Motor temperature simulation method and system

Abstract

The present invention relates to a motor temperature simulation method and system, the simulation method comprising: constructing an electrical model of a motor; constructing an endogenous heat model of a motor; equivalent the motor housing, stator yoke, stator teeth and rotor to a round-wall cylinder, equivalent the motor winding and shaft to a cylinder to construct a thermal network model of the motor; selecting the temperature nodes of the motor in the thermal network model, and constructing the transient thermal balance equation of the motor based on the temperature nodes; connecting the electrical model, the endogenous heat model and the thermal network model in sequence to obtain a multi-field coupling model of the motor; simulating the temperature change during the operation of the motor based on the multi-field coupling model, and using a gradient descent algorithm to update the motor parameters in the multi-field coupling model, so that the difference between the simulated temperature obtained by simulation and the actual temperature of the motor is less than a preset threshold. The multi-field coupling model established by the present invention can adjust the motor parameters during the simulation process to increase the accuracy of the simulation.

Description

Technical Field

[0001] The present invention relates to the technical field of motor temperature simulation, and in particular to a motor temperature simulation method and system. Background Art

[0002] Permanent magnet synchronous motors have been widely used in various fields due to their good performance reliability, low probability of failure, high operating efficiency and small size. As an electrical component, the internal temperature of the motor has an important influence on the motor performance and service life, so it is necessary to study the mathematical model of the motor and the solution of the internal temperature.

[0003] At present, the temperature solution of the motor is mainly based on finite element analysis, which takes a long time to solve and cannot change its internal parameters during simulation. It is equivalent to a steady-state motor thermal simulation and cannot solve its transient temperature as the internal parameters change. When there is an error between the simulation results and the sensor results, it is impossible to adjust the internal parameters in real time. Therefore, the simulation based on commercial software always differs from the actual sensor results. Placing sensors to obtain temperature at the same time is not only costly, but also placing temperature measurement nodes inside will damage the structure of the motor and reduce the reliability of the motor operation. How to provide a motor temperature simulation method that can adjust the internal parameters of the motor in real time to improve the accuracy of motor temperature simulation has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of this, the present invention provides a motor temperature simulation method and system, so as to provide a motor temperature simulation method capable of adjusting the internal parameters of the motor in real time to improve the motor temperature simulation accuracy.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A motor temperature simulation method, the simulation method comprising the following steps:

[0007] Build an electrical model of the motor;

[0008] Construct an endogenous heat model of the motor;

[0009] The motor housing, stator yoke, stator teeth and rotor are equivalent to a circular wall cylinder, and the motor winding and shaft are equivalent to a cylinder to construct a thermal network model of the motor;

[0010] Selecting temperature nodes of the motor in the thermal network model, and constructing a transient thermal balance equation of the motor based on the temperature nodes; the transient thermal balance equation is used for calculation of the thermal network model;

[0011] The electrical model, the endogenous heat model and the thermal network model are sequentially connected to obtain a multi-field coupling model of the motor;

[0012] The temperature change during the operation of the motor is simulated based on the multi-field coupling model, and the motor parameters in the multi-field coupling model are updated using a gradient descent algorithm so that the difference between the simulated temperature and the actual temperature of the motor is less than a preset threshold.

[0013] Optionally, the endogenous heat model is:

[0014]

[0015] Among them, G iron is the heat source of the stator yoke, G Fei Generates heat for the stator yoke, G Fei =K ai p Fei m Fei , m Fei is the weight of the stator yoke; K ai is the empirical coefficient for the increase in stator yoke loss; p Fei is the loss of silicon steel sheet per unit mass of the stator yoke, p 10 / 50,i B is the loss of the silicon steel sheet per unit mass of the stator yoke when B = 1T, f0 = 50Hz, iron Indicates the maximum magnetic flux density in the stator yoke, T iron represents the stator yoke temperature, B represents the magnetic flux density, f represents the magnetic field frequency, and f0 represents the rated frequency of the magnetic field;

[0016] G teeth is the heat source of the stator teeth, G Fet Generates heat for the stator teeth, G Fet =K at p Fet m Fet , m Fet is the weight of the stator teeth, K at is the empirical coefficient for the increase in stator tooth loss, p Fet is the stator tooth loss ratio, p 10 / 50,t It represents the loss of silicon steel sheet per unit mass of stator teeth when B = 1T, f0 = 50Hz, B teeth Indicates the maximum magnetic flux density in the stator yoke, T teeth Indicates the stator tooth temperature;

[0017] G rotor is the rotor heat source, P R The permanent magnet generates heat, P R =∫J 2 / σdV, J is the eddy current density of the permanent magnet; σ is the electrical conductivity of the permanent magnet, V is the volume of the permanent magnet, P hGenerate heat for the rotor, P h =k1C f πρω m 3 r 4 l, k1 is the roughness coefficient of the rotor surface; r is the rotor radius; l is the axial length of the rotor; C f is the air friction coefficient; ρ is the air density; ω m is the rotor mechanical angular velocity;

[0018] G winding is the winding heat source, i a ,i b ,i c is the three-phase current of the motor, R winding (T winding ) is the temperature T winding Winding resistance, R winding (T winding )=R 0,winding (1+α cu (T winding -T 15 )), α Cu is the temperature coefficient of conductor resistance; R winding (T winding ) is the temperature T endwinding End winding resistance, T winding is the winding temperature, R 0,winding is the winding resistance at 15°C, T 15 15℃;

[0019] G endwinding is the end winding heat source, R endwinding (T endwinding ) is the temperature T endwinding The end winding resistance, R endwinding (T endwinding )=R 0,endwinding (1+α cu (T endwinding -T 15 )), R 0,endwinding Indicates the end winding resistance at a temperature of 15°C, T endwinding is the end winding resistance temperature.

[0020] Optionally, the heat capacity calculation formula of the round-wall cylinder and the cylinder in the thermal network model is:

[0021] C=ρ·c p ·V;

[0022] Where C is the heat capacity, ρ is the material density of the round-walled cylinder or cylinder, and c pis the specific heat of the round-walled cylinder or cylinder material, V is the volume of the round-walled cylinder or cylinder;

[0023] The thermal resistance calculation formula of the round wall cylinder is:

[0024]

[0025] Among them, R a is the radial thermal resistance of the round-walled cylinder, R 1r is the axial thermal resistance of the inner wall of the circular cylinder, R 2r is the axial thermal resistance of the outer wall of the round-wall cylinder, r1 and r2 are the inner radius and outer radius of the round-wall cylinder respectively, L is the length of the round-wall cylinder, and k is the thermal conductivity of the round-wall cylinder material;

[0026] The thermal resistance of a cylinder is calculated as:

[0027]

[0028]

[0029] Among them, R r ' represents the axial thermal resistance of the cylinder, k' represents the thermal conductivity of the cylinder material, L' represents the length of the cylinder, r' represents the radius of the cylinder, R' a Represents the radial thermal resistance of the cylinder.

