Lameness control method

Abstract

This invention discloses a limp-drive control method, relating to the field of motor control technology. The limp-drive control method includes determining whether a motor sensor is in a fault state based on its detection parameters; if in a fault state, determining the motor's operating heat based on its operating parameters; determining the motor's heat dissipation based on its physical parameters; determining the motor's actual temperature based on the operating heat and heat dissipation; and dynamically adjusting the motor's operating power based on the actual temperature to enable limp-drive operation. The limp-drive control method provided by this invention effectively improves vehicle mobility under fault conditions and avoids unnecessary operational interruptions. It solves the problem of vehicles directly breaking down after a temperature sensor failure in related technologies, achieving the technical effect of maintaining limited vehicle driving capability while ensuring safety.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a limp control method. Background Technology

[0002] In the field of motor thermal management and safety control for new energy vehicles, in order to ensure the reliable operation of the drive motor under complex working conditions, it is necessary to prevent it from being damaged due to overheating while maximizing the continuity of vehicle operation.

[0003] In existing technologies, negative temperature coefficient thermistor sensors, typically mounted directly on the motor stator windings, are used to monitor temperature and feed the measured values ​​back to the motor controller. The controller then executes appropriate overheat protection strategies based on a comparison of the measured temperature value with a preset threshold. This method, relying on direct measurement from a single physical sensor, is a common approach for achieving motor thermal protection.

[0004] However, this solution is limited by the sensor's inherent operating characteristics. Operating in harsh environments of high temperature and high vibration for extended periods poses a risk of short circuits, open circuits, or signal drift. Once the sensor fails, the protection strategies commonly employed are often simplistic: either immediately triggering hard protection leading to power interruption and vehicle breakdown, or using a fixed derating factor to limit power output. This impacts vehicle operating efficiency and also carries the risk of inadequate protection due to inaccurate reflection of the motor's actual thermal state, posing safety hazards, or overly conservative protection failing to fully utilize the motor's remaining safe operating capacity. Summary of the Invention

[0005] The main objective of this invention is to propose a limp control method, which aims to solve the technical problems in the prior art where, after sensor failure, the actual thermal state of the motor cannot be accurately reflected, resulting in insufficient protection and potential safety hazards, or the protection is too conservative and fails to fully utilize the motor's remaining safe operating capacity.

[0006] To achieve the above objectives, the present invention proposes a limp control method, the limp control method comprising: The motor detection device is determined to be in a faulty state based on its detection parameters. In the case of the aforementioned fault state, the operating heat of the motor is determined based on the motor's operating parameters; Based on the physical parameters of the motor, determine the heat dissipation of the motor; The actual temperature of the motor is determined based on the operating heat and the heat dissipation. The operating power of the motor is dynamically adjusted according to the actual temperature to enable the motor to operate in a limp-mode.

[0007] In one embodiment, determining whether the motor detection device is in a faulty state based on the detection parameters of the motor detection device includes: The detection parameters of the motor detection device are used to determine whether the detection parameters of the motor detection device are within the range of a preset threshold. When the detection parameter is within the range of the preset threshold, obtain the duration and / or number of times the detection parameter is within the preset threshold; If the duration exceeds a preset duration and / or the number of occurrences exceeds a preset number, the motor detection device is determined to be in a fault state.

[0008] In one embodiment, the detection parameters include sampling voltage or sampling temperature; If the duration exceeds a preset duration and / or the number of occurrences exceeds a preset number, the motor detection component is determined to be in a fault state, including: If the sampling voltage is greater than the first preset voltage and the duration is greater than the first preset duration, the motor is determined to be in a first type of fault state. If the sampling voltage is less than the second preset voltage and the duration is greater than the second preset duration, the motor is determined to be in a second type of fault state. If the sampling temperature is greater than the first preset temperature and the duration is greater than the third preset duration, the motor detection is determined to be a third type of fault state. If the sampling temperature is lower than the second preset temperature and the duration is greater than the fourth preset duration, the motor is determined to be in the third type of fault state. Wherein, the second preset temperature is lower than the first preset temperature, and the second preset voltage is lower than the first preset voltage.

[0009] In one embodiment, the detection parameter further includes a temperature change rate determined based on the sampling temperature; Determining the motor detection device to be in a fault state when the duration exceeds a preset duration and / or the number of occurrences exceeds a preset number further includes: If the temperature change rate is greater than a first preset change rate and the number of consecutive occurrences is greater than a first preset number of occurrences, the motor detection is determined to be a fourth type of fault state. If the temperature change rate is less than the second preset change rate and the duration is greater than the fifth preset duration, the motor is determined to be in a fifth type of fault state.

