Temperature estimation model and method for electrical generator

Abstract

To provide a method and a corresponding arrangement for temperature estimation of a permanent magnet synchronous electrical generator, where temperature estimation is improved and / or the accuracy is enhanced for generator components or portions which exhibit a temperature gradient across their dimension or extent.SOLUTION: The invention provides a method of temperature estimation of an electrical generator including a rotor and a stator, which has teeth and windings. The method includes: forming a thermal model for the generator including multiple elementary thermal modeling elements (322) partially connected to each other in a network for modeling heat conduction, where at least one elementary thermal modeling element (322) includes first and second error compensation thermal resistances (R_m1, R_m2) connected in series between a star point (324) and a heat providing and / or absorbing system (326); estimating temperatures for the multiple elementary modeling elements by feeding multiple values of the operational parameters into the thermal model; and modeling heat transfers according to connectivity and thermal resistance within the network and within the elementary thermal modeling elements.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates in particular to a method and a corresponding device for temperature estimation of a permanent magnet synchronous electric generator. Furthermore, the present invention relates to a method and a corresponding controller for controlling an electric generator and thereby applying a temperature estimation model and / or method. Furthermore, the present invention relates to a wind turbine.

[0002] Background technology In direct drive (DD) permanent magnet (PM) wind turbine generators, higher torque density leads to higher wind turbine (WT) output power, but it can also lead to higher operating temperatures due to losses, limiting power capability due to irreversible PM demagnetization. Additionally, high generated temperatures can significantly impact machine life, especially for the most vulnerable generator components, such as the stator winding insulation and PM. More specifically, the life of the winding insulation is significantly affected by the temperature of the stator winding. Therefore, the life of the winding insulation is particularly important and decreases significantly when the temperature exceeds the manufacturer's specified temperature. Furthermore, irreversible partial demagnetization can become another problem when the PM temperature exceeds its maximum allowable temperature.

[0003] As a result, high winding and magnet temperatures shorten the lifespan of generator components, resulting in reduced generator efficiency, power density, and reliability. Therefore, their temperature information, especially hot spot temperatures, is important to ensure safe and reliable operation under normal and overload conditions (e.g., power boost).

[0004] Winding and PM temperatures can be measured by thermal sensors, but winding components typically have large temperature gradients that are sensitive to the location of the installed thermal sensors, so a single or a few thermal sensors may inadequately measure spatial temperature variations and hot spot temperatures. Installing thermal sensors increases costs, both in terms of installation and maintenance. An array of thermal sensors also increases the number of connection channels between the generator and the controller, which has a detrimental effect on system reliability.

[0005] To date, sensorless temperature estimation in generators relies on two mainstreams: electrical parameter identification-based methods and thermal model-based methods.

[0006] First, electrical parameter identification-based methods estimate the overall average winding temperature and PM temperature by utilizing the temperature dependence of winding resistance (approximately 0.4% / °C) and / or PM flux linkage (approximately -0.1% / °C). However, electrical parameter identification methods have several drawbacks. 1) Due to the rank deficiency problem, identification methods typically require additional injected perturbation signals, such as current and position offsets, which adversely affect system stability. 2) The reflected temperatures of winding resistance and PM flux linkage are sensitive to measurement errors due to their low temperature coefficients and manufacturing tolerances and imperfections. On the other hand, although hot spot temperatures are more critical, they can still be much lower than the corresponding hot spot temperatures.

[0007] Second, thermal model-based methods are developed based on the heat transfer theorem to describe the thermal behavior of a system. However, due to inappropriate assumptions in existing thermal models, i.e., either "I-type" or "T-type" networks, significant deviations can exist in both average and hot spot temperature estimations. As a result, they may not be suitable to substitute for the function of thermal sensors due to low estimation accuracy, especially for components with large temperature gradients, such as windings.

[0008] U.S. Patent Application Publication No. 2012226483 discloses motor temperature estimation based on a thermal model. A vehicle includes a power source, a motor, and a computing device. The power source supplies electric energy to the motor, and the motor generates rotational motion from the received electric energy. The computing device is configured to estimate the temperature of the motor in real time based at least in part on a thermal model of the motor. The thermal model includes a plurality of nodes and at least one thermal resistance. Each node represents an area of ​​the motor, and each thermal resistance represents a heat transfer path between at least two of the nodes. The method includes solving one or more energy balance equations to determine a temperature change at each node, and estimating the temperature of the motor in real time based at least in part on at least one of the temperature change at each node and the thermal resistance in the thermal model.

[0009] U.S. Patent Application Publication No. 2019114385 discloses a kinetic thermal analysis method using a temperature field directly connected to a thermal circuit. A motor thermal analysis method in which the temperature field is directly connected to the thermal circuit is used to model some motor components, while a thermal circuit method is used to model other components. The temperature field contacts the thermal circuit via an equivalent temperature boundary and an equivalent convection boundary. The thermal circuit section is composed of one-dimensional finite elements, and two connecting boundaries are defined as two boundary elements. The element stiffness matrix, element load matrix, and element mass matrix corresponding to the one-dimensional finite elements and boundary elements are superimposed on the global stiffness matrix, global load matrix, and global mass matrix, respectively, and simultaneous linear equations are solved to simultaneously determine the temperature distribution of the temperature field and the temperature distribution of the thermal circuit.

[0010] U.S. Patent Application Publication No. 2020341062 discloses a system and method for estimating temperature and heat loss in an electric motor. The system for thermal management of an electric motor uses an extended thermal circuit model of the electric motor, which relates temperatures of a set of nodes of the thermal circuit model to temperature measurements at a first subset of nodes and heat losses of heat sources at a second subset of nodes for joint estimation of temperatures at the entire set of nodes and heat loss values ​​at a second subset of nodes. The system solves the joint estimation using an estimator / observer. The system outputs one or a combination of temperature values ​​and heat loss values ​​for the set of nodes.