[0030] Optionally, the transient heat balance equation is:

[0031] in, represents the heat capacity matrix, C1, C n and C N denote the heat capacities of the 1st, nth and Nth temperature nodes respectively;

[0032] is the thermal conductivity matrix, Y1,Y n and Y N They represent the thermal conductance of the 1st, nth and Nth temperature nodes respectively. The thermal conductance of each temperature node is obtained by adding the reciprocal of the thermal resistance of the connecting branches of each temperature node;

[0033] is the temperature node matrix, T1, T n and T N Represent the temperatures of the 1st, nth and Nth temperature nodes respectively;

[0034] is the endogenous heat matrix, G1, G n and GN They represent the internal heat of the 1st, nth and Nth temperature nodes respectively. When the nth temperature node is located at the stator yoke, G n =G iron , when the nth temperature node is located at the stator tooth G n =G teeth , when the nth temperature node is located at the rotor G n =G rotor , when the nth temperature node is located in the winding G n =G winding , when the nth temperature node is located at the end winding G n =G endwinding .

[0035] A motor temperature simulation system, the simulation system comprising:

[0036] Electrical model building module, used to build the electrical model of the motor;

[0037] An endogenous heat model building module is used to build an endogenous heat model of the motor;

[0038] A thermal network model building module is used to construct a thermal network model of the motor by equating the motor housing, stator yoke, stator teeth and rotor to a circular wall cylinder, and the motor winding and shaft to a cylinder;

[0039] A transient heat balance equation construction module, used for selecting temperature nodes of the motor in the thermal network model, and constructing a transient heat balance equation of the motor based on the temperature nodes; the transient heat balance equation is used for calculation of the thermal network model;

[0040] A multi-field coupling model building module, used to sequentially connect the electrical model, the endogenous heat model and the transient heat balance equation to obtain a multi-field coupling model of the motor;

[0041] The simulation module is used to simulate the temperature change during the operation of the motor based on the multi-field coupling model, and use the gradient descent algorithm to update the motor parameters in the multi-field coupling model so that the difference between the simulated temperature and the actual temperature of the motor is less than a preset threshold.

[0042] Optionally, the endogenous heat model is:

[0043]

[0044] Among them, G iron is the heat source of the stator yoke, G Fei Generates heat for the stator yoke, G Fei =K ai p Fei m Fei , mFei is the weight of the stator yoke; K ai is the empirical coefficient for the increase in stator yoke loss; p Fei is the loss of silicon steel sheet per unit mass of the stator yoke, p 10 / 50,i B is the loss of the silicon steel sheet per unit mass of the stator yoke when B = 1T, f0 = 50Hz, iron Indicates the maximum magnetic flux density in the stator yoke, T iron represents the stator yoke temperature, B represents the magnetic flux density, f represents the magnetic field frequency, and f0 represents the rated frequency of the magnetic field;

[0045] G teeth is the heat source of the stator teeth, G Fet Generates heat for the stator teeth, G Fet =K at p Fet m Fet , m Fet is the weight of the stator teeth, K at is the empirical coefficient for the increase in stator tooth loss, p Fet is the stator tooth loss ratio, p 10 / 50,t It represents the loss of silicon steel sheet per unit mass of stator teeth when B = 1T, f0 = 50Hz, B teeth Indicates the maximum magnetic flux density in the stator yoke, T teeth Indicates the stator tooth temperature;

[0046] G rotor is the rotor heat source, P R The permanent magnet generates heat, P R =∫J 2 / σdV, J is the eddy current density of the permanent magnet; σ is the electrical conductivity of the permanent magnet, V is the volume of the permanent magnet, P h Generate heat for the rotor, P h =k1C f πρω m 3 r 4 l, k1 is the roughness coefficient of the rotor surface; r is the rotor radius; l is the axial length of the rotor; C f is the air friction coefficient; ρ is the air density; ω m is the rotor mechanical angular velocity;

[0047] G winding is the winding heat source, i a ,i b ,i c is the three-phase current of the motor, R winding (T winding ) is the temperature T winding Winding resistance, Rwinding (T winding )=R 0,winding (1+α cu (T winding -T 15 )), α Cu is the temperature coefficient of conductor resistance; R winding (T winding ) is the temperature T endwinding End winding resistance, T winding is the winding temperature, R 0,winding is the winding resistance at 15°C, T 15 15℃;

[0048] G endwinding is the end winding heat source, R endwinding (T endwinding ) is the temperature T endwinding The end winding resistance, R endwinding (T endwinding )=R 0,endwinding (1+α cu (T endwinding -T 15 )), R 0,endwinding Indicates the end winding resistance at a temperature of 15°C, T endwinding is the end winding resistance temperature.

[0049] Optionally, the heat capacity calculation formula of the round-wall cylinder and the cylinder in the thermal network model is:

[0050] C=ρ·c p ·V;

[0051] Where C is the heat capacity, ρ is the material density of the round-walled cylinder or cylinder, and c p is the specific heat of the round-walled cylinder or cylinder material, V is the volume of the round-walled cylinder or cylinder;

[0052] The thermal resistance calculation formula of the round wall cylinder is:

[0053]

[0054] Among them, R a is the radial thermal resistance of the round-walled cylinder, R 1r is the axial thermal resistance of the inner wall of the circular cylinder, R 2r is the axial thermal resistance of the outer wall of the round-wall cylinder, r1 and r2 are the inner radius and outer radius of the round-wall cylinder respectively, L is the length of the round-wall cylinder, and k is the thermal conductivity of the round-wall cylinder material;

[0055] The thermal resistance of a cylinder is calculated as:

[0056]

[0057]

[0058] Among them, R r ' represents the axial thermal resistance of the cylinder, k' represents the thermal conductivity of the cylinder material, L' represents the length of the cylinder, r' represents the radius of the cylinder, R' a Represents the radial thermal resistance of the cylinder.

