Sensorless motor stator temperature protection method, device and equipment

Abstract

The invention provides a sensorless motor stator temperature protection method, device and equipment, and relates to the technical field of motor control, and the protection method comprises the steps: obtaining the current voltage, current and rotating speed of a motor when the motor in a motor control system is in a running state, determining a corresponding temperature rise coefficient and a heat balance temperature according to the current voltage, the current current and the current rotating speed; obtaining a current estimated temperature according to the current voltage, the current current and the current rotating speed; determining a current predicted temperature according to the current estimated temperature, the heat balance temperature, the last estimated temperature and the corresponding temperature rise coefficient; and comparing the current predicted temperature with a preset protection threshold value, and performing temperature protection control on the motor according to a comparison result. A temperature sensor does not need to be installed in the motor, so that the installation difficulty and cost are reduced, the reliability and durability of the system are improved, and the risk that the sensor breaks down or is damaged is avoided.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and more specifically, to a sensorless motor stator temperature protection method, device, and equipment. Background Technology

[0002] Traditional motor temperature protection methods typically involve installing temperature sensors inside the motor to monitor temperature changes and using the data from these sensors to determine whether to trigger the temperature protection mechanism. However, this method has several limitations: First, the installation process for temperature sensors is complex and costly, increasing the economic burden of motor manufacturing and maintenance. Second, the sensors themselves are prone to failure or damage; failure can lead to inaccurate or non-monitoring of temperature data, thus reducing the reliability and durability of the entire motor system. Furthermore, traditional methods often rely solely on running time or current magnitude for simple temperature accumulation, which is inaccurate and makes it difficult to achieve precise, real-time monitoring and effective protection of the motor stator resistance temperature. It also fails to respond promptly to temperature changes to prevent overheating damage, thus impacting the motor's lifespan and operational stability. Summary of the Invention

[0003] The problem solved by this invention is one or more of the aforementioned related technical problems.

[0004] To address the above problems, the present invention provides a sensorless motor stator temperature protection method, device, and equipment.

[0005] In a first aspect, the present invention provides a sensorless motor stator temperature protection method, applied to a motor control system, the sensorless motor stator temperature protection method comprising: When the motor in the motor control system is running, the current voltage, current current and current speed of the motor are acquired, and the corresponding temperature rise coefficient and thermal equilibrium temperature are determined based on the current voltage, current current and current speed. The current estimated temperature is obtained based on the current voltage, the current current, and the current rotation speed; The current predicted temperature is determined based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient. The current predicted temperature is compared with a preset protection threshold, and the motor is subjected to temperature protection control based on the comparison result.

[0006] Optionally, obtaining the current estimated temperature based on the current voltage, the current current, and the current rotational speed includes: Obtain the previously estimated temperature; The current estimated temperature is obtained based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed.

[0007] Optionally, obtaining the current estimated temperature based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed includes: The current estimated temperature is obtained using Equation 1, based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed. Wherein, Equation 1 is: ; in, For the current estimated temperature, The current voltage, For the current, Due to environmental temperature differences, For motor operating efficiency, The current rotational speed, For heat capacity data, This relates the motor's heat dissipation capacity to the current rotational speed. The previous estimated temperature.

[0008] Optionally, determining the current predicted temperature based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient includes: The difference data is determined based on the current estimated temperature and the thermal equilibrium temperature; The current predicted temperature is obtained based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient.

[0009] Optionally, obtaining the current predicted temperature based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient includes: The current predicted temperature is obtained using Equation 2, based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient. Wherein, the second formula is: ; Where T is the current predicted temperature. The previous estimated temperature, For adjustment coefficients, The temperature rise coefficient is... The difference data is referred to here.

[0010] Optionally, obtaining the initial stator resistance temperature includes: When the motor is in the startup phase, the current and voltage information of the motor are acquired; Based on a preset stator identification method, the initial stator resistance temperature is determined according to the current information and the voltage information.

[0011] Optionally, the preset protection threshold includes a first threshold and a second threshold, and the step of performing temperature protection control on the motor based on the comparison result includes: When the current predicted temperature is greater than or equal to the first threshold and less than the second threshold, the speed of the motor is reduced. When the current predicted temperature is greater than or equal to the second threshold, the motor is controlled to stop running, and the motor restart function is locked.

[0012] Secondly, the present invention provides a sensorless motor stator temperature protection device, applied to a motor control system, the sensorless motor stator temperature protection device comprising: The data acquisition unit acquires the current voltage, current, and current speed of the motor when the motor in the motor control system is running, and determines the corresponding temperature rise coefficient and thermal equilibrium temperature based on the current voltage, current, and current speed. The processing unit is configured to obtain the current estimated temperature based on the current voltage, the current current, and the current rotational speed; determine the current predicted temperature based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient; compare the current predicted temperature with a preset protection threshold, and perform temperature protection control on the motor based on the comparison result.

[0013] Thirdly, the present invention provides a sensorless motor stator temperature protection device, including a memory and a processor; the memory is used to store a computer program; the processor is used to implement the sensorless motor stator temperature protection method as described in the first aspect when the computer program is executed.

[0014] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the sensorless motor stator temperature protection method as described in the first aspect.

