Rare-earth-free permanent magnet synchronous motor with noise reduction function

Abstract

The invention discloses a rare-earth-free permanent magnet synchronous motor with a noise reduction function, and relates to the technical field of synchronous motors, a motor shell is used as a main mounting foundation for mounting and positioning other components, and after equipment assembly is completed, the magnetic flux change of an air gap between a stator and a rotor is detected through a magnetic field detection device; according to the magnetic flux change of the air gap detected by the magnetic field detection device, the magnetic field detection device outputs a signal to make the adjusting device deflect, and the adjusting device deflects to make the magnetic fields between the adjusting device and the air gap counteract each other, so that the magnetic flux change of the air gap and the harmonic amplitude causing the magnetic flux change of the air gap are reduced; therefore, the harmonic magnetic field of the air gap cannot be combined with the current of the stator to generate noise, the adjusting position of the adjusting device is detected through the noise detection device, when the adjusting device deflects, the noise is gradually reduced, and when the noise is changed from small to large, the noise detection device feeds back an electric signal to adjust the adjusting device.

Description

Technical Field

[0001] The present invention relates to the technical field of synchronous motors, in particular to a rare earth-free permanent magnet synchronous motor with a noise reduction function. Background Art

[0002] Permanent magnet synchronous motors are widely used in industrial drives, new energy vehicles, smart homes and other fields due to their advantages of high efficiency and high power density.

[0003] The noise problem during motor operation has always been a pain point in the industry. Existing motor noise mainly comes from the harmonic fluctuations of the air gap magnetic field between the stator and rotor, mechanical structure vibration, etc. Among them, the electromagnetic noise generated by the interaction between the air gap harmonic magnetic field and the stator current is particularly prominent. Traditional noise reduction methods mostly use passive sound insulation or structural reinforcement. They lack the ability to detect and dynamically adjust the air gap magnetic field harmonics in real time, making it difficult to accurately offset harmonic interference, resulting in limited noise reduction effects; and some designs are not optimized for the air gap structure, further exacerbating the generation of noise sources. In addition, traditional adjustment devices have a delayed response and cannot be adjusted in real time according to changes in the magnetic field. They are prone to over- or under-adjustment, affecting the motor's operating stability and noise reduction efficiency. Summary of the Invention

[0004] The object of the present invention is to provide a rare earth-free permanent magnet synchronous motor with a noise reduction function to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions: A rare earth-free permanent magnet synchronous motor with a noise reduction function includes a motor housing, a stator, a rotor, a magnetic field detection device, an adjustment device and a noise detection device. The stator is placed in the motor housing, the rotor is placed in the stator, the magnetic field detection device is placed outside the stator, there are two adjustment devices, the two adjustment devices are respectively connected to the stator and the rotor, the noise detection device is placed in the motor housing, the noise detection device is tightly connected to the motor housing, the magnetic field detection device is electrically connected to the adjustment device, and the noise detection device is electrically connected to the magnetic field detection device.

[0006] The motor housing serves as the main installation base for the installation and positioning of other components. After the equipment is assembled, the magnetic field detection device is used to detect the magnetic flux change in the air gap between the stator and the rotor. Based on the magnetic flux change in the air gap detected by the magnetic field detection device, the magnetic field detection device outputs a signal to deflect the adjustment device. By deflecting the adjustment device, the magnetic fields between the adjustment device and the air gap cancel each other out, thereby reducing the magnetic flux change in the air gap and the harmonic amplitude causing the change in the air gap magnetic flux, so that the harmonic magnetic field of the air gap does not combine with the stator current to generate noise. The adjustment position of the adjustment device is detected by the noise detection device. When the adjustment device is deflected, the noise gradually decreases. The noise signal is detected by the noise detection device. When the noise increases from small to large, the noise detection device feeds back an electrical signal to adjust the adjustment device to prevent the adjustment position of the adjustment device from being adjusted too much, thereby reducing the effect of noise regulation.

