Method, system, and vehicle configured for determining stator resistance of electric motor

Abstract

Methods, systems, and vehicles are provided for determining a stator resistance value of an electric motor. The system may include: an electric motor including a stator and a rotor; a sensor system including sensor data configured to generate sensor data indicative of sensed operating conditions of the electric motor, including current magnitude, current angle, motor speed, stator temperature, and rotor temperature; and a controller operably coupled with the sensor system and the electric motor. The controller is configured to: determine an initial stator resistance value based on a stator reference temperature and estimated data sensor data received from the sensor system; determining a stator temperature coefficient based on the sensor data and the stator non-linear resistance ratio curve; and determining a stator resistance value based on the initial stator resistance value and the stator temperature coefficient.

Description

Technical Field

[0001] The technical field relates generally to electric motor operation and, more particularly, to systems and methods for determining stator resistance of a three-phase alternating current (AC) motor, such as in a vehicle propulsion system. Background Art

[0002] Electric vehicles use control systems to manage performance, efficiency, and the overall driving experience. The control system uses a combination of sensor inputs, algorithms, and mathematical models to provide multiple parameters about the vehicle's operation. One such parameter is stator resistance. The stator is the stationary component of the electric motor, and its resistance is the stator's resistance to the flow of electric current. The control system can use the stator resistance to regulate the current flowing through the motor windings. By regulating the current, the control system can control the torque output and acceleration characteristics of the motor. Accurate knowledge of the stator resistance allows the control system to achieve consistent performance under different operating conditions.

[0003] Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. Summary of the invention

[0004] A method for use with an electric motor is provided. In one example, the method includes utilizing one or more processors: determining, by the one or more processors, an initial stator resistance value based on a stator reference temperature and estimated data or sensor data indicating a sensed condition of the electric motor, the sensed condition including current magnitude, current angle, motor speed, stator temperature of the electric motor, and rotor temperature of the electric motor; determining a stator temperature coefficient based on the sensor data and a stator nonlinear resistance ratio curve; and determining a stator resistance value based on the initial stator resistance value and the stator temperature coefficient.

[0005] In various examples, utilizing one or more processors, a stator reference temperature of the method is determined by: receiving a design resistance value of a stator of an electric motor; determining at least two resistance values ​​of the stator for at least two different reference temperatures of the stator; determining a temperature coefficient value of the stator for each of the at least two different reference temperatures; determining a calculated resistance value of the stator for each of the at least two different reference temperatures based on the at least two resistance values ​​and the temperature coefficient value; determining an error value between the design resistance value and the calculated resistance value at each of the at least two different reference temperatures; determining which of the at least two different reference temperatures has a lowest error value; and setting the one of the at least two different reference temperatures having the lowest error value as the stator reference temperature.

[0006] In various examples, the temperature coefficient value of the method is defined by a non-linear resistance ratio curve.

[0007] In various examples, an initial stator resistance value is determined based on sensor data and a stator reference temperature.

[0008] In various examples, the stator nonlinear resistance ratio curve of the method is based on a stator reference temperature.

[0009] In various examples, the electric motor of the method is a component of a vehicle propulsion system, wherein the stator resistance value is determined during operation of the propulsion system.

[0010] In various examples, the electric motor of the method is a three-phase AC motor.

[0011] In various examples, the method includes adjusting an operating parameter of the electric motor based on the stator resistance value.

[0012] A system for use with an electric motor is provided. In one example, the system includes an electric motor including a stator and a rotor; a sensor system including one or more sensors configured to generate sensor data indicating sensed operating conditions of the electric motor, including current magnitude, current angle, motor speed, stator temperature, and rotor temperature; and a controller operably coupled to the sensor system and the electric motor. The controller is configured to: determine an initial stator resistance value based on a stator reference temperature and estimated data or sensor data received from the sensor system, determine a stator temperature coefficient based on the sensor data and a stator nonlinear resistance ratio curve, and determine a stator resistance value based on the initial stator resistance value and the stator temperature coefficient, through one or more processors.

