Motor temperature estimation method, apparatus and electronic device

Abstract

The application provides a motor temperature estimation method and device and electronic equipment, and relates to the technical field of motors.The method comprises the following steps: determining the operation condition of a motor; when the operation condition is a medium-high speed operation condition, determining the motor winding temperature based on an average thermal model; when the operation condition is a locked-rotor operation condition, determining the motor winding temperature based on a locked-rotor thermal model; and when the operation condition is a low-speed operation condition, determining the motor winding temperature based on a dynamic weight smoothing fusion thermal model; wherein the dynamic weight smoothing fusion thermal model is used for weighted fusion of a first winding temperature estimated by the average thermal model under the low-speed operation condition and a second winding temperature estimated by the locked-rotor thermal model under the low-speed operation condition. According to different operation conditions, the application uses a suitable model to estimate the temperature, thereby effectively improving the accuracy and reliability of motor temperature estimation.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically, to a method, apparatus, and electronic device for estimating motor temperature. Background Technology

[0002] Brushless direct current motors (BLDC) are widely used in electric actuators due to their advantages such as low cost, long lifespan, high efficiency, low noise, and precise controllability. These applications include gear selector actuators in automatic transmissions, electric drive disengagement actuators, steer-by-wire systems, brake-by-wire systems, and active suspensions. Since the temperature of the motor windings directly affects the motor's lifespan and operational stability, accurately determining the motor winding temperature is crucial for motor thermal management and system safety.

[0003] In related technologies, the temperature of motor windings is mainly obtained through built-in temperature sensors or temperature estimation models. However, on the one hand, the built-in sensor solution increases the size of the motor and the cost of hardware, and the detection accuracy is easily affected by vibration, resulting in insufficient reliability; on the other hand, existing temperature estimation models are mostly based on simplified first-order or second-order average thermal models. Related technologies use such models to estimate the temperature under all operating conditions, ignoring the differences in heat generation of the motor under different operating conditions, which leads to a large deviation between the temperature estimation results and the actual values, resulting in low accuracy. Summary of the Invention

[0004] The problem addressed by this invention is how to improve the accuracy and reliability of motor winding temperature estimation.

[0005] To address the above problems, the present invention provides a method, apparatus, electronic device, and storage medium for estimating motor temperature.

[0006] In a first aspect, the present invention provides a method for estimating motor temperature, comprising: Determine the operating conditions of the motor; When the operating condition is a medium-to-high speed condition, the motor winding temperature is determined based on the average thermal model. When the operating condition is a stalled rotor condition, the motor winding temperature is determined based on the stalled rotor thermal model; When the operating condition is low speed, the motor winding temperature is determined based on a dynamic weighted smooth fusion thermal model. The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

[0007] Optionally, determining the operating conditions of the motor includes: Get the motor speed; The operating conditions of the motor are determined based on the motor speed.

[0008] Optionally, determining the operating condition of the motor based on the motor speed includes: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor speed is higher than or equal to the first preset threshold and lower than the second preset threshold, the operating condition is determined to be the low-speed condition. When the motor speed is higher than or equal to the second preset threshold, the operating condition is determined to be the medium-high speed condition.

[0009] Optionally, determining the operating condition of the motor based on the motor speed includes: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor is in the stall condition and the motor speed rises to a level not lower than the first preset threshold, it is determined that the motor has entered a low-speed condition. When the motor is in the low-speed condition, and the motor speed rises to a value not lower than the upper limit of the hysteresis interval and continues for a preset duration, it is determined that the motor has entered the medium-high speed condition. When the motor is in the medium-high speed condition, and the motor speed decreases to no higher than the lower limit of the hysteresis interval and no lower than the first preset threshold, it is determined that the motor has entered the low speed condition. Wherein, the upper limit of the hysteresis interval is higher than the lower limit of the hysteresis interval, and the lower limit of the hysteresis interval is higher than the first preset threshold.

[0010] Optionally, determining the motor winding temperature based on the average thermal model includes: Obtain the three-phase current, initial winding temperature, and ambient temperature of the motor; The heating power of the first winding of the motor under the medium-high speed condition is determined based on the three-phase current and the initial temperature of the winding, and the heating power of the iron loss of the motor is determined based on the motor speed. The differential equation of the average thermal model is established based on the heating power of the first winding, the heating power of the iron loss, and the ambient temperature. The differential equation of the average thermal model is discretized and iteratively calculated to obtain the motor winding temperature.

[0011] Optionally, determining the motor winding temperature based on the stalled rotor thermal model includes: Obtain the three-phase current and initial winding temperature of the motor; The heating power of the second winding of the motor under the stall condition is determined based on the three-phase current and the initial temperature of the winding. The differential equation of the stall rotor thermal model is established based on the heating power of the second winding; The differential equation of the stalled rotor thermal model is solved to obtain the motor winding temperature.

