Permanent magnet motor based on auxiliary winding and temperature detection method

Abstract

The invention discloses a permanent magnet motor based on an auxiliary winding and a temperature detection method, the permanent magnet motor comprises a rotor iron core, a stator iron core is coaxially arranged in the rotor iron core, and a gap is arranged between the rotor iron core and the stator iron core; the rotor permanent magnets are circumferentially arranged along the axis of the rotor iron core; a stator yoke disposed on the stator core; the plurality of stator armature teeth are arranged along the outer wall of the stator yoke, and an armature winding is wound on each stator armature tooth; the stator modulation teeth are of a structure with one open end and one blocked end, the blocked ends of the stator modulation teeth are connected to the end parts of the stator armature teeth, and the open ends of the stator modulation teeth face the rotor permanent magnets; the magnetic barriers are arranged on the stator modulation teeth; and the stator auxiliary teeth are arranged in the open ends of the stator modulation teeth, auxiliary windings are wound on the outer sides of the stator auxiliary teeth, and the stator auxiliary teeth are connected with the stator modulation teeth through auxiliary magnetic bridges. By monitoring the change of the counter electromotive force of the auxiliary winding along with the temperature of the permanent magnet, the temperature information of the permanent magnet can be indirectly and accurately obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of permanent magnet motors, and in particular relates to a permanent magnet motor based on an auxiliary winding and a temperature detection method. Background Art

[0002] Permanent magnet motors (PMMs), with their rotors using permanent magnets as the excitation field, interact with the stator armature winding's magnetic field to generate torque, offer high power / torque density and are widely used in numerous fields. However, these 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, which increases the winding current density, inevitably leading to high copper loss. Simultaneously, the higher magnetic load increases the spatial flux density, which in turn increases iron loss. These two factors combine to create a high thermal load characteristic for the motor. Furthermore, the compact structure of permanent magnet motors (PMMs), with narrow heat transfer paths, high thermal resistance, and poor heat dissipation, further exacerbate the difficulty of thermal management. The interaction of high thermal load and poor heat dissipation can easily lead to heat accumulation within the motor, causing uncontrolled temperature rise in the rotor's permanent magnets, leading to serious consequences such as permanent magnet demagnetization and motor burnout, severely impacting the motor's reliability and service life. Therefore, effective monitoring of PM temperature for precise thermal management is crucial for improving the reliability of PM motor systems.

[0004] At present, the industry has proposed a variety of methods to detect the temperature of permanent magnets, but all of them have certain limitations. The most common method is to place wired or wireless temperature sensors on the rotor to directly obtain the permanent magnet temperature information; however, wired sensors such as thermocouples require additional rotor lead wires, which increases 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 calculate the permanent magnet temperature by constructing a motor loss model and a thermal resistance network model, and combining them with theoretical analysis, but this method is greatly affected by changes in motor parameters, the calculation process is complex and the accuracy is limited; other studies have proposed to infer the permanent magnet remanence and then the temperature by the back EMF of the armature winding, but this method is affected by the armature reaction, and the back EMF estimation has a large error, which is difficult to meet the requirements of temperature detection accuracy and reliability in practical applications.

[0005] In summary, the existing permanent magnet temperature detection method of permanent magnet motors has many shortcomings. There is an urgent need for a more accurate, simple and low-cost permanent magnet temperature detection method to solve the current problems faced by permanent magnet motors in thermal management and improve the performance and reliability of permanent magnet motors. Summary of the Invention

[0006] The object of the present invention is to provide a permanent magnet motor and a temperature detection method based on an auxiliary winding, so as to solve the technical defect in the prior art that the temperature of the permanent magnet motor cannot be accurately measured.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, a permanent magnet motor based on an auxiliary winding is provided, comprising: A rotor core, wherein a stator core is coaxially arranged inside the rotor core, with a gap between the rotor core and the stator core; The rotor permanent magnet is arranged along the circumference of the rotor core axis; A stator yoke is provided on the stator core; A plurality of stator armature teeth are provided along the outer wall of the stator yoke, and an armature winding is wound around each of the stator armature teeth; The stator modulating tooth is a structure with one end open and the other end closed, wherein the closed end of the stator modulating tooth is connected to the end of the stator armature tooth, and the open end of the stator modulating tooth faces the rotor permanent magnet; A magnetic barrier is provided on the stator modulation teeth; The stator auxiliary teeth are arranged in the open ends of the stator modulation teeth, and auxiliary windings are wound around the outer sides of the stator auxiliary teeth. The stator auxiliary teeth are connected to the stator modulation teeth through an auxiliary magnetic bridge.

