A permanent magnet motor temperature rise suppression device and system using a phase change material package

Abstract

The application provides a permanent magnet motor temperature rise suppression device and system adopting a phase change material package, and relates to the technical field of permanent magnet motors. The device comprises a permanent magnet motor body, a heat conduction plate and a mounting shell, a sealed cavity is formed between the two, and the cavity is filled with a three-dimensional graphene aerogel shaped composite phase change material. The heat conduction plate is provided with a curved cooling pipe, the outer wall of the cooling pipe is provided with a bionic high-thermal-conductivity micro-rib array, the array penetrates through the aerogel directional pores and is embedded in the phase change material matrix to form a synergistic channel of water cooling active heat dissipation and phase change latent heat passive absorption. A model prediction control algorithm based on liquid phase rate dynamic observation is built in the control system, a liquid phase rate observer is constructed by collecting motor parameters in real time, a cooling flow increment is output in advance before the latent heat is exhausted, and feedforward scheduling is realized. The application improves the problems of easy leakage, poor heat conduction and control lag of the phase change material, reduces the risk of temperature mutation and the number of invalid start and stop of the water pump, and improves the stability and service life of the motor.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor technology, and specifically to a permanent magnet motor temperature rise suppression device and system using phase change material encapsulation. Background Technology

[0002] Permanent magnet motors, with their outstanding advantages such as small size, low loss, high efficiency, and high power density, have been widely used in many fields, including medical devices, new energy vehicles, and aerospace. However, during long-term high-load operation, armature losses, iron losses, and mechanical losses accumulate, generating a large amount of heat. If heat dissipation is not timely, the internal temperature of the motor can easily rise above 80°C, exceeding the critical demagnetization temperature of high-performance permanent magnet materials such as neodymium iron boron (NdFeB). This leads to irreversible demagnetization of the permanent magnets, resulting in decreased motor torque, reduced efficiency, or even complete motor failure. Therefore, effective temperature rise suppression technology is of great significance for ensuring the operational reliability and service life of permanent magnet motors.

[0003] Currently, heat dissipation solutions for permanent magnet motors mainly include air cooling, water cooling, and heat sink fins. Traditional air cooling has low efficiency and cannot meet the heat dissipation requirements of high power density motors; conventional water cooling systems have short heat exchange paths and significant control lag, with cooling water often only starting to circulate after the motor surface temperature has risen, making it impossible to intervene in the temperature rise process in advance; straight cooling pipes have short heat exchange paths and small contact areas, resulting in insufficient heat exchange; and single heat sink fins are prone to heat dissipation bottlenecks under high-temperature conditions.

[0004] To address these issues, existing research has attempted to introduce phase change materials (PCMs) into motor cooling systems, utilizing their latent heat storage properties to buffer against sudden high-temperature shocks. However, current PCM application schemes suffer from three major drawbacks: First, solid-liquid PCMs expand in volume and exhibit high fluidity after liquefaction, making them prone to leakage using traditional encapsulation methods. This leads to PCM loss and contamination of the motor's internal structure. Second, conventional PCMs such as paraffin have extremely low thermal conductivity, approximately 0.25 W / m·K, resulting in very slow heat transfer within them. This creates an "insulation layer" between the motor and cooling structure, hindering heat dissipation and exacerbating the heat buildup effect. Third, existing water-cooling systems often employ PID control strategies, passively adjusting based solely on real-time feedback of the motor's surface temperature. They cannot detect the latent heat consumption state within the PCM. When the liquid phase fraction of the PCM approaches 1 and the latent heat is nearly exhausted, the control strategy lacks effective internal state observations to intervene in advance, causing a sudden loss of control over the motor temperature within a short period.

[0005] Furthermore, while existing model predictive control schemes have incorporated predictive mechanisms, their controlled variable remains the motor surface temperature. This makes it difficult to fully reflect the unobservable internal state of the phase change material, and they lack a synergistic optimization mechanism between water-cooled active heat dissipation and passive phase change heat storage. Meanwhile, the mechanical vibrations generated during permanent magnet motor operation not only affect the motor's own stability but also transmit to related equipment. Existing vibration damping structures are mostly single-spring structures with limited damping effects, and are often designed independently from the heat dissipation structure. Some damping components even obstruct heat dissipation channels, indirectly exacerbating the temperature rise problem.

[0006] In view of the above, this application is hereby submitted. Summary of the Invention

[0007] The present invention provides a permanent magnet motor temperature rise suppression device and system using phase change material encapsulation, which can at least partially improve the above-mentioned problems.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A permanent magnet motor temperature rise suppression device using phase change material encapsulation includes: a permanent magnet motor body, thermally conductive silicone grease, a heat-conducting plate, a curved cooling pipe, and a mounting shell. The mounting shell covers the outer wall of the permanent magnet motor body, enclosing the front end face and the outer periphery of the side wall of the permanent magnet motor body, forming a sealed cavity that penetrates the front end region and the side wall region of the permanent magnet motor body. The thermally conductive silicone grease is applied to the front end face of the permanent magnet motor body, and the heat-conducting plate is embedded in the front end region of the sealed cavity. The heat-conducting plate conducts heat... The silicone grease is tightly attached to the front end face of the permanent magnet motor body. The sealed cavity is filled with a shaped composite phase change material. An installation groove is provided through the inside of the heat-conducting plate. A curved cooling pipe is installed inside the installation groove. A biomimetic high thermal conductivity micro-rib array is arranged in an alternating manner on the outer wall of the curved cooling pipe. The biomimetic high thermal conductivity micro-rib array penetrates the directional pores of the support skeleton of the shaped composite phase change material and is embedded in the matrix of the shaped composite phase change material, forming a synergistic temperature rise suppression pathway of water-cooled active heat dissipation and passive absorption of latent heat of phase change. The shaped composite phase change material is used to absorb and store the heat generated by the permanent magnet motor body, and the curved cooling pipe is used to circulate the cooling medium and dissipate the heat from the heat-conducting plate and the sealed cavity.