[0010] In one embodiment, the operating parameters include input voltage, input current, motor speed, and motor torque; The operating heat of the motor is determined based on its operating parameters, including: The input power of the motor is determined based on the input voltage and input current; The motor efficiency is determined based on the motor speed and the motor torque; The operating heat is determined based on the input power and the motor efficiency.

[0011] In one embodiment, the physical parameters include the heat transfer area of ​​the motor, the thickness of the heat transfer path, the thermal conductivity coefficient, and the convective heat transfer coefficient. Based on the physical parameters of the motor, the heat dissipation of the motor is determined, including: The first sub-heat dissipation of the motor is determined based on the heat transfer area, heat transfer path thickness, and thermal conductivity coefficient. The second sub-heat dissipation of the motor is determined based on the heat transfer area and the convective heat transfer coefficient. The heat dissipation is determined based on the first sub-heat dissipation and the second sub-heat dissipation.

[0012] In one embodiment, the motor further includes a heat sink; Determining the heat dissipation based on the first sub-heat dissipation and the second sub-heat dissipation includes: The third sub-heat dissipation is determined based on the heat dissipation power of the radiator. The heat dissipation power is determined by the temperature difference between the inlet and outlet of the radiator and the specific heat capacity and density of the cooling medium. The heat dissipation is determined based on the first sub-heat dissipation, the second sub-heat dissipation, and the third sub-heat dissipation.

[0013] In one embodiment, dynamically adjusting the operating power of the motor according to the actual temperature to enable limp-out operation of the motor includes: When the actual temperature is less than or equal to the safe temperature threshold, the rated power of the motor shall be used as the operating power. If the actual temperature is greater than the safe temperature threshold but less than or equal to the warning temperature threshold, the operating power is determined based on the actual temperature. If the actual temperature is greater than the warning temperature threshold, the operating power of the motor will be adjusted to 0.

[0014] In one embodiment, determining the operating power based on the actual temperature includes: An adjustment coefficient is determined based on the actual temperature, wherein the adjustment coefficient is proportional to the actual temperature; The operating power is determined based on the rated power and the adjustment coefficient.

[0015] In one embodiment, after the step of adjusting the operating power of the motor to 0, the method further includes: Wait for a preset cooling time, and determine the actual temperature based on the preset cooling time; When the actual temperature is less than or equal to the safe temperature threshold, the rated power of the motor shall be used as the operating power.

[0016] The limp-drive control method provided by this invention improves the temperature detection and power control stages after sensor failure. Without sacrificing motor safety protection, it effectively enhances vehicle mobility under fault conditions and avoids unnecessary operational interruptions. It solves the problem of vehicles directly breaking down after temperature sensor failure in related technologies, achieving the technical effect of maintaining limited vehicle driving capability while ensuring safety. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating a limp control method provided in an embodiment of the present invention.

[0019] Figure 2 This is a flowchart illustrating a limp control method provided in another embodiment of the present invention.

[0020] Figure 3 This is a flowchart illustrating a limp control method provided in another embodiment of the present invention.

[0021] Figure 4 This is a flowchart illustrating a limp control method provided in another embodiment of the present invention.

[0022] Figure 5 This is a flowchart illustrating a limp control method provided in another embodiment of the present invention.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0026] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0027] This invention proposes a limp-drive control method. This method can be applied to various types of vehicles. Specifically, the vehicle system mainly includes a motor providing power, a motor controller, an NTC temperature sensor, a cooling system, and a vehicle dashboard. The motor is connected to the motor controller via a signal line to receive drive signals from the controller and output torque. The NTC temperature sensor is physically mounted on the stator windings of the drive motor to measure the winding temperature and transmits the voltage signal characterizing the temperature to the motor controller via a signal line. Some vehicle models are equipped with a cooling system, or some motors are equipped with built-in radiators. The cooling system may include, for example, a cooling pump, a radiator, and circulation pipes. These pipes flow through cooling channels within the motor housing to remove heat generated by the motor. The vehicle dashboard communicates with the motor controller via an onboard network to display vehicle status and fault information. The motor controller, as the core processing unit, has a built-in microcontroller unit. It is responsible for collecting data such as the motor's input voltage, input current, motor speed, output torque, as well as the inlet and outlet temperatures of the cooling system or radiator coolant and data from the NTC sensor. It then executes a predetermined control algorithm to generate power or torque control commands for the drive motor.

