Energy-saving permanent magnet roller motor rotor magnetic steel temperature measuring device

Abstract

The invention relates to the technical field of temperature measuring devices, and discloses an energy-saving permanent magnet roller motor rotor magnetic steel temperature measuring device which comprises a motor rotating shaft and a motor winding fixed on the surface of the motor rotating shaft, a rotor is further arranged on the outer side of the motor winding, and magnetic steel and a temperature measuring assembly are fixedly installed on the inner wall of the rotor. The heat conduction probe is tightly attached to the surface of the magnetic steel, real-time temperature information of the magnetic steel can be obtained, and when the temperature of the magnetic steel changes, the temperature of the magnetic steel can be accurately detected through cooperation of the conduction rod made of the nickel-titanium memory alloy and the conversion plate formed by compounding two metal sheets with the large thermal expansion coefficient difference value. The conversion plate is bent and deformed due to different expansion amounts of the metal sheets on the two sides, the main reflection block and the auxiliary reflection block which are embedded in the free end of the conversion plate synchronously displace along with the conversion plate, then the displacement amount generated by the conversion plate is recorded by the laser displacement sensor, and the real-time temperature of the magnetic steel is reversely deduced according to the displacement amount. Dynamic real-time monitoring of magnetic steel temperature at different positions is realized.

Description

Technical Field

[0001] This invention relates to the field of temperature measuring device technology, and in particular to an energy-saving permanent magnet drum motor rotor magnet temperature measuring device. Background Technology

[0002] Currently, traditional electric drives only monitor the temperature of the motor stator windings. However, with the increase in motor power density and speed, as well as abnormal motor field weakening current, the motor rotor may experience abnormally high temperature rise, even exceeding the Curie temperature of the magnets. This can easily lead to irreversible demagnetization of the magnets. Therefore, monitoring the temperature of the motor rotor magnets is also crucial.

[0003] An existing patent (publication number: CN220022539U) discloses a temperature measuring structure for the rotor magnets of a permanent magnet motor and a permanent magnet motor. The permanent magnet motor includes a rotor and multiple magnets disposed on the outer peripheral wall of the rotor. There is a gap between any two magnets with a length along the rotor axis. The temperature measuring structure includes: an end cover disposed at the end of the rotor, the end cover having a through hole penetrating its inner and outer walls, and the distance from the through hole to the rotor axis is equal to the distance from the gap to the rotor axis; a temperature measuring guide rod, one end of which can pass through the through hole and extend to any position in any gap.

[0004] Although the distance from the through hole to the shaft is equal to the distance from the gap to the shaft, allowing the rotor to rotate and align the gaps at different positions with the through hole, thus enabling the temperature measuring rod to extend into the gaps at different positions for temperature measurement; and by adjusting the depth of the temperature measuring rod into the gap, the temperature measuring rod can measure the temperature at different axial positions of the magnet, resulting in more comprehensive temperature data, this application can only measure the temperature of the magnet after the motor has stopped rotating. It cannot achieve dynamic real-time monitoring, making it difficult to meet the need for continuous tracking of magnet temperature changes during motor operation. It suffers from monitoring lag, failing to detect temperature anomalies in a timely manner and providing early warnings, thus increasing the risk of magnet demagnetization due to overheating. Summary of the Invention

[0005] The purpose of this invention is to provide an energy-saving permanent magnet drum motor rotor magnet temperature measuring device to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an energy-saving permanent magnet drum motor rotor magnet temperature measuring device, comprising a motor shaft and a motor winding fixed on the surface of the motor shaft, a rotor is also provided on the outside of the motor winding, a magnet and a temperature measuring component are fixedly installed on the inner wall of the rotor, the temperature measuring component is used to monitor the temperature of the magnet, the temperature measuring component is evenly arranged at equal angles along the circumference of the rotor, and the temperature measuring component rotates synchronously with the rotor; The temperature measuring component includes a thermally conductive probe. An installation groove is provided at the contact point between the rotor and the magnet. The thermally conductive probe is embedded in the installation groove and is tightly attached to the surface of the magnet through thermally conductive silicone grease. A conduction rod is fixed to the other end of the thermally conductive probe, and a conversion plate is fixed to the other end of the conduction rod.

