Motor control method and device, vehicle and medium

Abstract

The invention relates to the technical field of intelligent control, and discloses a motor control method and device, a vehicle and a medium, a second temperature threshold value is determined based on the current motor temperature and the current motor temperature change rate, so that the influence of the current motor temperature and the temperature rising speed is considered by adopting a mode of adaptively adjusting the second temperature threshold value; a derating coefficient is determined by using a self-adaptively adjusted second temperature threshold value to obtain a first torque, a second torque is determined by considering the influence of peak power, and actual torque limit values corresponding to a motor under a driving working condition and a power generation working condition are determined by using a smaller value in the first torque and the second torque; the permanent damage of the motor due to overheating can be prevented through the limitation of the actual torque limit value, the problems of winding copper loss and sharp increase of temperature rise rate caused by exceeding peak power can be effectively solved, the service life of the motor is prolonged while the performance of the motor is ensured, and a thermal protection effect can also be achieved under a power generation working condition.

Description

Technical Field

[0001] The present invention relates to the field of intelligent control technology, and in particular to a motor control method, device, vehicle and medium. Background Art

[0002] The motor is a core component of new energy vehicles and plays an important role in the electric drive system. As the requirements for motor performance become increasingly higher, the motor faces severe tests. Long-term, high-load operation of the motor causes the motor temperature to rise sharply. When the motor temperature exceeds the critical temperature, it may lead to the risk of rotor demagnetization and motor stator winding burning, which in turn causes the electric drive force to fail. Summary of the Invention

[0003] In view of this, the present invention provides a motor control method, device, vehicle and medium to solve the problem in the related art that when the motor temperature exceeds the critical temperature, the risk of rotor demagnetization and motor stator winding burning may occur, thereby causing the electric driving force to fail.

[0004] In a first aspect, the present invention provides a motor control method, the method comprising:

[0005] Get the current motor temperature, current motor temperature change rate, current motor speed and peak power of the motor;

[0006] When the current motor temperature is not less than a first temperature threshold, determining a second temperature threshold based on the current motor temperature and the current motor temperature change rate, the second temperature threshold being greater than the first temperature threshold;

[0007] When the current motor temperature is less than the second temperature threshold, calculating a derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold;

[0008] determining a current external characteristic torque value based on the current motor speed, and calculating a first torque based on a product of the current external characteristic torque value and the derating factor;

[0009] Calculating a second torque based on the peak power, the current motor speed, and the derating factor;

[0010] Based on the smaller value of the first torque and the second torque, actual torque limits corresponding to the driving condition and the generating condition are determined, and the operation of the motor is controlled according to the actual torque limits corresponding to the driving condition and the generating condition.

[0011] The present invention determines a second temperature threshold based on the current motor temperature and the current motor temperature change rate, thereby taking into account the influence of the current motor temperature and the temperature rise rate by adaptively adjusting the second temperature threshold. The derating coefficient is determined by using the adaptively adjusted second temperature threshold to obtain the first torque, and the second torque is determined by considering the influence of the peak power. The smaller value of the first torque and the second torque is used to determine the actual torque limit corresponding to the motor under the driving condition and the power generation condition, respectively. The limitation of the actual torque limit can prevent the motor from being permanently damaged due to overheating, and can also effectively alleviate the problems of winding copper loss and temperature rise rate surge caused by exceeding the peak power, while ensuring the motor performance while improving the service life of the motor, and can also play a thermal protection role under the power generation condition.

[0012] In an optional implementation, determining the second temperature threshold based on the current motor temperature and the current motor temperature change rate includes:

[0013] The temperature thresholds corresponding to motor overtemperature faults under different motor temperatures and motor temperature change rates are calibrated to obtain the mapping relationship between different motor temperatures, motor temperature change rates and temperature thresholds;

[0014] Based on the mapping relationship, a second temperature threshold corresponding to the current motor temperature and the current motor temperature change rate is determined.

[0015] The present invention calibrates the temperature thresholds corresponding to motor over-temperature faults under different motor temperatures and motor temperature change rates, thereby obtaining an accurate mapping relationship between motor temperature, motor temperature change rate and temperature thresholds. Based on the mapping relationship, a second temperature threshold that meets the actual operating conditions of the motor and causes an over-temperature fault can be obtained, thereby providing an accurate data basis for temperature protection of the motor, further ensuring the motor performance while increasing the service life of the motor.

[0016] In an optional implementation, the calculating the derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold includes:

[0017] Calculating a first temperature difference between the current motor temperature and the first temperature threshold, and calculating a second temperature difference between the second temperature threshold and the first temperature threshold;

[0018] A derating factor is determined based on a ratio of the first temperature difference to the second temperature difference.

[0019] The present invention obtains the derating coefficient by utilizing the ratio of the temperature difference between the real-time motor temperature and the first temperature threshold to the temperature difference between the second temperature threshold and the first temperature threshold, thereby realizing linear adjustment of the subsequent actual torque limit, ensuring the smoothness of the actual torque adjustment of the motor, avoiding the problem of drastic fluctuations in the motor output power and significant increase in battery energy consumption caused by large-scale adjustment of the motor torque, and improving the vehicle's cruising range. At the same time, an excessively large torque adjustment amplitude will make the vehicle respond too sensitively when driving at low speeds, requiring the driver to control more precisely and easily experiencing a sense of loss of control. The linear and smooth adjustment of the actual torque limit of the motor can improve the user's driving experience during low-speed driving.