[0015] The beneficial effects of the sensorless motor stator temperature protection method, device, and equipment of the present invention are: This sensorless motor stator temperature protection method mainly relies on key parameters during motor operation to achieve real-time monitoring and protection of stator temperature.

[0016] During motor operation, the motor voltage, current, and speed are acquired over a certain period. The acquired voltage, current, and speed are then used to determine the corresponding temperature rise coefficient and thermal equilibrium temperature. This process can be achieved by consulting a pre-established two-dimensional table (usually obtained through experimental calibration).

[0017] Based on the current voltage, current, and speed, the estimated temperature is calculated using a thermal model. Similarly, the estimated temperature from the previous cycle can be obtained using a similar method. Then, based on the current estimated temperature, thermal equilibrium temperature, the previous estimated temperature, and the temperature rise coefficient, the predicted temperature is calculated. If the predicted temperature reaches or exceeds a preset protection threshold, the temperature protection mechanism is triggered, and corresponding protective measures are taken for the motor.

[0018] Therefore, this invention eliminates the need for internal temperature sensors in the motor, reducing installation difficulty and cost, improving system reliability and durability, and avoiding the risk of sensor malfunction or damage. This invention can monitor the stator temperature of the motor in real time, respond quickly to temperature changes, and take timely protective measures to effectively prevent motor damage due to overheating, thereby extending the motor's service life. Furthermore, by comprehensively considering multiple operating parameters (voltage, current, speed) as well as the temperature rise coefficient and thermal equilibrium temperature, this invention can more accurately predict the stator temperature, significantly improving the accuracy and effectiveness of temperature protection. Simultaneously, it is applicable to motor operation under various working conditions and loads, and can dynamically adjust the protection strategy according to the actual operating status, ensuring safe and stable motor operation in different application scenarios. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of a sensorless motor stator temperature protection method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a set of calibration data according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a sensorless motor stator temperature protection device according to an embodiment of the present invention. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0021] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0022] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0023] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0024] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0025] To address the problems existing in the aforementioned related technologies, embodiments of the present invention provide a sensorless motor stator temperature protection method, device, system, and storage medium.

[0026] like Figure 1 As shown in the figure, an embodiment of the present invention provides a sensorless motor stator temperature protection method, which is applied to a motor control system. The sensorless motor stator temperature protection method includes: Step S100: When the motor in the motor control system is running, the current voltage, current current and current speed of the motor are obtained, and the corresponding temperature rise coefficient and thermal equilibrium temperature are determined based on the current voltage, current current and current speed.

[0027] Specifically, when the motor is running, three key operating parameters are acquired in real time: current voltage, current current, and current speed. These parameters directly reflect the motor's operating status and have a direct impact on temperature changes. Voltage, current, and speed directly affect the motor's heat generation. For example, an increase in current usually leads to an increase in copper losses in the motor windings, thus generating more heat; changes in speed affect the motor's mechanical losses and cooling effect.

[0028] Based on the collected current voltage, current, and speed, the corresponding temperature rise coefficient and thermal equilibrium temperature will be queried or calculated. For example, the corresponding temperature rise coefficient and thermal equilibrium temperature can be obtained by consulting two two-dimensional tables: the "Current and Speed ​​- Temperature Rise Coefficient Table" and the "Current and Speed ​​- Thermal Equilibrium Temperature Table." The voltage values ​​are mainly used for power compensation calculations when the voltage fluctuates; under normal conditions, they do not affect the calculation results. The data in these two-dimensional tables needs to be obtained in advance through calibration experiments on a dynamometer under different power and speed adjustments to determine the operating temperature changes.

[0029] The temperature rise coefficient reflects the rate of temperature change of the motor per unit time under the current operating conditions, while the thermal equilibrium temperature refers to the temperature at which the motor temperature reaches a stable state under continuous operating conditions.

[0030] These data can be obtained from a database based on prior experiments or calculated in real time using an algorithmic model. The database typically contains temperature rise coefficients and thermal equilibrium temperatures under different operating conditions, while the algorithmic model can make real-time predictions based on the motor's thermal characteristics and operating parameters.

[0031] By acquiring real-time voltage, current, and speed data of the motor and combining this data with the temperature rise coefficient and thermal equilibrium temperature, the real-time temperature changes of the motor can be predicted more accurately, thereby enhancing the reliability of the temperature monitoring system. This accurate temperature prediction helps to promptly detect overheating risks and take preventative measures to avoid motor damage and extend its service life. Simultaneously, understanding the motor's real-time temperature status is crucial for optimizing control strategies, such as adjusting the PWM duty cycle or speed to achieve more efficient and stable operation. Accurate temperature monitoring and prediction can effectively prevent the motor from operating under overheated conditions, thus improving the safety and stability of the entire system.

[0032] Step S200: Obtain the current estimated temperature based on the current voltage, the current current, and the current rotation speed.

[0033] Specifically, a pre-established thermal model is used to estimate the motor temperature based on voltage, current, and speed. This model may be based on physical formulas such as Joule's law (the heat generated by an electric current passing through a conductor is proportional to the square of the current, the resistance, and the time), combined with the motor's thermal characteristics and heat dissipation conditions.