[0028] Please see Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the limp control method of the present invention. The limp control method specifically includes the following steps: Step S10: Determine whether the motor detection device is in a fault state based on the detection parameters of the motor detection device.

[0029] In this application, the vehicle has a limp mode. When the method controls the motor to operate in limp mode, the vehicle can be considered to have entered limp mode. Limp mode refers to a restricted operating state in which the vehicle drive system actively limits its power output performance to maintain basic driving capability after detecting a specific fault. For example, this can manifest as a limited maximum speed, reduced acceleration, or output power limited to a certain percentage below the rated value. Its purpose is to allow the vehicle to travel to a repair station at a lower speed while ensuring safety.

[0030] The motor's temperature signal is monitored in real time by an NTC sensor. This temperature signal is converted from an analog voltage signal acquired by the NTC sensor to obtain an accurate digital temperature value and the rate of change of that temperature value. When one or more of these signals continuously exceed their reasonable threshold range, the NTC sensor is determined to be faulty, triggering subsequent temperature calculations. This invention then controls the vehicle to enter limp mode.

[0031] Only when it is confirmed that the direct temperature information provided by the NTC sensor is unreliable is it necessary to detect the motor's operating parameters and accurately calculate the motor's operating heat using these parameters. This avoids unnecessary computational overhead when the NTC sensor is functioning normally and ensures the accuracy of fault diagnosis.

[0032] Fault diagnosis can be achieved in various ways, not limited to a single specific logic. For example, fault diagnosis can include open-circuit fault detection, short-circuit fault detection, range failure fault detection, and signal anomaly fault detection. Adopting this categorized, multi-criteria diagnostic approach can improve the accuracy and robustness of fault identification, avoiding functional switching oscillations caused by false triggering of a single criterion.

[0033] Step S20: In the case of the fault state, determine the operating heat of the motor based on the motor's operating parameters.

[0034] The core of this embodiment is to construct and solve the thermal balance equation of the motor. After the NTC sensor is diagnosed as faulty, the operating parameters of the motor are collected and the operating heat generated by the motor per unit time is calculated through the operating parameters.

[0035] Step S30: Determine the heat dissipation of the motor based on its physical parameters.

[0036] During motor operation, heat is generated. Simultaneously, due to the motor's physical characteristics or the assistance of a cooling system, heat is dissipated during operation. The corresponding heat dissipation is calculated based on the motor's physical parameters.

[0037] Step S40: Determine the actual temperature of the motor based on the operating heat and the heat dissipation.

[0038] The difference between the operating heat and the heat dissipation is calculated, and this difference is the actual heat absorbed by the motor. This difference is then used as an equivalent value to the actual temperature of the motor after its own temperature rise.

[0039] Step S50: Dynamically adjust the operating power of the motor according to the actual temperature to make the motor operate in a limp-out manner.

[0040] After confirming a fault in the NTC sensor, the vehicle enters limp mode. In limp mode, the temperature value calculated based on operating and physical parameters is used as the actual motor temperature. The motor's operating power is adjusted in real time based on this actual temperature. When the actual temperature is closer to the motor's rated temperature, the motor's operating power is reduced to prevent excessive heat generation that could cause the actual temperature to exceed the rated temperature. Conversely, when the difference between the actual and rated temperatures is greater, the motor's operating power is appropriately increased to maximize vehicle speed within permissible limits.

[0041] By adjusting the motor's operating power in real time according to the actual temperature, the vehicle speed fluctuates, thus maintaining vehicle power in a "limp" manner to meet basic mobility needs.

[0042] Further, please refer to Figure 2 , Figure 2 This is a flowchart illustrating the second embodiment of the limp control method of the present invention. Step S10 includes: Step S11: Determine whether the detection parameters of the motor detection device are within the range of a preset threshold based on the detection parameters of the motor detection device.

[0043] In this embodiment, fault diagnosis refers to the process of determining whether an NTC sensor has lost its normal temperature measurement function by analyzing the electrical characteristics or physical rationality of the NTC sensor's output signal. The reasonable threshold refers to the boundary value used to distinguish between normal and abnormal signals, determined based on the NTC sensor's working principle, the motor's operating temperature range, and thermal inertia. These values ​​can be preset through experimental calibration or theoretical calculation. In this embodiment, the boundary value for abnormal signals, i.e., the preset threshold, is preset.

