Method for determining temperature of electric machine

Abstract

The invention relates to a method for determining the temperature of an electric machine (100) having a rotor (110) and a stator (120), comprising the following steps: determining a first thermal calculation model modeling a thermal variable of the stator (120); determining a second thermal calculation model modeling a thermal variable of the rotor (110); determining a heat exchange between the rotor (110) and the stator (120) independently of one another in each case in the first thermal calculation model and in the second thermal calculation model; determining a temperature of the stator (120) by means of a first thermal calculation model; and determining the temperature of the rotor (110) by means of a second thermal calculation model.

Description

Technical Field

[0001] The present invention relates to a method for determining the temperature of an electric motor, as well as a computing unit and a computer program for implementing the method. Background Technology

[0002] For motor operation, it is meaningful to be able to determine the stator temperature as accurately as possible during operation, so as to monitor thermally critical components of the stator, such as the stator insulation, and to prevent damage. The more accurately the stator temperature can be determined, the closer the operation can be to the stator's thermal limit, and thus the more efficient or higher the motor's power can be.

[0003] Accordingly, it would be meaningful to determine the rotor temperature as accurately as possible. The component's temperature limit must also not be exceeded to prevent, for example, demagnetization of the permanent magnets or damage to the rotor windings.

[0004] For this purpose, for example, a thermal protection model can be calculated online (that is, during operation) in the software of the control equipment belonging to the power component of the motor (the so-called inverter). Summary of the Invention

[0005] Against this backdrop, a method for determining the temperature of an electric motor, along with a computing unit and a computer program for implementing the method, as described in the independent claims, is proposed. Advantageous designs are the subject of the dependent claims and the following description.

[0006] This invention employs the following approach: establishing thermal calculation models for the rotor and stator of the motor, where heat transfer from one model to the other need not be the same as heat transfer from the other model to the first model; that is, it does not require energy conservation to be obtained through both models. Therefore, instead of establishing a comprehensive thermal model of the motor including rotor and stator temperatures, two separate models are used, intentionally disrupting (intentionally disregarding) the energy balance between the rotor and stator. The resulting degrees of freedom significantly improve the model accuracy for rotor and stator temperatures. The apparent non-physical violation of energy conservation reflects the effect that heat flow can still (implicitly) be allowed to enter or leave the system of interest, heat flow that cannot or is only insufficiently mapped by a model with observable network parameters (model parameters).

[0007] In detail, a first thermal calculation model determines, provides, or uses a thermal calculation model of the stator, which models or maps the thermal parameters or thermal elements of the stator. This first thermal calculation model is also referred to below as the stator model. Furthermore, a second thermal calculation model determines, provides, or uses a thermal calculation model of the rotor, which models or maps the thermal parameters or thermal elements of the rotor. This second thermal calculation model is also referred to below as the rotor model. The heat exchange between the rotor and stator is determined, modeled, observed, or considered independently in both the first and second thermal calculation models.

[0008] At least one temperature of the stator (hereinafter referred to as stator temperature) is determined by means of a first thermal calculation model, and at least one temperature of the rotor (hereinafter referred to as rotor temperature) is determined by means of a second thermal calculation model.

[0009] The motor can be controlled based on the determined temperatures of the stator and rotor. By accurately understanding the stator and rotor temperatures, the motor can operate near the thermal limit temperatures of thermally critical components without exceeding these limits, thus preventing any danger or damage to the motor. Therefore, the effective power of the motor can be increased.

[0010] Within the scope of this invention, the actual heat exchange between the rotor and stator is modeled independently of each other in the stator and rotor models. The heat flow or energy flow between the stator and rotor is considered independently and not in a one-to-one relationship in the two computational models. Therefore, the heat exchange between the stator and rotor determined in the stator model does not necessarily correspond to the heat exchange determined in the rotor model. In particular, for both computational models, it is not assumed that the heat output from the stator to the rotor is automatically the same as the heat received by the rotor from the stator.

[0011] Traditionally, thermal calculation models of electric motors aim to model all energy flows between various model components as accurately as possible, assuming energy conservation within the model. For example, in such traditional models, the heat output from the stator to the rotor is automatically the same as the heat received by the rotor from the stator. However, this computational modeling approach places very high demands on understanding all heat flows present in the motor (including external disturbances). Consequently, the achievable accuracy of computational models in practice is often limited, and the models can become very large, leading to computational costs and difficulties in parameter identification.

[0012] The proposed approach allows for the dismantling of energy balance boundary conditions through an "open" system model, in which the system limits can be segmented closer to the stator while still adequately accounting for rotor effects through temperature boundary conditions. This method is particularly independent of the type of computational modeling used for the stator and rotor temperature models. For example, it can combine both data-based and physics-based computational models.

[0013] According to one implementation, the first and second thermal calculation models are not coupled or linked to each other through heat exchange between the rotor and stator as boundary conditions. Alternatively or supplementary, energy conservation between the first and second thermal calculation models regarding heat exchange between the rotor and stator is not assumed as a boundary condition. Therefore, these two calculation models are not physically precisely coordinated, but rather observed physically independently. Consequently, a precise understanding of all heat flows and external disturbances present in the motor is not required. Compared to using a physically precise overall model, the temperatures of the rotor and stator can be determined more accurately and less costly in this way using independent calculation models.

[0014] According to one embodiment, a first thermal calculation model has an interface or input port for the rotor temperature, and a second thermal calculation model has an interface or input port for the stator temperature. Specifically, these interfaces are configured as open interfaces for heat exchange between the rotor and stator. The stator model's interface, in particular, represents an open coupling with the outside of the rotor temperature, and the rotor model's interface, in particular, represents an open coupling with the outside of the stator temperature. Through these interfaces, heat transfer between the rotor and stator can be considered separately and independently in both calculation models. For example, the rotor temperature can be predetermined from the outside through the stator model's interface. For example, the rotor temperature determined by means of the rotor model can be transmitted to the stator model through this interface. Conversely, the stator temperature can be predetermined from the outside, for example, as the stator temperature determined by means of the stator model, through the rotor model's interface. The use of these open interfaces particularly allows for feasible schemes for openly or loosely coupling the two calculation models to each other.