[0010] The present invention also provides a permanent magnet motor temperature rise suppression system encapsulated with phase change material, which includes: a temperature sensor, a flow control valve, a variable frequency water pump, an edge computing controller, and a permanent magnet motor temperature rise suppression device encapsulated with phase change material as described above, all of which are uniformly distributed along the axial direction in a sealed cavity. The edge computing controller is configured to perform the following steps by executing a model predictive control algorithm based on dynamic observation of the phase ratio of a phase change liquid, which is stored internally: Real-time acquisition of collected data, including the operating current, speed, surface temperature of the permanent magnet motor body, and the temperature difference between the inlet and outlet water of the curved cooling pipe; Based on the collected data, and according to the preset phase change material liquid phase rate dynamic observer, combined with the equivalent thermal conductivity model of three-dimensional graphene aerogel, the real-time liquid phase rate of the phase change material in the sealed cavity is calculated. Based on the real-time liquid phase ratio and motor heat generation power prediction model, before the real-time liquid phase ratio reaches the preset depletion threshold, the optimal cooling water flow increment is solved through the cost function, and the control command is output to the variable frequency water pump in advance to realize feedforward cooling scheduling.

[0011] In summary, this device includes a permanent magnet motor body, a heat-conducting plate, a shock-absorbing structure, and a phase change encapsulation sealed cavity. The sealed cavity is filled with a composite phase change material encapsulated in three-dimensional graphene aerogel, and the outer wall array of the built-in curved cooling pipe features a biomimetic high thermal conductivity microrib array. The microrib array penetrates the pores of the aerogel, forming a synergistic heat-conducting bridge. Furthermore, this system is equipped with an edge computing controller and incorporates a Model Predictive Control (MPC) algorithm based on dynamic observation of the phase change liquid fraction. This invention overcomes the limitations of traditional motor cooling systems that prioritize structure over algorithm. Compared to existing technologies that passively adjust water volume based solely on surface temperature, this algorithm gives the control system the ability to "see through" the internal melting state of the phase change material. By introducing a liquid fraction exponential penalty term into the objective function, the system can perform "pre-cooling and heat extraction" before the latent heat of the phase change is exhausted, through the biomimetic microribs and aerogel network. This not only helps reduce the risk of temperature surges in the later stages of motor overload, greatly improving the operational stability and service life of permanent magnet motors, but also reduces the number of ineffective start-stop cycles of variable frequency water pumps, achieving deep synergistic optimization of thermodynamics and control dynamics. Attached Figure Description

[0012] Figure 1 This is a front view of the permanent magnet motor temperature rise suppression device encapsulated with phase change material provided in the first embodiment of the present invention.

[0013] Figure 2 This is a front view schematic diagram of the permanent magnet motor temperature rise suppression device encapsulated with phase change material provided in the first embodiment of the present invention.

[0014] Figure 3 This is a side view of the temperature rise suppression device for a permanent magnet motor encapsulated with phase change material provided in the first embodiment of the present invention.

[0015] Figure 4This is a partial structural schematic diagram of a permanent magnet motor temperature rise suppression device encapsulated with phase change material provided in the first embodiment of the present invention.

[0016] Figure 5 This is a partially enlarged structural schematic diagram of the permanent magnet motor temperature rise suppression device encapsulated with phase change material provided in the first embodiment of the present invention.

[0017] Figure 6 This is a schematic diagram of the sealed cavity structure of the permanent magnet motor temperature rise suppression device encapsulated with phase change material provided in the first embodiment of the present invention.

[0018] Figure 7 This is a schematic diagram illustrating the synergistic heat transfer relationship between the biomimetic high thermal conductivity microrib array on the outer wall of the curved cooling pipe and the three-dimensional graphene aerogel-shaped phase change material provided in the first embodiment of the present invention.

[0019] Figure 8 This is a comparison curve of motor temperature rise provided in an embodiment of the present invention.

[0020] Figure 9 This is an MPC control program flowchart of a permanent magnet motor temperature rise suppression system using phase change material encapsulation provided in the second embodiment of the present invention.

[0021] Figure 10 This is a schematic diagram of the liquid phase fraction of the phase change material in the permanent magnet motor temperature rise suppression system encapsulated with phase change material, provided in the second embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] refer to Figures 1 to 5As shown, the first embodiment of the present invention discloses a permanent magnet motor temperature rise suppression device encapsulated with phase change material, which includes: a permanent magnet motor body 1, thermally conductive silicone grease 2, a heat-conducting plate 3, a curved cooling pipe 5, and a mounting shell 19. The mounting shell 19 covers the outer wall of the permanent magnet motor body 1, enclosing the front end face and the outer periphery of the side wall of the permanent magnet motor body 1, forming a sealed cavity with the permanent magnet motor body 1 that penetrates the front end region and the side wall region. The thermally conductive silicone grease 2 is applied to the front end face of the permanent magnet motor body 1, and the heat-conducting plate 3 is embedded in the front end region of the sealed cavity. Within the domain, the heat-conducting plate 3 is tightly attached to the front end face of the permanent magnet motor body 1 through the thermal grease 2. The sealed cavity is filled with a shaped composite phase change material. An installation groove 4 is provided through the interior of the heat-conducting plate 3. A curved cooling pipe 5 is installed inside the installation groove 4. A biomimetic high thermal conductivity micro-rib array is provided on the outer wall of the curved cooling pipe 5 in an alternating manner. The biomimetic high thermal conductivity micro-rib array penetrates the directional pores of the support skeleton of the shaped composite phase change material and is embedded in the matrix of the shaped composite phase change material, forming a synergistic temperature rise suppression pathway of water-cooled active heat dissipation and passive absorption of latent heat of phase change. The shaped composite phase change material is used to absorb and store the heat generated by the permanent magnet motor body 1, and the curved cooling pipe 5 is used to circulate the cooling medium and discharge the heat from the heat-conducting plate 3 and the sealed cavity.

