A kind of auxiliary winding-based permanent magnet motor and temperature detection method

Abstract

The application discloses a kind of permanent magnet motor based on auxiliary winding and temperature detection method, permanent magnet motor includes rotor iron core, it is coaxially equipped with stator iron core in it, there is gap between rotor iron core and stator iron core;Permanent magnet rotor, along the circumferential setting of rotor iron core axle center;Stator yoke is set on stator iron core;Stator armature tooth is set in multiple along the outer wall of stator yoke, and each stator armature tooth is wound with armature winding;Stator modulation tooth is for one end open one end plugging structure, the plugging end of stator modulation tooth is connected at the end of stator armature tooth, and the open end of stator modulation tooth faces permanent magnet rotor;Magnetic barrier is set on stator modulation tooth;Stator auxiliary tooth is set in the open end of stator modulation tooth, and auxiliary winding is wound on the outside thereof, and stator auxiliary tooth is connected with stator modulation tooth by auxiliary magnetic bridge.The change of back electromotive force of auxiliary winding with permanent magnet temperature is monitored, and the permanent magnet temperature information can be indirectly and accurately obtained.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet motor technology, specifically relating to a permanent magnet motor based on an auxiliary winding and a temperature detection method. Background Technology

[0002] Permanent magnet motors, with their rotor using permanent magnets as the excitation magnetic field, interact with the stator armature winding magnetic field to generate torque output, have a wide range of applications due to their high power / torque density. However, high power / torque density motors face a series of severe thermal management challenges during operation.

[0003] On the one hand, high power / torque density typically requires a higher electrical load, i.e., increased winding current density, which inevitably leads to high copper losses. Simultaneously, the higher magnetic load increases spatial magnetic flux density, further increasing iron losses. These two factors combined result in a motor with high thermal load characteristics. On the other hand, permanent magnet motors have a compact structure, narrow heat transfer paths, high thermal resistance, and poor heat dissipation, further exacerbating the difficulty of thermal management. The interaction between high thermal load and poor heat dissipation conditions easily leads to heat accumulation inside the motor, causing uncontrolled temperature rise in the rotor permanent magnets, resulting in serious consequences such as permanent magnet demagnetization and motor burnout, severely impacting the motor's reliability and lifespan. Therefore, effective detection of permanent magnet temperature for precise thermal management is a crucial step in improving the reliability of permanent magnet motor systems.

[0004] Currently, various methods have been proposed for permanent magnet temperature detection, but all have certain limitations. The most common approach is to place wired or wireless temperature sensors on the rotor to directly obtain permanent magnet temperature information. However, wired sensors such as thermocouples require additional rotor leads, increasing the complexity and difficulty of motor structure layout. Wireless sensors such as infrared probes face the problems of high cost and susceptibility to interference from the complex electromagnetic environment inside the motor. In addition, some studies have calculated permanent magnet temperature by constructing motor loss models and thermal resistance network models and combining them with theoretical analysis, but this method is greatly affected by changes in motor parameters, and the calculation process is complex and has limited accuracy. Other studies have proposed to infer the remanence of the permanent magnet from the back electromotive force of the armature winding, and then infer the temperature. However, this method is affected by armature reaction, and the back electromotive force estimation has a large error, making it difficult to meet the requirements of temperature detection accuracy and reliability in practical applications.

[0005] In summary, existing methods for detecting the temperature of permanent magnets in permanent magnet motors have many shortcomings. There is an urgent need for a more accurate, simple, and low-cost method for detecting the temperature of permanent magnets to solve the current challenges in thermal management of permanent magnet motors and improve their performance and reliability. Summary of the Invention

[0006] The purpose of this invention is to provide a permanent magnet motor based on an auxiliary winding and a temperature detection method, so as to solve the technical defect in the prior art that it is impossible to accurately measure the temperature of a permanent magnet motor.

