A rare earth-free permanent magnet synchronous motor with noise reduction function

Abstract

The application 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 installation base for the installation and positioning of other components. After the equipment is assembled, a magnetic field detection device is used to detect the magnetic flux variation of the air gap between the stator and the rotor. According to the magnetic flux variation of the air gap detected by the magnetic field detection device, the output signal of the magnetic field detection device causes the deflection of an adjusting device. The deflection of the adjusting device causes the magnetic field between the adjusting device and the air gap to offset each other, thereby reducing the magnetic flux variation of the air gap and the harmonic amplitude causing the magnetic flux variation of the air gap, so that the harmonic magnetic field of the air gap cannot combine with the current of the stator to generate noise. A noise detection device is used to detect the adjusting position of the adjusting device. When the adjusting device deflects, the noise gradually decreases. When the noise changes from small to large, the noise detection device feeds back an electric signal to adjust the adjusting device.

Description

TECHNICAL FIELD

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

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

[0003] Noise during motor operation has always been a problem in the industry. Existing motor noise is mainly caused by harmonic fluctuations in the air gap magnetic field between the stator and the rotor, mechanical structure vibration, etc., among which the electromagnetic noise generated by the interaction of air gap harmonic magnetic field and stator current is particularly prominent. Traditional noise reduction methods mostly use passive sound insulation or structural reinforcement, lack real-time detection and dynamic adjustment capability of air gap magnetic field harmonics, and are difficult to accurately cancel harmonic interference, resulting in limited noise reduction effect; and some designs are not optimized for air gap structure, further exacerbating the generation of noise sources. In addition, the traditional adjustment device has a lagging response and cannot adjust in real time according to the magnetic field changes, which is prone to over-adjustment or insufficient adjustment, affecting the stability of the motor operation and the noise reduction efficiency. SUMMARY

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

[0005] To achieve the above purpose, the present application provides the following technical scheme:

[0006] A rare-earth-free permanent magnet synchronous motor with noise reduction function, comprising 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, the adjustment device has two, the two adjustment devices are respectively connected with the stator and the rotor, the noise detection device is placed in the motor housing, the noise detection device and the motor housing are tightly connected, the magnetic field detection device and the adjustment device are electrically connected, and the noise detection device and the magnetic field detection device are electrically connected.

[0007] The motor housing is used as a main mounting base for mounting and positioning other components. After the equipment is assembled, the magnetic flux variation of the air gap between the stator and the rotor is detected by the magnetic field detection device. According to the magnetic flux variation of the air gap detected by the magnetic field detection device, the magnetic field detection device outputs a signal to cause the adjusting device to deflect. Through the deflection of the adjusting device, the magnetic field between the adjusting device and the air gap is offset, thereby reducing the magnetic flux variation of the air gap and the harmonic amplitude causing the magnetic flux variation of the air gap, so that the harmonic magnetic field of the air gap cannot combine with the current of the stator to produce noise. The adjusting position of the adjusting device is detected by the noise detection device. When the adjusting device deflects, the noise gradually decreases. The noise signal is detected by the noise detection device. When the noise changes from small to large, the noise detection device feeds back an electric signal to adjust the adjusting device to prevent the adjusting position of the adjusting device from being adjusted too much, thereby reducing the effect of noise adjustment.

[0008] Further, 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, have the same number of turns, and have opposite winding 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. The first detection coil and the second detection coil are symmetrically placed.

[0009] By setting the first detection coil and the second detection coil, and simultaneously setting the first detection coil and the second detection coil to have the same number of turns and opposite winding directions, the magnetic field emitted by the stator is the same in the first detection coil and the second detection coil but opposite in direction, thereby eliminating the interference of the stator magnetic field change detected by the first detection coil and the second detection coil. The first detection coil and the second detection coil can detect the magnetic flux variation between the stator and the rotor. When the magnetic field between the stator and the rotor changes, the magnetic flux between the first detection coil and the second detection coil changes, and then the induced current of the first detection coil and the second detection coil is amplified by the processor.

[0010] Further, the processor is used to process the electric signals of the first detection coil and the second detection coil, and the processor is electrically connected to the adjusting device.

[0011] The processor processes the electric signals of the first detection coil and the second detection coil, amplifies the electric signals of the first detection coil and the second detection coil, and then outputs a signal to the adjusting device. The adjusting device offsets the harmonics of the air gap, thereby reducing the noise.

[0012] Further, an auxiliary magnet is arranged in the stator gap, and the auxiliary magnet is a ferrite.

[0013] By setting the auxiliary magnet between the stator gap, thereby reducing the presence of air gap space, reducing the noise source of air gap, thereby reducing the noise.

