CN104408227A - Loudspeaker distortion feature value simulation analysis method - Google Patents
Loudspeaker distortion feature value simulation analysis method Download PDFInfo
- Publication number
- CN104408227A CN104408227A CN201410586208.6A CN201410586208A CN104408227A CN 104408227 A CN104408227 A CN 104408227A CN 201410586208 A CN201410586208 A CN 201410586208A CN 104408227 A CN104408227 A CN 104408227A
- Authority
- CN
- China
- Prior art keywords
- loudspeaker
- voice coil
- distortion
- magnetic
- model
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
Abstract
The invention discloses a loudspeaker distortion feature value simulation analysis method, and belongs to the filed of loudspeaker design. According to the method, firstly, a loudspeaker geometrical model and an air region geometrical model are drawn in drawing software; then, the built geometrical models are subjected to material feature definition, physical field environment setting, grid division and boundary condition definition in finite element analysis software, and a finite element model is obtained; next, the finite element model is subjected to three-field coupling transient solving by a finite element solver , and time domain acoustic pressure signals, generated in the space specified point, of a loudspeaker are obtained; finally, a stability region of the time domain acoustic pressure signals is subjected to spectral analysis, and after the amplitude values of different frequency points are extracted, loudspeaker distortion such as harmonic distortion, intermodulation distortion or subharmonic distortion of the loudspeaker can be obtained through calculation. The loudspeaker distortion feature value simulation analysis method has the advantages that the distortion features of the loudspeaker can be obtained in the initial design state , i.e., before samples are not produced or manufactured, so the design and the manufacturing of the loudspeaker are fast and convenient.
Description
Technical field
What the present invention relates to is a kind of Numerical Simulation Analysis method of loudspeaker distortions characteristic, belongs to loudspeaker design of Simulation field.
Background technology
Loudspeaker distortions is divided into linear distortion and nonlinear distortion, and the latter is caused by the amplitude non-linearity of loudspeaker, and the ability generation major effect of its sound of verily resetting to loudspeaker, comprises harmonic distortion, intermodulation distortion and subharmonic distortion etc.
Harmonic distortion refers to when loudspeaker inputs the sinusoidal signal of a certain frequency, in the acoustical signal that loudspeaker exports, except the signal of former input, occurs the harmonic component such as secondary, third harmonic simultaneously.Usual harmonic distortion of loudspeaker appears at low-frequency range, particularly at vibrational system resonant frequency
f 0comparatively large time neighbouring, its main source has three: vibrational system is non-linear, and it causes loudspeaker to occur third harmonic distortion when large-amplitude vibration; In magnetic gap, Magnetic Induction Density Distribution is uneven, and it causes loudspeaker to occur second harmonic distortion when large-amplitude vibration; Aeroelastic non-linear, the air closed under dust cap, the air closed between centring disk and frame can cause second harmonic distortion.
Intermodulation distortion refers to when two frequencies are respectively
f 1with
f 2sinusoidal signal when being simultaneously added to loudspeaker, non-linear due to loudspeaker, in its output acoustic pressure, there will be
f 1with
f 2with difference frequency (
f 2±
f 1,
f 2± 2
f 1) signal.Except loudspeaker amplitude non-linearity, because the reasons such as the directive property of Doppler effect, loudspeaker, the interference of audio amplifier medium-high frequency woofer all can produce intermodulation distortion.
When subharmonic distortion refers to the sinusoidal signal when strengthening to loudspeaker, can produce in intermediate frequency, low-frequency range the blurred signal that frequency is the signal frequency such as 1/2 or 1/3, be referred to as " semitone " in factory, intermittently occur, it causes by vibrating diaphragm is non-linear.
Distortion is very important performance index of loudspeaker, it is directly connected to the sound reproduction quality of loudspeaker, therefore the distorted characteristic of each loudspeaker manufacturing enterprise to loudspeaker is paid much attention to, but the method analyzing loudspeaker distortions characteristic at present in enterprise is still traditional empirical method, be generally the iterative cycles process that sample has a fling at, tests, improves sample again, tests, this mode by the time must design the later stage and could find speakerphone problem, and the construction cycle is long, cost is high.
Along with the development of computer technology, use Numerical Simulation Analysis method to carry out Computer Aided Design and become more and more extensive, Numerical Simulation Analysis method is applied to loudspeaker design and can has a fling at sample the performance that early stage estimates loudspeaker, thus accelerate the design schedule of loudspeaker, reduce cost of development.At present at home also not about the precedent published using Numerical Simulation Analysis method to analyze loudspeaker distortions characteristic.
