Efficient heat dissipation system and method of permanent magnet synchronous motor

Abstract

The invention provides an efficient heat dissipation system and method for a permanent magnet synchronous motor, and the system comprises a stator cooling module which releases the heat of a stator through the combination of cooling water circulation outside the stator and air gap ventilation; the rotor heat dissipation module jointly drives magnetic fluid in a rotor rotating shaft to flow through rotating centrifugal force of a rotor and an external magnetic field, and releases rotor heat when the magnetic fluid flows through external heat dissipation fins; the permanent magnet heat conduction module transmits heat to a magnetic fluid in a rotor rotating shaft through a heat conduction material in a permanent magnet, and then the magnetic fluid releases the heat of the permanent magnet; and the temperature control adjusting unit is used for collecting temperature data of the stator, the rotor and the permanent magnet in real time and outputting a corresponding control signal based on the temperature data to control the cooling water circulation rate of the stator area and / or the magnetic fluid flow rate of the rotor area. The problems that most of existing heat dissipation schemes are low in heat dissipation efficiency, the stator, the rotor and the permanent magnet cannot be subjected to comprehensive heat dissipation, and the heat dissipation intensity cannot be dynamically adjusted are solved.

Description

Technical Field

[0001] This invention relates to the field of motor heat dissipation technology, and in particular to a high-efficiency heat dissipation system and method for a permanent magnet synchronous motor. Background Technology

[0002] With the surge in global demand for clean energy, variable-speed constant-frequency hydropower systems have become the mainstream development direction in the hydropower field due to their ability to adapt to head fluctuations and improve water energy utilization. In this system, permanent magnet synchronous motors (PMSMs) are widely used as core components for power generation due to their advantages such as high power density, high operating efficiency, and fast response speed.

[0003] However, permanent magnet synchronous motors (PMSMs) face severe heat dissipation challenges during variable-speed operation. Specifically, stator copper losses, rotor iron losses, and eddy current losses in the permanent magnets generate significant heat during operation. Furthermore, the humid and enclosed nature of most hydropower stations exacerbates this heat buildup. If this heat cannot be dissipated promptly, it can lead to aging of the stator winding insulation, shortening the motor's lifespan and even causing short-circuit faults. It can also cause irreversible demagnetization of the permanent magnets, reducing the motor's output power and power generation efficiency. Therefore, developing efficient heat dissipation technologies for PMSMs in variable-speed constant-frequency hydropower systems is crucial for ensuring stable and efficient system operation.

[0004] Currently, the mainstream heat dissipation solutions for permanent magnet synchronous motors have many problems, specifically: (1) When using natural cooling, the heat dissipation efficiency is extremely low due to the reliance on natural convection between the motor casing and the air. This is only suitable for low-power (≤50kW) motors. At the same time, when the load fluctuates under variable speed conditions, the heat dissipation demand cannot be met, and the motor temperature rise is likely to exceed the threshold. (2) When using forced air cooling, the air is forced to blow by the motor's built-in fan and flows over the stator and rotor surfaces to remove heat. Since the fan operation generates additional energy consumption, it reduces the overall efficiency of the system. At the same time, the dust and moisture carried by the air are likely to adhere to the windings and permanent magnet surfaces, which may cause insulation failure or permanent magnet failure. Corrosion of the body, and the maintenance frequency is extremely high in humid environments such as hydropower stations. In addition, the rotor and permanent magnet are located inside the motor, and the air-cooled airflow is difficult to penetrate, resulting in poor heat dissipation in this area. (3) When using the traditional water cooling method for heat dissipation, a single-loop water cooling pipe is usually set on the outer periphery of the stator core. The heat of the stator is carried away by the cooling water circulation. The heat dissipation path of this heat dissipation method is single and can only be used for heat dissipation of the stator. The heat of the rotor and permanent magnet cannot be effectively discharged, which easily forms a "local high temperature zone". At the same time, the water cooling pipe adopts a single-loop design, and the water flow speed is uniform. It is impossible to dynamically adjust the heat dissipation intensity according to the heat change under the variable speed condition. In addition, there are many pipe joints, which pose a risk of leakage. Once water leaks, it will directly cause the motor to short circuit, resulting in low safety. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a high-efficiency heat dissipation system and method for permanent magnet synchronous motors, which solves the problems that most heat dissipation solutions in the existing technology have low heat dissipation efficiency, cannot dissipate heat from the stator, rotor and permanent magnets in an all-round way, and cannot dynamically adjust the heat dissipation intensity.

