Motor rotor temperature determination method, control equipment and computer readable storage medium
By constructing a rotor thermal network model and energy conservation relationship, and using motor operating parameters to calculate rotor temperature in real time, the problems of rotor temperature measurement accuracy and cost are solved, and stable and accurate rotor temperature determination is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG GEELY HLDG GRP CO LTD
- Filing Date
- 2026-01-12
- Publication Date
- 2026-05-01
AI Technical Summary
Existing technologies for measuring motor rotor temperature have poor accuracy, high cost, and insufficient real-time performance, making it impossible to accurately determine rotor temperature under conditions requiring continuous operation, such as vehicle driving.
By constructing a rotor thermal network model, and utilizing readily available real-time motor operating parameters (speed, bus current) and temperature parameters (stator temperature, coolant temperature), combined with the energy conservation relationship, the rotor loss power and key heat exchange power are calculated in real time, enabling real-time, closed-loop estimation of rotor temperature.
Without the need for expensive temperature sensors and interrupting motor operation, it can continuously measure rotor temperature under all operating conditions, providing stable and accurate results, and achieving low-cost rotor temperature determination.
Smart Images
Figure CN121966410A_ABST
Abstract
Description
Methods for determining motor rotor temperature, control equipment, and computer-readable storage media Technical Field
[0001] This application relates to the field of motor control technology, and in particular to a method for determining motor rotor temperature, a control device, and a computer-readable storage medium. Background Technology
[0002] With the rapid development of new energy vehicles, industrial automation, aerospace and other fields, permanent magnet synchronous motors have become the mainstream choice for drive systems due to their advantages such as high power density, high efficiency and high response speed.
[0003] The rotor temperature of an electric motor has a decisive impact on its safety and lifespan. Currently, rotor temperature is typically determined by directly measuring it with relevant measuring equipment, calculating it using empirical formulas, or using the back electromotive force (EMF) method. However, directly measuring rotor temperature is inaccurate, costly, and complex; the empirical formula method cannot assign an initial rotor temperature value upon the next power-on, resulting in poor accuracy; and the back EMF method requires unloading the motor current, leading to poor real-time performance and making it unsuitable for continuous operation conditions such as vehicle driving. Summary of the Invention
[0004] The main objective of this application is to provide a method, control device, and computer-readable storage medium for determining the rotor temperature of an electric motor, aiming to achieve accurate determination of the rotor temperature of an electric motor in real time, simply and at low cost.
[0005] This application provides a method for determining the rotor temperature of an electric motor. The method includes: acquiring the initial rotor temperature and the historical rotor temperature of the target motor at the previous moment; determining the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor; inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor of the target motor at the current moment; and, based on the energy conservation relationship on the rotor and using the initial rotor temperature as a reference, processing the first thermal power, the second thermal power, and the rotor loss power to obtain the rotor temperature of the target motor at the current moment.
[0006] In one embodiment, the step of processing the first thermal power, the second thermal power, and the rotor loss power based on the initial rotor temperature, according to the energy conservation relationship on the rotor, to obtain the rotor temperature of the target motor at the current moment includes: performing time integration on the sum of the first thermal power, the second thermal power, and the rotor loss power to obtain accumulated heat; calculating the ratio between the accumulated heat and the rotor heat capacity to obtain the rotor temperature rise value; and calculating the sum between the rotor temperature rise value and the initial rotor temperature to obtain the rotor temperature of the target motor at the current moment.
[0007] In one embodiment, the step of obtaining the initial rotor temperature of the target motor includes: obtaining the current shutdown duration of the target motor; if the shutdown duration is greater than a preset duration threshold, using the current stator temperature of the target motor as the initial rotor temperature; if the shutdown duration is less than or equal to the preset duration threshold, obtaining the current air gap temperature of the target motor and the shutdown rotor temperature of the target motor at the moment before the last shutdown, and determining the initial rotor temperature of the target motor based on the air gap temperature and the shutdown rotor temperature.
[0008] In one embodiment, the step of obtaining the air gap temperature of the target motor at the current moment includes: calculating a first temperature difference between the stator temperature and the coolant temperature of the target motor at the current moment; and using the sum of the product of the first temperature difference and a preset weighting coefficient and the coolant temperature as the air gap temperature.
