临界连续电流模式Flyback设计范例(85W)

85W DCMB Flyback Loss Analysis ProgramNote: This programme is wrote for magnetic design and power loss calculation of DCMB Flyback with Schottky Diode RectificationBrain Yang 2009.12.29Meg 106:=k 103:=u 106−:=n 109−:=p 1012−:=Permeability of air(H/m):1. Electrical Specifications:V in_nom 450:=Normal DC Input Voltage(V)[0<x<500V]:--- Output Definition ---V o_nom 43:=Normal Output Voltage(V)[0<x ]:ΔV o 500m:=Output Voltage Ripple(V)[0<x=<Vo_nom*10% ]:I o_nom 2:=Normal Output Current(A)[0<x ]:--- Design Specification ---Estimated Rectifier Voltage Drop [0<x=<2 ]:V est.Rec 0.4:=Ambient Temperature (deg.)[0=<x=<100 ]:T a 25:=Transformer's Efficiency[80%=<x=<100%]:ηTrans 0.95:=Total Efficiency:η0.92:=Maximum Output Power(W):P o V o_nom I o_nom⋅:=P o 86=2. Operating Condition Design:2.1 Turn Ratio Selection and Voltage Stress Set:* Before select the turn ratio, we assumed that 800V MOSFET is used in primary and 200V Schottky Diode is used in secondary.* The assumation of voltage stress can be estimated according to input and output voltage. n set 4:=Turn Ratio Set:Primary Max Bus Voltge:V in_max 460:=Supposed Primary Spark in Highest DC Input:V pri_spark 60:=Secondary Max Bus Voltge:V out_max 44:=Supposed Secondary Spark in Highest DC Input:V sec_spark 10:=Primary MOSFET Voltage Stress:V ds_max_Q1V in_max n set V out_max V est.Rec +()⋅+V pri_spark+:=V ds_max_Q1697.6=Secondary Rectifier Voltage Stress:V diode 168.4=* if V ds_max_Q1 and V diode within the SPEC of the components selected, OK if not, reset the n set2.2 Transformer Core Design:2.2.1 Select Core: PQ3220Window Area(m^2) :A w 48106−⋅:=Effective Cross Section Area (m^2):A e 169106−⋅:=Cross Section Area Of Center Leg(m^2) :A c 143106−⋅:=Magnetic Path Length (m):l e 55.9103−⋅:=Effective Volume(m^3) :V e 9440109−⋅:=Height Of Window(m) :W h 8.9103−⋅:=Width Of Window(m) :W w 5.4103−⋅:=Mean Length Turn(m) :MLT 66.9103−⋅:=2.2.2 Select Core Materials: NC-2HM5/ NICERAμi 2300:=C t0 4.2061:=C t10.065:=C t20.00032938483:=B s 0.41:=xx 1.37276:=yy 2.51937:=C m 2.65901:= 2.3 Duty Cycle Calculation:D 0.278= 2.4 Assuming Switch Frequency:fsa 65k⋅:=2.5 Primary Lp Calculation:Ipk_p 1.445=Lp 1.334103−×=2.6 Revise Switching Frequency(Hz):1. Ton:Ton 4.283106−×=2. Vds rise time TLeak:Cp 200.001012−⋅:=TLeak 9.46108−×=3. Toff:Toff 1.11105−×=4. Vds fall time Tw:Tw 1.622106−×=f s 5.847104×= 2.7 Bmax Selection:Bmax 0.24:=ΔB Bmax:=ΔB 0.24=2.8 Transformer Design:2.8.1 Transformer Primary Turns[1=<x]:N_pri Trans 47.517=Np select:Np 48:=2.8.2 Transformer Secondary Turns[1=<x]:Ns select:Ns 12:=2.8.3 Select Winding:Allowed Temperature Rise (deg.)[0<x]:Tr Trans 80:=Resistivity Of Copper (oohm.m):ρcu T a Tr Trans , () 1.557108−⋅10.0043T a Tr Trans +()+⎡⎣⎤⎦:=ρcu 2.26108−×=Select WindingTransformer Secondary Wire Diameter:Dcu_sec Wire 0.5103−⋅:=Transformer Secondary Wire Strands:Nst_sec Litz 4:=Transformer Primary Wire Diameter:Dcu_pri Wire 0.1103−⋅:=Transformer Primary Wire Strands:Nst_pri Litz 10:=2.9 Current Calculation:================ Primary Current@Vin======================================Transformer Primary Average Current(A):Iave_p 0.201= Transformer Primary Peak Current(A):Ipk_p 1.445= Transformer Primary Current Ripple(A):ΔIp Ipk_p:=ΔIp 1.445= Transformer Primary RMS Current(A):Irms_p 0.44= Transformer Primary DC Current(A):Idc_rms_p Iave_p:=Idc_rms_p 0.201= Transformer Primary AC Current(A): Waveform of Primary Current:================ Secondary current@Vin======================================D20.649= Transformer Secondary Average current when DIODE is on(A):Iave_duty_s 3.081= Transformer