Method for eliminating vibration of PWM powered brushless direct current motor through frequency calculation

Abstract

The invention provides a method for eliminating vibration of a PWM powered brushless direct current motor through frequency calculation. For the motor preliminarily designed in a electromagnetic scheme, spatial harmonic distribution of air gap flux density is firstly calculated, then the time harmonic wave change of the air gap flux density is calculated within a commutation period and is compared with the inherent vibration frequency of a motor iron core, and if the frequencies are similar, resonance is produced, the electromagnetic design scheme of the motor is needed to be optimized, and the frequencies are re-calculated till the vibrations produced by spatial harmonic flux density and harmonic wave flux density are not resonant with the iron core. The space and time changes of flux density causing motor vibration under the operating working condition of the motor are fully considered in the method, the accuracy of motor vibration calculation in a motor product development phase is improved, accordingly the success rate of motor design is improved, a development and trial-manufacturing period of the motor is shortened, and non-renewable resources including copper, iron, aluminum and the like are effectively saved.

Description

technical field [0001] The invention relates to a method for suppressing motor vibration by calculating the motor stator core vibration frequency caused by air-gap flux density harmonics for a brushless DC motor powered by PWM (pulse width modulation mode), and belongs to the technical field of DC motors. Background technique [0002] The vibration sources of brushless DC motor vibration can be divided into three types: electromagnetic force, aerodynamic force and mechanical structure. These three vibration sources have large differences in vibration frequency, and the noise generated by vibration is easy to distinguish. The vibration generated by aerodynamic force and mechanical structure as the vibration source is mechanical vibration, which can be optimized through the design of the motor structure, such as improving the motor ventilation structure, changing the geometric dimensions of the motor structural parts, etc., and the vibration generated by the electromagnetic for...

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Problems solved by technology

[0007] 1. The calculation method of the equivalent magnetic circuit is adopted, and the parameters such as magnetic permeability are equivalent values, and the influence of the shape of the cogging on the magnetic permeability is not considered;

[0008] 2. The magnetic density value is calculated from the magnetic potential and magnetic permeability. The air gap magnetic density calculation result is an equivalent value, and the amplitude calculation of each harmonic of the magnetic density is inaccurate;

[0009] 3. Only the space harmonics of the air-gap flux density generated by the stator and rotor are considered, and the change of the air-gap flux density with time during PWM power supply is not considered

[0010] The above defects make the calculation of motor vibration frequency under PWM power supply inaccurate

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