[0024] The shaped composite phase change material occupies 80-90% of the sealed cavity volume, leaving space for volume expansion. The shaped composite phase change material is a three-dimensional graphene aerogel-encapsulated composite phase change material, comprising a matrix and a supporting framework. The matrix is ​​solidified in the supporting framework via vacuum impregnation. The matrix is ​​a core material composed of paraffin wax and octadecanoic acid in a 3:1 ratio, with a phase change temperature of 45-60℃ and a latent heat of phase change ≥200J / g. The supporting framework is a three-dimensional graphene aerogel with a multi-level porous structure, an equivalent thermal conductivity ≥2.85W / (m·K), and a leakage rate <0.5%. It should be noted that the shaped composite phase change material can be replaced with a tin-bismuth alloy (65% tin + 35% bismuth, phase change temperature 50-55℃, latent heat of phase change ≥180J / g) or a polyvinyl alcohol-epoxy resin composite phase change material.

[0025] It also includes an outlet connector 8, an outlet pipe 9, an inlet connector 6, and an inlet pipe 7. The outlet connector 8 is located at the first end of the curved cooling pipe 5. The first end of the curved cooling pipe 5 is connected to the outlet pipe 9 through the outlet connector 8. The second end of the curved cooling pipe 5 is connected to the inlet connector 6 via a G1 / 2 thread. A fluororubber sealing ring (Shore hardness 70-80HA) is provided at this connection. The second end of the curved cooling pipe 5 is connected to the inlet pipe 7 through the inlet connector 6. The inlet pipe 7 is a nylon reinforced hose with an inner diameter of 8-12mm and a pressure resistance rating of ≥1.0MPa. The inlet pipe 7 is wrapped with insulation cotton (5-8mm thick).

[0026] The curved cooling pipe 5 is arranged in a continuous S-shape and is made of stainless steel or copper (pipe diameter 6-10mm, pipe wall thickness 1-1.5mm). The total length of the curved cooling pipe 5 is 3-5 times that of the heat conduction plate 3. The cooling medium flowing inside the pipe is cooling water or 5% ethylene glycol aqueous solution (flow rate 6L / min).

[0027] The heat-conducting plate 3 has multiple sets of heat dissipation fins 10 at its top and bottom, and the heat dissipation fins 10 are located in front of the permanent magnet motor body 1. Each heat dissipation fin 10 has a micro-pit with a diameter of 1-2 mm and a depth of 0.5 mm on its surface. The heat dissipation fins 10 are made of aluminum-magnesium alloy, with a single fin thickness of 1-1.5 mm and a spacing of 3-5 mm. Each set of heat dissipation fins 10 has 15-25 fins, and they are integrally extruded or welded to the heat-conducting plate 3. The heat-conducting plate 3 is made of 6061 aluminum alloy or copper, with a thickness of 8-12 mm and a surface roughness Ra≤0.8μm.

[0028] Specifically, in this embodiment, the heat of the permanent magnet motor body 1 is conducted to the heat-conducting plate 3 by the coated thermal grease 2, and the cooling water is introduced into the curved cooling pipe 5 through the water inlet pipe 7 and then discharged through the water outlet pipe 9 to complete the water cooling cycle. With the setting of the heat-conducting plate 3, the permanent magnet motor body 1 is protected by heat dissipation through water cooling. The heat is further dissipated by the installed heat dissipation fins 10, thereby preventing the motor from getting too hot and playing a temperature protection role to ensure the normal operation of the permanent magnet motor and effectively solving the problems and deficiencies in existing motors.

[0029] Please see Figure 6 , Figure 7The spatial layout of the sealed cavity of this device is as follows: the mounting shell 19 simultaneously covers the front end face and the outer periphery of the side wall of the permanent magnet motor body 1. The front heat dissipation module composed of thermally conductive silicone grease 2 and heat-conducting plate 3 is embedded in the front end area of ​​the sealed cavity. The back of the heat-conducting plate 3 is tightly bonded to the front end face of the motor through the thermally conductive silicone grease 2. The front of the heat-conducting plate 3 (away from the motor side) is water-cooled through the curved cooling pipe 5 embedded in the mounting groove 4. The biomimetic high thermal conductivity microrib array extends radially outward from the outer wall of the cooling pipe, penetrates the side area of ​​the heat-conducting plate 3, and penetrates into the three-dimensional graphene aerogel shaped phase change material layer in the sealed cavity, thereby realizing the direct thermal connection between the water cooling pipe and the phase change material, solving the problem of the heat dissipation module and the heat storage module being independent of each other and having superimposed thermal resistance. The sealed cavity of this device is not simply filled with ordinary phase change material. This invention uses a vacuum impregnation method to prepare shaped phase change material. First, a three-dimensional graphene aerogel with a directional microporous structure is prepared by directional freeze-drying and high-temperature reduction of graphene oxide aqueous solution. Subsequently, paraffin wax and octadecanoic acid (mixed in a 3:1 ratio) are melted and adsorbed into micropores using the capillary force of aerogel under a vacuum below 100 Pa. The micropores of the aerogel firmly lock the liquid paraffin / octadecanoic acid in place through capillary surface tension. Even when the motor temperature reaches above 80°C (exceeding the phase change temperature of 45-60°C), and the phase change material changes from solid to liquid, no macroscopic leakage occurs. This improves upon the problems of traditional encapsulation, which is prone to leakage and requires a large amount of expansion space.

