An electric motor and a control method thereof

Abstract

The application relates to a motor and a control method thereof, the motor comprising a magnetic damping adjusting device, the magnetic damping adjusting device comprising: a first magnetic induction fluid damping piece arranged between a rotating shaft and an inner ring of a bearing; and / or the magnetic damping adjusting device comprising: a second magnetic induction fluid damping piece arranged between an outer ring of the bearing and a shell. By changing the magnetic field around the magnetic induction fluid damping piece, the application can effectively reduce the noise of the motor, especially the commutation noise problem of the DC motor. The application can reduce the vibration of the motor set by identifying the commutation noise and adjusting the variable damping vibration reduction device to control the vibration transmission of the rotor of the motor. By gradually adjusting the resistance value of the adjustable resistor and combining noise detection, the loss factor is obtained, the adjustable resistor is adjusted according to the resistance value corresponding to the maximum loss factor, the commutation noise problem of the motor set can be significantly improved, and the operation quality of the motor set is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrical appliances, in particular to an electric motor and a control method thereof. BACKGROUND

[0002] Commonly, an electric motor such as a direct current motor generates relatively obvious commutation noise when operating at a certain speed, which has a great impact on the sound quality of the product. The commutation noise, such as resonance noise, has a strong correlation with the vibration of the motor, so that the vibration of the motor is suppressed, and the noise will also be attenuated. The commutation noise of the direct current motor is caused by the unbalanced electromagnetic force, which makes the rotor vibrate greatly. The vibration on the rotor is directly transmitted to the motor shell, the stator and the motor frame through the bearing. In addition, the vibration on the rotor is further amplified to the stator due to the influence of the precision and assembly quality of the bearing itself. If there is a certain order of natural frequency close to the commutation frequency in the stator or the system, the resonance of the motor will be caused, thereby generating the commutation noise. To solve such commutation noise, improvements should be made from the noise source and the transmission path. From the noise source, the balance of the unbalanced electromagnetic force is controlled, which requires the rotor itself to have higher dynamic and static balance, and at the same time, the air gap distance between the stator and the rotor should be appropriate and the magnetic field should be uniform, so as to reduce the excitation of the unbalanced electromagnetic force to the rotor; the vibration isolation on the transmission path needs to be carried out between the rotor and the bearing, and the bearing and the motor shell, so as to reduce the vibration of the motor and the resonance noise of the motor.

[0003] The existing magnetorheological fluid is an intelligent fluid material composed of non-magnetic base fluid, small magnetic particles and surfactant. The surface viscosity and flowability of the magnetorheological fluid are affected by the strength of the magnetic field, and the property change of the magnetorheological fluid with the strength of the magnetic field is reversible. In the absence of a magnetic field, the small magnetic particles of the magnetorheological fluid are in a free motion state and are randomly distributed in the magnetorheological fluid, which exhibits the characteristics of low viscosity and strong flowability; in the presence of a magnetic field, the small magnetic particles will form a linear chain structure along the direction of the magnetic field, so that the shear stress of the magnetorheological fluid in the direction of the magnetic field increases. The difference in viscosity and flowability of the magnetorheological fluid in different magnetic fields enables it to exhibit different damping forces and damping torques, which have different damping effects on system vibration.

[0004] In order to solve the problem of the influence of the commutation noise of the direct current motor of the fresh air machine on the sound quality of the product, the present application designs a new type of direct current motor structure with a variable damping vibration reduction device by using the unique properties of the magnetorheological fluid. The variable damping vibration reduction device is added between the motor rotor and the inner ring of the bearing, and between the outer ring of the bearing and the motor shell. The damping adjustment is carried out for the vibration transmission in the frequency band of the commutation noise by using the vibration reduction device combined with the control system to identify the commutation noise of the direct current motor, so as to weaken the vibration transmission from the motor rotor to the unit, optimize the commutation noise of the whole machine and improve the sound quality of the unit. SUMMARY