[0012] Optionally, determining the motor winding temperature based on the dynamic weighted smooth fusion thermal model includes: Obtain the three-phase current and initial winding temperature of the motor; Based on the three-phase current and the initial temperature of the winding, the temperature of the first winding is determined according to the average thermal model, and the temperature of the second winding is determined according to the stalled rotor thermal model; The motor winding temperature is obtained by weighting and fusing the first winding temperature and the second winding temperature using a weighting factor. The weighting factor is determined based on the motor speed and a second preset threshold.

[0013] Optionally, the motor temperature estimation method further includes: When the operating condition is switched from any one of the stall condition, the low-speed condition, and the medium-high-speed condition to another condition, the motor winding temperature determined in the condition before the switch is used as the initial winding temperature in the condition after the switch.

[0014] In a second aspect, the present invention provides a motor temperature estimation device, comprising: The operating condition determination module is used to determine the operating conditions of the motor. The first estimation module is used to determine the motor winding temperature based on the average thermal model when the operating condition is a medium-high speed condition. The second estimation module is used to determine the motor winding temperature based on the stalled rotor thermal model when the operating condition is a stalled rotor condition. The third estimation module is used to determine the motor winding temperature based on a dynamic weighted smooth fusion thermal model when the operating condition is low speed. The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

[0015] Thirdly, the present invention provides an electronic device, including a memory and a processor; The memory is used to store computer programs; The processor is configured to implement the motor temperature estimation method as described in the first aspect when executing the computer program.

[0016] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the motor temperature estimation method as described in the first aspect.

[0017] The beneficial effects of the motor temperature estimation method, device, electronic device, and storage medium of the present invention are as follows: By identifying the real-time operating conditions of the motor and adaptively matching the winding temperature calculation strategy, the applicability problem of a single model under all operating conditions is solved. Specifically, when the operating condition is medium-to-high speed, an average thermal model that reflects the overall temperature rise trend is used to determine the motor winding temperature, which can accurately characterize the characteristics of the equalization of heat generation and heat dissipation of the motor under medium-to-high speed conditions, thereby effectively improving the accuracy of winding temperature estimation under medium-to-high speed conditions. When the operating condition is stalled, a stalled thermal model that reflects the characteristics of localized concentrated heat generation and static heat dissipation is used to determine the motor winding temperature, which can accurately characterize the uneven heat generation and heat accumulation effect of the motor under stalled conditions, thereby effectively improving the accuracy of winding temperature estimation under stalled conditions. When operating at low speed, a dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under low-speed conditions and the second winding temperature estimated by the stalled thermal model under low-speed conditions. This reflects the characteristics of the motor under low-speed conditions, which combine the concentrated heating characteristics of stalled conditions with the thermal equilibrium characteristics of medium- and high-speed conditions, thus effectively improving the accuracy of temperature estimation under low-speed conditions. In summary, using a suitable model for temperature estimation under different operating conditions effectively solves the problem of the applicability of a single model under different operating conditions, improving the accuracy and continuity of winding temperature estimation under all operating conditions. Furthermore, the temperature estimation results are not affected by external interference such as mechanical vibration, significantly improving the reliability of the temperature estimation results. Attached Figure Description

[0018] Figure 1 A schematic flowchart of a motor temperature estimation method provided in an embodiment of the present invention; Figure 2 A schematic diagram of a second-order average thermal model provided in an embodiment of the present invention; Figure 3 A schematic diagram of the stall rotor thermal model provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a motor temperature estimation device provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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".

[0023] 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.

[0024] With the rapid development of automotive electrification, drive-by-wire, and intelligentization, brushless direct current (BLDC) motors are widely used in electric actuators for automatic transmission gear selection, steering-by-wire, brake-by-wire, and active suspension due to their advantages such as low cost, high efficiency, long lifespan, and precise controllability. The operating temperature of the BLDC motor in the electric actuator directly determines the reliability and service life of the system. If the winding temperature is too high, it will not only cause the enameled wire insulation layer to age, melt, or even short-circuit and burn out, but may also cause irreversible demagnetization of the permanent magnet and accelerate the wear of mechanical parts. Therefore, accurately obtaining the motor winding temperature is the key to achieving precise thermal management.