[0059] Optionally, the transient heat balance equation is:

[0060] in, represents the heat capacity matrix, C1, C n and C N denote the heat capacities of the 1st, nth and Nth temperature nodes respectively;

[0061] is the thermal conductivity matrix, Y1,Y n and Y N They represent the thermal conductance of the 1st, nth and Nth temperature nodes respectively. The thermal conductance of each temperature node is obtained by adding the reciprocal of the thermal resistance of the connecting branches of each temperature node;

[0062] is the temperature node matrix, T1, T n and T N Represent the temperatures of the 1st, nth and Nth temperature nodes respectively;

[0063] is the endogenous heat matrix, G1, G n and G N They represent the internal heat of the 1st, nth and Nth temperature nodes respectively. When the nth temperature node is located at the stator yoke, G n =G iron , when the nth temperature node is located at the stator tooth G n =G teeth , when the nth temperature node is located at the rotor G n =G rotor , when the nth temperature node is located in the winding G n =G winding , when the nth temperature node is located at the end winding G n =G endwinding .

[0064] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0065] The present invention discloses a motor temperature simulation method, the simulation method comprising the following steps: constructing an electrical model of a motor; constructing an endogenous heat model of a motor; equivalent the motor housing, stator yoke, stator teeth and rotor to a round wall cylinder, equivalent the motor winding and shaft to a cylinder to construct a thermal network model of the motor; selecting the temperature nodes of the motor in the thermal network model, and constructing the transient thermal balance equation of the motor based on the temperature nodes; the transient thermal balance equation is used for the calculation of the thermal network model; connecting the electrical model, the endogenous heat model and the transient thermal balance equation in sequence to obtain a multi-field coupling model of the motor; simulating the temperature change during the operation of the motor based on the multi-field coupling model, and using a gradient descent algorithm to update the motor parameters in the multi-field coupling model, so that the difference between the simulated temperature obtained by simulation and the actual temperature of the motor is less than a preset threshold. The multi-field coupling model established by the present invention can adjust the motor parameters during the simulation process to increase the simulation accuracy, and the present invention provides a motor temperature simulation method that can adjust the internal parameters of the motor in real time to improve the simulation accuracy of the motor temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0067] Figure 1 A flow chart of a motor temperature simulation method provided by the present invention;

[0068] Figure 2 A block diagram of multi-field coupling of a motor provided by the present invention;

[0069] Figure 3 A structural diagram of a permanent magnet synchronous motor provided by the present invention;

[0070] Figure 4 A simplified schematic diagram of the Mellor thermal network model provided by the present invention;

[0071] Figure 5 A schematic diagram of a motor thermal network model provided by the present invention;

[0072] Figure 6 A schematic diagram of a motor multi-field coupling model provided by the present invention;

[0073] Figure 7 A temperature variation curve diagram of the motor multi-field coupling model provided by the present invention;

[0074] Figure 8A comparison diagram of the motor model without correction algorithm provided by the present invention and the input data; Figure 8 (a) is a comparison diagram of the winding temperature between the motor model without correction algorithm and the input. Figure 8 (b) is a comparison diagram of the end winding temperature between the motor model without correction algorithm and the input. Figure 8 (c) is a comparison diagram of the stator yoke temperature between the motor model without correction algorithm and the input. Figure 8 (d) is a comparison diagram of the stator tooth temperature between the motor model without correction algorithm and the input;

[0075] Fig. 9 A comparison diagram between the magnetic field and winding correction model output provided by the present invention and the actual data; Fig. 9 (a) is a comparison diagram of the magnetic field, winding correction model output and actual winding temperature. Fig. 9 (b) is a comparison diagram of the magnetic field, winding correction model output and the actual end winding temperature. Fig. 9 (c) is a comparison diagram of the magnetic field and winding correction model output and the actual stator yoke temperature. Fig. 9 (d) is a comparison diagram of the magnetic field and winding correction model output and the actual stator tooth temperature;

[0076] Fig.10 A schematic diagram of the output results of selected parameter correction in the magnetic field and winding correction provided by the present invention; Fig.10 (a) is a schematic diagram of the output result of winding resistance correction. Fig.10 (b) is a schematic diagram of the output results of the end winding resistance correction. Fig.10 (c) is a schematic diagram of the output results of the stator yoke magnetic flux density correction. Fig.10 (d) is a schematic diagram of the output results of the stator tooth magnetic flux density correction. DETAILED DESCRIPTION

[0077] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0078] The object of the present invention is to provide a motor temperature simulation method and system, so as to provide a motor temperature simulation method capable of adjusting the internal parameters of the motor in real time to improve the motor temperature simulation accuracy.

[0079] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0080] The present invention establishes a pure mathematical model about the motor temperature, which can solve the heating condition of the motor and all the internal technical conditions, so as to improve the control strategy and prevent the abnormal temperature of the key nodes inside the motor. At the same time, by adjusting the internal parameters, the simulation result output can match the sensor result, so that the established motor model can truly reflect the physical motor state. The present invention establishes the electrical model and thermal network model of the motor, and calculates the loss model of the motor as a link between the electrical model and the thermal model. The motor model thus established (such as Figure 2 As shown in the figure, the internal transient temperature can be solved and the overall technical status can be known. Based on the gradient descent algorithm, the real-time change of internal parameters can be realized, so that the model output follows the sensor results.

[0081] like Figure 1 As shown, the present invention provides a motor temperature simulation method, the simulation method comprising the following steps:

[0082] Step 101, constructing an electrical model of the motor.

[0083] For the overall mathematical model of the motor, the input is a three-phase AC voltage u with a phase difference of 120° a ,u b ,u c , which is converted into dq axis voltage u through Clarke and Park transformation d ,u q As the input of the motor electrical model, the output dq axis current i d ,i q After inverse Park and inverse Clarke transformation, it is converted into three-phase current i a ,i b ,i c In the two-phase rotating coordinate system, the stator voltage equation is:

[0084]

[0085] In the formula, u d ,u q is the dq axis voltage, R is the motor armature resistance, i d ,i q is the dq axis current, Ψ d ,Ψ q is the dq axis flux, ω is the motor electrical angular velocity, and t is time.

[0086] Stator flux equation:

[0087]

[0088] In the formula, Ψ f is the magnetic field of the rotor permanent magnet, L d ,L qis the dq axis inductance.

[0089] Electromagnetic torque equation:

[0090]

[0091] Where, T e is the electromagnetic torque of the motor, n p is the pole pair number.

[0092] Motor motion equation:

[0093]

[0094] In the formula, J e B is the moment of inertia of the entire load system converted to the shaft end. e is the damping coefficient, T L is the load torque.

[0095] Step 102: construct an endogenous heat model of the motor.

