340 results about "Motor noise" patented technology

The embodiment of the invention relates to the technical field of fans, and particularly discloses an active noise reduction fan which comprises a shell which is a portable shell, a cavity is formed in the shell, and an air inlet and an air outlet which are communicated with each other are formed in the two ends of the shell respectively; the fan assembly is arranged in the cavity and used for rotating to generate wind pressure so that air can be sucked in from the air inlet, passes through the cavity and then is blown out from the air outlet; the noise reduction assembly is arranged in the cavity and used for collecting noise signals inside and outside the cavity in real time when the fan assembly operates and sending out noise reduction signals according to the noise signals; wherein the noise reduction signal is a dynamic comprehensive noise signal including air inlet noise, air outlet noise, fan blade noise and / or motor noise. Through reasonable design of functions of the noise reduction assembly, active noise control is performed on the noise signal by using the noise reduction signal, and the noise level during operation of the fan is reduced.

The invention discloses a motor abnormal sound detection method and system based on contact acquisition and small sample learning, and the method comprises the steps: directly coupling a motor housing through a contact vibration sensor, collecting an original vibration signal, and generating an anti-interference vibration signal; inputting the anti-interference vibration signal into a nonlinear resonance enhancement module to generate an enhanced sound signal; performing wavelet packet decomposition on the enhanced sound signal, extracting a multi-scale frequency band energy entropy, and generating a motor abnormal sound feature matrix by combining singular value decomposition dimension reduction; on the basis of a dynamic weight distribution element learning algorithm, a small number of normal samples and abnormal samples are utilized to construct an abnormal sound classification model; and inputting the motor abnormal sound characteristic matrix into an abnormal sound classification model, detecting transient abnormality through a sliding window time sequence matching algorithm, and outputting an abnormal sound judgment result. According to the embodiment of the invention, high-precision and low-false-alarm motor abnormal sound detection under complex working conditions can be realized.

The ducted unmanned aerial vehicle noise reduction device is characterized in that the ducted unmanned aerial vehicle noise reduction device comprises a ducted noise reduction structure and a supporting structure, the ducted noise reduction structure comprises an outer duct and an inner duct, the outer duct comprises an outer duct back plate, an outer duct cavity and an outer duct bent micro-perforated plate acoustic liner, and the supporting structure comprises an inner duct back plate and an outer duct bent micro-perforated plate acoustic liner. The inner duct comprises an inner duct back plate, an inner duct cavity and an inner duct bent micro-perforated plate acoustic liner, and the inner duct is placed in the outer duct and connected with the outer duct through a supporting structure. The supporting structure comprises a supporting strip and a supporting seat, the supporting strip is connected with the bottom of the outer duct, and the supporting seat is located at the central axis of the outer duct and connected with the inner duct. Due to the fact that the outer duct and the inner duct form a noise reduction structure based on the bent micro-perforated plate acoustic liner, most of motor noise and noise generated during rotation of the propeller can be effectively absorbed, and the noise reduction function is achieved. On the premise that the weight and the size are not increased too much, the purpose of reducing the noise of the propellers and the motors of the ducted unmanned aerial vehicle is achieved, and good application value is achieved.

The invention provides a high-precision identification method and system for a noise source of an asynchronous motor and a storage medium, and relates to the technical field of asynchronous motors. Related parameters of an inner ring, an outer ring, a retainer and a rolling body of a bearing of the motor are collected, and abnormal frequency analysis is carried out on the inner ring, the outer ring, the retainer and the rolling body; a bearing inner ring abnormal frequency index, a bearing outer ring abnormal frequency index, a rolling body abnormal frequency index and a rigidity abnormal frequency index which reflect abnormal frequencies of an inner ring, an outer ring, a retainer and a rolling body respectively are output, meanwhile, vibration signals are collected for the motor, frequency domain signals are generated after the vibration signals are processed, a frequency spectrum is obtained, and the frequency spectrum is calculated. And generating a rolling body anomaly evaluation index, a rigidity anomaly evaluation index, a bearing inner ring evaluation index and a bearing outer ring anomaly evaluation index which respectively reflect the anomaly degrees of different parts through the relationship of the frequency amplitude and in combination with the anomaly frequency index, so as to assist a worker in judging a specific bearing fault part.