[0030] Meanwhile, the outer wall of the curved cooling pipe 5 features a biomimetic high thermal conductivity microrib array arranged in an alternating pattern. The microrib array is precision milled from OFHC copper (thermal conductivity 400 W / (m·K)) and has a cylindrical needle-fin structure. The needle fins have a diameter of 1.5~2.0 mm, a height of 8~12 mm, a lateral spacing of 3~4 mm, and a longitudinal spacing of 2~3 mm. Adjacent needle fin rows are arranged in an alternating pattern to enhance turbulence. The needle fin roots are vacuum brazed to the outer wall of the cooling pipe using BCu-1 type copper-based brazing filler metal. The weld tensile strength is ≥200 MPa, reliably withstanding motor vibration conditions. The needle-fin surface is precision-machined to a roughness Ra of 1.6~3.2µm, significantly enhancing the interfacial bonding strength with the three-dimensional graphene aerogel network. Each needle-fin's axis extends outward perpendicular to the cooling tube axis, penetrating the directional pores of the aerogel and embedding into the paraffin / octadecanoic acid composite phase change material matrix. This forms a highly efficient synergistic heat transfer pathway: "water-cooled low-temperature end → copper needle-fin solid-phase heat conduction → graphene framework network → phase change material heat storage," effectively eliminating heat spot accumulation within the phase change material and increasing the overall equivalent thermal conductivity of the composite material to over 2.85 W / (m·K). When the motor experiences a sudden overload, the phase change material absorbs latent heat for buffering; when rapid latent heat reset is required, cooling water actively extracts heat from the aerogel network through the micro-fin array, accelerating the solidification of the phase change material.

[0031] The "biomimetic" design of the aforementioned biomimetic high thermal conductivity microrib array is inspired by the fractal diffusion layout of plant roots: plant roots branch out from the main root to the hair roots, maximizing the contact area with the soil through the optimal topological path; similarly, this invention arranges OFHC copper cylindrical needles in an alternating array in a three-dimensional graphene aerogel porous matrix to simulate the multi-level interface contact mechanism of "roots penetrating pores", maximizing the solid-phase contact area between the copper fins and the aerogel skeleton. The performance comparison with other arrangements is as follows (based on COMSOL finite element thermal flow field simulation, 7.5kW motor, rated operating conditions): ① Uniform arrangement (equal spacing, non-staggered): The copper-aerogel contact area is 100% of the baseline value, the average interface thermal resistance is 0.025cm²·K / W, and the probability of hot spots is 100%; ② Random distribution: The copper-aerogel contact area is about 95%, the probability of hot spots is about 78%, and the heat transfer uniformity is poor; ③ The staggered array of this invention (imitating plant roots): The copper-aerogel contact area is increased to about 135% (35% higher than uniform arrangement), the average interface thermal resistance is reduced to 0.018cm²·K / W, the probability of hot spots is reduced to about 40% (60% lower than uniform arrangement), and the maximum temperature difference within the PCM layer is reduced from 11.2℃ to 4.8℃, verifying the superiority of the staggered arrangement.

[0032] Preferably, in this embodiment, a fixing seat 11 is provided at each of the four bottom corners of the permanent magnet motor body 1, and a support column 12 is fixedly connected to the bottom of each fixing seat 11. A guide slider 13 is provided at the bottom end of each support column 12. The fixing seat 11 and the permanent magnet motor body 1 are detachably connected by M8-M10 bolts. The support column 12, the fixing seat 11, and the guide slider 13 are all fixed by argon arc welding. The support column 12 is made of Q235 steel with a diameter of 15-20mm and a length of 30-40mm.

[0033] The guide slider 13 is slidably connected to a shock absorber 14 on its surface. A mounting plate 15 is fixedly connected to the bottom end of each shock absorber 14. Mounting holes 17 are equidistantly arranged through the top of the mounting plate 15. The outer wall of the guide slider 13 and the inner wall of the shock absorber 14 are in clearance fit (0.1-0.3mm). The guide slider 13 is made of 45# steel, with a hard chrome plating thickness of 0.05-0.1mm. The shock absorber 14 has an inner diameter of 25-30mm. The shock absorber 14 is made of seamless steel pipe with a length of 40-50 mm. Multiple sets of springs 16 are installed equidistantly inside the shock absorber 14. One end of each spring 16 is fixedly connected to the bottom of the guide slider 13. The spring 16 is a cylindrical helical compression spring (material 60Si2Mn, elastic coefficient 20-30N / mm, free height 20-25mm). There are 3-5 springs 16 in each set of shock absorber 14. The springs 16 are welded to the guide slider 13 and the shock absorber 14.

[0034] Multiple sets of reinforcing ribs 18 are equidistantly arranged on the outer wall of the permanent magnet motor body 1. One side surface of the reinforcing rib 18 is fixedly connected to the mounting shell 19. The reinforcing rib 18 is made of 6061 aluminum alloy with a thickness of 3-5mm and an adjacent spacing of 15-20mm. The reinforcing rib 18, permanent magnet motor body 1, and mounting shell 19 are all welded together. The mounting shell 19 is made of cold-rolled steel plate with a thickness of 2-3mm. The surface of the cold-rolled steel plate is sprayed with a high-temperature resistant and anti-corrosion coating with a thickness of 0.1-0.2mm.

[0035] The thermal conductivity of the thermal grease 2 is ≥1.5W / (m). The biomimetic high thermal conductivity microrib array is made of OFHC copper, precision milled, and has a thermal conductivity ≥400W / (m²). The thickness is 0.5-1mm. The structure consists of a cylindrical needle-fin array with a diameter of 1.5~2.0mm, a height of 8~12mm, a lateral spacing of 3~4mm, and a longitudinal spacing of 2~3mm. Adjacent rows of needles are staggered (the misalignment is half the lateral spacing) to enhance the turbulence between the outer wall of the cooling tube and the phase change material. The root of the needle and the outer wall of the curved cooling tube 5 are bonded together in a vacuum brazing furnace using BCu-1 type copper-based brazing filler metal (furnace temperature 880~920℃, holding time 10~15min). The weld tensile strength is ≥200MPa, which can reliably withstand the full-load vibration of the motor (amplitude ≤2mm, frequency ≤100Hz). The surface of the needle is precision machined to a surface roughness Ra1.6~3.2µm to enhance the interfacial thermal contact with the pore walls of the three-dimensional graphene aerogel and reduce the interfacial thermal resistance to ≤0.02cm²·K / W.