[0011] However, it has been observed that conventional methods for generator temperature estimation do not provide accurate estimates of the temperature of certain generator components in all situations or under all conditions, especially those that have substantial temperature gradients.

[0012] Therefore, there may be a need for a method and corresponding apparatus for temperature estimation of a permanent magnet synchronous electric generator that can improve and / or increase the accuracy of temperature estimation, particularly for generator components or portions that may exhibit substantial temperature gradients across respective dimensions or ranges.

[0013] Summary of the Invention According to one embodiment of the present invention, there is provided a method of temperature estimation for an electric generator including a plurality of generator components comprising a rotor and a stator having teeth and windings, the method comprising receiving (e.g., measured) values ​​of electrical and / or mechanical operating parameters of the generator, and using a thermal model, particularly including software or implemented in software, for the generator comprising a plurality of basic thermal modeling elements partially connected to each other in a network for modeling heat transfer, each generator component being modeled by one or more of the plurality of basic thermal modeling elements, at least one basic thermal modeling element being configured to calculate a thermal transfer coefficient between respective portions of the generator components for each of a plurality of directions. a thermal model comprising two conductive thermal resistors that model resistance in opposite directions toward their boundaries, a star point connected to a plurality of (e.g., three) midpoints between each of the two conductive thermal resistors, a heat supply and / or absorption system that models a heat source and / or heat sink, and first and second error-compensating thermal resistors connected in series between the star point and the heat supply and / or absorption system, the method including estimating a plurality of values ​​of temperatures of a plurality of basic modeling elements by supplying a plurality of values ​​of operating parameters to the thermal model, and modeling heat transfer between and within a plurality of generator components or parts according to the connectivity and thermal resistances within the network and within the basic thermal modeling elements.

[0014] The generator may provide AC power in multiple phases, for example, three or more phases. The rotor may be an outer rotor or an inner rotor.

[0015] The generator may be a permanent magnet synchronous electric generator including a rotor with permanent magnets. In other embodiments, the generator may be an electrically excited asynchronous electric generator or a doubly-fed induction machine.

[0016] The permanent magnets may be mounted to an outer rotor housing, which may be rotatably supported by bearings relative to the stator, for example, to enable rotation of the rotor relative to the stator. The stator may be a single-segment or multi-segment stator. The stator may have one multi-phase winding set or multiple multi-phase winding sets. Each winding set, for example, a three-phase winding set, may be connected to a respective converter, including, among other things, an AC / DC converter portion, a DC link, and a DC / AC converter portion. The converter may thereby be configured to convert a variable frequency AC power stream into a fixed frequency AC power stream, which may then be supplied to a utility grid.

[0017] The method may be implemented in software and / or hardware and may, for example, be performed by the generator controller or a processing portion separate from the generator controller.

[0018] The electrical and / or mechanical operating parameters of the generator may include, for example, current measurements and / or rotational speed and / or coolant and ambient temperatures of the generator. The generator operating parameters may be measured or estimated from other quantities related to the performance or operation of the generator, for example.

[0019] The thermal model may include, or be implemented or represented in, software and / or hardware, among others, and includes a software model.

[0020] The thermal model may be implemented, for example, as an electrical circuit including respective thermal resistances within basic thermal modeling elements partially connected to one another, each of which may itself have multiple conductive thermal resistances and, as specified, first and second error-compensating thermal resistances.

[0021] The model can simulate heat flow in and through multiple generator components or generator component portions according to the spatial arrangement and connections between multiple basic thermal modeling elements, and within each of the basic thermal modeling elements, heat flow is modeled according to a respective (3×2) conduction thermal resistance and first and second error-compensation thermal resistances.

[0022] For each generator component, e.g., rotor housing, permanent magnet, winding, stator laminations, or stator teeth, one or more basic thermal modeling elements may be utilized, e.g., to model different spatial portions of the respective generator component. The number of basic thermal modeling elements for modeling a generator component or a portion of a generator component may be selected according to the desired accuracy of the temperature estimation and / or depending on the available computing resources.

[0023] The thermal model may include, inter alia, multiple thermal model segments, each corresponding to a respective axial region or axial position. Due to the substantial cylindrical symmetry of the generator, the thermal model segments may be substantially similar to one another. This may simplify the implementation or configuration of the thermal model.

[0024] The conductive thermal resistance within a particular basic thermal modeling element that models a particular generator component or generator component portion may be based on or derived from the geometry and / or material and / or extent of the respective generator component or generator component portion within the modeled spatial domain. The same may be true for the first and second error-compensating thermal resistances.

[0025] It should also be appreciated that the respective conductive thermal resistances and / or the first and second error-compensating thermal resistances may be determined based on calibration data including measured temperatures and / or average temperatures and / or hot spot temperatures at the boundaries of the respective generator component or generator component portion. Thus, the respective conductive thermal resistances and the first and second error-compensating thermal resistances of each of the basic thermal modeling elements may represent adjustable model parameters that may have been previously determined or calculated based on, for example, construction details such as the material, dimensions and / or geometry and / or shape of the considered component and / or based on measured temperatures.

[0026] Providing first and second error-compensating thermal resistances within at least one of the basic thermal modeling elements (or all of the basic thermal modeling elements) may enable more accurate characterization or determination of the temperature (distribution) within the generator component or generator component portion. In particular, the first and second error-compensating thermal resistances may enable accurate estimation of the average temperature and hot spot temperature (maximum temperature of the component or component portion modeled by the considered basic thermal modeling element) of each generator component or generator component portion being modeled by the considered basic thermal modeling element.

[0027] Conventional thermal models may not be able to determine the average temperature as well as the hot spot temperature of the generator component or component portion being considered. If both the average temperature and the maximum temperature of a particular generator component portion or component can be estimated, the generator can be controlled in an improved manner and can be diagnosed in an improved manner.

