Device and method for measuring rotor temperature
By forming appropriate orifices in the stator of the electric motor, and placing the sensor with the reflected radiation of the rotor and the stator for temperature calculation, the problem of not being able to directly measure the rotor temperature in the prior art is solved, and high-precision non-contact Temperature measurement, suitable for all motor types.
Patent Information
- Application Number
- CN202110343221.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2020-12-03
- Filing Date
- 2021-03-30
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2041-03-30
AI Technical Summary
The prior art cannot directly measure the rotor surface temperature during the operation of the electric motor, especially due to the inability to access the rotor, resulting in inaccurate temperature measurements, and traditional methods require stopping the motor power for measurements, which cannot be applied to the rotor of the induction motor.
A device and method are designed to use air gaps by forming first and second orifices in a stator, placing sensors to directly measure the rotor surface temperature and using infrared sensors to perform temperature calculations in combination with reflected radiation from the rotor surface and the stator surface. The structure is measured in a non-contact manner and defines an infrared radiation path through a stepped orifice to improve measurement accuracy.
Accurate measurement of rotor temperature during electric motor operation, avoiding the disadvantage of stopping motor power, improving the accuracy and reliability of temperature measurement, and is suitable for all types of motors, including induction motors.
Smart Images
Figure CN114665669B_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to measuring the temperature of an electric motor rotor during operation of the electric motor. Background Art
[0002] Electric motors used to power electric vehicles, including hybrid electric vehicles, require accurate temperature measurement during operation to provide optimal motor performance, avoid performance-limiting thermal overload, and maximize motor life. The rotor is the most important component for tracking temperature conditions during operation. However, existing techniques for measuring motor temperature cannot directly measure the temperature of the rotor surface area in the air gap during operation due to a lack of access to the rotor.
[0003] Currently, production motors rely on temperature estimators based on thermal resistance networks to provide input data to the vehicle controller. Known temperature estimators based on temperature measurement networks include the back-EMF method, which indirectly estimates the overall temperature of the permanent magnet motor's rotor magnets. The main disadvantage of the back-EMF method is that it requires stopping the power input to the motor for a predetermined period, which is undesirable. Induction motors do not include permanent magnets in their rotors, and currently there is no suitable method to measure rotor temperature.
[0004] Therefore, while current motor temperature measurement systems perform their intended purpose, a need exists for a new and improved system and method for measuring the temperature of an electric motor rotor during operation of the electric motor. Summary of the Invention
[0005] According to various aspects, an apparatus for measuring the temperature of a motor vehicle rotor includes a motor having a rotor. Also included is a stator within which the rotor is positioned. A first aperture or opening extends through the stator. A sensor is positioned aligned with the first aperture to sense the temperature of at least one surface of the rotor within its line of sight.
[0006] In another aspect of the present disclosure, the first aperture defines a stepped aperture extending through the stator.
[0007] In another aspect of the present disclosure, a second aperture or opening extends through the housing supporting the sensor, the first aperture having a smaller diameter than the second aperture.
[0008] In another aspect of the present disclosure, a stator surface is visible to the sensor through the second aperture.
[0009] In another aspect of the present disclosure, the first aperture is coaxially aligned with the second aperture and is within a line of sight of the sensor.
[0010] In another aspect of the present disclosure, an air gap is created between the lens of the sensor and the rotor surface, which minimizes heat transfer from the rotor to the sensor and provides non-contact rotor temperature measurement in the air gap.
[0011] In another aspect of the present disclosure, the air gap is also located between a housing supporting the sensor and a rotor surface.
[0012] In another aspect of the present disclosure, an air gap is further provided between the lens and the stator surface of the sensor.
[0013] In another aspect of the present disclosure, the stator includes a plurality of teeth, and the aperture extends through at least one of the plurality of teeth.
[0014] In another aspect of the present disclosure, the sensor may be an infrared detector.
[0015] According to various aspects, a method for measuring the temperature of a motor vehicle rotor of a motor having a rotor includes positioning the rotor within a stator; creating a first aperture or opening extending through the stator; aligning a sensor with the first aperture; and operating the sensor to sense a temperature of at least one surface of the rotor.
[0016] In another aspect of the present disclosure, the method further includes forming the first aperture as a stepped aperture extending through the stator, the stepped aperture including a second aperture or opening extending through a housing supporting the sensor, wherein a stator surface is visible to the sensor through the second aperture.
[0017] In another aspect of the present disclosure, according to an embodiment, the method further includes selecting the sensor to be an infrared detector that senses a surface of the rotor and a surface of the stator.