[0006] According to an embodiment of the present invention, a high-efficiency heat dissipation system for a permanent magnet synchronous motor is provided. The permanent magnet synchronous motor includes a stator, a rotor, and permanent magnets. The heat dissipation system includes: The stator cooling module combines external cooling water circulation with air gap ventilation to release heat from the stator, thereby achieving heat dissipation for the stator. The rotor heat dissipation module uses the centrifugal force of the rotor's rotation and an external magnetic field to drive the flow of the magnetofluid filling the rotor shaft, and releases the rotor's heat as the magnetofluid flows through the external heat dissipation fins, thereby achieving heat dissipation for the rotor. The permanent magnet heat conduction module transfers the heat of the permanent magnet to the magnetofluid inside the rotor shaft through the heat-conducting material filled inside the permanent magnet, and then the magnetofluid releases the heat of the permanent magnet, thereby achieving heat dissipation of the permanent magnet; The temperature control unit collects real-time temperature data of the stator, the rotor, and the permanent magnet, and outputs corresponding control signals based on the collected temperature data to control the cooling water circulation rate in the stator region and / or the magnetohydrodynamic flow rate in the rotor region.

[0007] On the other hand, according to embodiments of the present invention, a high-efficiency heat dissipation method for a permanent magnet synchronous motor is also provided, the heat dissipation method comprising the following steps: When the motor is running, the heat generated by the stator copper loss is transferred to the stator core. The heat is released by the cooling water circulation outside the stator and the air gap ventilation, thus completing the heat dissipation of the stator area. Meanwhile, the heat generated by the rotor iron loss is transferred to the rotor shaft, and the heat from the eddy current loss of the permanent magnet is conducted to the rotor shaft through the thermally conductive material filled in the permanent magnet. When the rotor shaft rotates, the magnetic fluid filled in the rotor shaft circulates under the combined drive of centrifugal force and external magnetic field, and releases heat when the magnetic fluid flows through the external heat dissipation fins, thus completing the heat dissipation of the rotor and the permanent magnet area. During the heat dissipation process, the temperature data of the stator, the rotor and the permanent magnet are collected in real time, and corresponding control signals are output based on the collected temperature data to control the cooling water circulation rate in the stator region and / or the magnetohydrodynamic flow rate in the rotor region.

[0008] Compared with the prior art, the present invention has the following beneficial effects: The stator is cooled by a synergistic heat dissipation method combining external cooling water circulation and air gap ventilation. This increases the heat exchange area and, combined with air gap convection, improves the stator's heat dissipation efficiency, solving the problem of high-efficiency stator heat dissipation. The rotor shaft's magnetofluid circulates under the combined drive of centrifugal force and an external magnetic field, releasing rotor heat as it flows past external heat dissipation fins, achieving lossless heat dissipation. The permanent magnet's heat is transferred to the magnetofluid within the rotor shaft via the thermally conductive material, and then released by the magnetofluid, creating an effective heat conduction path and resolving the heat dissipation bottleneck within the permanent magnet. By collecting temperature data from the stator, rotor, and permanent magnet, and outputting corresponding control signals to control the cooling water circulation rate in the stator region and / or the magnetofluid flow rate in the rotor region, dynamic matching of heat dissipation intensity with variable speed operation is achieved, solving the problem that existing heat dissipation solutions cannot dynamically adjust heat dissipation intensity. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the overall assembly structure of a high-efficiency heat dissipation system for a permanent magnet synchronous motor according to an embodiment of the present invention and the permanent magnet synchronous motor.

[0010] Figure 2 This is a top view of the stator core laminations and air gap ventilation slots according to an embodiment of the present invention.

[0011] Figure 3 This is a cross-sectional view of the rotor shaft and the magnetofluid annular flow channel according to an embodiment of the present invention.

[0012] Figure 4 This is a side view of the permanent magnet and heat dissipation holes according to an embodiment of the present invention.

[0013] Figure 5 This is a control principle diagram of the temperature control unit in an embodiment of the present invention.

[0014] Figure 6 This is a flowchart illustrating a high-efficiency heat dissipation method for a permanent magnet synchronous motor according to another embodiment of the present invention.

[0015] Figure 7 The diagram illustrates the specific steps of controlling the cooling water circulation rate in the stator region and / or the magnetohydrodynamic flow rate in the rotor region based on the collected temperature data, according to another embodiment of the present invention.