[0007] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, a permanent magnet motor based on an auxiliary winding is provided, comprising: A rotor core, in which a stator core is coaxially arranged, and there is a gap between the rotor core and the stator core; The rotor permanent magnet is arranged along the circumference of the rotor core axis; The stator yoke is mounted on the stator core. Stator armature teeth are provided in multiple ways along the outer wall of the stator yoke, and each stator armature tooth is wound with an armature winding. The stator modulation tooth has an open end and a closed end structure. The closed end of the stator modulation tooth is connected to the end of the stator armature tooth, and the open end of the stator modulation tooth faces the rotor permanent magnet. Magnetic barriers are installed on the stator modulation teeth; A stator auxiliary tooth is disposed in the open end of the stator modulation tooth, and an auxiliary winding is wound around its outer side. The stator auxiliary tooth and the stator modulation tooth are connected by an auxiliary magnetic bridge.

[0008] Furthermore, a stator slot is formed between two adjacent stator armature teeth, and the armature winding is disposed in the stator slot.

[0009] Furthermore, the magnetic barrier is a rectangular or concave structure and is disposed on the open end of the stator modulation tooth.

[0010] Furthermore, the rotor permanent magnets are radially magnetized, with adjacent rotor permanent magnets having opposite polarities, and rotor permanent magnets spaced apart having the same polarity.

[0011] Secondly, a temperature detection method for the aforementioned permanent magnet motor based on auxiliary windings is provided, comprising: The relationship between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor is obtained by theoretical calculation or no-load test method. After obtaining the relational expression, during the operation of the motor under load, the back EMF and mechanical speed signals of the auxiliary winding of the permanent magnet motor are acquired, and the back EMF coefficient of the auxiliary winding is calculated. Based on the relationship between the back EMF coefficient of the auxiliary winding and the temperature of the permanent magnet, and the back EMF coefficient of the auxiliary winding calculated during the motor load operation, the temperature of the permanent magnet of the permanent magnet motor under the load operation condition is calculated.

[0012] Furthermore, the expression for obtaining the relationship between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor specifically includes: While placing the permanent magnet motor in a constant temperature environment, a prime mover, torque sensor, armature winding connection wire and auxiliary winding connection wire are installed on the permanent magnet motor, and the prime mover, torque sensor, armature winding connection wire and auxiliary winding connection wire are located outside the constant temperature environment. Connect one end of the armature winding connecting wire to the controller and the other end to the armature winding in the permanent magnet motor; connect one end of the auxiliary winding connecting wire to the auxiliary winding in the permanent magnet motor and the other end to the controller through the voltage measurement module. Using the constant temperature environment, the back EMF coefficient of the auxiliary winding in the permanent magnet motor is obtained at different temperatures. The discrete back EMF coefficient and the permanent magnet temperature data are then fitted into a relationship expression between the back EMF coefficient of the auxiliary winding and the permanent magnet temperature of the permanent magnet motor using the least squares method.

[0013] Furthermore, obtaining the expression relating the back EMF coefficient of the auxiliary winding of the permanent magnet motor to the temperature of the permanent magnet motor also includes: Obtain permanent magnet motor parameters; Based on the obtained parameters, an expression for the change of remanence of the permanent magnet with temperature is established; Based on the acquired parameters and the expression for the change of residual magnetism of the permanent magnet with temperature, an expression for the back EMF coefficient of the auxiliary winding in the permanent magnet motor and the temperature of the permanent magnet are established.

[0014] Furthermore, during the operation of the motor under load, the back EMF and mechanical speed signals of the auxiliary winding of the permanent magnet motor are acquired, specifically including: The voltage measurement module is used to obtain the terminal voltage of the auxiliary winding in the permanent magnet motor; The rotational speed of the permanent magnet motor is obtained using a speed sensor.

[0015] Furthermore, the permanent magnet motor is a split-tooth vernier permanent magnet motor.

[0016] Furthermore, the test temperature range for the no-load test is -40℃ to 150℃.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The permanent magnet motor based on the auxiliary winding provided in this solution can indirectly and accurately obtain the temperature information of the permanent magnet by monitoring the change of the back EMF of the auxiliary winding with the temperature of the permanent magnet, thus avoiding many problems caused by installing traditional temperature sensors on the rotor.

[0018] 2. The stator slots provide good positioning and fixation for the armature windings, making the windings more regularly distributed in space.

[0019] 3. The setting of magnetic barriers greatly reduces the magnetic field coupling between the auxiliary winding and the armature winding, which greatly weakens the influence of the armature reaction on the back EMF of the auxiliary winding during normal operation, so that the back EMF of the auxiliary winding during normal operation of the motor is basically the same as that of the auxiliary winding when the motor is unloaded.