[0015] According to one implementation, operating parameters of the motor are determined. Based on these determined operating parameters, the stator temperature is determined using a first thermal calculation model, and the rotor temperature is determined using a second thermal calculation model. For example, sensor values ​​can be acquired as such operating parameters during motor operation. Alternatively or supplementarily, the operating parameters can be determined based on the sensor values ​​acquired in this way. These operating parameters can, for example, describe one or more operating points of the motor, such as a first operating point with respect to the stator and a second operating point with respect to the rotor.

[0016] According to one embodiment, the thermal parameters of the stator are modeled in a first thermal calculation model and / or the thermal parameters of the rotor are modeled in a second thermal calculation model, respectively, based on torque and / or speed and / or phase current and / or intermediate circuit voltage and / or control frequency and / or the modulation method of the motor. Phase current, intermediate circuit voltage, control frequency, and modulation method are, in particular, electrical operating parameters of the inverter circuit used to control the motor. The control frequency can, in particular, be a carrier frequency for PWM-based control of power semiconductors. The modulation method can, in particular, be a control method such as space vector modulation (SVPWM), sinusoidal modulation, sinusoidal modulation with a third harmonic or triangular offset, flat-top, fundamental frequency clock, etc.

[0017] As an alternative or supplementary approach, according to one embodiment, the thermal parameters of the stator and / or rotor are modeled based on the temperature of the cooling fluid used to cool the stator and / or the volumetric flow rate of the cooling fluid used to cool the stator. This cooling fluid can be circulated, for example, through a cooling system used to cool the stator and can be, for example, cooling water or cooling air.

[0018] As an alternative or supplementary approach, according to one embodiment, the thermal parameters of the rotor are modeled based on the temperature of the cooling fluid used to cool the rotor and / or the volumetric flow rate of such cooling fluid. For example, such cooling fluid can be guided through the hollow shaft of the rotor as a fluid inside the rotor and can be, for example, cooling oil.

[0019] As an alternative or supplementary solution, in one implementation, the thermal parameters of the rotor are modeled accordingly based on the temperature of the transmission fluid. The transmission can be connected downstream of the motor to transmit the torque generated by the motor.

[0020] In one embodiment, a first thermal calculation model interdependently maps the thermal parameters of the stator body and the stator windings. In the motor, the stator windings are suitably arranged inside the stator body, for example, within slots inside the stator body. The stator windings can extend from the stator body on two axial sides, forming winding heads thereon. Therefore, by means of the stator model, the temperature of the stator body, especially the maximum temperature inside the stator body, and the temperature of the stator windings, especially the maximum temperature inside the stator windings, can be suitably determined. For example, a first hot spot or first hot node and a second hot spot or second hot node can be modeled in the stator model, wherein the first hot spot or first hot node maps to the stator windings and their maximum temperature, and the second hot spot or second hot node maps to the stator body and its maximum temperature. The thermal relationship or interaction between the stator body and the stator windings can be suitably modeled in the stator model, for example, as a relationship or connection between these two nodes.

[0021] In one embodiment, a first thermal calculation model models the temperature of the stator winding, the heat loss power of the stator winding, and / or the heat capacity of the stator winding as thermal parameters, interdependently. For example, a first node can interdependently map these three parameters of the stator winding. Alternatively or supplementarily, in one embodiment, the first thermal calculation model models the temperature of the stator body, the heat loss power of the stator body, and / or the heat capacity of the stator body, interdependently. For example, a second node can interdependently map these three thermal parameters of the stator winding. For example, the heat loss power and heat capacity of the stator winding and the heat loss power and heat capacity of the stator body can be modeled separately based on a first stator-related operating point of the motor, wherein this first operating point describes, for example, a combination of current values ​​for one or more of the following operating parameters: torque, speed, phase current, intermediate circuit voltage, control frequency, modulation method, temperature of the cooling fluid used to cool the stator, volumetric flow rate of the cooling fluid used to cool the stator, stator heat loss power, and rotor temperature. The heat capacity of the stator windings and stator body can be, for example, constant or variable depending on the current first operating point. For achievable accuracy, accurately determining the power losses of the stator body and stator windings is particularly crucial. These power losses are appropriately determined at each time step based on the current electrical and thermal operating point.

[0022] As an alternative or supplementary approach, according to one implementation, the first thermal calculation model models a variable thermal resistance, in particular, between the temperature of the stator windings and the temperature of the stator body. This thermal resistance, for example, can connect the first and second nodes to each other. This thermal resistance is determined, in particular, as a function of the first operating point.

[0023] As an alternative or supplementary approach, according to one implementation, the first thermal calculation model models the particularly variable thermal resistance between the rotor and stator, especially between the rotor temperature and the stator body temperature. The rotor temperature can, for example, be pre-defined as a boundary condition through an open interface. This thermal resistance can, for example, connect a second node with respect to the stator body to the rotor temperature boundary condition. For example, this thermal resistance is determined as a function of the motor speed and a first operating point.

[0024] As an alternative or supplementary approach, according to one embodiment, the first thermal calculation model interdependently models the temperature of the cooling fluid used to cool the stator, particularly as a boundary condition, and the particularly variable thermal resistance between the temperature of the stator body and the temperature of this cooling fluid. This thermal resistance, for example, can link a second node with respect to the stator body to the boundary condition with respect to the cooling fluid temperature. In particular, the first thermal resistance between the stator body temperature and the cooling fluid temperature can be modeled based on the operating parameters of the motor, and the second thermal resistance between the stator body temperature and the cooling fluid temperature can be modeled based on the operating parameters of the cooling fluid used to cool the stator or the entire cooling system. For example, this first thermal resistance between the stator body temperature and the cooling fluid temperature can be determined based on a first operating point, and the second thermal resistance between the stator body temperature and the cooling fluid temperature can be determined based on the volumetric flow rate of the cooling fluid used to cool the stator and / or based on the temperature of the cooling fluid used to cool the stator.

