An internal temperature prediction method and system for an aviation three-stage generator

Abstract

The application discloses an internal temperature prediction method and system of an aviation three-stage generator, and the prediction method comprises the following steps: S1: generating a fitting prediction model based on a motor operating state and a busbar side output voltage, current and harmonic content and a three-stage motor internal loss and distribution; S2: constructing a heat transfer model of the aviation three-stage starting generator; distributing the distributed heat source of the aviation three-stage starting generator to form a tooth tip surface heat source based on the step S1, and arranging a plurality of temperature measuring points at the axial position of the main generator shell; taking the measuring point as the origin, and establishing a thermal path in the radial direction of the motor and pointing to the axial direction; S3: establishing an orthogonal reduction mapping model of the stator tooth tip surface heat source and the rotor single winding outer surface heat source based on the POD method; and S4: obtaining the rotor winding outer surface temperature distribution based on the orthogonal reduction mapping model in the step S3 and combining the tooth tip surface heat source distribution formed in the step S2. The application realizes reliable prediction of the internal temperature of the aviation three-stage generator.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromechanical monitoring, and particularly relates to an internal temperature prediction method and system for an aviation three-stage generator. BACKGROUND

[0002] Due to the complex structure of the aviation three-stage generator and the nonlinear distribution of the temperature field, the internal temperature of the aviation three-stage generator always presents a black box state, and there is no intuitive detection method to directly explore the internal temperature condition. Moreover, there is no good early warning mechanism for the temperature change of the internal parts during the processing. Therefore, the internal temperature of the key components of the aviation generator is predicted to determine the specific conditions of the internal temperature and the surface temperature, so as to ensure the safe operation of the generator and make a timely response to abnormal temperature.

[0003] Therefore, a method and system for corresponding relationship between the internal key components and the shell temperature of the generator are needed to improve the accuracy of evaluating the severity of internal heat loss and take necessary maintenance measures in time to avoid overheating failure, which has important significance for ensuring safe and stable operation. SUMMARY

[0004] The application aims to solve the technical problems of the prior art, and provides an internal temperature prediction method and system for an aviation three-stage generator.

[0005] To achieve the above technical purpose, the technical solution adopted by the application is as follows:

[0006] An internal temperature prediction method for an aviation three-stage generator, which takes the running state of the aviation three-stage generator, the monitored value of the power quality of the bus bar, the temperature value of the specific measuring point of the machine shell, the flow and pressure of the cooling oil tank inlet and outlet as input parameters, and predicts the temperature parameters of the key components of the main generator and the main exciter of the starting generator; the prediction method comprises the following steps:

[0007] S1: electromagnetic finite element calculation is performed under the full task profile, an isogram is drawn based on the simulation loss distribution cloud picture, and the position of the key heat source of the aviation three-stage starting generator under different working conditions is determined according to the isogram, the three-dimensional result of the heat source loss is reduced in order, and a fitting prediction model based on the running state of the motor and the output voltage, current and harmonic content of the bus bar side and the distribution and loss of the three-stage motor is generated;

[0008] S2: a heat transfer model of the aviation three-stage starting generator is constructed; the distributed heat source of the aviation three-stage starting generator is simplified to form a tooth tip surface heat source based on step S1, and multiple temperature measuring points are arranged at the axial position of the main generator shell; a thermal path is established in the radial direction of the motor to the axis center with the measuring point as the origin;

[0009] S3: a temperature field calculation model of the motor stable working condition under the full task profile is performed, the highest single tooth tip surface temperature distribution of the stator and the rotor winding outer surface temperature distribution are extracted, the tooth tip surface temperature cloud chart and the rotor winding outer surface temperature cloud chart are respectively divided into multiple parts from the axial direction, and the midpoint temperature values of each part are extracted, and an orthogonal reduction mapping model of the stator tooth tip surface heat source and the rotor single winding outer surface heat source is established based on the POD method;

[0010] S4: based on the orthogonal reduction mapping model in S3, the tooth tip surface heat source distribution formed in S2 is combined to obtain the rotor winding outer surface temperature distribution.

[0011] Preferably, the motor operating state in S1 has three-phase starting, single-phase starting or power generation.