[0020] 4. The radial magnetization method distributes the magnetic field of the permanent magnets along the rotor radius, and the adjacent permanent magnets are arranged with opposite polarities, which enables the formation of a continuous and alternating magnetic field in the air gap, reducing magnetic field distortion. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic cross-sectional view of a permanent magnet motor based on an auxiliary winding provided by the present invention; Figure 2 A schematic diagram of the stator auxiliary tooth structure in a permanent magnet motor based on auxiliary windings provided by the present invention; Figure 3 A three-dimensional schematic diagram of the stator auxiliary teeth in a permanent magnet motor based on auxiliary windings provided by the present invention; Figure 4 A schematic diagram of the no-load test platform for a permanent magnet motor based on auxiliary windings provided by the present invention; Figure 5 A schematic diagram of the steps of the permanent magnet motor temperature detection method based on auxiliary winding provided by the present invention; Figure 6 The back EMF waveform of the auxiliary winding of the permanent magnet motor in the temperature detection method of the permanent magnet motor based on the auxiliary winding provided by the present invention.

[0023] The components are: 1. Rotor core; 2. Rotor permanent magnet; 3. Stator core; 4. Stator yoke; 5. Armature winding; 6. Stator armature teeth; 7. Stator modulation teeth; 8. Magnetic barrier; 9. Stator auxiliary teeth; 10. Auxiliary winding; 11. Auxiliary magnetic bridge; 12. Constant temperature chamber; 13. Permanent magnet motor; 14. Permanent magnet motor shaft; 15. Torque sensor; 16. Prime mover; 17. Prime mover shaft; 18. Torque sensor signal measurement module; 19. Armature winding connection wire; 20. Motor controller; 21. Power supply; 22. Voltage measurement module; 23. Auxiliary winding connection wire. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0030] To address the technical deficiencies mentioned in the background section, this embodiment provides a permanent magnet motor based on an auxiliary winding and a temperature detection method therein. The invention will be further described in detail below with reference to the accompanying drawings: In a first aspect, embodiments of the present invention provide a permanent magnet motor based on an auxiliary winding, such as... Figures 1-3 As shown, the motor is a split-tooth vernier permanent magnet motor, including a rotor core 1, with a stator core 3 coaxially arranged inside it, and a gap between the rotor core 1 and the stator core 3; a rotor permanent magnet 2, arranged along the circumference of the rotor core 1; a stator yoke 4, arranged on the stator core 3; multiple stator armature teeth 6 arranged along the outer wall of the stator yoke 4, each stator armature tooth 6 having an armature winding 5 wound on it; a stator modulation tooth 7, which is a structure with one end open and the other end closed, with the closed end of the stator modulation tooth 7 connected to the end of the stator armature 6 tooth, and the open end of the stator modulation tooth 7 facing the rotor permanent magnet 2; a magnetic barrier 8, arranged on the stator modulation tooth 7; and a stator auxiliary tooth 9, arranged in the open end of the stator modulation tooth 6, with an auxiliary winding 10 wound on its outer side, and the stator auxiliary tooth 9 and the stator modulation tooth 6 connected by an auxiliary magnetic bridge 11.

[0031] In the aforementioned permanent magnet motor, the auxiliary winding 10 wound around the outside of the stator auxiliary teeth 9 provides a new way to detect the temperature of the rotor permanent magnet 2. By monitoring the change of the back electromotive force of the auxiliary winding 10 with the temperature of the rotor permanent magnet 2, it can indirectly and accurately obtain the temperature information of the rotor permanent magnet 2. This non-contact detection method avoids many problems caused by installing traditional temperature sensors on the rotor, and improves the reliability and accuracy of temperature detection. Furthermore, the auxiliary winding 10 can continuously reflect the temperature change of the rotor permanent magnet 2 in real time, and can detect abnormal temperature conditions in a timely manner, which helps to take measures for thermal management in advance and ensure the safe and stable operation of the motor.