[0020] In an optional implementation, the calculating the second torque based on the peak power, the current motor speed, and the derating factor includes:

[0021] Calculating a current peak torque based on the peak power and the current motor speed;

[0022] A second torque is calculated based on a product of the current peak torque and the derating factor.

[0023] The present invention calculates the current peak torque corresponding to the current motor speed using the peak power of the motor, and then obtains the torque limit corresponding to the peak power by multiplying the current peak torque by the derating factor, thereby ensuring that the motor does not exceed its peak power, thereby avoiding the problems of winding copper loss and temperature rise rate surge, and further improving the service life of the motor.

[0024] In an optional embodiment, determining the actual torque limits corresponding to the driving condition and the generating condition respectively based on the smaller value of the first torque and the second torque includes:

[0025] determining a smaller value between the first torque and the second torque as a corresponding maximum actual torque limit value under a driving condition;

[0026] The smaller value between the first torque and the second torque is negated and determined as the minimum actual torque limit corresponding to the power generation condition.

[0027] The present invention determines the smaller value of the first torque and the second torque as the corresponding maximum actual torque limit under the driving condition, thereby ensuring that no matter whether the motor is operating in a high-speed state or a low-speed state, as long as the working torque meets the actual torque limit, the motor can be avoided from overheating and damage, thereby improving the service life of the motor. The present invention also realizes the thermal protection function of the motor under the power generation condition by taking the negative value of the smaller value of the first torque and the second torque and determining it as the corresponding minimum actual torque limit under the power generation condition.

[0028] In an optional embodiment, the method further includes:

[0029] determining whether a smaller value of the first torque and the second torque is greater than a product of the current external characteristic torque value and a set limit coefficient, where the set limit coefficient is greater than 0 and less than or equal to 1;

[0030] When the smaller value of the first torque and the second torque is greater than the product of the current external characteristic torque value and the set limit coefficient, the corresponding minimum actual torque limit under the power generation condition is updated to the torque value obtained by negatively multiplying the current external characteristic torque value and the set limit coefficient.

[0031] The present invention further limits the minimum actual torque limit under power generation conditions by comparing the current external characteristic torque value of the motor with the product of the set limit coefficient under power generation conditions, thereby avoiding damage to the motor caused by excessively high operating torque of the motor and further improving the service life of the motor.

[0032] In an optional embodiment, the method further includes:

[0033] When the current motor temperature is not less than the second temperature threshold, the motor is controlled to output zero torque in both the driving condition and the power generation condition.

[0034] The present invention directly controls the motor to output zero torque under driving and power generation conditions when the current motor temperature is not less than a second temperature threshold, thereby quickly cooling the motor, minimizing damage to the motor, and extending the service life of the motor.

[0035] In an optional embodiment, the method further includes:

[0036] When the current motor temperature is less than a first temperature threshold, determining a maximum actual torque limit corresponding to a driving condition as the current external characteristic torque value, and determining a minimum actual torque limit corresponding to a power generation condition as a torque value obtained by negatively calculating the current external characteristic torque value of the motor;

[0037] The motor is controlled to operate according to the maximum actual torque limit corresponding to the driving condition and the minimum actual torque limit corresponding to the power generation condition.

[0038] The present invention improves the torque capacity of the motor and maximizes the performance of the motor by controlling the motor to operate at the current external characteristic torque value in the driving condition and the negative torque value in the power generation condition when the current motor temperature is lower than the first temperature threshold, because the motor does not have an overheating problem.

[0039] In a second aspect, the present invention provides a motor control device, comprising:

[0040] An acquisition module is used to obtain the current motor temperature, the current motor temperature change rate, the current motor speed and the peak power of the motor;

[0041] a first processing module, configured to determine, when the current motor temperature is not less than a first temperature threshold, a second temperature threshold based on the current motor temperature and the current motor temperature change rate, wherein the second temperature threshold is greater than the first temperature threshold;

[0042] a second processing module, configured to calculate a derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold when the current motor temperature is less than the second temperature threshold;

[0043] a third processing module, configured to determine a current external characteristic torque value based on the current motor speed, and calculate a first torque based on a product of the current external characteristic torque value and the derating factor;

[0044] a fourth processing module, configured to calculate a second torque based on the peak power, the current motor speed, and the derating factor;

[0045] The fifth processing module is used to determine the actual torque limit values ​​corresponding to the driving condition and the power generation condition respectively based on the smaller value of the first torque and the second torque, and to control the operation of the motor according to the actual torque limit values ​​corresponding to the driving condition and the power generation condition respectively.

[0046] In a third aspect, the present invention provides a vehicle, comprising: a controller, wherein:

[0047] The memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method described in the first aspect and any one of its optional embodiments by executing the computer instructions.

[0048] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the method provided in the first aspect or any corresponding embodiment thereof.