[0012] Preferably, multiple temperature measuring points are arranged in the axial position of the main generator shell in S2, specifically 6n+4, and n represents the number of circumferential spiral flow channels.

[0013] Preferably, the tooth tip surface temperature cloud chart and the rotor winding outer surface temperature cloud chart are respectively divided into multiple parts from the axial direction in S3, specifically 6n+4, and n represents the number of circumferential spiral flow channels.

[0014] Preferably, the heat path established in S2 includes in turn: a shell thermal resistance, a flow channel reduced cold source, a core thermal resistance, a motor core tooth and winding reduced heat source, a tooth tip and tooth tip surface heat source.

[0015] The application also discloses an internal temperature prediction system of an aviation three-stage generator.

[0016] The aviation three-stage starting generator comprises a yoke part and a tooth part of a main generator stator core, a stator winding and a rotor winding.

[0017] The oil supply system comprises an oil tank and an oil pump, the outlet and inlet of the oil tank are connected with the aviation three-stage starting generator cooling system to form a cooling circulation loop, and an oil supply inlet and outlet flow and pressure monitoring system is arranged at the connection between the oil tank and the motor;

[0018] The aviation three-stage starting generator cooling system comprises a motor oil cooling jacket, a rotor shaft, a liquid delivery pipeline, an oil supply tank, an oil pump and a pipeline switch valve.

[0019] The shell temperature measurement system comprises multiple temperature sensors, and multiple measuring points are arranged in the axial direction of the highest point of the aviation three-stage starting generator shell; temperature sensors are used for temperature value measurement.

[0020] Preferably, the multiple measuring points are arranged on the highest point of the aviation three-stage starter generator shell in the axial direction, specifically 6n+4, n is the number of circumferential spiral flow channels; that is, 6n temperature measuring points are evenly arranged on the axial length covered by the shell flow channel, and two temperature measuring points are arranged on the front and rear of the outer side of the shell corresponding to the main generator stator core.

[0021] Preferably, the temperature sensor is a K-type thermocouple.

[0022] Preferably, the computer aggregates the data of the shell temperature measuring system and the oil supply inlet and outlet flow and pressure monitoring system, controls the operation of the oil supply system, and displays the data of the shell temperature measuring system and the oil supply inlet and outlet flow and pressure monitoring system after processing and analysis.

[0023] The present application has the following beneficial effects:

[0024] After adopting the internal temperature prediction method and system of the aviation three-stage generator of the present application, the temperature distribution of the key components with complex structure characteristics in the motor is calculated and predicted by using the real-time data of the motor which is easy to collect. The prediction algorithm is based on the real physical structure of the motor, which can well fit the nonlinearity caused by the magnetic saturation of the motor. The internal configuration of the motor and the coupling effect of multiple physical fields are fully considered, and the motor is simplified. The present application does not need to consider the anisotropy of the heat conduction of the motor, and provides a convenient and reliable temperature calculation method with low time lag, which can effectively improve the accuracy of the evaluation of the severity of the internal heat loss of the motor. The present application innovatively proposes a rotor temperature reduction model taking the stator surface heat source as the independent variable. The model is based on the motor's electric energy output data, temperature acquisition data, flow acquisition data and considers the simulation calculation of multiple physical fields, and is corrected and iterated. The model has a certain accuracy and can provide reliable prediction information. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the internal temperature prediction system of the aviation three-stage generator of the present application.

[0026] Figure 2 It is a schematic diagram of the internal temperature prediction system of the aviation three-stage generator of the present application.

[0027] Figure 3 It is a schematic diagram of the internal temperature prediction system of the aviation three-stage generator of the present application.

[0028] Figure 4 It is a schematic diagram of the internal temperature prediction method of the aviation three-stage generator of the present application.

[0029] Figure 5It is a stator surface heat source mapping rotor surface heat source schematic diagram of an internal temperature prediction method of an aviation three-stage generator. DETAILED DESCRIPTION

[0030] The embodiment of the application is further described in detail below with reference to the accompanying drawings.