Embodiments of the present disclosure relate to a method, device and medium for reducing noise of a motor, the motor being a permanent magnet synchronous motor based on vector control, the method comprising performing interruptions on the motor at a first frequency and a second frequency, respectively, based on a predetermined timing sequence; when the interruption is executed on the second frequency, performing filtering processing on a vector control PWM duty ratio signal of the motor by using a multi-order weighted sliding mean filter so as to filter out a high-frequency harmonic component; performing compensation of the target phase compensation amount on the rotor angle of the motor when the interruption is performed on the first frequency; and performing space vector modulation on the interrupted output of the vector control PWM duty cycle signal of the motor, thereby obtaining the PWM duty cycle signal for reducing the noise of the motor.

The present application provides a simulation method, electronic device and storage medium for multi-speed motor noise, and relates to the field of simulation technology. The method comprises responding to a multi-speed motor noise analysis request for a target motor model, determining the speed quantity value and frequency point quantity value in a load file uploaded by a user, the degree of freedom and field point quantity value of an acoustic solution configured by the user, and the number of CPU parallel cores of an execution device; inputting the speed quantity value and frequency point quantity value, the degree of freedom and field point quantity value and the number of CPU parallel cores into a pre-trained classification model to obtain a classification result output by the classification model; selecting the optimal solution indicated by the classification result to perform multi-speed noise simulation, obtaining the corresponding noise simulation results at multiple speeds of the target motor model, and integrating the pre-processing, solver and post-processing of the motor multi-speed analysis to improve the environmental adaptability and computational efficiency of the multi-speed motor noise simulation.

The utility model provides a motor noise reduction housing with low noise, and relates to the technical field of motor housings. The motor comprises a motor housing, the interior of the motor housing is rotatably connected with an output rotating shaft, the exterior of the output rotating shaft is provided with a heat dissipation mechanism, the heat dissipation mechanism comprises a rubber gasket fixedly connected with the output rotating shaft, and the outer surface of the rubber gasket is fixedly connected with a heat dissipation lantern ring. Through the arrangement of the output rotating shaft, the rubber gasket, the heat dissipation lantern ring, the heat dissipation fan blades and the reinforcing rods, the output rotating shaft rotates to drive the heat dissipation lantern ring to rotate, and the heat dissipation lantern ring drives the heat dissipation fan blades to rotate, so that heat in the motor shell is discharged out of the device, and normal operation of the motor is prevented from being influenced by over-high temperature in the motor shell; a rubber gasket and a reinforcing rod can keep the heat dissipation lantern ring stable in the rotating process, the situation that the heat dissipation lantern ring shakes to generate friction with the output rotating shaft is avoided, and noise generated by friction between the heat dissipation lantern ring and the output rotating shaft in the heat dissipation process is reduced.

The invention discloses a stator assembly, a motor and a household appliance, and relates to the technical field of motors. The stator assembly comprises a stator iron core and a plastic coating part, the stator iron core is coated with the plastic coating part, the plastic coating part is provided with a spigot boss on the end face of the opening part, and the spigot boss is matched with the end cover in an abutting mode. The height of the stator core is h0, the distance between the first end face of the opening part and the second end face of the stator core is h, when h0 is larger than or equal to 20 mm, h = h0 * 0.5 + S1, and S1 is larger than or equal to 6 mm and smaller than or equal to 10 mm. When h0 is smaller than 20 mm, h = h0 * 0.65 + S2, and S2 is larger than or equal to 5 mm and smaller than or equal to 8 mm. The value of h is designed according to the calculation result of the formula, so that the relationship between the material consumption of the plastic coating part and the noise of the motor can be balanced, the noise of the motor meets the requirement, the material consumption of the plastic coating part can be in a proper range, and the production cost is reduced.