[0096] For the heat generation module inside the motor, the main heat sources of the motor are divided into stator, winding and rotor according to the heat generation location. The heat generation of other parts is smaller than that of these three parts, so they are ignored.

[0097] (1) Heat generation in the stator yoke

[0098] The heat generated in the stator yoke is caused by the basic iron loss of the core. The iron loss can be divided into hysteresis loss and eddy current loss due to different causes. However, both can be calculated uniformly by the empirical formula:

[0099] G Fei =K ai p Fei m Fei (5)

[0100] In the formula, m Fei is the weight of the stator yoke; K ai K is the empirical coefficient for the increase in loss caused by the uneven distribution of magnetic flux density due to the imprecise processing of silicon steel sheets and the sinusoidal change of magnetic flux density over time. ai =3.6; p Fei It is the loss of silicon steel sheet per unit mass of stator yoke, that is, specific loss.

[0101] In the specific loss p Fei When calculating, the magnetic flux density value should be selected as the maximum magnetic flux density value B in the stator yoke. iron , while considering the influence of temperature on magnetic flux density, the specific loss can be calculated using the following formula:

[0102]

[0103] In the formula, p 10 / 50 is the loss of the silicon steel sheet per unit mass of the stator yoke when B = 1T, f0 = 50Hz. The specific value can be obtained from the loss curve of the silicon steel sheet of this model. f is the magnetic field frequency, T iron Indicates the stator yoke temperature.

[0104] (2) Heat generation in stator teeth

[0105] The heat generated by the stator teeth is the same as the heat generated by the stator yoke, which is generated by the basic iron loss of the core. The calculation formula is:

[0106] G Fet =K at p Fet m Fet (7)

[0107] In the formula, m Fet is the weight of the stator teeth; K at Consistent with the definition of formula (5), the value here is K at =1.7; p Fet is the stator tooth loss ratio.

[0108] When calculating the stator tooth loss ratio, the magnetic flux density value should be the average value of the stator tooth magnetic flux density B. teeth , considering the influence of temperature on magnetic flux density, the specific loss calculation formula is:

[0109]

[0110] Where, T teeth Indicates the stator tooth temperature

[0111] The relationship between the performance of permanent magnet materials and temperature during motor rotation is:

[0112]

[0113] In the formula, is the remanent magnetic density at T0℃, α B is the reversible temperature coefficient of the material, IL is the loss rate of the magnetic field, T is the motor temperature, and T0 is the reference temperature.

[0114] (3) Winding heat generation

[0115] The heat generated by the winding is caused by the energy loss caused by the current flowing through the resistor. According to Joule's law, its value is equal to the square of the current flowing through the winding multiplied by the winding resistance. This motor is a three-phase symmetrical winding, so the current in each winding needs to be multiplied and superimposed by the respective winding resistance, considering the influence of temperature on the resistance value:

[0116]

[0117] When the winding is energized and heated, the calculation formula for the resistance value changing with temperature is:

[0118] R(T)=R0(1+α cu (TT 15 )) (11)

[0119] Where R0 is the winding resistance at 15°C; α Cu is the temperature coefficient of conductor resistance, for copper T 15 =15℃,α Cu =4×10 -3 ℃ -1 ; T is the current resistance temperature.

[0120] Therefore, formula (1) is modified as follows:

[0121]

[0122] (4) Heat generation by permanent magnets

[0123] For permanent magnet synchronous motors, theoretically, the rotor is driven to rotate by the magnetic field generated by the stator winding, so the rotor speed is consistent with the magnetic field rotation speed, and the permanent magnet will not generate eddy current loss. However, in actual operation, due to the tooth slots and air gap magnetic fields in the stator teeth of the motor, the distribution of the magnetic field cannot be ideal, resulting in eddy current loss in the permanent magnet caused by the harmonic components of the magnetic field. The calculation formula is:

[0124] P R =∫J 2 / σdV (13)

[0125] Where J is the eddy current density of the permanent magnet; σ is the electrical conductivity of the permanent magnet, and V is the volume of the permanent magnet.

[0126] (5) Rotor heat generation

[0127] The heat generated by the rotor is mainly caused by the friction between the rotor surface and the air, and its calculation formula is:

[0128] P h =k1C f πρω m 3 r 4 l (14)

[0129] Where, k1 is the roughness coefficient of the rotor surface; r is the rotor radius; l is the axial length of the rotor; C f is the air friction coefficient; ρ is the air density; ω m =ω / n p is the rotor mechanical angular velocity.

[0130] The heat source of the motor thermal network model can be obtained from the heat generated by the motor, and the relationship is:

[0131]

[0132] In the formula, G iron is the heat source of the stator yoke, that is, the iron loss of the stator yoke; G teeth is the heat source of the stator teeth, that is, the iron loss of the stator teeth; G rotor is the rotor heat source, which is composed of permanent magnet eddy current loss and rotor friction loss; G winding The winding heat source is generated by the heating of the winding; G endwinding The end winding heat source is generated by the heat generated by the end winding. The specific injection position in the thermal network model is Figure 5 Marked in.

[0133] Step 103 , the housing, stator yoke, stator teeth and rotor of the motor are equivalent to a circular wall cylinder, and the winding and shaft of the motor are equivalent to a cylinder to construct a thermal network model of the motor.

[0134] In thermal network modeling, the permanent magnet synchronous motor can be regarded as a device composed of several round-walled cylinders and cylinders, which are the outer shell, stator yoke, stator teeth, winding, rotor, shaft, etc. from the outside to the inside. Figure 3 As shown, Figure 3 In the figure, 1 is a housing, 2 is a stator yoke, 3 is a stator tooth, 4 is a winding, 5 is a rotor, and 6 is a shaft.

[0135] for Figure 3 The housing, stator yoke, stator teeth, and rotor in the figure can be directly regarded as a round-walled cylinder and modeled using a simplified Mellor thermal network, such as Figure 4 shown.

[0136] Figure 4 The simplified Mellor thermal network in the paper is divided into radial and axial directions. It is a two-dimensional thermal network model, where R 1r ,R 2r is the radial thermal resistance, R a is the axial thermal resistance, T r (r1),T r (r2) is the outer and inner wall temperature of the circular cylinder, T a (0),T a (L) is the temperature at both ends of the axial direction of the cylindrical body, which is assumed to be equal, T m is the midpoint temperature of the inner and outer walls, that is, the temperature of the round-walled cylinder in the overall thermal model, G represents the heat source of the round-walled cylinder, and C represents the heat capacity of the round-walled cylinder. The heat capacity calculation formula is:

[0137] c=ρ·c p ·V (16)

[0138] Where ρ is the material density, c p is the specific heat of the material, and V is the volume of the round-walled cylinder.