[0034] Based on the theoretical values ​​calculated by the model, combined with the actual heat dissipation of the motor and the ambient temperature, the current estimated temperature of the motor is calculated. This step may also involve analyzing the motor's historical operating data and heat dissipation efficiency. To improve the accuracy of the estimate, the model may be calibrated based on the actual operating data of the motor to adapt to the actual working conditions of the motor.

[0035] By combining real-time operating parameters of the motor with a thermal model, its current temperature can be predicted more accurately, thereby improving the reliability of the temperature monitoring system. This accurate temperature estimation helps to detect overheating risks in a timely manner and take preventive measures, such as adjusting the workload or enhancing heat dissipation, to prevent motor damage. Knowing the motor's real-time temperature status is crucial for optimizing control strategies; more efficient operation can be achieved by adjusting the PWM duty cycle or speed. Furthermore, avoiding operation of the motor in an overheated state reduces thermal stress damage to materials, extends motor life, improves the safety and stability of the entire system, and reduces the frequency of unexpected downtime and maintenance.

[0036] Step S300: Determine the current predicted temperature based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient.

[0037] Specifically, the current temperature is calculated using the motor's real-time operating parameters (voltage, current, and speed) and a thermal model. Thermal equilibrium temperature: The stable temperature reached by the motor after a period of continuous operation, reflecting the motor's long-term thermal state. Previous estimated temperature: The estimated motor temperature calculated at the previous time point, used to track temperature change trends. Temperature rise coefficient: Represents the proportion of temperature change of the motor per unit time; it changes dynamically according to the motor's load and environmental conditions.

[0038] Using these collected data points, a temperature prediction model or formula is applied to estimate the current predicted temperature of the motor. This model or formula may employ linear regression, time series analysis, or other mathematical models, taking the current estimated temperature, thermal equilibrium temperature, previous estimated temperature, and temperature rise coefficient as input variables.

[0039] By integrating multiple temperature-related parameters and temperature rise coefficients, this prediction method is more accurate than single-parameter estimation, thus improving system reliability. Considering historical temperatures and thermal equilibrium temperatures allows the system to adapt to the motor's thermal behavior under different loads and environmental conditions, enabling flexible temperature management. Accurate prediction helps detect overheating risks early, allowing the system to take timely measures, such as reducing speed or adjusting load, to prevent motor damage. Precise control of the motor's operating temperature optimizes its performance and efficiency, avoiding performance degradation caused by extreme temperature operation. Furthermore, accurate temperature prediction and timely protective measures can reduce failures and downtime caused by overheating, lower maintenance costs, and improve production efficiency.

[0040] In summary, step S300 predicts the current temperature of the motor by comprehensively analyzing various temperature-related parameters. This not only improves the accuracy of temperature monitoring but also enhances the system's adaptability and preventative capabilities, helping to optimize motor performance and reduce maintenance costs.

[0041] Step S400: Compare the current predicted temperature with the preset protection threshold, and perform temperature protection control on the motor based on the comparison result.

[0042] Specifically, the current predicted temperature is first obtained using a temperature prediction model. Based on the motor's design parameters and safe operating requirements, one or more protection thresholds are set. These thresholds represent the upper limits of the temperature; exceeding these limits may damage the motor.

[0043] The current predicted temperature is compared with a preset protection threshold. This is typically a real-time monitoring process to ensure the motor operates within a safe temperature range.

[0044] If the current predicted temperature is below the protection threshold, the motor is considered to be operating in a safe state and no special measures are required.

[0045] If the current predicted temperature reaches or exceeds the protection threshold, corresponding protective measures will be triggered. For example, the motor's power output may be reduced, the speed may be decreased, the cooling system may be activated, or in severe cases, the motor may be stopped to prevent overheating damage.

[0046] Real-time temperature monitoring and comparison allows for timely identification of overheating risks, enabling measures to be taken to prevent motor damage due to overheating and improving system safety and reliability. This not only reduces thermal stress on motor materials from high temperatures, extending motor lifespan, but also reduces downtime and failures caused by overheating, thereby reducing maintenance costs and increasing production efficiency. Simultaneously, adjusting motor operating parameters to maintain them within a safe temperature range optimizes motor performance and efficiency. Furthermore, automatic adjustments based on different loads and environmental conditions ensure safe motor operation under various operating conditions.

[0047] In this embodiment, the sensorless motor stator temperature protection method mainly relies on key parameters during motor operation to achieve real-time monitoring and protection of stator temperature.

[0048] During motor operation, the motor voltage, current, and speed are acquired over a certain period. The acquired voltage, current, and speed are then used to determine the corresponding temperature rise coefficient and thermal equilibrium temperature. This process can be achieved by consulting a pre-established two-dimensional table (usually obtained through experimental calibration).

[0049] Based on the current voltage, current, and speed, the estimated temperature is calculated using a thermal model. Similarly, the estimated temperature from the previous cycle can be obtained using a similar method. Then, based on the current estimated temperature, thermal equilibrium temperature, the previous estimated temperature, and the temperature rise coefficient, the predicted temperature is calculated. If the predicted temperature reaches or exceeds a preset protection threshold, the temperature protection mechanism is triggered, and corresponding protective measures are taken for the motor.