[0044] Step S12: When the detection parameter is within the range of the preset threshold, obtain the duration and / or number of times the detection parameter is within the preset threshold.

[0045] Step S13: If the duration is greater than the preset duration and / or the number of occurrences is greater than the preset number of occurrences, the motor detection device is determined to be in a fault state.

[0046] The core of fault diagnosis lies in identifying whether the NTC sensor signal has deviated from a state that can characterize the true temperature.

[0047] Specifically, the detection parameters include sampling voltage or sampling temperature. Step S12 includes: Step S121: If the sampling voltage is greater than the first preset voltage and the duration is greater than the first preset duration, determine that the motor is detected as a first type of fault state.

[0048] When the sampling voltage U is continuously higher than the preset first preset voltage U h If the duration t exceeding the first preset voltage exceeds the first preset duration t1, it indicates that the sensor is in a fault state, which is a first type of fault, i.e., an open circuit fault. The first preset duration is calibrated based on the stabilization duration, and the second preset duration, etc., mentioned below can also be calibrated based on their corresponding stabilization durations.

[0049] Step S122: If the sampling voltage is less than the second preset voltage and the duration is greater than the second preset duration, determine that the motor is detected as a second type of fault state.

[0050] When the sampling voltage U remains lower than the preset first preset voltage U L If the duration t of the voltage being lower than the first preset voltage exceeds the second preset duration t2, then the sensor is in a fault state, which is a second type of fault, namely a short circuit fault.

[0051] Step S123: If the sampling temperature is greater than the first preset temperature and the duration is greater than the third preset duration, determine that the motor is detected as a third type of fault state.

[0052] When the sampling temperature T is continuously higher than the preset first preset temperature T max If the duration t of the temperature being below the first preset temperature exceeds the third preset duration t3, then the sensor is in a fault state, which is a third type of fault, i.e., a failure fault.

[0053] Step S124: If the sampling temperature is less than the second preset temperature and the duration is greater than the fourth preset duration, determine that the motor is detected as the third type of fault state.

[0054] When the sampling temperature T remains below the preset second preset temperature T min If the duration t of the temperature being below the first preset temperature exceeds the fourth preset duration t4, then the sensor is also classified as a third type of fault, i.e., a failure fault.

[0055] Wherein, the second preset temperature is lower than the first preset temperature, and the second preset voltage is lower than the first preset voltage.

[0056] In a specific example, the microcontroller unit of the motor controller samples the voltage U of the NTC sensor at a fixed period, such as 10 milliseconds. Assuming the sensor operates normally within a voltage range of 0-200°C, U might be set... h For the voltage value corresponding to -10°C, U L This corresponds to the voltage value at 210°C. T max It can be set to 180°C, T min The temperature is set to -5°C. Time parameters t1 to t4 can be set according to the system's anti-interference requirements; for example, t1 can be 100 milliseconds. Those skilled in the art will understand that the above voltage, temperature, and time thresholds are merely examples and can be adaptively adjusted according to different sensor models, circuit designs, and application scenarios. The order of judgments in the diagnostic logic can also be adjusted; for example, multiple judgments can be executed in parallel.

[0057] Furthermore, detecting the fault status of the NTC sensor includes, but is not limited to, the methods described above. Additionally, it can improve detection accuracy by detecting whether the temperature change trend conforms to the basic laws of motor thermal dynamics. All these methods can achieve the higher-level function of detecting sensor failure. Therefore, step S12 also includes the following steps: Step S125: If the temperature change rate is greater than the first preset change rate and the number of consecutive occurrences is greater than the first preset number of occurrences, the motor is determined to be in a fourth type of fault state.

[0058] During motor operation, a calibrated sampling interval dt is established. Multiple sampled temperatures are collected within this sampling interval. The change in temperature dT is obtained by subtracting the lowest temperature from the highest temperature among the sampled temperatures. The rate of temperature change |dT / dt| is then calculated. When the rate of temperature change is greater than a first preset rate of change ΔT, the change is considered complete. max If the rate of change exceeds the first preset rate of change multiple times (e.g., n times), it indicates that the sensor is in a fault state, which is the fourth type of fault, also known as a jump fault.

[0059] Step S126: If the temperature change rate is less than the second preset change rate and the duration is greater than the fifth preset duration, determine that the motor is detected as a fifth type of fault state.

