321 results about "Motor noise" patented technology

The invention discloses a transformer electromagnetic vibration noise calculating method based on the finite element method. The transformer electromagnetic vibration noise calculating method comprises the steps of 1, establishing a structured grid model and an acoustics grid model according to a three-dimensional geometrical model of a transformer; 2, conducting transient electromagnetic simulation on the structured grid model to obtain transient electromagnetic force waves borne by each phase winding and an iron core; 3, conducting FFT on the transient electromagnetic force waves borne by each phase winding and the iron core to obtain the frequency domain distribution of electromagnetic force borne by each phase winding and the iron core; 4, conducting harmonic response analysis on the structured grid model to obtain the vibration displacement data of nodes on the surfaces of the windings and the iron core; 5, conducting sound field calculation on the acoustics grid model to obtain the radiation noise distribution of the transformer. According to the transformer electromagnetic vibration noise calculating method, all noise influence factors are considered, and calculation results are accurate and reliable. The transformer electromagnetic vibration noise calculating method can be used for winding short circuit vibration deformation analysis and the like and can also provide method and basis for motor noise analysis.

A low noise electronic three phase bridge controlled brushless DC motor suitable for whiteware appliance pumps and other appliance applications. Back EMF zero crossing sensing is used to determine rotor position and thus stator winding commutation times. Motor torque and speed are controlled by pulse width modulating the operation of that bridge switching device which has just been switched from an OFF state to an ON state on each new commutation. All three stator windings have current flowing in each winding commutation to improve motor current waveform and thereby reduce motor noise, but the current in one winding is always terminated before the end of the commutation period to allow the back EMF in that winding to be sensed to zero crossing.

A massage machine using a small size and high torque brushless DC motor includes a driving unit moved up and down along guide rails of a chair and a first motor for moving the driving unit up and down. A pair of treatment head bases are driven reciprocally in opposite directions to each other; and a second motor reciprocally drives the treatment head bases in opposite directions to each other. Treatment heads are respectively supported by the treatment head bases; and a third motor drives the treatment heads in a plane substantially perpendicular to a backrest. A control circuit drives the respective motors respectively independently of one another. Each motor is a brushless motor. A control circuit corrects, corresponding to a load imposed on the brushless DC motor, a waveform of a drive signal applied to a winding of the brushless DC motor so as to allow a current flowing through the winding of the brushless DC motor to have a substantially sinusoidal waveform making it possible to reduce discomfort due to motor noise, and to accurately control the motor rotation speed.

A method and system for reducing audible motor noise in a system for reconstructing motor phase current from a DC bus current comprising current pulses on a DC bus in a PWM inverter motor drive system having a PWM cycle, and for controlling the motor, which forms a command voltage vector according to a space vector modulation arrangement for controlling the motor; measures the DC bus current on the DC bus supplying power to the inverter to reconstruct said motor phase current; and determines when the command voltage vector results in an inverter switching state that prevents the measuring of the DC bus current from accurately indicating motor phase current. During said inverter switching state, a current sampling scheduler applies a minimum pulse width constraint to said current pulses in said DC bus current to improve reconstruction of said motor phase current based on said DC bus current; and reduces the application of said minimum pulse width constraint to less than once per PWM cycle imposed by the PWM inverter motor drive system, thereby allowing motor phase current reconstruction with reduced audible motor noise. The current sampling scheduler synchronously samples said measured motor phase current to reduce errors in said measured motor phase current caused by said reduction of said minimum pulse constraint; reduces a bandwidth of said motor controller during said inverter switching state; and is adjustable in response to motor speed for setting the number of said minimum pulse width constraints per PWM cycle.

The invention relates to a low-noise energy-saving test bed for the offline detection of 55KW-stage electric loading for an automobile gear-box and an operating method thereof. The test bed comprises a test bed main body, a motor box body, an electric transmission control system, a computer measuring-controlling system and an intensive oil supply hydraulic station, and is characterized in that a noise measuring device is arranged on the tested gear-box and a tray sliding table is arranged under the tested gear-box; and a gear shift device and a handle gear shift force operation measuring device are arranged on the right side of an operator who faces to the test bed. The test bed has the advantages of providing large torque up to 140Nm and meeting requirements on 30 to 100 percent of the factory detection of the loading of the gear-box with multi-specification variety types in the range of between 90 and 350Nm, reducing noise of a machine tool to be lower than 80dB through motor noise isolation and other noise reduction measurements, adjusting center distances and vertical dropping distances of input/output shafts to adapt to positioning and mounting of the gear-box with different variety specifications, adopting electric sealing power to feed back loading for energy conservation, and adopting an industrial control computer system and a measuring instrument to realize automatic control of a testing process.