[0025] Due to the compact internal space of BLDC motors, directly installing temperature sensors is costly and susceptible to vibration interference. Related technologies commonly employ lumped parameter methods based on parameters such as current, speed, and ambient temperature to establish a first- or second-order average thermal model to estimate the motor winding temperature. However, the operating conditions of BLDC motors are complex, specifically: First, electric actuators often face complex operating conditions such as frequent starts and stops, impact loads, intermittent stalling, or large fluctuations in low speed (such as gear tooth collision during shifting). During intermittent stalling or extremely low-speed operation, the motor generates a large amount of heat, which is concentrated in the currently energized winding. Due to the thermal resistance in the heat transfer within the motor, the heat cannot be dissipated in time, which can easily cause the temperature of local hot spots in the winding within the slot to rise sharply at a rate far exceeding the average temperature rise.

[0026] Secondly, BLDC motors typically employ a six-step commutation control with two-phase conduction, resulting in significant condition-dependent heating and cooling characteristics. During medium-to-high-speed operation, the internal airflow turbulence generated by rotor rotation and the alternating energization of each phase winding "averages" heating and cooling in both space and time. However, under heavy load and low-speed operation, this unevenness becomes significantly apparent: on the one hand, the energization time of certain two phase windings is longer, and the time constant for cooling at low speeds is much greater than the time constant for temperature rise; on the other hand, the rotor speed is low at low speeds, significantly reducing convective cooling capacity. Furthermore, the difference in energization time between phase windings during stable low-speed operation and frequent low-speed fluctuations also leads to different heat accumulation characteristics.

[0027] Related technologies use fixed first- or second-order average thermal models to estimate the motor winding temperature under all operating conditions, ignoring the differences in motor winding heating under different operating conditions. This results in a systematic bias in the estimation of the winding temperature in the slot, making it difficult to meet the high reliability thermal protection requirements of modern electric actuators.

[0028] To address the problems existing in the aforementioned related technologies, this embodiment provides a method, apparatus, electronic device, and storage medium for estimating motor temperature.

[0029] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for estimating motor temperature, comprising: S100 determines the operating conditions of the motor.

[0030] Specifically, since the heat generation and heat dissipation of BLDC motors differ at different speeds, operating conditions can be classified based on speed. Operating conditions can include stall conditions, low-speed conditions, and medium-to-high-speed conditions.

[0031] S200, when the operating condition is medium-high speed, the motor winding temperature is determined based on the average thermal model.

[0032] Specifically, under medium and high speed conditions, although the motor control logic is two phases energized and one phase is disconnected, due to the extremely high six-step commutation frequency, the duty cycle of each phase winding tends to be balanced, and the uneven heating phenomenon is effectively "averaged" over a long time scale. Moreover, the forced convection heat dissipation brought about by high-speed rotation is significantly enhanced. Therefore, an average thermal model that is computationally efficient and can reflect the overall temperature rise trend can be adopted.

[0033] S300, when the operating condition is a stalled condition, the motor winding temperature is determined based on the stalled thermal model.

[0034] Specifically, under stall conditions, the motor is in a stationary state with two phase windings continuously energized and the third phase disconnected. This results in concentrated and continuous copper loss heating in the energized two-phase windings, while the de-energized third-phase winding has no heat source, exhibiting spatial heating non-uniformity and heat accumulation effect. If an average thermal model is used at this time, the local hot spot temperature will be underestimated. Therefore, a stall thermal model that can accurately characterize local concentrated heating and static heat dissipation characteristics is adopted.

[0035] S400, when the operating condition is low speed, the motor winding temperature is determined based on the dynamic weighted smooth fusion thermal model; The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

[0036] Specifically, under low-speed conditions, the motor not only has the characteristic of continuous concentrated heat generation during stall, but also has the complete thermal equilibrium state at medium and high speeds. It is also accompanied by nonlinear mismatch of heat generation and heat dissipation time constants and dynamic accumulation of hot spot temperature. Therefore, a dynamic weighted smooth fusion thermal model can be adopted to smoothly fuse the stall model and the average model according to the real-time operating conditions. This fusion mechanism compensates for the applicability boundary defects of the single model under varying operating conditions in a physical sense.

[0037] In this embodiment, by identifying the real-time operating conditions of the motor, an adaptive matching strategy for calculating winding temperature is adopted to solve the problem of the applicability of a single model under all operating conditions. Specifically, when the operating condition is medium-to-high speed, an average thermal model that reflects the overall temperature rise trend is used to determine the motor winding temperature. This accurately characterizes the characteristics of the motor's heat generation and heat dissipation equalization under medium-to-high speed conditions, thereby effectively improving the accuracy of winding temperature estimation under these conditions. When the operating condition is stalled, a stalled thermal model that reflects the characteristics of localized concentrated heat generation and static heat dissipation is used to determine the motor winding temperature. This accurately characterizes the uneven heat generation and heat accumulation effect of the motor under stalled conditions, thereby effectively improving the accuracy of winding temperature estimation under these conditions. When operating at low speed, a dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under low-speed conditions and the second winding temperature estimated by the stalled thermal model under low-speed conditions. This reflects the characteristics of the motor under low-speed conditions, which combine the concentrated heating characteristics of stalled conditions with the thermal equilibrium characteristics of medium- and high-speed conditions, thus effectively improving the accuracy of temperature estimation under low-speed conditions. In summary, using a suitable model for temperature estimation under different operating conditions effectively solves the problem of the applicability of a single model under different operating conditions, improving the accuracy and continuity of winding temperature estimation under all operating conditions. Furthermore, the temperature estimation results are not affected by external interference such as mechanical vibration, significantly improving the reliability of the temperature estimation results.