[0060] When the rate of temperature change is lower than the second preset rate of change △T min If the duration t of the change rate being lower than the second preset rate exceeds the fifth preset duration t5, then the sensor is in a fault state, which is the fifth type of fault, namely, a stuck fault.

[0061] Further, please refer to Figure 3 , Figure 3 This is a flowchart illustrating the third embodiment of the limp-riding control method of the present invention. The operating parameters include input voltage, input current, motor speed, and motor torque. Step S20 includes: Step S21: Determine the input power of the motor based on the input voltage and input current.

[0062] Calculate the operating heat Q generated by the motor during operation. g According to the law of conservation of energy, the heat generated by the motor mainly comes from its internal losses. In practice, the input power P of the motor can be calculated based on the collected real-time motor data. in The input power P of the motor in It can be obtained by multiplying the input voltage U1 and the input current I1 of the motor, i.e., P in =U1 I1.

[0063] Step S22: Determine the motor efficiency based on the motor speed and the motor torque.

[0064] Motor efficiency η can be determined based on the current motor speed n and torque T. q Obtained by querying a pre-calibrated efficiency MAP.

[0065] Step S23: Determine the operating heat based on the input power and the motor efficiency.

[0066] Power loss P of the motor loss This is the difference between the input power and the output power, and the output power can be calculated from the motor speed and motor torque. Since almost all the power loss during motor operation is converted into heat energy, assuming the sampling time is dt, the power loss P... loss It can be determined based on the following formula: .

[0067] Among them, P loss P represents power loss, η represents motor efficiency, and P represents power loss. in This refers to the input power.

[0068] The operating heat satisfies the following relationship: .

[0069] Among them, Q g The heat generated during operation is represented by dt, which is the sampling time.

[0070] More generally, heat Q g The purpose of the calculation is to quantify the heat generation rate or heat output of the motor during operation. It can also be achieved through other equivalent methods, such as directly calculating the losses of each part through the motor loss model (such as the copper loss and iron loss formulas) and summing them, and then multiplying by time to obtain the total heat output.

[0071] Further, please refer to Figure 4 The physical parameters include the heat transfer area, heat transfer path thickness, thermal conductivity, and convective heat transfer coefficient of the motor. Figure 4 This is a flowchart illustrating the fourth embodiment of the limp control method of the present invention. Step S30 includes: Step S31: Determine the first sub-heat dissipation of the motor based on the heat transfer area, heat transfer path thickness, and thermal conductivity coefficient.

[0072] Calculate the heat Q lost by the motor to the outside world. L Motor heat dissipation is a complex process, mainly including heat conduction, convection and radiation, and cooling medium heat dissipation.

[0073] As one implementation method, heat dissipation Q LIt consists of multiple sub-heat dissipation quantities. The first sub-heat dissipation quantity, Q1, is the heat transferred from the inside of the motor to the outer surface of the bridge housing or gearbox housing in contact with it through thermal conduction. Its calculation conforms to Fourier's law and specifically satisfies the following relationship: Q1=(k A ΔT) / d; Where k is the thermal conductivity coefficient of the contact material, A is the effective heat transfer area, ΔT is the temperature difference between the inside of the motor and the surface of the casing, and d is the thickness of the heat transfer path, with d being the average value.

[0074] The thermal conductivity coefficient, heat transfer area, and heat transfer path thickness can all be obtained from the motor's factory parameters or through actual measurements and calibrated within the system. The difference can be obtained by calculating the actual temperature and comparing it with the temperature data collected by a temperature sensor located on the outer casing surface.

[0075] Step S32: Determine the second sub-heat dissipation of the motor based on the heat transfer area and the convective heat transfer coefficient.

[0076] The second heat dissipation Q2 is the heat exchanged between the outer surface of the motor housing and the external environment through convection and radiation. It conforms to a comprehensive expression of Newton's law of cooling and Stefan-Boltzmann's law, specifically satisfying the following relationship: Q2=h A (T s -T amb )+ε σ A (T s 4 -T amb 4 ); Where h is the convective heat transfer coefficient, A is the heat transfer area, and T is the heat transfer coefficient. s T represents the outer surface temperature of the casing. amb ε is the ambient temperature, ε is the emissivity of the outer shell surface, and σ is the Stefan-Boltzmann constant.

[0077] Step S33: Determine the heat dissipation amount based on the first sub-heat dissipation amount and the second sub-heat dissipation amount.