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

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

[0010] Furthermore, the rotor permanent magnets are radially magnetized, the polarities of two adjacent rotor permanent magnets are opposite, and the polarities of the rotor permanent magnets spaced apart from each other are the same.

[0011] In a second aspect, a temperature detection method for the above-mentioned permanent magnet motor based on auxiliary winding is provided, comprising: Obtaining, by theoretical calculation or no-load test, an expression for the relationship between the back-electromotive force coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor; After obtaining the relational expression, during the motor load operation, the back electromotive force and the mechanical speed signal of the auxiliary winding of the permanent magnet motor are obtained, and the back electromotive force coefficient of the auxiliary winding is calculated; The temperature of the permanent magnet of the permanent magnet motor under the load operation condition is calculated based on the relationship expression between the back electromotive force coefficient of the auxiliary winding and the permanent magnet temperature and the back electromotive force coefficient of the auxiliary winding calculated during the motor load operation.

[0012] Furthermore, the expression for obtaining the relationship between the back electromotive force 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, installing a prime mover, a torque sensor, an armature winding connection line, and an auxiliary winding connection line on the permanent magnet motor, and making the prime mover, the torque sensor, the armature winding connection line, and the auxiliary winding connection line be 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; The constant temperature environment is used to obtain the back-electromotive force coefficient of the auxiliary winding in the permanent magnet motor at different temperatures, and the discrete back-electromotive force coefficient and permanent magnet temperature data are fitted into a relationship expression of the back-electromotive force coefficient of the auxiliary winding of the permanent magnet motor and the permanent magnet temperature of the permanent magnet motor through the least squares method.

[0013] Furthermore, obtaining an expression for the relationship between the back electromotive force coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor also includes: Get permanent magnet motor parameters; Establishing an expression for the change of the remanence of the permanent magnet with temperature based on the obtained parameters; Based on the acquired parameters and the expression of the change of the permanent magnet remanence with temperature, an expression of the back electromotive force coefficient of the auxiliary winding in the permanent magnet motor and the permanent magnet temperature is established.

[0014] Furthermore, during the motor load operation, the back electromotive force and mechanical speed signal of the auxiliary winding of the permanent magnet motor are obtained, specifically including: A voltage measurement module is used to obtain the terminal voltage of the auxiliary winding in the permanent magnet motor; A speed sensor is used to obtain the speed of the permanent magnet motor.

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

[0016] Furthermore, the test temperature range of the no-load test is -40°C to 150°C.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This solution provides an auxiliary winding-based permanent magnet motor. By monitoring the changes in the auxiliary winding back EMF as the permanent magnet temperature changes, the permanent magnet temperature information can be indirectly and accurately obtained, avoiding many problems caused by installing traditional temperature sensors on the rotor.

[0018] 2. The stator slots play a good role in positioning and fixing the armature winding, making the distribution of the winding in space more regular.

[0019] 3. The setting of the magnetic barrier greatly reduces the magnetic field coupling between the auxiliary winding and the armature winding, and greatly weakens the influence of the armature reaction during normal operation on the back EMF of the auxiliary winding, so that the back EMF of the auxiliary winding during normal operation of the motor is basically the same as the back EMF of the auxiliary winding when the motor is no-load.

[0020] 4. The radial magnetization method makes the magnetic field direction of the permanent magnet distributed along the radius of the rotor. The adjacent permanent magnets are arranged with opposite polarities, so that a continuous and alternating magnetic field can be formed in the air gap, reducing the magnetic field distortion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[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 teeth structure in the permanent magnet motor based on the auxiliary winding provided by the present invention; Figure 3 A three-dimensional schematic diagram of the stator auxiliary teeth in the permanent magnet motor based on the auxiliary winding provided by the present invention; Figure 4 Schematic diagram of a 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 the auxiliary winding provided by the present invention; Figure 6 This is the back electromotive force waveform of the auxiliary winding of the permanent magnet motor in the permanent magnet motor temperature detection method based on the auxiliary winding provided by the present invention.