[0031] An internal temperature prediction method of an aviation three-stage generator, taking the operating state of the aviation three-stage generator, the monitored value of the power quality at the bus bar, the temperature value of the specific measuring point of the casing, the flow and pressure at the inlet and outlet of the cooling oil tank as input parameters, the temperature parameters of the key components of the main generator and the main exciter of the starting generator are predicted; the prediction method comprises the following steps:

[0032] S1: electromagnetic finite element calculation under the full task profile is performed, the contour lines are drawn based on the simulation loss distribution cloud diagram, and the positions of the key heat sources of the aviation three-stage starting generator under different working conditions are determined, the three-dimensional results of the heat source loss are reduced in order, and a fitting prediction model based on the motor operating state and the output voltage, current and harmonic content of the bus bar side and the distribution and loss of the three-stage generator is generated;

[0033] S2: a heat transfer model of the aviation three-stage starting generator is constructed; the distributed heat source of the aviation three-stage starting generator is simplified to form a tooth tip surface heat source based on step S1, and a plurality of temperature measuring points are arranged at the axial position of the main generator shell; a thermal path is established in the radial direction of the motor with the measuring point as the origin and pointing to the axial direction;

[0034] S3: a temperature field calculation model of the motor under stable working conditions of the full task profile is performed, the highest single tooth tip surface temperature distribution of the stator and the outer surface temperature distribution of the rotor winding are extracted, the tooth tip surface temperature cloud diagram and the outer surface temperature cloud diagram of the rotor winding are respectively divided into multiple parts from the axial direction, and the midpoint temperature values of each part are extracted, and a orthogonal reduction mapping model of the stator tooth tip surface heat source and the outer surface heat source of the single winding of the rotor is established based on the POD method;

[0035] S4: based on the orthogonal reduction mapping model in S3, the tooth tip surface heat source distribution formed in S2 is combined to obtain the outer surface temperature distribution of the rotor winding.

[0036] In specific implementation, the motor operating state in S1 has three-phase starting, single-phase starting or power generation.

[0037] In specific implementation, in S2, a plurality of temperature measuring points are arranged at the axial position of the main generator shell, specifically 6n+4, and n represents the number of circumferential spiral flow channels.

[0038] In specific implementation, in S3, the tooth tip surface temperature cloud diagram and the outer surface temperature cloud diagram of the rotor winding are respectively divided into multiple parts from the axial direction, specifically 6n+4, and n represents the number of circumferential spiral flow channels.

[0039] In the implementation, the thermal path established in S2 comprises, in sequence, a casing thermal resistance, a flow channel reduced cold source, a core thermal resistance, a motor core tooth and winding reduced heat source, a tooth tip and tooth tip surface heat source.

[0040] Referring to Figure 1 The application further discloses an internal temperature prediction system of an aviation three-stage generator, which comprises an aviation three-stage starting generator and a cooling system thereof, a casing temperature measurement system, an oil supply system, an oil supply inlet and outlet flow and pressure monitoring system and a computer.

[0041] The aviation three-stage starting generator comprises a yoke and tooth portion of a main generator stator core, a stator winding and a rotor winding.

[0042] The oil supply system comprises an oil tank and an oil pump, the outlet and inlet of the oil tank are connected with the cooling system of the aviation three-stage starting generator to form a cooling circulation loop, and an oil supply inlet and outlet flow and pressure monitoring system is arranged at the connection between the oil tank and the motor.

[0043] The cooling system of the aviation three-stage starting generator comprises a motor oil cooling jacket, a rotor shaft, a liquid delivery pipeline, an oil supply tank, an oil pump and a pipeline switch valve.

[0044] The casing temperature measurement system comprises a plurality of temperature sensors, a plurality of measurement points are arranged on the uppermost point of the casing of the aviation three-stage starting generator in the axial direction, and the temperature sensors are used to measure the temperature values.

[0045] Referring to Figure 2 In the implementation, the plurality of measurement points arranged on the uppermost point of the casing of the aviation three-stage starting generator in the axial direction are specifically 6n+4, n is the number of circumferential spiral flow channels, i.e. 6n temperature measurement points are arranged on the casing flow channel in the axial length, and two temperature measurement points are arranged in front of and behind the casing outside corresponding to the main generator stator core.

[0046] In the implementation, the temperature sensor is a K-type thermocouple.