[0032] The stator modulation tooth 7 adopts a structure with one end open and the other end sealed. The sealed end is connected to the end of the stator armature tooth 6, and the open end faces the rotor permanent magnet 2. This allows for modulation of the magnetic field generated by the rotor permanent magnet 2, resulting in a more reasonable magnetic field distribution, increasing the harmonic content of the air gap magnetic field, enhancing the motor's torque output capability, and thus improving the motor's power density and efficiency. Secondly, a stator auxiliary tooth 9 and an auxiliary winding 10 are set in the middle of the end of the stator armature tooth 7, and a magnetic barrier is set between the stator auxiliary tooth 9 and the stator armature tooth 6 near the stator yoke 4. 8. This method greatly reduces the magnetic field coupling between the auxiliary winding 10 and the armature winding 5, significantly weakening the influence of the armature reaction on the back EMF of the auxiliary winding 10 during normal operation. As a result, the back EMF of the auxiliary winding 10 during normal operation is basically the same as that of the auxiliary winding 10 during no-load operation. Therefore, the temperature of the permanent magnet can be characterized by the back EMF coefficient without the need for complex steps such as additional calculation of the influence of the magnetic flux of the armature winding 5. At the same time, this method is less affected by changes in the parameters of the motor armature winding 5 and has high stability in multi-condition measurement.

[0033] In this embodiment, a stator slot is formed between two adjacent stator armature teeth 6, and the armature winding 5 is disposed in the stator slot; the stator slot provides a regular and relatively enclosed space for the armature winding 5, so that the armature winding 5 can be arranged relatively closely in it.

[0034] In addition, the stator slots provide good positioning and fixation for the armature winding 5, making the armature winding 5 more regularly distributed in space, which helps to generate a more uniform and symmetrical magnetic field and reduce magnetic field distortion and harmonic content.

[0035] Furthermore, the magnetic barrier 8 is a rectangular or concave structure and is set on the open end of the stator modulation tooth 6; wherein, the rectangular or concave magnetic barrier 8 can form a clear magnetic flux path restriction at the open end of the stator modulation tooth 6, which can guide the magnetic flux to flow in a predetermined direction and avoid the coupling of the armature magnetic field with the auxiliary winding.

[0036] In this design, the rotor permanent magnet 2 is radially magnetized, with adjacent rotor permanent magnets 2 having opposite polarities, while those spaced apart have the same polarity. This radial magnetization method ensures that the magnetic field of the rotor permanent magnets 2 is distributed along the rotor radius. The opposite polarity arrangement of adjacent rotor permanent magnets 2 allows for the formation of a continuous and alternating magnetic field in the air gap, contributing to a relatively uniform and symmetrical air gap magnetic field and reducing magnetic field distortion.

[0037] Secondly, a method for temperature detection of a permanent magnet motor based on an auxiliary winding is provided. This method is applied to the aforementioned permanent magnet motor, such as... Figure 5 As shown, it includes: S101. Obtain the relationship expression between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor through theoretical calculation or no-load test methods; for example, the specific process of obtaining the relationship expression through no-load test methods is as follows: Figure 4 As shown, a test fixture is first constructed, which includes a constant temperature chamber 12, with a support frame fixed inside the chamber 12 to support the permanent magnet motor; a prime mover 16, connected to the permanent magnet motor 13 via a coupling; a torque sensor 15, mounted on the coupling, with one end abutting against the permanent magnet motor 13 and the other end abutting against the prime mover 16, and the torque sensor 15 connected to the controller signal via a torque sensor signal measurement module 18; an armature winding 5 connecting wire, one end of which is connected to the controller, and the other end of which extends into the constant temperature chamber 12 to connect with the armature winding 5 in the permanent magnet motor 13; and an auxiliary winding connecting wire 23, one end of which extends into the constant temperature chamber 12 to connect with the auxiliary winding 10 in the permanent magnet motor 13, and the other end of which is connected to the controller via a voltage measurement module 22.

[0038] In this test fixture, a mounting hole is provided on one side of the constant temperature chamber 12, and a sealing ring is fixed in the mounting hole. The permanent magnet motor shaft 14 extends outward through the sealing ring. A coupling bracket is installed at the bottom of the coupling to support the coupling. One end of the coupling is connected to the permanent magnet motor shaft 14, and the other end is connected to the prime mover shaft 17. Subsequently, a torque sensor 15 is installed on the top of the coupling. One end of the torque sensor 15 abuts against the permanent magnet motor shaft 14, and the other end abuts against the prime mover shaft 17. The controller is a motor controller 20, which is connected to a power supply 21.