[0050] Therefore, this invention eliminates the need for internal temperature sensors in the motor, reducing installation difficulty and cost, improving system reliability and durability, and avoiding the risk of sensor malfunction or damage. This invention can monitor the stator temperature of the motor in real time, respond quickly to temperature changes, and take timely protective measures to effectively prevent motor damage due to overheating, thereby extending the motor's service life. Furthermore, by comprehensively considering multiple operating parameters (voltage, current, speed) as well as the temperature rise coefficient and thermal equilibrium temperature, this invention can more accurately predict the stator temperature, significantly improving the accuracy and effectiveness of temperature protection. Simultaneously, it is applicable to motor operation under various working conditions and loads, and can dynamically adjust the protection strategy according to the actual operating status, ensuring safe and stable motor operation in different application scenarios.

[0051] Optionally, obtaining the current estimated temperature based on the current voltage, the current current, and the current rotational speed includes: Obtain the previously estimated temperature; The current estimated temperature is obtained based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed.

[0052] Specifically, when the stator resistance temperature is estimated for the first time, i.e., at the start of operation, the previous estimated temperature of the stator resistance is the initial stator resistance temperature. This initial stator resistance temperature can be the ambient temperature when the motor is not powered on, or the initial temperature when the motor has just started. During the motor startup phase, after obtaining the initial stator resistance through stator identification technology, the initial motor stator temperature can be obtained by looking up a calibrated stator resistance-temperature lookup table. Subsequent stator resistance temperature estimates during operation are based on the previous estimated temperature, combined with the corresponding current voltage, current, and current speed to obtain the current estimated temperature. For example, the heat generated and dissipated by the motor in the current operating state can be calculated using a thermal model of the motor, and then the current temperature can be estimated based on the heat balance principle. Alternatively, a pre-established lookup table can be used to find the corresponding temperature change based on the current voltage, current, and speed, and then combined with the previous estimated temperature (the stator resistance temperature) to obtain the current estimated temperature. This method enables real-time and dynamic monitoring of the stator temperature during motor operation, timely detection of temperature anomalies, and early implementation of protective measures to prevent overheating and damage to the motor. This, in turn, enhances the reliability and safety of motor operation and extends its service life.

[0053] Optionally, obtaining the current estimated temperature based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed includes: The current estimated temperature is obtained using Equation 1, based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed. Wherein, Equation 1 is: ; in, For the current estimated temperature, The current voltage, For the current, Due to environmental temperature differences, To output torque data, The current rotational speed, For heat capacity data, This relates the motor's heat dissipation capacity to the current rotational speed. The previous estimated temperature.

[0054] In some embodiments, for the real-time temperature prediction process of the stator resistance (temperature estimation process of the stator resistance), when the motor is running, the current voltage, current, and current speed are obtained. The average values ​​of voltage, current, and speed within a set time step (e.g., a time step of 10 seconds) can be obtained and used as input parameters. A two-dimensional table is then consulted to obtain the corresponding temperature rise coefficient and thermal equilibrium temperature. There are two two-dimensional tables: a current & speed-temperature rise coefficient table and a current & speed-thermal equilibrium temperature table (voltage values ​​are mainly used for power compensation calculations during voltage fluctuations and do not normally affect the calculation results). Obtaining the data from the two-dimensional tables requires prior temperature change calibration experiments under different power and speed adjustments on a dynamometer.

[0055] The derivation of the formula for estimating the temperature for calculating electronic resistance is as follows: (The derivation is explained using the initial estimated temperature). Based on the concept of lumped parameter thermal models, the overall heat capacity of the motor, including the heat dissipation components, can be set as follows: (Heat capacity data), the heat generated within the preset time is Without considering heat dissipation, then its temperature change The current temperature of the stator resistor is... T, where The current temperature. The initial stator resistance temperature.

[0056] For electric motors, their efficiency generally stabilizes after reaching a certain speed; that is, the motor's operating efficiency is set to a certain value. This refers to the ratio of output power to input power. Specifically, this can be recorded during dynamometer testing. The dynamometer obtains the input and output power values ​​and calculates the efficiency accordingly. For currently used motors, the efficiency is consistently around 80% under actual operating conditions. Subsequent temperature rise coefficients and thermal equilibrium temperature estimates are directly calculated based on the measured current, speed, and temperature values. The input power can be calculated from the bus voltage and current. The output power can be obtained from the input power and the motor operating efficiency. The ratio of output power to input power is given, but for simplicity, we can assume that... Then the heat dissipated by the motor at this time is ,Right now Under stable conditions, efficiency is directly proportional to the magnitude of voltage and current. Since the input voltage of a typical motor is stable, the magnitude of the current is the primary consideration. Furthermore, the actual heat accumulated by the motor needs to be considered in terms of heat dissipation. For motors equipped with cooling fan blades, the heat dissipation is mainly related to the motor speed and the ambient temperature difference. The higher the speed, the greater the temperature difference between the motor and the ambient temperature, and the greater the corresponding heat dissipation. Therefore, heat dissipation can be considered a variable related to motor speed and ambient temperature difference, denoted as... Furthermore, the ambient temperature difference generally has a positive correlation with heat dissipation capacity, and within a certain range, it can be considered a linear gain. Therefore, heat dissipation can also be written as... .