[0013] In various examples, the stator reference temperature used by the controller of the system is a first reference temperature of a plurality of reference temperatures, wherein each of the plurality of reference temperatures is used to determine a corresponding calculated resistance value of the stator, wherein an error value between the calculated resistance value of the stator and a corresponding designed resistance value is determined at the plurality of reference temperatures, wherein the first reference temperature of the plurality of reference temperatures has a lowest error value. In various examples, the calculated resistance value is based on a plurality of resistance values ​​at each of the plurality of reference temperatures and a temperature coefficient value at each of the plurality of reference temperatures, and the temperature coefficient value is defined by a nonlinear resistance ratio curve.

[0014] In various examples, an initial stator resistance value is determined by a controller of the system based on sensor data and a stator reference temperature.

[0015] In various examples, the stator nonlinear resistance ratio curve used by the system controller is based on a stator reference temperature.

[0016] In various examples, an electric motor of the system is a component of a vehicle propulsion system, wherein the stator resistance value is determined during operation of the propulsion system.

[0017] In various examples, the electric motor of the system is a three-phase AC motor.

[0018] In various examples, a controller of the system is configured to adjust, by one or more processors, an operating parameter of the electric motor based on the stator resistance value.

[0019] In one example, a vehicle is provided, the vehicle comprising: an electric motor including a stator and a rotor; a sensor system including one or more sensors configured to generate sensor data indicating sensed operating conditions of the electric motor, including current magnitude, current angle, motor speed, stator temperature, and rotor temperature; and a controller operably coupled to the sensor system and the electric motor. The controller is configured to: determine an initial stator resistance value based on a stator reference temperature and estimated data or sensor data received from the sensor system through one or more processors; determine a stator temperature coefficient based on the sensor data and a stator nonlinear resistance ratio curve; determine a stator resistance value based on the initial stator resistance value and the stator temperature coefficient; and adjust operating parameters of the electric motor based on the stator resistance value.

[0020] In various examples, a stator reference temperature used by a controller of a vehicle is a first reference temperature of a plurality of reference temperatures, wherein each of the plurality of reference temperatures is used to determine a corresponding calculated resistance value of the stator, wherein error values ​​between the calculated resistance value of the stator and a corresponding design resistance value are determined at the plurality of reference temperatures, wherein a first reference temperature of the plurality of reference temperatures has a lowest error value, wherein an initial stator resistance value is determined based on sensor data and the stator reference temperature.

[0021] In various examples, a stator nonlinear resistance ratio curve used by a vehicle controller is based on a stator reference temperature.

[0022] In various examples, an electric motor of a vehicle is a component of a propulsion system of the vehicle, wherein a stator resistance value is determined during operation of the propulsion system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Exemplary embodiments will be described below with reference to the following drawings, wherein like reference numerals represent like elements, and wherein:

[0024] Figure 1 is a functional block diagram of a vehicle having a motor control system configured to operate in conjunction with an electric motor of the vehicle according to an embodiment;

[0025] Figure 2 According to the embodiment Figure 1 A system and data flow diagram of an electric motor control system and an electric motor of a vehicle;

[0026] Figure 3 is a flow chart of a method for determining a stator resistance of an electric motor according to an embodiment;

[0027] Figure 4 is a graph showing resistance values ​​of an exemplary electric motor at various reference temperatures versus motor speed according to an embodiment; and

[0028] Figure 5 is a graph showing resistance ratio versus motor speed of an exemplary electric motor at a reference temperature according to an embodiment. DETAILED DESCRIPTION

[0029] The following detailed description is merely exemplary in nature and is not intended to limit application and use. In addition, there is no intention to be bound by any express or implied theory presented in the previous technical field, background technology, invention content or the following detailed description. As used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic and / or processor device, individually or in any combination, including but not limited to: application-specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated or grouped) and memories that execute one or more software or firmware programs, combinational logic circuits and / or other suitable components that provide the functions.