[0028] The heat supply and / or absorption system may, for example, make it possible to model the heat storage due to the specific heat storage capacity of the generator part or generator component considered. Furthermore, it may also model the heat generation that may occur, for example, in the windings or winding coils. The heat supply and / or absorption system may also make it possible to model the loss input and heat capacity of different generator components or component parts.

[0029] According to one embodiment of the present invention, the temperature value estimated between the first error compensation resistor and the second error compensation resistor is considered as a midpoint temperature (e.g., theta_mid), which may be the maximum temperature (rise) caused by internal loss generation.

[0030] The maximum temperature (rise) may be a spatially related value and may be defined as the maximum temperature across the component. The midpoint temperature may be the temperature at the center / middle of the component or component part being modeled.

[0031] Additionally, other temperature values ​​estimated between the second error compensation resistor and the heat supply and / or absorption system are considered to be the average temperature of the respective component or portion (e.g., spatially averaged over the component or component portion modeled by this basic thermal modeling element) (e.g., theta_avg).

[0032] Each basic thermal modeling element may be implemented with or comprise a circuit of connected thermal resistors. In particular, two conductive thermal resistors may be connected in series in each of multiple directions, for example, in three directions. The midpoints of the three pairs of series-connected conductive thermal resistors may be connected to each other at a star point. The series-connected first and second error-compensating thermal resistors are also connected to the star point. Furthermore, the first error-compensating thermal resistor, the second error-compensating thermal resistor, and the heat supply and / or absorption system are connected in series to the star point. The first and second error-compensating thermal resistors are thereby connected to each other, and the temperature estimated between these two compensation thermal resistors is considered the hot spot temperature of the respective generator component or generator component portion modeled by the considered basic thermal modeling element.

[0033] In the absence of internal heat generation, the temperature estimated at the star point can physically represent the spatial midpoint temperature. However, if the system has a heat supply system, all heat is assumed to be concentrated at the spatial midpoint (spatial or geometric center) rather than actually distributed throughout the solid. As a result, the estimated temperature at the star point is overestimated. Therefore, the first compensation thermal resistance is obtained based on the multidimensional conduction heat transfer equation to compensate for the estimated temperature difference from the star point to the actual midpoint temperature.

[0034] Therefore, the temperature estimated between those two compensation thermal resistances is the maximum temperature rise caused by internal heating and can in most cases be considered the maximum temperature (of the modeled component or component part).

[0035] This allows the most critical areas or temperatures within the modeled generator section to be identified.

[0036] According to one embodiment of the present invention, the temperature value determined between the second error compensation resistor and the heat supply and / or absorption system is considered to be the average temperature (e.g., theta_avg) of the respective component or component portion.

[0037] The second error compensation resistor is in the considered basic thermal modeling element connected to the heat supply and / or absorption system, and the temperature determined between the second error compensation resistor and the heat supply and / or absorption system is considered to be the average temperature of the respective component or component part being modeled by the considered basic thermal modeling element.

[0038] A second compensating thermal resistance is used to represent the temperature drop between the actual midpoint temperature and the average temperature, which can be determined analytically by solving the multidimensional conduction heat transfer equation.

[0039] The average temperature of each component or component portion can correspond, for example, to the spatially averaged (mean) temperature of the component or component portion, thereby obtaining an overall or average temperature of the modeled component, which can be useful for diagnosing the condition of the respective component.

[0040] According to one embodiment of the present invention, both the maximum temperature as well as the average temperature of each component or component portion are estimated by the method.

[0041] Conventional thermal modeling methods may not provide the maximum temperature as well as the average temperature of each component or component part. When both of these temperature values ​​are available, improved diagnostics and / or control of the generator may be provided and / or a lifespan estimate may be provided.

[0042] According to one embodiment of the present invention, the first and / or second error compensation resistances are calculated as a sum of multiple products of sine functions, in particular over multiple (nodal) indices for three directions, based on the material and / or dimensions and / or volume and / or equivalent resistance taking into account parallel conduction and / or eigenvalues ​​in multiple directions of the component or component part.

[0043] Each power compensation resistor may be derived from the characteristics of each modeled generator component or generator component portion.

[0044] According to one embodiment of the present invention, each generator component in each of the plurality of spatial regions is modeled by one or more of a plurality of basic thermal modeling elements, each basic thermal modeling element being associated with boundary temperature values ​​and bulk temperature values ​​in a plurality of directions, and the thermal connections of the plurality of generator components or component portions being modeled by heat transfer between boundaries of respective adjacent or neighboring basic thermal network elements.

[0045] The basic thermal modeling elements are connected to one another according to the spatial arrangement or location of each modeled generator component or generator component portion.

[0046] The estimated temperatures at each end of two series-connected conductive thermal resistances (for each of multiple directions) can correspond to the temperatures at the boundaries of each modeled generator component in each direction.

[0047] Due to the low thermal conductivity of the winding insulation and permanent magnets, internal heat generation causes heat concentration within the solid, with the maximum temperature rise occurring at the spatial midpoint. Therefore, the estimated midpoint temperature is representative of the hot spot temperature. In comparison, the scenario where the boundary temperature is the hot spot temperature rarely occurs when a permanent magnet machine is operating.

[0048] The hot spot temperature may correspond to the highest estimated temperature across the modeled generator component or portion of the generator component.

[0049] According to one embodiment of the present invention, estimating the plurality of values ​​of temperature comprises applying the heat transfer theorem or the energy conservation theorem to the model, and / or estimating the plurality of values ​​of temperature is performed sensorlessly without measuring any temperature of the generator except for the cooling fluid temperature, and / or estimating the plurality of values ​​of temperature is performed in real time during operation of the generator, and / or comprises estimating generator losses based on the estimated temperature values, and / or estimating wear and / or life of a component or component part based on the estimated temperature values, and / or diagnosing failure of a component or component part based on the estimated temperature values.