[0057] in, This indicates the relationship between heat dissipation capacity and motor speed v. The relationship between heat dissipation capacity and rotational speed / ambient temperature difference is a binary function, with both closely related to the final heat dissipation. According to measured data, the former (rotational speed) approximates a monotonically increasing relationship, similar to a power function with a constant less than 1. The latter (ambient temperature difference) has higher values ​​under high rotational speed and large temperature difference conditions, and lower values ​​under low rotational speed and small temperature difference conditions. It can be visualized as a diagonally tilted two-dimensional plane, and subsequent fitting will primarily rely on calibration data. The linear gain directly uses the ambient temperature difference as the gain coefficient, and the effect of rotational speed on heat dissipation is fitted based on calibration data. Furthermore, for... , These are used to represent different functional relationships, and there is no inheritance or transformation relationship between them here. Furthermore, since fluctuations in ambient temperature when the value is small have little impact on heat dissipation capacity, the ambient temperature is generally set to a fixed value, such as 25℃. During initial operation, the stator temperature is estimated based on the resistance identified by the stator resistance. Subsequently, the stator temperature change is estimated online, and the ambient temperature difference can be obtained by subtracting the estimated stator temperature (e.g., 25℃).

[0058] Next, the formula for motor temperature change can be further simplified as follows: ; ; ; ; in, The stator resistance identification algorithm is used to obtain the current, speed and overall heat capacity parameters of the motor. The parameters can be roughly extracted and characterized by the power calibration data. In order to simplify the temperature estimation process, it is desirable to use a lookup table method to obtain the temperature estimation parameters. The motor speed and bus current can be selected as the lookup table parameters, and the temperature-related quantities can be selected as the query targets (the temperature rise coefficient and thermal equilibrium temperature can be selected as the query target parameters later).

[0059] For the initial temperature estimation That is, the temperature data corresponding to the stator resistance obtained from stator identification is selected. However, for non-first-time temperature estimations, for The estimated temperature of the previous stator resistance was selected.

[0060] In some embodiments, during pre-calibration, it is necessary to obtain the current and speed data corresponding to each power point, as well as the corresponding temperature rise rate and thermal equilibrium temperature information. Based on this data, two two-dimensional tables are created, with the effective current value and speed as the horizontal and vertical axes respectively, and the temperature rise coefficient and thermal equilibrium temperature set as the query targets. Using a comprehensive thermal model of the motor, temperature change characteristics can be simulated, and the motor's thermal characteristics can be centrally represented as overall heat capacity, heat generation, and heat dissipation parameters. Generally, the higher the current and the lower the speed, the higher the temperature rise rate and thermal equilibrium temperature; conversely, the lower the current and the higher the speed, the lower the temperature rise rate and thermal equilibrium temperature. Figure 2 A set of calibration data is presented, with the horizontal axis representing time (in seconds) and the vertical axis representing motor stator temperature (in degrees Celsius). When the motor speed is fixed at 0.4 per unit, the controller bus current is applied using a dynamometer to reach 0.1, 0.2, 0.3, and 0.4 per unit, respectively. It can be observed that the motor stator temperature tends to stabilize after running for a period of time. The graph clearly shows that the rate of temperature rise and the final stable thermal equilibrium temperature of the motor stator differ at different current levels, reflecting the temperature change when heat generation and heat dissipation reach equilibrium.

[0061] After determining the current and rotational speed, obtain the corresponding temperature rise rate (the average slope of the middle part of each curve segment, i.e., the temperature rise coefficient) and the thermal equilibrium temperature (the temperature increases slightly after the slope decreases). This will generate two two-dimensional lookup tables with relevant data. Then, during operation, the temperature rise rate and target equilibrium temperature under normal conditions can be directly obtained based on the voltage, current, and rotational speed data.

[0062] It should be noted that pre-calibration refers to obtaining temperature characteristic data of the motor under different operating conditions through experiments before the motor is officially put into operation and temperature prediction is performed. Based on this data, a model or table is built so that temperature prediction and protection can be accurately performed in actual operation.

[0063] Specifically: On the dynamometer, the motor is set to run under different power and speed conditions.

[0064] Under each operating condition, monitor and record the temperature changes of the motor stator, including the rate of temperature rise and the final thermal equilibrium temperature reached.

[0065] Based on the collected data, two two-dimensional tables were created: one table uses current and rotational speed as the horizontal and vertical axes, with the temperature rise coefficient as the query target; the other table also uses current and rotational speed as the horizontal and vertical axes, with the thermal equilibrium temperature as the query target. These tables are used to quickly look up the corresponding temperature rise coefficient and thermal equilibrium temperature during actual operation.

[0066] The overall heat capacity (C) and efficiency (μ) of the motor were determined using experimental data. Heat capacity represents the motor's ability to absorb heat and cause temperature changes, while efficiency represents the motor's ability to convert input power into output power. The motor's heat dissipation characteristics were analyzed, and a model was established to model the relationship between heat dissipation, rotational speed, and ambient temperature difference.