Secondary Peak current(A):Ipk_s 6.162= Transformer Secondary current ripple(A):ΔIs Ipk_s:=ΔIs 6.162= Transformer Secondary RMS current(A):Irms_s 2.866= Transformer Secondary DC current(A):Idc_s I o_nom:=Idc_s 2= Transformer Secondary AC current(A):Iac_s 2.053=Waveform of Secondary Current:3. Transformer Loss Calculation:3.1 Core Loss Calculation:3.2 Winding Loss Calculation:Rdc_pri Trans 0.915=Rdc_sec Trans 0.023=Kac 3:=Transformer Primary Winding Loss(W):Ploss_pri Kac Irms_p 2⋅Rdc_pri Trans⋅:=Ploss_pri 0.532=Transformer Secondary Winding Loss(W):Ploss_sec Kac Irms_s 2⋅Rdc_sec Trans⋅:=Ploss_sec 0.569=Transformer Winding Loss(W):Ploss_wire Ploss_pri Ploss_sec+:=Ploss_wire 1.101=Transformer total loss(W):Ploss_trans Ploss_wire Ploss_core+:=Ploss_trans 1.527=4. Primary MOSFET Loss:=============Mosfet Data From Datasheet(SPP11N80C3)=============Drain_Source On_State Resistance(ohm):Rds_on Mos0.45:= Gate Threshold Voltage(V):Vgs_th Mos3:= Transconductance(S):gfs Mos7.5:= Input Capacitance(F):Ciss Mos1600p:= Output Capacitance(F):Coss Mos800p:= Reverse Transfer Capacitance(F):Crss Mos40p:= Effective Output Capacitance(F) Energy Related:Coss_er Mos44.3p:= Effective Output Capacitance(F) time Related:Coss_tr Mos33.9p:= Gate To Source Charge(C):Qgs Mos6n:= Gate To Drain Charge(C):Qgd Mos25n:= Gate Charge Total(C):Qg Mos50n:= Mosfet Current @2*Vgsth(A):Id_2Vgsth Mos16:= Rds_On VS Temperatur Coefficient1:BR10.011:= Rds_On VS Temperatur Coefficient2:BR20.562:=============Mosfet Driver==================Driver voltage @turn on (V)[ 5V=<x<20V]:Vdr_on Mos15:= Driver voltage @turn off (V)[ -20v=<x<=0v]:Vdr_off Mos0:= Driver resistance @turn on (ohm)[ 0<x<100]:Rdr_on Mos10:= Driver resistance @turn off (ohm)[ 0<x<100]:Rdr_off Mos 2.2:= Primary MOSFET temperature arise : Tr Mos80:=Primary MOSFET Rds_on coefficient : Nor_Rds Temp:=+()BR1Temp⋅BR2 4.1 Mosfet Output Capacitance Discharge Loss when Mosfet Turn On :Voltage Across The Switch When Turning Off:V in_on 278.149=C ext 10p:=Ploss Mos_cap 0.565=4.2 MOSFET Conductance Loss:Ploss_con Mos Irms_p 2Rds_on Mos Nor_Rds T a Tr Mos +()⋅()⋅:=Ploss_con Mos 0.15=4.3 MOSFET Turn Off Loss:MOSFET Switching off Procedure:tf_Q180109−⋅:=V ds_Q1_pk V in_off V pri_spark+:=V ds_Q1_pk 681.851=Ploss_off Mos 0.384=4.4 MOSFET Driving Loss:Ploss_dr Mos Qg Mos Vdr_on Mos ⋅f s⋅:=Ploss_dr Mos 0.044=4.5 MOSFET Loss Summary:Ploss Mos Ploss Mos_cap Ploss_con Mos +Ploss_off Mos +Ploss_dr Mos+:=Ploss Mos 1.143=5. Secondary Rectifier Diode Loss:Diode: V20200CT junc 60:=VF 0.5:=The Secondary Rectifier Diode loss(W):Ploss Diode I o_nom VF⋅:=Ploss Diode 1=6. Primary Sense Resistor Loss:Rs_pri 0.25:=Prs_pri Irms_p 2Rs_pri⋅:=Prs_pri 0.048=7. Secondary Sense Resistor Loss:Rs_out 0.03:=Prs_out I o_nom 2Rs_out⋅:=Prs_out 0.12=8. RCD Clamp Loss:The Capacitance of the Snubber(F)[0<x]:C calmp 4.7109−⋅:=The Resistance Inductance(ohm)[0<x]:R clamp 200k⋅:=Vclamp_cap_rms n set V o_nom⋅:=The Loss On Rsnubber(w):Ploss_clamp 0.148=9. Output Capacitor Loss:Nichicon: 220uF/63V Φ10*20 PW 105℃Esr C_co 0.147:=C co 680u:=Npar C_co 2:=Power Loss On Capacitance :Ploss_c_output Iac_s 2Esr C_co⋅:=Ploss_c_output 0.31=10. Control Loss:1. The Primary Auxiliary Power Loss:Vcc127:=Icc115103−⋅:=Pvcc1Vcc1Icc1⋅:=Pvcc10.405=2. The Secondary Auxiliary Power Loss:Vcc227:=Icc24103−⋅:=Pvcc2Vcc2Icc2⋅:=Pvcc20.108=11. Summary :=Ploss_trans 1.527=Ploss Mos 1.143Ploss Diode1==Prs_pri0.048Prs_out0.12==Ploss_clamp0.148=Ploss_c_output0.31=Pvcc10.405=Pvcc20.108+Pvcc1+Pvcc2 :=++Ploss_c_output+Ploss_clamp+Ploss DiodePtotal_loss Ploss_trans Ploss Mos+Prs_out+Prs_pri=Ptotal_loss 4.809ηtotal0.947=。