[0007] Furthermore, the magnetic field detection device includes a first detection coil, a second detection coil and a processor, the first detection coil and the second detection coil are equal in size, the first detection coil and the second detection coil have the same number of turns, the first detection coil and the second detection coil have opposite rotation directions, the first detection coil and the second detection coil are connected by wires, the first detection coil and the processor are connected by wires, and the first detection coil and the second detection coil are symmetrically placed.

[0008] By setting a first detection coil and a second detection coil, and setting the first detection coil and the second detection coil to have the same number of turns and be wound in opposite directions and connected in series, the magnetic flux changes in the first detection coil and the second detection coil emitted by the stator itself are the same but in opposite directions, thereby eliminating the interference of the stator magnetic field changes detected by the first detection coil and the second detection coil, so that the first detection coil and the second detection coil can detect the magnetic flux changes in the air gap between the stator and the rotor. When the magnetic field amount in the air gap between the stator and the rotor changes, the change in magnetic flux causes the magnetic flux between the first detection coil and the second detection coil to change, and then the induced current generated by the first detection coil and the second detection coil is amplified by the processor.

[0009] Furthermore, the processor is used to process the electrical signals of the first detection coil and the second detection coil, and the processor is electrically connected to the adjustment device.

[0010] The electrical signals of the first detection coil and the second detection coil are processed by the processor, the electrical signals of the first detection coil and the second detection coil are amplified, and then the processor outputs the signal to the adjustment device, which offsets the harmonics of the air gap, thereby reducing noise.

[0011] Furthermore, an auxiliary magnet is provided in the stator gap, and the auxiliary magnet is ferrite.

[0012] By arranging auxiliary magnets between the stator gaps, the space of the air gap is reduced, the source of noise generated by the air gap is reduced, and thus the noise is reduced.

[0013] Furthermore, the adjustment device includes an adjustment ring, an adjustment plate, a first metal sheet and a second metal sheet. The adjustment ring is rotatably connected to the rotor. Several adjustment plates are provided on the adjustment ring. Several adjustment rings are rotatably connected to the adjustment plate. The first metal sheet is rotatably connected to the rotor. The first metal sheet is fastened to the second metal sheet on a side away from the rotor. The second metal sheet is fastened to the adjustment plate on a side away from the first metal sheet. The thermal expansion coefficient of the first metal sheet is greater than the thermal expansion coefficient of the second metal sheet. The processor is connected to the first metal sheet by wires.

[0014] The middle part of the second metal sheet is connected to the adjustment plate through a fixed plate. The adjustment plate is deflected at a certain angle when installed. When the first detection coil and the second detection coil detect the change of the magnetic flux of the air gap, the first metal sheet is energized through the processor. When the high-order harmonics emitted by the air gap magnetic field are detected, the magnetic flux changes greatly, and the induced current generated by the processor is large. The first metal sheet is energized by the processor so that the first metal sheet is heated and collided, causing the inside of the first metal sheet to concave. The concave inside of the first metal sheet drives the inside of the second metal sheet to concave, which drives the fixed plate to concave, thereby driving the adjustment plate to rotate. The magnetic field and the harmonic magnetic field emitted by the adjustment plate are offset by the rotation of the adjustment plate, thereby reducing noise.

[0015] Furthermore, the adjustment plate is L-shaped, the adjustment plate is made of silicon steel, and the short side of the adjustment plate is located on the surface of the rotor.

[0016] By setting the adjustment plate to be L-shaped, the adjustment plate can capture magnetic waves more easily. At the same time, the L-shaped adjustment plate setting is also beneficial to the heat dissipation of the adjustment plate. By setting the short side of the adjustment plate to be located on the surface of the rotor, the adjustment plate can capture harmonics more easily.