[0030] Embodiments of the present disclosure may be described herein in terms of functional and / or logical block components and various processing steps. It should be understood that such block components may be implemented by any number of hardware, software, and / or firmware components configured to perform a specified function. For example, embodiments of the present disclosure may employ various integrated circuit components, such as memory elements, digital signal processing elements, logic elements, lookup tables, etc., which may perform various functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any number of systems, and the systems described herein are merely exemplary embodiments of the present disclosure.

[0031] For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control and other functional aspects of the system (as well as the various operating components of the system) may not be described in detail herein. In addition, the connecting lines shown in the various figures included herein are intended to represent example functional relationships and / or physical connections between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the embodiments of the present disclosure.

[0032] The systems and methods described herein facilitate efficient operation of an electric motor, such as a three-phase alternating current (AC) motor. Specifically, the systems and methods provide for accurate determination of stator resistance during operation of the electric motor. In some embodiments, the systems and methods address the nonlinear relationship of stator resistance at various operating speeds of the electric motor by determining a reference temperature with low error relative to other possible reference temperatures. The systems and methods can facilitate efficient determination of stator resistance with relatively little processing power.

[0033] Figure 1 A vehicle 10 is shown according to an exemplary embodiment. In certain embodiments, the vehicle 10 comprises an automobile. The vehicle 10 comprises a motor control system 100 having a database having one or more reference temperatures accessible to the motor control system 100 for calculating or referencing a stator resistance of an electric motor 21 of the vehicle 10. The reference temperature is determined using the method disclosed herein.

[0034] In various embodiments, vehicle 10 can be any of a number of different types of automobiles, such as a sedan, van, truck, or sport utility vehicle (SUV), and in certain embodiments can be two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD), and / or various other types of vehicles or mobile platforms.

[0035] like Figure 1 As shown, the exemplary vehicle 10 generally includes a chassis 12, a body 14, front wheels 16, and rear wheels 18. The body 14 is disposed on the chassis 12 and substantially surrounds the components of the vehicle 10. The body 14 and the chassis 12 may together form a frame. The wheels 16-18 are each rotatably coupled to the chassis 12 near a corresponding corner of the body 14.

[0036] The vehicle 10 also includes a propulsion system 20, a transmission system 22, a steering system 24, a sensor system 28, an actuator system 30, at least one data storage device 32, at least one controller 34, and a connection to a remote system 36 (e.g., via a wireless communication system). The propulsion system 20 includes an electric motor 21, such as a three-phase AC motor. The transmission system 22 is configured to transfer power from the propulsion system 20 to the wheels 16-18 according to a selectable speed ratio. According to various embodiments, the transmission system 22 may include a stepped automatic transmission, a continuously variable transmission, or other suitable transmission. The steering system 24 affects the position of the wheels 16-18. Although depicted as including a steering wheel for illustrative purposes, in some embodiments contemplated within the scope of the present invention, the steering system 24 may not include a steering wheel.

[0037] The sensor system 28 includes one or more sensing devices 40a-40n that sense the external environment, observable conditions of the internal environment, and / or the state or condition of corresponding components of the vehicle 10, and provide such conditions and / or status to other systems of the vehicle 10, such as the controller 34. It should be understood that the vehicle 10 may include any number of sensing devices 40a-40n. The sensing devices 40a-40n may include, but are not limited to, current sensors, voltage sensors, temperature sensors, motor speed sensors, position sensors, etc.

[0038] The actuator system 30 includes one or more actuator devices 42 a - 42 n that control one or more vehicle features, such as, but not limited to, the propulsion system 20 , the drivetrain 22 , and / or the steering system 24 .