Summary of the invention
The object of the invention is a kind of Numerical Simulation Analysis method obtaining loudspeaker distortions characteristic;
The present invention is to solve when analyzing loudspeaker distortions characteristic, what empirical method existed must wait until that the design later stage could find speakerphone problem and the problem that the construction cycle is long, cost is high.The present invention is based on the THM coupling analysis of magnetic circuit of loudspeaker, vibrational system and sound field to carry out distorted characteristic analysis, thus analysis result compared to single game or two independent analysis more comprehensive and accurate;
The Numerical Simulation Analysis method of a kind of loudspeaker distortions characteristic of the present invention, concrete steps are:
(1) the geometric model figure of loudspeaker and air-shed is set up
Use mapping software or the direct three-dimensional 3D geometric model figure drawing loudspeaker and air-shed in finite element analysis software, wherein the geometric model of loudspeaker should comprise the magnetic circuit of loudspeaker and vibrational system, if model is circular, then set up the 2D rotational symmetry simplified model of loudspeaker;
(2) set up the finite element model of loudspeaker and air-shed geometric model, concrete steps are as follows:
A. definition material parameter, the material parameter of each parts of Definition Model, comprise the magnetization curve value (i.e. BH value and HB value) of train wheel bridge and magnetic conductor bowl, the Rayleigh damping of the Young modulus of the characteristic of air and each parts of vibrational system, Poisson ratio, density and structure;
B., physical field environment is set, loudspeaker is the lower coupling that can relate to electromagnetic field, vibration and sound field multiple physical field in working order, therefore need to arrange each physical field environment respectively: 1) magnetic field constitutive relation, arranges the magnetic characteristic of the residual magnetic flux density of magnet steel in the magnetic circuit of loudspeaker, train wheel bridge and magnetic conductor bowl; 2) multiturn coil, because voice coil loudspeaker voice coil is formed by enameled wire coiling, and the voice coil loudspeaker voice coil in model is a rectangular area, therefore will define the number of turn of voice coil loudspeaker voice coil, sectional area and terminal voltage; 3) air layer adds spherical wave radiation border outside;
C. grid division, carries out stress and strain model to the geometric model of loudspeaker, obtains the analytic unit that finite element analysis is used, if 2D model, selects face unit, if 3D model, then and selective body unit;
D. boundary condition is defined, 1) fixed boundary condition, because loudspeaker ring and centring disk are fixed in frame, need at its Edge definition fixed boundary condition; 2) imposed load, applies driving force at the voice coil loudspeaker voice coil position of model.When analyzing different distorted characteristics, the loading applied is also different, such as when analyzing harmonic distortion of loudspeaker and subharmonic distortion, need the driving force of an applying single frequency sinusoidal signal, when analyzing the intermodulation distortion of loudspeaker, then need the driving force that applying one is superposed by the sinusoidal signal of two frequencies;
(3) with finite element solving device, finite element model is solved
Solve and be divided into two steps: the Maxwell equation first solving magnetic circuit part static magnetic field, obtain the stable state magnetic flux distribution of loudspeaker; Then magnetic circuit is carried out and acoustic power flow transient state solves, comprise the Maxwell equation solved under time-varying field, many-degrees of freedom system forced vibration equation harmony shakes coupled wave equation, complete the THM coupling transient analysis of magnetic circuit, vibrational system and sound field, and obtain the time domain sound pressure signal that loudspeaker produces at specified point place;
A. magnetic circuit steady-state analysis is carried out to finite element model
By solving the Maxwell equation of magnetic circuit of loudspeaker part static magnetic field, obtain the stable state magnetic flux distribution at magnetic gap place, loudspeaker voice coil place;
B. THM coupling transient analysis is carried out to finite element model
A. the transient analysis that is coupled of magnetic circuit and vibrational system
Magnetic circuit of loudspeaker shows as with being coupled of vibrational system: on the one hand, energized coils is subject to the effect of Lorentz force and produces motion in magnetic field, thus promote whole vibrational system and vibrate, the voice coil loudspeaker voice coil simultaneously moved can produce induction electromotive force due to cutting magnetic induction line, and then affects voice coil drive force size; On the other hand, the induction field produced by exchange current on voice coil loudspeaker voice coil also can affect the Magnetic Induction Density Distribution of magnetic circuit system;
Maxwell equation under time-varying field can be expressed as:
In above formula, σ is conductivity,
for the current density in voice coil loudspeaker voice coil, it comprises marking current density and induced current density.Can be solved by above formula and obtain
a , thus can calculated magnetic induction intensity
:
In addition, due in the oscillating region of voice coil loudspeaker voice coil, the distribution of magnetic induction density is uneven, and therefore the non-linear meeting of magnetic circuit causes the non-linear of voice coil drive force;
The power of hot-wire coil suffered by magnetic field is:
In above formula,
nfor the coil turn of voice coil loudspeaker voice coil,
rfor voice coil loudspeaker voice coil radius,
for the electric current in voice coil loudspeaker voice coil, comprise marking current and induction current;
B. coupled vibro-acoustic transient analysis
Speaker vibration system shows as with being coupled of sound field: on the one hand, and vibrational system is to radiative acoustic wave in air; On the other hand, sound wave also can produce reacting force to vibrational system, and has an impact to vibrational state;
The vibration mode of loudspeaker under humorous load effect can be characterized by many-degrees of freedom system forced vibration, its vibration displacement
u(t) } meet following many-degrees of freedom system forced vibration equation:
In above formula, [
m] for comprising the vibrational system mass matrix of airequivalent quality, [
c] be resistance coefficient matrix, [
k] be stiffness matrix,
ffor driving force amplitude,
for the angular frequency of humorous load,
for sound wave is to the reacting force of vibrational system;
Solve above-mentioned fundamental equation:
{
u(
t)}= {
u 1(
t)}+ {
u 2(
t)}
This solution is made up of two parts,
u 1(
t) be the general solution of corresponding homogeneous equation, it is relevant with starting condition, is the transient silution that system does free vibration attenuation; {
u 2(
t) be the particular solution of corresponding nonhomogeneous equation, be the steady state solution that system does forced vibration; When carrying out loudspeaker distortions specificity analysis, need study equation steady state solution
u 2(
t);
In the position that air is coupled with vibrational system (mainly cone region), the vibration acceleration in structure normal direction is identical with the vibration acceleration of air normal direction, like this at coupling boundary place setting acceleration
, the atmospheric pressure that border produces is calculated by coupled vibro-acoustic equation
p:
Wherein,
ρfor density of material,
nfor the normal direction vector of unit length on coupling boundary.Can realize vibrational system vibration by above formula drives air vibration to form sound wave, is equivalent to the acceleration sound source in sound field.