[0005] In view of this, the present application provides an electric machine and a control method thereof to solve the problem that the rotor of the electric machine vibrates excessively due to unbalanced electromagnetic force at certain rotational speeds, and the vibration of the rotor is transmitted to the machine housing, the stator of the housing and the machine set through contact with the bearing, and the vibration is amplified during the transmission process and resonance occurs, further amplifying the vibration. The present application preferably suppresses the vibration of the DC motor, which is easily amplified during the transmission process to generate commutation noise. The preferred DC motor with a variable damping vibration reduction device of the present application can identify the commutation noise and adjust the magnetic induction variable damping device according to the vibration condition of the motor, so that the damping effect of the variable damping device reaches the best effect.

[0006] In particular, an electric machine comprises: a housing, a rotor, a rotating shaft of the rotor, a bearing cooperating with the rotating shaft, the bearing comprising an inner ring and an outer ring; the outer ring of the bearing is fixed with the housing, and the inner ring of the bearing is fixed with the rotating shaft; and further comprising a magnetic damping adjustment device; the magnetic damping adjustment device comprises: a first magnetic induction fluid damping member, which is arranged between the rotating shaft and the inner ring of the bearing; and / or, the magnetic damping adjustment device comprises: a second magnetic induction fluid damping member, which is arranged between the outer ring of the bearing and the housing.

[0007] Preferably, a first groove is arranged on the rotating shaft, and the first magnetic induction fluid damping member is arranged in the first groove.

[0008] Preferably, the first groove is a first annular groove, and the first magnetic induction fluid damping member is a first annular structure, which is annularly arranged in the first groove, and the depth of the first groove is substantially equal to the thickness of the first annular structure.

[0009] Preferably, a second groove is arranged on the housing, and the second magnetic induction fluid damping member is arranged in the second groove.

[0010] Preferably, the second groove is a second annular groove, and the second magnetic induction fluid damping member is a second annular structure, which is annularly arranged in the second groove, and the depth of the second groove is greater than the thickness of the second annular structure, and part of the outer ring is located in the second annular groove.

[0011] Preferably, the magnetic damping adjustment device comprises: a first coil, and the magnetic field around the first magnetic induction fluid damping member can be adjusted by changing the current passing through the first coil; and / or, the magnetic damping adjustment device further comprises: a second coil, and the magnetic field around the second magnetic induction fluid damping member can be adjusted by changing the current passing through the second coil.

[0012] Preferably, the electric machine is a DC motor.

[0013] The application also provides a control method of the motor, wherein the magnetic field around the first magnetic induction fluid damping member and / or the second magnetic induction fluid damping member is adjusted by the magnetic damping adjusting device to reduce the noise of the motor.

[0014] Preferably, the motor is a direct current motor, and the noise is commutation noise.

[0015] When the motor is started or during the operation of the motor, the following control for reducing the noise of the motor is performed.

[0016] R01: detecting the rotating speed of the motor;

[0017] R02: obtaining the commutation frequency f at the rotating speed of the motor;

[0018] R03: detecting the noise data of the motor, extracting the noise peak value A in the range of f±Δf, wherein Δf is a first preset frequency value; if A≥a first preset value X, the next step R04 is performed, otherwise, the step R01 is returned to continue detection.

[0019] R04: adjusting the magnetic field around the first magnetic induction fluid damping member and / or the second magnetic induction fluid damping member to reduce the noise of the motor.

[0020] Preferably, the magnetic damping adjusting device further comprises an adjustable resistor, the current passing through the first coil and / or the second coil can be adjusted by adjusting the resistance value of the adjustable resistor, and the magnetic field around the first magnetic induction fluid damping member and / or the second magnetic induction fluid damping member can be adjusted, and the step R04 "adjusting the magnetic field around the first magnetic induction fluid damping member and / or the second magnetic induction fluid damping member by the magnetic damping adjusting device to reduce the noise of the motor" comprises:

[0021] T01: adjusting the resistance value of the adjustable resistor for multiple times, and synchronously calculating the loss factor b of the noise and the corresponding resistance value;

[0022] T02: obtaining the resistance value corresponding to the maximum loss factor, and adjusting the resistance value of the adjustable resistor to the resistance value corresponding to the maximum loss factor.