[0039] The data storage device 32 stores data used to control the vehicle 10 and / or its systems and components. It will be appreciated that the data storage device 32 may be part of the controller 34, separate from the controller 34, or part of the controller 34 and part of a separate system. The data storage device 32 may be any suitable type of storage device, including various different types of direct access memory and / or other storage devices. In an exemplary embodiment, the data storage device 32 includes a program product from which a computer readable storage device may receive a program to perform one or more embodiments of one or more processes of the present disclosure, such as the following in conjunction with Figure 3 The steps of the process are further discussed. In another exemplary embodiment, the program product may be stored directly in and / or accessed by the memory device and / or one or more other disks and / or other memory devices.

[0040] The controller 34 includes at least one processor 44, a communication bus 45, and a computer readable storage device or medium 46. The processor 44 performs the computational and control functions of the controller 34. The processor 44 can be any custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor in multiple processors associated with the controller 34, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, any combination thereof, or generally any device for executing instructions. The computer readable storage device or medium 46 can include volatile and non-volatile storage in, for example, read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is a permanent or non-volatile memory that can be used to store various operating variables when the processor 44 is powered off. The computer readable storage device or medium 46 may be implemented using any of a variety of known storage devices, such as a PROM (Programmable Read Only Memory), an EPROM (Electrical PROM), an EEPROM (Electrically Erasable PROM), flash memory, or any other electrical, magnetic, optical, or combination storage device capable of storing data, some of which represent executable instructions used by the controller 34 in controlling the vehicle 10. The bus 45 is used to transfer programs, data, status, and other information or signals between the various components of the vehicle 10. The bus 45 may be any suitable physical or logical means of connecting computer systems and components. This includes, but is not limited to, direct hardwired connections, fiber optics, infrared, and wireless bus technologies.

[0041] The instructions may include one or more separate programs, each of which includes an ordered list of executable instructions for implementing logical functions. When executed by the processor 44, the instructions receive and process signals from the sensor system 28, perform logic, calculations, methods and / or algorithms, and generate data based on the logic, calculations, methods and / or algorithms. Figure 1 Only one controller 34 is shown, but embodiments of the vehicle 10 may include any number of controllers 34 that communicate via any suitable communication medium or combination of communication mediums and collaborate to process sensor signals, execute logic, calculations, methods and / or algorithms, and generate data.

[0042] It will be appreciated that the controller 34 may be different from Figure 1embodiment shown. For example, the controller 34 may be coupled to or may utilize one or more remote computer systems and / or other control systems, such as as part of one or more of the vehicle devices and systems described above. It should be understood that although the exemplary embodiment is described in the context of a fully functional computer system, those skilled in the art will recognize that the mechanisms of the present disclosure are capable of being distributed as a program product in which one or more types of non-transitory computer-readable signal-bearing media are used to store the program and its instructions and perform its distribution, such as a non-transitory computer-readable medium that carries the program and contains computer instructions stored therein for causing a computer processor (e.g., processor 44) to execute the program. Such a program product may take a variety of forms, and the present disclosure is equally applicable regardless of the specific type of computer-readable signal-bearing medium used to perform the distribution. Examples of signal-bearing media include recordable media, such as floppy disks, hard disks, memory cards, and optical disks, as well as transmission media, such as digital and analog communication links. It should be understood that cloud-based storage and / or other technologies may also be utilized in certain embodiments. It will be similarly appreciated that the computer system of the controller 34 may also differ in other respects. Figure 1 In the embodiments depicted in FIG. 1 , a computer system such as controller 34 may be coupled to or may otherwise utilize one or more remote computer systems and / or other control systems.

[0043] Remote system 36 may be any suitable computing system or electronic device configured to determine a reference temperature and temperature coefficient of a stator of electric motor 21 of vehicle 10 , generate data including the reference temperature and temperature coefficient, and transmit the relevant data to data storage device 32 and / or controller 34 .