[0009] In one embodiment, the step of determining the initial rotor temperature of the target motor based on the air gap temperature and the stopped rotor temperature includes: calculating a second temperature difference between the air gap temperature and the stopped rotor temperature; and using the sum of the air gap temperature and the second temperature difference as the initial rotor temperature of the target motor.
[0010] In one embodiment, the step of determining the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor includes: obtaining the rotor loss power corresponding to the current operating speed and bus current based on a preset mapping relationship between the operating speed, bus current and rotor loss power, and using it as the rotor loss power of the target motor at the current moment.
[0011] In one embodiment, before the step of inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor of the target motor at the current moment, the method further includes: obtaining the operating parameters and actual rotor temperature of the target motor under various preset operating conditions; determining the rotor heat capacity, the first thermal resistivity between the stator and the rotor, and the second thermal resistivity between the coolant and the rotor of the target motor through simulation fitting based on the operating parameters and actual rotor temperature of the target motor under various preset operating conditions; and constructing the rotor thermal network model based on the rotor heat capacity, the first thermal resistivity, and the second thermal resistivity.
[0012] In one embodiment, the step of inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor of the target motor at the current moment includes: after inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into the pre-constructed rotor thermal network model, the rotor thermal network model determines the differences between the stator temperature and the coolant temperature and the historical rotor temperature, respectively, to obtain a third temperature difference and a fourth temperature difference; the first thermal power is calculated based on the first thermal resistivity and the third temperature difference, and the second thermal power is calculated based on the second thermal resistivity and the fourth temperature difference.
[0013] In addition, to achieve the above objectives, this application also provides a control device, the control device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the motor rotor temperature determination method as described above.
[0014] In addition, to achieve the above objectives, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the motor rotor temperature determination method as described above.
[0015] In addition, to achieve the above objectives, this application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the motor rotor temperature determination method as described above.
[0016] This application provides a method for determining the rotor temperature of an electric motor, comprising: acquiring the initial rotor temperature and the historical rotor temperature of the target motor at the previous moment; determining the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor; inputting the current stator temperature, coolant temperature and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor at the current moment; and, based on the energy conservation relationship on the rotor and taking the initial rotor temperature as a reference, processing the first thermal power, the second thermal power and the rotor loss power to obtain the rotor temperature of the target motor at the current moment.
[0017] Therefore, the technical solution provided in this application, based on a pre-constructed rotor thermal network model, utilizes readily available real-time motor operating parameters (speed, bus current) and temperature parameters (stator temperature, coolant temperature) to achieve online calculation of rotor loss power and key heat exchange power. Subsequently, based on the energy conservation relationship on the rotor, and using the initial temperature as an iterative benchmark, all the aforementioned thermal parameters are comprehensively processed to complete the real-time, closed-loop estimation of the rotor temperature. Thus, the technical solution provided in this application eliminates the need for expensive and unreliable temperature sensors and other measuring equipment, and also eliminates the need to interrupt normal motor operation when measuring rotor temperature; it can continuously measure rotor temperature under all operating conditions. Furthermore, since the technical solution provided in this application is based on a deterministic physical model (i.e., the rotor thermal network model) and the principle of energy conservation to determine the rotor temperature, its estimation results are stable and accurate.
[0018] In summary, the technical solution provided in this application can accurately determine the rotor temperature of a motor in real time, easily, and at low cost. Attached Figure Description
[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.
[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 is a flowchart illustrating the method for determining motor rotor temperature according to the first embodiment of this application; Figure 2 is a schematic diagram illustrating the rotor thermal network model according to the first embodiment of this application; Figure 3 is a flowchart illustrating the method for determining motor rotor temperature according to the second embodiment of this application; Figure 4 is a schematic diagram illustrating the structure of the hardware operating environment involved in the embodiments of this application.
[0022] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0023] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.
[0024] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.
[0025] With the rapid development of new energy vehicles, industrial automation, aerospace and other fields, permanent magnet synchronous motors have become the mainstream choice for drive systems due to their advantages such as high power density, high efficiency and high response speed.