[0017] Furthermore, the noise detection device includes a detection shell, an upper cover, a lower cover, a diaphragm, a piezoelectric ceramic sheet, an electrode sheet and a screw. The detection shell and the upper cover are fastened together, the detection shell and the lower cover are connected, the lower cover and the motor housing are fastened together, the diaphragm and the upper cover are connected, the side of the diaphragm away from the upper cover is fastened together with the detection shell, the piezoelectric ceramic sheet is placed in the detection shell, there are several piezoelectric ceramic sheets, the electrode sheet is placed in the detection shell, there are several electrode sheets, the piezoelectric ceramic sheets and the electrode sheets are staggered, the detection shell, the lower cover, the piezoelectric ceramic sheet and the electrode sheet are connected by a screw, and the electrode sheet is electrically connected to the processor.

[0018] The detection shell serves as the main installation base and is used for installation and positioning with other components. The detection shell, piezoelectric ceramic sheet, electrode sheet and lower cover are connected by screws. At the same time, the piezoelectric ceramic sheet and electrode sheet are pressed tightly by applying pre-tightening force to the screws. When harmonics appear and noise is emitted, the noise emitted by the harmonics is reduced by the adjustment plate. At the same time, the noise is transmitted to the diaphragm, causing the diaphragm to vibrate. The vibration of the diaphragm causes the diaphragm to impact the piezoelectric ceramic sheet, thereby causing the piezoelectric ceramic sheet and electrode sheet to generate current. When the noise is reduced, the current on the piezoelectric ceramic sheet and electrode sheet is reduced. The adjustment effect of the adjustment plate is detected by the electrical signals on the piezoelectric ceramic sheet and electrode sheet. When the adjustment plate rotates too much, the harmonics offset by the adjustment plate are reduced, thereby increasing the noise generated by the harmonics in the motor. At this time, the electrical signals on the piezoelectric ceramic sheet and electrode sheet increase, and then the processor processes the electrical signals on the piezoelectric ceramic sheet and electrode sheet to adjust the adjustment plate, thereby improving the noise reduction effect.

[0019] Furthermore, the upper cover is provided with a plurality of through holes.

[0020] The upper cover is provided with a plurality of through holes, thereby improving the noise signal received by the diaphragm.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The magnetic field detection device features symmetrically placed first and second detection coils with opposite rotations, offsetting the stator's own magnetic field interference and capturing magnetic flux changes in the air gap between the stator and rotor. By amplifying and processing the induced current signal, the processor enables real-time monitoring of the air gap's harmonic magnetic field, providing precise data support for subsequent noise reduction adjustments.

[0022] 2. The adjustment device utilizes first and second metal sheets with different thermal expansion coefficients in conjunction with an L-shaped silicon steel adjustment plate, enabling real-time position adjustment based on processor output signals. When air gap harmonics are detected, the thermal deformation of the metal sheets drives the adjustment plate to rotate. The resulting magnetic field specifically offsets the air gap harmonic magnetic field, reducing electromagnetic noise generated by the interaction of harmonics and stator current at its source, resulting in more proactive and precise noise reduction.

[0023] 3. The noise detection device receives motor noise through the diaphragm and converts the vibration signal into an electrical signal using piezoelectric ceramics and electrodes, which is then fed back to the processor, forming a closed-loop control system of "detection-adjustment-redetection." If the adjustment device over-adjusts, causing the noise to rise again, the processor can promptly correct the adjustment parameters to ensure stable and reliable noise reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 Schematic diagram of the stator structure of the present invention; Figure 3 Schematic diagram of the structure of the magnetic field detection device of the present invention; Figure 4 It is a schematic structural diagram of the regulating device of the present invention; Figure 5 for Figure 4 A magnified view of the local area A; Figure 6 Schematic diagram of the rotor structure of the present invention; Figure 7 Schematic diagram of the noise detection device of the present invention.