[0139] The thermal resistance calculation formula is:

[0140]

[0141] Where r1 and r2 are the inner and outer radii of the round-walled cylinder, L is the length of the round-walled cylinder, and k is the thermal conductivity of the round-walled cylinder material.

[0142] The winding and shaft need to be abstracted as a cylinder, and their radial thermal resistance is:

[0143]

[0144] The axial thermal resistance is:

[0145]

[0146] The heat capacity calculation formula for a cylinder is the same as that for a round-walled cylinder.

[0147] Step 104 , selecting temperature nodes of the motor in the thermal network model, and constructing a transient thermal balance equation of the motor based on the temperature nodes.

[0148] According to the simplified Mellor thermal network model, the transient thermal balance equation of the motor is:

[0149]

[0150] In the formula, is the heat capacity matrix, is the thermal conductivity matrix, is the matrix of each temperature node, It is the endogenous heat matrix.

[0151] Establish the thermal network model of permanent magnet synchronous motor as follows Figure 5 As shown in the figure, the overall thermal network has 16 temperature nodes, of which 5 temperature nodes are the midpoint temperatures of the circular wall cylinder structure, and their structures are respectively the stator yoke part iron, the stator tooth part teeth, the rotor part rotor, the housing and stator tooth contact part frame1, and the housing and end air gap contact part frame2; 2 temperature nodes are the cylinder structure temperatures, and their structures are respectively the shaft and rotor contact part shaft1, and the shaft and end air gap contact part shaft2; the thermal resistance of each circular wall cylinder and cylinder can be calculated by the simplified Mellor thermal network model.

[0152] The remaining temperature nodes are the temperatures of the contact surfaces between the motor air gap and each entity. The convection between each air gap and the motor entity is represented by the convection thermal resistance, which is R1~R10 , calculated by the convection thermal resistance formula:

[0153]

[0154] Where h is the heat convection coefficient, and A is the heat convection area between the air gap and the motor entity.

[0155] Step 105 , connecting the electrical model, the endogenous heat model and the thermal network model in sequence to obtain a multi-field coupling model of the motor.

[0156] The multi-field coupling model of the motor is as follows Figure 6 As shown in the figure, according to the motor example, the parameters are set, the thermal resistance, thermal capacity, and heat source are calculated, and then the overall motor simulation is performed. Figure 2 The winding temperature in the motor electrical model shown is T winding In the endogenous heat model, the winding temperature and the end winding temperature are T winding ,T endwinding The temperature values ​​corresponding to the magnetic flux density of the stator yoke and stator teeth are T iron ,T teeth The simulation results are as follows: Figure 7 As shown, from Figure 7 It can be seen that the temperature of all the physical structures of the motor rises first and then tends to stabilize, which is in line with the actual situation; the winding temperature is the highest and the shell temperature is the lowest. The temperature of other structures such as the stator yoke, stator teeth, and rotor is much lower than that of the winding and close to the shell temperature. The reason is that the winding loss in the heat generation of the motor far exceeds other losses, causing the winding temperature to rise rapidly and the steady-state temperature to be high, which is in line with expectations; the rotor and the shaft are closely connected, and the two are relatively large in volume and heat capacity, so the temperatures of the two are very close; the rotor, shaft and winding are relatively close, and it is not easy to dissipate heat inside the motor. The shell is in direct contact with the external environment, with a large heat dissipation area, and the stator is in direct contact with the shell. The heat is dissipated through the shell, so the rotor and shaft temperatures are first lower than the stator and shell temperatures and then gradually rise to exceed the stator and shell temperatures. The established motor multi-field coupling model is similar to the results of other models and finite element calculations, and has high accuracy. At the same time, this solution method can obtain all the technical states inside the motor, and can arbitrarily change the internal parameters, and the solution is fast.

[0157] Step 106, simulating the temperature change during the operation of the motor based on the multi-field coupling model, and updating the motor parameters in the multi-field coupling model using a gradient descent algorithm so that the difference between the simulated temperature and the actual temperature of the motor is less than a preset threshold.

[0158] Since modeling will inevitably deviate from the physical entity, the error between the model output and the reference output will gradually accumulate during the actual operation, and the final error will exceed the acceptable threshold. Therefore, each time the threshold is reached, we need to use the corresponding parameter dynamic update algorithm to optimize the model. The gradient descent algorithm is used in the present invention.

[0159] In the present invention, the overall output of the motor is: The output results that need to be compared are: Respectively represent the temperature at the winding, the end winding temperature, the stator yoke temperature, and the stator tooth temperature. The reference temperature data is defined as: (y1, y2, y3, y4) = (T winding_true ,T endwinding_true ,T iron_true ,T teeth_true ).

[0160] When optimizing it, the parameters in the motor mathematical model that change with the model output are selected as the parameters that need to be updated. In this invention, the adjustable parameters corresponding to the above output results are:

[0161] They represent winding resistance, end winding resistance, stator yoke magnetic flux density, and stator tooth magnetic flux density respectively.

[0162] The remaining non-adjustable parameters are defined as: (x5, x6, …, x n ), then all the internal parameters of the motor are: Relationship between motor output and overall parameters It can be obtained by the above steps.

[0163] The objective function is defined as:

[0164]

[0165] Any adjustable parameter In the algorithm, the data at each step is described as Then the gradient descent method can be used to find the optimal solution:

[0166]

[0167] Using the above formula Update until ε is the set error threshold.

[0168] The specific algorithm process is as follows:

[0169] (1) Calculate the gradient of the k-th step with respect to the adjustable parameters:

[0170]

[0171] (2) The descending direction is the negative direction of the gradient:

[0172]

[0173] (3) Calculate the adjustable parameter value of the k+1th step:

[0174] Right now

[0175]

[0176] In the formula, λ is the simulation step size, which can be set by yourself. If there is an explicit expression, the exact line search step size can be calculated. Then the parameter value of the k+1th step is:

[0177]

[0178] (4) Substitute the parameter values ​​to find the output physical quantities of the k+1 step:

[0179]

[0180] (5) Find the objective function value of step k+1:

[0181]

[0182] (6) Compare whether the objective function meets expectations If yes, exit; otherwise, continue iterating.