[0038] Optionally, determining the operating conditions of the motor includes: Get the motor speed; The operating conditions of the motor are determined based on the motor speed.

[0039] In this optional embodiment, the operating conditions are divided according to the difference in heat generation and heat dissipation state represented by the motor speed, which enables each operating condition to be accurately matched with its corresponding thermal characteristics, thereby achieving accurate identification of the current operating state of the motor.

[0040] Optionally, determining the operating condition of the motor based on the motor speed includes: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor speed is higher than or equal to the first preset threshold and lower than the second preset threshold, the operating condition is determined to be the low-speed condition. When the motor speed is higher than or equal to the second preset threshold, the operating condition is determined to be the medium-high speed condition.

[0041] Specifically, considering the theoretical motor speed when the motor is stalled... The threshold is zero, but slight peristalsis may occur during actual operation, so a first preset threshold is set. As a boundary for determining a stalled turn: when When this occurs, the condition is determined to be a stalled operation.

[0042] when hour, The second preset threshold indicates that the motor is rotating but at a low speed, and is therefore classified as a low-speed operating condition.

[0043] when When the motor is in a high speed range, it is determined to be a medium-to-high speed operating condition.

[0044] In this optional embodiment, the operating conditions of the motor can be accurately determined by matching the motor speed with the speed range corresponding to different operating conditions.

[0045] Optionally, determining the operating condition of the motor based on the motor speed includes: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor is in the stall condition and the motor speed rises to a level not lower than the first preset threshold, it is determined that the motor has entered a low-speed condition. When the motor is in the low-speed condition, and the motor speed rises to a value not lower than the upper limit of the hysteresis interval and continues for a preset duration, it is determined that the motor has entered the medium-high speed condition. When the motor is in the medium-high speed condition, and the motor speed decreases to no higher than the lower limit of the hysteresis interval and no lower than the first preset threshold, it is determined that the motor has entered the low speed condition. Wherein, the upper limit of the hysteresis interval is higher than the lower limit of the hysteresis interval, and the lower limit of the hysteresis interval is higher than the first preset threshold.

[0046] Specifically, in addition to directly dividing the operating conditions based on the threshold, a hysteresis interval can also be introduced to divide the operating conditions, so as to avoid frequent switching of operating conditions when the motor speed fluctuates near the threshold.

[0047] The upper limit of the hysteresis interval can be: The lower limit of the hysteresis interval can be: , This is the preset oscillation threshold.

[0048] Under stalled operation, when When the time is reached, it indicates that the motor has started to rotate, confirming that the motor has entered low-speed operation.

[0049] Under low-speed operating conditions, when Furthermore, if the preset duration is maintained, it indicates that the motor is continuously operating at medium to high speed, thus confirming the switch from low-speed to medium-to-high-speed operation. When the motor is operating at medium to high speed, the heat generation and dissipation are balanced, so the urgency of determining the motor winding temperature for motor protection is not high. Introducing a duration confirmation can avoid false triggering caused by speed fluctuations and improve the reliability of operating condition switching.

[0050] Under medium to high speed operating conditions, when This indicates that the motor has switched from medium-high speed operation to low speed operation. When the motor is running at low speed, there is concentrated heat generation, and it is necessary to quickly determine the temperature of the motor windings for motor protection. Therefore, it is not necessary to confirm the temperature over a continuous period of time, in order to improve the response speed.

[0051] Because stalled operation is the most dangerous, in low-speed or medium-to-high-speed operation, as long as a stalled rotor is detected... That is, to determine It immediately switches to stall condition, quickly starts the stall thermal model to estimate the temperature, and then protects the motor.

[0052] In this optional embodiment, a hysteresis interval is introduced at the switching boundary between low-speed and medium-to-high-speed operating conditions, which can effectively suppress frequent model switching caused by small fluctuations in motor speed, thereby improving the accuracy and reliability of operating condition switching.

[0053] Optionally, determining the motor winding temperature based on the average thermal model includes: Obtain the three-phase current, initial winding temperature, and ambient temperature of the motor; The heating power of the first winding of the motor under the medium-high speed condition is determined based on the three-phase current and the initial temperature of the winding, and the heating power of the iron loss of the motor is determined based on the motor speed. The differential equation of the average thermal model is established based on the heating power of the first winding, the heating power of the iron loss, and the ambient temperature. The differential equation of the average thermal model is discretized and iteratively calculated to obtain the motor winding temperature.