[0016] In the above figures: 1. Stator; 2. Rotor; 3. Permanent magnet; 11. Stator core; 12. Core lamination; 21. Rotor shaft; 41. Double helix water cooling channel; 42. Air gap ventilation slot; 51. Annular flow channel; 52. Magnetic field coil; 53. Magnetorheological fluid; 61. Heat dissipation hole; 62. Thermally conductive filling layer; 71. Flow regulating valve; 72. Magnetic field regulator; 73. Temperature sensor; 74. PLC controller. Detailed Implementation

[0017] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] like Figures 1-5 As shown in the figure, this embodiment of the invention proposes a high-efficiency heat dissipation system for a permanent magnet synchronous motor. The permanent magnet synchronous motor includes a stator 1, a rotor 2, and a permanent magnet 3. The heat dissipation system includes: The stator cooling module combines cooling water circulation outside the stator 1 with air gap ventilation to release heat from the stator 1, thereby achieving heat dissipation for the stator 1. The rotor heat dissipation module uses the centrifugal force of the rotor 2 and the external magnetic field to drive the flow of the magnetic fluid 53 filled in the rotor shaft 21, and releases the heat of the rotor 2 when the magnetic fluid 53 flows through the external heat dissipation fins, thereby achieving heat dissipation of the rotor 2. The permanent magnet heat conduction module transfers the heat of the permanent magnet 3 to the magnetofluid 53 inside the rotor shaft 21 through the heat-conducting material filled inside the permanent magnet 3, and then the magnetofluid 53 releases the heat of the permanent magnet 3, thereby achieving heat dissipation of the permanent magnet 3. The temperature control unit collects temperature data of the stator 1, the rotor 2 and the permanent magnet 3 in real time, and outputs corresponding control signals based on the collected temperature data to control the cooling water circulation rate in the stator 1 area and / or the flow rate of the magnetofluid 53 in the rotor 2 area.

[0019] Specifically, the stator cooling module dissipates heat from the stator 1 through a combined cooling water circulation and air gap ventilation method. The cooling water circulation increases the heat exchange area of ​​the stator 1, and the air gap convection ventilation further enhances heat dissipation, thereby improving the heat dissipation efficiency of the stator 1 and solving the problem of high-efficiency heat dissipation. The rotor heat dissipation module utilizes the magnetic fluid 53 within the rotor shaft 21, which circulates under the combined drive of centrifugal force and an external magnetic field. The magnetic fluid 53 releases heat from the rotor 2 as it flows through the external heat dissipation fins, achieving heat dissipation of the rotor 2 without mechanical loss. The permanent magnet heat conduction module utilizes the permanent magnet... The heat-conducting material inside the body 3 transfers the heat from the permanent magnet 3 to the magnetic fluid 53 inside the rotor shaft 21, and then releases it from the magnetic fluid 53, thereby constructing an effective heat conduction path to transfer the heat out, solving the heat dissipation bottleneck inside the permanent magnet 3; the temperature control unit collects the temperature data of the stator 1, the rotor 2 and the permanent magnet 3, and outputs corresponding control signals based on the collected temperature data to control the cooling water circulation rate in the stator 1 area and / or the flow rate of the magnetic fluid 53 in the rotor 2 area, realizing dynamic matching between heat dissipation intensity and variable speed operation, solving the problem that existing heat dissipation solutions cannot dynamically adjust the heat dissipation intensity.

[0020] Furthermore, the stator cooling module includes a double-helix water-cooling channel 41 and an air gap ventilation slot 42, wherein: The double-helix water-cooling channel 41 is arranged around the outer periphery of the stator core 11 of the stator 1, and the inlet and outlet of the double-helix water-cooling channel 41 are respectively connected to the cooling water circulation system of the hydropower station; the core laminations 12 of the stator 1 are evenly opened radially with the air gap ventilation slots 42, and the slot openings of the air gap ventilation slots 42 are connected to the gap between the stator 1 and the rotor 2 to form an air convection channel.

[0021] Specifically, the inlet and outlet of the double-helix water-cooling channel 41 are respectively connected to the cooling water circulation system of the hydropower station. The inlet introduces low-temperature cooling water into the double-helix water-cooling channel 41, while the outlet discharges the high-temperature cooling water that has absorbed heat, returning it to the cooling water circulation system for cooling treatment so that it can be recycled again. The double-helix water-cooling channel 41 is made of 304 stainless steel. The double-helix water-cooling channel 41 is wound around the outer circumference of the stator core 11 of the stator 1, with a helix angle of 30°-45° and an inner diameter of 8-12mm. Compared with traditional straight or simple annular water-cooling channels, the double-helix structure increases the contact path length between the cooling water and the stator core 11, allowing the cooling water to absorb the heat generated by the stator 1 more fully.

[0022] It is worth noting that, in addition to using the double-helix water-cooling channel 41 for cooling water circulation, micro water-cooling channels with a diameter of 0.5-1mm can also be opened axially inside the stator core 11 of the stator 1. Each stator core lamination 12 has 20-30 micro water-cooling channels. The cooling water carries away heat through the permeation flow in the micro water-cooling channels, thereby achieving water-cooled heat dissipation of the stator 1. Compared with the double-helix water-cooling channel 41, the heat dissipation is more uniform and it is suitable for higher power motors. However, the micro water-cooling channels are more difficult to process and the cost is higher than that of the double-helix water-cooling channel 41. It is suitable for scenarios with extremely high requirements for heat dissipation uniformity.