[0023] Among them: 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 box; 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 line; 20. Motor controller; 21. Power supply; 22. Voltage measurement module; 23. Auxiliary winding connection line. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0027] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only 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 be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

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

[0031] In the above-mentioned 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, the temperature information of the rotor permanent magnet 2 can be indirectly and accurately obtained. 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. In addition, the auxiliary winding 10 can continuously and in real time reflect the temperature changes of the rotor permanent magnet 2, and can promptly detect temperature anomalies, 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 closed, and the closed end is connected to the end of the stator armature tooth 6, and the open end faces the rotor permanent magnet 2, which can modulate the magnetic field generated by the rotor permanent magnet 2, making the magnetic field distribution more reasonable, improving the air gap magnetic field harmonic content of the motor, and enhancing the torque output capacity of the motor, thereby improving the power density and efficiency of the motor; 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 side. 8. The magnetic field coupling between the auxiliary winding 10 and the armature winding 5 is greatly reduced, and the influence of the armature reaction during normal operation on the back EMF of the auxiliary winding 10 is greatly weakened. As a result, the back EMF of the auxiliary winding 10 during normal operation of the motor is basically the same as the back EMF of the auxiliary winding 10 when the motor is no-loaded. Therefore, the back EMF coefficient can be used to characterize the permanent magnet temperature 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-operating condition measurements.

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

[0034] In addition, the stator slots play a good role in positioning and fixing the armature winding 5, making the distribution of the armature winding 5 in space more regular, helping to generate a more uniform and symmetrical magnetic field, and reducing magnetic field distortion and harmonic content.

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

[0036] In this solution, the rotor permanent magnets 2 are radially magnetized. Adjacent rotor permanent magnets 2 have opposite polarity, while spaced-apart rotor permanent magnets 2 have the same polarity. This radial magnetization ensures that the magnetic field of the rotor permanent magnets 2 is distributed along the rotor radius. The arrangement of adjacent rotor permanent magnets 2 with opposite polarity creates 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] In the second aspect, a method for detecting the temperature of a permanent magnet motor based on an auxiliary winding is provided, and the method is applied to the above-mentioned permanent magnet motor, such as Figure 5 Shown, including: S101. Obtain a relationship expression between the back electromotive force coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor by a theoretical calculation method or a no-load test method. For example, the specific process of obtaining the relationship expression by the no-load test method is as follows: Figure 4 As shown, first, a test tool is built, which includes a constant temperature box 12, with a bracket fixed inside the constant temperature box 12, which is used to support the permanent magnet motor; a prime mover 16, which is connected to the permanent magnet motor 13 through a coupling; a torque sensor 15, which is arranged on the coupling, with one end abutting on the permanent magnet motor 13 and the other end abutting on the prime mover 16, and the torque sensor 15 is connected to the controller signal through the torque sensor signal measurement module 18; an armature winding 5 connecting line, one end of which is connected to the controller, and the other end is used to extend to the constant temperature box 12 and connect to the armature winding 5 in the permanent magnet motor 13; an auxiliary winding connecting line 23, one end of which is used to extend to the constant temperature box 12 and connect 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.

[0038] In this test fixture, a mounting hole is opened on one side of the constant temperature box 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, and the coupling bracket supports 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; then, a torque sensor 15 is installed on the top of the coupling, and one end of the torque sensor 15 abuts on the permanent magnet motor shaft 14, and the other end abuts on the prime mover shaft 17; the controller is a motor controller 20, and the motor controller 20 is connected to the power supply 21.

[0039] With the help of the auxiliary winding connecting line 23, the auxiliary winding 10 is connected to the voltage measurement module 22 and the motor controller 20, and the electromagnetic induction relationship between the back electromotive force of the auxiliary winding 10 and the magnetic field of the rotor permanent magnet 2 is used to indirectly measure the temperature 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 detect temperature abnormalities in time; through the torque sensor signal measurement module 18 connected to the motor controller 20, the output torque of the permanent magnet motor 13 can be measured 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 test method steps are as follows: While placing the permanent magnet motor 13 in the constant temperature box 12, the prime mover 16, the torque sensor 15, the armature winding connection line 19 and the auxiliary winding connection line 23 are installed on the permanent magnet motor 13, and the prime mover 16, the torque sensor 15, the armature winding connection line 19 and the auxiliary winding connection line 23 are located outside the constant temperature box 12; then one end of the armature winding connection line 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 line 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; secondly, the constant temperature box 12 is used to obtain the back electromotive force coefficient of the auxiliary winding 10 in the permanent magnet motor at different temperatures, and The discrete back-electromotive force coefficient and permanent magnet temperature data are fitted into an expression for the relationship between the back-electromotive force coefficient of the permanent magnet motor auxiliary winding 10 and the permanent magnet temperature of the permanent magnet motor by the least squares method; the specific operation is to control the temperature of the constant temperature box 12 to start from -40°C and maintain it at -40°C for more than one hour for subsequent operations, keep the motor controller 20 disconnected from the power supply 21, use the prime mover 16 to drive the permanent magnet motor 13 to run at its synchronous speed, use the voltage measurement module 22 to measure the terminal voltage signal of the auxiliary winding 10, and use it as the back-electromotive force of the auxiliary winding at -40°C; based on the back-electromotive force value obtained at -40°C and the speed signal obtained by the torque sensor signal measurement module 18, the back-electromotive force coefficient is calculated according to the formula: (1) k e is the back EMF coefficient of the auxiliary winding of the permanent magnet motor, E 0 is the auxiliary winding back EMF, n is the mechanical speed.