[0054] Specifically, based on the lumped parameter method, an average thermal model is established; a simplified second-order average thermal model can be used, such as... Figure 2 As shown. The model defines several key temperature nodes: Winding temperature; Stator temperature; Motor casing temperature; Ambient temperature; These temperature nodes are connected by thermal resistance and thermal capacity, forming a heat flow path from left to right: heat source (winding / stator) → thermal capacity → thermal resistance → casing → thermal resistance → environment.

[0055] Thermal resistance from winding to core; Thermal resistance from the iron core to the BLDC motor housing; : Thermal resistance of the BLDC motor housing to the external environment; : ; Due to the complexity of heat dissipation from a BLDC motor to the environment, this thermal resistance can be equivalently represented as: In the formula and These are empirical fitting coefficients used to linearly approximate nonlinear heat dissipation processes (such as natural convection and radiation).

[0056] For winding heat capacity; For the heat capacity of the iron core; This represents the heating power of the first winding. This refers to the heating power of the iron core, i.e., the heating power caused by iron loss.

[0057] Heat generation power of the first winding (That is, the copper loss heating power of the winding), can be calculated using the following formula:

[0058]

[0059] In the formula: 、 and These are the three-phase currents; The temperature of the corresponding phase winding is The resistance value at that time; The temperature of the corresponding phase winding is The resistance value at that time, Normal temperature is usually 25 degrees Celsius. This is a correction factor; T The initial winding temperature can be the motor winding temperature estimated at the previous moment.

[0060] The iron losses of the stator core include hysteresis loss, eddy current loss, and abnormal losses. From the core loss separation model, it can be seen that the heating power generated by iron losses... It can be calculated using the following formula:

[0061] In the formula: This refers to the motor speed of the BLDC motor; and These are undetermined coefficients, which can be obtained by fitting experimental data.

[0062] Parameters in the second-order average thermal model: 、 、 In and 、 、 These parameters can be determined by fitting experimental data.

[0063] Based on Kirchhoff's laws, establish the differential equation for the second-order thermal model:

[0064] In the formula, This refers to the length of time required to enter medium-to-high speed operating conditions.

[0065] Discretizing the above equations transforms the continuous-time differential equations into discrete-time iterative difference equations. Iterative calculations then allow for the real-time calculation of the motor winding temperature. and stator temperature (i.e., core temperature).

[0066] In this optional embodiment, under medium- and high-speed operating conditions, the average thermal model that can reflect the overall temperature rise trend is used to calculate the motor winding temperature, which can accurately reflect the heating and cooling status of the motor under medium- and high-speed operating conditions, thereby effectively improving the estimation accuracy of the motor winding temperature.

[0067] Optionally, determining the motor winding temperature based on the stalled rotor thermal model includes: Obtain the three-phase current and initial winding temperature of the motor; The heating power of the second winding of the motor under the stall condition is determined based on the three-phase current and the initial temperature of the winding. The differential equation of the stall rotor thermal model is established based on the heating power of the second winding; The differential equation of the stalled rotor thermal model is solved to obtain the motor winding temperature.

[0068] Specifically, although the motor's thermal path still follows the same pattern under stall conditions... Figure 2 The two follow the same pattern, but their heat sources, heat dissipation capabilities, thermal time constants, and final thermal equilibrium temperatures are completely different. The stall condition is an extreme condition in which almost all the heat is concentrated on the small mass of the winding, making it difficult to conduct to the casing for dissipation in a timely manner.

[0069] Under stalled operation, the iron loss heating power of the stator core Approximately zero; poor heat dissipation capacity, high thermal resistance. Approximately equal to infinity; the winding heating increases sharply due to the increase in locked-rotor current, leading to a high rate of temperature change in the winding. The temperature change curve is relatively large, approximating a rapidly rising straight line.

[0070] Simplified thermal model of stall condition, such as Figure 3 As shown in the figure, This refers to the heating power of the second winding when the rotor is stalled, i.e., the heating power caused by copper losses. The heat capacity during stall; This refers to the temperature of the motor windings when the rotor is stalled.

[0071] Heat generation power of the second winding during stall The calculation formula is:

[0072]

[0073]

[0074] In the formula: This is the locked rotor current, which is the three-phase current. 、 and The maximum absolute value. The heat capacity during stall can be determined experimentally. The temperature of the corresponding phase winding is The resistance value at that time; The temperature of the corresponding phase winding is The resistance value at that time, Normal temperature is usually 25 degrees Celsius. This is a correction factor; T The initial winding temperature can be the motor winding temperature estimated at the previous moment.