[0018] In another aspect of the present disclosure, the method further includes extending the aperture through at least one of the plurality of teeth of the stator.
[0019] In another aspect of the present disclosure, the method further includes receiving, by the sensor, a total radiation W tot , the total radiation W tot Equal to [emission to the surroundings reflected by the target defining the rotor surface] + [emission by the target] + [absorption by the atmosphere and external optics].
[0020] In another aspect of the present disclosure, the method further comprises: assuming that the initial reflected sensing temperature T_refl_initial of the rotor surface is equal to the motor oil temperature T oil , or equal to the stator temperature when motor oil is not used as cooling oil; calculate the reflected temperature T refl , which is equal to the constant Crefl Multiply by [rotor temperature T rotor Stator temperature T stator ] divided by 2.
[0021] In another aspect of the present disclosure, the method further comprises: using the calculated reflected temperature T refl Replace the initial reflection sensing temperature T_refl_initial of the rotor surface; refl Perform at least a second iteration of the calculation.
[0022] According to various aspects, a method for measuring the temperature of a motor rotor of a motor vehicle having a rotor and a stator comprises: aligning an infrared sensor with a surface of the rotor; in an obtaining step, obtaining a plurality of items from vehicle sensor data, the data including the motor oil temperature T oil Or the stator temperature when cooling oil is not used, the infrared sensor stator temperature signal IR_rotor_raw, the infrared sensor rotor signal IR_rotor_raw, the rotor object emissivity ε _ obj, predetermined transmittance τ_atm, atmospheric temperature T_atm and temperature at the sensor T_optic, where it is assumed that the initial reflection sensing temperature T_refl_initial is equal to the motor oil temperature T oil If the motor oil temperature is 54T oil If the motor oil temperature is less than 40°C, the first temperature calibration is performed. oil If it is equal to or greater than 40°C, perform the second temperature calibration; calculate the reflected temperature T refl The value of the reflected temperature T refl The value is equal to the constant C refl Multiply by [rotor temperature T rotor Stator temperature T stator ] divided by 2.
[0023] In another aspect of the present disclosure, the method further comprises, upon completion of the reflected temperature T refl After the calculation of T, by returning to the obtaining step and using the calculated T refl The value of is replaced by the initial assumption that it is equal to the motor oil temperature T of the motor oil At least a second iteration is performed based on the initial reflected sensing temperature T_refl_initial.
[0024] In another aspect of the present disclosure, the method further includes extending a stepped aperture in a stator lamination, the stepped aperture defining an infrared radiation path from an infrared sensor to enable simultaneous infrared sensing on a surface of the rotor and on a surface of the stator.
[0025] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
[0027] Figure 1 is a front view of a motor having an apparatus and method for measuring rotor temperature according to an exemplary aspect;
[0028] Figure 2 It is along Figure 1 a cross-sectional end view taken at section 2 of ;
[0029] Figure 3 is a flowchart showing steps for performing the method of the present disclosure;
[0030] Figure 4 is a front view of a motor having first and second sensors of the present disclosure. DETAILED DESCRIPTION
[0031] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
[0032] Reference Figure 1 According to various aspects, an apparatus and method 10 for measuring rotor temperature includes a motor 12 having a rotor 14 for rotating an output shaft 16 relative to an axis of rotation 18. The rotor 14 is positioned with a stator 20. In order to accurately and directly determine the rotor temperature T at the rotor surface 22, rotor A first through hole 24 is formed through the stator 20. The first through hole 24 provides a line of sight to the rotor surface 22. In order to accurately and directly determine the stator temperature T stator , a second through hole 26 is formed through a housing 28 supporting the stator 20. According to various aspects, the first through hole 24 and the second through hole 26 are coaxially aligned on a common axis 30. The second through hole 26 provides a line of sight to the stator surface 32. In order to determine the rotor temperature T at the rotor surface 22 rotor and the stator temperature T at the stator surface 32 stator A sensor 34 , such as an infrared sensor, is mounted on the housing 28 using a sensor mount 36 .
[0033] See also Figure 2 And see again Figure 1, the stator 20 includes a plurality of stator laminations 38, each of which has an outer ring 40 and a plurality of inwardly extending lamination teeth 42. A plurality of stator slots 44 are individually disposed between the lamination teeth 42. Stator windings 46, for example, made of copper wire, are located within the stator slots 44. A first through-hole 24 is formed, for example, by passing through the center of an exemplary lamination tooth 42' of the lamination teeth. According to various aspects, a first diameter of the first through-hole 24 is smaller than a second diameter of the second through-hole 26, thereby providing a line-of-sight path for the sensor 34 to the rotor surface 22 and a line-of-sight path to the stator surface 32. According to various aspects, the first diameter of the first through-hole 24 can range from about 1.0 mm to about 1.5 mm.
