RCC转换式电源设计方案

670258477.xls變壓器設計出力P(out)=V(out)*I(out)出力電壓V(out):5.25V出力電流I(out):0.50A出力功率P(out):2.63W過電流保護I(ocp):0.60AOCP:OverCurrentProtect效率設定80.00%(一般設在65%~80%取70%)入力P(in)=P(out)/效率=

3.28 Watt入力最大電壓Vin(max)=264.00V入力最小電壓Vin(min)=90.00V入力平均電流Iin(avg)=Pin/Vdc(min)Vdcin(max)=Vac(min)*1.2P(in)=3.28WVDCin(min)=108.00VI(in)=0.03A設在最低入力時,定格負載的動作週期t=40.00SWITCH頻率f=45.00

%KhzT=1/f=22.22uSTon=Toff=(duty*T)=8.89uS一次側電流I(peak)=2*Iin(平均)/duty=0.15A[1of14]670258477.xls一次側電感Lp=VinDC(min)*Ton/I(peak)=6,319.54uH=6.32mH依表選擇鐵芯:0.21有效截面積Ae=cm2動作磁通Bm=2,500.00G一次側卷線182.86出力電壓V(out):5.25Np=(Ipeak*Lp)/(Ae*Bm)*10^8=(T)183.00(T)回掃電壓二次側卷線Vflyback=二次側二極体VF(压降）約:0.55V=Ns=(Vout+VF)/(Vflyback)*Np=14.73(T)取Ns15.00(T)實際取值Np=輔助電壓卷線計算11.00反推Vflyback=輔助電壓VB取V則VinDC(min):Np=VB:NB=輔助電壓卷線:NB=18.62(T)取NB=19.00(T)晶體的實際最高電壓Vce(max)Vf線徑之決定:=設電流密度為:5.00A/CM2(一般設定為6A/CM2)實際Duty=Vflyback/(V一次側線徑選擇:=Ip(rms)=(duty/3)1^2=0.06A&=I/(3.14*D^2/4)>>>>I=Ip(rms)實際一次測電流I(peack)'2*I一次側銅線直徑:DP=(I(rms)*4/3.1416*6)1^2=0.12mm二次側線徑選擇:實際TonLp*Ipeack/VIs(rms)=Is(peak)*(duty/3)(1^2)=2*Io*(duty/3)^1/2))/dutyIs(rms)=0.91A二次側銅線直徑:DS=(I(rms)*4/3.1416*6)1^2=0.44mm實際工作頻率f'duty/Ton=若要並繞則選擇0.31mm兩條並繞實際工作磁束密度Bm[2of14]670258477.xls輔助線圈NB線徑取0.20mm即可橋式整流D1選擇:Pin=3.28WattIin(ac)=Pin/Vin(ac)*cosO一般取COSO=0.65Iin(ac)=0.06A逆向耐壓選擇>2VinDC(max)約為:739.20VD2為加速起動二極体ROHNVRIoVF75V150mA1.2VD3為輔助C6放電及穩定輔助電壓稽納,一般在2.0V～5.0VD4,D5為撿知稽納:設VDC(out)=5.25VPHC之VF=1.20V流經R8電流為5.00mA取R8=47.00OhmVD4+VD5=Vout-Vphc(DF)-Vr8=3.82V取D4=D5=1.91V之稽納Vz:5.08～5.37VD6之選擇:Po(Loss):500.00mWD7之選擇:Io>Is(rms)>0.91AVR>((Vo加VF)*Np*1.2)/Ns加VinDC(max)*1.4=454.45VD8為過電壓保護稽納:[3of14]670258477.xls一般在異常情況呈短路狀況其使用1W之稽納其稽納電壓約在Vout(max)以上TH1之選擇:二次電容耐壓以下設突入電流最大值為30.00A則Rth=Vindc(max)/Irush=12.32OhmL之選擇:視EMI特性耐電流>Iinac=0.06AC1之選擇:視EMI特性耐電流>Iinac=0.06AC2為EMI電容,一般用俗稱X電容,耐壓>=125V有安規承認之電容設洩漏電流為0.25mA,則Ileak=0.25mA=>>>Vinac(max)\(1/WC)C=2,511.91Pf,取C=4,700.00Pf電容則Iu=0.47mA預設值0.25mAC3電容之選擇:設入力90.00V仍能穩壓實際為110.00VC=2*(Po*t)\(效率*(Vin實際2-Vin(min)^2))C3=>>>10.13uF以上Q1之選擇Ic>2Ipeak>0.30AVce>(Vo+Vf)*Np*1.2/Ns+264.00*1.4Vce>454.45VR5,R6之選擇:R5+R6<=(VB-VBE-VFD2)/IB>>(VB-VBE-0.6*2)/(Ipeak