[0075] The simplified differential equation expression for the stalled rotor thermal model is as follows:

[0076] Motor winding temperature under stall condition The expression can be described as:

[0077] In the formula: The temperature of the winding at the initial moment of entering the stalled rotor condition; To enter the stall t The motor winding temperature at that moment; t The duration of time required to enter stall condition.

[0078] In this optional embodiment, under stall conditions, a stall thermal model that can accurately characterize localized concentrated heat generation and static heat dissipation is adopted, which can accurately reflect the heat generation and heat dissipation status of the motor under stall conditions, thereby effectively improving the estimation accuracy of the motor winding temperature.

[0079] Optionally, determining the motor winding temperature based on the dynamic weighted smooth fusion thermal model includes: Obtain the three-phase current and initial winding temperature of the motor; Based on the three-phase current and the initial temperature of the winding, the temperature of the first winding is determined according to the average thermal model, and the temperature of the second winding is determined according to the stalled rotor thermal model; The motor winding temperature is obtained by weighting and fusing the first winding temperature and the second winding temperature using a weighting factor. The weighting factor is determined based on the motor speed and a second preset threshold.

[0080] Specifically, under low-speed operating conditions, the average thermal model and the stall thermal model are run simultaneously, and the temperature of the first winding is determined based on the average thermal model. The temperature of the second winding was determined based on the locked rotor thermal model. For details, please refer to the process of determining the motor winding temperature under medium- and high-speed operating conditions and stalled operating conditions described above.

[0081] The motor winding temperature under low-speed conditions can be determined using the following formula:

[0082] In the formula, As a weighting factor, The range of values ​​is Weighting factors This is used to characterize the differences in thermal characteristics of BLDC motors under different operating conditions and their impact on the accumulation of hot spot temperature. Specifically, it covers: uneven heat distribution and mismatch between heat generation and heat dissipation time constants under low-speed conditions, as well as the deviation of heat dissipation characteristics between medium- and high-speed conditions and stall conditions relative to low-speed conditions.

[0083] Weighting factors Based on the real-time speed of the BLDC motor A smooth transition between "0" (complete average thermal model) and "1" (complete stall rotor thermal model).

[0084] when (During stalled operation) It is completely equivalent to the stall-to-heat model.

[0085] During medium and high speed operating conditions, It is completely equivalent to the average heat model.

[0086] When operating at low speeds, a weighted smooth fusion of the average thermal model and the stalled rotor thermal model is used.

[0087] The weighted smooth fusion function can be nonlinearly fused, such as an sigmoid function, to better reflect the actual changes in heat dissipation characteristics.

[0088]

[0089] In the formula: For a fitting parameter greater than 1 (e.g.) ). The range of values ​​is This makes the actual rotational speed The threshold value approaching medium to high speed (i.e., the second preset threshold). At that time, it is closer to the average thermal model; at actual rotational speed When the engine speed approaches the stall speed (i.e., the first speed threshold), it is closer to the stall thermal model.

[0090] In this optional embodiment, under low-speed conditions, the motor exhibits both the concentrated heat generation characteristics of stalled operation and the thermal equilibrium characteristics of medium-to-high-speed operation, which a single model cannot adequately address. By weighted fusion of the winding temperature estimates from the stalled thermal model and the average thermal model, the applicability boundary defects of a single model in the transitional conditions between stalled and medium-to-high-speed operation can be effectively compensated, thereby significantly improving the continuity and accuracy of motor winding temperature estimation under transitional conditions.

[0091] Optionally, the motor temperature estimation method further includes: When the operating condition is switched from any one of the stall condition, the low-speed condition, and the medium-high-speed condition to another condition, the motor winding temperature determined in the condition before the switch is used as the initial winding temperature in the condition after the switch.

[0092] For example, when the operating condition switches from a stalled state to a low-speed state, the motor winding temperature determined under the stalled state is used as the initial winding temperature under the low-speed state. When the operating condition switches from a medium-high speed state to a low-speed state, the motor winding temperature determined under the medium-high speed state is used as the initial winding temperature under the low-speed state. That is, the final output value of the operating condition at the time of switching (which may include the estimated motor winding temperature or core temperature) is inherited as the initial winding temperature of the next operating condition.

[0093] In this optional embodiment, the thermal state inheritance mechanism can eliminate the temperature estimate jump caused by model switching, thus ensuring the continuity and stability of the temperature estimate.