[0034] Reference Figure 3 And refer again Figure 2 , a flow chart 48 shows the steps of using the apparatus and method 10 for measuring rotor temperature. After the start step 50, in the obtain step 52, a plurality of items are obtained from the vehicle sensor data. These data include the motor oil temperature T oil ; Infrared sensor stator temperature signal IR_stator_raw and infrared sensor rotor signal IR_stator_raw. Then obtain the object emissivity ε_obj of the rotor 14, determine the predetermined transmittance τ_atm, the atmospheric temperature T_atm and the temperature at the infrared sensor T_optic. Assume that the initial reflection sensing temperature T_refl_initial is equal to the motor oil temperature T of the motor 12 oil .
[0035] After obtaining step 52, if the motor oil temperature 54T oil If the initial reflected temperature 58T is less than 40°C, a plurality of independent temperature calibration steps may be performed. These steps include applying a temperature calibration range 1 having a temperature range of -30°C to 55°C in a first temperature calibration step 56. After the first temperature calibration step 56, if the initial reflected temperature 58T is less than 40°C, a plurality of independent temperature calibration steps may be performed. These steps include applying a temperature calibration range 1 having a temperature range of -30°C to 55°C in a first temperature calibration step 56. IR If the temperature is less than 40° C., the program proceeds to step 60 of applying the equation.
[0036] After the first temperature calibration step 56, if the initial reflected temperature 61T IR If the temperature is greater than or equal to 40°C, the program executes the second temperature calibration step 62. In the second temperature calibration step 62, since the temperature T IR is greater than or equal to 40°C, so the temperature calibration range 2 of 35°C to 150°C is applied. After the second temperature calibration step 62, if the initial reflected temperature T IR If the temperature is less than 140°C, the program jumps directly to step 60 of applying the equation.
[0037] After the first temperature calibration step 56, if the initial reflected temperature 66T IRIf the temperature is greater than or equal to 140°C, the program jumps to the third temperature calibration step 68. In the third temperature calibration step 68, since the temperature T IR Greater than or equal to 140° C., so the temperature calibration range 3 of 80° C. to 220° C. is applied. After the third temperature calibration step 68 , the program jumps directly to the equation application step 60 .
[0038] In the equation application step 60, the initial rotor temperature T_rotor_initial and the stator temperature T are obtained by applying the equation 1 defined below. stator .
[0039] In the parallel temperature calibration step, after obtaining step 52, if the oil temperature T oil 70 is greater than or equal to 40°C, then in the fourth temperature calibration step 72, the above-mentioned 35°C-150°C temperature calibration range 2 is applied. In the fourth temperature calibration step 72, if the initial reflected temperature 76T IR If the temperature is less than 140°C, the program jumps directly to step 60 of applying the equation.
[0040] After the fourth temperature calibration step 72, if the initial reflected temperature 76T IR If the initial reflected temperature 76T is greater than or equal to 140°C, the program jumps to the fifth temperature calibration step 78. In the fifth temperature calibration step 78, since the initial reflected temperature 76T IR Since the temperature is greater than or equal to 140° C., the temperature calibration range 3 of 80° C. to 220° C. mentioned above is applied. After the fifth temperature calibration step 78 , the program jumps directly to the equation application step 60 .
[0041] The rotor temperature measurement accuracy is improved by the rotor surface emission and reflection calibration without increasing the emissivity (e.g., if the rotor surface is painted). The rotor surface emission and reflection calibration applied in the equation application step 60 includes solving the following equation 1 to convert the rotor temperature (T rotor ) is determined as the reflected temperature T refl .
[0042] Equation 1:
[0043] W tot =(1-ε obj )·τ atm ·σ·(T refl ) 4 +ε obj ·τ atm ·σ·(T obj ) 4 +(1-τ atm )·σ·(T atm ) 4
[0044] In Equation 1 above, the total radiation W received by sensor 34 is tot = is equal to a number of terms including [emission of the surroundings reflected by the target defining at least the surface of the rotor] + [emission of the target] + [absorption of the atmosphere and external optics]. In Equation 1, ε obj is a predetermined emission rate based on the RPM of the rotor 14. In Equation 1, T atm is the predetermined transmittance.