[0025] According to one embodiment, the stator winding within the slots of the stator body and the portion extending from the stator body in the form of a winding head can be modeled separately in the stator model. For this purpose, a first thermal calculation model can model the temperature, heat loss power, and / or heat capacity of the stator winding in the stator winding slots as thermal parameters, interdependently. For example, a first node can map these three parameters of the winding slots interdependently. Furthermore, the first thermal calculation model can model the temperature, heat loss power, and / or heat capacity of the stator winding head as thermal parameters, interdependently. For example, a second node can map these three parameters of the winding head interdependently. This method particularly improves the accuracy of the model because the stator winding losses can be separated into losses in the winding head and losses in the winding slots. The winding head losses and winding losses can then be fed into their respective nodes. As described above, the first thermal calculation model can also model the temperature, heat loss power, and heat capacity of the stator body interdependently, wherein a third node can map these three parameters. Furthermore, it is possible to model the thermal resistance between the temperature of the stator winding in the winding slot and the temperature of the stator body. This thermal resistance can be determined, for example, as a function dependent on the first operating point. Alternatively or supplementarily, it is possible to determine the thermal resistance between the temperature of the stator winding in the winding slot and the temperature of the winding head. This thermal resistance can also be determined, for example, as a function dependent on the first operating point. Furthermore, it is possible to model the thermal resistance between the temperature of the stator body and the temperature of the cooling fluid used to cool the stator.

[0026] In one implementation, the second thermal calculation model models the rotor temperature, rotor heat loss power, and / or rotor heat capacity as thermal parameters, interdependently. For example, the rotor temperature, heat loss power, and heat capacity can be mapped to the rotor nodes. For instance, the rotor heat loss power and heat capacity can be modeled separately based on a second operating point of the motor with respect to the rotor, where this second operating point describes a combination of current values ​​for one or more of the following operating parameters: torque, speed, phase current, intermediate circuit voltage, control frequency, modulation method, temperature of the cooling fluid used to cool the stator, volumetric flow rate of this cooling fluid used to cool the stator, temperature of the cooling fluid used to cool the rotor, volumetric flow rate of this cooling fluid used to cool the rotor, rotor heat loss power, stator temperature, and transmission oil temperature. The rotor heat capacity can, for example, have a constant value or can vary according to the current second operating point. Accurately determining the rotor heat loss power is particularly meaningful for achievable accuracy. The rotor heat loss power is suitably determined at each time step based on the current electrical and thermal operating points.

[0027] As an alternative or supplementary approach, according to one implementation, the second thermal calculation model models the particularly variable thermal resistance between the rotor and stator, especially between the rotor and stator temperatures. The stator temperature can be predetermined as a boundary condition through an open interface. For example, this thermal resistance can be determined as a function of the motor's speed and a second operating point.

[0028] As an alternative or supplementary approach, according to one implementation, the second thermal calculation model modeles, in a way that is interdependent, the temperature of the cooling fluid used to cool the stator and the particularly variable thermal resistance between the rotor and the cooling fluid used to cool the motor. This thermal resistance can be determined, in particular, as a function of rotational speed and a second operating point.

[0029] As an alternative or supplementary approach, in one embodiment, the second thermal calculation model modeles, in turn, the temperature of the cooling fluid used to cool the rotor, particularly inside the rotor, and the particularly variable thermal resistance between the rotor and the cooling fluid used to cool the rotor. This thermal resistance is determined, for example, as a function of the rotational speed, temperature, volumetric flow rate of the cooling fluid used to cool the rotor, and the second operating point.

[0030] As an alternative or supplementary approach, in one implementation, the second thermal calculation model models the temperature of the transmission fluid and the particularly variable thermal resistance between the rotor and the transmission fluid, in a manner that is interdependent. This thermal resistance is determined, for example, as a function of the rotational speed and the second operating point.

[0031] In one embodiment, the motor has a temperature sensor disposed at or within the stator. A first thermal calculation model then models the temperature of the temperature sensor and / or the thermal capacity of the temperature sensor as thermal parameters, interdependently. This thermal capacity of the temperature sensor can be a fixed value or can vary according to the first operating point explained above.

[0032] As an alternative or supplementary approach, in one implementation, the stator model models a particularly variable thermal resistance between the temperatures of the stator windings, the stator body, and the temperature sensor. This thermal resistance can, for example, be determined as a function of the rotational speed and the first operating point.

[0033] As an alternative or supplementary approach, in one implementation, the stator model models a particularly variable thermal resistance between the temperature of the cooling fluid used to cool the stator and the temperature of the temperature sensor. This thermal resistance can be determined, in particular, as a function of the rotational speed and the first operating point.

[0034] As an alternative or supplementary solution, according to one implementation, the stator model models the particularly variable thermal resistance between the temperature of the oil, especially the cooling oil used to cool the motor, and the temperature of the temperature sensor, wherein this thermal resistance can be determined as a function of the rotational speed, oil temperature, and first operating point.

[0035] Without using such a temperature sensor, a basic version of the stator model can be set up as a purely forward simulation. This sensorless approach may leave residual errors, which can be further reduced by extending the basic model using a stator temperature sensor. For example, in the stator model, various thermal parameters related to the temperature sensor can be bound to nodes related to the stator windings. With the stator temperature sensor, the accuracy of predicting stator hot spot temperatures can be improved by evaluating the deviation between the measured sensor temperature and the expected, modeled temperature, as well as by evaluating, for example, the weighted feedback to the stator model.

[0036] For example, for this purpose, Luenberger observation procedures, Kalman filters, and / or PI regulators can be used.