Simultaneously on the border of vibrational system and sound field, air pressure is forced acoustic pressure to be carried on border and is produced stress to vibrational system:
Wherein,
for structural stress.Sound wave can be realized by above formula and reacting force is produced to vibrational system, and vibrational state is had an impact;
(4) calculated distortion
The distorted characteristic of loudspeaker can be calculated by the loudspeaker time domain sound pressure signal obtained by THM coupling transient analysis, comprise harmonic distortion, intermodulation distortion and subharmonic distortion etc., as example, provide the computing method of first two distortion herein;
A. harmonic distortion is calculated.FFT spectrum analysis is carried out to the stabilization sub stage of time domain sound pressure signal, and extract higher hamonic wave, then calculate loudspeaker by following formula
nsubharmonic distortion (
n=2 or 3) and total harmonic distortion:
Second harmonic distortion:
Third harmonic distortion:
Total harmonic distortion:
In above formula,
represent the total acoustic pressure comprising fundamental frequency;
B. intermodulation distortion is calculated.If
f 1with
f 2two frequencies of input signal, wherein
f 1be less than
f 2, and between two frequencies, there is no the relation of integral multiple.FFT spectrum analysis is carried out to the stabilization sub stage of time domain sound pressure signal, and extracts frequency
f 2± (
n-1)
f 1corresponding intermodulation component, then calculates the of loudspeaker by following formula
nsecondary intermodulation distortion, as:
Secondary intermodulation distortion:
Three intermodulation distortion:
The general high order intermodulation distortion not considering more than four times.
Advantage of the present invention is: the inventive method considers the relation that intercouples of the magnetic circuit of loudspeaker, vibrational system and sound field comprehensively, solved by THM coupling transient analysis and calculate with spectrum analysis, obtain the distortion of loudspeaker, therefore the present invention can fast, low cost and estimate the distorted characteristic of loudspeaker exactly, thus shorten the R&D cycle of loudspeaker, improve the performance of loudspeaker.
Accompanying drawing explanation
Fig. 1 is the invention process method flow diagram.
Fig. 2 is THM coupling transient analysis schematic diagram.
Fig. 3 is the 3D geometric model of a 6.5 inches of auto loud hailers.
Fig. 4 is 2D rotational symmetry geometric model and the air-shed model of a 6.5 inches of auto loud hailers.
Fig. 5 is BH (or HB) value of train wheel bridge and magnetic conductor bowl.
Fig. 6 is the material parameter of each parts of vibrational system.
Fig. 7 is the Rayleigh damping coefficient of vibrational system.
Fig. 8 is multiturn coil parameter.
Fig. 9 is the finite element model of this loudspeaker.
Figure 10 is this loudspeaker time domain pressure response curve.
Figure 11 is the spectrum analysis figure of this loudspeaker time domain pressure response.
Figure 12 is front 5 order harmonics distortion components.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described.
The present invention, for a 6.5 inches of auto loud hailers, uses its harmonic distortion of simulation analysis and the intermodulation distortion respectively of COMSOL software, and directly gives the simulation analysis result of harmonic distortion.Fig. 1 is the invention process method flow diagram, mainly contains following steps:
Step 1: because this loudspeaker is axially symmetric structure, as shown in Figure 3, therefore for the ease of calculating, first 2D rotational symmetry analysis environments is selected in COMSOL software, then magnetic field analysis module, acoustic power flow analysis module and mobile grid module is selected, because carry out the transient analysis of THM coupling, select the analytical model with time correlation so last;
Step 2: the 2D rotational symmetry geometric model using COMSOL software creation loudspeaker and air-shed, as shown in Figure 4.As seen from the figure, this loudspeaker is made up of two parts: (1) magnetic circuit system, comprises magnetic conductor bowl, magnet steel and train wheel bridge, mainly produce magnetic field, produces driving force to energized coils; (2) vibrational system, comprises dust cap, speech coil framework, voice coil loudspeaker voice coil, centring disk and ring.In order to avoid the interference of loudspeaker front in anti-phase with rear sound wave, set up infinitely great baffle model at the edge of ring, air-shed before and after loudspeaker is separated.Create the point that coordinate is (0,150mm), as the reference point of THM coupling transient analysis result;
Step 3: use COMSOL to set up the finite element model (see figure 9) of loudspeaker.Concrete steps are as follows:
1) average function of voice coil loudspeaker voice coil is set, and called after coil_av, this is the arithmetic mean in order to define inverse electromotive force in voice coil loudspeaker voice coil territory.