[0007] Preferably, the motor winding includes a first end cover, on which a mounting base is fixedly mounted. A laser displacement sensor is fixedly mounted inside the mounting base. A main reflector and a secondary reflector are embedded in the free end of the conversion plate, and the reflective surfaces of the main reflector and the secondary reflector both face the laser displacement sensor.

[0008] Preferably, the rotor includes a second end cover, the conversion plate passes through the second end cover, and counterweights are fixed on both sides of the conversion plate. The distance between the center of the counterweight and the rotation axis is equal to the free end rotation radius of the conversion plate. A placement groove is provided on the side of the second end cover, and the counterweight is engaged inside the placement groove. The conversion plate is made of two materials with a thermal expansion coefficient difference ≥15×10⁻⁶. -6 The plate is composed of metal sheets of different thicknesses at a temperature of 1:1.

[0009] Preferably, the heat-conducting probe is made of oxygen-free copper, and the surface of the heat-conducting probe is coated with an insulating high-temperature resistant ceramic coating. The conductive rod is made of nickel-titanium shape memory alloy. The conductive rod is used to conduct the heat conducted by the magnet to the heat-conducting probe to the conversion plate again, and at the same time, it can compensate for the deformation and vibration generated by the rotation of the rotor.

[0010] Preferably, both the main reflector and the sub-reflector are made of mirror stainless steel. The number of main reflectors is the same as the number of heat-conducting probes, and the reflection arc length of each main reflector is different. The sub-reflector is located on one side of the main reflector, and the number of sub-reflectors embedded on adjacent conversion plates increases sequentially.

[0011] Preferably, the laser displacement sensor is used to calculate the light transmission time window of each group of coded marker blocks based on the rotation speed and the angle interval of the measuring point, and to start sampling within the corresponding window to read the coding features and displacement of the marker blocks.

[0012] Preferably, a zero-position reference rod is fixed at any position on the side of the second end cap. The zero-position reference rod and the temperature measuring component are in the same plane. The zero-position reference rod is used to provide an initial phase reference for the laser displacement sensor.

[0013] Preferably, the thermal probe is interference-fitted with the mounting groove, and the end of the thermal probe away from the magnet is coaxially connected to the conductive rod. The connection between the conductive rod and the thermal probe and the conversion plate is fixed by welding, and the weld is coated with high-temperature resistant thermally conductive adhesive.

[0014] The technical effects and advantages of this invention are as follows: This invention utilizes a temperature-measuring component that rotates synchronously with the rotor's inner wall. By tightly adhering a thermally conductive probe to the surface of the magnet, real-time temperature information of the magnet can be obtained. Combined with a conductive rod made of nickel-titanium shape memory alloy and a conversion plate composed of two metal sheets with significantly different coefficients of thermal expansion, the conversion plate bends and deforms due to the different expansion amounts of the metal sheets on both sides when the magnet's temperature changes. The primary and secondary reflective blocks embedded at its free ends then shift synchronously. Subsequently, a laser displacement sensor records the displacement of the conversion plate and inversely derives the real-time temperature of the magnet based on the displacement, achieving dynamic real-time monitoring of the magnet's temperature at different locations. This solves the monitoring lag problem caused by the need to stop the machine for temperature measurement in traditional technologies and reduces the risk of magnet demagnetization due to overheating. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural schematic diagram of the temperature measuring device for the rotor magnet of the energy-saving permanent magnet drum motor of the present invention; Figure 2 This is a schematic diagram of the energy-saving permanent magnet drum motor rotor magnet temperature measuring device from another perspective. Figure 3 This is a front sectional view of the energy-saving permanent magnet drum motor rotor magnet temperature measuring device of the present invention. Figure 4 This invention relates to an energy-saving permanent magnet drum motor rotor magnet temperature measuring device. Figure 3 Enlarged view of point A in the middle; Figure 5 This invention relates to an energy-saving permanent magnet drum motor rotor magnet temperature measuring device. Figure 3 Enlarged view of point B in the middle; Figure 6 This is a schematic diagram of the temperature measuring component in the energy-saving permanent magnet drum motor rotor magnet temperature measuring device of the present invention.

