E N D
1. Flyback????????????
2. ??????
4. ?????Np?Ns?Lp??? 1?????Np
Vin=Np*(?f/?t)=Np*(?BAe/Ton)
=»Np=VinTon/?BAe ????(1)
?B?0.65Bs(??Bs???0.5T)
=»?B=0.32T
Vin????????
Ton=dmax*T
5. 2.???? ??????????????????????
VinTon/Np=VsToff/Ns =»
Ns=(VsToff/VinTon)*Np
=[Vs (1-dmax)/Vindmax]*Np
(2)
6. 3.?????Lp ?????????
??????
Vin=Lp*(Ipmax/Ton)
(3)
=> Lp=VinTon/Ipmax
(4)
? Pin=1/2LpIpmax^2* f
=1/2(VinTon)Ipmax*f
=> Ipmax=2Pin/VinTon*f
(5)
7. ?(5)??(4)
Lp=(VinTon)^2*f/2Pin
=Vin^2*T^2*dmax^2*f/2P
=Vin^2*dmax^2/(2Pin*f)
=?Vin^2*dmax^2/(2Po*f)
(6)
8. ???????????Lg 1/2Lp*Ipmax^2=1/2?B*H*Vg
(Vg?????=Lg*Ae)
??:΅?*H=?B/0.4p???΅?=1
=> H=?B/0.4p
(7)
?(7)????:
Lp*Ipmax^2=?B^2AeLg/0.4p
=> Lg=0.4pLp*Ipmax^2/(Ae?B)
(8)
9. ?????Vce?Ic???(???) Vce=Vin+nVs (n=Np/Ns)
(9)
?(2)???Vs=(1/n)*[Vindmax/(1-dmax)]
=>Vce=Vin+Vindmax/(1-dmax)
=Vin/(1-dmax)
(10)
?(5)?:Ic=Ipmax=2Po/?Vindmax
(11)
???Icrms=(Ton/3T)^1/2*Ipmax
=(dmax/3)^1/2*Ipmax ?dmax=0.4
=> Icrms=0.37*Ipmax
10. ?.???????Id?Vd??? Id=Ismax=n*Ipmax
??????,?????????????????????Io,???????Id?Io????
11. ???
12. ???:
Io=1/2*Ismax*toff
=>Ismax=2Io/(1-dmax)
=>Id=Ismax=2Io/(1-dmax)
(14)
Vd=Vo+Vin/n
(15)
??:Ipmax???Io???
Ipmax=Id/n=2Io/(1-dmax)*(1/n)
(16)
13. ????????????Ipmax????????????Ismax??
14. Ipmax=(N2/N1)*Io/[(1-dmax)]+ (Vin /2 LpF)dmax
(17)
VinTon=Lp(Ipmax-Ipmin)
=>Ipmax=VinTon/Lp+Ipmin
(18)
½(Ismax+Ismin)Toff=IoT
Ismax+Ismin=2IoT/Toff=2Io/(1- dmax)
(19)
VsToff=L2(Ismax-Ismin)
VsToff/N2=VinTon/N1
=>Ismax-Ismin=(VinTon/L2)*(N2/N1)
?Lp/L2=N1^2/N2^2
=>Ismax-Ismin=(VinTon/Lp)*(N1/N2)
(20)
15. (19)-(20)??:
Ismin=Io/(1- dmax)- (VinTon/2Lp)*(N1/N2)
(21)
Ipmin=Ismin*N2/N1=(N2/N1)*Io/(1- dmax)-
VinTon/2Lp
(22)
?(22)??(18):
Ipmax=VinTon/Lp+{(N2/N1)*[Io/(1- dmax)]-
Vin/2Lp}
=(N2/N1)*[Io/(1- dmax)]+VinTon/2LpF
=(N2/N1)*[Io/(1- dmax)]+Vin dmax/2LpF
????????Id=Ismax=N1Ipmax/N1
=1/(1- dmax)*Io+(Vin dmax/2LpF)*(N2/N1)
(23)
16. Flyback???????? ??????C?????Ic=I2- Io
??:I2???????
Ic??????????:
Icrms=[Ton/3T(I2p^2-I2pIo+Io^2 )+(Toff/T)*
Io^2]^1/2
??I2p=2io/(1- dmax)
???????????????????