2) definition material characteristic.For the loudspeaker of this example, the material of train wheel bridge and magnetic conductor bowl is soft iron, needs manually itself BH and HB value of input, as shown in Figure 5; Magnetic steel material is equivalent to air; The material of voice coil loudspeaker voice coil is copper, defines the Young modulus of each parts of vibrational system, Poisson ratio and density, as shown in Figure 6; The Rayleigh damping coefficient of vibrational system is set, as shown in Figure 7;
Rayleigh damping parameter
with
computing formula be respectively:
With
Wherein
f 1,
f 2any two resonant frequencies of loudspeaker,
,
be respectively with
f 1,
f 2corresponding damping factor, can more than half power method, obtains from loudspeaker amplitude-versus-frequency curve;
3) physical field environment is set.The z durection component arranging the residual magnetic flux density of magnet steel is 0.37T; The constitutive relation of train wheel bridge and magnetic conductor bowl is set to HB curve; Definition multiturn coil, as shown in Figure 8, wherein, for different distorted characteristic analyses, the driving voltage of voice coil loudspeaker voice coil is also different, but be all be divided into two, for Research of Analysis System for Harmonic Distortion: driving voltage expression formula Section 1 is 8.484 [V] * sin (2*pi*50 [Hz] * t), the single-frequency voltage excitation signals that expression amplitude is 8.484V, frequency is 50Hz, Section 2 is coil_av (astd.u_tZ*mf.Br*2*pi*r*N), the inverse electromotive force produced when representing that voice coil loudspeaker voice coil moves in magnetic field.Intermodulation distortion is analyzed: driving voltage expression formula Section 1 is 8.484 [V] * (sin (2*pi*45 [Hz] * t)+sin (2*pi*400 [Hz] * t)), the superposition of the single-frequency voltage excitation signals that the single-frequency voltage excitation signals that expression amplitude is 8.484V, frequency is 45Hz and amplitude are 8.484V, frequency is 400Hz, the inverse electromotive force produced when Section 2 represents that voice coil loudspeaker voice coil moves in magnetic field; Air-shed outermost one deck adds spherical wave radiation border;
4) boundary condition is defined.Because the edge of loudspeaker ring and centring disk is fixed in frame, at the Edge definition fixed boundary condition of loudspeaker ring and centring disk.Voice coil loudspeaker voice coil applies the distributed force that size is-mf.Br*mf.Jphi, and wherein-mf.Br is magnetic density, and mf.Jphi is circumferential current density;
5) stress and strain model.The trellis-type arranging outer space gas-bearing formation is map unit, and the trellis-type of interior air-shed, vibrational system and magnetic circuit system is free triangular unit, and unit size is all set to Extra fine.Add boundary layer to train wheel bridge and magnetic conductor bowl, the number of plies is 3, and ground floor thickness is set to 0.2mm.In mobile grid module, arrange air section is Free Transform region, the border be connected with magnetic circuit system in fixing Free Transform region, to arrange r direction, the border speed be connected with vibrational system in Free Transform region be astd.u_tR, z direction speed is astd.u_tZ;
Step 4: arranging and calculating T.T. and time step is range (0,0.25 [ms], 550 [ms]), and chooses geometrical non-linearity option, and arranging tolerance is 0.001.Click Study to start to carry out THM coupling transient analysis, solve and be divided into two steps: the stable state of first carrying out magnetic circuit part solves, loudspeaker can be obtained, the particularly stable state magnetic flux distribution of voice coil loudspeaker voice coil place magnetic gap part, thus provide necessary parameter for next step magnetic circuit and the transient analysis that is coupled of vibrational system; Then carry out magnetic circuit and acoustic power flow transient state solves, complete the THM coupling transient analysis of magnetic circuit, vibrational system and sound field, and obtain the time domain sound pressure signal that loudspeaker produces at specified point (0,150mm) place;
A. the transient analysis that is coupled of magnetic circuit and vibrational system
Magnetic circuit of loudspeaker shows as with being coupled of vibrational system: on the one hand, energized coils is subject to the effect of Lorentz force and produces motion in magnetic field, thus promote whole vibrational system and vibrate, the voice coil loudspeaker voice coil simultaneously moved can produce induction electromotive force due to cutting magnetic induction line, and then affects voice coil drive force size; On the other hand, the induction field produced by exchange current on voice coil loudspeaker voice coil also can affect the Magnetic Induction Density Distribution of magnetic circuit system;
Maxwell equation under time-varying field can be expressed as:
In above formula, σ is conductivity,
for the current density in voice coil loudspeaker voice coil, it comprises marking current density and induced current density.Can be solved by above formula and obtain
a , thus can calculated magnetic induction intensity
:
In addition, due in the oscillating region of voice coil loudspeaker voice coil, the distribution of magnetic induction density is uneven, and therefore the non-linear meeting of magnetic circuit causes the non-linear of voice coil drive force;
The power of hot-wire coil suffered by magnetic field is:
In above formula,
nfor the coil turn of voice coil loudspeaker voice coil,
rfor voice coil loudspeaker voice coil radius,
for the electric current in voice coil loudspeaker voice coil, comprise marking current and induction current;
B. coupled vibro-acoustic transient analysis
Speaker vibration system shows as with being coupled of sound field: on the one hand, and vibrational system is to radiative acoustic wave in air; On the other hand, sound wave also can produce reacting force to vibrational system, and has an impact to vibrational state;
The vibration mode of loudspeaker under humorous load effect can be characterized by many-degrees of freedom system forced vibration, its vibration displacement
u(
t) meet following fundamental equation:
In above formula, [
m] for comprising the vibrational system mass matrix of airequivalent quality, [
c] be resistance coefficient matrix, [
k] be stiffness matrix,
ffor driving force amplitude,
for the angular frequency of humorous load,
for sound wave is to the reacting force of vibrational system;
Solve above-mentioned fundamental equation, can obtain:
{
u(
t)}= {
u 1(
t)}+ {
u 2(
t)}
This solution is made up of two parts,
u 1(
t) be the general solution of corresponding homogeneous equation, it is relevant with starting condition, is the transient silution that system does free vibration attenuation; {
u 2(
t) be the particular solution of corresponding nonhomogeneous equation, be the steady state solution that system does forced vibration.When carrying out loudspeaker distortions specificity analysis, need study equation steady state solution
u 2(
t);
In the position that air is coupled with vibrational system (mainly cone region), the vibration acceleration in structure normal direction is identical with the vibration acceleration of air normal direction, like this at coupling boundary place setting acceleration
, calculate the acoustic pressure that border produces:
Wherein,
ρfor density of material,
nfor the normal direction vector of unit length on coupling boundary.Can realize vibrational system vibration by above formula drives air vibration to form sound wave, is equivalent to the acceleration sound source in sound field.