[0016] In the diagram: 1. Motor shaft; 2. Motor windings; 201. First end cover; 202. Mounting bracket; 3. Rotor; 301. Second end cover; 302. Mounting slot; 4. Magnets; 5. Temperature measuring assembly; 501. Thermal probe; 502. Conducting rod; 503. Conversion plate; 504. Main reflector; 505. Secondary reflector; 506. Counterweight; 6. Laser displacement sensor; 7. Zero-position reference rod. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] This invention provides, for example Figures 1 to 6 The energy-saving permanent magnet drum motor rotor magnet temperature measuring device shown includes a motor shaft 1 and a motor winding 2 fixed on the surface of the motor shaft 1. A rotor 3 is also provided on the outside of the motor winding 2. Magnets 4 and a temperature measuring component 5 are fixedly installed on the inner wall of the rotor 3. The temperature measuring component 5 is used to monitor the temperature of the magnets 4. The temperature measuring component 5 is evenly arranged at equal angles along the circumference of the rotor 3. The temperature measuring component 5 rotates synchronously with the rotor 3. The synchronous rotation of the temperature measuring component 5 and the rotor 3 can avoid the interference of additional frictional heat with the temperature measuring accuracy. At the same time, the evenly arranged temperature measuring component 5 along the circumference of the rotor 3 can not only cover all the magnets 4, but also avoid affecting the dynamic balance of the rotor 3 during rotation, and reduce the impact of vibration on the temperature measuring structure.

[0019] Temperature measuring component 5 includes a thermal probe 501. A mounting groove 302 is provided at the contact point between rotor 3 and magnet 4. The thermal probe 501 is embedded inside the mounting groove 302 and tightly adhered to the surface of magnet 4 via thermal grease. A conduction rod 502 is fixed to the other end of the thermal probe 501, and a conversion plate 503 is fixed to the other end of the conduction rod 502. Motor winding 2 includes a first end cover 201, on which a mounting base 202 is fixed. A laser displacement sensor 6 is fixedly installed inside the mounting base 202. A main and secondary reverse winding is embedded at the free end of the conversion plate 503. The main reflector block 504 and the secondary reflector block 505, with their reflecting surfaces facing the laser displacement sensor 6, are included. The rotor 3 includes a second end cover 301, and a conversion plate 503 passes through the second end cover 301. Counterweights 506 are fixed to both sides of the conversion plate 503, and the distance between the center of the counterweight 506 and the rotation axis is equal to the free end rotation radius of the conversion plate 503. A placement groove is provided on the side of the second end cover 301, and the counterweights 506 are snapped into the placement groove. The conversion plate 503 is made of two materials with a thermal expansion coefficient difference ≥15×10⁻⁶. -6The conversion plate 503 is composed of two metal sheets with a thermal expansion coefficient difference of ≥15×10-6 / ℃, and the thickness of the two metal sheets is 1:1. When the motor is running, the rotor 3 drives the magnet 4 and the temperature measuring component 5 to rotate synchronously. The heat generated by the magnet 4 is quickly transferred to the heat-conducting probe 501 through the tightly attached thermal grease, and then conducted to the conversion plate 503 through the conduction rod 502. Since the conversion plate 503 is composed of two metal sheets with a thermal expansion coefficient difference of ≥15×10-6 / ℃ in a 1:1 thickness, the two metal sheets will expand to different degrees under the action of heat, which will cause the conversion plate 503 to bend and deform towards the side with a smaller thermal expansion coefficient, driving the main reflector block 504 and the sub-reflector block 505 embedded on it to move synchronously. At this time, the laser displacement sensor 6 records the displacement generated by the conversion plate 503 and inversely deduces the real-time temperature of the magnet 4 based on the displacement.