[0047] In the implementation, the computer collects the data of the casing temperature measurement system and the oil supply inlet and outlet flow and pressure monitoring system, controls the operation of the oil supply system, and displays the data of the casing temperature measurement system and the oil supply inlet and outlet flow and pressure monitoring system after processing and analysis.

[0048] Embodiment one:

[0049] In the application, referring to Figure 3 Step 1: Simplify the structure of the aviation three-stage starting generator: simplify the spiral flow channel of the oil cooling jacket into an axial cylinder structure, and simplify the stator winding and tooth slot structure into a homogeneous cylinder structure.

[0050] Step 2: Perform electromagnetic finite element calculation under the full task profile, draw contour lines based on the simulation loss distribution cloud map, and determine the stator iron loss, stator winding copper loss, and rotor winding copper loss of the aviation three-stage starter generator under different working conditions, and generate a heat source database with the motor operating state (three-phase starting, single-phase starting or generating) and the output voltage, current and harmonic content of the busbar side as the independent variables, and the loss value of the key heat source position in the three-stage motor as the output.

[0051] Step 3: Take the temperature measuring point outside the casing as the starting point to build a thermal circuit model of the aviation three-stage starter generator. Referring to Figure 4 , a thermal circuit is established in the radial direction of the motor towards the center: the thermal circuit is the casing measuring point temperature value, the casing thermal resistance, the flow channel reduced cold source, the iron core thermal resistance, the motor iron core tooth and winding reduced heat source, the tooth tip, and the tooth tip surface heat source. The calculation is as follows:

[0052]

[0053] Where: l 机壳 is the radial length of the casing, which is obtained according to the motor design parameters; λ 机壳 is the radial thermal conductivity of the casing, which is obtained according to the motor design parameters;

[0054] S0 = ΔL x ΔL

[0055] Where: S0 is the area of the square region represented by each measuring point. It should be noted that the square regions represented by each measuring point are in contact with each other but not overlapping.

[0056] ΔL = the length of the area represented by each casing measuring point. For example, the length of the iron core of a three-stage main generator is 120 mm, and there are 12 spiral flow channels in the casing oil cooling jacket, so the area represented by each measuring point is 1 mm or 1.5 mm.

[0057]

[0058]

[0059] Where: α is the correction coefficient of the reduced cold source;

[0060] ΔT is the temperature value at the inlet and outlet of the motor cooling system;

[0061] c p is the local specific heat capacity of the cooling medium;

[0062] G is the mass flow rate of the oil cooling system;

[0063] ρ is the local density of the cooling medium;

[0064] V 归算流道体积 is the reduced value of the area occupied by the oil-cooled stator core in step 1 simplified as a barrel configuration;

[0065]

[0066] wherein: l 铁心 is the radial length of the stator core yoke, obtained according to motor design parameters;

[0067] λ 铁心 is the radial thermal conductivity of the stator core yoke, obtained according to motor design parameters;

[0068]

[0069] wherein: p 铁损+铜损 is the parameter value in the loss database based on step 2;

[0070] V 轴向绕组 +V 轴向铁心齿 is the reduced value of the area occupied by the stator core teeth and winding in step 1 simplified as a barrel configuration;

[0071] L 齿 is the radial length of the core teeth, obtained according to motor design parameters;

[0072]

[0073] wherein: l 齿 is the actual radial length of the core teeth, obtained according to motor design parameters;

[0074] l 绕组 is the actual radial length of the winding, obtained according to motor design parameters, wherein l 齿 = l 绕组 = L 齿 ;

[0075] S 0绕组 is the area occupied by the winding in the measurement point characteristic area, obtained according to winding wire gauge parameters;

[0076] S 0齿 is the area occupied by the teeth in the measurement point characteristic area, represented by the area of the stator tooth root;

[0077]

[0078] wherein l 齿尖 is the actual radial length of the winding, obtained according to motor design parameters;

[0079] λ 铁心 is the radial thermal conductivity of the stator core yoke, obtained according to motor design parameters.

[0080] Step 4: using function and using nlinfit in matlab to establish fitting function based on actual measured values: mass flow rate G of oil tank, inlet pressure P in and cold source coefficient a.