Embodiments of the invention disclose a magnetic circuit method and finite element method-based motor noise optimization method and apparatus, which is used for solving the technical problems of relatively high noise measurement precision and cost of a permanent magnet synchronous motor and difficulty in adjusting parameters of the permanent magnet synchronous motor in a measurement process to achieve the purpose of optimizing motor noises in the prior art. The method comprises the steps of simplifying a magnetic field of the motor to a magnetic circuit through magnetic circuit method design, and generating a preliminary design model of the motor; analyzing parameters influencing cogging torque of the motor in the preliminary design model of the motor according to a finite element method, and selecting numerical values of parameters capable of reducing the cogging torque of the motor; performing radial electromagnetic force wave solving on the motor, working out radial force waves on stator teeth of the motor, and performing harmonic response analysis on an obtained solving result; and outputting vibration acceleration obtained by the harmonic response analysis to a stator shell of the motor, and performing sound field analysis to obtain a noise distribution condition around the motor.

In order to solve a problem that a motor generates a noise so as to deteriorate an environment in a vehicle if a field weakening control is executed to the motor of a electric power steering apparatus, in the case that a vehicle speed is high, the same field weakening control as the conventional one is applied to the motor because a noise generated due to a friction between a tire and a road surface and a wind noise of a vehicle body are large, and in the case that the vehicle speed is low, the field weakening control is weakly applied in comparison with the conventional one because the noise generated by the motor is felt relatively largely. Accordingly, the field weakening control can be executed in response to the vehicle speed in such a manner as to make the motor noise smaller.

A control circuit (10) for controlling the residual or tail current decay in a single phase or polyphase SRM winding when a phase is switched from active to inactive. A Hall-effect type sensor (30) senses rotor position of the SRM. Current flows through a winding (W) of the motor when the motor phase winding is active; and, current flow into the winding decays to zero when the phase becomes inactive. Semiconductor switches (22) direct current flow into the winding when the phase is active and then redirect residual energy in the winding between an energy recovery circuit and an energy dissipation circuit when the phase becomes inactive. A PWM signal generator (44) provides PWM operating signals to the switches to control current flow first into the winding and then between the recovery and dissipation circuits. A control module (42), or microprocessor (52) with a PWM output, is responsive to rotor position information for controlling operation of the PWM signal generator. The signal generator provides PWM signals having one set of signal characteristics when there is current flow to the winding and a different set of characteristics when there is not. This produces alternate intervals of zero voltage and forced commutation residual current decay while the phase is inactive. During the decay interval, both the PWM frequency and pulse duty cycle are variable to produce a current decay scheme which eliminates ringing and motor noise.

The invention relates to a motor noise reduction structure, in particular to a dust collector motor noise reduction structure. The structure comprises a motor cover for containing a motor. The motor cover internally comprises an impeller cavity and a sound elimination cavity in sequence from an air inlet to an air outlet. A movable impeller assembly is arranged in a movable impeller cavity. A first sound elimination part and/or a second sound elimination part are/is arranged in the sound elimination cavity, the first sound elimination part comprises an oblique grid, and the second sound elimination part comprises small dense holes formed in the air outlet and a sound elimination material arranged on the inner side of the air outlet. The air noise can be effectively reduced.

The invention relates to the field of an electric tool, and discloses a stator mounting apparatus, a stator mounting structure and a fan system. The stator mounting apparatus (40) comprises a barrel-shaped shell (41) and a connecting piece (42) mounted on the inner wall of the shell; the connecting piece comprises a first part (421) connected to the shell and a second part (42) which extends from the first part (421) towards the inner side of the shell; a stator (50) is mounted on the second part; a radial positioning part (421a) for radially limiting the mounting position of the stator is arranged on the first part; and a circumferential positioning part (43) used for circumferentially limiting the mounting position of the stator is arranged on the shell. By virtue of the stator mounting apparatus disclosed in the invention, the mounting position of the stator can be accurately positioned, thereby ensuring the mounting precision of the stator; and therefore, accurate mounting of a rotor can be matched, and higher air gap uniformity can be obtained, thereby lowering motor noise.