[0037] In one embodiment, the temperature sensor can also be modeled in the first thermal calculation model using two temperatures. For this purpose, the first thermal calculation model can model the first temperature and / or the second temperature and / or the first heat capacity and / or the second heat capacity of the temperature sensor as thermal parameters, interdependently. In this way, the temperature sensor can be mapped via two nodes to improve the model. Alternatively or supplementarily, in one embodiment, the stator model models a first thermal resistance between the temperature of the stator windings and the first temperature of the temperature sensor, and / or a second thermal resistance between the first temperature of the temperature sensor and the second temperature of the temperature sensor, and / or a third thermal resistance between the temperature of the cooling fluid used to cool the stator and the second temperature of the temperature sensor. These three thermal resistances can be determined, for example, as functions depending on the rotational speed and the first operating point.

[0038] In one embodiment, the motor has an oil cooling mechanism. In such an oil-cooled motor, also known as a wet motor, where oil is present in the rotor-stator gap, the stator and its windings are in direct contact with the oil. A first thermal calculation model then models, interdependently, the temperature of the oil in the oil cooling mechanism and the particularly variable thermal resistance between the oil temperature and the stator winding temperature as thermal parameters. This additional cooling path of the oil cooling mechanism can be mapped in the stator model, for example, by binding a first node of the stator winding to the oil temperature. The oil temperature can be provided, for example, by an oil temperature sensor or by an oil temperature model. If the stator temperature sensor is also in direct contact with the oil, this can be modeled by additional binding of the sensor node to the oil temperature. The thermal resistance between oil temperature and stator winding temperature depends particularly on the rotational speed and a third operating point, which specifically describes the current combination of torque, rotational speed, phase current, intermediate circuit voltage, control frequency, modulation method, cooling fluid temperature (for stator cooling), cooling fluid volumetric flow rate (for stator cooling), oil temperature, oil volumetric flow rate, stator power loss, and / or rotor temperature. In this case, feedback from sensor information, such as within the scope of the observation program scheme as mentioned above, can also improve the estimation of stator hot spot temperatures.

[0039] The current method is particularly suitable for use in the automotive field, such as in hybrid or electric vehicles. With this method, the temperature of the motor can be accurately determined and used, for example, during engine control.

[0040] The computing unit according to the invention, such as the control device of a motor vehicle, is particularly configured in terms of programming technology to implement the method according to the invention.

[0041] It is also advantageous to implement the method according to the invention in the form of a computer program or computer program product having program code for implementing all method steps, because this results in particularly low costs, especially when the control device used for execution is also used for other tasks and therefore already exists. Finally, a machine-readable storage medium is provided having the computer program as described above stored thereon. Suitable storage media or data carriers for providing the computer program, especially magnetic storage, optical storage and electrical storage, such as hard disks, flash drives, EEPROMs, DVDs, etc., can also download the program via computer networks (Internet, intranets, etc.). Here, such downloading can be performed in a wired or cable manner or wirelessly (e.g., via WLAN networks, 3G connections, 4G connections, 5G connections or 6G connections, etc.).

[0042] Other advantages and design solutions of the present invention are derived from the specification and drawings. Attached Figure Description

[0043] The present invention is schematically illustrated in the accompanying drawings by means of embodiments and is described below with reference to the accompanying drawings.

[0044] Figure 1 An electric motor is schematically shown, which can be the basis for one embodiment of the method according to the invention.

[0045] Figure 2 A thermal calculation model is schematically shown, which models the thermal parameters of the stator of an electric motor according to one embodiment of the method according to the present invention.

[0046] Figure 3 schematically illustrates the thermal calculation models, which model the thermal parameters of the motor stator according to one embodiment of the method of the present invention.

[0047] Figure 4 A thermal calculation model is schematically shown, which models the thermal parameters of the rotor of an electric motor according to one embodiment of the method of the present invention.

[0048] Figure 5 A temperature-time graph is schematically shown, which can be determined within the scope of one embodiment of the method according to the invention. Detailed Implementation

[0049] exist Figure 1 The electric motor is shown in a schematic cross-sectional view and is designated by 100. For example, the electric motor 100 can be used in a vehicle, such as a hybrid vehicle or an electric vehicle.

[0050] The motor 100 has a rotor 110 and a stator 120 surrounding the rotor 110, the rotor having a rotor body 112 arranged on a rotor shaft 111. The stator 120 has a stator body 121, and stator windings 122 are arranged in the stator body, particularly in the winding slots of the stator body 121. The stator windings 122 protrude on two axial sides of the stator body 121 and form winding heads 123 and 124 thereon, respectively. The stator body 121 can be made of iron or an iron alloy, such as steel or sheet metal, and can be configured, for example, as a plate assembly. The stator windings 122 can be made of, for example, copper or a copper alloy.

[0051] Temperature sensor 130, such as a heating conductor thermistor (NTC thermistor) with a negative temperature coefficient, is arranged on stator 120, for example in the winding head 124 of stator winding 122.

[0052] A cooling system 140 is provided to deliver one or more cooling fluids for cooling the rotor and / or stator and / or the entire motor 100. Such cooling fluids can be, for example, cooling water, cooling air, or cooling oil.

[0053] Control device 150, such as a vehicle motor control device, is configured to control motor 100 and may, for example, have an inverter circuit.

[0054] To accurately and reliably determine the temperatures of the rotor 110 and stator 120 during operation of the motor 100, the control device 150 is specifically designed, in terms of programming technology, to implement an embodiment of the method according to the invention. In this process, a first thermal calculation model for modeling the thermal parameters of the stator 120 and a second thermal calculation model for modeling the thermal parameters of the rotor 110 are implemented independently in the control device 150. These calculation models can be determined or created, for example, during the manufacturing or configuration of the motor 100 and are stored in the control device 150. During operation of the motor 100, the control device 150 determines the temperature of the stator 120 using the first thermal calculation model or the stator model and determines the temperature of the rotor 110 using the second thermal calculation model or the rotor model. Based on these determined temperatures, the control device 150 operates the motor 100, for example, such that the motor 100 can operate close to the thermal limit temperatures of the thermally critical components of the stator 120 and rotor 110 without causing danger or damage to the motor 100.