The invention discloses a rotor punching sheet, a motor, a compressor and refrigeration equipment, the rotor punching sheet comprises a punching sheet body, the end face of the punching sheet body is provided with a plurality of structure groups, each structure group comprises a first magnetic isolation groove, a magnetic isolation bridge and a mounting groove, the mounting groove is internally provided with a permanent magnet, and the length of the permanent magnet is w1; a mounting groove is formed in the punching sheet body, a first magnetic isolation groove is formed between each of two ends of the mounting groove and the outer peripheral surface of the punching sheet body, so that a magnetic isolation bridge is formed between each first magnetic isolation groove and the outer peripheral surface of the punching sheet body, the length of the magnetic isolation bridge is w2, and the relation range of w1 and w2 is that w2 / w1 is greater than or equal to 0.3 and less than or equal to 0.6. According to the technical scheme, on the premise that the mechanical structure strength of the rotor is guaranteed, the optimal pole-arc coefficient of the motor can be achieved, the no-load back electromotive force harmonic distortion rate, the cogging torque and the torque pulsation of the motor are reduced, the noise vibration of the motor is reduced, and the magnetic leakage is reduced, so that the performance of the motor is improved.

The invention discloses a fault prediction method and system based on motor noise, and the method comprises the steps: 1, defining a sampling time length, obtaining the noise in the sampling time length, and carrying out the framing operation to generate a noise frame sequence; 2, extracting spectrum feature data of each frame of noise in the noise frame sequence to generate a noise feature sequence; 3, inputting the noise feature sequence into a self-attention neural network model, and outputting a noise representation sequence by the self-attention neural network model; 4, acquiring a set composed of samples of the standard fault noise of the motor, generating a feature vector of each sample, performing cross attention mechanism calculation with the noise representation sequence, and generating a judgment representation of a fault corresponding to each sample; and 5, inputting the judgment representation of the fault corresponding to each sample into the feedforward neural network model to generate the judgment probability of each fault, thereby realizing accurate judgment of the working state of the motor, and simultaneously judging multiple fault types under the condition of not increasing the calculation amount.

The invention discloses a noise reduction structure for a high-speed motor, and belongs to the technical field of high-speed motors, the noise reduction structure comprises a placing frame and a noise reduction mechanism, the noise reduction mechanism comprises a sealing cover, a fixing plate, a supporting assembly, a sound insulation assembly, a fixing assembly and a heat dissipation assembly; a sealing cover is arranged at the top end of the containing frame, a motor can be placed on the inner side of the containing frame, the two fixing assemblies fix the position of the motor through the driving assembly, vibration generated when the motor works can be relieved, the vibration noise of the motor is reduced, a rotating shaft of the motor can be limited through the supporting assembly, and stable rotation of the rotating shaft of the motor is kept; heat generated by the motor during working can be discharged out of the placement frame through the heat dissipation assembly, the situation that heat dissipation holes are formed in the placement frame, and noise propagation is caused is avoided, a sealed space can be formed through the sealing cover and the placement frame, motor noise propagation can be effectively isolated through the sound insulation assembly, and sound insulation and noise reduction operation is achieved.

The utility model discloses a vibrating water pump, and belongs to the technical field of water pumps. The technical problems that an existing water pump is large in size, complex in structure and large in motor operation noise are solved. According to the technical scheme, the water purifier is characterized by comprising a shell, a one-way valve, a vibrator, a diaphragm and a rigid support, the vibrator is installed on the diaphragm to provide diaphragm vibration energy, the diaphragm is fixed in the shell through the rigid support and divides the shell into a water inlet area and a water outlet area, and the one-way valve is further fixed to the rigid support; the one-way valve is communicated with the water inlet area and the water outlet area and keeps water flowing into the water outlet area from the water inlet area in a one-way mode. The water purifier has the advantages of being long in service life, easy to overhaul, adjustable in power and convenient to use.