[0044] refer to Figure 2 And continue to refer to Figure 1 , system and data flow diagrams illustrate elements of the motor control system 100 according to various embodiments. It will be appreciated that various embodiments of the motor control system 100 according to the present disclosure may include any number of modules embedded within the controller 34, which may be combined and / or further divided to similarly implement the systems and methods described herein. In addition, inputs to the motor control system 100 may be received from other control modules (not shown) associated with the vehicle 10, and / or determined / modeled by other sub-modules (not shown) within the controller 34. In addition, the inputs may also be subjected to pre-processing, such as sub-sampling, noise reduction, normalization, feature extraction, missing data reduction, etc. In various embodiments, the motor control system 100 includes a motor control module 210, an initial stator resistance module 212, a temperature coefficient module 214, and a stator resistance module 216.

[0045] In various embodiments, the initial stator resistance module 212 receives as input various sensor data generated by the sensor system 28 indicating current magnitude 220, current angle 222, and motor speed 224. The initial stator resistance module 212 determines an initial stator resistance value of the stator at a preprogrammed reference temperature. In some embodiments, the initial stator resistance module 212 determines an initial stator resistance value of the stator using the sensor data. In some embodiments, the initial stator resistance module 212 determines an initial stator resistance value of the stator using calculated and / or estimated values ​​of, for example, current magnitude, current angle, and / or motor speed. The initial stator resistance module 212 generates initial stator resistance data 225 indicating the determined initial stator resistance value.

[0046] In various embodiments, the temperature coefficient module 214 receives as input sensor data generated by the sensor system 28 indicating the stator temperature 226, the rotor temperature 228, and the motor speed 224. The temperature coefficient module 214 determines a temperature coefficient value based on the sensor data and a preprogrammed nonlinear resistance ratio curve. The temperature coefficient module 214 generates temperature coefficient data 230 indicating the determined temperature coefficient value.

[0047] In various embodiments, the stator resistance module 216 receives as input the initial stator resistance data 225 generated by the initial stator resistance module 212 and the temperature coefficient data 230 generated by the temperature coefficient module 214. The stator resistance module 216 determines the stator resistance value based on the initial stator resistance data 225 and the temperature coefficient data 230. In some embodiments, the stator resistance module 216 determines the stator resistance value by multiplying the initial stator resistance value by the temperature coefficient value. The stator resistance module 216 generates stator resistance data 232 indicating the determined stator resistance.

[0048] In various embodiments, the motor control module 210 receives as input the stator resistance data 232 generated by the stator resistance module 216. The motor control module 210 can adjust one or more operating parameters of the electric motor 21 based on the stator resistance value of the stator resistance data 232. In various embodiments, the motor control module 210 can use one or more of the stator resistance value, the motor position 240, the current 238, the direct current (DC) voltage 236, and the torque command 234 to adjust one or more parameters, such as, but not limited to, current control, current reference generation, modulation index calculation, observers, state filters, and online calculations related to motor states at a given speed.

[0049] Reference now Figure 3 , and continue to refer to Figure 1-2According to an exemplary embodiment, a flowchart provides a method 300 for determining a reference temperature and nonlinear resistance ratio curve, which can be uploaded and stored by the motor control system 100 for reference (e.g., by the initial stator resistance module 212 and the temperature coefficient module 214, respectively). It will be understood from the present disclosure that the order of operations within the method 300 is not limited to the following. Figure 3 The method 300 is not performed in the order shown, but may be performed in one or more different orders as applicable and in accordance with the present disclosure. In various embodiments, certain steps of the method 300 may be performed by one or more processors not associated with the vehicle (e.g., of the remote system 36), and certain steps of the method 300 may be performed by one or more processors associated with the vehicle 10 (e.g., the processor 44).

[0050] In one example, method 300 may begin at 310. As will be apparent from the following description, one or more steps of method 300 may be performed one or more times during method 300. Thus, various steps may be described as being performed in one or more iterations. At 312, method 300 may include receiving a design resistance value (R) of a stator of electric motor 21. D In some embodiments, the design resistance value (R D ) can be provided by the manufacturer of the electric motor 21.