[0041] The back-EMF coefficient of the auxiliary winding is calculated. Next, based on -40°C, the temperature is increased by 10°C to -30°C, and the steps are repeated (using the prime mover 16 to drive the permanent magnet motor 13 to operate 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°C; then the temperature is increased by 10°C in sequence to obtain the back-EMF coefficients of the auxiliary winding at -20°C, -10°C, ..., 140°C, and 150°C; finally, based on the obtained back-EMF coefficients of the auxiliary winding at each temperature, the discrete back-EMF coefficients of the auxiliary winding and the permanent magnet temperature data are fitted into an expression for the relationship between the back-EMF coefficient of the auxiliary winding of the permanent magnet motor and the permanent magnet temperature of the permanent magnet motor through mathematical fitting methods such as the least squares method.

[0042] In addition to obtaining the relational expression through the above-mentioned no-load test method steps, a theoretical calculation method can also be used to obtain it; the theoretical calculation method includes the following steps: Step 1: Obtain motor parameters, including the permanent magnet at room temperature T Remanence at 0, remanence 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 magnetic coefficient, etc.

[0043] Step 2: Based on the motor parameters obtained in step 1, establish the permanent magnet remanence expression: (2) B r ( T ) is the permanent magnet temperature T The residual magnetism, B r ( T 0) is the permanent magnet temperature T Remanence at 0, T 0 is room temperature, α is the remanence temperature coefficient of the 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 of the auxiliary winding is established as follows: (3) E 0 is the auxiliary winding back EMF, k w is the winding coefficient, N s is the number of series turns per phase, f Auxiliary winding electrical frequency, A m is the average cross-sectional area of ​​a permanent magnet monopole, k f is the magnetic flux leakage coefficient.

[0045] Step 4: Based on the auxiliary winding back EMF expression 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 permanent magnet temperature of the permanent magnet motor: (4) p is the number of auxiliary winding pole pairs; where, k e is the back EMF coefficient of the auxiliary winding of the permanent magnet motor, E 0 is the auxiliary winding back EMF, k w is the winding coefficient, N s is the number of series turns per phase, A m is the average cross-sectional area of ​​a permanent magnet monopole,k f is the magnetic flux leakage coefficient, B r ( T ) is the permanent magnet temperature T The residual magnetism, B r ( T 0) is the permanent magnet temperature T Remanence at 0, T 0 is room temperature, α is the remanence temperature coefficient of the permanent magnet, f Auxiliary winding electrical frequency, p is the number of auxiliary winding pole pairs, n is the mechanical speed.

[0046] From formula (4), we can see that when the permanent magnet temperature changes, its remanence will change accordingly, which will lead to changes in the auxiliary winding back EMF, and ultimately lead to changes in the auxiliary winding back EMF coefficient. Therefore, the relationship between the back EMF coefficient of the auxiliary winding of the permanent magnet motor and the permanent magnet temperature of the permanent magnet motor can be theoretically calculated, providing an electrical characterization of the permanent magnet temperature that can be monitored.

[0047] S102. After obtaining the relational expression, during the load operation of the motor, the back EMF and mechanical speed signal of the auxiliary winding of the permanent magnet motor are obtained, and the back EMF coefficient of the auxiliary winding is calculated. Exemplarily, during the load operation of the permanent magnet motor, another voltage measurement module and a speed sensor are used to obtain the terminal voltage and mechanical speed signal of the auxiliary winding of the permanent magnet motor. Specifically, the voltage measurement module 23 is used to obtain the terminal voltage of the auxiliary winding in the permanent magnet motor; and the speed sensor is used to obtain the speed of the permanent magnet motor.