[0055] The following reference Figures 2 to 5 This explains the determination of independent stator and rotor models according to one embodiment of the present invention.

[0056] exist Figure 2 The stator model according to one embodiment of the method of the present invention is schematically shown and is indicated by 200.

[0057] The stator model 200 has an interface 230 for the temperature 240 of the rotor 110. This interface 230 represents an open interface for heat exchange between the rotor 110 and the stator 120, and an external, open coupling to the temperature 240 of the rotor 110. This interface allows heat exchange between the rotor 110 and the stator 120 to be considered without relying on the rotor model. For example, the rotor temperature 240 can be predetermined manually or externally, for example, as a result of the rotor model, via the interface 230.

[0058] In stator model 200, the thermal parameters of stator body 121 and stator winding 122 are mapped interdependently. For example, a first hot spot or first hot node 210 depicting stator winding 122 is modeled in stator model 200. For example, this first node 210 can be mapped interdependently to the temperature T of stator winding 122. 定子,Cu The heat loss power P of stator winding 122 v,定子,Cu The heat capacity C of stator winding 122 Cu .

[0059] Furthermore, a second hot spot or node 220 depicting the stator body 121 is modeled in the stator model 200. For example, this second node 220 can correlate with the temperature T of the stator body 121. 定子,Fe The heat loss power P of stator body 121 v,定子,Fe The heat capacity C of stator body 121 Fe .

[0060] For example, the heat loss power P of the stator winding 122 can be adjusted according to the first operating point associated with the stator 120. v,定子,Cu and heat capacity C Cu And the heat loss power P of stator body 121 v,定子,Fe and heat capacity C Fe Modeling is performed. This first operating point describes, for example, a combination of the current values ​​of torque, speed, phase current, intermediate circuit voltage, control frequency, modulation method, temperature of the cooling fluid used to cool stator 120, volumetric flow rate of the cooling fluid used to cool stator 120, power loss of stator 120, and temperature of rotor 110.

[0061] In stator model 200, a variable thermal resistance 211 is modeled between the temperature of stator winding 122 and the temperature of stator body 121, wherein this thermal resistance 211 connects the first node 210 and the second node 220 to each other. This thermal resistance 211 is determined as a function of the first operating point, R. Cu =h(Op1).

[0062] Furthermore, in the stator model 200, a variable thermal resistance 241 between the rotor 110 and the stator 120 is modeled, which, for example, connects the second node 220 and the rotor temperature 240 as boundary conditions. For instance, this thermal resistance 241 is determined as a function of the rotational speed of the motor 100 and the first operating point, R. Rot =f(n) Em Op1).

[0063] Furthermore, the stator model 200 models the temperature 250 of the cooling fluid used to cool the stator, as well as the first thermal resistance 251 and the second thermal resistance 252 between the temperature of the stator body 121 and the temperature 250 of the cooling fluid. This cooling fluid can be transported, for example, by means of a cooling system. These thermal resistances 251, 252 can serve as boundary conditions to connect the second node 220 to the temperature 250 of the cooling fluid. The first thermal resistance 251 can, for example, be determined as a function R depending on the first operating point. Fe1 =k(Op1). The second thermal resistance 252 can be determined, for example, as a function of the temperature and volumetric flow rate of the cooling fluid, R Fe2 =g(V') 冷却流体 T 冷却流体 ).

[0064] Stator model 200, for example, represents a basic version as a forward simulation, in which the temperature sensor 130 installed in stator 120 is not considered. This basic model can be extended using the stator temperature sensor 130, as shown below. Figures 3a to 3d As explained.

[0065] exist Figures 3a to 3d The stator model according to one embodiment of the method according to the invention is schematically shown in the figures, wherein in Figure 2 , 3a The same reference numerals in 3b, 3c and 3d denote the same or equivalent elements.

[0066] exist Figure 3a In this model, the extended stator model is denoted by 300. Furthermore, in stator model 300, thermal parameters related to temperature sensor 130 are modeled. Stator model 300 has another node 310 that depicts the temperature of temperature sensor 130. Additionally, the heat capacity 312 of temperature sensor 130 is modeled, for example, as a function dependent on a first operating point.

[0067] Furthermore, the stator model 300 models the variable thermal resistance 311 between the temperature of the stator winding 122, the temperature of the stator body 121, and the temperature of the temperature sensor 130. For example, the thermal resistance 311 can connect nodes 210 and 310 together and is determined, for example, as a function of rotational speed and the first operating point, R. Cu,传感器 =f(n) Em Op1).

[0068] Furthermore, in the extended stator model 300, a variable thermal resistance 321 is modeled between the temperature 250 of the cooling fluid used to cool the stator and the temperature 310 of the temperature sensor 130. This thermal resistance 321 can be determined, for example, as a function of the rotational speed and the first operating point, R.冷却剂,传感器 =f(n) Em， Op1) is used to determine this.

[0069] By using the stator temperature sensor 130, the accuracy of stator hot spot temperature prediction can be improved by evaluating the deviation between the measured sensor temperature and the expected, modeled temperature, as well as by evaluating the weighted feedback, for example, to the stator model 300. For this purpose, Luenberger observation procedures, Kalman filters, and / or PI controllers can be used.

[0070] Furthermore, the cooling system 140 can have an oil cooling mechanism for cooling the stator 100, wherein the extended stator model can also take into account the thermal parameters associated with this oil cooling mechanism, as shown in the following reference. Figure 3b As explained.

[0071] exist Figure 3b In this context, the implementation of the extended stator model is represented by 300'. For example, in... Figure 3b As shown, the oil temperature 340 is pre-defined as a boundary condition. A variable thermal resistance 341 is modeled between the oil temperature 340 and the stator winding temperature 210. For example, the cooling path of the oil cooling mechanism can be mapped in the stator model 300 by binding it to the first node 210. For example, the thermal resistance 341 between the oil temperature 340 and the stator winding temperature 210 can be determined as a function of rotational speed and another operating point, R. CuÖl =f(n) Em, Op3).