[0023] The stator 1 is formed by stacking multiple core laminations 12 (8-12 pieces). During the manufacturing of the core laminations 12, air gap ventilation slots 42 (8-12 in number, 5-8 mm wide) are evenly opened along the radial direction of the laminations (extending from the center of the laminations to the periphery). The openings of the air gap ventilation slots 42 are connected to the gap between the stator 1 and the rotor 2, allowing air to flow along a specific path and forming effective air convection. This effectively removes the heat generated by the stator 1, enhancing the heat dissipation effect. At the same time, combined with the cooling water circulation of the double helix water cooling channel 41, the heat dissipation efficiency of the stator 1 can be improved, achieving efficient heat dissipation of the stator 1.

[0024] Furthermore, the rotor heat dissipation module includes an annular flow channel 51 and a magnetic field coil 52, wherein: The rotor shaft 21 has an annular flow channel 51 inside along the circumferential direction, and the annular flow channel 51 is filled with magnetofluid 53; the magnetic field coil 52 is wound on a fixed bracket outside the rotor shaft 21; the two ends of the annular flow channel 51 are connected to external heat dissipation fins to form a closed loop flow.

[0025] Specifically, the annular flow channel 51 has a rectangular cross-section with a width of 10-15 mm and a depth of 8-12 mm. The magnetic fluid 53 is made by mixing Fe3O4 nanoparticles with a mixed solution of ethylene glycol, and the concentration of Fe3O4 nanoparticles is 5-8%. The magnetic field coil 52 is wound around a fixed bracket outside the rotor shaft 21 (the fixed bracket does not rotate with the rotor 2). The two ends of the annular flow channel 51 are connected to the external heat dissipation fins through sealed bearings, forming a closed and efficient heat conduction channel. This allows the heat carried by the magnetic fluid 53 to be quickly transferred to the external heat dissipation fins through the sealed bearings. Then, the heat dissipation fins increase the contact area with the air and dissipate the heat to the surrounding environment by natural convection or forced convection (such as fan drive), thereby achieving effective cooling of the rotor 2.

[0026] It is worth noting that, in addition to using a mixture of Fe3O4 nanoparticles and ethylene glycol to prepare the magnetic fluid 53, a mixture of CoFe2O4 nanoparticles and ethylene glycol can also be used to prepare the magnetic fluid 53. Although the thermal conductivity of CoFe2O4 nanoparticles is higher than that of Fe3O4 nanoparticles, resulting in higher heat dissipation efficiency, the material cost is higher, making it more suitable for motors operating under high temperature and harsh conditions.

[0027] Furthermore, the permanent magnet heat-conducting module includes heat dissipation holes 61 and a heat-conducting filling layer 62, wherein: The permanent magnet 3 has a heat dissipation hole 61 along the axial direction. The heat dissipation hole 61 is filled with the thermally conductive filling layer 62. The two ends of the thermally conductive filling layer 62 are in contact with the inner wall of the annular flow channel 51 and the surface of the permanent magnet 3, respectively, forming a heat conduction path.

[0028] Specifically, the heat dissipation holes 61 are opened along the axial direction of the permanent magnet 3, with a diameter of 1-2 mm, a hole spacing of 5-8 mm, and a hole depth consistent with the length of the permanent magnet 3. The heat dissipation holes 61 are filled with the thermally conductive filling layer 62. The heat dissipation holes 61 provide a channel for heat transfer, and the thermally conductive filling layer 62 inside the heat dissipation holes 61 accelerates the conduction of heat from the inside of the permanent magnet 3 to the outside. Since the two ends of the thermally conductive filling layer 62 are in contact with the inner wall of the annular flow channel 51 and the surface of the permanent magnet 3, the heat generated by the permanent magnet 3 can be quickly transferred from the thermally conductive filling layer 62 to the annular flow channel 51 of the rotor 2. Then, with the help of the annular flow channel 51 and its connected external heat dissipation fins, the heat is dissipated to the surrounding environment, thereby achieving heat dissipation of the permanent magnet 3.

[0029] Preferably, the thermally conductive filler layer 62 is made of graphene composite material, and the thermal conductivity of the graphene composite material is ≥500W / (m). K), thereby enabling the heat generated by the permanent magnet 3 to be discharged at an extremely fast speed, greatly improving the heat dissipation efficiency of the permanent magnet 3. At the same time, the graphene composite material also has good chemical stability and mechanical properties. During long-term contact with the permanent magnet 3 and the annular flow channel 51, it can maintain stable physical and chemical properties and is not prone to corrosion, deformation and other problems, ensuring the long-term reliable operation of the permanent magnet heat conduction module.