Simultaneously setting air pressure on the border of vibrational system and sound field
p, acoustic pressure is carried on border stress is produced to vibrational system:
Wherein,
for structural stress.Sound wave can be realized by above formula and reacting force is produced to vibrational system, and vibrational state is had an impact;
Calculating terminates the time domain pressure response at rear extraction loudspeaker specified point (0,150mm) place in air-shed, sees Figure 10;
Step 5: calculated distortion.
A. harmonic distortion is calculated.FFT spectrum analysis is carried out to the stabilization sub stage of time domain sound pressure signal, and extract higher hamonic wave, as shown in figure 12, then calculate loudspeaker by following formula
nsubharmonic distortion (
n=2 or 3) and total harmonic distortion (get front 5 order harmonic component as approximate):
Second harmonic distortion:
Third harmonic distortion:
Total harmonic distortion:
In above formula,
, approximate representation comprises total acoustic pressure of fundamental frequency;
B. intermodulation distortion is calculated.FFT spectrum analysis is carried out to the stabilization sub stage of time domain sound pressure signal, and extracts the intermodulation component of frequency 400Hz, (400Hz ± 45Hz) and (400Hz ± 90Hz) correspondence, then calculated second and third intermodulation distortion of loudspeaker by following formula:
Secondary intermodulation distortion:
Three intermodulation distortion:
Last it is noted that above case study on implementation is only in order to illustrate implementation procedure of the present invention, and and unrestricted technical scheme described in the invention.Therefore, although this instructions with reference to above-mentioned each step to invention has been detailed description, but, those of ordinary skill in the art is to be understood that, still can modify to the present invention or equivalent replacement, and all do not depart from technical scheme and the improvement thereof of the spirit and scope of the present invention, all should be encompassed in right of the present invention.
Claims (4)
1. a Numerical Simulation Analysis method for loudspeaker distortions characteristic, is characterized in that the method at least comprises the following steps:
(1) the geometric model figure of loudspeaker and air-shed is set up
Use mapping software or the direct three-dimensional 3D geometric model figure drawing loudspeaker and air-shed in finite element analysis software, wherein the geometric model of loudspeaker should comprise the magnetic circuit of loudspeaker and vibrational system, if model is circular, then set up the 2D rotational symmetry simplified model of loudspeaker;
(2) set up the finite element model of loudspeaker and air-shed geometric model, concrete steps are as follows:
A. definition material parameter, the material parameter of each parts of Definition Model, comprises the magnetization curve value (i.e. BH value and HB value) of train wheel bridge and magnetic conductor bowl, the Rayleigh damping of the Young modulus of the characteristic of air and each parts of vibrational system, Poisson ratio, density and structure;
B. arrange physical field environment, loudspeaker is the lower coupling that can relate to electromagnetic field, vibration and sound field multiple physical field in working order
Close, therefore need to arrange each physical field environment respectively; Physical field environment comprises: 1) magnetic field constitutive relation, arranges the magnetic characteristic of the residual magnetic flux density of magnet steel in the magnetic circuit of loudspeaker, train wheel bridge and magnetic conductor bowl; 2) multiturn coil, because voice coil loudspeaker voice coil is formed by enameled wire coiling, and the voice coil loudspeaker voice coil in model is a rectangular area, therefore will define the number of turn of voice coil loudspeaker voice coil, sectional area and terminal voltage; 3) air layer adds spherical wave radiation border outside;
C. grid division, carries out stress and strain model to the geometric model of loudspeaker, obtains the analytic unit that finite element analysis is used, if 2D model, selects face unit, if 3D model, then and selective body unit;
D. boundary condition is defined, 1) fixed boundary condition, because loudspeaker ring and centring disk are fixed in frame, need at its Edge definition fixed boundary condition; 2) imposed load, applies driving force at the voice coil loudspeaker voice coil position of model; When analyzing different distorted characteristics, the loading applied is also different, such as when analyzing harmonic distortion of loudspeaker and subharmonic distortion, need the driving force of an applying single frequency sinusoidal signal, when analyzing the intermodulation distortion of loudspeaker, then need the driving force that applying one is superposed by the sinusoidal signal of two frequencies;
(3) with finite element solving device, finite element model is solved
Solve and be divided into two steps: the Maxwell equation first solving magnetic circuit part static magnetic field, obtain the stable state magnetic flux distribution of loudspeaker; Then magnetic circuit is carried out and acoustic power flow transient state solves, comprise the Maxwell equation solved under time-varying field, many-degrees of freedom system forced vibration equation harmony shakes coupled wave equation, complete the THM coupling transient analysis of magnetic circuit, vibrational system and sound field thus, and obtain the time domain sound pressure signal that loudspeaker produces at specified point place;
A. magnetic circuit steady-state analysis is carried out to finite element model
By solving the Maxwell equation of magnetic circuit of loudspeaker part static magnetic field, obtain the stable state magnetic flux distribution at magnetic gap place, loudspeaker voice coil place;
