means, the embodiments of this application can calculate the current temperature of the motor rotor based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor, determine the efficiency table corresponding to the electric drive system based on the current voltage of the high-voltage battery and the current temperature of the motor rotor, further determine the current efficiency of the electric drive system, take into account the influence of different battery voltages and different motor rotor temperatures on the efficiency of the electric drive system, reduce the difference between the actual efficiency and the calibrated efficiency value of the electric drive system, control the electric drive system to execute the electric drive request torque calculated based on the current efficiency, and realize the provision of power to the whole vehicle or the realization of energy recovery.

[0009] Furthermore, the step of calculating the electric drive requested torque of the electric drive system based on the current efficiency includes: obtaining the allowable power of the electric drive system and the vehicle's required torque; calculating the allowable torque of the electric drive system based on the current efficiency and the allowable power; and determining the electric drive requested torque based on the allowable torque, the vehicle's required torque, and the maximum torque of the electric drive system.

[0010] Based on the above technical means, the embodiments of this application can calculate the allowable torque of the electric drive system based on the current efficiency and allowable power of the electric drive system, and further determine the electric drive requested torque based on the allowable torque, the vehicle's required torque and the maximum torque of the electric drive system.

[0011] Furthermore, obtaining the permissible power of the electric drive system includes: obtaining the maximum permissible discharge power of the high-voltage battery and the power of the high-voltage accessory; and calculating the permissible power of the electric drive system based on the maximum permissible discharge power and the power of the high-voltage accessory.

[0012] Based on the above technical means, the embodiments of this application can calculate the allowable power of the electric drive system based on the maximum allowable discharge power of the high-voltage battery and the power of the high-voltage accessories.

[0013] Furthermore, determining the electric drive requested torque based on the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system includes: if the vehicle is in electric operating condition, then the minimum value among the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system is used as the electric drive requested torque; if the vehicle is in energy recovery operating condition, then the maximum value among the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system is used as the electric drive requested torque.

[0014] Based on the above technical means, the embodiments of this application can determine the electric drive requested torque according to different operating conditions of the vehicle, and take into account the overcharging problem of high-voltage battery in different modes.

[0015] Furthermore, controlling the electric drive system to execute the electric drive requested torque includes: if the electric drive requested torque is the allowable torque, controlling the electric drive system to execute the electric drive requested torque based on the difference between the actual power of the electric drive system and the allowable power; if the electric drive requested torque is the vehicle's required torque or the maximum torque of the electric drive system, then controlling the electric drive system to execute the electric drive requested torque.

[0016] Based on the above technical means, the embodiments of this application can further determine how to control the electric drive system to execute the electric drive requested torque by judging the relationship between the electric drive requested torque and the allowable torque, the vehicle demand torque, and the maximum torque of the electric drive system.

[0017] Further, controlling the electric drive system to execute the requested electric drive torque based on the difference between the actual power of the electric drive system and the allowable power includes: if the difference is a preset value, then executing the requested electric drive torque; if the difference is greater than the preset value, then determining a first efficiency of the electric drive system based on an efficiency table corresponding to the next temperature range of the current voltage and the current temperature, and redetermining the requested electric drive torque based on the first efficiency; if the difference is less than the preset value, then determining a second efficiency of the electric drive system based on an efficiency table corresponding to the previous temperature range of the current voltage and the current temperature, and redetermining the requested electric drive torque based on the second efficiency.

[0018] Based on the above technical means, the embodiments of this application can determine the magnitude of the electric drive requested torque according to the relationship between the difference between the actual power and the allowable power of the electric drive system and a preset value.

[0019] Furthermore, the torque control method further includes: if the efficiency table is the efficiency table corresponding to the highest temperature range, then the electric drive requested torque is corrected according to the portion of the actual power exceeding the allowable power; if the efficiency table is the efficiency table corresponding to the lowest temperature range, then the electric drive requested torque is corrected according to the portion of the actual power lower than the allowable power.

[0020] Based on the above technical means, the embodiments of this application can modify the electric drive requested torque according to the relationship between the actual power and the allowable power of the electric drive system.

[0021] Furthermore, determining the current efficiency of the electric drive system based on the efficiency table includes: obtaining the current speed and current torque of the motor; and querying the efficiency table using the current speed and current torque as indexes to obtain the current efficiency of the electric drive system.

[0022] Based on the above technical means, the embodiments of this application can obtain the current efficiency of the electric drive system by querying the current speed and current torque of the motor.

[0023] Furthermore, before querying the efficiency table of the electric drive system corresponding to the current voltage and the current temperature, the method further includes: dividing the voltage range of the high-voltage battery into multiple voltages at equal intervals; dividing the temperature range of the motor rotor into multiple temperature intervals; calibrating the efficiency of the electric drive system under different voltages and different temperature intervals according to the multiple voltages and the multiple temperature intervals, and obtaining efficiency tables under different temperature intervals and different voltages.

[0024] Based on the above technical means, the embodiments of this application can divide the voltage range of the high-voltage battery and the temperature range of the motor rotor into multiple voltage and multiple temperature ranges, respectively, calibrate the efficiency of the electric drive system under different voltage and different temperature ranges, and generate an efficiency table so that the efficiency of the corresponding electric drive system can be determined in the subsequent process based on the efficiency table.

[0025] Furthermore, calibrating the efficiency of the electric drive system under different voltages and temperature ranges based on the plurality of voltages and the plurality of temperature ranges includes: performing drive and power generation efficiency tests on the electric drive system under each temperature range and each voltage; collecting the rotational speed and torque during the test of the drive system; calculating the efficiency corresponding to each rotational speed and torque based on the voltage, current, rotational speed, and torque; and generating an efficiency table of the electric drive system based on each rotational speed, each torque, and the corresponding efficiency.

[0026] Based on the above technical means, the embodiments of this application can perform drive and power generation efficiency tests on the electric drive system in each temperature range and at each voltage range, collect the speed and torque during the test, and further calculate the corresponding efficiency based on voltage, current, speed and torque to establish an efficiency table of the electric drive system, taking into account the influence of different voltages and different rotor temperatures on the efficiency of the electric drive system.

[0027] Furthermore, the step of calculating the current temperature of the motor rotor based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor further includes: obtaining the initial temperature, rotational speed, and torque of the motor rotor, as well as the temperature of the motor windings, and calculating the losses of the motor rotor based on the rotational speed and torque of the motor rotor; inputting the current temperature of the motor stator, the initial temperature of the motor rotor, the temperature of the motor windings, and the losses of the motor rotor into the equivalent thermal network model, and the equivalent thermal network model outputting the current temperature of the motor rotor.

[0028] Based on the above technical means, the embodiments of this application can output the current temperature of the motor rotor by establishing an equivalent thermal network model of the motor rotor.

[0029] A torque control device includes: an acquisition module for acquiring the current voltage of a high-voltage battery and the current temperature of a motor stator; a determination module for calculating the current temperature of the motor rotor based on the current temperature of the motor stator and an equivalent thermal network model of the motor rotor, querying an efficiency table of the electric drive system corresponding to the current voltage and the current temperature of the motor rotor as an index, and determining the current efficiency of the electric drive system based on the efficiency table; and a control module for calculating the electric drive requested torque of the electric drive system based on the current efficiency, and controlling the electric drive system to execute the electric drive requested torque to provide power to the vehicle or achieve energy recovery.

[0030] Furthermore, the control module is further configured to: acquire the allowable power of the electric drive system and the vehicle's required torque; calculate the allowable torque of the electric drive system based on the current efficiency and the allowable power; and determine the electric drive requested torque based on the allowable torque, the vehicle's required torque, and the maximum torque of the electric drive system.

[0031] Furthermore, the control module is further configured to: obtain the maximum allowable discharge power of the high-voltage battery and the power of the high-voltage accessory; and calculate the allowable power of the electric drive system based on the maximum allowable discharge power and the power of the high-voltage accessory.

[0032] Furthermore, the control module is further configured to: if the vehicle is in electric operating condition, use the minimum value among the allowable torque, the vehicle required torque, and the maximum torque of the electric drive system as the electric drive requested torque; if the vehicle is in energy recovery operating condition, use the maximum value among the allowable torque, the vehicle required torque, and the maximum torque of the electric drive system as the electric drive requested torque.