[0048] Because the auxiliary winding has little coupling with the armature winding and is not connected to a power source, the terminal voltage of the auxiliary winding can be considered its back EMF. The back EMF coefficient of the auxiliary winding is calculated using a motor controller or other independent calculation module.

[0049] S103 , calculating the temperature of the permanent magnet of the permanent magnet motor under the load operating condition according to the relationship expression between the back EMF coefficient of the auxiliary winding and the permanent magnet temperature and the back EMF coefficient of the auxiliary winding calculated during the motor load operation.

[0050] like Figure 6 As shown in FIG. 1 , the back electromotive force waveform of the auxiliary winding of the split-tooth vernier permanent magnet motor according to an embodiment of the present invention is shown. In this embodiment, the split-tooth vernier permanent magnet motor adopts high-temperature-resistant neodymium iron boron permanent magnets.

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

[0052] Furthermore, at 25°C, the auxiliary winding's back EMF was essentially equal in the no-load state (no load on the shaft and no power supply to the armature winding) and the loaded state (with a load on the shaft and a power supply to the armature winding). This demonstrates the absence of coupling between the armature winding's magnetic field and the auxiliary winding in this structure.

[0053] 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 its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art may still make various changes, modifications or equivalent substitutions to the specific implementation methods 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 auxiliary winding, characterized in that: include: A rotor core, wherein a stator core is coaxially arranged inside the rotor core, with a gap between the rotor core and the stator core; The rotor permanent magnet is arranged along the circumference of the rotor core axis; A stator yoke is provided on the stator core; A plurality of stator armature teeth are provided along the outer wall of the stator yoke, and an armature winding is wound around each of the stator armature teeth; The stator modulating tooth is a structure with one end open and the other end closed, wherein the closed end of the stator modulating tooth is connected to the end of the stator armature tooth, and the open end of the stator modulating tooth faces the rotor permanent magnet; A magnetic barrier is provided on the stator modulation teeth; The stator auxiliary teeth are arranged in the open ends of the stator modulation teeth, and auxiliary windings are wound around the outer sides of the stator auxiliary teeth. The stator auxiliary teeth are connected to the stator modulation teeth through 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 arranged 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 arranged 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, the polarities of two adjacent rotor permanent magnets are opposite, and the polarities of the rotor permanent magnets spaced apart from each other are the same.

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

6. The method for detecting temperature of a permanent magnet motor according to claim 5, wherein: The expression for obtaining the relationship between the back electromotive force 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, installing a prime mover, a torque sensor, an armature winding connection line, and an auxiliary winding connection line on the permanent magnet motor, and making the prime mover, the torque sensor, the armature winding connection line, and the auxiliary winding connection line be 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; The constant temperature environment is used to obtain the back-electromotive force coefficient of the auxiliary winding in the permanent magnet motor at different temperatures, and the discrete back-electromotive force coefficient and permanent magnet temperature data are fitted into a relationship expression of the back-electromotive force coefficient of the auxiliary winding of the permanent magnet motor and the permanent magnet temperature of the permanent magnet motor through the least squares method.

7. The method for detecting temperature of a permanent magnet motor according to claim 5, characterized in that: Obtaining the relationship expression between the back electromotive force coefficient of the auxiliary winding of the permanent magnet motor and the temperature of the permanent magnet of the permanent magnet motor, further comprising: Get permanent magnet motor parameters; Establishing an expression for the change of the remanence of the permanent magnet with temperature based on the obtained parameters; Based on the acquired parameters and the expression of the change of the permanent magnet remanence with temperature, an expression of the back electromotive force coefficient of the auxiliary winding in the permanent magnet motor and the permanent magnet temperature is established.

8. The method for detecting temperature of a permanent magnet motor according to claim 5, wherein: During the motor load operation, the back electromotive force and mechanical speed signal of the auxiliary winding of the permanent magnet motor are obtained, specifically including: A voltage measurement module is used to obtain the terminal voltage of the auxiliary winding in the permanent magnet motor; A speed sensor is used to obtain the speed of the permanent magnet motor.

9. The method for detecting temperature of a permanent magnet motor according to claim 5, wherein: The permanent magnet motor is a split-tooth vernier permanent magnet motor.

10. The method for detecting temperature of a permanent magnet motor according to claim 1, wherein: The test temperature range of the no-load test is -40°C to 150°C.

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