[0050] The model may thereby be implemented using one or more physical laws of heat transfer, which may in turn allow the method to be advantageously utilized for downstream purposes such as control and / or diagnostics.

[0051] According to one embodiment of the present invention, for each basic thermal modeling element, the following applies: in a first direction, two first conductive thermal resistances connected in series are provided; in a second direction, two second conductive thermal resistances connected in series are provided; in a third direction, two third conductive thermal resistances connected in series are provided; a point between the two first conductive thermal resistances connected in series is connected to a star point; a point between the two second conductive thermal resistances connected in series is connected to a star point; a point between the two third conductive thermal resistances connected in series is connected to a star point; the temperatures at the two ends of the two first conductive thermal resistances connected in series are related to the boundary temperature of the respective basic thermal modeling element according to the first direction; the temperatures at the two ends of the two second conductive thermal resistances connected in series are related to the boundary temperature of the respective basic thermal modeling element according to the second direction; and the temperatures at the two ends of the two third conductive thermal resistances connected in series are related to the boundary temperature of the respective basic thermal modeling element according to the third direction.

[0052] The first direction may be the X direction, the second direction may be the Y direction, and the third direction may be the Z direction, which corresponds to the three orthogonal spatial directions. In other embodiments, for example, cylindrical coordinates may be used, which allows for partial use of previously available models.

[0053] According to one embodiment of the present invention, the method further includes performing a model parameter calibration, including calibrating the thermal conductivity and heat capacity of each of the basic thermal modeling elements with at least one of the two first, second, and / or third conductive thermal resistances, the first and / or second error-compensating thermal resistances, before using the thermal model, by comparing estimated temperature values ​​with measured temperature values ​​and / or minimizing an error function.

[0054] Parameter calibration may need to be performed only once. After the parameters are determined or calibrated, the model can be utilized live (in real time) without adjusting the respective model parameters. Temperature values ​​may be measured at different boundaries of each modeled generator component or generator component portion, and may be measured in bulk regions to determine actual hot spot temperatures and average temperatures. Least-squares minimization of the error between the estimated and measured temperatures may be performed, for example, according to Gaussian minimization of the squared error. Other calibration methods may be available or applied.

[0055] According to one embodiment of the present invention, there is provided a method for controlling a permanent magnet synchronous electric generator including a plurality of generator components comprising a rotor, a permanent magnet, and a stator having teeth and windings, the method comprising: performing a permanent magnet synchronous electric generator temperature estimation method according to one of the above-described embodiments; and controlling the permanent magnet synchronous electric generator based on the estimated plurality of temperature values.

[0056] Accurate temperature estimation can improve generator control. Thus, in particular, overheating can be avoided by downregulating one or more reference values ​​when the determined hot spot temperature and / or average temperature exceed one or more temperature thresholds. This can reduce damage or wear to the generator.

[0057] According to one embodiment of the present invention, the electrical and / or mechanical operating parameters of the generator include at least one of the following: current, rotor speed, coolant temperature, and ambient temperature.

[0058] According to other embodiments, coolant temperature may not be utilized as an operating parameter, and other or fewer operating parameters may be utilized.

[0059] It is to be understood that the features disclosed, described, illustrated or provided for the method for temperature estimation of a permanent magnet synchronous electric generator, individually or in any combination, may also be applied individually or in any combination to the apparatus for temperature estimation of a generator according to embodiments of the present invention, and vice versa.

[0060] According to one embodiment of the present invention, an apparatus for temperature estimation of a permanent magnet synchronous electric generator including a plurality of generator components comprising a rotor, a permanent magnet, and a stator having teeth and windings, the apparatus comprising: an input port adapted to receive values ​​of electrical and / or mechanical operating parameters of the generator; and an implementation of a thermal model of the generator comprising a plurality of basic thermal modeling elements partially connected to each other in a network for modeling heat transfer, each generator component being modeled by one or more of the plurality of basic thermal modeling elements, at least one basic thermal modeling element including, for each of a plurality of directions, two conductive thermal resistances modeling the thermal resistance between respective portions of the generator component in opposite directions towards their boundaries; An apparatus is provided, comprising: a star point connected to a plurality of (e.g., three) midpoints between each two conductive thermal resistances; a heat supply and / or absorption system modeling a heat source and / or heat sink; and first and second error-compensating thermal resistances connected in series between the star point and the heat supply and / or absorption system, the apparatus comprising: a processor having access to an implementation of a thermal model, the processor configured to: estimate a plurality of values ​​of temperatures of a plurality of basic modeling elements by feeding a plurality of values ​​of operating parameters to the thermal model; and model heat transfer between and within a plurality of generator components or parts according to the connectivity and thermal resistances within the network and within the basic thermal modeling elements.

[0061] The apparatus may be configured to perform a method for temperature estimation of a permanent magnet synchronous electric generator, which may be implemented in software and / or hardware.

[0062] The processor may have arithmetic / logical processing capabilities and may have access to software instructions or software programs including instructions for, or configured to, implement or control or execute a method of temperature estimation.

[0063] According to one embodiment of the present invention, there is provided a controller for controlling a permanent magnet synchronous electric generator including a plurality of generator components comprising a rotor, a permanent magnet, and a stator having teeth and windings, the controller comprising an apparatus according to the above-described embodiment and a control unit adapted to control the generator based on estimated temperature values.

[0064] According to one embodiment of the present invention, there is provided a wind turbine comprising a permanent magnet synchronous electric generator including a plurality of generator components comprising a rotor, a permanent magnet, and a stator having teeth and windings, a hub having a plurality of rotor blades, the hub being coupled to the rotor, and a controller according to the above-described embodiment.