[0049] Beneficial effects of the present invention:

[0050] The present invention determines a second temperature threshold based on the current motor temperature and the current motor temperature change rate, thereby taking into account the influence of the current motor temperature and the temperature rise rate by adaptively adjusting the second temperature threshold. The derating coefficient is determined by using the adaptively adjusted second temperature threshold to obtain the first torque, and the second torque is determined by considering the influence of the peak power. The smaller value of the first torque and the second torque is used to determine the actual torque limit corresponding to the motor under the driving condition and the power generation condition, respectively. The limitation of the actual torque limit can prevent the motor from being permanently damaged due to overheating, and can also effectively alleviate the problems of winding copper loss and temperature rise rate surge caused by exceeding the peak power, while ensuring the motor performance while improving the service life of the motor, and can also play a thermal protection role under the power generation condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 is a flow chart of a motor control method according to an embodiment of the present invention;

[0053] Figure 2 is a flow chart of another motor control method according to an embodiment of the present invention;

[0054] Figure 3 is a specific flow chart for determining the torque capability of a motor according to an embodiment of the present invention;

[0055] Figure 4 It is a schematic diagram of the relationship between the motor operating torque and temperature under driving conditions and power generation conditions;

[0056] Figure 5 is a schematic structural diagram of a motor control device according to an embodiment of the present invention;

[0057] Figure 6 2 is a schematic structural diagram of a vehicle controller according to an embodiment of the present invention. DETAILED DESCRIPTION

[0058] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0059] The motor is a core component of new energy vehicles and plays an important role in the electric drive system. As the requirements for motor performance become increasingly higher, the motor faces severe tests. Long-term, high-load operation of the motor causes the motor temperature to rise sharply. When the motor temperature exceeds the critical temperature, it may lead to the risk of rotor demagnetization and motor stator winding burning, which in turn causes the electric drive force to fail.

[0060] In response to the above problems, in related technologies, the technical solution adopted is to set two threshold temperatures according to the allowable temperature of the motor, preset the relationship between the threshold temperature and the motor torque output, and set the hysteresis temperature. The torque and temperature hysteresis loop settings are used to avoid the motor repeatedly starting to reduce torque or fault locking when the threshold temperature jumps. This method can effectively protect the motor from being damaged by overtemperature faults, and also minimize the poor driving experience brought to the driver due to the cessation of torque output due to overtemperature of the motor.

[0061] However, the above solution has the following problems:

[0062] 1. The above solution specifies that torque is reduced when the temperature exceeds a first threshold and falls below a second threshold. However, in actual operating conditions, motor temperature rise curves vary and heat accumulates. This solution only considers the impact of motor temperature on the motor system, not the impact of the speed of motor temperature rise on the motor system. Consequently, it cannot effectively protect the motor.

[0063] 2. The above solution only considers the thermal protection of the motor due to temperature, but does not consider the impact of peak power on the motor system. When the motor operates at a power level exceeding the peak power, it will cause a surge in winding copper loss and temperature rise rate, affecting the motor's service life.

[0064] 3. The above scheme only considers the protection of the motor against overtemperature under driving conditions (positive speed and positive torque), but does not protect the motor against overtemperature under generating conditions (positive speed and negative torque).

[0065] In response to the above problems, an embodiment of the present invention provides a motor control solution, which obtains the current motor temperature, calculates the temperature change rate in real time, and dynamically obtains the second temperature threshold through the temperature change rate. When the motor temperature exceeds the first temperature threshold and is less than the second temperature threshold, the maximum torque capacity 1 is calculated based on the external characteristic torque, motor temperature, the first temperature threshold, and the second temperature threshold. The current motor speed and preset peak power are obtained, and the torque limit value affected by the peak power under the driving condition, namely the maximum torque capacity 2, is calculated. Then, the smaller value between the maximum torque capacity 1 and the maximum torque capacity 2 is determined as the maximum torque limit value under the driving condition, and the corresponding minimum torque limit value under the power generation condition is simultaneously determined.

[0066] The motor control scheme provided by the embodiments of the present invention can prevent permanent damage to the motor due to overheating, ensuring performance while extending its service life. The introduction of a minimum torque limit provides thermal protection even under power generation conditions. A variable second temperature threshold is employed to account for the combined effects of motor temperature and the rate of temperature rise. Peak power limiting effectively mitigates the problems of winding copper loss and temperature rise rates caused by exceeding peak power.

[0067] According to an embodiment of the present invention, an embodiment of a motor control method is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0068] In this embodiment, a motor control method is provided, which can be applied to a vehicle controller such as a single chip microcomputer, MCU or other control chip. Figure 1 is a flow chart of a motor control method according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0069] Step S101 , obtaining the current motor temperature, the current motor temperature change rate, the current motor speed, and the peak power of the motor.

[0070] Specifically, the current motor temperature of the motor can be acquired through temperature monitoring equipment, such as a temperature sensor mounted on a vehicle for measuring the motor temperature. The current motor temperature change rate can be determined by subtracting the motor temperature acquired by the temperature sensor at the current sampling moment from the motor temperature acquired at the previous sampling moment, or by subtracting the motor temperature value read at the current moment from the motor temperature value read after a fixed delay. The present invention is not limited thereto. The peak power of the motor is a fixed parameter of the motor and can be obtained from the motor's operating manual or product specification based on the motor model.

[0071] Step S102 : When the current motor temperature is not less than the first temperature threshold, determining a second temperature threshold based on the current motor temperature and the current motor temperature change rate.