[0183] The magnetothermal coupling model of the permanent magnet synchronous motor established above is simulated and the comparison diagram of the winding temperature and the temperature of the stator yoke and teeth is obtained as shown in the figure below. Figure 8 As shown, the red curve represents the temperature of the motor model under normal circumstances without a correction algorithm, and the blue curve represents the externally imported comparison data. It can be seen that without adding a correction algorithm, the errors of the four comparison temperatures of the motor gradually increase with the passage of time, which is in line with the expected error accumulation scenario over time.

[0184] Therefore, in order to make the motor model follow the external data better, the gradient descent algorithm is used to correct it, and the results are as follows Fig. 9 As shown, the corrected output of the selected parameters, namely (R winding ,R endwinding ,B iron ,B teeth ),like Fig.10 As shown. Fig. 9 It can be seen from the figure that when the model is simulated for about 9 seconds, the output error exceeds the set threshold. The parameters are updated according to the algorithm, and then the model output changes. The error with the reference data gradually decreases and finally becomes almost consistent. The operation process and results are in line with expectations. Fig.10 The parameter correction value can be seen in When the error exceeds the threshold, it changes greatly and then stabilizes quickly. Through algorithm iteration, the appropriate correction parameter value is obtained to gradually reduce the output error.

[0185] Compare Figure 8 , Fig. 9 It can be seen that the correction algorithm has a good correction effect on the model output, but because different parameters have different degrees of influence on the motor model, the selection of appropriate proportional coefficients and parameters plays a decisive role in the correction and optimization of the motor model.

[0186] The present invention also provides a motor temperature simulation system, the simulation system comprising:

[0187] Electrical model building module, used to build the electrical model of the motor.

[0188] The intrinsic heat model building module is used to build the intrinsic heat model of the motor.

[0189] The thermal network model building module is used to construct the thermal network model of the motor by equating the motor housing, stator yoke, stator teeth and rotor to a circular wall cylinder and the motor winding and shaft to a cylinder.

[0190] The transient heat balance equation construction module is used to select the temperature nodes of the motor in the thermal network model and construct the transient heat balance equation of the motor based on the temperature nodes.

[0191] The multi-field coupling model building module is used to connect the electrical model, the endogenous heat model and the transient heat balance equation in sequence to obtain a multi-field coupling model of the motor.

[0192] The simulation module is used to simulate the temperature change during the operation of the motor based on the multi-field coupling model, and use the gradient descent algorithm to update the motor parameters in the multi-field coupling model so that the difference between the simulated temperature and the actual temperature of the motor is less than a preset threshold.

[0193] Wherein, the endogenous heat model is:

[0194]

[0195] Among them, G iron is the heat source of the stator yoke, G Fei Generates heat for the stator yoke, G Fei =K ai p Fei m Fei , m Fei is the weight of the stator yoke; K ai is the empirical coefficient for the increase in stator yoke loss; p Feiis the loss of silicon steel sheet per unit mass of the stator yoke, p 10 / 50,i B is the loss of the silicon steel sheet per unit mass of the stator yoke when B = 1T, f0 = 50Hz, iron Indicates the maximum magnetic flux density in the stator yoke, T iron represents the stator yoke temperature, B represents the magnetic flux density, f represents the magnetic field frequency, and f0 represents the rated frequency of the magnetic field;

[0196] G teeth is the heat source of the stator teeth, G Fet Generates heat for the stator teeth, G Fet =K at p Fet m Fet , m Fet is the weight of the stator teeth, K at is the empirical coefficient for the increase in stator tooth loss, p Fet is the stator tooth loss ratio, p 10 / 50,t It represents the loss of silicon steel sheet per unit mass of stator teeth when B = 1T, f0 = 50Hz, B teeth Indicates the maximum magnetic flux density in the stator yoke, T teeth Indicates the stator tooth temperature;

[0197] G rotor is the rotor heat source, P R The permanent magnet generates heat, P R =∫J 2 / σdV, J is the eddy current density of the permanent magnet; σ is the electrical conductivity of the permanent magnet, V is the volume of the permanent magnet, P h Generate heat for the rotor, P h =k1C f πρω m 3 r 4 l, k1 is the roughness coefficient of the rotor surface; r is the rotor radius; l is the axial length of the rotor; C f is the air friction coefficient; ρ is the air density; ω m is the rotor mechanical angular velocity;

[0198] G winding is the winding heat source, i a ,i b ,i c is the three-phase current of the motor, R winding (T winding ) is the temperature T winding Winding resistance, R winding (T winding )=R 0,winding (1+α cu (Twinding -T 15 )), α Cu is the temperature coefficient of conductor resistance; R winding (T winding ) is the temperature T endwinding End winding resistance, T winding is the winding temperature, R 0,winding is the winding resistance at 15°C, T 15 15℃;

[0199] G endwinding is the end winding heat source, R endwinding (T endwinding ) is the temperature T endwinding The end winding resistance, R endwinding (T endwinding )=R 0,endwinding (1+α cu (T endwinding -T 15 )), R 0,endwinding Indicates the end winding resistance at a temperature of 15°C, T endwinding is the end winding resistance temperature.

[0200] The heat capacity calculation formula of the round-wall cylinder and the cylinder in the thermal network model is:

[0201] C=ρ·c p ·V;

[0202] Where C is the heat capacity, ρ is the material density of the round-walled cylinder or cylinder, and c p is the specific heat of the round-walled cylinder or cylinder material, V is the volume of the round-walled cylinder or cylinder;

[0203] The calculation formula for the thermal resistance of a round-walled cylinder is:

[0204]

[0205] Among them, R a is the radial thermal resistance of the round-walled cylinder, R 1r is the axial thermal resistance of the inner wall of the circular cylinder, R 2r is the axial thermal resistance of the outer wall of the round-wall cylinder, r1 and r2 are the inner radius and outer radius of the round-wall cylinder respectively, L is the length of the round-wall cylinder, and k is the thermal conductivity of the round-wall cylinder material;

[0206] The thermal resistance of a cylinder is calculated as:

[0207]

[0208]

[0209] Among them, Rr ' represents the axial thermal resistance of the cylinder, k' represents the thermal conductivity of the cylinder material, L' represents the length of the cylinder, r' represents the radius of the cylinder, R' a Represents the radial thermal resistance of the cylinder.