[0065] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings, in which: FIG. [Brief explanation of the drawings]

[0066] [Figure 1] 1 illustrates schematically a wind turbine according to an embodiment of the present invention; [Figure 2] 1 shows a schematic and partial view of a thermal model used according to an embodiment of the present invention; [Figure 3] 1 illustrates schematically the basic thermal modeling elements used according to an embodiment of the present invention. [Figure 4] 1 shows a schematic cross-sectional view of a portion of a generator with network nodes of basic thermal modeling elements for modeling the generator. [Figure 5] 5 shows a schematic longitudinal cross-sectional view of the thermal node configuration of the thermal model of FIG. 4 for modeling a permanent magnet generator. [Figure 6]1 illustrates schematically a portion of a thermal model implemented as a network of basic thermal modeling elements used in accordance with an embodiment of the present invention; [Figure 7] 1 illustrates schematically a wind turbine according to an embodiment of the present invention; [Figure 8] 1 shows a schematic diagram of a method scheme for setting up a thermal model and / or calibrating model parameters. [Figure 9] 1 shows a schematic diagram of a method scheme for setting up a thermal model and / or calibrating model parameters.

[0067] MODE FOR CARRYING OUT THE INVENTION The drawings are shown in schematic form. It should be noted that in different figures, elements that are similar or identical in structure and / or function are designated with the same reference numerals or reference numerals that differ only in first digit. The description of an element not described in one embodiment can be taken from the description of this element for another embodiment.

[0068] The wind turbine 100, shown schematically in FIG. 1, comprises a permanent magnet synchronous electric generator 101 that includes multiple generator components, including a rotor 102 with a rotor housing 103 and permanent magnets 104 (on a base plate 104a), and a stator 105 with teeth 106 (on a support or frame 106a) and windings 107. The generator 101 is an external rotor type generator. The rotor 102 is mechanically connected to a hub 108 to which multiple rotor blades 109 are connected. The wind turbine 100 may be a direct-drive wind turbine. Thus, the wind turbine 100 may be a gearless wind turbine, in which the generator 101 is directly connected to the hub 108 without an intermediate gearbox.

[0069] The wind turbine 100 further comprises a controller 110 for controlling the generator 101 according to an embodiment of the present invention. The controller 110 comprises a device 111 for temperature estimation of the generator 101 according to an embodiment of the present invention. Furthermore, the controller 110 comprises a control portion 112 (e.g., including a processor) adapted to control the generator 101 based on an estimated temperature value 113 estimated by the device 111.

[0070] The apparatus 111 is described in more detail below with reference to Figure 7. Briefly, the apparatus 111 receives values ​​115 of a plurality of electrical and / or mechanical operating parameters of the generator 101 at an input port 114. The apparatus 111 further includes an implementation of a thermal model of the generator 101, whereby the apparatus 111 estimates a plurality of values ​​113 of temperatures of different generator components based on the plurality of values ​​115 of the operating parameters.

[0071] The estimated temperature value 113 is then utilized by the control portion 112 to derive a control signal 116 that is subsequently utilized to control the generator 101, for example, by providing the control signal 116 to a converter connected to the generator 101.

[0072] Figure 2 schematically illustrates a thermal model 120 such as may be utilized by the apparatus 111 shown in Figure 1. The Z direction therefore corresponds to the axial direction 117 of the generator 101. The thermal model 120 illustrated in Figure 2 includes model portions or segments 120a, 120b, ..., each modeling a particular axial region of the generator 101. Each model portion 120a, b, ... comprises multiple basic thermal modeling elements 121a, 121b, 121c, 121d, 121e, which model different generator components or portions of different generator components.

[0073] For example, basic thermal modeling element 121a models a particular axial region of rotor 102, element 121b models the axial region of permanent magnets 104, element 121c models the axial region of stator windings 107, element 121d models the axial region of stator teeth 106, and element 121e models the axial region of the stator yoke. According to other embodiments, more or fewer basic thermal modeling elements 121 may be provided or implemented. Between the rotor and the stator, the air gap is modeled by specific conductance resistances 122'a, 122'b, 122'c, 122'd that model heat conduction in the Z direction (117) and the radial direction 123.

[0074] An embodiment of the present invention provides a method for real-time temperature estimation in a generator, as shown in Figure 1. According to model 120, both conductive and convective heat transfer are considered.

[0075] Basic thermal modeling elements 121a, ..., 121e are collectively labeled with reference numeral 121. At least one of the basic thermal modeling elements shown in model 120 of Figure 2 is configured as basic thermal modeling element 322 shown in Figure 3. Other basic thermal modeling elements may be configured as one of basic thermal modeling elements 322' or 322'' also shown in Figure 3, or as element 322.

[0076] 3 comprises, for each of a plurality of directions X, Y, Z, two conductive thermal resistances (R_X,1, R_X,2 for the X direction; R_Y,1, R_Y,2 for the Y direction; R_Z,1, R_Z,2 for the Z direction) that model the thermal resistance between respective portions of the generator components towards boundaries in opposite directions (i.e., X direction, Y direction, and Z direction). The boundary temperature values ​​are R_X,1, R_X,2 for the X direction; R_Y,1, R_Y,2 for the Y direction; and R_Z,1, R_Z,2 for the Z direction.

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[0077] The basic thermal modeling element 322 further comprises a star point 324 connected to three plurality of midpoints 325x, 325y, 325z between each two conductive thermal resistances R_X,1, R_X,2, .... The basic thermal modeling element 322 further comprises a heat supply and / or absorption system 326 that models a heat source and / or heat sink. Additionally, the basic thermal modeling element 322 comprises first and second error-compensating thermal resistances R_M1, R_M2 connected in series between the star point 324 and the heat supply and / or absorption system 326.