[0033] Furthermore, the control module is further configured to: if the electric drive requested torque is the allowable torque, control the electric drive system to execute the electric drive requested torque based on the difference between the actual power of the electric drive system and the allowable power; if the electric drive requested torque is the vehicle's required torque or the maximum torque of the electric drive system, control the electric drive system to execute the electric drive requested torque.

[0034] Furthermore, the control module is further configured to: if the difference is a preset value, then execute the electric drive request torque; if the difference is greater than the preset value, then determine the first efficiency of the electric drive system according to the efficiency table corresponding to the next temperature range of the current voltage and the current temperature, and redetermine the electric drive request torque according to the first efficiency; if the difference is less than the preset value, then determine the second efficiency of the electric drive system according to the efficiency table corresponding to the previous temperature range of the current voltage and the current temperature, and redetermine the electric drive request torque according to the second efficiency.

[0035] Furthermore, the torque control device further includes: a correction module, configured to correct the electric drive requested torque based on the portion of the actual power exceeding the allowable power if the efficiency table corresponds to the highest temperature range; and to correct the electric drive requested torque based on the portion of the actual power lower than the allowable power if the efficiency table corresponds to the lowest temperature range.

[0036] Furthermore, the determining module is further configured to: obtain the current speed and current torque of the motor; and use the current speed and current torque as indexes to query the efficiency table to obtain the current efficiency of the electric drive system.

[0037] Furthermore, the torque control device also includes: a calibration module, used to divide the voltage range of the high-voltage battery into multiple voltages at equal intervals before querying the efficiency table of the electric drive system corresponding to the current voltage and the current temperature; divide the temperature range of the motor rotor into multiple temperature intervals; and calibrate the efficiency of the electric drive system under different voltages and different temperature intervals according to the multiple voltages and the multiple temperature intervals to obtain efficiency tables under different temperature intervals and different voltages.

[0038] Furthermore, the calibration module is further configured to: perform drive and power generation efficiency tests on the electric drive system at each temperature range and at each voltage; collect the speed and torque during the test of the drive system, calculate the efficiency corresponding to each speed and torque based on the voltage, current, speed and torque; and generate an efficiency table of the electric drive system based on each speed, each torque and the corresponding efficiency.

[0039] Furthermore, the determining module is further configured to: obtain the initial temperature, speed, and torque of the motor rotor and the temperature of the motor windings, and calculate the losses of the motor rotor based on the speed and torque of the motor rotor; input the current temperature of the motor stator, the initial temperature of the motor rotor, the temperature of the motor windings, and the losses of the motor rotor into the equivalent thermal network model, and the equivalent thermal network model outputs the current temperature of the motor rotor.

[0040] A vehicle includes: an electric drive system; and a vehicle controller configured to acquire the current voltage of a high-voltage battery and the current temperature of a motor rotor, query an efficiency table of the electric drive system corresponding to the current voltage and the current temperature using the current voltage and the current temperature as indexes, determine the current efficiency of the electric drive system based on the efficiency table, calculate the electric drive requested torque of the electric drive system based on the current efficiency, and control the electric drive system to execute the electric drive requested torque to provide power to the vehicle or achieve energy recovery.

[0041] A computer-readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the torque control method described in the above embodiments.

[0042] The beneficial effects of this invention are:

[0043] (1) In this embodiment, the current temperature of the motor rotor can be calculated based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor. Based on the current voltage of the high-voltage battery and the current temperature of the motor rotor, the efficiency table corresponding to the electric drive system is determined, and the current efficiency of the electric drive system is further determined. The influence of different battery voltages and different motor rotor temperatures on the efficiency of the electric drive system is taken into account, the difference between the actual efficiency and the calibrated efficiency value of the electric drive system is reduced, and the electric drive system is controlled to execute the electric drive request torque calculated based on the current efficiency, so as to provide power to the whole vehicle or realize energy recovery.

[0044] (2) The embodiments of this application can calculate the allowable torque of the electric drive system based on the current efficiency and allowable power of the electric drive system, and further determine the electric drive requested torque based on the allowable torque, the vehicle demand torque and the maximum torque of the electric drive system.

[0045] (3) The allowable power of the electric drive system can be calculated based on the maximum allowable discharge power of the high voltage battery and the power of the high voltage accessory in this embodiment.

[0046] (4) The embodiments of this application can determine the electric drive requested torque according to the different working conditions of the vehicle and take into account the overcharging problem of high voltage battery under different modes.

[0047] (5) The embodiments of this application can determine how to control the electric drive system to execute the electric drive requested torque by judging the relationship between the electric drive requested torque and the allowable torque, the vehicle demand torque and the maximum torque of the electric drive system.

[0048] (6) The present application embodiment can determine the magnitude of the electric drive requested torque based on the relationship between the difference between the actual power and the allowable power of the electric drive system and the preset value.

[0049] (7) The embodiments of this application can correct the electric drive requested torque by the relationship between the actual power and the allowable power of the electric drive system.

[0050] (8) The current efficiency of the electric drive system can be obtained by querying the current speed and current torque of the motor in this embodiment of the application.

[0051] (9) In this embodiment of the application, the voltage range of the high-voltage battery and the temperature range of the motor rotor can be divided into multiple voltage and multiple temperature ranges, respectively, and the efficiency of the electric drive system under different voltage and different temperature ranges can be calibrated to generate an efficiency table so that the efficiency of the corresponding electric drive system can be determined according to the efficiency table.

[0052] (10) The embodiments of this application can test the driving and power generation efficiency of the electric drive system in each temperature range and at each voltage range and at each voltage range, collect the speed and torque during the test, and further calculate the corresponding efficiency based on the voltage, speed and torque to establish an efficiency table of the electric drive system, taking into account the influence of different voltages and different rotor temperatures on the efficiency of the electric drive system.

[0053] (11) The embodiments of this application can output the current temperature of the motor rotor by establishing an equivalent thermal network model of the motor rotor.

[0054] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of high-voltage electrical appliances in related technologies;

[0056] Figure 2 This is a flowchart of the torque control method in this invention;

[0057] Figure 3 This is a schematic diagram of the rotor temperature change curve during natural cooling in this invention;

[0058] Figure 4 This is the logic diagram for calculating the electric drive torque in electric mode in this invention;

[0059] Figure 5 This is a flowchart of the electric vehicle drive torque control strategy in this invention;

[0060] Figure 6 This is the electric drive torque calculation logic in the braking mode of this invention;

[0061] Figure 7 This is a flowchart of the electric vehicle regenerative torque control strategy in this invention.

[0062] Figure 8 This is a schematic diagram of the torque control device in this invention;

[0063] Figure 9 This is a schematic diagram of the vehicle structure in this invention. Detailed Implementation

[0064] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0065] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0066] The related technology discloses a power distribution method and system for electric vehicles, which to some extent solves the problem that the actual power consumption of the battery exceeds the maximum allowable discharge power of the battery due to the discrepancy between the actual efficiency and the rated efficiency of the electric drive system. Under energy recovery conditions, the actual charging power exceeds the maximum allowable charging power of the battery, which affects the battery life. Figure 1 This is a schematic diagram of high-voltage electrical appliances in related technologies. The sum of the power required by the high-voltage accessories and the power required by the electric drive system is the battery discharge power.

[0067] By acquiring the electronic throttle signal, the maximum allowable discharge power of the high-voltage battery, the required power of high-voltage accessories (AC, PTC, DC-DC, etc.), the maximum output torque and efficiency of the electric drive system, the requested torque of the electric drive system under the current operating conditions is calculated, and this requested torque is executed.

[0068] In the electric drive system, after the requested torque is executed, the actual power consumed by the electric drive system is calculated as P1 = U*I by obtaining the DC bus terminal voltage U and current I of the electric drive system; the sum of the power of the high voltage accessories is P2, and the actual battery discharge power is calculated as P0 = P1 + P2.