[0078] Furthermore, as a preferred detailed embodiment, for motors that are partially associated with or have a built-in radiator in the refrigeration system, step S33 further includes: Step S331: Determine the third sub-heat dissipation based on the heat dissipation power of the radiator. The heat dissipation power is determined by the temperature difference between the inlet and outlet of the radiator and the specific heat capacity and density of the cooling medium.

[0079] The third heat dissipation, Q3, is the heat dissipated through the circulating cooling medium (such as water or oil) or radiator in the cooling system, and conforms to the heat capacity formula, specifically satisfying the following relationship: Q3=c1 ρ V ΔT c ; Where c1 is the specific heat capacity of the cooling medium, ρ is the density of the cooling medium, V is the volume of cooling medium flowing through the motor cooling channel per unit time, and ΔT c This refers to the temperature difference between the inlet and outlet of the cooling medium in the motor cooling channel.

[0080] Step S332: Determine the heat dissipation amount based on the first sub-heat dissipation amount, the second sub-heat dissipation amount, and the third sub-heat dissipation amount.

[0081] Therefore, within one sampling period dt, the total heat dissipated by the motor satisfies the following relationship: ; Those skilled in the art will understand that the above calculation is a relatively refined process. In other preferred embodiments, the above calculation process can be simplified. For example, only the most important heat dissipation path can be considered. For example, under the cooling effect of the cooling system, the third sub-heat dissipation Q3 is mainly calculated, while the influence of the first sub-heat dissipation Q1 and the second sub-heat dissipation Q2 is reflected by a correction coefficient.

[0082] Further, please refer to Figure 5 , Figure 5 This is a flowchart illustrating the fifth embodiment of the limp control method of the present invention. Step S50 includes: Step S51: If the actual temperature is less than or equal to the safe temperature threshold, the rated power of the motor shall be used as the operating power; The actual temperature T1 of the motor is calculated based on the heat balance. A calculation period or time threshold t6 is set, during which the net heat absorbed by the motor Q4 equals the operating heat Q. g With heat dissipation Q L The difference, i.e., Q4 = Q g -Q L .

[0083] This net heat absorption will cause a change in the overall temperature of the motor. The actual temperature T1 of the motor at the end of this time period can be calculated using the temperature rise formula, which specifically satisfies the following formula: β; Where c is the equivalent specific heat capacity of the motor, m is the mass of the motor, T0 is the temperature last collected before the NTC sensor fault was determined, and β is the correction coefficient.

[0084] Considering the errors that may occur during model data acquisition, a correction coefficient β can be introduced to calibrate the calculation results. β can be learned from historical data. For example, in one implementation, β can be set as the ratio of the average measured temperature to the average temperature calculated by the model during the same period, within a short period before the NTC sensor fails.

[0085] In this embodiment, the actual temperature is converted into specific actuator actions to achieve graded overheat protection and limp control.

[0086] Specifically, based on the motor's insulation class, material properties, and heat dissipation capacity, two key temperature thresholds are set: a safe temperature threshold representing the upper limit of temperature safety, denoted as T. a And the warning temperature threshold T, which represents the upper limit of temperature danger. b .

[0087] Among them, T a <T b The control strategy is as follows: when the actual temperature T1 is lower than T... a When the motor temperature is considered to be within a safe range, no additional limit is required on the motor output power, or the rated power value of the motor can be used as the operating power of the motor to ensure the maximum output of the motor and the normal operation of the vehicle.

[0088] Step S52: If the actual temperature is greater than the safe temperature threshold and less than or equal to the warning temperature threshold, determine the operating power based on the actual temperature.

[0089] When the actual temperature T1 is at T a and T b When the motor temperature has risen to a level requiring attention and there is a risk of overheating, the motor output should be limited by multiplying the rated power value of the motor by a coefficient 'a'. Due to the power limitation, the vehicle's performance decreases, entering a limp state, but it can still maintain traction.

[0090] Step S53: If the actual temperature is greater than the warning temperature threshold, adjust the operating power of the motor to 0.

[0091] When the actual temperature T1 exceeds T b If the motor temperature is deemed to have reached a dangerous level, the motor output power is immediately reduced to zero, forcing the vehicle to stop to protect the motor. The actual temperature T1 will then drop below T1 through heat dissipation. a Afterwards, the system can restore the motor to operate within the limp power limit and send a "limp" prompt message to the driver via the vehicle's dashboard.

[0092] Further, step S52 includes: Step S521: Determine the adjustment coefficient based on the actual temperature, wherein the adjustment coefficient is proportional to the actual temperature.