[0067] Pre-calibration obtains temperature characteristic data of the motor under different operating conditions through experiments, and establishes a predictive model and lookup table. It provides the necessary parameters and data support for subsequent real-time temperature prediction, ensuring that the system can accurately estimate and protect against temperature changes.

[0068] Optionally, determining the current predicted temperature based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient includes: The difference data is determined based on the current estimated temperature and the thermal equilibrium temperature; The current predicted temperature is obtained based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient.

[0069] Specifically, the difference between the current estimated temperature and the thermal equilibrium temperature is calculated. This difference reflects the temperature gap between the current temperature and the state of thermal equilibrium. Then, this difference data is processed and analyzed in conjunction with the previous estimated temperature and the corresponding temperature rise coefficient. The temperature rise coefficient plays a crucial role here, reflecting the rate or trend of temperature change under specific conditions. By combining the difference data, the previous estimated temperature, and the temperature rise coefficient, the current predicted temperature can be obtained. This temperature value not only considers the current temperature state but also incorporates historical temperature information and temperature change trends, thus achieving accurate prediction of the motor stator temperature.

[0070] By combining the current estimated temperature, thermal equilibrium temperature, previous estimated temperature, and temperature rise coefficient, the actual temperature of the motor stator can be accurately predicted, improving monitoring accuracy. This method can dynamically reflect temperature change trends, effectively track rapid changes, and promptly detect anomalies. Based on accurate prediction, the system can provide early warnings, offering sufficient time to take protective measures to prevent motor overheating and damage, improving operational reliability and safety, and extending service life. It is applicable to different operating conditions and load conditions, and can dynamically adjust the prediction strategy according to the actual operating status, ensuring the safe and stable operation of the motor in various scenarios.

[0071] Optionally, obtaining the current predicted temperature based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient includes: The current predicted temperature is obtained using Equation 2, based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient. Wherein, the second formula is: ; Where T is the current predicted temperature. The previous estimated temperature, For adjustment coefficients, The temperature rise coefficient is... The difference data is referred to here.

[0072] Specifically, based on the difference between the target equilibrium temperature and the current estimated temperature This can compensate for the impact of heat dissipation caused by temperature difference, thereby improving estimation accuracy while ensuring ease of calculation.

[0073] Generally, when the estimated temperature (current estimated temperature) is lower than the thermal equilibrium temperature, the lower the estimated temperature (i.e., the smaller the difference between the current temperature and room temperature), the faster the heating rate needs to be, and positive temperature rise gain compensation will be performed. Conversely, when the estimated temperature (current estimated temperature) is higher than the thermal equilibrium temperature, it indicates that the motor is cooling down, and cooling gain compensation calculation will be performed based on the temperature difference. This allows for better handling of heating and cooling during long-term motor operation. The specific calculation formula is Equation 2. Wherein, This is the difference between the current estimated temperature and the thermal equilibrium temperature obtained from the table (the sign of the difference indicates the difference between heating and cooling). K is the adjustment coefficient, which defaults to 1 and can be modified appropriately to adjust the temperature rise estimation rate, used to fine-tune the trigger sensitivity of the temperature protection. The temperature rise coefficient is obtained by looking up a table.

[0074] When the current is high and the rotation speed is low, the corresponding thermal equilibrium temperature and temperature rise coefficient are relatively high (i.e., through...). and To fit the temperature changes caused by current and speed, the estimated temperature will rise rapidly. When the current is low and the speed is high, the corresponding thermal equilibrium temperature is low, and the estimated temperature will gradually decrease. Voltage U, motor efficiency μ, and overall heat capacity C are normally considered constants, and their effects are summarized in the two-dimensional tables of speed & current-thermal equilibrium temperature and speed & current-temperature rise coefficient during calibration. Ambient temperature difference... It primarily affects heat dissipation capacity, and indirectly affects temperature rise. This has been partially summarized. A large ambient temperature difference generally indicates a higher stator temperature, which corresponds to a temperature closer to thermal equilibrium. A smaller value indicates that the rate of temperature rise is slower due to stronger heat dissipation, while a larger value would result in a faster rate of temperature rise.

[0075] Optionally, obtaining the initial stator resistance temperature includes: When the motor is in the startup phase, the current and voltage information of the motor are acquired; Based on a preset stator identification method, the initial stator resistance temperature is determined according to the current information and the voltage information.

[0076] Specifically, during the motor startup phase, the motor's current and voltage information are monitored and collected in real time. This is because during startup, the motor's current and voltage are typically high and fluctuate dramatically, providing sufficient information to identify the stator resistance.

[0077] Based on a pre-defined stator identification algorithm or model, the stator resistance is determined using the collected current and voltage information. For example, the stator resistance can be calculated using Ohm's law. To carry out, among which, It is the stator resistance. I is voltage, and I is current. However, due to factors such as back electromotive force during motor startup, actual calculations may require more complex models to account for these effects. Alternatively, the stator resistance can be determined by adjusting the output PWM duty cycle using feedback. For example: Upon receiving the user's command to start the motor, the system first selects the MOSFET combination to be controlled based on the initial rotor position confirmed by the original drive prepositioning function.