[0210] The transient heat balance equation is:

[0211] in, represents the heat capacity matrix, C1, C n and C N denote the heat capacities of the 1st, nth and Nth temperature nodes respectively;

[0212] is the thermal conductivity matrix, and They represent the heat conduction quantities of the 1st, nth and Nth temperature nodes respectively;

[0213] is the thermal conductivity matrix, Y1,Y n and Y N They represent the thermal conductance of the 1st, nth and Nth temperature nodes respectively. The thermal conductance of each temperature node is obtained by adding the reciprocal of the thermal resistance of the connecting branches of each temperature node;

[0214] is the endogenous heat matrix, G1, G n and G N They represent the internal heat of the 1st, nth and Nth temperature nodes respectively. When the nth temperature node is located at the stator yoke, G n =G iron , when the nth temperature node is located at the stator tooth G n =G teeth , when the nth temperature node is located at the rotor G n =G rotor , when the nth temperature node is located in the winding G n =G winding , when the nth temperature node is located at the end winding G n =G endwinding .

[0215] The advantages and positive effects of the present invention are:

[0216] (1) A complete multi-field coupling mathematical model of the motor was constructed. Unlike the finite element simulation using commercial software, whose internal logic and mechanism are a "black box", the use of a pure mathematical model to calculate the internal temperature and other technical conditions of the motor can obtain data that is difficult to measure with actual sensors. At the same time, it can obtain a transient solution state that is different from the steady-state solution of finite element analysis.

[0217] (2) The gradient descent algorithm can be used to make the mathematical model follow the physical output, making the model output more realistic.

[0218] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0219] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A motor temperature simulation method, characterized in that: The simulation method comprises the following steps: Build an electrical model of the motor; Construct an endogenous heat model of the motor; The motor housing, stator yoke, stator teeth and rotor are equivalent to a circular wall cylinder, and the motor winding and shaft are equivalent to a cylinder to construct a thermal network model of the motor; Selecting temperature nodes of the motor in the thermal network model, and constructing a transient thermal balance equation of the motor based on the temperature nodes; the transient thermal balance equation is used for calculation of the thermal network model; The electrical model, the endogenous heat model and the thermal network model are sequentially connected to obtain a multi-field coupling model of the motor; Based on the multi-field coupling model, the temperature change during the operation of the motor is simulated, and the motor parameters in the multi-field coupling model are updated using a gradient descent algorithm so that the difference between the simulated temperature and the actual temperature of the motor is less than a preset threshold; The electrical model includes: stator voltage equation, stator flux equation, electromagnetic torque equation, and motor motion equation; The endogenous heat model is: Among them, G iron is the heat source of the stator yoke, G Fei Generates heat for the stator yoke; G teeth is the heat source of the stator teeth, G Fet Generate heat for the stator teeth; G rotor is the rotor heat source, P R The permanent magnet generates heat, P h Generate heat for the rotor; G winding is the winding heat source, i a ,i b ,i c is the three-phase current of the motor, R winding (T winding ) is the temperature T winding Winding resistance when G endwinding is the end winding heat source, R endwinding (T endwinding ) is the temperature T endwinding The end winding resistance.

2. The motor temperature simulation method according to claim 1, characterized in that: The heat generated by the stator yoke is: G Fei =K ai p Fei m Fei , m Fei is the weight of the stator yoke; K ai is the empirical coefficient for the increase in stator yoke loss; p Fei is the loss of silicon steel sheet per unit mass of the stator yoke, p 10 / 50,i B is the loss of the silicon steel sheet per unit mass of the stator yoke when B = 1T, f0 = 50Hz, iron Indicates the maximum magnetic flux density in the stator yoke, T iron represents the stator yoke temperature, B represents the magnetic flux density, f represents the magnetic field frequency, and f0 represents the rated frequency of the magnetic field; The heat generated by the stator teeth is: G Fet =K at p Fet m Fet , m Fet is the weight of the stator teeth, K at is the empirical coefficient for the increase in stator tooth loss, p Fet is the stator tooth loss ratio, p 10 / 50,t It represents the loss of silicon steel sheet per unit mass of stator teeth when B = 1T, f0 = 50Hz, B teeth Indicates the maximum magnetic flux density in the stator yoke, T teeth Indicates the stator tooth temperature; The heat generated by permanent magnets is: P R =∫J 2 / σdV, J is the eddy current density of the permanent magnet; σ is the electrical conductivity of the permanent magnet, V is the volume of the permanent magnet; The heat generated by the rotor is: P h =k1C f πρω m 3 r 4 l, k1 is the roughness coefficient of the rotor surface; r is the rotor radius; l is the axial length of the rotor; C f is the air friction coefficient; ρ is the air density; ω m is the rotor mechanical angular velocity; Temperature is T winding The winding resistance is: R winding (T winding )=R 0,winding (1+α cu (T winding -T 15 )), α Cu is the temperature coefficient of conductor resistance; R winding (T winding ) is the temperature T endwinding End winding resistance, T winding is the winding temperature, R 0,winding is the winding resistance at 15°C, T 15 15℃; Temperature is T endwinding The end winding resistance is: R endwinding (T endwinding )=R 0,endwinding (1+α cu (T endwinding -T 15 )), R 0,endwinding Indicates the end winding resistance at a temperature of 15°C, T endwinding is the end winding resistance temperature.

3. The motor temperature simulation method according to claim 2, characterized in that: The heat capacity calculation formula of the round-wall cylinder and the cylinder in the thermal network model is: C=ρ·c p ·V; Where C is the heat capacity, ρ is the material density of the round-walled cylinder or cylinder, and c p is the specific heat of the round-walled cylinder or cylinder material, V is the volume of the round-walled cylinder or cylinder; The thermal resistance calculation formula of the round wall cylinder is: Among them, R a is the radial thermal resistance of the round-walled cylinder, R 1r is the axial thermal resistance of the inner wall of the circular cylinder, R 2r is the axial thermal resistance of the outer wall of the round-wall cylinder, r1 and r2 are the inner radius and outer radius of the round-wall cylinder respectively, L is the length of the round-wall cylinder, and k is the thermal conductivity of the round-wall cylinder material; The thermal resistance of a cylinder is calculated as: Among them, R r ' represents the axial thermal resistance of the cylinder, k' represents the thermal conductivity of the cylinder material, L' represents the length of the cylinder, r' represents the radius of the cylinder, R' a Represents the radial thermal resistance of the cylinder.