[0072] Among them, the first temperature threshold is the temperature critical value at which the motor may have a potential overheating risk and requires temperature protection control. The temperature critical value can be selected through motor testing or based on manual experience. When the motor temperature is less than the first temperature threshold, the motor does not have an overheating problem, and the second temperature threshold is greater than the first temperature threshold. The second temperature threshold is the temperature critical value that characterizes overheating damage to the motor. When the motor temperature exceeds the temperature critical value, it indicates that the motor begins to have overheating damage problems. The second temperature threshold is closely related to the actual temperature of the motor and the temperature change rate. When the motor is running at the same temperature, the faster the motor heating rate is, the more likely it is to be overheated and damaged, and the smaller the second temperature threshold is. Similarly, when the motor heating rate is the same, the higher the actual temperature of the motor is, the more likely it is to be overheated and damaged, and the smaller the second temperature threshold is.

[0073] Step S103 : when the current motor temperature is less than the second temperature threshold, calculating the derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold.

[0074] Specifically, from the above analysis, it can be seen that when the motor is operating in the temperature range between the first temperature threshold and the second temperature threshold, in order to avoid overheating and damage to the motor, the torque of the motor needs to be limited. Specifically, the derating coefficient can be calculated based on the current motor temperature and the first temperature threshold and the second temperature threshold. The derating coefficient is used to characterize the degree of limitation of the motor's operating torque. The value range of the derating coefficient is between 0 and 1. When the derating coefficient is 1, it indicates that no torque limitation is required. When the derating coefficient is 0, it indicates that the motor output torque is zero. For example, when the derating coefficient is 0.5, it indicates that the motor output torque limitation is 50%.

[0075] Step S104 : determining a current external characteristic torque value based on the current motor speed, and calculating a first torque based on a product of the current external characteristic torque value and a derating factor.

[0076] Specifically, since the relationship between motor speed and torque is known to those skilled in the art, the current external characteristic torque value can be obtained from the motor external characteristic curve using the current motor speed. By using the motor external characteristic curve to select the current external characteristic torque value as the torque limit reference, the motor can be kept within a safe operating range and its output capacity can be maximized.

[0077] Step S105 , calculating the second torque based on the peak power, the current motor speed and the derating factor.

[0078] Specifically, the peak power is the maximum operating power that can avoid problems such as winding copper loss and a surge in temperature rise rate in the motor. Through the peak power and the actual speed of the motor, according to the correspondence between power, speed and torque, another torque limit reference value can be calculated, and then it is further limited by the derating factor to obtain the second torque, providing an accurate data reference for the subsequent determination of the actual torque limit of the motor.

[0079] Step S106: determining actual torque limits corresponding to the driving condition and the generating condition respectively based on the smaller value of the first torque and the second torque, and controlling the operation of the motor according to the actual torque limits corresponding to the driving condition and the generating condition respectively.

[0080] Specifically, in order to ensure the safe operation of the motor under different operating conditions and avoid damage due to overheating of the motor, the actual torque limit of the motor under different operating conditions is set according to the smaller value of the first torque and the second torque, and the operation of the motor is controlled accordingly, thereby realizing the overtemperature protection function of the motor.

[0081] The embodiment of the present invention determines the second temperature threshold based on the current motor temperature and the current motor temperature change rate, thereby taking into account the influence of the current motor temperature and the temperature rise rate by adaptively adjusting the second temperature threshold. The derating coefficient is determined by using the adaptively adjusted second temperature threshold to obtain the first torque, and the second torque is determined considering the influence of the peak power. The smaller value of the first torque and the second torque is used to determine the actual torque limit corresponding to the motor under the driving condition and the power generation condition, respectively. The limitation of the actual torque limit can prevent the motor from being permanently damaged due to overheating, and can also effectively alleviate the problems of winding copper loss and temperature rise rate surge caused by exceeding the peak power, thereby ensuring the motor performance while improving the service life of the motor, and can also play a thermal protection role under the power generation condition.

[0082] According to an embodiment of the present invention, an embodiment of a motor control method is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0083] In this embodiment, a motor control method is also provided, which can be applied to a vehicle controller such as a single chip microcomputer, MCU or other control chip. Figure 2 is a flow chart of a motor control method according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0084] Step S201, obtain the current motor temperature, current motor temperature change rate, current motor speed and peak power of the motor. Figure 1 The description of step S101 is omitted here.

[0085] Step S202 : When the current motor temperature is not less than the first temperature threshold, determining a second temperature threshold based on the current motor temperature and the current motor temperature change rate.

[0086] The second temperature threshold is greater than the first temperature threshold.

[0087] Specifically, the above step S202 includes:

[0088] Step S2021 , calibrating the temperature thresholds corresponding to motor over-temperature faults under different motor temperatures and motor temperature change rates, and obtaining mapping relationships between different motor temperatures, motor temperature change rates, and temperature thresholds.

[0089] Specifically, by conducting several tests on the same model of motor under different motor temperatures and different motor temperature change rates, the temperature value at which the motor is overheated and damaged can be obtained. Then, the data can be integrated by taking the smaller or average value of the temperature values ​​obtained under the same conditions, and the temperature thresholds under different conditions can be calibrated to obtain the mapping relationship between different motor temperatures, motor temperature change rates and temperature thresholds. For example, the mapping relationship can be stored in a table form.

[0090] Step S2022: Determine a second temperature threshold corresponding to the current motor temperature and the current motor temperature change rate based on the mapping relationship.