[0030] It is worth noting that, in addition to using graphene composite material as the thermally conductive filling layer 62, silicon carbide (SiC) composite material can also be used as the thermally conductive filling layer 62. Silicon carbide composite material has better temperature resistance than graphene composite material and stronger corrosion resistance, making it more suitable for hydropower stations with poor water quality. However, the thermal conductivity of silicon carbide composite material is lower than that of graphene composite material, so the number of heat dissipation holes 61 needs to be appropriately increased to ensure the thermal conductivity.

[0031] Furthermore, the temperature control unit includes a flow regulating valve 71 and a magnetic field regulator 72, wherein: The flow regulating valve 71 is located in the middle of the cooling water circulation system of the hydropower station. It controls the cooling water circulation rate in the double helix water cooling channel 41 by adjusting its own flow rate. The magnetic field regulator 72 is electrically connected to the magnetic field coil 52 and controls the flow rate of the magnetic fluid 53 filled in the annular flow channel 51 by adjusting the magnetic field strength.

[0032] Specifically, the flow regulating valve 71 is installed in the middle of the hydropower station's cooling water circulation system, enabling it to directly and effectively regulate the water flow throughout the entire cooling water circulation system. The flow regulating valve 71 adjusts the flow rate by changing its opening. When it is necessary to increase the cooling water circulation rate within the double-helix water-cooling channel 41, the flow regulating valve 71 increases its opening, allowing more cooling water to pass through and thus accelerating the water flow. Conversely, when it is necessary to decrease the circulation rate, the flow regulating valve 71 decreases its opening, limiting the cooling water flow. This adjustment method is similar to controlling the water flow through a faucet; by adjusting the position of the valve core of the flow regulating valve 71, the cross-sectional area of ​​the channel is changed, thereby achieving precise control of the flow rate.

[0033] The magnetic field regulator 72 is electrically connected to the magnetic field coil 52 and is located in a control cabinet or dedicated equipment close to the magnetic field coil 52 to facilitate operation and maintenance of the magnetic field regulator 72. This also reduces interference during signal transmission, ensuring that the magnetic field regulator 72 can accurately receive and execute control commands. The magnetic field regulator 72 controls the magnetic field strength by adjusting the current input to the magnetic field coil 52, and controls the flow rate of the magnetic fluid 53 filled in the annular flow channel 51 based on the magnetic field strength. According to the principle of electromagnetic induction, a magnetic field is generated when current passes through the magnetic field coil 52. The larger the current, the stronger the magnetic field. This allows the magnetic field regulator 72 to precisely adjust the current according to actual needs, thereby controlling the flow rate of the magnetic fluid 53 in the annular flow channel 51. When the magnetic field strength increases, the Lorentz force on the magnetic fluid 53 increases, and the flow rate increases; when the magnetic field strength decreases, the Lorentz force on the magnetic fluid 53 decreases, and the flow rate decreases.

[0034] Furthermore, the temperature control unit also includes a temperature sensor 73 and a PLC controller 74, wherein: The number of temperature sensors 73 is several, which are respectively attached to the winding end of the stator 1, the iron core surface of the rotor 2 and the surface of the permanent magnet 3, for real-time acquisition of the temperature of the stator 1, the rotor 2 and the permanent magnet 3; The PLC controller 74 is used to receive temperature data sent by the temperature sensor 73, and output corresponding control signals based on the received temperature data to control the flow rate of the flow regulating valve 71 and / or the magnetic field strength of the magnetic field regulator 72.

[0035] Specifically, temperature sensors 73 (typically thermistors, thermocouples, or other temperature-sensing elements) are attached to the winding ends of the stator 1, the core surface of the rotor 2, and the surface of the permanent magnet 3. These temperature sensors 73 can collect temperature data in real time at the winding ends of the stator 1, the core surface of the rotor 2, and the surface of the permanent magnet 3. The collected temperature data is then transmitted wirelessly to the PLC controller 74 via a wireless transmission module (such as a Bluetooth Low Energy module). Upon receiving the temperature data, the PLC controller 74 outputs corresponding control signals to control the cooling water circulation rate in the stator 1 area and / or the flow rate of the magnetohydrodynamic fluid 53 in the rotor 2 area. Specifically, when the temperature of the stator 1, rotor 2, or permanent magnet 3 is detected to be too high, the PLC controller 74 outputs control signals to adjust the flow rate of the flow regulating valve 71 and / or the magnetic field. If the temperature of the stator 1 is too high, the PLC controller 74 will output a control signal to the flow regulating valve 71, increasing the opening of the flow regulating valve 71 to increase the circulation rate of the cooling water in the double-helix water-cooling channel 41 and accelerate the dissipation of heat from the stator 1. If the temperature of the rotor 2 or the permanent magnet 3 is too high, the PLC controller 74 will output a control signal to the magnetic field regulator 72, increasing the output current of the magnetic field regulator 72 and strengthening the magnetic field strength of the current passing through the magnetic field coil 52, thereby accelerating the flow rate of the magnetic fluid 53 filled in the annular flow channel 51 and accelerating the dissipation of heat from the rotor 2 or the permanent magnet 3. Conversely, when the temperature of the stator 1, the rotor 2, or the permanent magnet 3 is too low, the PLC controller 74 will correspondingly reduce the flow rate of the flow regulating valve 71 or the magnetic field strength of the magnetic field regulator 72 to avoid overcooling or energy waste.