[0045] After the equation application step 60, in the reflected temperature determination step 80, the reflected temperature T in the above equation 1 is determined by the following equation 2: refl :
[0046] Equation 2:
[0047] T refl =C refl x[(T rotor +T stator ) / 2]
[0048] The average transmission of the stator reflected by the rotor surface 22 through the first through-hole 24 is determined to formulate Equation 2. According to various aspects, the reflector constant C used in Equation 2 is refl According to other aspects, the reflector constant (C refl ) can be a value different from 0.85, which depends on the selected first through-hole diameter and the position of the first through-hole 24.
[0049] Continue to refer Figure 3 After the temperature reflection determination step 80 is completed, the program returns to the acquisition step 52 and the motor oil temperature T which was assumed to be equal to the motor 12 is set. oil The initial reflection sensing temperature T_refl_initial is replaced by T obtained in the temperature reflection determination step 80 using Equation 2. refl The calculated value of . Then at least the second iteration of the program using the flowchart 48 is completed. Then the second iteration completion signal 84 is generated, after which in the forwarding step 86 the rotor temperature T rotor and stator temperature T stator The value of is forwarded to the vehicle controller 88. The vehicle controller may include a motor heating model 90, a heat transfer model 92, and a coolant flow model 94, which collectively provide an input of the motor temperature 96 to the generator.
[0050] refer to Figure 4 And refer to it again Figures 1 to 3Verification 98 may be performed using the output signal of sensor 34 by comparing it to a signal that may be received from a second sensor 100, which may also be an infrared detector. A third aperture 102 may be formed in housing portion 104 that allows for temperature measurement of an outer surface 106 of rotor 14 for confirmation that the temperature measurement received by sensor 34 is consistent. Second sensor 100 may be used for confirmation purposes only or may be used as a redundant component with sensor 34.
[0051] Continue to refer Figure 4 And refer to it again Figure 1 An air gap 120 exists between the lens 114 of the sensor 134 and the housing 28 and rotor surface 22, and between the lens 114 of the sensor 134 and the stator surface 32. The air gap 120 minimizes heat transfer to the sensor 34, thereby providing non-contact mid-rotor temperature measurement using an infrared heat detector or sensor 34 in the air gap.
[0052] A stepped hole defined by first through-hole 24 and second through-hole 26 is formed in one of the plurality of stator laminations 38 to define an infrared radiation path to enable simultaneous infrared sensing on rotor surface 22 and stator surface 32. First through-hole 24 extends through stator lamination teeth 42 between stator windings 46.
[0053] The rotor temperature is measured on the rotor surface 22 in the air gap 120. Compared to known temperature estimation algorithms, the present rotor surface emission and reflection calibration method improves temperature measurement accuracy.
[0054] The disclosed apparatus and method 10 for measuring rotor temperature offer numerous advantages. They include a methodology that enables non-contact mid-rotor temperature measurement in the air gap using sensors such as infrared heat detectors. The methodology also includes rotor surface emission and reflection calibration methods to improve measurement accuracy. The methodology also includes a stepped hole created in the stator laminations that defines an infrared radiation path that enables simultaneous infrared sensing on both the rotor and stator surfaces. The through-hole extends through the stator lamination teeth between the copper windings. The rotor temperature measurement location is at the rotor surface in the air gap.
[0055] The description of the present disclosure is merely exemplary in nature, and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations should not be regarded as a departure from the spirit and scope of the present disclosure.
Claims
1. A device for measuring the temperature of a motor vehicle rotor, comprising: a motor having a rotor; a stator, the rotor being positioned within the stator, the stator having a stator surface; a first aperture or opening extending through the stator; a sensor positioned in alignment with the first aperture to sense a temperature of at least one surface of the rotor, the sensor having a lens; as well as an air gap between the lens of the sensor and the rotor, the air gap minimizing heat transfer from the rotor to the sensor and providing non-contact rotor temperature measurement in the air gap, and Wherein the air gap is arranged between the lens of the sensor and the stator surface.
2. The apparatus of claim 1, wherein the first aperture defines a stepped aperture extending through the stator.
3. The device of claim 2, further comprising a second aperture or opening extending through a housing supporting the sensor, wherein a diameter of the first aperture is smaller than a diameter of the second aperture.
4. The apparatus of claim 3, further comprising a stator surface visible to the sensor through the second aperture.
5. The apparatus of claim 1, wherein the air gap is further located between a housing supporting the sensor and a surface of the rotor.
6. The device of claim 1, wherein the stator comprises a plurality of teeth, the first aperture extending through at least one of the plurality of teeth.
7. The device of claim 1, wherein the sensor defines an infrared detector.