[0091] For example, the second temperature threshold corresponding to the current motor temperature and the current motor temperature change rate may be searched in the table storing the mapping relationship.

[0092] The embodiment of the present invention calibrates the temperature thresholds corresponding to motor over-temperature faults under different motor temperatures and motor temperature change rates, thereby obtaining an accurate mapping relationship between motor temperature, motor temperature change rate and temperature thresholds. Based on the mapping relationship, a second temperature threshold that meets the actual operating conditions of the motor and causes an over-temperature fault can be obtained, thereby providing an accurate data basis for providing temperature protection for the motor, further ensuring the motor performance while improving the service life of the motor.

[0093] Step S203 : When the current motor temperature is less than the second temperature threshold, a derating factor is calculated based on the current motor temperature, the first temperature threshold, and the second temperature threshold.

[0094] Specifically, the above step S203 includes:

[0095] Step S2031 , calculating a first temperature difference between the current motor temperature and the first temperature threshold, and calculating a second temperature difference between the second temperature threshold and the first temperature threshold.

[0096] Step S2032: Determine a derating factor based on the ratio of the first temperature difference to the second temperature difference.

[0097] For example, assuming that the current motor temperature is A, the first temperature threshold is B1, and the second temperature threshold is B2, the derating factor C=(A-B1) / (B1-B2).

[0098] The embodiment of the present invention obtains the derating coefficient by utilizing the ratio of the temperature difference between the real-time motor temperature and the first temperature threshold to the temperature difference between the second temperature threshold and the first temperature threshold, thereby realizing linear adjustment of the subsequent actual torque limit, ensuring the smoothness of the actual torque adjustment of the motor, avoiding the problem of drastic fluctuations in the motor output power and significant increase in battery energy consumption caused by large-scale adjustment of the motor torque, and improving the vehicle's cruising range. At the same time, an excessively large torque adjustment amplitude will make the vehicle respond too sensitively when driving at low speeds, requiring the driver to operate more precisely and easily experiencing a sense of loss of control. The linear and smooth adjustment of the actual torque limit of the motor can improve the user's driving experience during low-speed driving.

[0099] Step S204: Determine the current external characteristic torque value based on the current motor speed, and calculate the first torque based on the product of the current external characteristic torque value and the derating factor. Figure 1 The description of step S104 is omitted here.

[0100] Step S205 , calculating the second torque based on the peak power, the current motor speed, and the derating factor.

[0101] Specifically, the above step S205 includes:

[0102] Step S2051: Calculate the current peak torque based on the peak power and the current motor speed.

[0103] Specifically, the current peak torque can be calculated based on the corresponding relationship between power, speed and torque.

[0104] Step S2052: Calculate the second torque based on the product of the current peak torque and the derating factor.

[0105] The embodiment of the present invention uses the peak power of the motor to calculate the current peak torque corresponding to the current motor speed, and then obtains the torque limit corresponding to the peak power by multiplying the current peak torque by the derating factor, thereby ensuring that the motor operation does not exceed its peak power, thereby avoiding the problems of winding copper loss and temperature rise rate surge, and further improving the service life of the motor.

[0106] Step S206: Based on the smaller value of the first torque and the second torque, determine the actual torque limit values ​​corresponding to the driving condition and the generating condition, and control the operation of the motor according to the actual torque limit values ​​corresponding to the driving condition and the generating condition.

[0107] Specifically, in step S206, determining the actual torque limits corresponding to the driving condition and the generating condition, respectively, based on the smaller value of the first torque and the second torque, specifically includes:

[0108] In step a1, the smaller value of the first torque and the second torque is determined as the maximum actual torque limit corresponding to the driving condition.

[0109] Step a2: Negate the smaller value of the first torque and the second torque to determine it as the minimum actual torque limit corresponding to the power generation condition.

[0110] The embodiment of the present invention determines the smaller value of the first torque and the second torque as the corresponding maximum actual torque limit under the driving condition, thereby ensuring that no matter whether the motor is operating in a high-speed state or a low-speed state, as long as the working torque meets the actual torque limit, the motor can be avoided from overheating and damage, thereby improving the service life of the motor. The embodiment of the present invention also realizes the thermal protection function of the motor under the power generation condition by taking the negative value of the smaller value of the first torque and the second torque and determining it as the corresponding minimum actual torque limit under the power generation condition.

[0111] In some optional implementations, before executing step a2, step S206 further includes the following steps:

[0112] Step a3: Determine whether the smaller value of the first torque and the second torque is greater than the product of the current external characteristic torque value and the set limit coefficient.

[0113] The limit coefficient is set to be greater than 0 and less than or equal to 1. For example, the limit coefficient can be selected based on experience, such as 0.8.

[0114] Specifically, the current external characteristic torque value of the motor is the driving peak torque value that the motor can theoretically safely output at the current speed. Therefore, when limiting the torque of the motor, the influence of the driving peak torque of the motor also needs to be considered to avoid damage to the motor due to excessive operating torque of the motor.

[0115] In step a4, when the smaller value of the first torque and the second torque is greater than the product of the current external characteristic torque value and the set limit coefficient, the corresponding minimum actual torque limit under the power generation condition is updated to the torque value obtained by negatively multiplying the current external characteristic torque value and the set limit coefficient.