The invention discloses an external rotor permanent magnet synchronous motor noise prediction method, system and device and a medium, and relates to the technical field of motor noise, and the method comprises the steps: building a two-dimensional electromagnetic model of an external rotor permanent magnet synchronous motor ERPMSM; analyzing the spatial distribution and frequency characteristics of the electromagnetic force acting on the surface of the permanent magnet through the two-dimensional electromagnetic model to obtain the electromagnetic force; establishing a three-dimensional structure model of the ERPMSM, and loading the electromagnetic force into the three-dimensional structure model in a nodal force form to obtain a nodal force acting on the surface of the permanent magnet in a three-dimensional space; based on the three-dimensional structure model and the nodal force, the radial vibration acceleration of the ERPMSM outer rotor is calculated by adopting a mode superposition method; and taking the radial vibration of the outer rotor as an acoustic boundary condition, and predicting the noise of the ERPMSM by using an acoustic boundary element method.

The invention discloses a motor noise detection method and system based on waveform analysis, and relates to the related field of motor fault diagnosis, and the method comprises the steps: carrying out the time domain collection of an original noise signal during the operation of a motor, obtaining an original waveform signal, carrying out the Fourier transform of the original waveform signal, extracting the spectrum characteristics, and obtaining the spectrum energy distribution; performing threshold segmentation on the frequency spectrum energy distribution, screening out motors which meet a preset quality standard but have preset abnormal indications, and obtaining critical qualified motors; extracting an original waveform signal of the critically qualified motor, and extracting a transient impact component from the original waveform signal to obtain a transient feature; and matching the transient feature with an early fault mode in a pre-constructed fault feature library, and outputting a potential fault detection result. The technical problem that the current qualified motor with potential faults cannot be identified in the existing motor noise detection is solved, and the technical effect of accurately identifying the qualified motor with the potential faults is achieved.

The invention discloses a motor production line defect detection and diagnosis method, and belongs to the technical field of production quality optimization, and the method specifically comprises the steps: collecting the rotating speed of a motor during operation, and recording the weight of an object carried by the motor each time; noise generated when the motor works is collected, environment noise is filtered, and motor noise is obtained; the method comprises the following steps: dividing the weight of an object needing to be carried by a motor into a plurality of grades, respectively carrying out linear fitting on the change relation of motor noise along with the rotating speed and the change relation of motor noise along with the load under different grades, and calculating the fitting degree of the noise and the rotating speed and the fitting degree of the noise and the load after linear fitting; when the fitting degree of the noise and the load is high, calculating the maximum load of the motor by adjusting the load, and when the fitting degree of the noise and the rotating speed is high, calculating the maximum rotating speed of the motor by adjusting the rotating speed of the motor; and the motor with the difference value between the maximum load and the maximum rotating speed and the set value larger than a preset threshold value is judged to be unqualified.

The invention discloses a frequency converter, a current sampling circuit thereof and a three-phase current sampling method of a motor, the frequency converter is suitable for driving the motor in a compressor, and the current sampling circuit comprises a single-resistance sampling unit configured to perform current sampling at a voltage effective vector moment so as to obtain three-phase current of the motor; the multi-resistance sampling unit is configured to perform current sampling at a voltage zero vector moment so as to obtain three-phase current of the motor; and the switching control unit is configured to acquire parameters of the motor, determine a switching index according to the parameters of the motor, and select one of the single-resistor sampling unit and the multi-resistor sampling unit to perform current sampling based on the switching index. The current sampling circuit can solve the problems that the noise of the motor is large due to single-resistor sampling and the performance of the motor is reduced due to multi-resistor sampling, so that the performance of the motor is improved.

The invention belongs to the technical field of motors, and particularly discloses a variable-air-gap axial flux permanent magnet synchronous motor which comprises a machine shell, a stator module, a rotor module and an adjusting module. The rotor module comprises a rotating shaft, a rotor support and magnetic steel arranged on the rotor support, and the rotor support is fixedly arranged on the rotating shaft in a sleeving mode. The two stator modules are arranged on the two sides of the rotor support respectively. Each stator module comprises a stator and a stator support. The stator module and the rotor module are arranged in the casing, and the casing is provided with a through hole for a rotating shaft of the rotor module to pass through, so that one end of the rotating shaft of the rotor module extends out of the casing; and the adjusting module is used for synchronously adjusting the axial distance between the two stator modules and the rotor module so as to adjust air gaps on two sides of the rotor module. The size of air gaps on two sides of the rotor can be adjusted during assembly, so that the balance of the air gaps on the two sides is ensured, the noise of the motor is reduced, the size of the air gaps on the two sides can be effectively adjusted during operation, the efficiency of the motor is improved, and the constant-power rotating speed range of the motor is greatly widened.