[0026] The rotor temperature of an electric motor has a decisive impact on its safety and lifespan. Currently, rotor temperature is typically determined by directly measuring it with relevant measuring equipment, calculating it using empirical formulas, or using the back electromotive force (EMF) method. However, directly measuring rotor temperature is inaccurate, costly, and complex; the empirical formula method cannot assign an initial rotor temperature value upon the next power-on, resulting in poor accuracy; and the back EMF method requires unloading the motor current, leading to poor real-time performance and making it unsuitable for continuous operation conditions such as vehicle driving.
[0027] Based on this, this application provides a method for determining the rotor temperature of a motor, comprising: acquiring the initial rotor temperature of the target motor and the historical rotor temperature at the previous moment; determining the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor; inputting the current stator temperature, coolant temperature and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor at the current moment; and, based on the energy conservation relationship on the rotor, processing the first thermal power, the second thermal power and the rotor loss power with the initial rotor temperature as a reference to obtain the rotor temperature of the target motor at the current moment.
[0028] Therefore, the technical solution provided in this application, based on a pre-constructed rotor thermal network model, utilizes readily available real-time motor operating parameters (speed, bus current) and temperature parameters (stator temperature, coolant temperature) to achieve online calculation of rotor loss power and key heat exchange power. Subsequently, based on the energy conservation relationship on the rotor, and using the initial temperature as an iterative benchmark, all the aforementioned thermal parameters are comprehensively processed to complete the real-time, closed-loop estimation of the rotor temperature. Thus, the technical solution provided in this application eliminates the need for expensive and unreliable temperature sensors and other measuring equipment, and also eliminates the need to interrupt normal motor operation when measuring rotor temperature; it can continuously measure rotor temperature under all operating conditions. Furthermore, since the technical solution provided in this application is based on a deterministic physical model (i.e., the rotor thermal network model) and the principle of energy conservation to determine the rotor temperature, its estimation results are stable and accurate.
[0029] In summary, the technical solution provided in this application can accurately determine the rotor temperature of a motor in real time, easily, and at low cost.
[0030] The subject of the method for determining the rotor temperature of the motor in this application can be a control device with data processing, network communication and program operation functions, or a control system or control circuit that can realize the above functions. This embodiment does not specifically limit it.
[0031] The following description uses a control device as the execution subject to illustrate the various embodiments.
[0032] This application proposes a method for determining the rotor temperature of a motor according to a first embodiment. Referring to Figure 1, the method may include steps S10 to S40: Step S10: Obtain the initial rotor temperature and the historical rotor temperature of the target motor at the previous moment. It should be noted that the target motor is the motor whose rotor temperature needs to be measured. The number of target motors can be one or more, and this embodiment does not specifically limit this. The initial rotor temperature refers to the initial value assigned to the rotor temperature estimation when the target motor starts up or when the target motor enters the rotor temperature estimation process. The rotor temperature of the target motor at the previous moment is referred to as the historical rotor temperature.
[0033] In one feasible implementation, the step of obtaining the initial rotor temperature of the target motor may include steps S11 to S13: Step S11, obtaining the current downtime of the target motor; it should be noted that the downtime refers to the time interval between the last power-off (i.e., stopping work) and the current power-on of the target motor.
[0034] When obtaining the current downtime of the target motor, in one feasible implementation, if the motor controller or vehicle controller has a non-volatile memory area and a real-time clock, the power-off timestamp can be recorded when the target motor is powered off; after power-on, the current timestamp is read, and the time difference between the current timestamp and the power-off timestamp is determined to obtain the current downtime of the target motor. In another feasible implementation, the downtime can also be determined by associating the status of the vehicle or other systems. Specifically, the sleep / wake-up records of the vehicle network can be read, or the resting time of the low-voltage battery can be detected to determine the current downtime of the target motor. This embodiment does not specifically limit the implementation of step S11.
[0035] Step S12: If the shutdown duration exceeds the preset duration threshold, the stator temperature of the target motor at the current moment is used as the initial rotor temperature. It should be noted that the preset duration threshold is used as the basis for determining whether the motor has been sufficiently cooled to a basic balance with the environment and stator temperature. It can be a default value or can be flexibly set by the user according to the actual situation. This embodiment does not make specific limitations on this.