B. THM coupling transient analysis is carried out to finite element model
A. the transient analysis that is coupled of magnetic circuit and vibrational system
Magnetic circuit of loudspeaker shows as with being coupled of vibrational system: on the one hand, energized coils is subject to the effect of Lorentz force and produces motion in magnetic field, thus promote whole vibrational system and vibrate, the voice coil loudspeaker voice coil simultaneously moved can produce induction electromotive force due to cutting magnetic induction line, and then affects voice coil drive force size; On the other hand, the induction field produced by exchange current on voice coil loudspeaker voice coil also can affect the Magnetic Induction Density Distribution of magnetic circuit system;
Maxwell equation under time-varying field can be expressed as:
In above formula, σ is conductivity,
for the current density in voice coil loudspeaker voice coil, it comprises marking current density and induced current density;
Can be solved by above formula and obtain
a , thus can calculated magnetic induction intensity
b :
In addition, due in the oscillating region of voice coil loudspeaker voice coil, the distribution of magnetic induction density is uneven, and therefore the non-linear meeting of magnetic circuit causes the non-linear of voice coil drive force;
The power of hot-wire coil suffered by magnetic field is:
In above formula,
nfor the coil turn of voice coil loudspeaker voice coil,
rfor voice coil loudspeaker voice coil radius,
for the electric current in voice coil loudspeaker voice coil, comprise marking current and induction current;
B. coupled vibro-acoustic transient analysis
Speaker vibration system shows as with being coupled of sound field: on the one hand, and vibrational system is to radiative acoustic wave in air; On the other hand, sound wave also can produce reacting force to vibrational system, and has an impact to vibrational state;
The vibration mode of loudspeaker under humorous load effect can be characterized by many-degrees of freedom system forced vibration, its vibration displacement
u(t) } meet following many-degrees of freedom system forced vibration equation:
In above formula, [
m] for comprising the vibrational system mass matrix of airequivalent quality, [
c] be resistance coefficient matrix, [
k] be stiffness matrix,
ffor driving force amplitude,
for the angular frequency of humorous load,
for sound wave is to the reacting force of vibrational system;
Solve above-mentioned fundamental equation:
{
u(
t)}= {
u 1(
t)}+ {
u 2(
t)}
This solution is made up of two parts,
u 1(
t) be the general solution of corresponding homogeneous equation, it is relevant with starting condition, is the transient silution that system does free vibration attenuation; {
u 2(
t) be the particular solution of corresponding nonhomogeneous equation, be the steady state solution that system does forced vibration; When carrying out loudspeaker distortions specificity analysis, need study equation steady state solution
u 2(
t);
In the position that air is coupled with vibrational system (mainly cone region), the vibration acceleration in structure normal direction is identical with the vibration acceleration of air normal direction, like this at coupling boundary place setting acceleration
, the atmospheric pressure that border produces is calculated by coupled vibro-acoustic equation
p:
Wherein,
ρfor density of material,
nfor the normal direction vector of unit length on coupling boundary;
Can realize vibrational system vibration by above formula drives air vibration to form sound wave, is equivalent to the acceleration sound source in sound field;
Simultaneously on the border of vibrational system and sound field, air pressure is forced acoustic pressure to be carried on border and is produced stress to vibrational system:
Wherein,
for structural stress;
Sound wave can be realized by above formula and reacting force is produced to vibrational system, and vibrational state is had an impact;
(4) calculated distortion
The distorted characteristic of loudspeaker can be calculated by the loudspeaker time domain sound pressure signal obtained by THM coupling transient analysis, comprise harmonic distortion, intermodulation distortion and subharmonic distortion etc., as example, provide the computing method of first two distortion herein;
A. harmonic distortion is calculated;
FFT spectrum analysis is carried out to the stabilization sub stage of time domain sound pressure signal, and extract higher hamonic wave, then calculate loudspeaker by following formula
nsubharmonic distortion (
n=2 or 3) and total harmonic distortion:
Second harmonic distortion:
Third harmonic distortion:
Total harmonic distortion:
In above formula,
represent the total acoustic pressure comprising fundamental frequency;
B. intermodulation distortion is calculated;
If
f 1with
f 2two frequencies of input signal, wherein
f 1be less than
f 2, and between two frequencies, there is no the relation of integral multiple;
FFT spectrum analysis is carried out to the stabilization sub stage of time domain sound pressure signal, and extracts frequency
f 2± (
n-1)
f 1corresponding intermodulation component, then calculates the of loudspeaker by following formula
nsecondary intermodulation distortion, as:
Secondary intermodulation distortion:
Three intermodulation distortion:
The general high order intermodulation distortion not considering more than four times.
2. the Numerical Simulation Analysis method of loudspeaker distortions characteristic as claimed in claim 1, is characterized in that the loudspeaker selected comprises various moving oil electric loudspeaker.
3. the Numerical Simulation Analysis method of loudspeaker distortions characteristic as claimed in claim 1, is characterized in that loudspeaker distortions comprises harmonic distortion, intermodulation distortion and subharmonic distortion.