[0036] Preferably, the number of temperature sensors 73 is at least 6, wherein 2 temperature sensors 73 are attached to the winding end of the stator 1 and the iron core surface of the rotor 2, and at least 2 temperature sensors 73 are attached to the surface of the permanent magnet 3 (2-4 temperature sensors 73 can be attached to the surface of the permanent magnet 3 to obtain temperature data at different positions on the surface of the permanent magnet 3, thereby improving the accuracy of judging the overall temperature condition of the permanent magnet 3), so as to comprehensively and accurately monitor the temperature of the stator 1, the rotor 2 and the permanent magnet 3 of the permanent magnet synchronous motor, thereby ensuring the safe and stable operation of the motor.

[0037] The detailed working process of this embodiment is as follows: During motor operation, the heat generated by the copper loss of stator 1 is transferred to stator core 11. At this time, low-temperature cooling water is introduced into the double-helix water-cooling channel 41 through the inlet of the hydropower station cooling water circulation system, and the low-temperature cooling water flows in the double-helix water-cooling channel 41. During the flow, the low-temperature cooling water absorbs the heat of stator 1 and is discharged from the outlet of the hydropower station cooling water circulation system, returning to the hydropower station cooling water circulation system for cooling treatment so that it can be recycled again. This achieves the circulation and heat dissipation of cooling water. At the same time, the slot of the air gap ventilation groove 42 is connected to the gap between stator 1 and rotor 2, allowing air to flow in a specific path and forming effective air convection. This can promptly remove the heat generated by stator 1, achieving air gap ventilation. The heat of stator 1 is released by the cooling water circulation outside stator 1 and the air gap ventilation, completing the heat dissipation of the stator 1 area and solving the problem of efficient heat dissipation of stator 1.

[0038] While the motor is running, the heat generated by the iron loss of the rotor 2 is transferred to the rotor shaft 21, and the heat from the eddy current loss of the permanent magnet 3 is conducted to the rotor shaft 21 through the thermally conductive material filled inside the permanent magnet 3. When the rotor shaft 21 rotates, the magnetofluid 53 filled inside the rotor shaft 21 circulates in the annular flow channel 51 under the combined drive of rotational centrifugal force and external magnetic field, and is quickly transferred to the external heat dissipation fins through the sealed bearing. Then, the heat dissipation fins increase the contact area with the air and dissipate the heat to the surrounding environment by utilizing natural or forced convection of the air, thereby achieving effective cooling of the rotor 2 and the permanent magnet 3, completing the heat dissipation of the rotor 2 and the permanent magnet 3 area, realizing heat dissipation of the rotor 2 without mechanical loss, and solving the heat dissipation bottleneck inside the permanent magnet 3.

[0039] During heat dissipation, temperature sensors 73, attached to the winding ends of the stator 1, the core surface of the rotor 2, and the surface of the permanent magnet 3, collect temperature data of the stator 1, rotor 2, and permanent magnet 3 in real time. The collected temperature data is then transmitted wirelessly to the PLC controller 74. Upon receiving the temperature data, the PLC controller 74 outputs corresponding control signals to control the cooling water circulation rate in the stator 1 area and / or the flow rate of the magnetofluid 53 in the rotor 2 area. Specifically, when the temperature of the stator 1, rotor 2, or permanent magnet 3 is detected to be too high, the PLC controller 74 outputs control signals to adjust the flow rate of the flow regulating valve 71 and / or the magnetic field strength of the magnetic field regulator 72. If the temperature of the stator 1 is too high, the PLC controller 74... 4 will output a control signal to the flow regulating valve 71, increasing the opening of the flow regulating valve 71 to increase the circulation rate of cooling water in the double helix water cooling channel 41 and accelerate the heat dissipation of the stator 1. If the temperature of the rotor 2 or the permanent magnet 3 is too high, the PLC controller 74 will output a control signal to the magnetic field regulator 72, increasing the output current of the magnetic field regulator 72 and strengthening the magnetic field strength of the current passing through the magnetic field coil 52, thereby accelerating the flow rate of the magnetic fluid 53 filled in the annular flow channel 51 and accelerating the heat dissipation of the rotor 2 or the permanent magnet 3. Conversely, when the temperature of the stator 1, the rotor 2, or the permanent magnet 3 is too low, the PLC controller 74 will correspondingly reduce the flow rate of the flow regulating valve 71 or the magnetic field strength of the magnetic field regulator 72 to avoid overcooling or energy waste. By collecting temperature data of the stator 1, the rotor 2 and the permanent magnet 3, and outputting corresponding control signals based on the collected temperature data to control the cooling water circulation rate in the stator 1 area and / or the flow rate of the magnetofluid 53 in the rotor 2 area, dynamic matching of heat dissipation intensity and speed change conditions is achieved, solving the problem that existing heat dissipation schemes cannot dynamically adjust heat dissipation intensity.