[0014] Further, the adjusting device comprises an adjusting ring, an adjusting plate, a first metal sheet and a second metal sheet, the adjusting ring is rotationally connected with the rotor, the adjusting ring is provided with a plurality of adjusting plates, the plurality of adjusting rings and the adjusting plates are rotationally connected, the first metal sheet is rotationally connected with the rotor, the side of the first metal sheet away from the rotor is fixedly connected with the second metal sheet, the side of the second metal sheet away from the first metal sheet is fixedly connected with the adjusting plate, the thermal expansion coefficient of the first metal sheet is greater than that of the second metal sheet, and the processor is in wire connection with the first metal sheet.

[0015] The middle part of the second metal sheet and the adjusting plate are connected through a fixing plate, the adjusting plate has a certain angular deflection when being 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 harmonic of the magnetic field of the air gap is detected, the change of the magnetic flux is large, the induced current generated by the processor is large, the first metal sheet is heated and collided by being energized through the processor, the inside of the first metal sheet is concave, the inside of the second metal sheet is concave, the fixing plate is concave, and the adjusting plate is rotated, the magnetic field emitted by the adjusting plate is offset by the harmonic magnetic field, and thus the noise is reduced.

[0016] Further, the adjusting plate is in the shape of L, the adjusting plate is made of silicon steel, and the short side of the adjusting plate is located on the surface of the rotor.

[0017] The adjusting plate is in the shape of L, so that the adjusting plate can more easily capture magnetic waves, and the L-shaped adjusting plate is also conducive to heat dissipation of the adjusting plate, and the short side of the adjusting plate is located on the surface of the rotor, so that the adjusting plate can more easily capture the harmonic.

[0018] Further, the noise detection device comprises a detection shell, an upper cover, a lower cover, a diaphragm, a piezoelectric ceramic sheet, an electrode sheet and a screw rod, the detection shell and the upper cover are fixedly connected, the detection shell and the lower cover are connected, the lower cover and the motor shell are fixedly connected, the diaphragm and the upper cover are connected, the side of the diaphragm away from the upper cover is fixedly connected with the detection shell, the piezoelectric ceramic sheet is arranged in the detection shell, the piezoelectric ceramic sheet has a plurality of piezoelectric ceramic sheets, the electrode sheet is arranged in the detection shell, the electrode sheet has a plurality of electrode sheets, the piezoelectric ceramic sheet and the electrode sheet are staggered, the detection shell, the lower cover, the piezoelectric ceramic sheet and the electrode sheet are connected through the screw rod, and the electrode sheet is electrically connected with the processor.

[0019] The detection shell is used as a main installation base for installation and positioning with other components, the detection shell, the piezoelectric ceramic sheet, the electrode sheet and the lower cover are connected through the screw rod, the piezoelectric ceramic sheet and the electrode sheet are pressed tightly by applying a pre-tightening force to the screw rod, when the harmonic appears and noise is emitted, the noise emitted by the harmonic is reduced through the adjusting plate, at the same time, the noise is transmitted to the diaphragm to make the diaphragm vibrate, the diaphragm impacts the piezoelectric ceramic sheet through the vibration of the diaphragm, so that the piezoelectric ceramic sheet and the electrode sheet generate an electric current, when the noise is weakened, the electric current on the piezoelectric ceramic sheet and the electrode sheet is weakened, the adjusting effect of the adjusting plate is detected through the electric signal on the piezoelectric ceramic sheet and the electrode sheet, when the adjusting plate rotates too much, the harmonic offset by the adjusting plate is reduced, so that the noise generated by the harmonic in the motor is strengthened, at this time, the electric signal on the piezoelectric ceramic sheet and the electrode sheet is increased, and then the adjusting plate is adjusted through the processor processing the electric signal on the piezoelectric ceramic sheet and the electrode sheet, so as to improve the noise reduction effect.

[0020] Further, the upper cover is provided with a plurality of through holes.

[0021] Through the plurality of through holes provided on the upper cover, the noise signal received by the diaphragm is improved.

[0022] Compared with the prior art, the beneficial effects of the present application are:

[0023] 1. The magnetic field detection device adopts the design that the first and second detection coils are symmetrically placed and the rotation directions are opposite, which can offset the interference of the stator's own magnetic field and capture the magnetic flux change of the air gap between the stator and the rotor. Through the amplification and processing of the processor on the induced current signal, real-time monitoring of the air gap harmonic magnetic field is realized, which provides accurate data support for subsequent noise reduction adjustment.

[0024] 2. The adjusting device can adjust the posture in real time according to the processor output signal through the cooperation of the first and second metal sheets with different thermal expansion coefficients and the L-shaped silicon steel adjusting plate. When the air gap harmonic is detected, the metal sheet is deformed by heat to drive the adjusting plate to rotate, and the magnetic field generated by the adjusting plate can specifically offset the air gap harmonic magnetic field, thereby reducing the electromagnetic noise generated by the harmonic and the stator current from the source, and the noise reduction effect is more active and more accurate.