[0023] Preferably, the loss factor is calculated by the formula wherein F is the peak frequency in the range of f±Δf, F0 is the half width of the resonance curve, that is, the frequency width at which the noise peak corresponding to the frequency F decreases by a first preset noise value, and Δf is a first preset frequency value.

[0024] Preferably, the step T01 of adjusting resistance value of the adjustable resistor comprises: firstly adjusting the resistance value of the adjustable resistor to the maximum value, and then reducing the resistance value by the first preset resistance value k each time from the maximum value, the first preset resistance value k is 1 / N of the maximum resistance value, N>=2, N is a natural number, until the resistance value is adjusted to 0.

[0025] By the above setting, the motor noise such as the commutation noise of the DC motor can be reduced. The application can identify the commutation noise, adjust the variable damping vibration reduction device to control the vibration transmission of the rotor of the motor, reduce the vibration of the motor set, improve the commutation noise problem of the motor set, and improve the quality of the motor set.

[0026] It should be understood that the foregoing general description and the following detailed description are only examples and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0027] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

[0028] Figure 1 Schematic diagram of the motor of the embodiment of the application.

[0029] Figure 2 Figure 1 Schematic diagram of the section A-A of the motor.

[0030] Figure 3 Figure 1 Schematic diagram of the section B-B of the motor.

[0031] Figure 4 Figure 3 Schematic diagram of the section C of the motor.

[0032] Figure 5 Figure 4 Schematic diagram of the section D-D of the motor.

[0033] Figure 6 Schematic diagram of the magnetic induction fluid damping piece of the embodiment of the application.

[0034] Figure 7 Schematic diagram of the coil of the magnetic induction fluid damping piece of the embodiment of the application.

[0035] Figure 8 Schematic diagram of the control principle of the magnetic damping adjusting device of the embodiment of the application.

[0036] Figure 9 Schematic diagram of the control of the DC motor of the embodiment of the application.

[0037] Figure 10 Magnetic damping adjustment schematic diagram of the embodiment of the application.

[0038] Wherein: 1-motor, 2-rotor, 3-stator, 4-housing, 51-inner ring, 52-outer ring, 53-roller, 61-first magnetic induction fluid damping piece, 62-second magnetic induction fluid damping piece, 63-rubber layer, 64-magnetorheological fluid layer, 65-induction coil, 7-end cover, 8-gasket. DETAILED DESCRIPTION

[0039] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings. Example embodiments, however, can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. Like reference numerals refer to like elements throughout the several views of the drawings, and the repeated description is omitted.

[0040] Moreover, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the

[0041] It should be understood that although the terms first, second, third, etc. can be used herein to describe various structures, these structures should not be limited by these terms. These terms are used only to distinguish one structure from another. Thus, a first structure discussed below could be termed a second structure without departing from the teachings of the present disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0042] Those skilled in the art can understand that the modules or flows in the drawings are only schematic diagrams of the example embodiments, and are not necessarily essential for implementing the present disclosure, and therefore cannot be used to limit the protection scope of the present disclosure.

[0043] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Figures 1-10 The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0044] Embodiments of the present invention provide a motor 1 and a control method thereof, preferably a DC motor 1 with a vibration damping device designed to address resonant noise such as commutation noise of the DC motor 1. The motor 1 includes a magnetic damping adjustment device, which can optimize the commutation noise of the unit by suppressing the vibration transmission in the commutation frequency range of the rotor 2 of the motor 1.