4. the Numerical Simulation Analysis method of loudspeaker distortions characteristic as claimed in claim 1, is characterized in that mapping software comprises Solidworks, Pro/E; Finite element analysis software comprises COMSOL and ANSYS.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410586208.6A CN104408227A (en) | 2014-10-28 | 2014-10-28 | Loudspeaker distortion feature value simulation analysis method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410586208.6A CN104408227A (en) | 2014-10-28 | 2014-10-28 | Loudspeaker distortion feature value simulation analysis method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN104408227A true CN104408227A (en) | 2015-03-11 |
Family
ID=52645858
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410586208.6A Pending CN104408227A (en) | 2014-10-28 | 2014-10-28 | Loudspeaker distortion feature value simulation analysis method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104408227A (en) |
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105138746A (en) * | 2015-08-08 | 2015-12-09 | 浙江中科电声研发中心 | Method for inversely deducing Young modulus of loudspeaker vibrating member by means of stiffness coefficient of loudspeaker vibrating member |
| CN105246018A (en) * | 2015-10-29 | 2016-01-13 | 浙江中科电声研发中心 | Approximate calculation method for harmonic distortion of axisymmetric loudspeaker on finite baffle |
| CN105916092A (en) * | 2016-04-06 | 2016-08-31 | 北京瑞森新谱科技有限公司 | Efficient audio frequency intermodulation distortion measurement method |
| CN106068008A (en) * | 2016-08-15 | 2016-11-02 | 歌尔科技有限公司 | Audio-frequence player device distortion measurement method |
| CN106529100A (en) * | 2016-12-23 | 2017-03-22 | 大工（青岛）新能源材料技术研究院有限公司 | Solenoid superconducting magnet coil magnetic field simulation method based on finite element analysis |
| CN106951628A (en) * | 2017-03-16 | 2017-07-14 | 吉林航盛电子有限公司 | Loudspeaker frequency tracing analysis method and device based on COMSOL softwares |
| CN109145514A (en) * | 2018-09-30 | 2019-01-04 | 浙江中科电声研发中心 | A kind of Numerical Simulation Analysis method of loudspeaker distortions |
| CN110442907A (en) * | 2019-07-02 | 2019-11-12 | 浙江中科电声研发中心 | The Numerical Simulation Analysis method of piezoelectric type MEMS loudspeaker fundamental characteristics |
| WO2020030001A1 (en) * | 2018-08-08 | 2020-02-13 | 苏州上声电子股份有限公司 | Method for designing loudspeaker mesh cover based on finite element method |
| CN111770233A (en) * | 2020-06-23 | 2020-10-13 | Oppo（重庆）智能科技有限公司 | Frequency compensation method and terminal equipment |
| CN112487679A (en) * | 2020-11-20 | 2021-03-12 | 四川湖山电器股份有限公司 | Method, system, terminal and medium for simulating acoustic characteristics of sound box by numerical values |
| CN113286233A (en) * | 2021-05-20 | 2021-08-20 | 维沃移动通信有限公司 | Loudspeaker simulation method, loudspeaker simulation device, loudspeaker and electronic equipment |
| CN113297726A (en) * | 2021-04-29 | 2021-08-24 | 益阳市信维声学科技有限公司 | Method for generating magnetic induction intensity curve of loudspeaker and terminal |
| WO2022127081A1 (en) * | 2020-12-14 | 2022-06-23 | 苏州上声电子股份有限公司 | Coaxial loudspeaker with horn and shape optimization method therefor |
| CN116095579A (en) * | 2023-04-07 | 2023-05-09 | 张家港市玉同电子科技有限公司 | Harmonic wave processing method and system of ceramic loudspeaker |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080294397A1 (en) * | 2007-05-17 | 2008-11-27 | Akira Ohnishi | Analytical method, recording medium, and analyzing apparatus |
| US20090102470A1 (en) * | 2007-10-16 | 2009-04-23 | Sharp Kabushiki Kaisha | Simulation method implemented by coupling electromagnetic field analysis method and circuit analysis method together, simulation apparatus, and computer-readable medium storing simulation program |
| CN102004823A (en) * | 2010-11-11 | 2011-04-06 | 浙江中科电声研发中心 | Numerical value simulation method of vibration and acoustic characteristics of speaker |
| CN102595286A (en) * | 2011-01-10 | 2012-07-18 | 陈国富 | Pure high pitch, clean bass and full-frequency coaxial loudspeakers |
-
2014
- 2014-10-28 CN CN201410586208.6A patent/CN104408227A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080294397A1 (en) * | 2007-05-17 | 2008-11-27 | Akira Ohnishi | Analytical method, recording medium, and analyzing apparatus |
| US20090102470A1 (en) * | 2007-10-16 | 2009-04-23 | Sharp Kabushiki Kaisha | Simulation method implemented by coupling electromagnetic field analysis method and circuit analysis method together, simulation apparatus, and computer-readable medium storing simulation program |
| CN102004823A (en) * | 2010-11-11 | 2011-04-06 | 浙江中科电声研发中心 | Numerical value simulation method of vibration and acoustic characteristics of speaker |
| CN102595286A (en) * | 2011-01-10 | 2012-07-18 | 陈国富 | Pure high pitch, clean bass and full-frequency coaxial loudspeakers |
Non-Patent Citations (2)
| Title |
|---|
| 张德银: "参量扬声器DSB法的互调失真研究", 《声学技术》 * |
| 王雷等: "降低扬声器调制失真的方法研究", 《扬声器与传声器》 * |
Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105138746A (en) * | 2015-08-08 | 2015-12-09 | 浙江中科电声研发中心 | Method for inversely deducing Young modulus of loudspeaker vibrating member by means of stiffness coefficient of loudspeaker vibrating member |
| CN105138746B (en) * | 2015-08-08 | 2018-04-17 | 浙江中科电声研发中心 | Pass through the anti-method for pushing away its Young's modulus of the stiffness factor of loudspeaker vibration component |