[0020] During this process, the counterweight 506 compensates for the centrifugal force pseudo-deformation at the free end of the conversion plate 503 through centrifugal force compensation. The compensation principle follows the centrifugal force torque balance formula: ; In the formula, m1 is the mass of the free end of the conversion plate 503, R1 is the rotation radius of the free end of the conversion plate 503, m2 is the total mass of the counterweight 506, R2 is the rotation radius of the counterweight 506, and w is the angular velocity of the rotor. This ensures that the displacement acquired by the laser is driven only by temperature changes, eliminating the interference of centrifugal force on the temperature measurement accuracy.

[0021] The heat-conducting probe 501 is made of oxygen-free copper and coated with an insulating high-temperature resistant ceramic coating. The conduction rod 502 is made of nickel-titanium shape memory alloy. The conduction rod 502 is used to conduct the heat from the magnet 4 to the heat-conducting probe 501 to the conversion plate 503. At the same time, it can compensate for the deformation and vibration caused by the rotation of the rotor 3. The oxygen-free copper heat-conducting probe 501 can quickly conduct the heat from the magnet 4, reduce heat loss, and ensure the timeliness of temperature conduction. Meanwhile, the insulating high-temperature resistant ceramic coating can isolate the electromagnetic interference inside the motor, prevent the heat-conducting probe 501 from becoming an electromagnetic conduction carrier, and avoid high temperature damage to the probe structure. In addition, the conduction rod 502 made of nickel-titanium shape memory alloy has both good thermal conductivity and elastic deformation capability, which can compensate for the radial runout and axial movement caused by the rotation of the rotor 3, ensuring that the heat-conducting probe 501 is always in close contact with the magnet 4, improving the continuity of heat conduction and the stability of the temperature measurement structure.

[0022] Both the main reflector block 504 and the sub-reflector block 505 are made of mirror stainless steel. The number of main reflector blocks 504 is the same as the number of heat-conducting probes 501, and the reflection arc length of each main reflector block 504 is different. The sub-reflector blocks 505 are set on one side of the main reflector blocks 504, and the number of sub-reflector blocks 505 embedded on adjacent conversion plates 503 increases sequentially. The different arc lengths of the main reflector blocks 504, combined with the increasing number of sub-reflector blocks 505, can solve the problem of measurement point overlap when the rotor 3 rotates at high speed. Specifically, when the laser displacement sensor 6 receives the reflected signal, it first identifies the corresponding temperature measuring component 5 number by recognizing the arc length characteristics of the main reflector block 504. The laser displacement sensor 6 distinguishes different temperature measuring components 5 by detecting the duration of the reflected signal, i.e., the rotation time corresponding to the arc length. At the same time, the laser displacement sensor 6 performs secondary encoding verification by counting the number of reflected pulses of the sub-reflector blocks 505 to further ensure the uniqueness and accuracy of the measurement point identification and avoid misjudgment caused by rotor 3 vibration or signal interference.

[0023] The laser displacement sensor 6 is used to calculate the light transmission time window for each group of coded marker blocks based on the rotation speed and the angular interval of the measuring point, and to start sampling within the corresponding window to read the coded features and displacement of the marker blocks. This avoids sampling the blank areas between marker blocks, reducing invalid data and missampling problems. The formula for calculating the light transmission time window is as follows: ; In the formula, t is the light transmission time window of a single measuring point, L is the arc length of the main reflector block 504, V is the linear velocity of the marker block rotation, R is the radius of rotation of the marker block, and n is the motor speed. The laser displacement sensor 6 synchronously reads the coded features and displacement, realizing the binding acquisition of measuring points and displacement, and providing a basis for temperature data attribution.