[0045] like Figures 1-5 As shown, the motor 1 includes: a housing 4, a rotor 2, a shaft for the rotor 2, and a bearing that mates with the shaft. The bearing includes an inner ring 51, rollers 53, and an outer ring 52. The outer ring 52 of the bearing is fixed to the housing 4, and the inner ring 51 of the bearing is fixed to the shaft. It also includes a magnetic damping adjustment device. The magnetic damping adjustment device includes a first magnetic induction fluid damping element 61, which is disposed between the shaft and the inner ring 51 of the bearing; and / or, the magnetic damping adjustment device includes a second magnetic induction fluid damping element 62, which is disposed between the outer ring 52 of the bearing and the housing 4. The motor 1 also includes an end cover 7 and a gasket 8, wherein the bearing may be a rolling bearing.

[0046] A first magnetic induction fluid damping element 61 is provided between the rotor 2 of motor 1 and the inner ring 51 of bearing, and a second magnetic induction fluid damping element 62 is provided between the housing 4 of motor 1 and the outer ring 52 of bearing to suppress the transmission of vibration of the rotor 2 of motor 1 caused by unbalanced electromagnetic force to other parts of motor 1, thereby reducing noise such as commutation noise.

[0047] The rotating shaft has a first groove, and a first magnetic induction fluid damping element 61 is disposed in the first groove. The first groove is a first annular groove, and the first magnetic induction fluid damping element 61 is a first annular structure, which is disposed in the first groove. The depth of the first groove is approximately equal to the thickness of the first annular structure.

[0048] The housing 4 is provided with a second groove, and the second magnetic induction fluid damping element 62 is disposed in the second groove.

[0049] The second groove is a second annular groove, and the second magnetic induction fluid damping element 62 is a second annular structure, which is arranged in the second groove. The depth of the second groove is greater than the thickness of the second annular structure, and part of the outer ring 52 is located in the second annular groove.

[0050] like Figures 6-8 As shown, the magnetic induction fluid damping component includes a hollow rubber layer 63 and a magnetorheological fluid layer 64 filled therein. The viscosity of the magnetorheological fluid is affected by the strength of the current flowing through it, which will result in different damping forces and damping torques, thus having different vibration reduction effects on the system.

[0051] The magnetic damping adjusting device comprises a magnetic induction fluid damping element, an adjustable resistor, an induction coil 65, and a power supply, which can be a DC power supply. The induction coil 65 comprises a first coil and a second coil, and by changing the current of the first coil, different magnetic fields can be provided to the first magnetic induction fluid damping element 61; by changing the current of the second coil, different magnetic fields can be provided to the second magnetic induction fluid damping element 62.

[0052] As Figure 9 , 10, the embodiment of the application further provides a control method of the motor 1, which comprises the following control: starting the magnetic damping adjusting device, adjusting the magnetic field around the first magnetic induction fluid damping element 61 and / or the second magnetic induction fluid damping element 62, and reducing the noise of the motor 1.

[0053] In addition, the embodiment of the application further provides a magnetic induction variable magnetic damping adjusting device and a control method, which is reversible and controllable in the adjusting mode, and the optimal damping state can be found by calculating and comparing the noise loss factors in different damping states, so that the damping device achieves the optimal damping effect.

[0054] The control method of the application: includes the detection and judgment of the motor 1 control system on the commutation noise and the adjustment of the damping device according to the judgment conclusion two processes. The damping device adopts the magnetic induction fluid damping element, and is controlled and adjusted by the magnetic induction controller. After receiving a certain instruction, the magnetic damping adjusting device adjusts the current strength flowing through the magnetic induction fluid damping element, so as to realize the damping value control of the magnetic induction fluid damping.

[0055] The motor 1 is a DC motor 1, and the noise is a commutation noise. When the motor starts or during the operation of the motor, the following control for reducing the noise of the motor is performed:

[0056] R01: detecting the rotating speed of the DC motor 1; the motor set starts to operate, and the system starts to detect the sensor to obtain the rotating speed value of the motor 1.

[0057] R02: obtaining the commutation frequency f at the rotating speed of the DC motor 1; the formula is

[0058] The commutation frequency of the motor 1 at the rotating speed is calculated, wherein c is the least common multiple of the slot number of the rotor 2 and the pole number of the stator 3 of the motor 1, and n is the rotating speed of the motor 1 (unit: rpm). For example, the commutation frequency of an 8-pole 12-slot DC motor 1 at 1000 rpm is 1000*24 / 60 Hz.