[0040] On the other hand, such as Figure 6 and Figure 7 As shown in the figure, this embodiment of the invention also provides a high-efficiency heat dissipation method for a permanent magnet synchronous motor, the heat dissipation method comprising the following steps: S1. When the motor is running, the heat generated by the copper loss of stator 1 is transferred to stator core 11. The heat of stator 1 is released through the cooling water circulation outside stator 1 and the air gap ventilation, thus completing the heat dissipation of the stator 1 area. S2. Simultaneously, the heat generated by the iron loss of rotor 2 is transferred to rotor shaft 21, and the heat from the eddy current loss of permanent magnet 3 is conducted to rotor shaft 21 through the thermally conductive material filled inside permanent magnet 3. When rotor shaft 21 rotates, the magnetic fluid 53 filled inside rotor shaft 21 circulates under the combined drive of centrifugal force and external magnetic field, and releases heat when the magnetic fluid 53 flows through external heat dissipation fins, thus completing the heat dissipation of rotor 2 and the area of ​​permanent magnet 3. S3. During the heat dissipation process, the temperature data of the stator 1, the rotor 2 and the permanent magnet 3 are collected in real time, and corresponding control signals are output based on the collected temperature data to control the cooling water circulation rate in the stator 1 area and / or the flow rate of the magnetofluid 53 in the rotor 2 area.

[0041] Furthermore, the step of outputting corresponding control signals based on the collected temperature data to control the cooling water circulation rate in the stator 1 region and / or the magnetofluid 53 flow rate in the rotor 2 region specifically includes: S31. Temperature sensors 73 are attached to the winding ends of stator 1, the iron core surface of rotor 2, and the surface of permanent magnet 3 respectively. Temperature data of stator 1, rotor 2 and permanent magnet 3 are collected in real time through the temperature sensors 73, and the collected temperature data is transmitted to PLC controller 74. S32. After receiving the temperature data, the PLC controller 74 compares the temperature data with the preset threshold of each region, and when the temperature data exceeds the preset threshold of the region, it outputs a corresponding control signal to the flow regulating valve 71 and / or the magnetic field regulator 72. S33. After receiving a control signal, the flow regulating valve 71 controls the cooling water circulation rate in the double helix water cooling channel 41 by adjusting its own flow rate; after receiving a control signal, the magnetic field regulator 72 controls the flow rate of the magnetic fluid 53 filled in the annular flow channel 51 by adjusting the magnetic field strength.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-efficiency heat dissipation system for a permanent magnet synchronous motor, the permanent magnet synchronous motor comprising a stator, a rotor, and permanent magnets, characterized in that, The heat dissipation system includes: The stator cooling module combines external cooling water circulation with air gap ventilation to release heat from the stator, thereby achieving heat dissipation for the stator. The rotor heat dissipation module uses the centrifugal force of the rotor's rotation and an external magnetic field to drive the flow of the magnetofluid filling the rotor shaft, and releases the rotor's heat as the magnetofluid flows through the external heat dissipation fins, thereby achieving heat dissipation for the rotor. The permanent magnet heat conduction module transfers the heat of the permanent magnet to the magnetofluid inside the rotor shaft through the heat-conducting material filled inside the permanent magnet, and then the magnetofluid releases the heat of the permanent magnet, thereby achieving heat dissipation of the permanent magnet; The temperature control unit collects real-time temperature data of the stator, the rotor, and the permanent magnet, and outputs corresponding control signals based on the collected temperature data to control the cooling water circulation rate in the stator region and / or the magnetohydrodynamic flow rate in the rotor region.

2. The high-efficiency heat dissipation system for a permanent magnet synchronous motor according to claim 1, characterized in that, The stator cooling module includes a double-helix water-cooling channel and an air gap ventilation slot, wherein: The double-helix water-cooling channel is arranged around the outer periphery of the stator core of the stator, and the inlet and outlet of the double-helix water-cooling channel are respectively connected to the cooling water circulation system of the hydropower station; the stator core laminations are evenly opened radially with air gap ventilation slots, and the slot openings of the air gap ventilation slots are connected to the gap between the stator and the rotor to form an air convection channel.