[0094] like Figure 4As shown, an embodiment of the present invention provides a motor temperature estimation device 400, comprising: Operating condition determination module 410 is used to determine the operating conditions of the motor; The first estimation module 420 is used to determine the motor winding temperature based on the average thermal model when the operating condition is a medium-high speed operating condition. The second estimation module 430 is used to determine the motor winding temperature based on the stalled rotor thermal model when the operating condition is a stalled rotor condition. The third estimation module 440 is used to determine the motor winding temperature based on a dynamic weighted smooth fusion thermal model when the operating condition is a low-speed condition. The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

[0095] The motor temperature estimation device in this embodiment is used to implement the motor temperature estimation method described above. Its advantages over the prior art are the same as the advantages of the motor temperature estimation method described above over the prior art, and will not be repeated here.

[0096] Optionally, the operating condition determination module 410 includes: The acquisition module is used to acquire the motor speed; The segmentation module is used to determine the operating conditions of the motor based on the motor speed.

[0097] Optionally, the modules are specifically used for: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor speed is higher than or equal to the first preset threshold and lower than the second preset threshold, the operating condition is determined to be the low-speed condition. When the motor speed is higher than or equal to the second preset threshold, the operating condition is determined to be the medium-high speed condition.

[0098] Optionally, the module division is also specifically used for: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor is in the stall condition and the motor speed rises to a level not lower than the first preset threshold, it is determined that the motor has entered a low-speed condition. When the motor is in the low-speed condition, and the motor speed rises to a value not lower than the upper limit of the hysteresis interval and continues for a preset duration, it is determined that the motor has entered the medium-high speed condition. When the motor is in the medium-high speed condition, and the motor speed decreases to no higher than the lower limit of the hysteresis interval and no lower than the first preset threshold, it is determined that the motor has entered the low speed condition. Wherein, the upper limit of the hysteresis interval is higher than the lower limit of the hysteresis interval, and the lower limit of the hysteresis interval is higher than the first preset threshold.

[0099] Optionally, the first estimation module 420 is specifically used for: acquiring the three-phase current, initial winding temperature, and ambient temperature of the motor; determining the first winding heating power of the motor under the medium-to-high speed operating condition based on the three-phase current and the initial winding temperature; determining the iron loss heating power of the motor based on the motor speed; establishing the differential equation of the average thermal model based on the first winding heating power, the iron loss heating power, and the ambient temperature; and discretizing and iteratively calculating the differential equation of the average thermal model to obtain the motor winding temperature.

[0100] Optionally, the second estimation module 430 is specifically used for: obtaining the three-phase current and initial winding temperature of the motor; determining the second winding heating power of the motor under the stall condition based on the three-phase current and the initial winding temperature; establishing the differential equation of the stall thermal model based on the second winding heating power; and solving the differential equation of the stall thermal model to obtain the motor winding temperature.

[0101] Optionally, the third estimation module 440 is specifically used for: acquiring the three-phase current and initial winding temperature of the motor; determining the first winding temperature according to the average thermal model based on the three-phase current and the initial winding temperature, and determining the second winding temperature according to the stalled rotor thermal model; weighting and fusing the first winding temperature and the second winding temperature using a weighting factor to obtain the motor winding temperature; wherein the weighting factor is determined based on the motor speed and a second preset threshold.

[0102] Optionally, the motor temperature estimation device further includes an inheritance module, which is used to: when the operating condition is switched from any one of the stall condition, the low-speed condition, and the medium-high-speed condition to another condition, use the motor winding temperature determined in the condition before the switch as the initial winding temperature in the condition after the switch.

[0103] like Figure 5 As shown, an electronic device 500 provided in this embodiment of the invention includes a memory 510 and a processor 520; the memory 510 is used to store a computer program; the processor 520 is used to implement the motor temperature estimation method as described above when the computer program is executed.

[0104] Alternatively, an electronic device 500 includes a memory 510 and a processor 520 coupled to the memory 510; the memory 510 is configured to store a computer program; and the processor 520 is configured to perform the following operations when the computer program is executed: Determine the operating conditions of the motor; When the operating condition is a medium-to-high speed condition, the motor winding temperature is determined based on the average thermal model. When the operating condition is a stalled rotor condition, the motor winding temperature is determined based on the stalled rotor thermal model; When the operating condition is low speed, the motor winding temperature is determined based on the dynamic weighted smooth fusion thermal model. The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

[0105] This invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the motor temperature estimation method described above.

[0106] Alternatively, a non-volatile computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform the following operations: Determine the operating conditions of the motor; When the operating condition is a medium-to-high speed condition, the motor winding temperature is determined based on the average thermal model. When the operating condition is a stalled rotor condition, the motor winding temperature is determined based on the stalled rotor thermal model; When the operating condition is low speed, the motor winding temperature is determined based on the dynamic weighted smooth fusion thermal model. The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

[0107] Electronic device 500, which can serve as a server or client of the present invention, is described below as an example of a hardware device applicable to various aspects of the present invention. Electronic device 500 is intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic device 500 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.