[0059] R03: detecting the noise data of the motor 1; extracting the noise peak value A in the range of the commutation frequency f±Δf, and Δf is the first preset frequency value; if A≥the first preset value X, the next step is executed, otherwise, the motor 1 continues to operate normally.

[0060] The noise data of the unit is collected by the noise sensor, the system extracts the noise peak value A within the commutation frequency point ± 5Hz, the unit is dB, and it is judged whether A exceeds the commutation noise limit value X dB. When A < X, the unit can operate normally, there is no current in the magnetic induction variable damping, the magnetorheological fluid shows the characteristics of low viscosity and strong fluidity, and the damping value is fixed and unchanged;

[0061] When A ≥ X, it is determined that the commutation noise is not acceptable, the unit automatically starts the magnetic damping adjusting device, the current passes through the magnetic induction variable damping, the magnetorheological fluid shows the characteristics of high viscosity and low fluidity, and the damping value changes with the current.

[0062] The magnetic damping adjusting device further comprises an adjustable resistor, and the current of the first coil and / or the second coil can be adjusted by adjusting the resistance value of the adjustable resistor, so as to adjust the magnetic field of the magnetic damping member.

[0063] The step R04 of "starting the magnetic damping adjusting device, starting the magnetic damping adjusting device, adjusting the magnetic field around the first magnetic induction fluid damping member 61 and / or the second magnetic induction fluid damping member 62, and reducing the noise of the motor 1" comprises: T01: adjusting the resistance value of the adjustable resistor multiple times, and synchronously calculating the loss factor b of the noise and the corresponding resistance value;

[0064] T02: obtaining the resistance value corresponding to the maximum loss factor, and adjusting the resistance value of the adjustable resistor to the resistance value corresponding to the maximum loss factor.

[0065] Specifically, U01: adjusting the resistance value of the adjustable resistor to the maximum value;

[0066] U02: detecting the noise data of the unit;

[0067] U03: calculating the loss factor b of the noise;

[0068] The motor 1 starts the magnetic damping adjusting device, the damping adjusting circuit power supply is started, the initial state, the resistance value of the adjustable resistor in series with the magnetic induction variable damping is the maximum value, the current in the magnetic induction variable damping is the minimum value, the system synchronously detects the resonance peak frequency F and the half width F0, and the noise loss factor b is calculated by the formula F is the resonance peak frequency, that is, the commutation frequency f±Δf such as the peak frequency within 5Hz, F0 is the half width of the resonance curve, that is, the frequency width at the point where the noise peak corresponding to the frequency F decreases by a first preset noise value such as 3dB, the system records the current resistance value and the loss factor, and Δf is a first preset frequency value.

[0069] U04: adjusting the resistance value of the adjustable resistor multiple times from large to small, and synchronously calculating the loss factor b of the noise and the corresponding resistance value;

[0070] The system synchronously calculates and records the loss factor and the resistance value. Until the adjustable resistance value is zero, the system takes the maximum value of all loss factors, and when the loss factor reaches the maximum value, the noise reduction degree reaches the maximum degree, and the corresponding resistance value is the optimal resistance value. The resistance value of the adjustable resistance is adjusted to the resistance value corresponding to the maximum loss factor.

[0071] U05: obtaining the resistance value corresponding to the maximum loss factor;

[0072] U06: adjusting the resistance value of the adjustable resistance to the resistance value corresponding to the maximum loss factor.

[0073] The way of calculating the loss factor in steps U03 and U04 is: calculating the noise loss factor b by the formula, wherein F is the peak frequency in the commutation frequency f±Δf range, and is the half width of the resonance curve, that is, the frequency width at which the noise peak corresponding to the frequency F decreases by a first preset noise value.