[0036] In this embodiment, the device supports the entire permanent magnet motor through multiple sets of support columns 12. The shock absorption structure composed of shock absorber cylinder 14, guide slider 13, spring 16 and mounting plate 15 can buffer and reduce the vibration generated during motor operation. When the motor is running, the elastic deformation of spring 16 absorbs the vibration potential energy, which not only protects the motor, but also prevents high-frequency vibration from damaging the internal phase change material sealing micropore structure.

[0037] Specifically, during the operation of this permanent magnet motor, armature losses, iron losses, and mechanical losses continuously generate heat, which initially accumulates on the surface of the motor body. Due to the microscopic gaps between the permanent magnet motor body 1 and the heat-conducting plate 3, air within these gaps hinders heat transfer. The thermal grease 2 applied between them has excellent thermal conductivity, effectively filling these gaps, eliminating the air insulation layer, and forming a continuous heat conduction path. This allows the heat from the surface of the permanent magnet motor body 1 to be quickly and evenly conducted to the heat-conducting plate 3. The heat-conducting plate 3, acting as an intermediate heat transfer carrier, further conducts the absorbed heat to the curved cooling pipe 5 embedded in its internal mounting groove 4. Cooling water is introduced into the curved cooling pipe 5 through the water inlet pipe 7. As the cooling water flows within the curved pipe, it comes into full contact with the inner wall of the pipe, absorbing the heat transferred by the pipe through heat exchange, thus raising the temperature of the cooling water. Compared to straight pipes, the curved structure design extends the flow path and residence time of cooling water within the pipe, improving heat exchange efficiency. After absorbing heat, the cooling water is discharged through the outlet connector 8 and the outlet pipe 9, completing one water cooling cycle.

[0038] Through continuous water cooling circulation, a large amount of heat generated by the motor can be stably removed, achieving core cooling. The remaining heat on the heat-conducting plate 3 that is not completely removed by water cooling is transferred to the multiple sets of heat dissipation fins 10 on its top and bottom. The heat dissipation fins 10 are made of high thermal conductivity material and are densely distributed, greatly increasing the contact area with the air. After the heat is conducted to the surface through the heat dissipation fins 10, a temperature difference is formed with the surrounding air, and the heat is dissipated into the air through natural convection, effectively supplementing the water cooling heat dissipation and further reducing the temperature of the heat-conducting plate 3. This ensures that the temperature of the permanent magnet motor body 1 is always controlled within a safe range. The outer wall of the permanent magnet motor body 1 is fixed to the mounting shell 19 by the reinforcing ribs 18, forming a sealed cavity between the mounting shell 19 and the motor body. The phase change material filled in the cavity can play a role in energy storage and regulation. When the motor temperature rises, the phase change material absorbs heat and undergoes a phase change (solid to liquid), storing a large amount of latent heat to prevent the motor temperature from soaring. When the motor load decreases or stops running, the phase change material releases the stored latent heat (liquid to solid), maintaining a slow decrease in motor temperature and preventing damage to motor components due to sudden temperature drops. At the same time, in conjunction with water cooling and finned heat dissipation, a dynamic temperature balance is achieved.

[0039] The vibration generated by the permanent magnet motor body 1 during operation is transmitted to the support column 12 through the fixed seats 11 at its four bottom corners. The support column 12, as a connecting component, further transmits the vibration to the guide slider 13 at its bottom end. The guide slider 13 is slidably connected inside the shock absorber 14. When the vibration is transmitted to the guide slider 13, the guide slider 13 will move up and down inside the shock absorber 14, compressing or stretching the multiple sets of springs 16 installed at equal intervals inside the shock absorber 14. The springs 16 have good elastic deformation capability. When compressed or stretched, they will convert the kinetic energy generated by the vibration into the elastic potential energy of the springs 16, thereby consuming the vibration energy and achieving initial buffering of the vibration. The sliding fit structure between the guide slider 13 and the shock absorber 14 can limit the displacement direction of the guide slider 13, prevent it from shifting laterally, and ensure the stability of the vibration buffering process. Meanwhile, the mounting plate 15, which is fixedly connected to the bottom of the shock absorber 14, is firmly fixed to the mounting surface through the mounting hole 17, providing a stable support foundation for the entire shock absorption structure, preventing vibration from being transmitted to the mounting surface or affecting the motor body in the reverse direction, and ultimately achieving effective buffering and suppression of motor operation vibration, ensuring the stability of motor operation.

[0040] Please see Figure 9 , Figure 10 The second embodiment of the present invention provides a permanent magnet motor temperature rise suppression system encapsulated with phase change material, which includes: a temperature sensor (such as 2 to 4 miniature thermocouple array sensors with a temperature measurement accuracy of ≤ ±0.5℃, used to collect the spatial temperature gradient distribution of the phase change material in the cavity in real time) evenly distributed along the axial direction in a sealed cavity, a flow control valve, a variable frequency water pump, an edge computing controller, and a permanent magnet motor temperature rise suppression device encapsulated with phase change material as described above. The edge computing controller is configured to perform the following steps by executing a model predictive control algorithm based on dynamic observation of the phase ratio of a phase change liquid, which is stored internally: Real-time acquisition of collected data, including the operating current, speed, surface temperature of the permanent magnet motor body 1, and the temperature difference between the inlet and outlet water of the curved cooling pipe 5; Based on the collected data, and according to the preset phase change material liquid phase rate dynamic observer, combined with the equivalent thermal conductivity model of three-dimensional graphene aerogel, the real-time liquid phase rate of the phase change material in the sealed cavity is calculated. Based on the real-time liquid phase ratio and motor heat generation power prediction model, before the real-time liquid phase ratio reaches the preset depletion threshold, the optimal cooling water flow increment is solved through a cost function, and control commands are output to the variable frequency water pump in advance to achieve feedforward cooling scheduling. The liquid phase ratio depletion threshold is an adaptive dynamic threshold, and the edge computing controller uses the predicted motor load power P over the next N control cycles. e (k+i), automatic threshold adjustment: when it is predicted that the motor is about to enter a sustained high load range (Pe >0.8P rated When the motor is under light load, the depletion threshold is tightened from the default value of 0.85 to 0.70-0.75 in advance, triggering earlier feedforward active compensation cooling; when the motor is under light load, the threshold is dynamically relaxed to 0.90 to reduce the number of invalid start-stop cycles of the variable frequency water pump; the motor load power prediction value is predicted based on the real-time data of motor operating current and speed through a sliding window autoregressive model (AR model, order p=3), and the prediction step size is consistent with the MPC prediction step size Np, thereby maximizing the latent heat utilization rate of phase change material and achieving the optimal balance between cooling system energy consumption.