3. The high-efficiency heat dissipation system for a permanent magnet synchronous motor according to claim 2, characterized in that, The rotor heat dissipation module includes an annular flow channel and a magnetic field coil, wherein: The annular flow channel is formed inside the rotor shaft along the circumferential direction and is filled with magnetorheological fluid. The magnetic field coil is wound on a fixed bracket outside the rotor shaft. The two ends of the annular flow channel are connected to external heat dissipation fins to form a closed loop flow.

4. The high-efficiency heat dissipation system for a permanent magnet synchronous motor according to claim 3, characterized in that, The permanent magnet heat-conducting module includes heat dissipation holes and a heat-conducting filling layer, wherein: The permanent magnet has heat dissipation holes along its axial direction. The heat dissipation holes are filled with the thermally conductive filling layer. The two ends of the thermally conductive filling layer are in contact with the inner wall of the annular flow channel and the surface of the permanent magnet, respectively, forming a heat conduction path.

5. The high-efficiency heat dissipation system for a permanent magnet synchronous motor according to claim 4, characterized in that, The thermally conductive filler layer is made of graphene composite material.

6. The high-efficiency heat dissipation system for a permanent magnet synchronous motor according to claim 3, characterized in that, The temperature control unit includes a flow regulating valve and a magnetic field regulator, wherein: The flow regulating valve is located in the middle of the hydropower station's cooling water circulation system. It controls the cooling water circulation rate in the double-helix water-cooling channel by adjusting its own flow rate. The magnetic field regulator is electrically connected to the magnetic field coil and controls the flow rate of the magnetic fluid filling the annular flow channel by adjusting the magnetic field strength.

7. The high-efficiency heat dissipation system for a permanent magnet synchronous motor according to claim 6, characterized in that, The temperature control unit also includes a temperature sensor and a PLC controller, wherein: The number of temperature sensors is several, which are respectively attached to the winding end of the stator, the iron core surface of the rotor, and the surface of the permanent magnet, for real-time acquisition of the temperature of the stator, the rotor, and the permanent magnet; The PLC controller is used to receive temperature data sent by the temperature sensor, and output corresponding control signals based on the received temperature data to control the flow rate of the flow regulating valve and / or the magnetic field strength of the magnetic field regulator.

8. The high-efficiency heat dissipation system for a permanent magnet synchronous motor according to claim 7, characterized in that, The number of temperature sensors is at least 6, of which 2 temperature sensors are attached to the winding end of the stator and 2 temperature sensors are attached to the iron core surface of the rotor, and at least 2 temperature sensors are attached to the surface of the permanent magnet.

9. A high-efficiency heat dissipation method for a permanent magnet synchronous motor, applied to a high-efficiency heat dissipation system for a permanent magnet synchronous motor according to any one of claims 1-8, characterized in that, The heat dissipation method includes the following steps: When the motor is running, the heat generated by the stator copper loss is transferred to the stator core. The heat is released by the cooling water circulation outside the stator and the air gap ventilation, thus completing the heat dissipation of the stator area. Meanwhile, the heat generated by the rotor iron loss is transferred to the rotor shaft, and the heat from the eddy current loss of the permanent magnet is conducted to the rotor shaft through the thermally conductive material filled in the permanent magnet. When the rotor shaft rotates, the magnetic fluid filled in the rotor shaft circulates under the combined drive of centrifugal force and external magnetic field, and releases heat when the magnetic fluid flows through the external heat dissipation fins, thus completing the heat dissipation of the rotor and the permanent magnet area. During the heat dissipation process, the temperature data of the stator, the rotor and the permanent magnet are collected in real time, and corresponding control signals are output based on the collected temperature data to control the cooling water circulation rate in the stator region and / or the magnetohydrodynamic flow rate in the rotor region.

10. A high-efficiency heat dissipation method for a permanent magnet synchronous motor according to claim 9, characterized in that, The step of outputting corresponding control signals based on the collected temperature data to control the cooling water circulation rate in the stator region and / or the magnetohydrodynamic flow rate in the rotor region specifically includes: Temperature sensors are attached to the winding ends of the stator, the iron core surface of the rotor, and the surface of the permanent magnet, respectively. The temperature data of the stator, the rotor, and the permanent magnet are collected in real time through the temperature sensors, and the collected temperature data is transmitted to the PLC controller. After receiving the temperature data, the PLC controller compares the temperature data with the preset threshold of each region, and when the temperature data exceeds the preset threshold of the region, it outputs a corresponding control signal to the flow regulating valve and / or the magnetic field regulator. After receiving a control signal, the flow regulating valve controls the cooling water circulation rate in the double-helix water-cooling channel by adjusting its own flow rate; after receiving a control signal, the magnetic field regulator controls the flow rate of the magnetic fluid filled in the annular flow channel by adjusting the magnetic field strength.

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