The utility model belongs to the technical field of rotors, and particularly relates to a rotor punching sheet, a rotor, a motor, a power assembly and a vehicle. The rotor punching sheet comprises a plurality of magnetic poles arranged along the circumferential direction of the rotor punching sheet, each magnetic pole is provided with a magnetic steel groove group, a first groove and a slotted hole, each magnetic pole is provided with a d axis and a q axis, the magnetic poles are symmetrical about the d axis, and the adjacent magnetic poles are symmetrical about the q axis; the first groove is arranged at the intersection of the outer edge of the magnetic pole and the d shaft, the first groove is arranged at the outer side of the magnetic steel groove group in the radial direction of the rotor punching sheet, and the q shaft passes through the groove hole. According to the utility model, through the combination of the first grooves on the d-axis and the slotted holes on the q-axis, magnetic field forces in the tangential direction and the radial direction brought by a harmonic magnetic field can be reduced, lower air gap flux density and harmonic content are obtained, the torque pulsation and the radial force of the rotor punching sheet are reduced, and the purpose of reducing motor noise is achieved.

The invention discloses a stator assembly, a motor and a household appliance, and relates to the technical field of motors. The stator assembly comprises a stator iron core and a plastic coating part, the stator iron core is coated with the plastic coating part, and the plastic coating part is provided with a spigot boss on the end face of the opening part. The height of the stator core is h0, the distance between the first end face of the opening part and the second end face of the stator core is h, when h0 is larger than or equal to 20 mm, h = h0 * 0.85 + S1, and S3 is larger than or equal to 3 mm and smaller than or equal to 5 mm. When h0 is smaller than 20 mm, h = h0 + S2, and S2 is larger than or equal to 3 mm and smaller than or equal to 5 mm. Under the condition that the axial size of the motor is not changed, the axial size is substituted into a corresponding formula to calculate the distance h from the first end face to the second end face, the strength and rigidity of the rear end of the plastic coating part are increased, the noise of the motor meets the requirement, meanwhile, the material consumption of the plastic coating part is within a proper range, the production cost is reduced, and the production efficiency is improved. And the relationship between the material consumption of the plastic coating part and the motor noise can be balanced.

The invention discloses a high-precision identification method and system for a noise source of an asynchronous motor, and relates to the technical field of asynchronous motor detection, and the method comprises the following steps: constructing a finite element model of a to-be-analyzed asynchronous motor, dividing the surface into a plurality of detection sub-regions, and carrying out the operation simulation of the finite element motor, analyzing vibration speed and sound pressure signal data of each sub-region, synchronously acquiring actual signals, calculating relative differences with simulation data, evaluating detection priorities by combining historical fault times, forming a detection sequence according to the priorities, and sequentially performing sound-vibration coherence analysis and coherence function calculation to obtain a sound-vibration coherence detection result; according to the method, noise frequency bands are classified into structural noise and air noise, order tracking analysis is performed on the structural noise obtained through classification, an amplitude stability index and an amplitude change gradient are calculated, automatic classification and identification of electromagnetic noise and mechanical noise are realized based on a preset threshold value, and the efficiency and accuracy of fault processing are remarkably improved.