[0036] Understandably, if the shutdown time exceeds the preset time threshold, the target motor has been completely cooled down, and the rotor temperature, stator temperature, and ambient temperature tend to be consistent. Therefore, the current stator temperature of the target motor can be directly used as the initial rotor temperature.
[0037] Step S13: If the shutdown duration is less than or equal to a preset duration threshold, obtain the air gap temperature of the target motor at the current moment and the shutdown rotor temperature of the target motor at the moment before the last shutdown, and determine the initial rotor temperature of the target motor based on the air gap temperature and the shutdown rotor temperature.
[0038] It should be noted that air gap temperature refers to the temperature of the air gap region between the stator and rotor of the motor. The rotor temperature of the target motor at the moment before the last shutdown is called the shutdown rotor temperature.
[0039] Understandably, when the shutdown duration is less than or equal to the preset duration threshold, the target motor is not fully cooled. In this case, by introducing the air gap temperature, which better characterizes the local environment of the rotor, and based on the thermal state of the previous shutdown, the cooling process of the target motor during the shutdown can be simulated. This allows for the estimation of an initial value that is closer to the actual residual temperature of the rotor than the stator temperature, thus improving the accuracy of the subsequently determined motor rotor temperature.
[0040] When obtaining the air gap temperature of the target motor at the current moment, the first temperature difference between the stator temperature and the coolant temperature of the target motor at the current moment can be calculated; the sum of the product of the first temperature difference and the preset weighting coefficient and the coolant temperature is taken as the air gap temperature.
[0041] The temperature difference between the stator temperature and the coolant temperature of the target motor at the current moment is referred to as the first temperature difference. The preset weighting coefficient is the weighting coefficient between the winding temperature and the coolant temperature of the target motor. It can be a default value or can be flexibly set by the user according to the actual situation. This embodiment does not impose specific limitations on it. The process of obtaining the air gap temperature of the target motor at the current moment can be expressed as the following formula 1.
[0042] T air =T cool +r*(T str -T cool Formula 1; where T air T is the air gap temperature. cool T represents the coolant temperature. str is the stator temperature, and r is a preset weighting coefficient.
[0043] When determining the initial rotor temperature of a target motor based on the air gap temperature and the stopped rotor temperature, in one feasible implementation, a second temperature difference between the air gap temperature and the stopped rotor temperature can be calculated; the sum of the air gap temperature and the second temperature difference is taken as the initial rotor temperature of the target motor.
[0044] The temperature difference between the air gap temperature and the stopped rotor temperature is referred to as the second temperature difference. The process of determining the initial rotor temperature of the target motor based on the air gap temperature and the stopped rotor temperature can be expressed as the following formula 2.
[0045] T rtrini =T air +T diff Formula 2; where T rtrini T is the initial rotor temperature. air T is the air gap temperature. diff This is the temperature difference between the air gap temperature and the stopped rotor temperature.
[0046] In another feasible implementation, a two-dimensional cooling curve table indexed by the initial temperature difference (i.e., the temperature difference between the air gap temperature and the stopped rotor temperature) and the shutdown duration can be established in advance. Then, by looking up the table using the second temperature difference and the shutdown duration as indexes, the attenuated temperature difference can be determined. Adding it to the air gap temperature, the initial rotor temperature can be obtained.
[0047] Step S20: Determine the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor. It should be noted that rotor loss power refers to the power of energy loss (such as eddy current loss, hysteresis loss, etc.) generated on the rotor side (mainly permanent magnets) during motor operation, which is converted into heat energy. It is the main internal heat source causing rotor temperature rise.
[0048] In one feasible implementation, step S20 may include: obtaining the rotor loss power corresponding to the current operating speed and bus current based on a preset mapping relationship between operating speed, bus current and rotor loss power, and using it as the rotor loss power of the target motor at the current moment.
[0049] The mapping relationship between operating speed, bus current and rotor loss power can be recorded using a relationship table, relationship curve or other means. This embodiment does not impose any specific limitations on this.
[0050] In another feasible implementation, a rotor loss model including components such as eddy current loss and hysteresis loss can be established in advance based on the electromagnetic theory of motors. Therefore, step S20 can include: inputting the current operating speed and bus current of the target motor into the pre-built rotor loss model to obtain the rotor loss power of the target motor at the current moment.