[0081] G is the mass flow rate of the oil tank;

[0082] P in is the mass flow rate of the oil tank;

[0083] a, b and c are parameters that need to be fitted.

[0084] Step 5: perform temperature field calculation model of motor stable working condition under full task profile, extract single tooth tip surface temperature distribution of stator and rotor winding outer surface temperature distribution, divide tooth tip surface temperature cloud chart and rotor winding outer surface temperature cloud chart into 6n+4 parts from axial direction (n is the number of circumferential spiral flow channel), and extract the midpoint temperature value of each part, see Figure 5 , based on POD method to establish orthogonal reduction mapping model of stator tooth tip surface heat source and rotor single winding outer surface heat source, the specific process is as follows:

[0085] Step 5.1: the tooth tip surface heat source and winding outer surface heat source calculated by finite element method under each working condition are taken as n x m dimensional real matrix S as the function space of reduction model, and SVD decomposition is carried out;

[0086] Step 5.2: the left and right singular matrices, singular value diagonal matrix obtained after decomposition are as follows, and have:

[0087] σ1≥σ2≥…σ p , p = min(m, n)

[0088] U = [φ1…φ m ]

[0089] Z = [ψ1…ψ n ]

[0090] Σ = diag(σ1,…σ p )

[0091] Step 5.3: the data on tooth tip and winding outer surface heat source nodes under different working conditions are represented by S(μi).

[0092] Step 5.4: reduce n x m dimensional matrix to selected k dimension, get orthogonal reduction model as follows:

[0093] V = [ξ1…ξ k ]

[0094]

[0095]

[0096] Step 5.5: multiply the finite element matrix in the surface heat source model with the matrix composed of each base function as the reduced order solution matrix and store it.

[0097] Step 5.6: take the experimental calculation value of the stator surface heat source node in step 2 as input, directly solve the result as the base function coefficient, and finally obtain the distribution of the rotor winding outer surface heat source.

[0098] The internal temperature prediction method and system of the aviation three-stage generator provided by the application calculate and predict the temperature distribution of the key components with complex structure characteristics in the motor interior by using the real-time data of the motor exterior which is easy to collect. The prediction algorithm is based on the real physical structure of the motor and can well fit the nonlinearity caused by the magnetic saturation equivalent effect of the motor. The motor is simplified by fully considering the internal configuration and the multi-physical field coupling effect. The method does not need to consider the anisotropy of the motor heat conduction, provides a convenient and reliable temperature calculation method with low time lag, and can effectively improve the evaluation accuracy of the severity of the motor internal heat loss. The application innovatively proposes a rotor temperature reduction model taking the stator surface heat source as the independent variable. The model is based on the motor power output data, temperature collection data and flow collection data and considers the simulation calculation of the multi-physical field, and is corrected and iterated. The model has a certain accuracy and can provide reliable prediction information.

[0099] Although the application has been described in detail in the above with general description and specific embodiments, some modifications or improvements can be made on the basis of the application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the application, all belong to the scope of protection claimed by the application.