[0078] The device 111 shown in the controller 110 of Figure 1 uses at least one basic thermal modeling element, such as shown as element 322 in Figure 3, in the model 120 shown in Figure 2 to model the generator 101 shown in Figure 1. According to certain embodiments of the invention, each of the basic thermal modeling elements 221a, 221b, 221c, 221d, 221e, as shown for model portion 120a and for other model portions 120b, ..., is implemented according to element 322 shown in Figure 3. In other embodiments, one or more basic thermal modeling elements may be implemented according to elements 322', 322'' shown in Figure 3.

[0079] These basic thermal modeling elements 322, 322', 322" all include respective star points 324, 324', 324", which also include two respective conductive thermal resistances for each of a number of directions. However, the basic thermal modeling elements 322', 322" shown in FIG. 3 can only determine, for example, the hot spot temperature or the average temperature of a generator component, but not both the hot spot temperature and the average temperature.

[0080] The hot spot temperature that can be estimated using the basic thermal modeling element 322 is labeled with the reference symbol θ_MID, and the average temperature is labeled with the reference symbol θ_avg. Element 322′ is sometimes conventionally referred to as an I-type model, and element 322″ is sometimes referred to as a T-type basic element. The conventional I-type and T-type basic thermal elements are designed to estimate the midpoint temperature and the average temperature, respectively. However, as mentioned above, their estimation accuracy cannot be guaranteed. These conventional elements 322′, 322″ are unable to simultaneously estimate the average temperature and the midpoint temperature.

[0081] In the proposed basic thermal model, the conductive thermal resistance

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[0082] For each component, the temperature rise caused by the boundary temperature difference and internal heat generation follows the principle of superposition. On the one hand, the temperature rise of each component caused by the boundary temperature difference can be calculated by the conduction thermal resistance (Equation 1). On the other hand, the temperature rise caused by internal heat generation needs to be calculated based on the multidimensional conduction heat transfer equation (2) under the condition of zero boundary temperature.

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[0083] By using the method of separating variables, the final solution for the temperature distribution is expressed as (3).

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[0084] According to (3), the space midpoint temperature θ_mid and the average temperature θ_avg can be calculated as follows:

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[0085] The temperature deviation from that estimated at the star point to the analytically calculated midpoint / average temperature, i.e., θ_mid / θ_avg, is calculated by (7) and expressed as (8) using two compensation thermal resistances:

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[0086] 4 and 5 show the thermal node configuration of a modeled generator 401. The nodes hold indices that indicate the generator component or portion of the generator component being modeled. For example, index "ambient" refers to the surrounding environment, index "R" refers to the rotor housing, index "M" refers to the permanent magnets, index "AG" refers to the air gap, index "W" refers to the windings, indexes "T" and "Y" refer to the stator yoke or teeth, and index "F" refers to the stator frame.

[0087] The node configurations shown in Figures 4 and 5 can be adapted according to requirements and can be changed as desired by the thermal designer. The node configurations can vary from simple configurations with a few nodes to complex configurations with many more nodes. Each node can be implemented by one of the basic thermal modeling elements 322', 322'', 322 shown in Figure 3.

[0088] FIG. 6 schematically illustrates a portion of a thermal model 620 used in accordance with an embodiment of the present invention. The thermal model 620 can be considered a high-order discrete thermal model for predicting spatial temperature distribution. The topology of each individual element 622 of the model 620 illustrated in FIG. 6 may be implemented as a basic thermal modeling element 322′, 322″, or 322, with at least one of the elements 622 configured as the exemplary thermal modeling element 322 illustrated in FIG. 3. Furthermore, thermal resistances are derived, for example, according to equations (1) and (8). While complex thermal models can be a computationally time-consuming process, a higher resolution (more nodes) of the thermal network can provide more details about the temperature distribution in the main components of the generator.

[0089] The temperature value estimated between the first error compensation resistor R_M1 and the second error compensation resistor R_M2

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[0090] The first and second error compensation resistors R_M1 and R_M2 can be calculated based on the material and / or design and / or geometry of the modeled components, as detailed in Equations (7) and (8). Equation (2) can be considered a heat transfer or energy conservation theorem that can be used in accordance with embodiments of the present invention. Resistors R_x,1 and R_x,2 can be considered as first conductive thermal resistors connected in series in a first direction, i.e., the X-direction. Similar nomenclature can be applied to the Y- and Z-directions.

[0091] Figure 7 shows a schematic of a wind turbine 700 according to one embodiment of the present invention. The wind turbine comprises a permanent magnet synchronous electric generator 701, with a rotor connected to a hub 708 having a number of rotor blades 709 attached thereto. In the embodiment shown, the generator 701 is connected to an inverter or converter 730, which is controlled by a controller 710.

[0092] The controller 710 comprises a device 711 for temperature estimation of the generator 701. At an input port 714, the device 701 receives values ​​715a, 715b, 715c of several operating parameters of the generator, in this case the rotational speed Ω_R, the coolant and the ambient temperature 715b. The device 711 further receives the current 715c in the d and q reference frames as an electrical input parameter.

[0093] The device 711 comprises a thermal model, such as the thermal model shown in Figure 2 or 6, for estimating values ​​713 of the temperatures of a number of generator components. The generator currents i a, ib, ic are measured and transformed into a rotated dq frame using a transformation module 731.

[0094] The controller 710 further comprises a PI control 732, 733 that receives the rotational speed or current error values, respectively, to provide a current and / or voltage reference 734 in the dq frame, which is transformed to the alpha-beta frame by a transformation model 735. The voltage reference is then fed to a space vector pulse width modulation module 736, which then calculates gate signals for a plurality of controllable switches included in the inverter or converter 730 to control the generator 701. The rotational speed Ω_R is measured by an encoder 737.