[0069] The actual discharge power of the battery is compared with the maximum allowable discharge power of the battery. If the actual discharge power P0 is less than or equal to the maximum allowable discharge power of the battery, the previous power allocation is maintained. If the actual discharge power P0 is greater than the maximum allowable discharge power of the battery, the power of AC and PTC in the high-voltage accessory electrical appliances is reduced, while the power of DC-DC remains unchanged. At this time, the sum of the power of the new high-voltage accessory electrical appliances is P2, and the actual discharge power of the battery is P0 = P1 + P2.

[0070] The actual discharge power of the new battery is compared with the maximum allowable discharge power of the battery. If the actual discharge power P0 is less than or equal to the maximum allowable discharge power of the battery, the power distribution is maintained. If the actual discharge power P0 is greater than the maximum allowable discharge power of the battery, the power of AC and PTC in the high-voltage accessory is reduced to zero, while the power of DC-DC remains unchanged. At this time, the sum of the power of the new high-voltage accessory is P2, and the actual discharge power of the battery is P0 = P1 + P2.

[0071] The actual discharge power of the new battery at this time is compared with the maximum allowable discharge power of the battery. If the actual discharge power P0 of the battery is less than or equal to the maximum allowable discharge power of the battery, the power distribution is maintained. If the actual discharge power P0 of the battery is greater than the maximum allowable discharge power of the battery, the power of AC and PTC in the high-voltage accessory electrical appliances is reduced to zero, and the power of DC-DC is reduced to the minimum value that meets the low-voltage load voltage requirements of the whole vehicle. At this time, the sum of the power of the new high-voltage accessory electrical appliances is P2, and the actual discharge power of the battery at this time is P0 = P1 + P2.

[0072] The actual discharge power of the new battery at this time is compared with the maximum allowable discharge power of the battery. If the actual discharge power P0 of the battery is less than or equal to the maximum allowable discharge power of the battery, the power allocation is maintained. If the actual discharge power P0 of the battery is greater than the maximum allowable discharge power of the battery, a high-voltage battery fault is reported, and the maximum discharge power of the battery is reduced to the calibrated value.

[0073] This method compensates for battery overcharging caused by the actual efficiency of the electric drive system being lower than the rated value by reducing the power values ​​of other electrical components (ACP, PTC, DC-DC, etc.) in the high-voltage circuit. However, it has the following problems: 1. If the vehicle's ACP or PTC is not working at this time, it is impossible to optimize the torque distribution strategy by reducing its power, or the effect is minimal. Moreover, reducing the AC and PTC power or even reducing it to zero will cause user complaints; 2. It only considers the over-discharge problem of the high-voltage battery in electric mode. The overcharging problem of the high-voltage battery under energy recovery conditions caused by the efficiency difference of the electric drive system still needs to be solved.

[0074] Specifically, Figure 2 This is a schematic flowchart of a torque control method provided in an embodiment of this application.

[0075] like Figure 2 As shown, the torque control method includes the following steps:

[0076] In step S101, the current voltage of the high-voltage battery and the current temperature of the motor stator are obtained.

[0077] In step S102, the current temperature of the motor rotor is calculated based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor. Using the current voltage and the current temperature of the motor rotor as indexes, the efficiency table of the electric drive system corresponding to the current voltage and current temperature is queried, and the current efficiency of the electric drive system is determined based on the efficiency table.

[0078] The voltage and temperature of the high-voltage battery correspond to the efficiency table of the electric drive system; that is, different voltages and temperatures correspond to different efficiency tables of the electric drive system.

[0079] It is understood that, in the embodiments of this application, the current temperature of the motor rotor can be calculated based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor, and further, the current voltage of the high-voltage battery and the current temperature of the motor rotor can be used as an index to query the efficiency table of the corresponding electric drive system, and the current efficiency of the electric drive system can be determined based on the efficiency table.

[0080] In this embodiment of the application, the calculation of the current temperature of the motor rotor based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor further includes: obtaining the initial temperature, speed and torque of the motor rotor and the temperature of the motor windings, and calculating the losses of the motor rotor based on the speed and torque of the motor rotor; inputting the current temperature of the motor stator, the initial temperature of the motor rotor, the temperature of the motor windings and the losses of the motor rotor into the equivalent thermal network model, and the equivalent thermal network model outputting the current temperature of the motor rotor.

[0081] By considering the heat transfer and heat generation mechanism of the motor stator and rotor, the embodiments of this application can use the equivalent thermal network model of the motor rotor to output the current temperature of the motor rotor. The steps are as follows: calculate the loss of the motor rotor based on the rotational speed and torque of the motor rotor, input the obtained current temperature of the motor stator, the initial temperature of the motor rotor, the temperature of the motor windings, and the calculated loss of the motor rotor into the equivalent thermal network model, and output the current temperature of the motor rotor.

[0082] The specific steps to obtain the current temperature Kr of the motor rotor are as follows:

[0083] 1. By considering the heat transfer and heat generation mechanism of the motor stator and rotor, an equivalent thermal network model of the motor rotor is established with the motor rotor as the research object, as shown in the following formula. The power loss of the motor rotor is taken as the heat source of the rotor temperature rise, and the motor stator temperature is considered as a constant temperature heat source. The stator and rotor exchange heat through the air in the air gap.

[0084] C×dKr / dt=Pf-(Kr0-Ks) / R,

[0085] Where C represents the equivalent heat capacity of the rotor, Kr represents the rotor temperature, Kr0 represents the initial rotor temperature, Ks represents the motor winding temperature, Pf represents the power loss of the rotor section, and R represents the equivalent resistance of the motor rotor and stator exchanging heat through the air gap.

[0086] 2. The rotor loss power Pf of the motor can be calculated using the following formula. The motor loss power can be obtained by consulting the motor efficiency MAP chart based on the motor's operating speed and torque, thus calculating the efficiency at the current operating point. The motor loss power mainly consists of stator winding copper losses and silicon steel sheet iron losses. Stator losses are primarily copper losses, while rotor losses are primarily iron losses. The total motor loss minus the motor copper loss is considered as the heat generation power in the rotor thermal model. The motor copper loss is estimated using the motor operating current and the equivalent resistance of the windings.

[0087] Pf = P_mot_loss - Pcu,

[0088] Pcu = I² × Rs,

[0089] Where P_mot_loss represents the total power loss of the motor, Pcu represents the copper power loss of the motor windings, I represents the stator operating current of the motor, and Rs represents the resistance value of the three-phase windings of the motor.

[0090] In this embodiment of the application, determining the current efficiency of the electric drive system according to the efficiency table includes: obtaining the current speed and current torque of the motor; and querying the efficiency table using the current speed and current torque as indexes to obtain the current efficiency of the electric drive system.

[0091] The efficiency table stores the relationship between motor speed and torque and the efficiency of the electric drive system.

[0092] It is understood that, in the embodiments of this application, the current efficiency of the electric drive system can be obtained by querying the efficiency table based on the current speed and current torque of the motor, with each speed as the horizontal axis, torque as the vertical axis, and efficiency as the vertical axis.

[0093] In this embodiment of the application, before querying the efficiency table of the electric drive system corresponding to the current voltage and current temperature, the method further includes: dividing the voltage range of the high-voltage battery into multiple voltages at equal intervals; dividing the temperature range of the motor rotor into multiple temperature intervals; calibrating the efficiency of the electric drive system under different voltages and different temperature intervals according to the multiple voltages and multiple temperature intervals, and obtaining efficiency tables under different temperature intervals and different voltages.

[0094] The voltage range of the high-voltage battery can be represented as U0-Un, and the operating temperature range of the motor rotor can be represented as K0℃~Kn℃, where K0 is the lowest operating temperature of the motor rotor and Kn is the highest operating temperature of the motor rotor.

[0095] It is understood that the embodiments of this application can divide the DC voltage range of the high-voltage battery U0-Un into multiple temperature ranges at equal intervals. The voltage range includes at least the lowest, highest and rated operating voltage points. At the same time, under each voltage, multiple temperature ranges are further divided at equal intervals based on the motor rotor operating temperature range [K0, Kn]. For example, the interval is K, dividing it into several adjacent temperature ranges [K0, K1], [K2, K3]...[Kn-1, Kn]. Furthermore, the efficiency of the electric drive system under different voltages and different temperature ranges is calibrated based on multiple voltages and multiple temperature ranges to obtain efficiency tables for different temperature ranges and different voltages.