4. The motor temperature simulation method according to claim 3, characterized in that: The transient heat balance equation is: in, represents the heat capacity matrix, C1, C n and C N denote the heat capacities of the 1st, nth and Nth temperature nodes respectively; is the thermal conductivity matrix, Y1,Y n and Y N They represent the thermal conductance of the 1st, nth and Nth temperature nodes respectively. The thermal conductance of each temperature node is obtained by adding the reciprocal of the thermal resistance of the connecting branches of each temperature node; is the temperature node matrix, T1, T n and T N Represent the temperatures of the 1st, nth and Nth temperature nodes respectively; is the endogenous heat matrix, G1, G n and G N They represent the internal heat of the 1st, nth and Nth temperature nodes respectively. When the nth temperature node is located at the stator yoke, G n =G iron , when the nth temperature node is located at the stator tooth G n =G teeth , when the nth temperature node is located at the rotor G n =G rotor , when the nth temperature node is located in the winding G n =G winding , when the nth temperature node is located at the end winding G n =G endwinding .

5. A motor temperature simulation system, characterized in that: The simulation system comprises: Electrical model building module, used to build the electrical model of the motor; An endogenous heat model building module is used to build an endogenous heat model of the motor; A thermal network model building module is used to construct a thermal network model of the motor by equating the motor housing, stator yoke, stator teeth and rotor to a circular wall cylinder, and the motor winding and shaft to a cylinder; A transient heat balance equation construction module, used for selecting temperature nodes of the motor in the thermal network model, and constructing a transient heat balance equation of the motor based on the temperature nodes; the transient heat balance equation is used for calculation of the thermal network model; A multi-field coupling model building module, used to sequentially connect the electrical model, the endogenous heat model and the thermal network model to obtain a multi-field coupling model of the motor; A simulation module, used to simulate the temperature change during the operation of the motor based on the multi-field coupling model, and to update the motor parameters in the multi-field coupling model using a gradient descent algorithm so that the difference between the simulated temperature and the actual temperature of the motor is less than a preset threshold; The electrical model includes: stator voltage equation, stator flux equation, electromagnetic torque equation, and motor motion equation; The endogenous heat model is: Among them, G iron is the heat source of the stator yoke, G Fei Generates heat for the stator yoke; G teeth is the heat source of the stator teeth, G Fet Generate heat for the stator teeth; G rotor is the rotor heat source, P R The permanent magnet generates heat, P h Generate heat for the rotor; G winding is the winding heat source, i a ,i b ,i c is the three-phase current of the motor, R winding (T winding ) is the temperature T winding Winding resistance when G endwinding is the end winding heat source, R endwinding (T endwinding ) is the temperature T endwinding The end winding resistance.

6. The motor temperature simulation system according to claim 5, characterized in that: The heat generated by the stator yoke is: G Fei =K ai p Fei m Fei , m Fei is the weight of the stator yoke; K ai is the empirical coefficient for the increase in stator yoke loss; p Fei is the loss of silicon steel sheet per unit mass of the stator yoke, p 10 / 50,i B is the loss of the silicon steel sheet per unit mass of the stator yoke when B = 1T, f0 = 50Hz, iron Indicates the maximum magnetic flux density in the stator yoke, T iron represents the stator yoke temperature, B represents the magnetic flux density, f represents the magnetic field frequency, and f0 represents the rated frequency of the magnetic field; The heat generated by the stator teeth is: G Fet =K at p Fet m Fet , m Fet is the weight of the stator teeth, K at is the empirical coefficient for the increase in stator tooth loss, p Fet is the stator tooth loss ratio, p 10 / 50,t It represents the loss of silicon steel sheet per unit mass of stator teeth when B = 1T, f0 = 50Hz, B teeth Indicates the maximum magnetic flux density in the stator yoke, T teeth Indicates the stator tooth temperature; The heat generated by permanent magnets is: P R =∫J 2 / σdV, J is the eddy current density of the permanent magnet; σ is the electrical conductivity of the permanent magnet, V is the volume of the permanent magnet; The heat generated by the rotor is: P h =k1C f πρω m 3 r 4 l, k1 is the roughness coefficient of the rotor surface; r is the rotor radius; l is the axial length of the rotor; C f is the air friction coefficient; ρ is the air density; ω m is the rotor mechanical angular velocity; Temperature is T winding The winding resistance is: R winding (T winding )=R 0,winding (1+α cu (T winding -T 15 )), α Cu is the temperature coefficient of conductor resistance; R winding (T winding ) is the temperature T endwinding End winding resistance, T winding is the winding temperature, R 0,winding is the winding resistance at 15°C, T 15 15℃; Temperature is T endwinding The end winding resistance is: R endwinding (T endwinding )=R 0,endwinding (1+α cu (T endwinding -T 15 )), R 0,endwinding Indicates the end winding resistance at a temperature of 15°C, T endwinding is the end winding resistance temperature.

7. The motor temperature simulation system according to claim 6, characterized in that: The heat capacity calculation formula of the round-wall cylinder and the cylinder in the thermal network model is: C=ρ·c p ·V; Where C is the heat capacity, ρ is the material density of the round-walled cylinder or cylinder, and c p is the specific heat of the round-walled cylinder or cylinder material, V is the volume of the round-walled cylinder or cylinder; The calculation formula for the thermal resistance of a round-walled cylinder is: Among them, R a is the radial thermal resistance of the round-walled cylinder, R 1r is the axial thermal resistance of the inner wall of the circular cylinder, R 2r is the axial thermal resistance of the outer wall of the round-wall cylinder, r1 and r2 are the inner radius and outer radius of the round-wall cylinder respectively, L is the length of the round-wall cylinder, and k is the thermal conductivity of the round-wall cylinder material; The thermal resistance of a cylinder is calculated as: Among them, R r ' represents the axial thermal resistance of the cylinder, k' represents the thermal conductivity of the cylinder material, L' represents the length of the cylinder, r' represents the radius of the cylinder, R' a Represents the radial thermal resistance of the cylinder.

8. The motor temperature simulation system according to claim 7, characterized in that: The transient heat balance equation is: in, represents the heat capacity matrix, C1, C n and C N denote the heat capacities of the 1st, nth and Nth temperature nodes respectively; is the thermal conductivity matrix, Y1,Y n and Y N They represent the thermal conductance of the 1st, nth and Nth temperature nodes respectively. The thermal conductance of each temperature node is obtained by adding the reciprocal of the thermal resistance of the connecting branches of each temperature node; is the temperature node matrix, T1, T n and T N Represent the temperatures of the 1st, nth and Nth temperature nodes respectively; is the endogenous heat matrix, G1, G n and G N They represent the internal heat of the 1st, nth and Nth temperature nodes respectively. When the nth temperature node is located at the stator yoke, G n =G iron , when the nth temperature node is located at the stator tooth G n =G teeth , when the nth temperature node is located at the rotor G n =G rotor , when the nth temperature node is located in the winding G n =G winding , when the nth temperature node is located at the end winding G n =G endwinding .

Images