| CN105246018B (en) * | 2015-10-29 | 2019-02-26 | 浙江中科电声研发中心 | The approximate calculation method of limited big baffle axial symmetry harmonic distortion of loudspeaker |
| CN105246018A (en) * | 2015-10-29 | 2016-01-13 | 浙江中科电声研发中心 | Approximate calculation method for harmonic distortion of axisymmetric loudspeaker on finite baffle |
| CN105916092A (en) * | 2016-04-06 | 2016-08-31 | 北京瑞森新谱科技有限公司 | Efficient audio frequency intermodulation distortion measurement method |
| CN106068008A (en) * | 2016-08-15 | 2016-11-02 | 歌尔科技有限公司 | Audio-frequence player device distortion measurement method |
| CN106068008B (en) * | 2016-08-15 | 2019-07-19 | 歌尔科技有限公司 | Audio-frequence player device distortion measurement method |
| CN106529100A (en) * | 2016-12-23 | 2017-03-22 | 大工（青岛）新能源材料技术研究院有限公司 | Solenoid superconducting magnet coil magnetic field simulation method based on finite element analysis |
| CN106951628A (en) * | 2017-03-16 | 2017-07-14 | 吉林航盛电子有限公司 | Loudspeaker frequency tracing analysis method and device based on COMSOL softwares |
| WO2020030001A1 (en) * | 2018-08-08 | 2020-02-13 | 苏州上声电子股份有限公司 | Method for designing loudspeaker mesh cover based on finite element method |
| CN109145514A (en) * | 2018-09-30 | 2019-01-04 | 浙江中科电声研发中心 | A kind of Numerical Simulation Analysis method of loudspeaker distortions |
| CN110442907A (en) * | 2019-07-02 | 2019-11-12 | 浙江中科电声研发中心 | The Numerical Simulation Analysis method of piezoelectric type MEMS loudspeaker fundamental characteristics |
| CN110442907B (en) * | 2019-07-02 | 2023-04-28 | 浙江中科电声研发中心 | Numerical simulation analysis method for basic characteristics of piezoelectric MEMS loudspeaker |
| CN111770233A (en) * | 2020-06-23 | 2020-10-13 | Oppo（重庆）智能科技有限公司 | Frequency compensation method and terminal equipment |
| CN112487679A (en) * | 2020-11-20 | 2021-03-12 | 四川湖山电器股份有限公司 | Method, system, terminal and medium for simulating acoustic characteristics of sound box by numerical values |
| WO2022127081A1 (en) * | 2020-12-14 | 2022-06-23 | 苏州上声电子股份有限公司 | Coaxial loudspeaker with horn and shape optimization method therefor |
| CN113297726A (en) * | 2021-04-29 | 2021-08-24 | 益阳市信维声学科技有限公司 | Method for generating magnetic induction intensity curve of loudspeaker and terminal |
| CN113286233A (en) * | 2021-05-20 | 2021-08-20 | 维沃移动通信有限公司 | Loudspeaker simulation method, loudspeaker simulation device, loudspeaker and electronic equipment |
| CN116095579A (en) * | 2023-04-07 | 2023-05-09 | 张家港市玉同电子科技有限公司 | Harmonic wave processing method and system of ceramic loudspeaker |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104408227A (en) | Loudspeaker distortion feature value simulation analysis method | |
| CN109145514A (en) | A kind of Numerical Simulation Analysis method of loudspeaker distortions | |
| CN102004823B (en) | Numerical value simulation method of vibration and acoustic characteristics of speaker | |
| CN104252559B (en) | A kind of Numerical Simulation Analysis method of loudspeaker multi- scenarios method | |
| CN110427650A (en) | The Numerical Simulation Analysis method of moving iron type loud-speaker fundamental characteristics | |
| CN110188428B (en) | Loudspeaker joint simulation method based on finite element method | |
| Xu et al. | Analysis of sound pressure level of a balanced armature receiver considering coupling effects | |
| Wu et al. | Modelling, calculation and analysis of electromagnetic force and vibroacoustic behavior of integer-slot permanent magnet synchronous motor considering current harmonics | |
| Nielsen et al. | Estimation of optimal values for lumped elements in a finite element—Lumped parameter model of a loudspeaker | |
| Jiang et al. | Design and analysis of watch speaker to enhance waterproof performance by using liquid silicone rubber side diaphragm | |
| Klippel | Modeling the large signal behavior of micro-speakers | |
| Hill | Loudspeaker Modelling and Design: A Practical Introduction | |
| Hwang et al. | Analysis of harmonic distortion due to uneven magnetic field in a microspeaker used for mobile phones | |
| Hwang et al. | New development of combined permanent-magnet type microspeakers used for cellular phones | |
| CN102968543B (en) | A kind of Numerical simulation on temperature characteristics method of loudspeaker voice coil and magnetic circuit | |
| Novak | Measurement of loudspeaker parameters: A pedagogical approach | |
| Neri et al. | A novel micromachined loudspeaker topology | |
| Chao et al. | Magneto-electrodynamical modeling and design of a microspeaker used for mobile phones with considerations of diaphragm corrugation and air closures | |
| JP7113168B2 (en) | Sound pressure calculation method and sound pressure calculation program | |
| Chao et al. | Dynamical modeling and experimental validation of a micro-speaker with corrugated diaphragm for mobile phones | |
| Lee et al. | Analysis of total harmonic distortion in microspeakers considering coupling effect | |
| Sun et al. | Lumped element multimode modeling for a simplified balanced-armature receiver | |
| Cao et al. | A novel and high efficient simulation model of loudspeaker | |
| WO2017220816A1 (en) | Method for simulating total harmonic distortion of a loudspeaker | |
| Hwang et al. | New development of integrated microspeaker and dynamic receiver used for cellular phones |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20150311 |
|
| WD01 | Invention patent application deemed withdrawn after publication |