[0072] This other operating point describes, for example, the current combination of torque, speed, phase current, intermediate circuit voltage, control frequency, modulation method, cooling fluid temperature (for cooling stator 120), volumetric flow rate of cooling fluid for cooling stator 120, oil temperature, oil volumetric flow rate, stator loss power, and rotor temperature.

[0073] Furthermore, the stator model 300' has a variable thermal resistance 331 between the oil temperature 340 and the temperature 310 of the temperature sensor 130, for example as a function of rotational speed, oil temperature, and a first operating point, R. 油,传感器 =f(n) Em ,T 油 Op1).

[0074] To improve the model of the stator temperature sensor 130, the number of nodes in the sensor-sub-model can be increased, as shown below. Figure 3c As explained.

[0075] exist Figure 3cIn the extended stator model, the implementation is denoted by 300''. In stator model 300", a first node 350 and a second node 350 are provided instead of node 310 in model 300 or 300', respectively reflecting the temperature of temperature sensor 130. For example, the first node 350 can reflect a first temperature T of temperature sensor 130. 传感器1 Furthermore, the second node 350, for example, can reflect the second temperature T of the temperature sensor 130. 传感器2 Furthermore, in the stator model 300'', the first heat capacity 351 of the first node 350 and the second heat capacity 352 of the second node 360 ​​are modeled.

[0076] In addition, the stator model 300'' has a temperature of stator winding 122 and a first temperature T of temperature sensor 130. 传感器1 The first variable thermal resistance 353 between them is modeled. For example, this first thermal resistance 353 can connect nodes 210 and 350 to each other and is determined, for example, as a function of rotational speed and the first operating point, R. Cu,传感器1 =f(n) Em, Op1).

[0077] At the first temperature T of temperature sensor 130 传感器1 Second temperature T 传感器2 A second variable thermal resistance 354 is modeled, connecting nodes 350 and 360. This second variable thermal resistance 354 can be determined based on the rotational speed and the first operating point, R. 传感器1,传感器2 = f(n) Em Op1).

[0078] The temperature of the cooling fluid used to cool the stator is 250, and the second temperature T is measured by the temperature sensor 130. 传感器2 The third variable thermal resistance 355 is modeled. For example, this third variable thermal resistance 355 can be determined as a function of the rotational speed and the first operating point, R. 冷却剂,传感器2 =f(n) Em Op1).

[0079] For example, the accuracy of models 200, 300, 300', and 300'' can be further improved by separately observing the portion of the stator winding 122 within the slots of the stator body 120 and the portion of the stator winding 122 protruding beyond the stator body 120, i.e., the winding heads 123 and 124. Therefore, for example, the distribution of winding losses can be altered. For example, stator winding losses can be divided into losses in the winding heads and losses in the slots. Winding head loss P v,定子,Cu,绕组头 It can be fed into node 210. The slot loss P in the slot... v,定子,Cu,绕组槽It can be fed into node 220. From the knowledge of the corresponding node temperatures 210 and 220, the individual, temperature-dependent resistances in the winding heads 123 and 124 and in the slots can be determined and updated. Stator core loss P v,定子,Fe It can be additionally fed into node 220 as explained above.

[0080] However, to improve model accuracy, it is also conceivable to add another node and model the stator winding 122 using two nodes. This would allow the winding losses in the winding heads 123 and 124 and the losses in the slots to be better distributed to the nodes, as will be discussed below. Figure 3d As explained.

[0081] exist Figure 3d In this extended stator model, the implementation is denoted by 300'''. Compared to models 200, 300', and 300'', in this stator model 300''', the node 210 with respect to the stator winding 122 is replaced by two nodes 370 and 380, where node 370 maps to the stator winding 122 in the winding slot of the stator 120, and where node 380 maps to the winding heads 123, 124.

[0082] Nodes 370 interdependently map the temperature T of stator winding 122 in the winding slots. 定子,Cu,绕组槽 Heat loss power P v,定子,Cu,绕组槽 and heat capacity C Cu,绕组槽 Node 380 is interdependently mapped to the temperature T of winding heads 123 and 124. 定子,Cu,绕组头 Heat loss power P v,定子,Cu,绕组头 and heat capacity C Cu,绕组头 Therefore, the loss P in the winding head v,定子,Cu,绕组头 and the loss P in the tank v,定子,Cu,绕组头 It can be directly assigned to nodes 370 and 380. Stator core loss P v,定子,Fe As explained above, it is fed into node 220.

[0083] Furthermore, in stator model 300''', the variable thermal resistance 371 between node 220 with respect to stator body 121 and node 370 with respect to winding slot is modeled. This thermal resistance 371 can be determined as a function of the first operating point, R 节点220,370 =f(Op1).

[0084] Another variable thermal resistance 372 is provided between node 370 with respect to the winding slot and node 380 with respect to the winding head. This thermal resistance 372 can also be determined as a function of the first operating point, R. 节点370,380 =f(Op1).

[0085] As in Figure 3d As shown, a direct connection can also be established between node 380 and resistor 353. This should be understood in particular as the ability to implement the sensor path symbolically represented by nodes 350 and 360 via either node 370 or node 380, especially depending on the sensor's mounting location and whether a two-node model symbolically represented by nodes 220 and 370 or a three-node model symbolically represented by nodes 220, 370, and 380 should be used to depict the stator hotspot temperature.

[0086] It goes without saying that, as explained here regarding model 300'', the scheme of replacing node 210 of stator winding 122 with two nodes 370 and 380 regarding winding slots and winding heads can also be applied to stator models 200, 300 and 300' in a corresponding manner.

[0087] exist Figure 4 The image schematically illustrates a rotor model according to one embodiment of the method of the present invention, and it is indicated by 400.