[0051] The above are only two feasible implementation methods of step S20 provided in this embodiment. This embodiment does not specifically limit the implementation method of step S20.
[0052] Step S30: Input the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into the pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor at the current moment. It should be noted that the rotor thermal network model is a physical model that equates the heat conduction and convection processes of the motor to a circuit network composed of elements such as thermal resistance and thermal capacitance. For details, please refer to Figure 2, where t... RTM For rotor temperature, C Rtr For rotor heat capacity, P loss For rotor loss power, t str t is the stator temperature. cool For coolant temperature, g s (n) is the first thermal resistivity between the stator and rotor, g c (n) represents the second thermal resistivity between the coolant and the rotor. The first thermal power refers to the heat exchange power generated due to the temperature difference along the path from the coolant to the rotor; the second thermal power refers to the heat exchange power generated due to the temperature difference along the path from the rotor to the rotor.
[0053] After inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into the pre-built rotor thermal network model, the rotor thermal network model will first determine the differences between the stator temperature and coolant temperature and the historical rotor temperature, respectively, to obtain the third temperature difference and the fourth temperature difference; then, based on the first thermal resistivity and the third temperature difference, the first thermal power is calculated (see Formula 3 below for details), and based on the second thermal resistivity and the fourth temperature difference, the second thermal power is calculated (see Formula 4 below for details).
[0054] P str =g s (t str -t htr Formula 3; where P str The first thermal power from the coolant to the rotor, g s (n) is the first thermal resistivity between the stator and rotor, t str t is the stator temperature. htr This represents the historical rotor temperature.
[0055] P cool =g c (t cool -t htr Formula 4; where P cool For the second thermal power from stator to rotor, g c (n) is the second thermal resistivity between the coolant and the rotor, t cool This refers to the coolant temperature.
[0056] Step S40: Based on the energy conservation relationship on the rotor, and taking the initial rotor temperature as a reference, process the first thermal power, the second thermal power, and the rotor loss power to obtain the rotor temperature of the target motor at the current moment.
[0057] It should be noted that the energy conservation relationship on the rotor means that the change in the internal energy of the rotor thermodynamic system is equal to the integral of the net heat inflow. Specifically, it can be expressed as: Rotor temperature rise = (Cumulative effect of (self-generated heat + externally transferred heat - heat transferred outward) / Rotor heat capacity.
[0058] In one feasible implementation, step S40 may include steps S41 to S43: Step S41, integrating the sum of the first thermal power, the second thermal power and the rotor loss power over time to obtain the accumulated heat; Step S42, calculating the ratio between the accumulated heat and the rotor heat capacity to obtain the rotor temperature rise value; Step S43, calculating the sum between the rotor temperature rise value and the initial rotor temperature to obtain the rotor temperature of the target motor at the current moment.
[0059] The implementation process of the above steps S41~S43 can be expressed as the following formula 5.
[0060] Formula 5; where T is the rotor temperature of the target motor at the current moment, C is the rotor heat capacity, t0 is the previous moment, t1 is the current moment, and P... loss P represents the rotor loss power. str P is the first thermal power from the coolant to the rotor. cool T is the second thermal power from the stator to the rotor. rtrini This is the initial rotor temperature.
[0061] As described above, the technical solution provided in this embodiment achieves online calculation of rotor power loss and key heat exchange power by utilizing readily available real-time motor operating parameters (speed, bus current) and temperature parameters (stator temperature, coolant temperature) based on a pre-constructed rotor thermal network model. Subsequently, according to the energy conservation principle on the rotor, using the initial temperature as an iterative benchmark, all the aforementioned thermal parameters are comprehensively processed to complete the real-time, closed-loop estimation of the rotor temperature. Therefore, the technical solution provided in this embodiment does not require expensive and unreliable temperature sensors or other measuring equipment, nor does it require interrupting the normal operation of the motor; it can continuously measure the rotor temperature under all operating conditions. Furthermore, since the technical solution provided in this embodiment is based on a deterministic physical model (i.e., the rotor thermal network model) and the principle of energy conservation to determine the rotor temperature, its estimation results are stable and accurate.