[0093] Step S522: Determine the operating power based on the rated power and the adjustment coefficient.

[0094] The coefficient 'a' is a derating factor greater than 0 and less than 1, and its specific value can be set based on the actual temperature. For example, it can be determined by pre-storing a mapping table and looking up the corresponding coefficient 'a' based on the actual temperature. Alternatively, it can be determined by comprehensively calibrating based on the vehicle's minimum power requirements during limp driving (such as maintaining a minimum stable speed while climbing an incline) and the rate of temperature rise. The purpose is to reduce heat generation by actively reducing power when the temperature is high, thereby preventing the temperature from rising further rapidly and giving the vehicle more time to reach a repair shop.

[0095] More generally, the core idea of ​​dynamic regulation is to implement forward-looking, gradual power limiting based on predicted temperature values. This is not limited to strict multiplicative power limits. For example, a dynamic power limit can be calculated in real-time using proportional or proportional-integral control algorithms based on the difference between the actual temperature and safe / warning temperature thresholds. Alternatively, after entering limp-mode, the power limit can be dynamically adjusted over time or based on remaining driving distance requirements.

[0096] Furthermore, after step S53, the following steps are also included: Step S54: Wait for a preset cooling time, and determine the actual temperature based on the preset cooling time.

[0097] Step S55: If the actual temperature is less than or equal to the safe temperature threshold, the rated power of the motor shall be used as the operating power.

[0098] If the actual motor temperature reaches the warning temperature threshold, a preset cooling time is established. After this preset cooling time, all data are collected again and the actual motor temperature is recalculated to determine whether the motor meets the conditions for vehicle restart after the preset cooling time. This avoids excessive waiting time and improves the user experience.

[0099] In a preferred embodiment, after an NTC sensor failure, the amount of heat Q that the motor can safely absorb under the current condition is calculated in real time using a temperature rise formula based on the actual temperature and the safe temperature threshold. x Set a heat safety threshold Q. y When the calculated absorbable heat Q x Greater than the threshold Q yAt that time, it was believed that the motor still had sufficient capacity to absorb the heat generated during operation, the risk was low, and the motor could operate at normal or higher power levels.

[0100] When the absorbable heat Q x Less than or equal to the threshold Q y When the motor's heat capacity approaches saturation, the risk of overheating increases significantly. At this point, the system sets a target time threshold t7, which can be estimated as the time required for the vehicle to travel to the nearest service station at a safe speed. The goal is to control the motor's heat generation within this time period t7, ensuring that the additional heat generated does not cause the motor temperature to exceed the dangerous upper limit T. b .

[0101] To simplify calculations and allow for a safety margin, the beneficial effects of heat dissipation can be temporarily ignored at this stage. Based on this, the amount of heat dissipation that the motor can still generate in the remaining time t7 can be calculated, and then the average power loss limit P1 can be derived.

[0102] Specifically, the heat safety threshold Q y It can be set to an absolute value based on engineering experience, for example, the heat required for a temperature rise of 5-10°C. If Q... x Less than or equal to Q y Then calculate the allowable average power loss P1=Q x / t7.

[0103] The principle behind this design is to quantify the temperature rise of the motor before it reaches the maintenance station as a limited "heat budget" and control the consumption rate of the "heat budget" by limiting the power loss.

[0104] Understandably, the time threshold t7 is not limited to a fixed value; it can be dynamically estimated based on the vehicle's current location, navigation information, and real-time traffic conditions. Thermal safety threshold Q y It can also be designed as a dynamic value that changes with ambient temperature or coolant temperature.

[0105] In addition, to solve the above problems, the present invention also proposes a computer-readable storage medium storing a limp control program, which, when executed by a processor, implements the steps of the limp control method as described above.

[0106] Computer-readable storage media may take the form of any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may, for example, include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0107] In addition to the methods and devices described above, embodiments of this application may also be computer program products, which include computer program information that, when run by a processor, causes the processor to execute steps in a limp control method according to various embodiments of this application.

[0108] Computer program products can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0109] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A limp control method, characterized in that, The limp control method includes: The motor detection device is determined to be in a faulty state based on its detection parameters. In the case of the aforementioned fault state, the operating heat of the motor is determined based on the motor's operating parameters; Based on the physical parameters of the motor, determine the heat dissipation of the motor; The actual temperature of the motor is determined based on the operating heat and the heat dissipation. The operating power of the motor is dynamically adjusted according to the actual temperature to enable the motor to operate in a limp-mode.