[0095] The controller 710 may or may not also include an offline thermal property calibration module 738 that may be utilized for parameter calibration of the model 120 utilized by the device 711 (providing parameters 738 to the device 711). As can be seen from FIG. 7, a real-time temperature estimation system is integrated into the controller 710 of the generator 701. The dq-axis currents, rotor speed, and coolant and ambient temperatures are measured and these quantities are input into the real-time temperature estimation system or device 711. The real-time temperature estimation system consists of a high-fidelity thermal model for calculation of major mechanical losses and offline thermal calibration.

[0096] Figure 8 schematically illustrates a complete temperature estimation flowchart 840. First, a parametric thermal model, such as that shown in Figure 2, is established according to the geometric parameters, and the thermal properties, including thermal conductivity, heat capacity, and contact thermal resistance, are calibrated. More specifically, by using optimization algorithms, such as particle swarm optimization, genetic algorithms, and sequential quadratic programming, the thermal parameters are identified by minimizing the least-squares error between the predicted and measured temperatures in Equation (9). The measured temperature information can be obtained from prototype testing. The implementation of the thermal property calibration is shown in Figure 7. It is worth noting that the calibration process only needs to be performed once based on a prototype PMSG and can then be used for different PMSGs manufactured by the same supplier.

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[0097] Next, the mechanical losses are measured / calculated, including iron losses, PM losses, copper losses, and mechanical losses, which can be modeled as a function of rotor speed, dq-axis currents, and DC bus voltage.

[0098] Third, the thermal resistance can be calculated by equations (1)-(4) based on the geometric parameters and calibrated thermal properties, so that the complete thermal model can be described by the state-space equations.

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[0099] Fourth, for real-time implementation, the state-space equations in (10) and (11) are solved by numerical techniques, e.g., the fourth-order Runge-Kutta method, which can be expressed as follows:

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[0100] Finally, the temperature vector

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[0101] 9 shows in more detail the calibration method 950. Based on the measured and estimated temperatures, the model parameters may be adjusted.

[0102] Embodiments of the invention may provide one or more of the following advantages. The estimated temperatures in the developed system include both average and hot spot temperatures with high estimation accuracy, which is more significant than the average temperature calculated based on estimated stator winding resistance and PM flux linkage. The developed temperature estimation system is non-invasive, i.e., no injection of additional perturbation signals is required. Therefore, the temperature estimation does not have a detrimental effect on the reliability and stability of the system. The estimation accuracy is robust to measurement noise and is achievable over the entire torque-speed range. However, some identification methods cannot be applied in the low speed range due to the low signal-to-noise ratio.

[0103] Embodiments of the present invention may provide one or more of the following technical features. The proposed method can be used for online hotspot / average temperature monitoring of PMSGs, minimizing or even eliminating the number of installed thermal sensors. This reduces the cost of measurement devices and maintenance, while the reduced utilization of thermal sensors also improves system stability. In the proposed temperature estimation method, the node configuration can be adjusted according to requirements, and therefore the spatial temperature distribution is predictable. Therefore, the effects of non-uniform loss generation, such as PM loss and AC copper loss, can be taken into account, which can have a significant impact on the maximum temperature rise of the windings and PM. The thermal properties of the main components can be calibrated in advance, therefore the developed temperature estimation system can be applied to DD PMSGs with different sizes without any additional parameter calibration. The proposed method can be implemented inside the embedded turbine control system to effectively control the generator winding temperature and prevent any thermal overload, which can be considered for all SGRE direct drive generators. The proposed method has a significant impact on extending the turbine life (e.g., thermal insulation system) and preventing any thermal overload conditions, thereby improving operational reliability. · The calibration process is required only once for a series of DD PMSGs made by the same supplier, and therefore the proposed scalable temperature estimation system is time-efficient.

[0104] It should be noted that the term "comprising" does not exclude other elements or steps, and "a" or "an" do not exclude a plurality. Also, elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

1. 1. A method of temperature estimation for an electric generator (101) including a plurality of generator components, including a rotor (102) and a stator (105) having teeth (106) and windings (107), said method comprising: receiving values ​​(115) of electrical and / or mechanical operating parameters of the generator (101); - using a thermal model (120) of said generator (101) comprising a plurality of elementary thermal modeling elements (121a, b, c, d, e; 322) partially connected to each other in a network for modeling heat transfer; Including, each generator component is modeled by one or more of said plurality of basic thermal modeling elements (322, 322', 322''); The at least one basic thermal modeling element (322) comprises: two conductive thermal resistances (R_x,1; R_x,2; R_y,1; R_y,2; R_z,1; R_z,2) for each of a plurality of directions that model the thermal resistance between respective portions of the generator component in opposite directions towards its boundary; Star points (324) connected to a plurality of midpoints (325x, 325y, 325z) between each pair of conductive thermal resistances; a heat supply and / or absorption system (326) that models the heat source and / or heat sink; first and second error-compensating thermal resistances (R_m1, R_m2) connected in series between the star point (324) and the heat supply and / or absorption system (326); Equipped with The method comprises: - estimating a plurality of values ​​(113) of temperatures of the plurality of basic modeling elements by feeding the plurality of values ​​(115) of the operating parameters to the thermal model (120), in particular including or implemented in software, modeling heat transfer between and within the plurality of generator components or parts according to connectivity and thermal resistances within the network and within the basic thermal modeling elements; Including, method.

2. 2. The method according to claim 1, wherein the estimated temperature value between the first error compensation resistor (R_m1) and the second error compensation resistor (R_m2) is considered as a hot spot temperature (theta_mid), in particular a maximum temperature, of the respective component or part.

3. 3. The method according to claim 1 or 2, wherein the temperature value determined between the second error compensation resistor (R_m2) and the heat supply and / or absorption system (326) is considered as the average temperature (theta_avg) of the respective component or component part.