[0025] In the figure: 1. Motor housing; 2. Stator; 3. Rotor; 4. Magnetic field detection device; 41. First detection coil; 42. Second detection coil; 43. Processor; 5. Adjustment device; 51. Adjustment ring; 52. Adjustment plate; 53. First metal sheet; 54. Second metal sheet; 6. Noise detection device; 61. Detection shell; 62. Upper cover; 621. Through hole; 63. Lower cover; 64. Diaphragm; 65. Piezoelectric ceramic sheet; 66. Electrode sheet; 67. Screw; 7. Auxiliary magnet. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example: Figure 1-Figure 7 As shown, the present invention provides a technical solution for a rare earth-free permanent magnet synchronous motor with a noise reduction function, including a motor housing 1, a stator 2, a rotor 3, a magnetic field detection device 4, an adjustment device 5 and a noise detection device 6. The stator 2 is placed in the motor housing 1, the rotor 3 is placed in the stator 2, the magnetic field detection device 4 is placed outside the stator 2, there are two adjustment devices 5, and the two adjustment devices 5 are respectively connected to the stator 2 and the rotor 3. The noise detection device 6 is placed in the motor housing 1, the noise detection device 6 is fastened to the motor housing 1, the magnetic field detection device 4 is electrically connected to the adjustment device 5, and the noise detection device 6 is electrically connected to the magnetic field detection device 4.

[0028] The motor housing 1 serves as the main installation base for the installation and positioning of other components. After the equipment is assembled, the magnetic flux change of the air gap between the stator 2 and the rotor 3 is detected by the magnetic field detection device 4. According to the magnetic flux change of the air gap detected by the magnetic field detection device 4, the magnetic field detection device 4 outputs a signal to deflect the adjustment device 5. By deflecting the adjustment device 5, the magnetic fields between the adjustment device 5 and the air gap cancel each other out, thereby reducing the magnetic flux change of the air gap and the harmonic amplitude causing the change of the air gap magnetic flux, so that the harmonic magnetic field of the air gap will not combine with the current of the stator 2 to generate noise. The adjustment position of the adjustment device 5 is detected by the noise detection device 6. When the adjustment device 5 is deflected, the noise gradually decreases. The noise signal is detected by the noise detection device 6. When the noise increases from small to large, the noise detection device 6 feeds back an electrical signal to adjust the adjustment device 5 to prevent the adjustment device 5 from adjusting the position too much, thereby reducing the effect of noise regulation.

[0029] like Figure 1-Figure 3 As shown, the magnetic field detection device 4 includes a first detection coil 41, a second detection coil 42 and a processor 43. The first detection coil 41 and the second detection coil 42 are equal in size, the first detection coil 41 and the second detection coil 42 have the same number of turns, the first detection coil 41 and the second detection coil 42 have opposite rotation directions, the first detection coil 41 and the second detection coil 42 are connected by wires, the first detection coil 41 and the processor 43 are connected by wires, and the first detection coil 41 and the second detection coil 42 are symmetrically placed.

[0030] By setting the first detection coil 41 and the second detection coil 42, and setting the first detection coil and the second detection coil 42 to have the same number of turns and be wound in opposite directions in series, the magnetic flux changes of the magnetic field emitted by the stator 2 itself in the first detection coil 41 and the second detection coil 42 are the same but in opposite directions, thereby eliminating the interference of the magnetic field changes of the stator 2 detected by the first detection coil 41 and the second detection coil 42, so that the first detection coil 41 and the second detection coil 42 can detect the magnetic flux changes in the air gap between the stator 2 and the rotor 3. When the magnetic field amount in the air gap between the stator 2 and the rotor 3 changes, the change in magnetic flux causes the magnetic flux between the first detection coil 41 and the second detection coil 42 to change, and then the induced current generated by the first detection coil 41 and the second detection coil 42 is amplified by the processor 43.

[0031] like Figure 2-Figure 3 As shown, the processor 43 is used to process the electrical signals of the first detection coil 41 and the second detection coil 42 , and the processor 43 is electrically connected to the adjustment device 5 .