[0096] It should be noted that a wireless temperature sensor can be installed on the motor rotor. During the calibration process, the DC bus voltage and motor rotor temperature can be controlled as needed to obtain efficiency tables for different temperature ranges and different voltages.

[0097] In this embodiment of the application, the efficiency of the electric drive system under different voltages and temperature ranges is calibrated according to multiple voltages and multiple temperature ranges, including: performing drive and power generation efficiency tests on the electric drive system under each temperature range and each voltage; collecting the speed and torque of the drive system during the test process, calculating the efficiency corresponding to each speed and torque based on voltage, current, speed and torque; and generating an efficiency table of the electric drive system based on each speed, each torque and the corresponding efficiency.

[0098] It is understood that the embodiments of this application can test the driving and power generation efficiency of the electric drive system for each divided temperature range under each voltage, and obtain the efficiency table for different temperature ranges under this voltage. Further tests are conducted on the efficiency table under different voltages, taking into account the motor rotor temperature range, so as to obtain multiple efficiency tables for different combinations of voltages and different motor rotor temperature ranges. The speed and torque are collected during the test, and the efficiency corresponding to each speed and torque is calculated based on voltage, current, speed and torque. An efficiency table of the electric drive system is generated based on each speed, each torque and the corresponding efficiency.

[0099] Specifically, the efficiency calculation formula is as follows:

[0100]

[0101]

[0102] Where Eff1 is the driving efficiency of the motor system, Eff2 is the power generation efficiency of the motor system, Tout is the mechanical torque output by the motor in Nm, Nout is the output speed of the motor system in r / min, Uin is the voltage input to the motor system from the DC bus in V, and Iin is the current input to the motor system from the DC bus in A.

[0103] Based on the above formula, calculate the efficiency at each operating point, and plot a three-dimensional graph with each speed as the horizontal axis, torque as the vertical axis, and efficiency as the vertical axis. This will yield the efficiency table of the electric drive system for a certain voltage and motor rotor temperature range.

[0104] In step S103, the electric drive request torque of the electric drive system is calculated based on the current efficiency, and the electric drive system is controlled to execute the electric drive request torque to provide power to the vehicle or to achieve energy recovery.

[0105] It is understood that, according to the embodiments of this application, the electric drive system can calculate the electric drive requested torque based on the current efficiency, and control the electric drive system to execute the electric drive requested torque in order to provide power to the whole vehicle or realize energy recovery.

[0106] In this embodiment of the application, calculating the electric drive requested torque of the electric drive system based on the current efficiency includes: obtaining the allowable power of the electric drive system and the vehicle's required torque; calculating the allowable torque of the electric drive system based on the current efficiency and allowable power; and determining the electric drive requested torque based on the allowable torque, the vehicle's required torque, and the maximum torque of the electric drive system.

[0107] Among them, the required torque of the whole vehicle can be obtained by analyzing the accelerator pedal opening signal; the allowable torque of the electric drive system is calculated based on the current efficiency and allowable power; the maximum torque of the electric drive system can be obtained based on the capability feedback of the electric drive system; the allowable torque includes the allowable driving torque and the allowable generating torque; the required torque of the whole vehicle includes the required torque of the whole vehicle power and the required torque of the whole vehicle braking; the maximum torque includes the maximum output torque of the electric drive and the maximum generating torque of the electric drive.

[0108] The specific formula for calculating the permissible torque of an electric drive system is as follows:

[0109] T1=9550×P×η×0.377×r / V,

[0110] Where T1 is the allowable torque of the electric drive system, P is the allowable power of the electric drive system, η is the current efficiency of the electric drive system as found in the efficiency table corresponding to this rotor temperature range, r is the tire radius, and V is the vehicle speed.

[0111] After calculating the permissible torque of the electric drive system, the vehicle controller can further determine the electric drive requested torque based on the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system.

[0112] In this embodiment of the application, obtaining the permissible power of the electric drive system includes: obtaining the maximum permissible discharge power of the high-voltage battery and the power of the high-voltage accessory; and calculating the permissible power of the electric drive system based on the maximum permissible discharge power and the power of the high-voltage accessory.

[0113] The vehicle controller can obtain the maximum allowable discharge power of the high-voltage battery and the power of the high-voltage accessories, including DC-DC converters, electric heating modules, air conditioning compressors and other electrical appliances.

[0114] It is understood that, in the embodiments of this application, the allowable power of the electric drive system can be calculated based on the maximum allowable discharge power of the high-voltage battery and the power of the high-voltage accessories. The calculation formula is as follows:

[0115] P = Pa - (P1 + P2 + P3 + P4),

[0116] Where P is the allowable power of the electric drive system, Pa is the maximum allowable discharge power of the battery, P1 is the power of the DC-DC converter, P2 is the power of the electric heating module, P3 is the power of the air conditioning compressor, and P4 is the power of other electrical appliances.

[0117] In this embodiment of the application, determining the electric drive requested torque based on the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system includes: if the vehicle is in electric operating condition, the minimum value among the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system is taken as the electric drive requested torque; if the vehicle is in energy recovery operating condition, the maximum value among the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system is taken as the electric drive requested torque.

[0118] It is understood that, according to the operating conditions of the vehicle, the electric drive requested torque can be further determined based on the allowable torque, the vehicle's required torque, and the maximum torque of the electric drive system. When the vehicle is in electric operating condition, the minimum value among the allowable torque, the vehicle's required torque, and the maximum torque of the electric drive system is used as the electric drive requested torque. If the vehicle is in energy recovery operating condition, the maximum value among the allowable torque, the vehicle's required torque, and the maximum torque of the electric drive system is used as the electric drive requested torque.

[0119] When the vehicle is in electric driving mode, the electric drive requests torque Tm:

[0120] Tm = min(T1, T2, T3),

[0121] Where T1 is the allowable torque of the electric drive system, T2 is the required torque of the whole vehicle, and T3 is the maximum torque of the electric drive system.

[0122] When the vehicle is in energy recovery mode, the electric drive requests torque Tm:

[0123] Tm = max(T1, T2, T3),

[0124] Where T1 is the allowable torque of the electric drive system, T2 is the required torque of the whole vehicle, and T3 is the maximum torque of the electric drive system.

[0125] In this embodiment of the application, controlling the electric drive system to execute the electric drive requested torque includes: if the electric drive requested torque is an allowable torque, controlling the electric drive system to execute the electric drive requested torque based on the difference between the actual power of the electric drive system and the allowable power; if the electric drive requested torque is the vehicle's required torque or the maximum torque of the electric drive system, then controlling the electric drive system to execute the electric drive requested torque.

[0126] It is understood that, in the embodiments of this application, when the electric drive requested torque is the allowable torque, the electric drive system can be controlled to execute the electric drive requested torque based on the difference between the actual power and the allowable power of the electric drive system. The specific control method is described in the following embodiments and will not be repeated here. When the electric drive requested torque is the required torque of the whole vehicle or the maximum torque of the electric drive system, the electric drive system is controlled to execute the electric drive requested torque.

[0127] In this embodiment, controlling the electric drive system to execute the requested electric drive torque based on the difference between the actual power and the allowable power of the electric drive system includes: if the difference is a preset value, then executing the requested electric drive torque; if the difference is greater than the preset value, then determining a first efficiency of the electric drive system based on the efficiency table corresponding to the next temperature range of the current voltage and current temperature, and redetermining the requested electric drive torque based on the first efficiency; if the difference is less than the preset value, then determining a second efficiency of the electric drive system based on the efficiency table corresponding to the previous temperature range of the current voltage and current temperature, and redetermining the requested electric drive torque based on the second efficiency.

[0128] The preset value can be set to 0, etc.