2. The limp control method as described in claim 1, characterized in that, Determining whether the motor detection device is in a faulty state based on its detection parameters includes: The detection parameters of the motor detection device are used to determine whether the detection parameters of the motor detection device are within the range of a preset threshold. When the detection parameter is within the range of the preset threshold, obtain the duration and / or number of times the detection parameter is within the preset threshold; If the duration exceeds a preset duration and / or the number of occurrences exceeds a preset number, the motor detection device is determined to be in a fault state.

3. The limp control method as described in claim 2, characterized in that, The detection parameters include sampling voltage or sampling temperature; If the duration exceeds a preset duration and / or the number of occurrences exceeds a preset number, the motor detection component is determined to be in a fault state, including: If the sampling voltage is greater than the first preset voltage and the duration is greater than the first preset duration, the motor is determined to be in a first type of fault state. If the sampling voltage is less than the second preset voltage and the duration is greater than the second preset duration, the motor is determined to be in a second type of fault state. If the sampling temperature is greater than the first preset temperature and the duration is greater than the third preset duration, the motor detection is determined to be a third type of fault state. If the sampling temperature is lower than the second preset temperature and the duration is greater than the fourth preset duration, the motor is determined to be in the third type of fault state. Wherein, the second preset temperature is lower than the first preset temperature, and the second preset voltage is lower than the first preset voltage.

4. The limp control method as described in claim 3, characterized in that, The detection parameters also include the rate of temperature change determined based on the sampling temperature; Determining the motor detection device to be in a fault state when the duration exceeds a preset duration and / or the number of occurrences exceeds a preset number further includes: If the temperature change rate is greater than a first preset change rate and the number of consecutive occurrences is greater than a first preset number of occurrences, the motor detection is determined to be a fourth type of fault state. If the temperature change rate is less than the second preset change rate and the duration is greater than the fifth preset duration, the motor is determined to be in a fifth type of fault state.

5. The limp control method as described in claim 1, characterized in that, The operating parameters include input voltage, input current, motor speed, and motor torque; The operating heat of the motor is determined based on its operating parameters, including: The input power of the motor is determined based on the input voltage and input current; The motor efficiency is determined based on the motor speed and the motor torque; The operating heat is determined based on the input power and the motor efficiency.

6. The limp control method as described in claim 1, characterized in that, The physical parameters include the heat transfer area, heat transfer path thickness, thermal conductivity, and convective heat transfer coefficient of the motor. Based on the physical parameters of the motor, the heat dissipation of the motor is determined, including: The first sub-heat dissipation of the motor is determined based on the heat transfer area, heat transfer path thickness, and thermal conductivity coefficient. The second sub-heat dissipation of the motor is determined based on the heat transfer area and the convective heat transfer coefficient. The heat dissipation is determined based on the first sub-heat dissipation and the second sub-heat dissipation.

7. The limp control method as described in claim 6, characterized in that, The motor also includes a radiator; Determining the heat dissipation based on the first sub-heat dissipation and the second sub-heat dissipation includes: The third sub-heat dissipation is determined based on the heat dissipation power of the radiator. The heat dissipation power is determined by the temperature difference between the inlet and outlet of the radiator and the specific heat capacity and density of the cooling medium. The heat dissipation is determined based on the first sub-heat dissipation, the second sub-heat dissipation, and the third sub-heat dissipation.

8. The limp control method as described in claim 1, characterized in that, Dynamically adjusting the operating power of the motor according to the actual temperature to enable limp-out operation of the motor includes: When the actual temperature is less than or equal to the safe temperature threshold, the rated power of the motor shall be used as the operating power. If the actual temperature is greater than the safe temperature threshold but less than or equal to the warning temperature threshold, the operating power is determined based on the actual temperature. If the actual temperature is greater than the warning temperature threshold, the operating power of the motor will be adjusted to 0.

9. The limp control method as described in claim 8, characterized in that, Determining the operating power based on the actual temperature includes: An adjustment coefficient is determined based on the actual temperature, wherein the adjustment coefficient is proportional to the actual temperature; The operating power is determined based on the rated power and the adjustment coefficient.

10. The limp control method as described in claim 8, characterized in that, After adjusting the operating power of the motor to 0, the method further includes: Wait for a preset cooling time, and determine the actual temperature based on the preset cooling time; When the actual temperature is less than or equal to the safe temperature threshold, the rated power of the motor shall be used as the operating power.

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