[0108] Electronic device 500 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 may 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.

[0109] 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.

[0110] 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 method for estimating motor temperature, characterized in that, include: Determine the operating conditions of the motor; When the operating condition is a medium-to-high speed condition, the motor winding temperature is determined based on the average thermal model. When the operating condition is a stalled rotor condition, the motor winding temperature is determined based on the stalled rotor thermal model; When the operating condition is low speed, the motor winding temperature is determined based on the dynamic weighted smooth fusion thermal model. The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

2. The motor temperature estimation method according to claim 1, characterized in that, The determination of the motor's operating conditions includes: Get the motor speed; The operating conditions of the motor are determined based on the motor speed.

3. The motor temperature estimation method according to claim 2, characterized in that, The step of determining the operating conditions of the motor based on the motor speed includes: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor speed is higher than or equal to the first preset threshold and lower than the second preset threshold, the operating condition is determined to be the low-speed condition. When the motor speed is higher than or equal to the second preset threshold, the operating condition is determined to be the medium-high speed condition.

4. The motor temperature estimation method according to claim 2, characterized in that, The step of determining the operating conditions of the motor based on the motor speed includes: When the motor speed is lower than the first preset threshold, the operating condition is determined to be the stall condition; When the motor is in the stall condition and the motor speed rises to a level not lower than the first preset threshold, it is determined that the motor has entered a low-speed condition. When the motor is in the low-speed condition, and the motor speed rises to a value not lower than the upper limit of the hysteresis interval and continues for a preset duration, it is determined that the motor has entered the medium-high speed condition. When the motor is in the medium-high speed condition, and the motor speed decreases to no higher than the lower limit of the hysteresis interval and no lower than the first preset threshold, it is determined that the motor has entered the low speed condition. Wherein, the upper limit of the hysteresis interval is higher than the lower limit of the hysteresis interval, and the lower limit of the hysteresis interval is higher than the first preset threshold.

5. The motor temperature estimation method according to claim 1, characterized in that, The determination of motor winding temperature based on the average thermal model includes: Obtain the three-phase current, initial winding temperature, and ambient temperature of the motor; The heating power of the first winding of the motor under the medium-high speed condition is determined based on the three-phase current and the initial temperature of the winding, and the heating power of the iron loss of the motor is determined based on the motor speed. The differential equation of the average thermal model is established based on the heating power of the first winding, the heating power of the iron loss, and the ambient temperature. The differential equation of the average thermal model is discretized and iteratively calculated to obtain the motor winding temperature.

6. The motor temperature estimation method according to claim 1, characterized in that, The determination of the motor winding temperature based on the stalled rotor thermal model includes: Obtain the three-phase current and initial winding temperature of the motor; The heating power of the second winding of the motor under the stall condition is determined based on the three-phase current and the initial temperature of the winding. The differential equation of the stall rotor thermal model is established based on the heating power of the second winding; The differential equation of the stalled rotor thermal model is solved to obtain the motor winding temperature.

7. The motor temperature estimation method according to claim 1, characterized in that, The determination of the motor winding temperature based on the dynamic weighted smooth fusion thermal model includes: Obtain the three-phase current and initial winding temperature of the motor; Based on the three-phase current and the initial temperature of the winding, the temperature of the first winding is determined according to the average thermal model, and the temperature of the second winding is determined according to the stalled rotor thermal model; The motor winding temperature is obtained by weighting and fusing the first winding temperature and the second winding temperature using a weighting factor. The weighting factor is determined based on the motor speed and a second preset threshold.

8. The motor temperature estimation method according to any one of claims 5 to 7, characterized in that, Also includes: When the operating condition is switched from any one of the stall condition, the low-speed condition, and the medium-high-speed condition to another condition, the motor winding temperature determined in the condition before the switch is used as the initial winding temperature in the condition after the switch.

9. A motor temperature estimation device, characterized in that, include: The operating condition determination module is used to determine the operating conditions of the motor. The first estimation module is used to determine the motor winding temperature based on the average thermal model when the operating condition is a medium-high speed condition. The second estimation module is used to determine the motor winding temperature based on the stalled rotor thermal model when the operating condition is a stalled rotor condition. The third estimation module is used to determine the motor winding temperature based on a dynamic weighted smooth fusion thermal model when the operating condition is low speed. The dynamic weighted smoothing fusion thermal model is used to weight and fuse the first winding temperature estimated by the average thermal model under the low-speed condition and the second winding temperature estimated by the stall thermal model under the low-speed condition.

10. An electronic device, characterized in that, Including memory and processor; The memory is used to store computer programs; The processor is configured to implement the motor temperature estimation method as described in any one of claims 1 to 8 when executing the computer program.

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