[0062] Therefore, the technical solution provided in this embodiment can accurately determine the rotor temperature of the motor in real time, easily and at low cost.
[0063] Based on the first embodiment described above, a second embodiment of the method for determining motor rotor temperature of this application is proposed. In the second embodiment, referring to Figure 3, before step S30, the method for determining motor rotor temperature may further include steps S01 to S03: Step S01, obtaining the operating parameters and actual rotor temperature of the target motor under various preset operating conditions; it should be noted that each preset operating condition refers to a series of test condition combinations pre-set to fully cover the actual operating state of the motor, which may typically include different ambient temperatures, motor speeds, output torque / load, coolant flow rates, and other boundary conditions. Operating parameters may include, but are not limited to, operating speed, bus current, stator temperature, coolant temperature, etc., and this embodiment does not specifically limit these parameters. The actual rotor temperature refers to the true value of the rotor temperature obtained directly through experimental means, which can be used as the target value or label for model fitting.
[0064] Step S02: Based on the operating parameters of the target motor under various preset operating conditions and the actual rotor temperature, the rotor heat capacity, the first thermal resistivity between the stator and rotor, and the second thermal resistivity between the coolant and rotor of the target motor are determined through simulation fitting. It should be noted that the rotor heat capacity is a lumped parameter used to characterize the rotor's own heat storage capacity. The first thermal resistivity is a lumped parameter used to characterize the ease of heat transfer between the stator and rotor; it is usually identified as a fixed value or a function related to variables such as rotational speed. The second thermal resistivity is a lumped parameter used to characterize the ease of heat transfer between the coolant and rotor; it is also usually identified as a fixed value or a function related to variables such as rotational speed.
[0065] By combining the rotor thermal network model shown in Figure 2 with the thermal resistance and thermal capacity parameters, the physical characteristics of the rotor thermal network model can be analyzed in depth, and analytical relationships for determining the key parameters of the model (i.e., rotor thermal capacity, first thermal resistivity, and second thermal resistivity) can be obtained. Specifically: when the motor runs under a certain constant operating condition for a sufficiently long time, the entire thermal system reaches thermal equilibrium, and the rotor temperature will tend to a stable value. At this time, the net heat power flowing into the rotor is zero. Based on the thermal equilibrium condition of the rotor thermal network model shown in Figure 2, the calculation expression for the rotor steady-state temperature can be derived as follows: Formula 6; where, This is the rotor steady-state temperature.
[0066] The dynamic response speed of the rotor thermal network model is characterized by the thermal time constant τ, which determines how quickly the rotor temperature changes from its initial value to its steady-state value. This time constant τ can be determined by the rotor heat capacity and total thermal conductivity (the reciprocal of thermal resistance), as shown in Equation 7 below.
[0067] Formula 7; where, at time t=τ, the change in rotor temperature will reach approximately 63.2% of its total change (from initial state to steady state). Therefore, during parameter identification, by analyzing the rotor's heating or cooling curves under known operating conditions and measuring the time required for the temperature change to reach 63.2%, the time constant τ can be determined. After determining the time constant τ, the rotor's heat capacity, first thermal resistivity, and second thermal resistivity can be jointly solved using Formula 6.
[0068] Therefore, step S02 can be based on the above technical principles to perform simulation fitting in order to determine the rotor heat capacity, the first thermal resistance between the stator and the rotor, and the second thermal resistance between the coolant and the rotor of the target motor.
[0069] In one feasible implementation, step S02 may include: establishing a parameterized simulation program for the rotor thermal network model in an environment such as MATLAB, and then importing the working parameters as inputs and the actual rotor temperature corresponding to the working parameters as the target value (or label) into the parameterized simulation program; then using built-in optimization algorithms (such as least squares method, genetic algorithm, particle swarm optimization algorithm) with the goal of minimizing the root mean square error between the model predicted temperature and the measured temperature, automatically iteratively searching for a set of optimal model parameters (i.e., rotor heat capacity, first thermal resistivity and second thermal resistivity).
[0070] Step S03: Construct a rotor thermal network model based on rotor heat capacity, first thermal resistivity, and second thermal resistivity.