4. 4. The method of claim 1, wherein both the maximum temperature and the average temperature of each component or component part are estimated by the method.

5. 5. The method according to claim 1, wherein the first and / or the second error compensation resistance (R_m1, R_m2) is calculated based on material and / or dimensions and / or volume and / or equivalent resistance accounting for parallel conduction and / or eigenvalues ​​in multiple directions of the component or component part, in particular as a sum of multiple products of sine functions over multiple (nodal) indices for three directions.

6. 6. The method of claim 1, wherein each generator component in each of a plurality of spatial regions is modeled by one or more of the plurality of basic thermal modeling elements (322, 322', 322''), each associated with boundary temperature values ​​and bulk temperature values ​​in a plurality of directions, and the thermal connections of the plurality of generator components or component portions are modeled by heat transfer between boundaries of respective adjacent or neighboring basic thermal network elements.

7. estimating the plurality of temperature values ​​(113) by applying the heat transfer theorem or the energy conservation theorem to the model; and / or estimating the plurality of values ​​of temperature (113) is performed sensorlessly without measuring any temperature of the generator except for the cooling fluid temperature; and / or estimating the plurality of temperature values ​​(113) is performed in real time during operation of the generator; and / or estimating generator losses based on said estimated temperature values ​​(113); and / or estimating the wear and / or life of a component or component part based on said estimated temperature value; and / or diagnosing a fault in a component or component portion based on said estimated temperature value; 7. The method of claim 1, comprising:

8. For each basic thermal modeling element: two first conductive thermal resistances (R_x,1; R_x,2) connected in series in a first direction (x); two second conductive thermal resistances (R_y,1; R_y,2) connected in series in a second direction (y); two third conductive thermal resistors (R_z,1; R_z,2) connected in series in a third direction (z); a first point (325x) between the two first conductive thermal resistors connected in series is connected to the star point (324); a second point (325y) between the two second conductive thermal resistors connected in series is connected to the star point (324); a third point (325z) between the two third conductive thermal resistors connected in series is connected to the star point (324); temperatures at two ends of the two first conductive thermal resistances connected in series are related to the boundary temperatures of the respective basic thermal modeling elements according to the first direction; temperatures at two ends of the two second conductive thermal resistances connected in series are related to the boundary temperatures of the respective basic thermal modeling elements according to the second direction; the temperatures at the two ends of the two third conductive thermal resistances connected in series are related to the boundary temperatures of the respective basic thermal modeling elements according to the third direction.

8. The method according to any one of claims 1 to 7.

9. Before using the thermal model, By comparing the estimated temperature values ​​with the measured temperature values ​​and / or minimizing an error function; the two first, second, and / or third conductive thermal resistances (R_x,1; R_x,2; R_y,1; R_y,2; R_z,1; R_z,2), the first and / or second error compensation thermal resistors (R_m1, R_m2); for each of the basic thermal modeling elements.

9. The method of claim 1, further comprising:

10. 1. A method for controlling an electric generator including a plurality of generator components comprising a rotor and a stator having teeth and windings, the method comprising: Implementing a method for temperature estimation of an electric generator (101) according to any one of claims 1 to 9; controlling the electric generator (101) based on the estimated values ​​(113) of temperature; Including, method.

11. The electrical and / or mechanical operating parameters (115) of the generator are: current, rotor speed, Coolant temperature, Ambient temperature The method of claim 10, comprising at least one of:

12. 1. An apparatus (111, 711) for temperature estimation of an electric generator (101, 701) including a plurality of generator components, the generator components comprising a rotor (102) and a stator (105) having teeth (106) and windings (107), the apparatus comprising: an input port (114) adapted to receive values ​​(115) of electrical and / or mechanical operating parameters of the generator; A solution for implementing a thermal model (120), in particular including software or implemented in software, for said generator (101), comprising a plurality of elementary thermal modeling elements (221 a, b, c, d, e; 322) partially connected to one another in a network for modeling heat transfer, each generator component is modeled by one or more of the plurality of fundamental thermal modeling elements; Implementation solutions and Equipped with The at least one basic thermal modeling element (322) comprises: two conductive thermal resistances (R_x,1; R_x,2; R_y,1; R_y,2; R_z,1; R_z,2) for each of a plurality of directions that model the thermal resistance between respective portions of the generator component in opposite directions towards its boundary; Star points (324) connected to a plurality of midpoints (325x, 325y, 325z) between each pair of conductive thermal resistances; a heat supply and / or absorption system (326) that models the heat source and / or heat sink; first and second error-compensating thermal resistances (R_m1, R_m2) connected in series between the star point (324) and the heat supply and / or absorption system (326); Equipped with The device comprises: a processor having access to the implementation of a thermal model (120) and configured to estimate a plurality of values ​​(113) of temperatures of the plurality of basic modeling elements (121 a, b, c, d, e; 322) by feeding the plurality of values ​​(115) of the operating parameters to the thermal model, and to model heat transfer between and within the plurality of generator components or parts according to connectivity and thermal resistances within the network and within the basic thermal modeling elements. Equipped with Device.

13. A controller (110) for controlling an electric generator including a plurality of generator components comprising a rotor and a stator having teeth and windings, said controller comprising: An apparatus (111) according to claim 12, a control unit (112) adapted to control the generator based on the estimated temperature value; A controller comprising:

14. A wind turbine (100), comprising: an electric generator (101) including a plurality of generator components comprising at least a rotor (102) and a stator having teeth and windings; a hub (108) having a plurality of rotor blades (109), said hub being coupled to said rotor (102); A controller (110) according to claim 13; Equipped with The generator may in particular a permanent magnet synchronous electric generator (101) including a rotor (102) having permanent magnets; Electrically excited asynchronous machine, or doubly fed induction machine [0033] Wind turbines.

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