[0074] Step U04: adjusting the resistance value of the adjustable resistance from large to small multiple times includes: adjusting the resistance value from the maximum by a first preset resistance value k each time, the first preset resistance value k is 1 / N of the maximum resistance value, N≥2, N is a natural number, and the resistance value is adjusted to 0 until the resistance value is adjusted to 0. The controller adjusts the variable resistance from large to small, and the resistance value is reduced by k each time, k refers to the adjustment amount of the variable resistance (an integer divisor of the maximum resistance value of the variable resistance), which is determined by the maximum resistance value of the variable resistance, and is preferably 1 / 10-1 / 15 of the maximum resistance value.

[0075] The application can set the thickness of the magnetic induction variable damping according to the specific motor 1 structure, and can flexibly modify the control system of the application for reducing other resonance noises except commutation noise, and can improve the noise problem caused by resonance of the same type. The above solutions are all within the protection scope of the application.

[0076] Advantages:

[0077] The application can effectively reduce the noise of the motor, especially the commutation noise of the DC motor. The application preferably controls the vibration transmission of the motor rotor by identifying the commutation noise and adjusting the variable damping vibration reduction device, thereby reducing the vibration of the motor set. The application preferably adjusts the resistance value of the adjustable resistance by gradually adjusting the resistance value of the adjustable resistance, combines noise detection, obtains the loss factor, adjusts the adjustable resistance according to the resistance value corresponding to the maximum loss factor, can significantly improve the commutation noise problem of the motor set, and improves the operation quality of the motor set.

[0078] The exemplary embodiments of the present disclosure are specifically shown and described above. It should be understood that the present disclosure is not limited to the detailed structure, arrangement or implementation method described herein; on the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims.

Claims

1. An electric machine (1) comprising: The housing (4), the end cover, the rotor (2), the rotating shaft of the rotor (2), and the bearing matched with the rotating shaft, wherein the bearing comprises an inner ring (51) and an outer ring (52), the outer ring (52) of the bearing is fixed with the housing (4), and the inner ring (51) of the bearing is fixed with the rotating shaft; characterized in that the magnetic damping adjusting device is further included. The magnetic damping adjusting device comprises: A first magnetic induction fluid damping element (61) arranged between the rotating shaft and the inner ring (51) of the bearing; A second magnetic induction fluid damping element (62) arranged between the outer ring (52) of the bearing and the housing (4); The first magnetic induction fluid damping element and the second magnetic induction fluid damping element are configured to reduce the noise of the motor by adjusting the magnetic field around the first magnetic induction fluid damping element and / or the second magnetic induction fluid damping element; The motor is a direct current motor, and when the motor is started or during the operation of the motor, the following control for reducing the noise of the motor (1) is performed: R01: detecting the rotating speed of the motor (1); R02: obtaining the commutation frequency f at the rotating speed of the motor (1); R03: detecting the noise data of the motor (1), extracting the noise peak value A within the range of f±Δf, and Δf is a first preset frequency value; if A≥the first preset value X, the next step R04 is executed, otherwise, returning to step R01 for continuous detection; R04: adjusting the magnetic field around the first magnetic induction fluid damping element (61) and / or the second magnetic induction fluid damping element (62) to reduce the noise of the motor (1).

2. The electric machine (1) according to claim 1, characterized in that: The rotating shaft is provided with a first groove, and the first magnetic induction fluid damping element (61) is arranged in the first groove.

3. The electric machine (1) according to claim 2, characterized in that: The first groove is a first annular groove, and the first magnetic induction fluid damping element (61) is a first annular structure and is annularly arranged in the first groove.

4. The electric machine (1) according to claim 3, characterized in that: The depth of the first groove is equal to the thickness of the first annular structure.

5. The electric machine (1) according to claim 1, characterized in that: The housing (4) is provided with a second groove, and the second magnetic induction fluid damping element (62) is arranged in the second groove.

6. The electric machine (1) according to claim 5, characterized in that: The second groove is a second annular groove, and the second magnetic induction fluid damping element (62) is a second annular structure and is annularly arranged in the second groove, the depth of the second groove is greater than the thickness of the second annular structure, and part of the outer ring (52) is located in the second annular groove.

