請教LC濾波器的設(shè)計(jì)
我想用lc濾波器將峰值300v的spwm波平滑成正弦波,請問如何設(shè)計(jì)?
spwm方波的頻率為1.6k,
請教LC濾波器的設(shè)計(jì)
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let me give u a hand
lc filter's transfer function is a two order system,so u can achieve it's corner frequency which should be 1/7~1/10 of your spwm frequency,
here your spwm frequency equals to switching frequency,but 1.6k is a bit low from my opinion,how to eliminate your switch noise under such a low frenquecy?
lc filter's transfer function is a two order system,so u can achieve it's corner frequency which should be 1/7~1/10 of your spwm frequency,
here your spwm frequency equals to switching frequency,but 1.6k is a bit low from my opinion,how to eliminate your switch noise under such a low frenquecy?
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@
letmegiveuahandlcfilter'stransferfunctionisatwoordersystem,soucanachieveit'scornerfrequencywhichshouldbe1/7~1/10ofyourspwmfrequency,hereyourspwmfrequencyequalstoswitchingfrequency,but1.6kisabitlowfrommyopinion,howtoeliminateyourswitchnoiseundersuchalowfrenquecy?
go on
how to achieve your L and C is often up to your experience.u can get L value first,or C first,use this value to get the other varialbe's value,here below is an example:
1) C value
accordding your inverter output current maxsimum value ,caculate the current value flowing the capacitor,then use the formula C=dU/dI,so C can be achieved.
2)L value
if C has been choosed,then u can use the corner frequecy to get your L value,
corner frequecy can be depicted as following:
f=1/[2*pi*sqr(L*C)],
usually f equal to 1/5~1/10 of fs(switching frequency).
now C and f has been calulated,so use the above formula,L can be drawn out.
by the way,much experience determines your choice for this two parameters.
contact me if still any questions
how to achieve your L and C is often up to your experience.u can get L value first,or C first,use this value to get the other varialbe's value,here below is an example:
1) C value
accordding your inverter output current maxsimum value ,caculate the current value flowing the capacitor,then use the formula C=dU/dI,so C can be achieved.
2)L value
if C has been choosed,then u can use the corner frequecy to get your L value,
corner frequecy can be depicted as following:
f=1/[2*pi*sqr(L*C)],
usually f equal to 1/5~1/10 of fs(switching frequency).
now C and f has been calulated,so use the above formula,L can be drawn out.
by the way,much experience determines your choice for this two parameters.
contact me if still any questions
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@
goonhowtoachieveyourLandCisoftenuptoyourexperience.ucangetLvaluefirst,orCfirst,usethisvaluetogettheothervarialbe'svalue,herebelowisanexample:1)Cvalueaccorddingyourinverteroutputcurrentmaxsimumvalue,caculatethecurrentvalueflowingthecapacitor,thenusetheformulaC=dU/dI,soCcanbeachieved.2)LvalueifChasbeenchoosed,thenucanusethecornerfrequecytogetyourLvalue,cornerfrequecycanbedepictedasfollowing:f=1/[2*pi*sqr(L*C)],usuallyfequalto1/5~1/10offs(switchingfrequency).nowCandfhasbeencalulated,sousetheaboveformula,Lcanbedrawnout.bytheway,muchexperiencedeterminesyourchoiceforthistwoparameters.contactmeifstillanyquestions
can u explain about c=DU/DI,for example?
tks
tks
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@morel
canuexplainaboutc=DU/DI,forexample?tks
sorry,made a mistake
i=Cdu/dt
u=Um*sin(w*t),
then,
Im=Um*C*w,
so C=Im/Um*w,
if u=Umsin(2*pi*50*t)
so,i=Um*C*2*pi*50*cos(2*pi*50*t)
Im=Um*C*2*pi*50
from the above,
C=Im/Um*2*pi*50
sorry,i can't remember clearly how to determine the value of the Im,maybe it's 1/n of the output current max value.I can tell u more if I find out where my material is
i=Cdu/dt
u=Um*sin(w*t),
then,
Im=Um*C*w,
so C=Im/Um*w,
if u=Umsin(2*pi*50*t)
so,i=Um*C*2*pi*50*cos(2*pi*50*t)
Im=Um*C*2*pi*50
from the above,
C=Im/Um*2*pi*50
sorry,i can't remember clearly how to determine the value of the Im,maybe it's 1/n of the output current max value.I can tell u more if I find out where my material is
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letmegiveuahandlcfilter'stransferfunctionisatwoordersystem,soucanachieveit'scornerfrequencywhichshouldbe1/7~1/10ofyourspwmfrequency,hereyourspwmfrequencyequalstoswitchingfrequency,but1.6kisabitlowfrommyopinion,howtoeliminateyourswitchnoiseundersuchalowfrenquecy?
我用單片機(jī)控制
頻率升不上去,定時(shí)中斷受限,請問有什么好辦法嗎?
頻率升不上去,定時(shí)中斷受限,請問有什么好辦法嗎?
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@
letmegiveuahandlcfilter'stransferfunctionisatwoordersystem,soucanachieveit'scornerfrequencywhichshouldbe1/7~1/10ofyourspwmfrequency,hereyourspwmfrequencyequalstoswitchingfrequency,but1.6kisabitlowfrommyopinion,howtoeliminateyourswitchnoiseundersuchalowfrenquecy?
請問至少多大頻率可以消除開關(guān)噪音
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@whualei
我用單片機(jī)控制頻率升不上去,定時(shí)中斷受限,請問有什么好辦法嗎?
oh
80c196 or tms320f240x DSPs.
when I stayed in college,f240DSP was very popular,20k fs was easily acchieved as well as PWM generator.but an obvious demerit was such that the A/D converter was not very good as expected anyway.
a guy realized pure sinusoidal output with one dsp and operation amplifier(even parallel operation was acchieved).the THD is below 0.5% even with diode rectifier load. and attracted much attention ,including lite-on corp. ,and so on
80c196 or tms320f240x DSPs.
when I stayed in college,f240DSP was very popular,20k fs was easily acchieved as well as PWM generator.but an obvious demerit was such that the A/D converter was not very good as expected anyway.
a guy realized pure sinusoidal output with one dsp and operation amplifier(even parallel operation was acchieved).the THD is below 0.5% even with diode rectifier load. and attracted much attention ,including lite-on corp. ,and so on
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@
sorry,madeamistakei=Cdu/dtu=Um*sin(w*t),then,Im=Um*C*w,soC=Im/Um*w,ifu=Umsin(2*pi*50*t)so,i=Um*C*2*pi*50*cos(2*pi*50*t)Im=Um*C*2*pi*50fromtheabove,C=Im/Um*2*pi*50sorry,ican'trememberclearlyhowtodeterminethevalueoftheIm,maybeit's1/noftheoutputcurrentmaxvalue.IcantellumoreifIfindoutwheremymaterialis
我看到一本書上取的是1/2,不過我認(rèn)為可以取到1/4.
The value of the Im is 1/n of the output current max value.The number n may set to 2 to 4.I think.
The value of the Im is 1/n of the output current max value.The number n may set to 2 to 4.I think.
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