[0088] Rotor model 400 is determined independently of stator models 200 or 300. In rotor model 400, heat exchange between rotor 110 and stator 120 is considered without regard to heat exchange in stator models 200 or 300. Stator models 200, 300, and rotor model 400 are not connected via heat exchange between rotor 110 and stator 120. No assumption is made regarding energy conservation in relation to heat exchange between rotor 110 and stator 120 among stator models 200, 300, and rotor model 400.

[0089] According to stator model 200 or 300, rotor model 400 has an interface 420 for a temperature 430 of stator 120, wherein this interface 420 represents an open interface for heat exchange between rotor 110 and stator 120 and an open coupling to the external temperature 430 of stator 120. Heat exchange between rotor 110 and stator 120 can be considered in rotor model 400 through this interface 420 without depending on stator models 200 or 300. For example, the stator temperature 430 can be manually or pre-given externally through interface 420, for example, as a result of stator models 200 or 300.

[0090] In rotor model 400, the temperature 410, heat capacity 411, and heat loss 412 of rotor 110 are modeled. For example, this temperature T of rotor 110 can be modeled. 转子 This heat capacity C 转子 And this heat loss P v,转子This is mapped onto nodes or hot spots for rotor 110. For example, the heat loss power 412 and heat capacity 411 of rotor 110 can be modeled based on a second operating point associated with rotor 110, where the second operating point describes a combination of current values ​​for torque, speed, phase current, intermediate circuit voltage, control frequency, modulation method, temperature of the cooling fluid used to cool stator 100, volumetric flow rate of the cooling fluid used to cool stator 100, temperature of the cooling fluid used to cool rotor 110, volumetric flow rate of the cooling fluid used to cool rotor 110, power loss of rotor 110, temperature of stator 120, and temperature of transmission oil.

[0091] Rotor model 420 also has a variable thermal resistance 431 located between rotor 110 and stator 120 or between temperature 410 of rotor 110 and temperature 430 of stator 120, wherein this thermal resistance 431 can be determined based on the speed of motor 100 and a second operating point. 定子 (n) Em Op2).

[0092] Furthermore, in the rotor model 420, the temperature 450 of the cooling fluid used to cool the stator 100, the temperature 460 of the cooling fluid used to cool the rotor 110, and the temperature 470 of the transmission oil are modeled as boundary conditions. The variable thermal resistance 451 between the temperature 410 of the rotor 110 and the temperature 450 of the cooling fluid used to cool the stator 100, the variable thermal resistance 461 between the temperature 410 of the rotor 110 and the temperature 460 of the cooling fluid used to cool the rotor 110, and the variable thermal resistance 471 between the temperature 410 of the rotor 110 and the temperature 470 of the transmission oil are also modeled.

[0093] The thermal resistance 451 of the cooling fluid at temperature 450 can be determined based on the rotational speed and the second operating point. 电机冷却剂 (n) Em Op2). The thermal resistance 461 of the cooling fluid inside the rotor at temperature 460°C can be determined based on the rotational speed, temperature, volumetric flow rate of the cooling fluid inside the rotor, and the second operating point. 转子内部冷却剂 (n) Em T 转子内部冷却剂 The thermal resistance of the transmission fluid at temperature 470°C and temperature 471°C can be determined based on the engine speed and the second operating point. 变速器油 (n) Em Op2).

[0094] By using two separate, independent computational models for the stator 120 and rotor 110, which intentionally disrupt or disregard the energy balance between the rotor 110 and stator 120, the temperatures of the rotor 120 and stator 110 can be modeled and determined more accurately than by using a single, physically accurate thermal model of the motor 100 that maps the heat exchange between the rotor and stator. This is achieved through methods such as... Figure 5 As explained.

[0095] Figure 5 A temperature graph 500 is schematically shown, plotted over time.

[0096] Curve 510 represents the time-varying curve of the maximum stator temperature or stator hot spot temperature actually measured during the operation of motor 100 on the test bench.

[0097] Curve 520 represents the corresponding stator temperature determined by means of a stator model 200 according to one embodiment of the invention, which is implemented on the control device 150 during operation of the motor 100.

[0098] Curve 530 represents the time-varying temperature of the cooling fluid used to cool the stator 120.

[0099] As in Figure 5 As can be seen, the stator temperature can be simulated relatively accurately using the stator model 200.

Claims

1. A method for determining the temperature of an electric motor (100) having a rotor (110) and a stator (120), the method comprising the steps of: A first thermal calculation model (200, 300, 300', 300'', 300''') is determined to model the thermal parameters of the stator (120); A second thermal calculation model (400) is determined to model the thermal parameters of the rotor (110). The heat exchange between the rotor (110) and the stator (120) is determined independently of each other in the first thermal calculation model (200, 300, 300', 300'', 300''') and in the second thermal calculation model (400); The temperature of the stator (120) is determined using a first thermal calculation model (200, 300, 300', 300'', 300'''). The temperature of the rotor (110) is determined by means of a second thermal calculation model.

2. The method according to claim 1, wherein with respect to the heat exchange between the rotor (110) and the stator (120), no energy conservation is assumed between the first thermal calculation model (200, 300, 300', 300'', 300''') and the second thermal calculation model (400).

3. The method according to claim 1 or 2, wherein the first thermal calculation model (200, 300, 300', 300'', 300''') has an interface (230) for the temperature (240) of the rotor (110), and wherein the second thermal calculation model (400) has an interface (430) for the temperature (420) of the stator (120).

4. The method according to any one of the preceding claims, wherein the method further comprises the following steps: Determine the operating parameters of the motor (100); The temperature of the stator (120) is determined based on the determined operating parameters using the first thermal calculation model (200, 300, 300', 300'', 300'''). and The temperature of the rotor (110) is determined based on the determined operating parameters using a second thermal calculation model (400).