[0039] The auxiliary winding 10 is connected to the voltage measurement module 22 and the motor controller 20 via the auxiliary winding connection line 23. The temperature of the rotor permanent magnet 2 is indirectly measured by utilizing the electromagnetic induction relationship between the back electromotive force of the auxiliary winding 10 and the magnetic field of the rotor permanent magnet 2. The voltage measurement module 22 continuously and in real time collects the voltage signal of the auxiliary winding 10 and transmits it to the motor controller 20. The motor controller 20 can quickly and accurately calculate the real-time temperature of the rotor permanent magnet 2 according to the preset algorithm and model, and promptly detect abnormal temperature conditions. The torque sensor signal measurement module 18 is connected to the motor controller 20, which can measure the output torque of the permanent magnet motor 13 in real time. Combined with the temperature information measured by the auxiliary winding 10, the operating performance of the permanent magnet motor 13 under different temperature conditions can be comprehensively evaluated.

[0040] The specific experimental method steps are as follows: While placing the permanent magnet motor 13 in the constant temperature chamber 12, a prime mover 16, a torque sensor 15, an armature winding connection wire 19, and an auxiliary winding connection wire 23 are installed on the permanent magnet motor 13, with the prime mover 16, torque sensor 15, armature winding connection wire 19, and auxiliary winding connection wire 23 located outside the constant temperature chamber 12. Then, one end of the armature winding connection wire 19 is connected to the controller, and the other end is connected to the armature winding 5 in the permanent magnet motor 13. One end of the auxiliary winding connection wire 23 is connected to the auxiliary winding 10 in the permanent magnet motor 13, and the other end is connected to the controller through the voltage measurement module 22. Next, using the constant temperature chamber 12, the back EMF coefficient of the auxiliary winding 10 in the permanent magnet motor at different temperatures is obtained, and... The discrete back EMF coefficient and permanent magnet temperature data are fitted using the least squares method to form a relationship expression between the back EMF coefficient of the auxiliary winding 10 of the permanent magnet motor and the temperature of the permanent magnet motor. Specifically, the temperature of the constant temperature chamber 12 is controlled from -40℃ initially, maintained at -40℃ for more than one hour, and then the motor controller 20 is kept disconnected from the power supply 21. The prime mover 16 drives the permanent magnet motor 13 to run at its synchronous speed. The voltage measurement module 22 measures the terminal voltage signal of the auxiliary winding 10, which is used as the back EMF of the auxiliary winding at -40℃. Based on the obtained back EMF value at -40℃ and the speed signal obtained from the torque sensor signal measurement module 18, the back EMF coefficient is calculated using the formula: (1) k e This refers to the back EMF coefficient of the auxiliary winding of the permanent magnet motor. E 0 represents the back EMF of the auxiliary winding. n This refers to the mechanical rotation speed.

[0041] The back EMF coefficient of the auxiliary winding is calculated. Next, based on -40℃, the temperature is increased by 10℃ to -30℃, and the steps are repeated (using the prime mover 16 to drive the permanent magnet motor 13 at its synchronous speed, and using the voltage measurement module 22 to measure the terminal voltage signal of the auxiliary winding 10) to obtain the back EMF coefficient of the auxiliary winding at -30℃. Then, the temperature is increased by 10℃ sequentially to obtain the back EMF coefficient of the auxiliary winding at -20℃, -10℃, ..., 140℃, and 150℃. Finally, based on the obtained back EMF coefficients of the auxiliary winding at each temperature, the discrete back EMF coefficients of the auxiliary winding are fitted with the permanent magnet temperature data using mathematical fitting methods such as the least squares method to form a relational expression between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet motor.

[0042] In addition to obtaining the relational expression through the above-mentioned no-load test method, it can also be obtained using theoretical calculation methods; the theoretical calculation method includes the following steps: Step 1: Obtain motor parameters, including the permanent magnet at room temperature. T Residual magnetism at 0°C, residual magnetism temperature coefficient of permanent magnet, winding coefficient of auxiliary winding, number of turns of auxiliary winding, number of pole pairs of auxiliary winding, average cross-sectional area per pole of rotor permanent magnet, leakage flux coefficient, etc.