[0129] It is understood that in this embodiment, the difference between the actual power and the allowable power of the electric drive system is calculated. If the difference is a preset value, the requested torque continues to be executed. If the difference is greater than the preset value, the first efficiency is queried from the efficiency table corresponding to the next temperature range higher than the current voltage and current temperature, and the electric drive requested torque is re-determined based on the first efficiency. If the difference is less than the preset value, the second efficiency is queried from the efficiency table corresponding to the previous temperature range lower than the current voltage and current temperature, and the electric drive requested torque is re-determined based on the second efficiency. The formula for re-determining the electric drive requested torque is as follows:

[0130] T1ˊ=9550×P×ηˊ×0.377×r / V,

[0131] Where T1ˊ is the allowable torque of the electric drive system, P is the allowable power of the electric drive system, ηˊ is the efficiency of the electric drive system (first efficiency) found in the efficiency table corresponding to the next temperature range adjacent to this motor rotor temperature range, or the efficiency of the electric drive system (second efficiency) found in the efficiency table corresponding to the previous temperature range adjacent to this motor rotor temperature range, r is the tire radius, and V is the vehicle speed.

[0132] Furthermore, after calculating the electric drive requested torque, the vehicle controller compares the allowable torque of the electric drive system with the vehicle's required torque obtained from the accelerator pedal opening signal and the maximum torque of the electric drive system, and takes the minimum value as the electric drive requested torque.

[0133] Tmˊ=min(T1ˊ,T2,T3,

[0134] Where T1ˊ is the allowable torque of the electric drive system recalculated according to the efficiency table of the next temperature range, T2 is the torque required by the whole vehicle, and T3 is the maximum torque of the electric drive system.

[0135] To request torque Tmˊ for the electric drive, the actual power consumed by the electric drive system is obtained and the difference is calculated with the allowable power of the electric drive system. If the difference is zero, the request torque is continued. If the difference is greater than zero, the efficiency value is looked up in the efficiency table corresponding to the next temperature range adjacent to the current temperature range. If the difference is less than zero, the efficiency value is looked up in the efficiency table corresponding to the previous temperature range adjacent to the current temperature range, and the above steps are repeated to obtain the electric drive request torque again.

[0136] In this embodiment of the application, the method further includes: if the efficiency table is the efficiency table corresponding to the highest temperature range, then the electric drive requested torque is adjusted according to the portion of the actual power exceeding the allowable power; if the efficiency table is the efficiency table corresponding to the lowest temperature range, then the electric drive requested torque is adjusted according to the portion of the actual power lower than the allowable power.

[0137] Understandably, if the efficiency of the electric drive system has been looked up to the efficiency table corresponding to the highest operating temperature range, and it still exceeds or falls below the allowable power of the electric drive system, this application embodiment can correct the requested torque of the electric drive. When the actual power exceeds the allowable power, the power of the electric drive system is limited; when the actual power is below the allowable power, the power of the electric drive system is increased. Specifically, the torque difference between the actual power consumption exceeding the maximum allowable discharge power of the battery and the current motor speed is calculated according to the following formula, and the requested torque is corrected accordingly:

[0138] Tj=Tm-9550×(P+Pq-Pa)×η×0.377×r / V,

[0139] Where Tj is the requested torque of the electric drive, Tm is the requested torque value at the previous moment, P is the actual power consumed by the electric drive system at the previous moment, Pq is the sum of the power of the DC converter, electric heating module, air conditioning compressor and other high-voltage electrical appliances at the previous moment, Pa is the maximum allowable discharge power of the battery at the previous moment, η is the efficiency value corresponding to the highest temperature range under the current voltage, r is the tire radius, and V is the vehicle speed.

[0140] The torque control method of this application will be illustrated below through a specific embodiment.

[0141] First, the method for obtaining the efficiency table of an electric drive system is explained.

[0142] Step 1: Divide the DC voltage range of the high-voltage battery, U0-Un, into multiple voltage points at equal intervals. Considering the battery's operating voltage, the voltage range should include at least the lowest, highest, and rated operating voltage points.

[0143] Step 2: The operating temperature range of the motor rotor is K0℃~Kn℃, where K0 is the lowest operating temperature of the motor rotor and Kn is the highest operating temperature of the motor rotor. The operating temperature range [K0, Kn] is divided into several adjacent temperature ranges [K0, K1], [K2, K3]...[Kn-1, Kn] by temperature interval k.

[0144] Step 3: After the motor system test bench is completed, a wireless temperature sensor is installed on the motor rotor to test the drive and power generation efficiency under different voltages and rotor temperatures.

[0145] Step 4: Power Analyzer Setup: Measure the voltage and current at the electric drive input. Set the analog battery voltage to the required voltage value U0.

[0146] Step 5: Control the motor to preheat according to the previous operating condition, with the motor rotor temperature within the range of [K0, K1]. Set the test operating points according to Table 1. For each operating point, ensure that the initial motor temperature remains within the range of [K0, K1]. If the temperature exceeds the range, stop the machine for cooling or run it according to the previous operating condition until the temperature is within the range. Run each operating point continuously for 5 seconds. Record the bench data throughout the test. The bench system recording frequency is 10Hz. Table 1 shows the efficiency test operating points.

[0147] Table 1

[0148]

[0149] Step 6: Efficiency Calculation. Calculate the efficiency under different operating conditions. The calculation formula is as follows:

[0150]

[0151]

[0152] Where Eff1 is the driving efficiency of the motor system, Eff2 is the power generation efficiency of the motor system, Tout is the mechanical torque output by the motor in Nm, Nout is the output speed of the motor system in r / min, Uin is the voltage input to the motor system from the DC bus in V, and Iin is the current input to the motor system from the DC bus in A.

[0153] Based on the above formula, calculate the efficiency at each operating point, then use each speed as the horizontal axis, torque as the vertical axis, and efficiency as the vertical axis to draw a three-dimensional graph, thus obtaining the efficiency table for a certain voltage and motor rotor temperature range.

[0154] Step 7: Repeat steps 4 to 6 to obtain the efficiency table of the electric drive system with different combinations of voltage and rotor temperature ranges.

[0155] Step 8: Estimate the rotor temperature Kr.

[0156] 1. By considering the heat transfer and heat generation mechanism of the motor stator and rotor, an equivalent thermal network model of the motor rotor is established with the motor rotor as the research object, as shown in the following formula. The power loss of the motor rotor is taken as the heat source of the rotor temperature rise, and the motor stator temperature is considered as a constant temperature heat source. The stator and rotor exchange heat through the air in the air gap.

[0157] C×dKr / dt=Pf-(Kr0-Ks) / R,

[0158] Where C represents the equivalent heat capacity of the rotor, Kr represents the rotor temperature, Kr0 represents the initial rotor temperature, Ks represents the motor winding temperature, Pf represents the power loss of the rotor section, and R represents the equivalent resistance of the motor rotor and stator through the air gap for heat exchange.

[0159] 2. The rotor loss power Pf of the motor can be calculated using the following formula. The motor loss power can be obtained by consulting the motor efficiency MAP chart based on the motor's operating speed and torque, thus calculating the efficiency at the current operating point. The motor loss power mainly consists of stator winding copper losses and silicon steel sheet iron losses. Stator losses are primarily copper losses, while rotor losses are primarily iron losses. The total motor loss minus the motor copper loss is considered as the heat generation power in the rotor thermal model. The motor copper loss is estimated using the motor operating current and the equivalent winding resistance.

[0160] Pf = P_mot_loss - Pcu,

[0161] Pcu=I 2 ×Rs,

[0162] Where P_mot_loss represents the total power loss of the motor, Pcu represents the copper power loss of the motor windings, I represents the stator operating current of the motor, and Rs represents the resistance value of the three-phase windings of the motor.

[0163] 3. The initial rotor temperature value Tr0 in the equivalent thermal network model of the motor rotor will affect the accuracy of the motor rotor temperature estimation. Consideration should be given to using electric drive bench experiments to determine the time required for the motor to naturally cool from different rotor temperatures to room temperature and the temperature change curves during this process. Figure 3 As shown, each time the motor stops or is powered off, the estimated rotor temperature value Kr1 is recorded. Based on the rotor temperature and the duration of the shutdown, the motor rotor temperature cooling curve is queried to determine the rotor's initial temperature when the motor restarts. Tr0 in the equivalent thermal network model is then replaced. The motor winding temperature is collected in real time using a temperature sensor.

[0164] 4. The equivalent heat capacity C of the motor rotor and the equivalent heat transfer resistance R of the stator and rotor need to be identified through parameter identification using motor system bench test data to obtain a thermal network model for estimating the motor rotor temperature. The motor rotor temperature can be estimated in real time using the acquired motor winding temperature signal, motor rotor initial temperature, motor operating current, speed, and torque signals.