[0078] The conducting phase current value of the motor is obtained through a current sampling circuit. These current values ​​will be used in subsequent current closed-loop control processing.

[0079] By combining the sampled current value, closed-loop current control is performed by controlling the output duty cycle of the PWM (Pulse Width Modulation) wave. PWM is a commonly used motor control technique; by adjusting the duty cycle of the PWM wave, the input voltage and current of the motor can be controlled, thereby achieving control over the motor's speed and torque.

[0080] During the adjustment phase, based on the error between the current value obtained by the sampling circuit and the set reference current value, the output PWM duty cycle is adjusted to bring the actual current value close to the set reference current value. The purpose of this phase is to ensure that the motor operates at the expected current to achieve precise speed or torque control.

[0081] During the stabilization phase, a fixed PWM duty cycle is maintained for 512 cycles. During this period, the average values ​​of the current and voltage collected are recorded. and and the PWM duty cycle at this time. The purpose of this stage is to ensure that the motor operates in a stable state so that more accurate parameter measurements and control can be performed.

[0082] This control process is performed twice, stabilizing the current at two set reference current values ​​each time. This allows for more comprehensive testing and adjustment of the motor's current response, ensuring stable operation under varying current conditions.

[0083] Finally, after completing the two-stage current closed-loop control process, According to the formula Calculate the resistance. Here. and The different PWM duty cycles in the two control processes and These are the average values ​​of voltage and current during the second control process. The calculated stator resistance is given.

[0084] An equivalent inverse pulse technique is introduced into the current closed-loop control process. By actively turning off the inverter's lower bridge output, the energy stored in the motor's inductance is used to activate the body diode of the switching device, forming a freewheeling circuit and introducing an equivalent voltage inverse pulse. Based on this, the stator resistance of high-voltage brushless DC motors can be measured, avoiding the problems of insufficient sampling window due to a small PWM duty cycle limit under high-voltage power supply conditions, or the risk of overcurrent. For the aforementioned formula, simply subtracting the set off time value from the duty cycle value yields the effective voltage conduction time value, making the compensation method simple.

[0085] Once the stator resistance is determined, the initial stator resistance temperature can be calculated based on the motor's thermal model and resistance value. This temperature typically refers to the actual temperature of the stator when the motor starts, which can be the ambient temperature or slightly higher.

[0086] By accurately acquiring the initial stator resistance temperature, we provide a reliable benchmark for motor temperature prediction, significantly improving the accuracy and reliability of the monitoring system. This capability enables the system to make accurate temperature predictions immediately upon motor startup, thereby enhancing its adaptability to different operating conditions, especially during the startup phase. Furthermore, accurate initial temperature information helps optimize motor startup control strategies, reducing current surges and thermal stress during startup, thus extending motor lifespan. Accurate initial temperature monitoring and subsequent temperature prediction can prevent overheating in a timely manner, avoiding potential damage and ensuring the safe operation of the motor. Simultaneously, this precise temperature monitoring and prediction reduces failures and downtime caused by overheating, effectively lowering maintenance and repair costs and improving motor efficiency and economic benefits.

[0087] Optionally, the preset protection threshold includes a first threshold and a second threshold, and the step of performing temperature protection control on the motor based on the comparison result includes: When the current predicted temperature is greater than or equal to the first threshold and less than the second threshold, the speed of the motor is reduced. When the current predicted temperature is greater than or equal to the second threshold, the motor is controlled to stop running, and the motor restart function is locked.

[0088] Specifically, this process describes a motor temperature protection control strategy that uses two different temperature threshold levels to implement different protection measures.

[0089] Two protection thresholds are preset: a first threshold (T1) and a second threshold (T2), where T2 > T1. These two thresholds are set according to the motor's design parameters and safe operation requirements to distinguish between different levels of temperature warnings and emergency situations.

[0090] When the current predicted temperature reaches or exceeds the first threshold T1 but is below the second threshold T2, a measure will be taken to reduce the motor speed. This speed reduction can reduce the motor load and heat generation, thereby preventing the temperature from rising further and providing the motor with an opportunity to cool down.

[0091] When the current predicted temperature reaches or exceeds the second threshold T2, more stringent measures will be taken, namely, immediately stopping the motor and locking the motor restart function. This measure can prevent the motor from continuing to operate at extreme temperatures, thereby avoiding potential damage or malfunction.

[0092] The locked motor restart function means that the motor will not restart automatically without manual intervention. This requires operators to inspect and perform necessary maintenance after the motor stops running to ensure that it restarts within a safe temperature range.

[0093] By setting two different temperature threshold levels, graded protection for motor temperature is achieved. This strategy protects the motor to varying degrees, preventing overheating damage. Timely measures, such as reducing speed or stopping operation, reduce the risk of motor operation at high temperatures, helping to extend motor lifespan. The lock-restart function ensures the motor will not automatically restart until the temperature drops to a safe level, enhancing system safety. Furthermore, this protection strategy reduces unexpected downtime and maintenance needs due to overheating, improving maintenance efficiency and reducing costs. Automated temperature monitoring and protection control simplify operating procedures, reduce reliance on manual monitoring, and make motor operation simpler and more reliable.