[0024] A zero-position reference rod 7 is fixed at any position on the side of the second end cover 301. The zero-position reference rod 7 and the temperature measuring component 5 are in the same plane. The zero-position reference rod 7 is used to provide an initial phase reference for the laser displacement sensor 6. The zero-position reference rod 7 provides a start trigger signal for the sampling cycle and triggers a cycle reset once every one rotation. Combined with the formula for the circumferential angle interval of the measuring point: ; In the formula, The circumferential angle interval between adjacent measuring points is N, and the number of measuring points is N. By establishing a mapping relationship between the rotation angle and the measuring points, the problem of rotor 3 rotation timing offset is solved. Even if the motor accelerates or decelerates, the sampling window can be corrected in real time through the zero-position reference to ensure that the sampling timing is aligned with the measuring point position.

[0025] The thermal probe 501 is interference-fitted with the mounting slot 302, and the end of the thermal probe 501 away from the magnet 4 is coaxially connected with the conduction rod 502. The connection between the conduction rod 502 and the thermal probe 501 and the conversion plate 503 is fixed by welding, and the weld is coated with high-temperature resistant thermally conductive adhesive. The interference fit of the mounting slot 302 of the thermal probe 501 can improve the connection stability between the thermal probe 501 and the mounting slot 302, and prevent the thermal probe 501 from loosening and shifting during high-speed rotation. At the same time, the connection between the conduction rod 502 and the thermal probe 501 and the conversion plate 503 is fixed by welding, and the weld is coated with high-temperature resistant thermally conductive adhesive. This not only improves the high-temperature resistance and stability of the connection position, but also prevents the weld from becoming a bottleneck for heat conduction, further improving the accuracy of temperature conduction and temperature measurement.

[0026] During use, when the magnets 4 heat up, the heat from each set of magnets 4 is transferred to the conduction rod 502 through the corresponding heat-conducting probe 501, and then conducted to the conversion plate 503 by the conduction rod 502. Since the conversion plate 503 is made of two materials with a thermal expansion coefficient difference ≥15×10⁻⁶, the heat is transferred to the magnets 4. -6 The converter plate 503 is composed of two metal sheets at a temperature of / ℃. Therefore, when the temperature of the converter plate 503 increases, the two metal sheets will bend and deform due to their different thermal expansion rates. The coded high-reflectivity marker block at its free end will generate a small radial / axial displacement. Subsequently, the laser displacement sensor 6 records the displacement generated by the converter plate 503 and deduces the real-time temperature of the magnet 4 based on the displacement. The temperature-displacement conversion follows the calibration formula below: ; In the formula, Δd is the displacement change of the free end of the conversion plate 503, K is the amplification factor of the conversion plate 503, ΔT is the temperature change, T is the real-time temperature of the magnet 4, and T0 is the ambient reference temperature. The magnification factor K can be derived based on the bimetallic sheet bending theory: ; In the formula, , respectively, are the coefficients of thermal expansion of the two metals, L is the length of the conversion plate 503, h is the total thickness of the conversion plate 503, and K is the mechanical structure additional amplification factor.

[0027] The laser displacement sensor 6 pre-calculates the light transmission time window of each group of main reflectors 504 and sub-reflectors 505 based on the motor speed and the angular interval of each temperature measuring component 5, and starts sampling within the corresponding window. At the same time, since the reflection arc lengths of the main reflectors 504 are different, the laser displacement sensor 6 can distinguish and determine the group of temperature measuring components 5 currently being sampled by identifying different reflection arc length codes. With the sub-reflectors 505 in increasing numbers, the position information of the temperature measuring components 5 is further confirmed, ensuring that the specific magnet 4 measuring point can be accurately matched when the rotor 3 is rotating at high speed. In addition, after detecting the zero-position reference rod 7 signal, the laser displacement sensor 6 performs a periodic reset, and then performs orderly sampling and data recording of each temperature measuring component 5 that passes by in sequence, thereby realizing real-time, multi-point monitoring of the temperature of the magnet 4 of the rotor 3.