The invention relates to the technical field of motor noise detection, and discloses a motor noise detector with a protection function, which comprises a detection frame, the surface of the detection frame is fixedly connected with a positioning ring, the bottom of the positioning ring is fixedly connected with supporting legs, the top of the positioning ring is fixedly connected with an electric push rod, and the output end of the electric push rod is fixedly connected with a pull rod. One end of the pull rod away from the electric push rod is fixedly connected with a top cover. When a to-be-detected motor is placed in the detection frame, the top cover is pushed to move towards the upper portion of the detection frame through connection of the electric push rod and the pull rod, after the top cover is separated from the top of the detection frame, the motor is placed in the clamping frame to make contact with the supporting component, and the supporting component is used for supporting and limiting the motor; and when the supporting part drives the motor to move towards the lower portion of the clamping frame, the supporting part pushes the clamping part to clamp and fix the motor, and the situation that the motor shakes in the noise detection process, and consequently the detection result has errors is avoided.

The invention discloses a motor, a compressor and refrigeration equipment, and relates to the technical field of refrigeration equipment, the number of poles of a rotor is 2P, the number of stator slots is Q, the longest distance between the slot bottom of a first magnetic adjusting slot and the circle center of a stator punching sheet is Ls, and the minimum inner diameter of the stator punching sheet is Di, the included angle between the connecting line of the point A and the circle center of the stator punching sheet and the center line in the length direction of the stator tooth is alpha, the two farthest end points of the tooth boot part along the circumferential direction of the stator punching sheet are respectively a point B and a point C, the included angle between the connecting line of the point B and the circle center of the stator punching sheet and the connecting line of the point C and the circle center of the stator punching sheet is beta, 0 degree < = 1.27 degrees, and 0 mm < = 0.2 mm. According to the technical scheme provided by the invention, the torque ripple of the motor is reduced, the noise of the motor is reduced, and the energy efficiency of the motor is improved.

The utility model relates to the technical field of motor noise detection, specifically provides a motor noise detection simulation load device and a motor noise detection device, and aims to solve the problem of inaccurate motor noise detection data in the prior art. In order to achieve the purpose, the motor noise detection simulation load device comprises a shell, a driving shaft, a transmission mechanism and a pressure adjusting mechanism, the driving shaft is rotatably arranged on the shell, one end of the driving shaft is connected with the driving end of the motor, the other end of the driving shaft is connected with the transmission mechanism, and the transmission mechanism is arranged in the shell; the pressure adjusting mechanism is arranged to be capable of making contact with the transmission mechanism and adjusting the acting force between the pressure adjusting mechanism and the transmission mechanism. According to the utility model, the actual load-carrying state of the motor can be simulated, no extra noise is generated like a fan, and the accuracy of motor noise detection is improved.

The application provides a fan coil motor noise reduction structure and method, an asynchronous motor and an air conditioning device. The structure adds an audio collector on the motor body and adds a movable assembly on the output shaft of the motor. The movable assembly drives the fan blade to move forward and backward along the output shaft, thereby improving the axial distance between the fan blade and the volute, so as to eliminate the peak noise in the preset range of about 300 Hz, and solve the problem that the electromagnetic noise in a specific frequency range cannot be eliminated when the motor operates in the prior art.

The application relates to the technical field of motor noise reduction, in particular to a motor noise reduction method for a portable fan. The handheld fan is internally provided with a driving motor. The method comprises the following steps: obtaining motor noise generated by the portable fan during operation; the motor noise comprises mechanical vibration noise, electromagnetic noise and aerodynamic noise of the driving motor; when the signal strength of the motor noise is greater than a preset strength threshold, generating a noise control instruction based on the motor noise; generating and emitting noise reduction signals for the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise based on the noise control instruction, so as to perform destructive interference on the motor noise. The motor operation noise level is reduced through active noise reduction and accurate processing of the fan motor noise.

The present disclosure relates to the field of noise reduction technologies, and specifically a motor noise control method and apparatus, a computer device and a storage medium are provided. The method includes: determining a current driving mode of a vehicle and a total torque required by the vehicle in the current driving mode; acquiring an electric drive noise distribution matrix of the vehicle in the current driving mode, where the electric drive noise distribution matrix includes correspondences among target motor noises, target motor speeds, and target motor torques of respective motors in the current driving mode; and distributing a torque of each motor according to the electric drive noise distribution matrix, where a sum of torques of the respective motors is equal to the total torque required by the vehicle.