Claims

1. A method of predicting internal temperature of an aircraft three-phase generator, characterized by: The method comprises the following steps: S1: electromagnetic finite element calculation is performed under the full task profile, an isogram is drawn based on the simulation loss distribution cloud picture, the positions of the key heat sources of the aviation three-stage starting generator under different working conditions are determined, the three-dimensional results of the heat source loss are reduced, and a fitting prediction model is generated based on the motor operating state and the busbar side output voltage, current and harmonic content and the internal loss and distribution of the three-stage motor; S2: a heat transfer model of the aviation three-stage starting generator is constructed; the distributed heat source of the aviation three-stage starting generator is simplified into a tooth tip surface heat source based on step S1, and a plurality of temperature measuring points are arranged at the axial positions of the main generator shell; A thermal path is established in the radial direction of the motor and pointing to the axial direction; The thermal path established in S2 comprises in sequence: the shell thermal resistance, the flow channel reduced cold source, the core thermal resistance, the motor core tooth and winding reduced heat source, the tooth tip and tooth tip surface heat source, and the calculation formula is as follows: ， wherein: is the radial length of the enclosure; is the radial thermal conductivity of the enclosure; is the area of the nearby square region characterized for each measurement point, , is the side length of the nearby region characterized for each enclosure measurement point; ， ， wherein: α is the correction factor for the reduced heat sink; is the radial length of the stator core yoke; is the temperature value at the outlet of the motor cooling system; is the local specific heat capacity of the cooling medium; is the mass flow of the oil cooling system; is the local density of the cooling medium; is the reduced value of the oil cooling housing area simplified as a barrel configuration; is the pressure at the inlet of the oil tank; a , b , c is the fitting parameter; ， wherein: is the radial heat transfer coefficient of the stator core yoke portion; ， wherein: is the parameter value in the loss database; , is the reduced value of the stator core tooth and winding area simplified as a barrel configuration; is the radial length of the core tooth portion; ， Wherein: is the actual radial length of the tooth portion; is the actual radial length of the winding, is the area occupied by the winding in the area represented by the measuring point; is the area occupied by the tooth portion in the area represented by the measuring point;​​​ ， wherein Lr is the actual radial length of the winding; S3: a temperature field calculation model of the motor under the stable working condition of the full task profile is performed, the highest single tooth tip surface temperature distribution of the stator and the rotor winding outer surface temperature distribution are extracted, the tooth tip surface temperature cloud picture and the rotor winding outer surface temperature cloud picture are respectively divided into multiple parts from the axial direction, and the midpoint temperature values of each part are extracted, and an orthogonal reduction mapping model of the stator tooth tip surface heat source and the rotor single winding outer surface heat source is established based on the POD method; S4: based on the orthogonal reduction mapping model in S3, the tooth tip surface heat source distribution formed in S2 is combined to obtain the temperature distribution of the outer surface of the rotor winding.

2. The method of claim 1, wherein: The motor operating state in S1 has three-phase starting, single-phase starting or power generation.

3. The method of claim 1, wherein: In S2, a plurality of temperature measuring points are arranged at the axial positions of the main generator shell, specifically 6n+4, and n represents the number of circumferential spiral flow channels.

4. The method of claim 1, wherein: In S3, the tooth tip surface temperature cloud picture and the rotor winding outer surface temperature cloud picture are respectively divided into multiple parts from the axial direction, specifically 6n+4, and n represents the number of circumferential spiral flow channels.

5. An internal temperature prediction system of an aircraft three-stage generator for implementing the internal temperature prediction method according to claim 1, characterized in that: The system comprises an aviation three-stage starting generator and its cooling system, a shell temperature measurement system, an oil supply system, an oil outlet and inlet flow and pressure monitoring system, and a computer; The aviation three-stage starting generator comprises the yoke and tooth parts of the main generator stator core, the stator winding and the rotor winding; The oil supply system comprises an oil tank and an oil pump, the outlet and inlet of the oil tank are connected with the aviation three-stage starting generator cooling system to form a cooling circulation loop, and an oil outlet and inlet flow and pressure monitoring system is arranged at the connection between the oil tank and the motor; The aviation three-stage starting generator cooling system comprises a motor oil cooling jacket, a rotor shaft, a liquid delivery pipeline, an oil supply tank, an oil pump and a pipeline switch valve; The shell temperature measurement system comprises a plurality of temperature sensors, a plurality of measuring points are arranged on the uppermost point of the aviation three-stage starting generator shell in the axial direction, and the temperature sensors are used for temperature measurement.

6. An internal temperature prediction system for an aircraft three-phase generator as claimed in claim 5, characterized in that: The specific number of the plurality of measuring points is 6n+4, n is the number of circumferential spiral flow channels; that is, 6n temperature measuring points are evenly arranged on the axial length covered by the shell flow channel, and two temperature measuring points are arranged respectively in front of and behind the outer side of the main generator stator core.

7. An internal temperature prediction system for an aircraft three-phase generator as defined in claim 5, wherein: The computer aggregates the data of the shell temperature measuring system and the oil supply inlet and outlet flow and pressure monitoring system, controls the operation of the oil supply system, and displays the data of the shell temperature measuring system and the oil supply inlet and outlet flow and pressure monitoring system after processing and analysis.

Images