[0041] In this embodiment, the edge computing controller, based on the aforementioned temperature gradient data and combined with the thermal resistance network model of the biomimetic micro-rib array, identifies the spatial position of the solid-liquid two-phase interface of the phase change material within the sealed cavity online, thereby achieving dynamic tracking of the liquid-solid phase change front. Simultaneously, the controller performs spatial resolution correction on the integral calculation of the liquid phase rate observer based on the advancing speed and position information of the phase change front, reducing the prediction error of the MPC controller for the remaining latent heat of the phase change material by more than 30%, effectively preventing the risk of premature depletion of the phase change material and local runaway of motor temperature caused by local hot spots.

[0042] Specifically, firstly, the edge computing controller acquires the motor's operating parameters in real time, including the motor's operating current I and speed. Surface temperature T s And the water temperature difference, and calculate the real-time total heat loss Q. loss Considering copper and iron losses, the formula for calculating heat loss is: , For stator resistance, , Here, denoted by eddy current loss and hysteresis loss coefficients, and B represents the magnetic flux density.

[0043] Secondly, a dynamic energy balance model for three-dimensional graphene phase change materials was constructed. Due to the coupled thermal conductivity of the microrib array and graphene network, its heat transfer efficiency is extremely high. The controller calculates the liquid fraction of the phase change material based on real-time heat loss and heat removed by water cooling. (0 represents all solid state, 1 represents all liquid state, i.e., latent heat depletion). ,in, For real-time cooling water flow, For the temperature difference between the inlet and outlet water, For the quality of phase change materials, The effective latent heat value of graphene composite phase change materials.

[0044] Subsequently, to prevent the liquid phase ratio from reaching 1 (leading to latent heat depletion and a runaway temperature spike in the motor), the controller employs a model predictive control (MPC) algorithm for rolling flow optimization. The prediction step size is set to N.p The control step size is N. c At each sampling time k, the controller aims to minimize temperature deviation and pump energy consumption by solving the following objective cost function J: ,in, , , These are the weighting coefficients. The exponential term. The core penalty term of this invention: when the liquid phase ratio is predicted... When approaching a threshold (e.g., 0.85), the exponential penalty term... The rapid increase forces the MPC solver to significantly increase the cooling water flow rate increment in advance. The calculated PWM command is sent to the variable frequency water pump to achieve feedforward active heat extraction before the temperature changes abruptly.

[0045] Finally, after optimization, the controller will predict the first control input in the sequence. The command is issued to the variable frequency water pump for execution.

[0046] To further illustrate the effectiveness of this method, the parameters in the formulas involved in the above steps are explained as follows: (Heat loss) Taking a 7.5kW rated permanent magnet motor as an example, R s =2.8Ω, k e =0.012 W·s² / rad², kh=0.008 W·s / rad, x=1.8, Q under rated operating conditions loss ≈320W; (Liquid phase fraction observation) in, c p =4186J / (kg·K),ρ=998kg / m³,m pcm =3.2kg, ΔH eff =208 J / g = 208000 J / kg; After enabling the thermocouple array, the global liquid fraction correction formula is: i=1,...,4, weight w i By determining the PCM mass ratio of each partition (e.g., w1=0.30, w2=0.25, w3=0.25, w4=0.20), the liquid phase fraction prediction error can be reduced from ±22% to ±7%; (MPC cost function) key parameters are shown in Table 2, target temperature T ref =65℃, flow rate constraint q∈[2,12]L / min. After enabling adaptive thresholding, when the AR model (order p=3, window length L=30 sampling points) predicts P e (k+N p When the power consumption is greater than 0.8 × 7500 = 6000W, the depletion threshold automatically tightens from 0.85 to 0.72, triggering feedforward pre-compensation about 12 minutes in advance. The measured average number of ineffective start-stop cycles of the variable frequency water pump is reduced by about 61%.

[0047] Please see Figure 8 , Figure 8 The temperature rise comparison curve test conditions are provided: the rated power of the permanent magnet motor under test is 7.5kW, the rated speed is 1500rpm, and the equivalent resistance of the stator winding is R. s =2.8Ω, air gap magnetic flux density B=0.85T; ambient temperature 25℃, initial cooling water flow rate q0=6L / min (approximately 1.0×10⁻⁶). -4 m³ / s), cooling water inlet temperature 20℃; three-dimensional graphene aerogel composite phase change material filling mass m pcm =3.2kg (cavity volume filling rate 85%), equivalent latent heat of phase change ΔH eff =208 J / g; the test condition was continuous operation of the motor at full rated power for 60 minutes. Comparison curve A (ordinary air cooling) uses the original cooling fan; curve B (conventional water cooling + ordinary phase change) uses a heat-conducting plate of the same size + ordinary paraffin (λ=0.25W / (m·K)) + conventional PID control; curve C (this invention) uses a three-dimensional graphene aerogel PCM + MPC algorithm, with MPC parameters shown in Table 2. Table 1 provides a comparison of the thermophysical properties of the phase change material of this invention with traditional phase change materials.

[0048] Table 1:

[0049] Table 2: Key Parameters and Selection Criteria for MPC Control System

[0050] Note: The above MPC parameters are based on simulation optimization of a 7.5kW rated permanent magnet motor thermal model (MATLAB / Simulink2023a, ode45 solver). In practical applications, N p N c T s These parameters can be self-tuned online based on the motor's thermal response time constant.