[0165] The following describes the torque control methods for vehicles under different operating conditions:

[0166] I. Torque Control Methods for Vehicles under Electric Operating Conditions

[0167] 1. For example Figure 4 As shown, the vehicle controller calculates the allowable power of the electric drive system by acquiring the maximum allowable discharge power of the battery, the power of the DC-DC converter, the power of the electric heating module, the power of the air conditioning compressor, and the power of other electrical appliances, according to the following formula:

[0168] P = Pa - (P1 + P2 + P3 + P4),

[0169] Where P is the allowable power of the electric drive system, Pa is the maximum allowable discharge power of the battery, P1 is the power of the DC-DC converter, P2 is the power of the electric heating module, P3 is the power of the air conditioning compressor, and P4 is the power of other electrical appliances.

[0170] 2. Based on the current battery voltage and the estimated rotor temperature, determine the drive efficiency table to be queried at the current moment through logical judgment.

[0171] 3. By acquiring vehicle speed and electric drive torque signals, and consulting the efficiency table, calculate the allowable torque of the electric drive system according to the following formula.

[0172] T1=9550×P×η×0.377×r / V,

[0173] Where T1 is the allowable torque of the electric drive system, P is the allowable power of the electric drive system, η is the current efficiency of the electric drive system as found in the efficiency table corresponding to this rotor temperature range, r is the tire radius, and V is the vehicle speed.

[0174] 4. The vehicle controller calculates the electric drive requested torque by combining the maximum torque of the integrated electric drive system, the torque required by the vehicle's power, and the previously calculated allowable torque of the electric drive system.

[0175] Tm = min(T1, T2, T3),

[0176] Where T1 is the allowable torque of the electric drive system, T2 is the torque required for the vehicle's power, and T3 is the maximum torque of the electric drive system.

[0177] 5. For example Figure 5As shown, when the electric drive requests torque Tm = T1, the actual power consumed by the electric drive system is obtained and the difference is calculated with the allowable power of the electric drive system. If the difference is zero, the request torque continues. If the difference is greater than zero, the efficiency value is looked up in the efficiency table corresponding to the next temperature range adjacent to the current temperature range. If the difference is less than zero, the efficiency value is looked up in the efficiency table corresponding to the previous temperature range adjacent to the current temperature range, and the electric drive requests torque is calculated according to the following formula:

[0178] T1ˊ=9550×P×ηˊ×0.377×r / V,

[0179] Where T1ˊ is the allowable torque of the electric drive system, P is the allowable power of the electric drive system, ηˊ is the efficiency of the electric drive system found in the efficiency table for the next temperature range adjacent to this motor rotor temperature range, r is the tire radius, and V is the vehicle speed.

[0180] 6. The vehicle controller compares the allowable torque of the electric drive system with the vehicle's required torque obtained from the accelerator pedal opening signal and the maximum torque of the electric drive system, and takes the minimum value as the requested torque for the electric drive system.

[0181] Tmˊ=min(T1ˊ,T2,T3,

[0182] Where T1ˊ is the allowable torque of the electric drive system recalculated according to the efficiency table of the next temperature range, T2 is the torque required by the whole vehicle, and T3 is the maximum torque of the electric drive system.

[0183] 7. Execute the electric drive request torque Tmˊ. Obtain the actual power consumption of the electric drive system and calculate the difference between it and the allowable power of the electric drive system. If the difference is zero, continue to execute this request torque. If the difference is greater than zero, look up the efficiency value according to the efficiency table corresponding to the next temperature range adjacent to the current temperature range. If the difference is less than zero, look up the efficiency value according to the efficiency table corresponding to the previous temperature range adjacent to the current temperature range, and repeat steps 5 and 6 above.

[0184] 8. If the motor drive efficiency has been looked up to the efficiency table corresponding to the highest operating temperature range and still exceeds the allowable power of the electric drive system, then the drive power of the electric drive system will be limited; if the motor drive efficiency has been looked up to the efficiency table corresponding to the lowest operating temperature range and still is lower than the allowable power of the electric drive system, then the drive power of the electric drive system will be increased; the torque difference between the actual power consumption exceeding the maximum allowable discharge power of the battery and the current motor speed will be calculated using the following formula, and a torque correction request will be made:

[0185] Tj=Tm-9550×(P+Pq-Pa)×η×0.377×r / V,

[0186] Where Tj is the torque request value of the electric drive system, Tm is the torque request value at the previous moment, P is the actual power consumed by the electric drive system at the previous moment, Pq is the sum of the power of the DC converter, electric heating module, air conditioning compressor and other high-voltage electrical appliances at the previous moment, Pa is the maximum allowable discharge power of the battery at the previous moment, η is the efficiency value corresponding to the highest temperature range under the current voltage, r is the tire radius, and V is the vehicle speed.

[0187] When the requested torque Tm = T2 or Tm = T3 of the electric drive system is executed, the requested torque continues to be executed.

[0188] II. Torque Control Methods for Vehicles Under Energy Recovery Conditions

[0189] 1. For example Figure 6 As shown, the vehicle controller obtains the battery's allowable charging power, DC-DC converter power, electric heating module power, air conditioning compressor power, and other electrical appliance power, and calculates the allowable power generation of the electric drive system according to the following formula:

[0190] P = -(Pa + P1 + P2 + P3 + P4),

[0191] Where P is the allowable power of the electric drive system, Pa is the maximum allowable discharge power of the battery, P1 is the power of the DC-DC converter, P2 is the power of the electric heating module, P3 is the power of the air conditioning compressor, and P4 is the power of other electrical appliances.

[0192] 2. Based on the current battery voltage and motor rotor temperature signals, determine the current recycling efficiency table through logical judgment.

[0193] 3. By acquiring vehicle speed signals and motor rotor temperature signals, and querying the recycling efficiency map table, the allowable generator torque of the electric drive system is calculated according to the following formula:

[0194] T1=9550×P×0.377×r / (V×η),

[0195] Where T1 is the allowable generating torque of the electric drive system, P is the allowable generating power of the electric drive system, η is the generating efficiency of the electric drive system found in the efficiency table corresponding to this rotor magnet temperature range, r is the tire radius, and V is the vehicle speed.

[0196] 4. The vehicle controller calculates the requested torque of the electric drive system by combining the maximum generating torque of the integrated electric drive system, the braking torque required by the vehicle, and the previously calculated allowable generating torque of the electric drive system.

[0197] Tm = max(T1, T2, T3),

[0198] Where T1 is the allowable generating torque of the electric drive system, T2 is the braking torque required by the vehicle, and T3 is the maximum generating torque of the electric drive system.

[0199] 5. For example Figure 7 As shown, when the requested torque Tm = T1 of the electric drive system is executed, the actual power generated by the electric drive system is obtained and the difference between it and the allowable power generated by the electric drive system is calculated. If the difference is zero, the requested torque is executed. If the difference is less than zero, the efficiency value is looked up in the efficiency table corresponding to the next temperature range adjacent to the current temperature range. If the difference is greater than zero, the efficiency value is looked up in the efficiency table corresponding to the previous temperature range adjacent to the current temperature range. The allowable torque generated by the electric drive system is then calculated according to the following formula:

[0200] T1ˊ=9550×P×0.377×r / (V×ηˊ),

[0201] Where T1ˊ is the allowable generating torque of the electric drive system, P is the allowable generating power of the electric drive system, ηˊ is the generating efficiency of the electric drive system found in the efficiency table for the next temperature range adjacent to this motor rotor temperature range, r is the tire radius, and V is the vehicle speed.

[0202] 6. The vehicle controller calculates the requested torque of the electric drive system by combining the maximum generating torque of the integrated electric drive system, the braking torque required by the vehicle, and the previously calculated allowable generating torque of the electric drive system.

[0203] Tmˊ=max(T1ˊ,T2,T3),

[0204] Where T1ˊ is the allowable torque of the electric drive system recalculated according to the efficiency table of the next temperature range, T2 is the braking torque required by the whole vehicle, and T3 is the maximum generating torque of the electric drive system.