The utility model discloses an outer rotor permanent magnet synchronous motor, which comprises a rotor component arranged in a motor shell, a stator component arranged in the rotor component, and a heat dissipation and noise reduction structure arranged on the stator component, the first bearing is arranged on one side of the outer rotor casing, and the plurality of permanent magnets are arranged in the outer rotor casing; the stator punching sheet group is arranged in the inner stator rack; the second bearing is arranged on one side of the stator punching sheet group; the plurality of stator teeth are arranged on the outer ring of the stator core, the stator accommodating grooves are arranged between the adjacent stator teeth, and the excitation windings are arranged in the stator accommodating grooves; in the heat dissipation and noise reduction structure, the heat dissipation part is arranged on the stator teeth, and the noise reduction part is arranged at one end of the stator teeth; the heat dissipation part comprises a first heat dissipation hole, a second heat dissipation hole and a third heat dissipation hole which are arranged on the stator teeth. According to the utility model, the heat radiation area of the stator surface can be effectively increased, convection heat radiation efficiency can be enhanced, stator temperature rise can be reduced, noise generation and transmission can be effectively weakened, and motor noise can be reduced.

The invention relates to the technical field of propulsion motor noise control, in particular to a propulsion motor noise control method based on short-time Fourier transform, and the method comprises the following steps: S1, collecting a vibration signal during the operation of a ship propulsion motor through a sensor, and obtaining a signal sequence; s2, converting the signal sequence into a time-frequency two-dimensional signal sequence by adopting short-time Fourier transform; and S3, obtaining an output signal by processing the time-frequency two-dimensional signal sequence. The propulsion motor noise control method based on short-time Fourier transform can continuously monitor the noise level of the motor during the operation period through combining the advantages of the sum, and quickly adjust the control strategy according to real-time feedback, thereby achieving the purpose of automatically regulating and controlling the noise, effectively reducing the operation noise of the motor, facilitating the reduction of the structural fatigue, and improving the reliability of the propulsion motor. The service life of equipment is prolonged, so that the long-term maintenance cost is reduced.

The invention relates to a wiper structure capable of reducing wind resistance lifting force, and belongs to the technical field of wipers, the wiper structure comprises a wiper and a wiper arm, the wiper arm comprises a wiper rod and a connecting piece on one side of the wiper rod, and the connecting piece is provided with a second windward side and a third windward side. According to analysis and verification, the pressure coefficient of an original windscreen wiper is designed to be 17n / m, after the wind lifting force is reduced through a new structure, the downward pressure of the windscreen wiper can be designed to be about 12N / m, the pressure of the windscreen wiper is greatly reduced, and therefore the purposes of reducing the sound generated when the windscreen wiper is used for brushing glass and reducing the noise generated when the windscreen wiper is used for brushing the glass are achieved. And meanwhile, the downward pressure of the wiper arm is small, the load of the wiper motor is reduced, so that the noise of the wiper motor is reduced, the size and the power of the motor can be reduced by reducing the load of the motor, the power consumption of the wiper can also be reduced, and the effects of energy conservation and emission reduction are achieved.

A built-in tangential mixed magnetic steel magnetism gathering type permanent magnet rotor relates to the technical field of motors, the rotor comprises a rotor iron core and a rotating shaft, the rotor iron core is provided with a plurality of permanent magnet units which are symmetrically arranged around the axis of the rotor iron core, and the permanent magnet rotor is characterized in that each permanent magnet unit comprises a middle magnetic steel, middle air permanent magnet grooves and radial magnetic steel are arranged between the adjacent permanent magnet units, the middle air permanent magnet grooves and the radial magnetic steel are arranged on the q shaft, the middle air permanent magnet grooves are arranged on the inner sides of the radial magnetic steel, and the middle magnetic steel and the adjacent radial magnetic steel on the two sides of the middle magnetic steel are arranged in a U shape. The rotor provided by the utility model can reduce motor noise and torque ripple.