[0116] Furthermore, when the smaller value of the first torque and the second torque is not greater than the product of the current external characteristic torque value and the set limit coefficient, the above step a2 is performed.

[0117] The embodiment of the present invention further limits the minimum actual torque limit under the power generation condition by comparing the current external characteristic torque value of the motor with the product of the set limit coefficient under the power generation condition, thereby avoiding damage to the motor caused by excessively high operating torque of the motor and further improving the service life of the motor.

[0118] In some optional implementations, the motor control method provided by the embodiment of the present invention further includes the following steps:

[0119] Step b1: When the current motor temperature is not less than a second temperature threshold, the motor is controlled to output zero torque in both the driving condition and the power generation condition.

[0120] The embodiment of the present invention directly controls the motor to output zero torque under driving conditions and power generation conditions when the current motor temperature is not less than a second temperature threshold, so as to quickly cool the motor, minimize damage to the motor, and extend the service life of the motor.

[0121] In some optional implementations, the motor control method provided by the embodiment of the present invention further includes the following steps:

[0122] In step c1, when the current motor temperature is less than a first temperature threshold, the maximum actual torque limit corresponding to the driving condition is determined to be the current external characteristic torque value, and the minimum actual torque limit corresponding to the generating condition is determined to be the negative of the current external characteristic torque value.

[0123] Specifically, when the motor temperature is lower than the first temperature threshold, it indicates that there is no risk of overheating in the motor, and no additional restrictions are imposed on the motor torque. As long as the motor torque operates within the current external characteristic torque value of the motor, that is, within the safe operating torque range, it can ensure that the motor operation meets driving requirements.

[0124] Step c2: controlling the operation of the motor according to the maximum actual torque limit corresponding to the driving condition and the minimum torque limit corresponding to the generating condition.

[0125] In the embodiment of the present invention, when the current motor temperature is lower than the first temperature threshold, since the motor does not have an overheating problem, the motor can be controlled to operate at the current external characteristic torque value in the driving condition, and can operate at the torque value which is the negative of the current external characteristic torque value in the power generation condition, thereby improving the torque capacity of the motor and maximizing the performance of the motor.

[0126] The specific working process of the motor control solution provided by the embodiment of the present invention will be described in detail below with reference to specific application examples.

[0127] For example, Figure 3 As shown, the process flow for determining the motor torque capability includes:

[0128] S01: Real-time acquisition of motor temperature and motor speed.

[0129] Specifically, the motor temperature refers to the motor stator temperature, and the motor speed is obtained by decoding the feedback signal collected by the rotary transformer through software.

[0130] S02: Output maximum minimum torque capacity 1 when the motor temperature is lower than the first temperature threshold.

[0131] Specifically, the maximum torque capacity 1 at this time is the driving peak torque, that is, the above-mentioned current external characteristic torque value, and the minimum torque capacity 1 is the negative of the power generation peak torque. The power generation peak torque is equal to the driving peak torque, that is, when the motor temperature is lower than the first temperature threshold, the motor torque is not limited.

[0132] S03: Calculate the temperature rise rate according to the temperature to obtain a second temperature threshold.

[0133] Specifically, the motor temperature t0 is acquired in real time in each execution cycle, and the currently acquired temperature is delayed to obtain t1. The difference between t1 and t0 is the motor temperature change rate, and the second temperature threshold is obtained by looking up the table according to the motor temperature change rate.

[0134] S04: When the motor temperature exceeds the first temperature threshold but is lower than the second temperature threshold, the maximum and minimum torque capabilities 1 are calculated based on the relationship between the external characteristic torque and the motor temperature.

[0135] Specifically, the derating factor and the maximum and minimum torque capacity values ​​1 are calculated based on the current external characteristic torque value, the current motor temperature, the first temperature threshold, and the second temperature threshold. The derating factor is the ratio of the difference between the current temperature and the first temperature threshold to the difference between the second temperature threshold and the first temperature threshold. The maximum and minimum torque capacity 1 is the derating factor multiplied by the external characteristic torque. A fault flag is set to 1 when the motor temperature is greater than or equal to the first temperature threshold, and to 0 when the motor temperature is less than the first temperature threshold minus the offset.

[0136] S05: If the current motor temperature reaches the second temperature threshold, the motor output torque capacity 1 is 0.

[0137] Specifically, the maximum torque capacity 1 and the minimum torque capacity 1 at this time are 0, that is, when the motor temperature is greater than or equal to the second temperature threshold, the derating coefficient is 0.

[0138] S06: Calculate the maximum and minimum torque capabilities based on the derating factor, peak power, and motor speed.

[0139] Specifically, the maximum torque capacity 2 refers to the maximum torque capacity trq at the current motor speed calculated based on the correspondence between peak power, speed and torque, and then the maximum torque capacity 2 is obtained by multiplying trq by the derating factor obtained in S04. The minimum torque capacity 2 is the maximum torque capacity 2 with a negative sign.

[0140] S07: Torque capacity 1 and torque capacity 2 take the smaller output.