[0028] During the rotation of the temperature measuring component 5, the counterweight 506 generates a reverse centrifugal force to counteract the pseudo-deformation of the free end of the conversion plate 503 caused by the rotation, so that the conversion plate 503 only deforms when the temperature changes, thus improving the accuracy of temperature measurement. At the same time, the transmission rod 502 is made of nickel-titanium shape memory alloy, which can not only efficiently conduct heat, but also compensate for the radial runout and axial movement generated during the rotation of the rotor 3, avoiding the relative position shift between the temperature measuring component 5 and the laser displacement sensor 6 due to mechanical vibration, and further improving the stability of displacement detection.

[0029] The present invention also provides a temperature measurement method, comprising the following steps: Step 1: Initialize the system and enter the number of measuring points N and the angle interval between adjacent measuring points. The correspondence between the 505 coding features of the main and secondary reflectors and the measurement points, the temperature-displacement calibration formula parameter K, and the environmental reference temperature T0 are determined to complete the algorithm parameter configuration. Step 2: Start the motor. The speed sensor collects the rotor speed n in real time. According to the rotation period formula... With angular velocity formula The rotation period and angular velocity of rotor 3 are calculated, and laser displacement sensor 6 enters standby sampling state. Step 3: When the zero-position reference rod 7 sweeps across the laser displacement sensor 6, the sensor detects the reference signal, triggers the cycle reset, and records the current time as t0, which is taken as the starting time point of this rotation cycle. Step 4: Based on the angle interval of the measuring points Given a rotation period T, calculate the theoretical arrival time t and the light transmission time window [t, t+t] of the i-th measuring point i=1,2,...,N. The formula for calculating the arrival time is: ; Step 5: When the system time reaches t, the laser displacement sensor 6 starts sampling, continuously collecting the reflection signals of the main and auxiliary reflection blocks 505 within t time, and forcibly shielding the signals outside the window to avoid invalid sampling and mis-sampling; Step 6: Extract the features of the collected reflection signals, identify the arc length feature of the main reflection block 504 and the quantity feature of the auxiliary reflection block 505, and match the corresponding measurement points; if the coding feature cannot match the preset information, it is determined as invalid data, discarded, and wait for the next measurement point sampling window; Step 7: Perform mean filtering on the sampling data within the window to eliminate the laser sampling noise, and obtain the displacement change amount Δd of the conversion board 503 corresponding to the i-th measurement point; Step 8: Substitute into the temperature-displacement calibration formula and the error correction formula , and calculate the true temperature T of the magnetic steel 4 at the i-th measurement point; Step 9: Bind and store the three information of the measurement point - T - acquisition time, and at the same time output the temperature data to the control system; Step 10: If i = N, it means that the full measurement point sampling of a rotation cycle is completed, wait for the signal trigger of the next zero reference rod 7, and repeat steps 3 - 9; if i < N, jump to step 4, calculate the sampling window parameters of the next measurement point, and continue sampling; Step 11: Real-time judge whether the temperature T of each measurement point exceeds the preset warning threshold. If it exceeds, trigger an alarm signal, record the abnormal data and the measurement point position, and conduct fault troubleshooting and handling.