[0051] At 314, method 300 may include determining and storing a reference temperature (T x During the first iteration of step 314, the reference temperature (T x ) may be a first reference temperature (eg, 20° C.). During such a first iteration, at 316, the first reference temperature may be set to a first value (eg, T x＝＝1 In subsequent iterations of steps 314 and 316, the reference temperature (T x ) may be a subsequent reference temperature (e.g., 50°C, 90°C, 150°C, etc.) and may be set to a subsequent value (e.g., T x＝2,3,4,…n ).

[0052] At 318, method 300 may include determining, using one or more processors, that the stator is at a reference temperature (T x ) under the resistance value (R s ), which is the reference temperature (T x ) under the current magnitude (I SS ), current angle (I beta ) and motor speed (S M ). For example, Figure 4Indicates the relative speed of the motor (M) at reference temperatures of 20°C (reference 430), 50°C (reference 432), 90°C (reference 434) and 150°C (reference 436). s ; x-axis 410) of the stator resistance value (R s ; y-axis 420). As shown in the figure, the resistance value (R s )With the motor speed (M s ) increases in a nonlinear manner and at the reference temperature (T x ) varies between. s ) is expressed in units (PU), which may involve various units, such as ohms.

[0053] At 320, method 300 may include determining, using one or more processors, a reference temperature (T x )The temperature coefficient of the stator (T coeff ), that is, the nonlinear resistance ratio curve. For example, Figure 5 The reference temperature (T) of 50°C is presented. x ) versus electric motor speed (M s ; x-axis 510). The data corresponds to 20°C / 50°C (reference 530), 90°C / 50°C (reference 532), and 150°C / 50°C (reference 534).

[0054] At 322, method 300 may include utilizing one or more processors to generate a signal based on a resistance value (R s ) and temperature coefficient value (T coeff ) for reference temperature (T x ) Determine the stator reconstruction or calculate the resistance value (R S_calc ).

[0055] At 324, method 300 may include determining, with one or more processors, a design resistance value (R D ) and calculate the resistance value (R S_calc ) between them.

[0056] At 326, method 300 may include updating the reference temperature to a subsequent reference temperature and setting the reference value to the subsequent value at 328. Method 300 may then include repeating steps 318 to 324 for the subsequent reference temperature. x+1 ,T x+2 ,…T x+n ) Repeat the process.

[0057] Once steps 318 to 328 are completed for all reference temperatures, method 300 continues at 330 by storing the reference temperature (Tx The one with the lowest error value among the above is referred to as the final reference temperature (T final ).

[0058] In various embodiments, the final reference temperature (T final ) may be stored in a data storage device 32 on a vehicle (e.g., vehicle 10) for use in determining stator resistance during operation of the electric vehicle. In various embodiments, method 300 may include determining a final reference temperature (T final ) under the resistance value (R s ), and determining a final reference temperature (T final ) under the temperature coefficient (T coeff ). Steps 332 and 334 may be performed during operation of the electric vehicle. In various embodiments, steps 332 and 334 may be performed by one or more processors of the vehicle (eg, processor 44).

[0059] The systems and methods disclosed herein provide various benefits over certain existing systems and methods. For example, various existing systems and methods may be less accurate in determining the stator resistance during operation of an electric motor relative to the systems and methods herein. In some embodiments, by determining a reference temperature with a low error relative to other possible reference temperatures, the systems and methods improve the accuracy of the determination by taking into account the nonlinear relationship of the stator resistance at various operating speeds of the electric motor. In contrast, certain existing systems rely on linear algorithms to calculate and / or estimate the resistance with temperature compensation, such as Equation 1 below.

[0060] R s (T) = R s (25℃)×R s (AC)×(1+α×(T-25℃)), equation (1)

[0061] Among them, R s (T) is the stator DC resistance at T, R s (25°C) is the stator resistance at 25°C, AC is the alternating current (AC) coefficient, α is the material-dependent temperature coefficient, and T is the temperature. Linear methods such as these can result in significant errors (eg, greater than 10%), especially as motor speed increases.