[0043] Step 2: Based on the motor parameters obtained in Step 1, establish the expression for the remanence of the permanent magnet: (2) B r ( T The temperature of the permanent magnet is T Residual magnetism at that time B r ( T 0) represents the temperature of the permanent magnet. T Residual magnetism at 0, T 0 represents room temperature. α is the remanence temperature coefficient of a permanent magnet.

[0044] Step 3: Based on the motor parameters obtained in Step 1 and the permanent magnet remanence expression established in Step 2, the back EMF expression for the auxiliary winding is established as follows: (3) E 0 represents the back EMF of the auxiliary winding. k w For winding coefficients, N s The number of turns in series per phase. f Auxiliary winding electrical frequency, A m This represents the average cross-sectional area of ​​a single pole of a permanent magnet. k f is the leakage flux coefficient.

[0045] Step 4: Based on the back EMF expression for the auxiliary winding established in Step 3 and formula (1), calculate the relationship between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor: (4) p For the number of pole pairs of the auxiliary winding; where, k e This refers to the back EMF coefficient of the auxiliary winding of the permanent magnet motor. E 0 represents the back EMF of the auxiliary winding. k w For winding coefficients, N s The number of turns in series per phase. A m This represents the average cross-sectional area of ​​a single pole of a permanent magnet.k f The leakage coefficient is... B r ( T The temperature of the permanent magnet is T Residual magnetism at that time B r ( T 0) represents the temperature of the permanent magnet. T Residual magnetism at 0, T 0 represents room temperature. α The remanence temperature coefficient of a permanent magnet. f Auxiliary winding electrical frequency, p To increase the number of pole pairs in the auxiliary winding, n This refers to the mechanical rotation speed.

[0046] As can be seen from formula (4), when the temperature of the permanent magnet changes, its remanence will change accordingly, which will lead to a change in the back EMF of the auxiliary winding, and ultimately a change in the back EMF coefficient of the auxiliary winding. Therefore, the relationship between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet motor can be theoretically calculated, providing an electrical characterization quantity for monitoring the temperature of the permanent magnet.

[0047] S102. After obtaining the relational expression, during the operation of the motor under load, the back EMF and mechanical speed signals of the auxiliary winding of the permanent magnet motor are acquired, and the back EMF coefficient of the auxiliary winding is calculated. For example, during the operation of the permanent magnet motor under load, the terminal voltage and mechanical speed signals of the auxiliary winding of the permanent magnet motor are acquired using another voltage measurement module and speed sensor. Specifically, the voltage measurement module 23 is used to acquire the terminal voltage of the auxiliary winding in the permanent magnet motor, and the speed sensor is used to acquire the speed of the permanent magnet motor.

[0048] Since the auxiliary winding has virtually no coupling with the armature winding and is not connected to a power source, the terminal voltage of the auxiliary winding can be considered as its back EMF. The back EMF coefficient of the auxiliary winding is calculated using the motor controller or other independent calculation modules.

[0049] S103. Based on the relationship expression between the back EMF coefficient of the auxiliary winding and the temperature of the permanent magnet, and the back EMF coefficient of the auxiliary winding calculated during the motor load operation, the temperature of the permanent magnet of the permanent magnet motor under the load operation condition is calculated.

[0050] like Figure 6 The figure shows the back EMF waveform of the auxiliary winding of the split-tooth vernier permanent magnet motor according to an embodiment of the present invention. In this embodiment, the split-tooth vernier permanent magnet motor uses a high-temperature resistant neodymium iron boron permanent magnet.

[0051] When the temperature rises from 25℃ to 130℃, the effective value of the back EMF of the auxiliary winding decreases from 1.20V to 1.10V, which reflects the relationship between the back EMF of the auxiliary winding and the temperature of the permanent magnet.

[0052] Furthermore, under 25°C operating conditions, the effective value of the back EMF of the auxiliary winding in the no-load state (without load connected to the shaft and the armature winding not connected to the power supply) of the permanent magnet motor is basically equal to that in the load state (with load connected to the shaft and the armature winding connected to the power supply). This demonstrates the characteristic that there is essentially no coupling between the armature winding magnetic field and the auxiliary winding of the aforementioned structure.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the invention, but these changes, modifications or equivalent substitutions are all within the scope of protection of the pending claims of the invention.