[0025] 3. The noise detection device receives the motor noise through the diaphragm, converts the vibration signal into an electric signal through the piezoelectric ceramic sheet and the electrode sheet, and feeds back the electric signal to the processor to form a closed-loop control of "detection-adjustment-detection again". When the adjusting device over-adjusts and causes the noise to rise again, the processor can correct the adjusting parameters in time to ensure the stability and reliability of the noise reduction effect. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a general structure schematic diagram of the present application;

[0027] Figure 2Schematic diagram of the stator structure of the present invention;

[0028] Figure 3 Schematic diagram of the structure of the magnetic field detection device of the present invention;

[0029] Figure 4 It is a structural schematic diagram of the regulating device of the present invention;

[0030] Figure 5 for Figure 4 A magnified view of the local area A;

[0031] Figure 6 Schematic diagram of the rotor structure of the present invention;

[0032] Figure 7 Schematic diagram of the noise detection device of the present invention.

[0033] 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

[0034] 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.

[0035] Example: Figures 1-7 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.

[0036] 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 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 cause the adjusting device 5 to deflect. Through the deflection of the adjusting device 5, the magnetic field between the adjusting device 5 and the air gap is offset, thereby reducing the magnetic flux change of the air gap and the harmonic amplitude causing the magnetic flux change of the air gap, so that the harmonic magnetic field of the air gap cannot combine with the current of the stator 2 to produce noise. The adjusting position of the adjusting device 5 is detected by the noise detection device 6. When the adjusting device 5 deflects, the noise gradually decreases. When the noise changes from small to large, the noise detection device 6 feeds back an electrical signal to the adjusting device 5 for adjustment, preventing the adjusting device 5 from adjusting the adjusting position too much, thereby reducing the effect of noise adjustment.

[0037] As shown in Figures 1-3 , 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, have the same number of turns, and have opposite winding 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. The first detection coil 41 and the second detection coil 42 are symmetrically placed.

[0038] 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 opposite winding directions, the magnetic field emitted by the stator 2 itself has the same magnetic flux change but opposite directions in the first detection coil 41 and the second detection coil 42, thereby eliminating the interference of the stator 2 magnetic field change 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 change between the air gap between the stator 2 and the rotor 3. When the magnetic field between the stator 2 and the rotor 3 changes, the magnetic flux between the first detection coil 41 and the second detection coil 42 changes, and then the induced current generated by the first detection coil 41 and the second detection coil 42 is amplified by the processor 43.

[0039] As shown in Figures 2-3 , the processor 43 is used to process the electrical signals of the first detection coil 41 and the second detection coil 42. The processor 43 and the adjusting device 5 are electrically connected.

[0040] 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.

[0041] like Figures 2-3 As shown, an auxiliary magnet 7 is provided in the gap of the stator 2, and the auxiliary magnet 7 is ferrite.

[0042] 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.

[0043] like Figures 4-6 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] likeFigure 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.

[0048] 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.

[0049] like Figure 7 As shown, the upper cover 62 is provided with a plurality of through holes 621 .

[0050] The upper cover 62 is provided with a plurality of through holes 621 , thereby increasing the noise signal received by the diaphragm 64 .

[0051] The working principle of the present application is as follows: the motor shell 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 arranged, the first detection coil and the second detection coil 42 are arranged to have the same number of turns and opposite winding directions, so that the magnetic flux of the magnetic field emitted by the stator 2 in the first detection coil 41 and the second detection coil 42 changes in the same way but in opposite directions, thereby excluding the interference of the stator 2 magnetic field change 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 change between the air gap between the stator 2 and the rotor 3, when the magnetic field between the air gap between the stator 2 and the rotor 3 changes, the magnetic flux between the first detection coil 41 and the second detection coil 42 changes due to the change of the magnetic flux, then the induced current generated by the first detection coil 41 and the second detection coil 42 is amplified by the processor 43, and then the processor 43 energizes the first metal sheet 53, when detecting the high-order harmonic of the air gap magnetic field, the magnetic flux changes greatly, the induced current generated by the processor 43 is large, and the first metal sheet 53 is heated and collided by the energization of the processor 43, so that the first metal sheet 53 is internally concave, the second metal sheet 54 is internally concave, and the fixed plate is concave, thereby driving the adjusting plate 52 to rotate, and the adjusting plate 52 emits a magnetic field which offsets the harmonic magnetic field by rotating the adjusting plate 52, thereby reducing the noise, when the adjusting plate 52 deflects, the noise gradually decreases, and the noise signal is detected by the noise detection device 6, when the noise changes from small to large, the noise detection device 6 feeds back the electric signal to the adjusting device 5 for adjustment, to prevent the adjusting device 5 from adjusting the position too much, thereby reducing the effect of noise adjustment.

[0052] It is apparent for a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and it is intended to embrace all changes and modifications that fall within the meaning and scope of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

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), 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; 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; 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.

2. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 1, 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).

3. 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.

4. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 1, 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).

5. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 2, 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).

6. The rare earth-free permanent magnet synchronous motor with noise reduction function according to claim 5, characterized in that: The upper cover (62) is provided with a plurality of through holes (621).

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