5. The method according to any one of the preceding claims, wherein the thermal parameters of the stator (120) are modeled in a first thermal calculation model (200, 300, 300', 300'', 300''') and / or the thermal parameters of the rotor (110) are modeled in a second thermal calculation model (400) based on one or more of the following operating parameters: The torque of the motor (100); The rotational speed of the motor (100); Phase current of motor (100); The intermediate circuit voltage of the motor (100); The operating frequency of the motor (100); Modulation method of motor (100); The temperature of the cooling fluid used to cool the stator (120); Volumetric flow rate of the cooling fluid used to cool the stator (120); The temperature of the cooling fluid used to cool the rotor (110); The volumetric flow rate of the cooling fluid used to cool the rotor (110); The temperature of the transmission fluid.

6. The method according to any one of the preceding claims, wherein the first thermal calculation models (200, 300) map the thermal parameters of the stator body (121) and the thermal parameters of the stator windings (122) of the stator (120) in a mutually dependent manner.

7. The method according to any one of the preceding claims, wherein the first thermal calculation models (200, 300, 300', 300'') model one or more thermal parameters dependently on each other: Temperature (210) of the stator winding (122) of the stator (120); The heat loss power of the stator winding (122) (210); The heat capacity of the stator winding (122) is (210); Temperature (220) of stator body (121) of stator (120); The heat loss power of the stator body (121) (220); The heat capacity of the stator body (121) is (220); Thermal resistance (211) between the temperature (210) of the stator winding (122) and the temperature (220) of the stator body (121); Thermal resistance (241) between rotor (110) and stator (120); The temperature (250) of the cooling fluid used to cool the stator (120); and Thermal resistance (251, 252) between the temperature (220) of the stator body (121) and the temperature (250) of the cooling fluid used to cool the stator (120).

8. The method according to any one of claims 1 to 6, wherein the first thermal calculation model (300''') modeles one or more thermal parameters dependently on each other: Temperature of the stator winding (122) in the winding slot of the stator (120) (370); The heat loss power (370) of the stator winding (122) in the winding slot of the stator (120); The heat capacity (370) of the stator winding (122) in the winding slot of the stator (120). Temperature (380) of the winding ends (123, 124) of the stator (120); The heat loss power (380) of the winding heads (123, 124) of the stator (120). The heat capacity (380) of the winding heads (123, 124) of the stator (120); Temperature (220) of stator body (121) of stator (120); The heat loss power of the stator body (121) (220); The heat capacity of the stator body (121) is (220); Thermal resistance (371) between the temperature (370) of the stator winding (122) in the winding slot of the stator (120) and the temperature (220) of the stator body (121); Thermal resistance (372) between the temperature (370) of the stator winding (122) in the winding slot of the stator (120) and the temperature (380) of the winding head (123, 124) of the stator (120). Thermal resistance (241) between rotor (110) and stator (120); The temperature (250) of the cooling fluid used to cool the stator (120); and Thermal resistance (251, 252) between the temperature (220) of the stator body (121) and the temperature (250) of the cooling fluid used to cool the stator (120).

9. The method according to any one of the preceding claims, wherein the second thermal calculation model (400) modeles one or more of the following thermal parameters in a mutually dependent manner: The temperature of the rotor (110) is 410. The heat loss power of the rotor (110) is (412). The heat capacity of the rotor (110) is (411). Thermal resistance (431) between rotor (110) and stator (120) The temperature of the cooling fluid used to cool the stator (100) is (450). Thermal resistance (451) between the rotor (110) and the cooling fluid used to cool the stator (100). The temperature (460) of the cooling fluid used to cool the rotor (110). Thermal resistance (461) between the rotor (110) and the cooling fluid used to cool the rotor (110). Transmission fluid temperature (470); Thermal resistance (471) between the rotor (110) and the transmission fluid.

10. The method according to any one of the preceding claims, wherein the motor (100) has a temperature sensor (130) disposed at or within the stator (120), wherein the first thermal calculation model (300, 300') modeles one or more thermal parameters dependently on each other: Temperature (310) of temperature sensor (130); The thermal capacity (312) of the temperature sensor (130); The thermal resistance (311) between the temperature of the stator winding (122), the temperature of the stator body (121), and the temperature of the temperature sensor (130) (310); The temperature (250) of the cooling fluid used to cool the stator (120); The thermal resistance (321) between the temperature (250) of the cooling fluid used to cool the stator (120) and the temperature (310) of the temperature sensor (130). The temperature of the oil is 340°C. The thermal resistance (331) between the temperature of the oil (340) and the temperature of the temperature sensor (130) (310).

11. The method according to any one of claims 1 to 9, wherein the motor (100) has a temperature sensor (130) disposed at or within the stator (120), wherein the first thermal calculation model (300'', 300''') modeles one or more thermal parameters dependently on each other: The first temperature (350) of the temperature sensor (130); The second temperature (360) of the temperature sensor (130); The first thermal capacity (351) of the temperature sensor (130); The second thermal capacity (352) of the temperature sensor (130); The first thermal resistance (353) between the temperature of the stator winding (122) and the first temperature (350) of the temperature sensor (130); The second thermal resistance (354) between the first temperature (350) and the second temperature (360) of the temperature sensor (130); The temperature (250) of the cooling fluid used to cool the stator (120); The third thermal resistance (355) between the temperature (250) of the cooling fluid used to cool the stator (120) and the second temperature (360) of the temperature sensor (130).

12. The method according to any one of the preceding claims, wherein the motor (100) has an oil cooling mechanism, and wherein the first thermal calculation model (300') models one or more thermal parameters dependently on each other: The temperature of the oil in the oil cooling system is 340°C. Thermal resistance (341) between the temperature (340) of the oil in the oil cooling mechanism and the temperature (210) of the stator winding (122).

13. A computing unit (150) configured to implement all method steps of the method according to any one of the preceding claims.

14. A computer program that, when executed on a computing unit (150), causes the computing unit (150) to perform all the method steps of the method according to any one of claims 1 to 12.

15. A machine-readable storage medium having a computer program, as described in claim 14, stored thereon.

Images