Claims

1. A permanent magnet motor based on an auxiliary winding, characterized in that, include: A rotor core, in which a stator core is coaxially arranged, and there is a gap between the rotor core and the stator core; The rotor permanent magnet is arranged along the circumference of the rotor core axis; The stator yoke is mounted on the stator core. Stator armature teeth are provided in multiple ways along the outer wall of the stator yoke, and each stator armature tooth is wound with an armature winding. The stator modulation tooth has an open end and a closed end structure. The closed end of the stator modulation tooth is connected to the end of the stator armature tooth, and the open end of the stator modulation tooth faces the rotor permanent magnet. Magnetic barriers are installed on the stator modulation teeth; A stator auxiliary tooth is disposed in the open end of the stator modulation tooth, and an auxiliary winding is wound around its outer side. The stator auxiliary tooth and the stator modulation tooth are connected by an auxiliary magnetic bridge.

2. The permanent magnet motor based on auxiliary winding according to claim 1, characterized in that, A stator slot is formed between two adjacent stator armature teeth, and the armature winding is disposed in the stator slot.

3. The permanent magnet motor based on auxiliary winding according to claim 1, characterized in that, The magnetic barrier is a rectangular or concave structure and is located on the open end of the stator modulation tooth.

4. The permanent magnet motor based on auxiliary winding according to claim 1, characterized in that, The rotor permanent magnets are radially magnetized, with adjacent rotor permanent magnets having opposite polarities, and rotor permanent magnets spaced apart having the same polarity.

5. A temperature detection method for a permanent magnet motor based on an auxiliary winding as described in any one of claims 1-4, characterized in that, include: The relationship between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor is obtained by theoretical calculation or no-load test method. After obtaining the relational expression, during the operation of the motor under load, the back EMF and mechanical speed signals of the auxiliary winding of the permanent magnet motor are acquired, and the back EMF coefficient of the auxiliary winding is calculated. Based on the relationship between the back EMF coefficient of the auxiliary winding and the temperature of the permanent magnet, and the back EMF coefficient of the auxiliary winding calculated during the motor load operation, the temperature of the permanent magnet of the permanent magnet motor under the load operation condition is calculated.

6. The method for detecting the temperature of a permanent magnet motor according to claim 5, characterized in that, The expression for obtaining the relationship between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor specifically includes: While placing the permanent magnet motor in a constant temperature environment, a prime mover, torque sensor, armature winding connection wire and auxiliary winding connection wire are installed on the permanent magnet motor, and the prime mover, torque sensor, armature winding connection wire and auxiliary winding connection wire are located outside the constant temperature environment. Connect one end of the armature winding connecting wire to the controller and the other end to the armature winding in the permanent magnet motor; connect one end of the auxiliary winding connecting wire to the auxiliary winding in the permanent magnet motor and the other end to the controller through the voltage measurement module. Using the constant temperature environment, the back EMF coefficient of the auxiliary winding in the permanent magnet motor is obtained at different temperatures. The discrete back EMF coefficient and the permanent magnet temperature data are then fitted into a relationship expression between the back EMF coefficient of the auxiliary winding and the permanent magnet temperature of the permanent magnet motor using the least squares method.

7. The method for detecting the temperature of a permanent magnet motor according to claim 5, characterized in that, The expression for obtaining the relationship between the back EMF coefficient of the auxiliary winding of a permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor also includes: Obtain permanent magnet motor parameters; Based on the obtained parameters, an expression for the change of remanence of the permanent magnet with temperature is established; Based on the acquired parameters and the expression for the change of residual magnetism of the permanent magnet with temperature, an expression for the back EMF coefficient of the auxiliary winding in the permanent magnet motor and the temperature of the permanent magnet are established.

8. The method for detecting the temperature of a permanent magnet motor according to claim 5, characterized in that, During motor load operation, the back EMF and mechanical speed signals of the auxiliary winding of the permanent magnet motor are acquired, specifically including: The voltage measurement module is used to obtain the terminal voltage of the auxiliary winding in the permanent magnet motor; The rotational speed of the permanent magnet motor is obtained using a speed sensor.

9. The method for detecting the temperature of a permanent magnet motor according to claim 5, characterized in that, The permanent magnet motor is a split-tooth vernier permanent magnet motor.

10. The method for detecting the temperature of a permanent magnet motor according to claim 5, characterized in that, The test temperature range for the no-load test is -40℃ to 150℃.

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