[0030] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An energy-saving permanent magnet drum motor rotor magnet temperature measuring device, comprising a motor shaft (1) and a motor winding (2) fixed on the surface of the motor shaft (1), wherein a rotor (3) is also provided on the outside of the motor winding (2), characterized in that: The inner wall of the rotor (3) is fixedly installed with a magnet (4) and a temperature measuring component (5). The temperature measuring component (5) is used to monitor the temperature of the magnet (4). The temperature measuring component (5) is evenly arranged at equal angles along the circumference of the rotor (3). The temperature measuring component (5) rotates synchronously with the rotor (3). The temperature measuring component (5) includes a thermal probe (501). An installation groove (302) is provided at the contact point between the rotor (3) and the magnet (4). The thermal probe (501) is embedded in the installation groove (302) and is tightly attached to the surface of the magnet (4) through thermal grease. A conduction rod (502) is fixed at the other end of the thermal probe (501), and a conversion plate (503) is fixed at the other end of the conduction rod (502).

2. The energy-saving permanent magnet drum motor rotor magnet temperature measuring device according to claim 1, characterized in that: The motor winding (2) includes a first end cover (201), on which a mounting base (202) is fixed. A laser displacement sensor (6) is fixedly installed inside the mounting base (202). A main reflector (504) and a secondary reflector (505) are embedded at the free end of the conversion plate (503). The reflective surfaces of the main reflector (504) and the secondary reflector (505) are both facing the laser displacement sensor (6).

3. The energy-saving permanent magnet drum motor rotor magnet temperature measuring device according to claim 1, characterized in that: The rotor (3) includes a second end cover (301), and the conversion plate (503) passes through the second end cover (301). Counterweights (506) are fixed on both sides of the conversion plate (503), and the distance between the center of the counterweight (506) and the rotation axis is equal to the free end rotation radius of the conversion plate (503). A placement groove is provided on the side of the second end cover (301), and the counterweights (506) are snapped into the placement groove. The conversion plate (503) is made of two materials with a thermal expansion coefficient difference ≥15×10⁻⁶. -6 The plate (503) is composed of metal sheets of different thicknesses at a temperature of 1:

1.

4. The energy-saving permanent magnet drum motor rotor magnet temperature measuring device according to claim 1, characterized in that: The heat-conducting probe (501) is made of oxygen-free copper. The surface of the heat-conducting probe (501) is coated with an insulating high-temperature resistant ceramic coating. The conductive rod (502) is made of nickel-titanium shape memory alloy. The conductive rod (502) is used to conduct the heat from the magnet (4) to the heat-conducting probe (501) to the conversion plate (503) again, and at the same time, it can compensate for the deformation and vibration caused by the rotation of the rotor (3).

5. The energy-saving permanent magnet drum motor rotor magnet temperature measuring device according to claim 2, characterized in that: Both the main reflector (504) and the sub-reflector (505) are made of mirror stainless steel. The number of the main reflector (504) is the same as the number of the heat-conducting probes (501), and the reflection arc length of each main reflector (504) is different. The sub-reflector (505) is located on one side of the main reflector (504), and the number of sub-reflectors (505) embedded on adjacent conversion plates (503) increases sequentially.

6. The energy-saving permanent magnet drum motor rotor magnet temperature measuring device according to claim 2, characterized in that: The laser displacement sensor (6) is used to calculate the light transmission time window of each group of coded marker blocks according to the rotation speed and the angle interval of the measuring point, and to start sampling within the corresponding window to read the coding features and displacement of the marker blocks.

7. The energy-saving permanent magnet drum motor rotor magnet temperature measuring device according to claim 3, characterized in that: A zero-position reference rod (7) is fixed at any position on the side of the second end cap (301). The zero-position reference rod (7) and the temperature measuring component (5) are in the same plane. The zero-position reference rod (7) is used to provide an initial phase reference for the laser displacement sensor (6).

8. The energy-saving permanent magnet drum motor rotor magnet temperature measuring device according to claim 1, characterized in that: The thermal probe (501) is interference-fitted with the mounting groove (302), and the end of the thermal probe (501) away from the magnet (4) is coaxially connected with the conductive rod (502). The connection between the conductive rod (502) and the thermal probe (501) and the conversion plate (503) is fixed by welding, and the weld is coated with high-temperature resistant thermally conductive adhesive.

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