[0051] In the extreme full-load operation test for 60 minutes ( Figure 8 (Curve C) The motor temperature of the present invention reaches a stable phase change heat absorption "plateau" at around 50°C. Subsequently, with the intervention of active water cooling by the MPC algorithm, the temperature remains stable within the safe range of 65°C, reducing the risk of temperature runaway that may occur in ordinary air cooling or single water cooling solutions.

[0052] Table 3 shows a comparison of the thermal management performance of the present invention and the prior art (7.5kW permanent magnet motor, 60min test under rated operating conditions).

[0053] Table 3:

[0054] In summary, at the hardware structure and material level, this invention upgrades traditional phase change materials to composite phase change materials with three-dimensional graphene aerogel shaping and encapsulation, and adds a biomimetic high thermal conductivity micro-rib array to the outer wall of the cooling pipe; at the control system level, this invention introduces a variable frequency water pump and an edge computing controller, and the controller has a built-in model predictive control algorithm based on dynamic observation of the phase rate of the phase change liquid.

[0055] Compared with the prior art, the present invention has the following beneficial effects: 1. By installing thermally conductive silicone grease 2, heat-conducting plate 3, curved cooling pipe 5, water inlet connector 6, water inlet pipe 7, water outlet connector 8, water outlet pipe 9, and heat dissipation fins 10, the thermally conductive silicone grease 2 is used to conduct the heat of the motor to the heat-conducting plate 3, and the cooling water is introduced into the curved cooling pipe 5 through the water inlet pipe 7 and then discharged through the water outlet pipe 9 to complete the water cooling cycle. With the setting of the heat-conducting plate 3, the water pump motor is protected by water cooling, and the heat dissipation fins 10 are used to further dissipate the heat, thereby preventing the motor from overheating and playing a temperature protection role to ensure the normal operation of the permanent magnet motor, effectively solving the problems and shortcomings of existing motors. 2. The permanent magnet motor is supported by multiple sets of support columns 12, guide sliders 13, shock absorbers 14, mounting plates 15, springs 16, and mounting holes 17. The shock-absorbing structure composed of shock absorbers 14, guide sliders 13, springs 16, and mounting plates 15 can buffer and reduce the vibration generated during motor operation, preventing vibration from affecting the overall stability of the water pump motor and resulting in better performance. 3. The reinforcing ribs 18 enhance the connection rigidity between the motor and the housing; the phase change material is sealed (with reserved expansion space) to prevent leakage; the cooling pipe joint uses threaded seals + fluororubber sealing rings to prevent cooling medium leakage; there are no false welds at any welding points, ensuring long-term operational stability. 4. Solving the problems of leakage and heat accumulation: the micropores of the aerogel firmly lock the liquid phase change core material through capillary surface tension, achieving "macroscopic solidification" even in a high-temperature liquefied state, with a leakage rate of less than 0.5%. Meanwhile, the three-dimensional graphene framework increases the thermal conductivity of the composite material by more than 10 times (reaching 2.85 W / m·K), greatly accelerating heat diffusion. 6. Nonlinear synergistic thermodynamic cycle: The biomimetic micro-rib array penetrates the aerogel network, forming a synergistic loop of "active heat dissipation by water cooling - thermally conductive bridge by micro-ribs - diffusion through the aerogel network - absorption of latent heat from phase change." 7. Algorithm-enabled feedforward temperature control: Breaking through the limitations of traditional passive water cooling, a novel liquid phase rate observation mechanism is pioneered. By using the MPC algorithm, the water pump flow rate is increased in advance to "actively extract heat" before the latent heat of the phase change material is about to be exhausted, achieving true constant temperature protection while reducing the energy consumption of ineffective pump start-stop. Adaptive threshold control: The depletion threshold is dynamically tightened / relaxed based on motor load prediction, combined with AR sliding window load prediction, to further optimize the latent heat utilization rate and the energy efficiency ratio of the cooling system. Phase change front spatial tracking: Thermocouple array and thermal resistance network in the cavity collaboratively track the position of the solid-liquid interface, which helps to reduce the error of liquid phase rate prediction and reduce the risk of unexpected depletion of latent heat caused by local hot spots, significantly improving the reliability of system thermal management.

[0056] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A temperature rise suppression device for a permanent magnet motor encapsulated with phase change material, characterized in that, include: The system comprises a permanent magnet motor body, thermal grease, a heat-conducting plate, a curved cooling pipe, and a mounting shell. The mounting shell covers the front end and sidewall periphery of the permanent magnet motor body, forming a sealed cavity that connects the front end and sidewall regions of the permanent magnet motor body. The thermal grease is applied to the front end of the permanent magnet motor body. The heat-conducting plate is embedded in the front end region of the sealed cavity and is tightly bonded to the front end of the permanent magnet motor body through the thermal grease. The sealed cavity is filled with a shaped composite phase change material. An installation groove is provided through the interior of the heat-conducting plate, and a curved cooling pipe is installed inside the installation groove. A biomimetic high thermal conductivity microrib array is arranged in an alternating pattern on the outer wall of the curved cooling pipe. The biomimetic high thermal conductivity microrib array penetrates the directional pores of the support skeleton of the shaped composite phase change material and is embedded in the matrix of the shaped composite phase change material, forming a synergistic temperature rise suppression pathway of active water cooling heat dissipation and passive absorption of latent heat of phase change. The shaped composite phase change material is used to absorb and store the heat generated by the permanent magnet motor body, and the curved cooling pipe is used to circulate the cooling medium and dissipate the heat from the heat-conducting plate and the sealed cavity.

2. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 1, characterized in that, The shaped composite phase change material occupies 80-90% of the sealed cavity volume. The shaped composite phase change material is a three-dimensional graphene aerogel shaped and encapsulated composite phase change material, which includes a matrix and a supporting skeleton. The matrix is ​​cured in the supporting skeleton by a vacuum impregnation process. The matrix is ​​a core material of paraffin wax and octadecanoic acid mixed in a 3:1 ratio, with a phase change temperature of 45-60℃ and a latent heat of phase change ≥200J / g. The supporting skeleton is a three-dimensional graphene aerogel with a multi-level porous structure, with an equivalent thermal conductivity ≥2.85W / m·K and a leakage rate <0.5%.

3. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 1, characterized in that, It also includes an outlet connector, an outlet pipe, an inlet connector, and an inlet pipe. The outlet connector is located at the first end of the curved cooling pipe. The first end of the curved cooling pipe is connected to the outlet pipe through the outlet connector. The second end of the curved cooling pipe is threaded to the inlet connector G1 / 2. A fluororubber sealing ring is provided at this connection. The second end of the curved cooling pipe is connected to the inlet pipe through the inlet connector. The inlet pipe is a nylon-reinforced flexible hose with an inner diameter of 8-12mm and a pressure resistance rating of ≥1.0MPa. The inlet pipe is wrapped with thermal insulation cotton.

4. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 1, characterized in that, The curved cooling pipe is arranged in a continuous S-shape and is made of stainless steel or copper. The total length of the curved cooling pipe is 3-5 times that of the heat conduction plate. The cooling medium flowing inside the pipe is cooling water or a 5% ethylene glycol aqueous solution.

5. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 1, characterized in that, The heat-conducting plate has multiple sets of heat dissipation fins at its top and bottom, and the heat dissipation fins are located in front of the permanent magnet motor body. Each heat dissipation fin has a micro-pit with a diameter of 1-2 mm and a depth of 0.5 mm on its surface. The heat dissipation fins are made of aluminum-magnesium alloy, with a single fin thickness of 1-1.5 mm and a spacing of 3-5 mm. Each set of heat dissipation fins has 15-25 fins, and they are integrally extruded or welded to the heat-conducting plate. The heat-conducting plate is made of 6061 aluminum alloy or copper, with a thickness of 8-12 mm and a surface roughness Ra≤0.8μm.

6. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 1, characterized in that, The permanent magnet motor body has four fixed bases at its bottom corners. Each fixed base is fixedly connected to a support column at its bottom. Each support column has a guide slider at its bottom end. The fixed bases are detachably connected to the permanent magnet motor body by M8-M10 bolts. The support columns, fixed bases, and guide sliders are all fixed by argon arc welding. The support columns are made of Q235 steel with a diameter of 15-20mm and a length of 30-40mm.

7. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 6, characterized in that, The guide slider is slidably connected to a shock absorber, and the bottom of the shock absorber is fixedly connected to a mounting plate. The top of the mounting plate is provided with mounting holes at equal intervals. The outer wall of the guide slider is clearance-fitted with the inner wall of the shock absorber. The guide slider is made of 45# steel with a hard chrome plated surface and a thickness of 0.05-0.1mm. The shock absorber is made of seamless steel pipe with an inner diameter of 25-30mm and a length of 40-50mm. Multiple sets of springs are installed equidistantly inside the shock absorber. One end of each spring is fixedly connected to the bottom of the guide slider. The springs are cylindrical helical compression springs. Each set of shock absorbers contains 3-5 springs. The springs, guide sliders, and shock absorbers are all welded together.

8. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 1, characterized in that, The outer wall of the permanent magnet motor body is provided with multiple sets of reinforcing ribs at equal intervals. One side surface of each reinforcing rib is fixedly connected to the mounting shell. The reinforcing ribs are made of 6061 aluminum alloy with a thickness of 3-5mm and an adjacent spacing of 15-20mm. The reinforcing ribs are welded to the permanent magnet motor body and the mounting shell. The mounting shell is made of cold-rolled steel plate with a thickness of 2-3mm. The surface of the cold-rolled steel plate is sprayed with a high-temperature resistant and anti-corrosion coating with a thickness of 0.1-0.2mm.

9. The permanent magnet motor temperature rise suppression device using phase change material encapsulation according to claim 1, characterized in that, The thermal conductivity of the thermal grease is ≥1.5W / (m). The biomimetic high thermal conductivity microrib array is made of OFHC copper with a thickness of 0.5-1mm; the microrib array is made of OFHC copper with a thermal conductivity ≥400W / (m²). K) is a cylindrical needle-fin array structure with a needle-fin diameter of 1.5~2.0mm, a height of 8~12mm, a horizontal spacing of 3~4mm, a vertical spacing of 2~3mm, and adjacent rows of needle-fins are arranged alternately. The root of the needle-fins and the outer wall of the curved cooling pipe are solidified and connected in a vacuum brazing furnace using BCu-1 type copper-based brazing filler metal.

10. A temperature rise suppression system for a permanent magnet motor using phase change material encapsulation, characterized in that, include: A temperature sensor, a flow control valve, a variable frequency water pump, an edge computing controller, and a permanent magnet motor temperature rise suppression device encapsulated with phase change material as described in any one of claims 1 to 9 are uniformly distributed along the axial direction within a sealed cavity. The edge computing controller is configured to perform the following steps by executing a model predictive control algorithm based on dynamic observation of the phase ratio of a phase change liquid, which is stored internally: Real-time acquisition of collected data, including the operating current, speed, surface temperature of the permanent magnet motor body, and the temperature difference between the inlet and outlet water of the curved cooling pipe; Based on the collected data, and according to the preset phase change material liquid phase rate dynamic observer, combined with the equivalent thermal conductivity model of three-dimensional graphene aerogel, the real-time liquid phase rate of the phase change material in the sealed cavity is calculated. Based on the real-time liquid phase ratio and motor heat generation power prediction model, before the real-time liquid phase ratio reaches the preset depletion threshold, the optimal cooling water flow increment is solved through the cost function, and the control command is output to the variable frequency water pump in advance to realize feedforward cooling scheduling.

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