[0205] 7. Execute the requested torque Tmˊ of the electric drive system. Obtain the actual power generation of the electric drive system and calculate the difference between it and the allowable power generation of the electric drive system. If the difference is zero, continue to execute the requested torque. If the difference is less than zero, look up the efficiency value according to the efficiency table of the next temperature range adjacent to the current temperature range. If the difference is greater than zero, look up the efficiency value according to the efficiency map table of the previous temperature range adjacent to the current temperature range, and repeat steps 5 and 6 above.

[0206] 8. If the power generation efficiency of the electric drive system has been looked up to the efficiency table corresponding to the highest operating temperature range, and still exceeds the maximum allowable power generation of the electric drive system, then the power generation of the electric drive system will be limited; if the efficiency of the electric drive system has been looked up to the efficiency table corresponding to the lowest operating temperature range, and still falls below the maximum allowable power generation of the electric drive system, then the power generation of the electric drive system will be increased; by calculating the difference between the actual power generation and the battery's maximum allowable charging power, and combining this with the current motor speed to calculate the torque difference, a torque correction request will be made.

[0207] Tj=Tm-9550×(P+Pq+Pa)×0.377×r / (V×η),

[0208] Where Tj is the torque request value of the electric drive system, Tm is the torque request value at the previous moment, P is the actual power generation of the electric drive system at the previous moment, Pq is the sum of the power of the DC converter, electric heating module, air conditioning compressor and other high-voltage electrical appliances at the previous moment, Pa is the maximum allowable charging power of the battery at the previous moment, η is the efficiency value corresponding to the highest temperature range under the current voltage, r is the tire radius, and V is the vehicle speed.

[0209] When the requested torque Tm = T2 or Tm = T3 of the electric drive system is executed, the requested torque continues to be executed.

[0210] According to the torque control method proposed in the embodiments of this application, the efficiency table corresponding to the electric drive system can be determined based on the current voltage of the high-voltage battery and the current temperature of the motor rotor, and the current efficiency of the electric drive system can be further determined. The influence of different battery voltages and different motor rotor temperatures on the efficiency of the electric drive system is taken into account, reducing the difference between the actual efficiency and the calibrated efficiency value of the electric drive system, and controlling the electric drive system to execute the electric drive request torque calculated based on the current efficiency, so as to provide power to the whole vehicle or realize energy recovery.

[0211] Next, the torque control device proposed according to the embodiments of this application is described with reference to the accompanying drawings.

[0212] Figure 8 This is a block diagram of a torque control device according to an embodiment of this application.

[0213] like Figure 8 As shown, the torque control device 10 includes: an acquisition module 100, a determination module 200, and a control module 300.

[0214] The acquisition module 100 is used to acquire the current voltage of the high-voltage battery and the current temperature of the motor stator; the determination module 200 is used to calculate the current temperature of the motor rotor based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor, and uses the current voltage and the current temperature of the motor rotor as indexes to query the efficiency table of the electric drive system corresponding to the current voltage and the current temperature, and determines the current efficiency of the electric drive system based on the efficiency table; the control module 300 is used to calculate the electric drive requested torque of the electric drive system based on the current efficiency, and control the electric drive system to execute the electric drive requested torque to provide power to the vehicle or realize energy recovery.

[0215] In this embodiment, the control module 300 is further configured to: obtain the allowable power of the electric drive system and the required torque of the vehicle; calculate the allowable torque of the electric drive system based on the current efficiency and allowable power; and determine the electric drive requested torque based on the allowable torque, the required torque of the vehicle, and the maximum torque of the electric drive system.

[0216] In this embodiment, the control module 300 is further configured to: obtain the maximum allowable discharge power of the high-voltage battery and the power of the high-voltage accessory; and calculate the allowable power of the electric drive system based on the maximum allowable discharge power and the power of the high-voltage accessory.

[0217] In this embodiment, the control module 300 is further configured to: if the vehicle is in electric operating condition, use the minimum value among the allowable torque, the vehicle required torque, and the maximum torque of the electric drive system as the electric drive requested torque; if the vehicle is in energy recovery operating condition, use the maximum value among the allowable torque, the vehicle required torque, and the maximum torque of the electric drive system as the electric drive requested torque.

[0218] In this embodiment, the control module 300 is further configured to: if the electric drive requested torque is the allowable torque, control the electric drive system to execute the electric drive requested torque based on the difference between the actual power and the allowable power of the electric drive system; if the electric drive requested torque is the vehicle's required torque or the maximum torque of the electric drive system, control the electric drive system to execute the electric drive requested torque.

[0219] In this embodiment, the control module 300 is further configured to: if the difference is a preset value, then execute the electric drive request torque; if the difference is greater than the preset value, then determine the first efficiency of the electric drive system according to the efficiency table corresponding to the next temperature range of the current voltage and current temperature, and redetermine the electric drive request torque according to the first efficiency; if the difference is less than the preset value, then determine the second efficiency of the electric drive system according to the efficiency table corresponding to the previous temperature range of the current voltage and current temperature, and redetermine the electric drive request torque according to the second efficiency.

[0220] In this embodiment of the application, the apparatus 10 further includes a correction module.

[0221] The correction module is used to correct the electric drive requested torque based on the portion of the actual power exceeding the allowable power if the efficiency table corresponds to the highest temperature range; and to correct the electric drive requested torque based on the portion of the actual power below the allowable power if the efficiency table corresponds to the lowest temperature range.

[0222] In this embodiment of the application, the determining module 200 is further configured to: obtain the current speed and current torque of the motor; and use the current speed and current torque as indexes to query the efficiency table to obtain the current efficiency of the electric drive system.

[0223] In this embodiment of the application, the device 10 further includes a calibration module.

[0224] The calibration module is used to divide the voltage range of the high-voltage battery into multiple voltages at equal intervals before querying the efficiency table of the electric drive system corresponding to the current voltage and temperature; divide the temperature range of the motor rotor into multiple temperature intervals; and calibrate the efficiency of the electric drive system under different voltages and temperature intervals based on the multiple voltages and multiple temperature intervals to obtain the efficiency table under different temperature intervals and different voltages.

[0225] In this embodiment, the calibration module is further configured to: perform drive and power generation efficiency tests on the electric drive system at each temperature range and at each voltage; collect the speed and torque during the drive system test process, calculate the efficiency corresponding to each speed and torque based on voltage, current, speed and torque; and generate an efficiency table of the electric drive system based on each speed, each torque and the corresponding efficiency.

[0226] In this embodiment of the application, the determining module 100 is further configured to: obtain the initial temperature, speed and torque of the motor rotor and the temperature of the motor windings, and calculate the loss of the motor rotor based on the speed and torque of the motor rotor; input the current temperature of the motor stator, the initial temperature of the motor rotor, the temperature of the motor windings and the loss of the motor rotor into the equivalent thermal network model, and the equivalent thermal network model outputs the current temperature of the motor rotor.

[0227] It should be noted that the foregoing explanation of the torque control method embodiment also applies to the torque control device of this embodiment, and will not be repeated here.

[0228] According to the torque control device proposed in the embodiments of this application, the efficiency table corresponding to the electric drive system can be determined based on the current voltage of the high-voltage battery and the current temperature of the motor rotor, and the current efficiency of the electric drive system can be further determined. The influence of different battery voltages and different motor rotor temperatures on the efficiency of the electric drive system is taken into account, reducing the difference between the actual efficiency and the calibrated efficiency value of the electric drive system, and controlling the electric drive system to execute the electric drive request torque calculated based on the current efficiency, so as to provide power to the whole vehicle or realize energy recovery.

[0229] like Figure 9 As shown in the figure, this application embodiment also provides a vehicle 20, including: an electric drive system 21 and a vehicle controller 22.

[0230] The vehicle controller 22 is used to obtain the current voltage of the high-voltage battery and the current temperature of the motor rotor. Using the current voltage and current temperature as indexes, it queries the efficiency table of the electric drive system corresponding to the current voltage and current temperature, determines the current efficiency of the electric drive system based on the efficiency table, calculates the electric drive requested torque of the electric drive system based on the current efficiency, and controls the electric drive system to execute the electric drive requested torque to provide power to the vehicle or realize energy recovery.

[0231] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the torque control method described above.