[0094] like Figure 3 As shown in the figure, an embodiment of the present invention provides a sensorless motor stator temperature protection device, which is applied to a motor control system. The sensorless motor stator temperature protection device includes: The data acquisition unit is used to acquire the current voltage, current current and current speed of the motor when the motor in the motor control system is running, and to determine the corresponding temperature rise coefficient and thermal equilibrium temperature based on the current voltage, current current and current speed. The processing unit is configured to obtain the current estimated temperature based on the current voltage, the current current, and the current rotational speed; determine the current predicted temperature based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient; compare the current predicted temperature with a preset protection threshold, and perform temperature protection control on the motor based on the comparison result.

[0095] This invention provides a sensorless motor stator temperature protection device, comprising a memory and a processor; the memory is used to store a computer program; the processor is used to implement the sensorless motor stator temperature protection method as described above when the computer program is executed.

[0096] This invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the sensorless motor stator temperature protection method described above.

[0097] The present invention describes a sensorless motor stator temperature protection device that can serve as a server or client of the present invention, and is an example of a hardware device that can be applied to various aspects of the present invention. The sensorless motor stator temperature protection device is intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The sensorless motor stator temperature protection device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0098] The sensorless motor stator temperature protection device includes a computing unit that can perform various appropriate actions and processes based on a computer program stored in read-only memory (ROM) or a computer program loaded from a storage unit into random access memory (RAM). The RAM can also store various programs and data required for device operation. The computing unit, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0099] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs. Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units can be implemented in hardware or as software functional units.

[0100] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A sensorless motor stator temperature protection method, characterized in that, The sensorless motor stator temperature protection method, applied to motor control systems, includes: When the motor in the motor control system is running, the current voltage, current current and current speed of the motor are acquired, and the corresponding temperature rise coefficient and thermal equilibrium temperature are determined based on the current voltage, current current and current speed. The current estimated temperature is obtained based on the current voltage, the current current, and the current rotation speed; The current predicted temperature is determined based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient. The current predicted temperature is compared with a preset protection threshold, and the motor is subjected to temperature protection control based on the comparison result.

2. The sensorless motor stator temperature protection method according to claim 1, characterized in that, The step of obtaining the current estimated temperature based on the current voltage, the current current, and the current rotation speed includes: Obtain the previously estimated temperature; The current estimated temperature is obtained based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed.

3. The sensorless motor stator temperature protection method according to claim 2, characterized in that, The step of obtaining the current estimated temperature based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed includes: The current estimated temperature is obtained using Equation 1, based on the previous estimated temperature, the current voltage, the current current, and the current rotational speed. Wherein, Equation 1 is: ； in, For the current estimated temperature, The current voltage, For the current, Due to environmental temperature differences, For motor operating efficiency, The current rotational speed, For heat capacity data, This relates the motor's heat dissipation capacity to the current rotational speed. The previous estimated temperature.

4. The sensorless motor stator temperature protection method according to claim 1, characterized in that, The step of determining the current predicted temperature based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient includes: The difference data is determined based on the current estimated temperature and the thermal equilibrium temperature; The current predicted temperature is obtained based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient.

5. The sensorless motor stator temperature protection method according to claim 4, characterized in that, The step of obtaining the current predicted temperature based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient includes: The current predicted temperature is obtained using Equation 2, based on the difference data, the previous estimated temperature, and the corresponding temperature rise coefficient. Wherein, the second formula is: ； Where T is the current predicted temperature. The previous estimated temperature, For adjustment coefficients, The temperature rise coefficient is... The difference data is referred to here.

6. The sensorless motor stator temperature protection method according to claim 2, characterized in that, The process of obtaining the initial stator resistance temperature includes: When the motor is in the startup phase, the current and voltage information of the motor are acquired; Based on a preset stator identification method, the initial stator resistance temperature is determined according to the current information and the voltage information.

7. The sensorless motor stator temperature protection method according to claim 1, characterized in that, The preset protection threshold includes a first threshold and a second threshold, and the step of performing temperature protection control on the motor based on the comparison result includes: When the current predicted temperature is greater than or equal to the first threshold and less than the second threshold, the speed of the motor is reduced. When the current predicted temperature is greater than or equal to the second threshold, the motor is controlled to stop running, and the motor restart function is locked.

8. A sensorless motor stator temperature protection device, characterized in that, The sensorless motor stator temperature protection device, applied to motor control systems, includes: The data acquisition unit is used to acquire the current voltage, current current and current speed of the motor when the motor in the motor control system is running, and to determine the corresponding temperature rise coefficient and thermal equilibrium temperature based on the current voltage, current current and current speed. The processing unit is configured to obtain the current estimated temperature based on the current voltage, the current current, and the current rotational speed; determine the current predicted temperature based on the current estimated temperature, the thermal equilibrium temperature, the previous estimated temperature, and the corresponding temperature rise coefficient; compare the current predicted temperature with a preset protection threshold, and perform temperature protection control on the motor based on the comparison result.

9. A sensorless motor stator temperature protection device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the sensorless motor stator temperature protection method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the sensorless motor stator temperature protection method as described in any one of claims 1 to 7.

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