7. The electric machine (1) according to claim 1, characterized in that: The magnetic damping adjusting device further comprises a first coil, and the magnetic field around the first magnetic induction fluid damping element (61) can be adjusted by changing the current passing through the first coil; And / or, the magnetic damping adjusting device further comprises a second coil, and the magnetic field around the second magnetic induction fluid damping element (62) can be adjusted by changing the current passing through the second coil.

8. A method of controlling an electric machine (1), characterized in that: The motor (1) comprises: a housing (4), a rotor (2), a rotating shaft of the rotor (2), a bearing matched with the rotating shaft, the bearing comprising an inner ring (51) and an outer ring (52); the outer ring (52) of the bearing is fixed together with the housing (4), and the inner ring (51) of the bearing is fixed together with the rotating shaft; the motor further comprises a magnetic damping adjusting device; the magnetic damping adjusting device comprises: a first magnetic induction fluid damping piece (61), the first magnetic induction fluid damping piece (61) being arranged between the rotating shaft and the inner ring (51) of the bearing; a second magnetic induction fluid damping piece (62), the second magnetic induction fluid damping piece (62) being arranged between the outer ring (52) of the bearing and the housing (4); the first magnetic induction fluid damping piece and the second magnetic induction fluid damping piece are configured to reduce the noise of the motor by adjusting the magnetic field around the first magnetic induction fluid damping piece and / or the second magnetic induction fluid damping piece; Wherein, when the motor starts or during the operation of the motor, the following control for reducing the noise of the motor (1) is performed: R01: detecting the rotating speed of the motor (1); R02: obtaining the commutation frequency f at the rotating speed of the motor (1); R03: detecting the noise data of the motor (1), extracting the noise peak value A within the range of f±Δf, Δf being a first preset frequency value; if A≥a first preset value X, the next step R04 is executed, otherwise, returning to step R01 to continue detecting; R04: adjusting the magnetic field around the first magnetic induction fluid damping piece (61) and / or the second magnetic induction fluid damping piece (62) to reduce the noise of the motor (1).

9. The control method according to claim 8, characterized in that: The magnetic damping adjusting device further comprises: a first coil, by changing the current of the first coil, the magnetic field around the first magnetic induction fluid damping piece (61) can be adjusted; the magnetic damping adjusting device further comprises: a second coil, by changing the current passing through the second coil, the magnetic field around the second magnetic induction fluid damping piece (62) can be adjusted; The magnetic damping adjusting device further comprises an adjustable resistor, by adjusting the resistance value of the adjustable resistor, the current passing through the first coil and / or the second coil can be adjusted, and then the magnetic field around the first magnetic induction fluid damping piece (61) and / or the second magnetic induction fluid damping piece (62) can be adjusted; Wherein, the step R04 adjusts the magnetic field around the first magnetic induction fluid damping piece (61) and / or the second magnetic induction fluid damping piece (62) to reduce the noise of the motor (1) comprises: T01: adjusting the resistance value of the adjustable resistor multiple times, and synchronously calculating the loss factor b of the noise and the corresponding resistance value; T02: obtaining the resistance value corresponding to the maximum loss factor, and adjusting the resistance value of the adjustable resistor to the resistance value corresponding to the maximum loss factor.

10. The control method according to claim 9, characterized in that: The loss factor is calculated in the following manner: from the formula , the noise loss factor b is calculated, wherein F is the peak frequency in the commutation frequency f±Δf range, is the half-width of the resonance curve, that is, the frequency width at which the noise peak corresponding to the frequency F drops by a first preset noise value, and Δf is the first preset frequency value.

11. The control method according to claim 10, characterized in that: The step T01 "adjusting the resistance value of the adjustable resistor multiple times" comprises: first adjusting the resistance value of the adjustable resistor to the maximum value, then adjusting the resistance value by a first preset resistance value k each time from the maximum value, the first preset resistance value k being 1 / N of the maximum resistance value, N≥2, N being a natural number, until the resistance value is adjusted to 0.

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