The invention relates to a permanent magnet synchronous motor model-free prediction control method based on an extended state observer, and the method comprises the steps: A, estimating unknown and disturbance parts of a system through employing a linear extended state observer, and not relating to motor parameters; and B, enabling the motor reference current vector and the feedback current vectorto pass through a permanent magnet synchronous motor model-free controller based on an extended state observer, obtaining a reference voltage vector by using a complex vector current regulator, and obtaining six paths of switching signals of an inverter after PWM modulation, thereby realizing control of the motor. According to the invention, the problems of large motor noise, steady-state torque,large current ripple, static current difference and poor system control performance in a traditional model prediction control scheme when motor parameters are inaccurate are solved.

A motor driving error is prevented. In concrete, disturbance in a rotation detection signal of a resolver due to motor noise is reduced. An inverter is controlled to set output torque of a rotating armature at target torque using the target torque, rotation speed and a rotation angle of the rotating armature. Three-phase/two-phase modulation takes place, wherein control of the inverter is changedfrom three-phase modulation to two-phase modulation when a modulation ratio expressed as a ratio of voltage applied to the rotating armature for voltage input to the inverter is larger than three-phase/two-phase modulation changeover boundary. Even in a three-phase modulation region where the modulation ratio is smaller than the three-phase/two-phase modulation changeover boundary, the modulationis changed over to the two-phase modulation in a specific region where torque of the rotating armature corresponding to the mentioned boundary, a torque threshold lower than the rotation speed and electric noise applied by the rotating armature exceeding the rotation speed threshold to the resolver are large. In an embodiment using step-up voltage (Vuc), the torque threshold is made to be the lower the higher the step-up voltage, to enlarge the specific region.

The invention provides a motor for a brushless DC motor, which has small torque ripple even if a trapezoidal wave current is supplied and has a small size and reduced motor noise, and a drive control device for the motor as well as an electric power steering device using the motor and the drive control device. Respective phase current command values are calculated on the basis of vector control. Pseudo-vector control for controlling respective phases separately is used as current feedback control.

A circuit and method for detecting an operating transition of a mechanical apparatus driven by a hydraulic prime mover comprising a hydraulic pump driven by an electric motor, the operating transition causing a change in the force applied by the mechanical apparatus on the prime mover. A motor current sensing circuit is connected in a motor power supply circuit to provide a motor current signal representing motor current. A bandpass filter receives the motor current signal and provides a filtered motor current signal consisting essentially of motor current signal components in the frequency range from a lower frequency boundary greater than zero Hz to an upper frequency boundary below substantially all the motor noise frequencies. A comparison circuit compares the filtered motor current signal to a first selected threshold level and outputs a signal representing the occurrence of the operating transition when the filtered motor current signal exceeds the selected threshold level. The circuit is preferably implemented with a digital controller programmed to perform these operations.

The invention provides a motor rotor and an electric motor having the electric motor. The motor rotor includes a rotor core, and a magnetic pole structure is arranged on the rotor core; the magnetic pole structure includes a multi-layer magnetic steel groove, wherein both ends of every layer of the magnetic steel groove are provided with magnetic isolating bridges; permanent magnetic structures, each of which is correspondingly arranged in every layer of the magnetic steel groove, and at least one permanent magnetic structure includes a plurality of magnetic steels, and a plurality of magnetic steels include a middle magnetic steel and even number of side magnetic steels; the center line of the middle magnetic steel is overlapped with the center line of the magnetic pole, the side magnetic steels are symmetrically arranged at both sides of the middle magnetic steel; a retained magnetic bridge is arranged between adjacent two magnetic steels, and the center line of every layer of the retained magnetic bridge is not located on the same one line. By adopting the motor rotor, the motor noise can be reduced.

The invention discloses a motor noise-reducing structure of a dust collector. The motor noise-reducing structure of the dust collector comprises a motor inner cover, wherein the motor inner cover is installed at the outer side of a dust collector motor, a first airflow cavity is formed between the motor inner cover and the dust collector motor, and the first airflow cavity is internally provided with a spiral flow guide plate; a motor outer cover, wherein the motor outer cover is installed at the outer side of the motor inner cover, a second airflow cavity is formed between the motor outer cover and the motor inner cover, the motor outer cover is a double-layer structure, the motor outer cover comprises an outer cover inner ring and an outer cover outer ring, a cavity is formed between theouter cover inner ring and the outer cover outer ring, the cavity is internally provided with a plurality of separating plates, and the separating plates are used for separating the cavity to form aplurality of noise-reducing cavities; and a shock ring, wherein the shock ring is circle-shaped, the shock ring is installed between the motor outer cover and a dust collector housing. The solution uses the noise-reducing structure, has the functions of sound insulation, shock absorption and noise reduction, and is capable of solving the technical problem that the noise of a current dust collectoris larger.