[0071] As described above, this embodiment first collects the motor's operating parameters and actual rotor temperature under various preset operating conditions to form a complete experimental dataset. Then, based on this dataset, the rotor heat capacity, the first thermal resistivity between the stator and rotor, and the second thermal resistivity between the coolant and rotor are determined through simulation fitting. Subsequently, a rotor thermal network model can be constructed using the rotor heat capacity, the first thermal resistivity, and the second thermal resistivity. Thus, this embodiment extracts and solidifies the complex and difficult-to-model transient heat conduction and convection processes inside the motor into a lumped parameter model characterized by a few parameters with clear physical meaning. This eliminates the need for complex and unstable real-time parameter identification during online estimation or reliance on empirical formulas with limited accuracy. By simply calling this pre-constructed physical model with determined parameters, the system can quickly deduce the key heat exchange power in real-time calculations. This fundamentally avoids the cumulative estimation errors caused by online drift or mismatch of model parameters, significantly improving the long-term stability and adaptability of rotor temperature tracking, laying the foundation for a high-precision, low-cost rotor temperature determination process.
[0072] This application embodiment also provides a control device, which may include: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the motor rotor temperature determination method in the above embodiment.
[0073] Referring now to Figure 4, a schematic diagram of a control device suitable for implementing embodiments of this application is shown. The control device shown in Figure 4 is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.
[0074] As shown in Figure 4, the control device may include a processing unit 101 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in read-only memory 102 or a program loaded from storage device 103 into random access memory 104. Random access memory 104 also stores various programs and data required for the operation of the control device. The processing unit 101, read-only memory 102, and random access memory 104 are interconnected via bus 105. Input / output interface 106 is also connected to bus 105. Typically, the following systems can be connected to input / output interface 106: input devices 107 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 108 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 103 including, for example, magnetic tape, hard disks, etc.; and communication devices 109. Communication device 109 allows the control device to communicate wirelessly or wiredly with other devices to exchange data. Although the diagram shows control equipment with various systems, it should be understood that it is not required to implement or have all of the systems shown. More or fewer systems may be implemented alternatively.
[0075] In particular, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 103, or installed from read-only memory 102. When the computer program is executed by processing device 101, it performs the functions defined in the methods of the embodiments of this application.
[0076] The control device provided in this application, employing the motor rotor temperature determination method described in the above embodiments, can accurately determine the motor rotor temperature in real time, simply, and at low cost. Compared with the prior art, the beneficial effects of the control device provided in this application are the same as those of the motor rotor temperature determination method provided in the above embodiments, and other technical features of the control device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.
[0077] It should be understood that various parts of the embodiments of this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.
[0078] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the above claims.
[0079] This application also provides a computer-readable storage medium storing a computer program that can run on a processor. The computer program is used to execute the motor rotor temperature determination method in the above embodiments.
[0080] The computer-readable storage medium provided in this application embodiment may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.
[0081] The aforementioned computer-readable storage medium may be included in the control device; or it may exist independently and not assembled into the control device.
[0082] The aforementioned computer-readable storage medium carries one or more programs. When the aforementioned one or more programs are executed by the control device, the control device causes the control device to: acquire the initial rotor temperature of the target motor and the historical rotor temperature at the previous moment; determine the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor; input the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor at the current moment; and, based on the energy conservation relationship on the rotor and using the initial rotor temperature as a reference, process the first thermal power, the second thermal power, and the rotor loss power to obtain the current rotor temperature of the target motor.
[0083] Computer program code for performing the operations of this disclosure can be written in one or more programming languages or a combination thereof, including object-oriented programming languages such as Java, Smalltalk, and C++, and conventional procedural programming languages such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).
[0084] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.
[0085] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.
[0086] The computer-readable storage medium provided in this application embodiment stores computer-readable program instructions for executing the above-described motor rotor temperature determination method, enabling accurate determination of the motor rotor temperature in real time, conveniently, and at low cost. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application embodiment are the same as the beneficial effects of the motor rotor temperature determination method provided in the above embodiments, and will not be repeated here.
[0087] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the motor rotor temperature determination method described above.