[0032] The processor 43 processes the electrical signals of the first detection coil 41 and the second detection coil 42, amplifies the electrical signals of the first detection coil 41 and the second detection coil 42, and then outputs the signal to the adjustment device 5. The adjustment device 5 offsets the harmonics of the air gap, thereby reducing noise.

[0033] like Figure 2-Figure 3 As shown, an auxiliary magnet 7 is provided in the gap of the stator 2, and the auxiliary magnet 7 is ferrite.

[0034] By arranging the auxiliary magnets 7 between the gaps of the stator 2, the space of the air gap is reduced, and the source of noise generated by the air gap is reduced, thereby reducing the noise.

[0035] like Figure 4-Figure 6 As shown, the adjusting device 5 includes an adjusting ring 51, an adjusting plate 52, a first metal sheet 53 and a second metal sheet 54. The adjusting ring 51 is rotatably connected to the rotor 3. A plurality of adjusting plates 52 are provided on the adjusting ring 51. The plurality of adjusting rings 51 are rotatably connected to the adjusting plates 52. The first metal sheet 53 is rotatably connected to the rotor 3. The first metal sheet 53 is fastened to the second metal sheet 54 on a side away from the rotor 3. The second metal sheet 54 is fastened to the adjusting plate 52 on a side away from the first metal sheet 53. The thermal expansion coefficient of the first metal sheet 53 is greater than the thermal expansion coefficient of the second metal sheet 54. The processor 43 is connected to the first metal sheet 53 by wires.

[0036] The middle part of the second metal sheet 54 and the adjustment plate 52 are connected through a fixed plate. The adjustment plate 52 is deflected at a certain angle during installation. When the first detection coil 41 and the second detection coil 42 detect the change in the magnetic flux of the air gap, the first metal sheet 53 is energized through the processor 43. When high-order harmonics emitted by the air gap magnetic field are detected, the magnetic flux changes greatly, and the induced current generated by the processor 43 is large. The first metal sheet 53 is energized by the processor 43 so that the first metal sheet 53 is heated and collided, causing the inside of the first metal sheet 53 to concave. The concave inside of the first metal sheet 53 drives the inside of the second metal sheet 54 to concave, driving the fixed plate to concave, thereby driving the adjustment plate 52 to rotate. The adjustment plate 52 rotates so that the magnetic field and the harmonic magnetic field emitted by the adjustment plate 52 are offset, thereby reducing noise.

[0037] like Figure 5 As shown, the adjustment plate 52 is L-shaped, the adjustment plate 52 is made of silicon steel, and the short side of the adjustment plate 52 is located on the surface of the rotor 3.

[0038] By setting the adjustment plate 52 to be L-shaped, the adjustment plate 52 can more easily capture magnetic waves. At the same time, the L-shaped adjustment plate 52 is also beneficial to the heat dissipation of the adjustment plate 52. By setting the short side of the adjustment plate 52 to be located on the surface of the rotor 3, the adjustment plate 52 can more easily capture harmonics.

[0039] like Figure 2 and Figure 7 As shown, the noise detection device 6 includes a detection shell 61, an upper cover 62, a lower cover 63, a diaphragm 64, a piezoelectric ceramic piece 65, an electrode piece 66 and a screw 67. The detection shell 61 and the upper cover 62 are fastened together, the detection shell 61 and the lower cover 63 are connected, the lower cover 63 and the motor housing 1 are fastened together, the diaphragm 64 and the upper cover 62 are connected, and the side of the diaphragm 64 away from the upper cover 62 is fastened together with the detection shell 61. The piezoelectric ceramic piece 65 is placed in the detection shell 61, and there are several piezoelectric ceramic pieces 65. The electrode piece 66 is placed in the detection shell 61, and there are several electrode pieces 66. The piezoelectric ceramic pieces 65 and the electrode pieces 66 are staggered. The detection shell 61, the lower cover 63, the piezoelectric ceramic piece 65 and the electrode piece 66 are connected by a screw 67, and the electrode piece 66 is electrically connected to the processor 43.