[0062] Although at least one exemplary embodiment has been introduced in the foregoing detailed description, it should be understood that there are a large number of variations. It should also be understood that one or more exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. On the contrary, the foregoing detailed description will provide a convenient roadmap for those skilled in the art to implement one or more exemplary embodiments. It should be understood that various changes may be made to the functions and arrangements of the elements without departing from the scope of the present disclosure as set forth in the attached claims and their legal equivalents.

Claims

1. A method comprising: determining, by one or more processors, an initial stator resistance value of the electric motor based on a stator reference temperature and estimated data or sensor data indicative of sensed conditions of the electric motor, the sensed conditions including current magnitude, current angle, motor speed, stator temperature of the electric motor, and rotor temperature of the electric motor; determining, by one or more processors, a stator temperature coefficient based on the sensor data and a stator nonlinear resistance ratio curve; as well as A stator resistance value is determined by one or more processors based on an initial stator resistance value and a stator temperature coefficient.

2. The method according to claim 1, wherein: The stator reference temperature is determined by: receiving, with the one or more processors, a design resistance value for a stator of the electric motor; determining, using one or more processors, at least two resistance values ​​of the stator for at least two different reference temperatures of the stator; determining, with one or more processors, a temperature coefficient value of the stator for each of at least two different reference temperatures; determining, with one or more processors, a calculated resistance value of the stator for each of at least two different reference temperatures based on the at least two resistance values ​​and the temperature coefficient value; determining, using one or more processors, an error value between a designed resistance value and a calculated resistance value at each of at least two different reference temperatures; determining, using one or more processors, which of at least two different reference temperatures has a lowest error value; as well as The one of at least two different reference temperatures having the lowest error value is set as the stator reference temperature, Wherein, the temperature coefficient value is defined by the nonlinear resistance ratio curve.

3. The method according to claim 1, wherein: The initial stator resistance value is determined based on the sensor data and a stator reference temperature, and wherein the stator nonlinear resistance ratio curve is based on the stator reference temperature.

4. The method according to claim 1, wherein: The electric motor is a component of a vehicle propulsion system, wherein the stator resistance value is determined during operation of the propulsion system, and wherein the electric motor is a three-phase AC motor. 5 . The method of claim 1 , further comprising adjusting an operating parameter of the electric motor based on the stator resistance value.

6. A system comprising: An electric motor including a stator and a rotor; a sensor system including one or more sensors configured to generate sensor data indicative of sensed operating conditions of the electric motor including current magnitude, current angle, motor speed, stator temperature, and rotor temperature; as well as A controller operably coupled to the sensor system and the electric motor, the controller configured, via one or more processors: determining an initial stator resistance value based on a stator reference temperature and estimated data or sensor data received from a sensor system; determining a stator temperature coefficient based on the sensor data and a stator nonlinear resistance ratio curve; as well as The stator resistance value is determined based on the initial stator resistance value and the stator temperature coefficient.

7. The system according to claim 6, wherein: The stator reference temperature is a first reference temperature among a plurality of reference temperatures, wherein each of the plurality of reference temperatures is used to determine a corresponding calculated resistance value of the stator, wherein an error value between the calculated resistance value of the stator and a corresponding designed resistance value is determined at the plurality of reference temperatures, wherein the first reference temperature among the plurality of reference temperatures has a lowest error value.

8. The system according to claim 7, wherein: The calculated resistance value is based on a plurality of resistance values ​​at each of the plurality of reference temperatures and a temperature coefficient value at each of the plurality of reference temperatures, wherein the temperature coefficient value is defined by a non-linear resistance ratio curve.

9. The system according to claim 6, wherein: The initial stator resistance value is determined based on the sensor data and a stator reference temperature, and wherein the stator nonlinear resistance ratio curve is based on the stator reference temperature.

10. The system according to claim 6, wherein: The electric motor is a component of a vehicle propulsion system, wherein the stator resistance value is determined during operation of the propulsion system, wherein the electric motor is a three-phase AC motor, and wherein the controller is configured to adjust an operating parameter of the electric motor based on the stator resistance value via the one or more processors.

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