/hfemin)[4of14]670258477.xlsV=VinDC(min)*N/N=11.22VBBP(min)VBE設定1.50Vhfe設為10.00VFD2設定0.60VR5+R6<=560.98ohm最大入力時之dutyVinduty(max)=(Vo+VF)/2*(Ns/Np)*Vind(max)=0.06WattVB(max)=0.10WattVinDC(max)*NB/NP=38.40V設R5+R6=24.00Ohm下IB=1.49APr=2.54WattR2啟動電阻之計算:故選擇R5=R6=12.00OhmVBE<NB*((Po*RL)1^2-VF)/NS5.08Watt,OhmVBE<NB*V2/NSPo=1/2*Lp*Ipeak*Ipeak*fIpeak=IB*hfeIB=VB/R5,6Ipk=NB*Vin*hfe/(Np*R5,6)T=VBE*C5/Is==>Is=Vin/R2且f=1/Tf=Vin/(VBE*C5*R2)VBE<NB*((Po*RL)1^2-VF)/NSVBE<NB/Ns*((NB*hfe*Vin)/(Np*Rb)*(Lp*Vin*RL/(2*VBE*C5*R2)1^2-VF))R2<(V*Ns/N+V)<(NB*hfe*Vin/np*rb*(Lp*Vin*RL/2*V*C5*R2)1^2BEBFBELP*Vin*RL/((VBE*NS/NB+VF)*NP*RB/(NB*hfe*VIN))^2C5設定為0.10uFA=Lp*Vin*RL=7,166,361.60B=(VBE*Ns/NB+VF)=1.73C=NP*RB/(NB*hfe*Vin)=0.21R2<D=2*vbe*c5=0.30[5of14]670258477.xlsPr=Vinmax^2/R2=173,652.96KOhm設定R2=470.00KOhmC5之確認:0.29Watt取0.58Watt設起動時間50.00mS以下50.00mS>R2*C5R9之決定:C5<0.00uFVc=VF*1.2=(Vo+VFD6)/Ns*Np*1.2Vc=94.35VPR9=3%*Pout=0.08Watt取0.16Watt電阻R9=Vc*VC/PR9=113.05Kohm取33.00KOhmC9>>T/R=673.40Pf取1,000.00PfC4為提升電晶体之動作速度,一般在1000Pf以下故選擇470.00PfC9的耐壓>2*Vc>188.71V耐壓>(Vo+VF)/Ns*Np*1.2+Vindc(max)R3的一般選擇: > 401.65 V,,一般取 1.00 KV的耐壓T=R3*C4<TonC6,C7為旁路電容一般在R3<Ton/C<18.91KOhm,一般取1.00KOhm以下2W電阻R4為C6之放電電阻一般選擇0.10uF以下[6of14]670258477.xlsC8電容之選擇:100.00Ohm,左右1/4Watt漣波電流Ir=((1+(4*T(on)/T(off))/3))1^2*1.3Ir=1.79AIr=120Hz(ripple)*Kt(溫度係數)*Kf(頻率係數)設定:120Hz(ripple)=1.00AKt(溫度係數)=1.75Kf(頻率係數)=1.08Ir=1.89A,必須大於1.79AESR=1/(2*3.14*f*C)*tan&=120Hz的ESR設定C8=2,200.00uF,tan&=0.16ESR=0.10Ohm50.00K時之Xc=0.00OhmZc=(ESR^2+(1/Wc)^2)^(1/2)=0.10Ohm追加LC濾波器:Vripple=Ipk*Zc=2*Io/duty*Zc=0.24V設輸出漣波最大50.00mV則20log(50.00除以500.00)=(20.00)dB(衰減量)設LC特性為12.00dB/Oct下降K=1.67Octfc<(1/(2)^k)*Swf<12,599.21C10>1/((2*3.1416*fc)^2*L)>>10.00uF[7of14]670258477.xls設定L2=10.00uHC10>>0.16PHC之選定:選擇有UL認可之PHCTLP521-1R1為C1放電電阻,一般取200.00KOhmPR1=Vinac^2/R1=0.35WattQ2為控制晶体一般選用速度較快之小型控制晶体由於安全距離限制,一般取0.5Watt電阻Ic>>2*IB以上,一般取1.00A左右Vce>>2*VB>>22.44V以上[8of14]670258477.xls[9of14]出力電流 I(out) :

670258477.xls0.50 ATon/Toff*Vdcin(min)72.00 V103.00NS=7.00Lp=5,000.00uHVflyback=(Vout+VF)*Np/Ns85.34V體的實際最高電壓Vflyback+Vdcin(max)458.64VDuty=Vflyback/(Vflyback'+VD