[0040] The detection shell 61 is used as the main installation base for installation and positioning with other components. The detection shell 61, the piezoelectric ceramic sheet 65, the electrode sheet 66 and the lower cover 63 are connected by the screw 67. At the same time, the piezoelectric ceramic sheet 65 and the electrode sheet 66 are pressed tightly by applying a pre-tightening force to the screw 67. When the harmonic appears and emits noise, the noise emitted by the harmonic is reduced by the adjustment plate 52. At the same time, the noise is transmitted to the diaphragm 64, causing the diaphragm 64 to vibrate. The vibration of the diaphragm 64 causes the diaphragm 64 to impact the piezoelectric ceramic sheet 65, thereby causing the piezoelectric ceramic sheet 65 to vibrate. 5 and the electrode sheet 66 generate current. When the noise is reduced, the current on the piezoelectric ceramic sheet 65 and the electrode sheet 66 is reduced. The regulating effect of the regulating plate 52 is detected by the electrical signals on the piezoelectric ceramic sheet 65 and the electrode sheet 66. When the regulating plate 52 rotates too much, the harmonics offset by the regulating plate 52 are reduced, thereby increasing the noise generated by the harmonics in the motor. At this time, the electrical signals on the piezoelectric ceramic sheet 65 and the electrode sheet 66 increase. Then, the processor 43 processes the electrical signals on the piezoelectric ceramic sheet 65 and the electrode sheet 66 to adjust the regulating plate 52, thereby improving the noise reduction effect.

[0041] like Figure 7 As shown, the upper cover 62 is provided with a plurality of through holes 621 .

[0042] The upper cover 62 is provided with a plurality of through holes 621 , thereby increasing the noise signal received by the diaphragm 64 .

[0043] The working principle of the present invention: the motor housing 1 is used as the main installation base for the installation and positioning of other components. After the equipment is assembled, the first detection coil 41 and the second detection coil 42 are set, and the first detection coil and the second detection coil 42 are set to have the same number of turns and are wound in opposite directions in series, so that the magnetic field emitted by the stator 2 itself has the same magnetic flux changes in the first detection coil 41 and the second detection coil 42 but in opposite directions, thereby eliminating the interference of the stator 2 magnetic field changes detected by the first detection coil 41 and the second detection coil 42, so that the first detection coil 41 and the second detection coil 42 can detect the magnetic flux changes in the air gap between the stator 2 and the rotor 3. When the magnetic field amount in the air gap between the stator 2 and the rotor 3 changes, the change in magnetic flux causes the magnetic flux between the first detection coil 41 and the second detection coil 42 to change, and then the first detection coil 41 and the second detection coil 42 are connected in series. The induced current generated by the measuring coil 42 is amplified by the processor 43, and then the processor 43 energizes the first metal sheet 53. When high-order harmonics emitted by the air gap magnetic field are detected, the magnetic flux changes greatly, and the induced current generated by the processor 43 is large. The processor 43 energizes the first metal sheet 53 so that the first metal sheet 53 is heated and collided, causing the interior of the first metal sheet 53 to concave. The concave interior of the first metal sheet 53 drives the interior of the second metal sheet 54 to concave, driving the fixed plate to concave, thereby driving the adjustment plate 52 to rotate. The rotation of the adjustment plate 52 cancels out the magnetic field and the harmonic magnetic field emitted by the adjustment plate 52, thereby reducing noise. When the adjustment plate 52 deflects, the noise gradually decreases. The noise signal is detected by the noise detection device 6. When the noise increases from small to large, the noise detection device 6 feeds back an electrical signal to adjust the adjustment device 5 to prevent the adjustment device 5 from adjusting the position too much, thereby reducing the effect of noise regulation.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A rare earth-free permanent magnet synchronous motor with noise reduction function, characterized by: The synchronous motor comprises a motor housing (1), a stator (2), a rotor (3), a magnetic field detection device (4), an adjustment device (5) and a noise detection device (6), wherein the stator (2) is placed in the motor housing (1), the rotor (3) is placed in the stator (2), the magnetic field detection device (4) is placed outside the stator (2), there are two adjustment devices (5), and the two adjustment devices (5) are respectively connected to the stator (2) and the rotor (3), the noise detection device (6) is placed in the motor housing (1), the noise detection device (6) and the motor housing (1) are fastened together, the magnetic field detection device (4) and the adjustment device (5) are electrically connected, and the noise detection device (6) and the magnetic field detection device (4) are electrically connected.

2. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 1, characterized in that: The magnetic field detection device (4) comprises a first detection coil (41), a second detection coil (42) and a processor (43); the first detection coil (41) and the second detection coil (42) are equal in size; the first detection coil (41) and the second detection coil (42) have the same number of turns; the first detection coil (41) and the second detection coil (42) have opposite rotation directions; the first detection coil (41) and the second detection coil (42) are connected by a wire; the first detection coil (41) and the processor (43) are connected by a wire; and the first detection coil (41) and the second detection coil (42) are symmetrically placed.

3. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 2, characterized in that: The processor (43) is used to process the electrical signals of the first detection coil (41) and the second detection coil (42), and the processor (43) is electrically connected to the adjustment device (5).

4. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 1, characterized in that: An auxiliary magnet (7) is provided in the gap of the stator (2), and the auxiliary magnet (7) is ferrite.

5. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 3, characterized in that: The regulating device (5) comprises an regulating ring (51), an regulating plate (52), a first metal sheet (53) and a second metal sheet (54); the regulating ring (51) is rotatably connected to the rotor (3); a plurality of regulating plates (52) are provided on the regulating ring (51); the plurality of regulating rings (51) and the regulating plates (52) are rotatably connected; the first metal sheet (53) is rotatably connected to the rotor (3); a side of the first metal sheet (53) away from the rotor (3) is fastened to the second metal sheet (54); a side of the second metal sheet (54) away from the first metal sheet (53) is fastened to the regulating plate (52); a thermal expansion coefficient of the first metal sheet (53) is greater than a thermal expansion coefficient of the second metal sheet (54); and the processor (43) and the first metal sheet (53) are connected by wires.

6. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 5, characterized in that: The adjustment plate (52) is L-shaped, the adjustment plate (52) is made of silicon steel, and the short side of the adjustment plate (52) is located on the surface of the rotor (3).

7. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 3, characterized in that: The noise detection device (6) comprises a detection shell (61), an upper cover (62), a lower cover (63), a diaphragm (64), a piezoelectric ceramic sheet (65), an electrode sheet (66) and a screw (67), wherein the detection shell (61) and the upper cover (62) are fastened together, the detection shell (61) and the lower cover (63) are connected, the lower cover (63) and the motor housing (1) are fastened together, the diaphragm (64) and the upper cover (62) are connected, and the diaphragm (64) is away from the side of the upper cover (62) and the detection shell ( 61) is fastened and connected, the piezoelectric ceramic sheet (65) is placed in the detection shell (61), there are a plurality of piezoelectric ceramic sheets (65), the electrode sheet (66) is placed in the detection shell (61), there are a plurality of electrode sheets (66), the piezoelectric ceramic sheets (65) and the electrode sheets (66) are staggered, the detection shell (61), the lower cover (63), the piezoelectric ceramic sheet (65) and the electrode sheet (66) are connected by a screw (67), and the electrode sheet (66) is electrically connected to the processor (43).

8. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 7, characterized in that: The upper cover (62) is provided with a plurality of through holes (621).

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