[0141] Specifically, the final maximum and minimum torque capacities are calculated based on the maximum torque capacity 1 and minimum torque capacity 1 calculated in S02, S04, and S05, and then based on the maximum torque capacity 2 and minimum torque capacity 2 calculated in S06. The smaller of the maximum torque capacity 1 and the maximum torque capacity 2 is used to obtain the final maximum torque capacity, which is used to limit the actual torque of the motor under driving conditions and effectively prevent a continuous and rapid increase in motor temperature. The smaller of the absolute values ​​of the minimum torque capacity 1 and the minimum torque capacity 2 is used, and the result is recorded as torque capacity 3. The driving peak torque is multiplied by the set limit coefficient to obtain torque capacity 4. The smaller of the torque capacity 3 and the torque capacity 4 is then taken as the negative to obtain the final minimum torque capacity, which is used to limit the actual torque of the motor under generating conditions and effectively prevent a continuous and rapid increase in motor temperature.

[0142] For example, the relationship between the actual torque limit and temperature of the motor under the driving condition and the generating condition is as follows: Figure 4 shown. Figure 4 Middle T nax1 Indicates the peak driving torque of the motor, T max2 represents the peak torque of the motor, and T max1 =T max2 , t1 and t2 represent the first temperature threshold and the second temperature threshold, respectively.

[0143] In this embodiment, a motor control device is also provided, which is used to implement the above-mentioned embodiments and preferred embodiments. The details that have been described will not be repeated here. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.

[0144] The embodiment of the present invention provides a motor control device, such as Figure 5 As shown, the device includes:

[0145] An acquisition module 501 is used to acquire the current motor temperature, the current motor temperature change rate, the current motor speed, and the peak power of the motor;

[0146] A first processing module 502 is configured to determine a second temperature threshold based on the current motor temperature and the current motor temperature change rate when the current motor temperature is not less than the first temperature threshold, wherein the second temperature threshold is greater than the first temperature threshold;

[0147] A second processing module 503 is configured to calculate a derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold when the current motor temperature is less than the second temperature threshold;

[0148] a third processing module 504 for determining a current external characteristic torque value based on the current motor speed, and calculating a first torque based on a product of the current external characteristic torque value and a derating factor;

[0149] A fourth processing module 505 is configured to calculate a second torque based on the peak power, the current motor speed, and the derating factor;

[0150] The fifth processing module 506 is used to determine the actual torque limit values ​​corresponding to the driving condition and the power generation condition respectively based on the smaller value of the first torque and the second torque, and control the operation of the motor according to the actual torque limit values ​​corresponding to the driving condition and the power generation condition respectively.

[0151] In some optional implementations, the first processing module 502 includes:

[0152] The first processing unit is used to calibrate the temperature threshold corresponding to the motor over-temperature fault under the motor temperature change rate, and obtain the mapping relationship between different motor temperatures, motor temperature change rates and temperature thresholds;

[0153] The second processing unit is configured to determine, based on the mapping relationship, a second temperature threshold corresponding to the current motor temperature and the current motor temperature change rate.

[0154] In some optional implementations, the second processing module 503 includes:

[0155] a third processing unit, configured to calculate a first temperature difference between a current motor temperature and a first temperature threshold, and to calculate a second temperature difference between a second temperature threshold and the first temperature threshold;

[0156] The fourth processing unit is configured to determine a derating factor based on a ratio of the first temperature difference to the second temperature difference.

[0157] In some optional implementations, the fourth processing module 505 includes:

[0158] a fifth processing unit, configured to calculate a current peak torque based on the peak power and the current motor speed;

[0159] The sixth processing unit is configured to calculate the second torque based on a product of the current peak torque and the derating factor.

[0160] In some optional implementations, the fifth processing module 506 includes:

[0161] a seventh processing unit, configured to determine the smaller value of the first torque and the second torque as the corresponding maximum actual torque limit value under the driving condition;

[0162] The eighth processing unit is configured to negate the smaller value of the first torque and the second torque to determine the smaller value as the minimum actual torque limit corresponding to the power generation condition.

[0163] In some optional implementations, the fifth processing module 506 further includes:

[0164] A ninth processing unit, configured to determine whether the smaller value of the first torque and the second torque is greater than the product of the current external characteristic torque value and a set limit coefficient, where the set limit coefficient is greater than 0 and less than or equal to 1;

[0165] The tenth processing unit is used to update the corresponding minimum actual torque limit under the power generation condition to the torque value obtained by negatively multiplying the current external characteristic torque value and the set limit coefficient when the smaller value between the first torque and the second torque is greater than the product of the current external characteristic torque value and the set limit coefficient.

[0166] In some optional implementations, the motor control device provided by the embodiment of the present invention further includes:

[0167] The sixth processing module is used to control the motor to output zero torque in both the driving condition and the power generation condition when the current motor temperature is not less than the second temperature threshold.

[0168] In some optional implementations, the motor control device provided by the embodiment of the present invention further includes:

[0169] a seventh processing module, configured to, when the current motor temperature is less than a first temperature threshold, determine that a maximum actual torque limit corresponding to the driving condition is the current external characteristic torque value, and determine that a minimum actual torque limit corresponding to the generating condition is the torque value obtained by negatively dividing the current external characteristic torque value;

[0170] The eighth processing module is used to control the operation of the motor according to the maximum actual torque limit corresponding to the driving condition and the minimum actual torque limit corresponding to the power generation condition.

[0171] The further functional description of each of the above modules and units is the same as that of the above corresponding method embodiments and will not be repeated here.