[0232] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0233] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0234] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0235] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (FPGAs), field-programmable gate arrays (FPGAs), etc.

[0236] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it includes one or a combination of the steps of the method embodiments.

[0237] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A torque control method, characterized in that, Includes the following steps: Obtain the current voltage of the high-voltage battery and the current temperature of the motor stator; The current temperature of the motor rotor is calculated based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor. Using the current voltage and the current temperature of the motor rotor as indexes, the efficiency table of the electric drive system corresponding to the current voltage and the current temperature is queried, and the current efficiency of the electric drive system is determined based on the efficiency table. Calculate the electric drive requested torque of the electric drive system based on the current efficiency, and control the electric drive system to execute the electric drive requested torque to provide power to the vehicle or to achieve energy recovery; The step of calculating the electric drive requested torque of the electric drive system based on the current efficiency includes: Obtain the allowable power of the electric drive system and the required torque of the vehicle; Calculate the permissible torque of the electric drive system based on the current efficiency and the permissible power. The electric drive requested torque is determined based on the permissible torque, the vehicle required torque, and the maximum torque of the electric drive system. Controlling the electric drive system to execute the requested electric drive torque based on the difference between the actual power of the electric drive system and the allowable power includes: If the difference is a preset value, then the electric drive torque request is executed; If the difference is greater than the preset value, the first efficiency of the electric drive system is determined according to the efficiency table corresponding to the next temperature range of the current voltage and the current temperature, and the electric drive requested torque is re-determined according to the first efficiency. If the difference is less than the preset value, the second efficiency of the electric drive system is determined according to the efficiency table corresponding to the previous temperature range of the current voltage and the current temperature, and the electric drive requested torque is re-determined according to the second efficiency.

2. The torque control method according to claim 1, characterized in that, The step of obtaining the allowable power of the electric drive system includes: Obtain the maximum allowable discharge power of the high-voltage battery and the power of the high-voltage accessory; The permissible power of the electric drive system is calculated based on the maximum permissible discharge power and the power of the high-voltage accessory.

3. The torque control method according to claim 1, characterized in that, Determining the electric drive requested torque based on the permissible torque, the vehicle's required torque, and the maximum torque of the electric drive system includes: If the vehicle is in electric mode, the minimum value among the allowable torque, the required torque of the whole vehicle, and the maximum torque of the electric drive system shall be used as the electric drive requested torque. If the vehicle is in energy recovery mode, the maximum value among the allowable torque, the required torque of the whole vehicle, and the maximum torque of the electric drive system shall be used as the electric drive requested torque.

4. The torque control method according to claim 1, characterized in that, The control of the electric drive system to execute the requested electric drive torque includes: If the requested electric drive torque is the allowable torque, the electric drive system is controlled to execute the requested electric drive torque based on the difference between the actual power of the electric drive system and the allowable power. If the requested electric drive torque is the required torque of the vehicle or the maximum torque of the electric drive system, then the electric drive system is controlled to execute the requested electric drive torque.

5. The torque control method according to claim 1, characterized in that, Also includes: If the efficiency table is the efficiency table corresponding to the highest temperature range, then the electric drive requested torque is adjusted according to the portion of the actual power that exceeds the allowable power; If the efficiency table is the efficiency table corresponding to the lowest temperature range, then the electric drive requested torque is adjusted according to the portion of the actual power that is lower than the allowable power.

6. The torque control method according to claim 1, characterized in that, Determining the current efficiency of the electric drive system based on the efficiency table includes: Obtain the current speed and current torque of the motor; Using the current speed and the current torque as indexes, the current efficiency of the electric drive system is obtained by querying the efficiency table.

7. The torque control method according to claim 1, characterized in that, Before querying the efficiency table of the electric drive system corresponding to the current voltage and the current temperature, the process also includes: The voltage range of the high-voltage battery is divided into multiple voltages at equal intervals; The temperature range of the motor rotor is divided into multiple temperature zones; The efficiency of the electric drive system under different voltages and temperature ranges is calibrated based on the multiple voltages and multiple temperature ranges, resulting in an efficiency table for different temperature ranges and different voltages.

8. The torque control method according to claim 7, characterized in that, The step of calibrating the efficiency of the electric drive system under different voltages and different temperature ranges based on the plurality of voltages and the plurality of temperature ranges includes: The drive and power generation efficiency of the electric drive system were tested in each temperature range and at each voltage. The speed and torque of the drive system during the test are collected, and the efficiency corresponding to each speed and torque is calculated based on the voltage, current, speed and torque. An efficiency table for the electric drive system is generated based on each rotational speed, each torque, and the corresponding efficiency.

9. The torque control method according to claim 1, characterized in that, The step of calculating the current temperature of the motor rotor based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor also includes: The initial temperature, speed, and torque of the motor rotor, as well as the temperature of the motor windings, are obtained, and the losses of the motor rotor are calculated based on the speed and torque of the motor rotor. The current temperature of the motor stator, the initial temperature of the motor rotor, the temperature of the motor windings, and the losses of the motor rotor are input into the equivalent thermal network model, and the equivalent thermal network model outputs the current temperature of the motor rotor.

10. A torque control device, characterized in that, include: The acquisition module is used to acquire the current voltage of the high-voltage battery and the current temperature of the motor stator; The determination module is used to calculate the current temperature of the motor rotor based on the current temperature of the motor stator and the equivalent thermal network model of the motor rotor, and to query the efficiency table of the electric drive system corresponding to the current voltage and the current temperature of the motor rotor as indexes, and determine the current efficiency of the electric drive system based on the efficiency table. The control module is used to calculate the electric drive requested torque of the electric drive system based on the current efficiency, and control the electric drive system to execute the electric drive requested torque to provide power to the vehicle or realize energy recovery. The step of calculating the electric drive requested torque of the electric drive system based on the current efficiency includes: Obtain the allowable power of the electric drive system and the required torque of the vehicle; Calculate the permissible torque of the electric drive system based on the current efficiency and the permissible power. The electric drive requested torque is determined based on the permissible torque, the vehicle required torque, and the maximum torque of the electric drive system. Controlling the electric drive system to execute the requested electric drive torque based on the difference between the actual power of the electric drive system and the allowable power includes: If the difference is a preset value, then the electric drive torque request is executed; If the difference is greater than the preset value, the first efficiency of the electric drive system is determined according to the efficiency table corresponding to the next temperature range of the current voltage and the current temperature, and the electric drive requested torque is re-determined according to the first efficiency. If the difference is less than the preset value, the second efficiency of the electric drive system is determined according to the efficiency table corresponding to the previous temperature range of the current voltage and the current temperature, and the electric drive requested torque is re-determined according to the second efficiency.

11. A vehicle, characterized in that, include: Electric drive system; The vehicle controller is used to obtain the current voltage of the high-voltage battery and the current temperature of the motor rotor, and uses the current voltage and the current temperature as indexes to query the efficiency table of the electric drive system corresponding to the current voltage and the current temperature, and determines the current efficiency of the electric drive system based on the efficiency table; Calculate the electric drive requested torque of the electric drive system based on the current efficiency, and control the electric drive system to execute the electric drive requested torque to provide power to the vehicle or to achieve energy recovery; The step of calculating the electric drive requested torque of the electric drive system based on the current efficiency includes: Obtain the allowable power of the electric drive system and the required torque of the vehicle; Calculate the permissible torque of the electric drive system based on the current efficiency and the permissible power. The electric drive requested torque is determined based on the permissible torque, the vehicle required torque, and the maximum torque of the electric drive system. Controlling the electric drive system to execute the requested electric drive torque based on the difference between the actual power of the electric drive system and the allowable power includes: If the difference is a preset value, then the electric drive torque request is executed; If the difference is greater than the preset value, the first efficiency of the electric drive system is determined according to the efficiency table corresponding to the next temperature range of the current voltage and the current temperature, and the electric drive requested torque is re-determined according to the first efficiency. If the difference is less than the preset value, the second efficiency of the electric drive system is determined according to the efficiency table corresponding to the previous temperature range of the current voltage and the current temperature, and the electric drive requested torque is re-determined according to the second efficiency.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, The program is executed by the processor to implement the torque control method as described in any one of claims 1-9.

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