[0088] The computer program product provided in this application embodiment can accurately determine the rotor temperature of a motor in real time, easily, and at low cost. Compared with the prior art, the beneficial effects of the computer program product provided in this application embodiment are the same as those of the motor rotor temperature determination method provided in the above embodiments, and will not be repeated here.
[0089] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.
Claims
1. A method for determining the rotor temperature of an electric motor, characterized in that, The method includes: acquiring the initial rotor temperature of the target motor and the historical rotor temperature at the previous moment; determining the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor; inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor at the current moment; and, based on the energy conservation relationship on the rotor and using the initial rotor temperature as a reference, processing the first thermal power, the second thermal power, and the rotor loss power to obtain the current rotor temperature of the target motor.
2. The method as described in claim 1, characterized in that, The step of obtaining the rotor temperature of the target motor at the current moment by processing the first thermal power, the second thermal power, and the rotor loss power based on the energy conservation relationship on the rotor and the initial rotor temperature as a reference includes: performing time integration on the sum of the first thermal power, the second thermal power, and the rotor loss power to obtain the accumulated heat; calculating the ratio between the accumulated heat and the rotor heat capacity to obtain the rotor temperature rise value; and calculating the sum between the rotor temperature rise value and the initial rotor temperature to obtain the rotor temperature of the target motor at the current moment.
3. The method as described in claim 1, characterized in that, The step of obtaining the initial rotor temperature of the target motor includes: obtaining the current shutdown duration of the target motor; if the shutdown duration is greater than a preset duration threshold, using the current stator temperature of the target motor as the initial rotor temperature; if the shutdown duration is less than or equal to the preset duration threshold, obtaining the current air gap temperature of the target motor and the shutdown rotor temperature of the target motor at the moment before the last shutdown, and determining the initial rotor temperature of the target motor based on the air gap temperature and the shutdown rotor temperature.
4. The method as described in claim 3, characterized in that, The step of obtaining the air gap temperature of the target motor at the current moment includes: calculating a first temperature difference between the stator temperature and the coolant temperature of the target motor at the current moment; and taking the sum of the product of the first temperature difference and a preset weighting coefficient and the coolant temperature as the air gap temperature.
5. The method as described in claim 3, characterized in that, The step of determining the initial rotor temperature of the target motor based on the air gap temperature and the stopped rotor temperature includes: calculating a second temperature difference between the air gap temperature and the stopped rotor temperature; and taking the sum of the air gap temperature and the second temperature difference as the initial rotor temperature of the target motor.
6. The method as described in claim 1, characterized in that, The step of determining the rotor loss power of the target motor at the current moment based on the current operating speed and bus current of the target motor includes: obtaining the rotor loss power corresponding to the current operating speed and bus current based on a preset mapping relationship between the operating speed, bus current and rotor loss power, and using it as the rotor loss power of the target motor at the current moment.
7. The method as described in claim 1, characterized in that, Before the step of inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor of the target motor at the current moment, the method further includes: obtaining the operating parameters and actual rotor temperature of the target motor under various preset operating conditions; determining the rotor heat capacity, the first thermal resistivity between the stator and the rotor, and the second thermal resistivity between the coolant and the rotor of the target motor through simulation fitting based on the operating parameters and actual rotor temperature of the target motor under various preset operating conditions; and constructing the rotor thermal network model based on the rotor heat capacity, the first thermal resistivity, and the second thermal resistivity.
8. The method as described in claim 7, characterized in that, The step of inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into a pre-constructed rotor thermal network model to obtain the first thermal power from the coolant to the rotor and the second thermal power from the stator to the rotor of the target motor at the current moment includes: after inputting the current stator temperature, coolant temperature, and historical rotor temperature of the target motor into the pre-constructed rotor thermal network model, the rotor thermal network model determines the differences between the stator temperature and the coolant temperature and the historical rotor temperature, respectively, to obtain a third temperature difference and a fourth temperature difference; the first thermal power is calculated based on the first thermal resistivity and the third temperature difference, and the second thermal power is calculated based on the second thermal resistivity and the fourth temperature difference.
9. A control device, characterized in that, The control device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the motor rotor temperature determination method as described in any one of claims 1 to 8.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the motor rotor temperature determination method as described in any one of claims 1 to 8.