[0172] An embodiment of the present invention further provides a vehicle, the vehicle including a controller, such as Figure 6As shown, the controller includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. The various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process instructions executed in the computer device, including instructions stored in or on the memory to display graphical information of a GUI on an external input / output device (such as a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 6 A processor 10 is taken as an example.

[0173] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0174] The memory 20 stores instructions that can be executed by at least one processor 10, so as to enable at least one processor 10 to execute the method shown in the above embodiment.

[0175] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created based on the use of a computer device for displaying a small program landing page, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0176] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0177] The controller further includes a communication interface 30 for the vehicle to communicate with other devices or a communication network.

[0178] The embodiment of the present invention also provides a computer-readable storage medium. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0179] A portion of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the form in which the computer program instruction exists in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc. Accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium that can be accessed by the computer.

[0180] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A motor control method, characterized in that: The method comprises: Get the current motor temperature, current motor temperature change rate, current motor speed and peak power of the motor; When the current motor temperature is not less than a first temperature threshold, determining a second temperature threshold based on the current motor temperature and the current motor temperature change rate, the second temperature threshold being greater than the first temperature threshold; When the current motor temperature is less than the second temperature threshold, calculating a derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold; determining a current external characteristic torque value based on the current motor speed, and calculating a first torque based on a product of the current external characteristic torque value and the derating factor; Calculating a second torque based on the peak power, the current motor speed, and the derating factor; Based on the smaller value of the first torque and the second torque, actual torque limits corresponding to the driving condition and the generating condition are determined, and the operation of the motor is controlled according to the actual torque limits corresponding to the driving condition and the generating condition.

2. The method according to claim 1, characterized in that The determining the second temperature threshold based on the current motor temperature and the current motor temperature change rate includes: The temperature thresholds corresponding to motor overtemperature faults under different motor temperatures and motor temperature change rates are calibrated to obtain the mapping relationship between different motor temperatures, motor temperature change rates and temperature thresholds; Based on the mapping relationship, a second temperature threshold corresponding to the current motor temperature and the current motor temperature change rate is determined.

3. The method according to claim 1, characterized in that The calculating the derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold includes: Calculating a first temperature difference between the current motor temperature and the first temperature threshold, and calculating a second temperature difference between the second temperature threshold and the first temperature threshold; A derating factor is determined based on a ratio of the first temperature difference to the second temperature difference.

4. The method according to claim 1, wherein The calculating the second torque based on the peak power, the current motor speed, and the derating factor includes: Calculating a current peak torque based on the peak power and the current motor speed; A second torque is calculated based on a product of the current peak torque and the derating factor.

5. The method according to any one of claims 1 to 4, characterized in that The determining, based on the smaller value of the first torque and the second torque, actual torque limits corresponding to the driving condition and the generating condition, respectively, includes: determining a smaller value between the first torque and the second torque as a corresponding maximum actual torque limit value under a driving condition; The smaller value between the first torque and the second torque is negated and determined as the minimum actual torque limit corresponding to the power generation condition.

6. The method according to claim 5, characterized in that The method further comprises: determining whether a smaller value of the first torque and the second torque is greater than a product of the current external characteristic torque value and a set limit coefficient, where the set limit coefficient is greater than 0 and less than or equal to 1; When the smaller value of the first torque and the second torque is greater than the product of the current external characteristic torque value and the set limit coefficient, the corresponding minimum actual torque limit under the power generation condition is updated to the torque value obtained by negatively multiplying the current external characteristic torque value and the set limit coefficient.

7. The method according to claim 1, characterized in that The method further comprises: When the current motor temperature is not less than the second temperature threshold, the motor is controlled to output zero torque in both the driving condition and the power generation condition.

8. The method according to claim 1, characterized in that When the current motor temperature is less than a first temperature threshold, determining a maximum actual torque limit corresponding to the driving condition to be the current external characteristic torque value, and determining a minimum actual torque limit corresponding to the generating condition to be the torque value obtained by negatively calculating the current external characteristic torque value; The motor is controlled to operate according to the maximum actual torque limit corresponding to the driving condition and the minimum torque limit corresponding to the power generation condition.

9. A motor control device, characterized in that: The device comprises: An acquisition module is used to obtain the current motor temperature, the current motor temperature change rate, the current motor speed and the peak power of the motor; a first processing module, configured to determine, when the current motor temperature is not less than a first temperature threshold, a second temperature threshold based on the current motor temperature and the current motor temperature change rate, wherein the second temperature threshold is greater than the first temperature threshold; a second processing module, configured to calculate a derating factor based on the current motor temperature, the first temperature threshold, and the second temperature threshold when the current motor temperature is less than the second temperature threshold; a third processing module, configured to determine a current external characteristic torque value based on the current motor speed, and calculate a first torque based on a product of the current external characteristic torque value and the derating factor; a fourth processing module, configured to calculate a second torque based on the peak power, the current motor speed, and the derating factor; The fifth processing module is used to determine the actual torque limit values ​​corresponding to the driving condition and the power generation condition respectively based on the smaller value of the first torque and the second torque, and to control the operation of the motor according to the actual torque limit values ​​corresponding to the driving condition and the power generation condition respectively.

10. A vehicle, characterized in that: The vehicle includes a controller, the controller including: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method according to any one of claims 1 to 8 by executing the computer instructions.

11. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the method according to any one of claims 1 to 8.

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