功率器件的散热计算及散热器选择

..,?.Tj.Tj,.125~200,85()..,.,.,,..,.RRI2[W]RI26.33..U1-U2=IRT1-T2=PRT(1-1)T1-T2,P,RT,/W.RT.Tj,Ta,PCMRTTj-Ta=PCMRT(1-2)(25),Tj,,PCM...1-1(a).(J-Junction)(A-Ambient):(J)(C-Case),(A);(S)().(),..,1-1(b).Pc;Tj,Ta;Rjc,Rca,Rcs,Rsa,.1-1(a)(b),,RT=Rjc+Rca(1-3),Rcs+RsaRca,RTRjc+Rcs+Rsa(1-4)Rjc,MJ21195Rjc=0.7/W,MJE15034Rjc=2.5/W.Rca.Rsa().,,.1-2,.CAAS(a)JRjcRcsRsaRcaSCAJTjTaPc(b)Rcs..,..(),.0.05~0.1mm.RT,TA(1-2).().,.(),.(),.1-2()()RjcRcsRsaRja=Rjc+Rcs+RsaPDTjTARjaRja≤(Tj-TA)/PDRsaRsa≤[(Tj-TA)/over(PD)]-(Rjc+Rcs)Tj125TA=40~60RjcRcsRcs0.1~0.2/W;Rcs1/WPDRsaRsa100A(cm2)Rsa()1050710251021031011.5m/sbadA=a*bcm2d1.5mmRT------/WRjc------/WRcs------/WRsa------/WTj------Tc------Ts------TA------PD------WΔTsa------:Rsa=(Tj-TA)PD-Rjc–RcsRsaTjRjcPDRcs1RT:RT=(Tjmax-TA)PD2RsaΔTsaRsa=RTRjcRcsΔTsaRsa×PD3RsaΔTsaPDRsaΔTsaΔTsaαα7.2ψ1ψ2ψ3{√√[(Ts-TA)20]}ψ1───L/bαLbψ2───h/bαhψ3───Wα√√[(Ts-TA)20]───αq0q0=α×ΔTsa×2h+b×Ln,PD′PD′nq0PD′2nq0PD′PD()10~15%3%500~800VPA02(APEX)18TO-3:Vs18V;RL45kHz40PA02:IQ27mA40mA;Rjc()2.4/W2.6/WPD:PD=PDQ+PDOUTPDQPDOUTPDQ=IQ(Vs+|-Vs|)PDOUT=Vs2/4RL:PD=IQ(Vs+|-Vs|)+Vs2/4RL=37mA(36V)+182V/4×4=21.5821.6W37mARsa:Rsa≤({Tj-TA}/over{PD})-(Rjc+Rcs)Tj125TA40Rjc(Rjc=2.6/W)Rcs0.2/W(PA02):Rsa≤[{125-40}\over{21.6W}]-(2.6/W+0.2/W)≤1.135/WHSO40.95/W1.;15012525()2.()3.()4.5.()6.(),PCM,.,PCM,3AD1TA=25Tj=85Rjc=3.5/W,1201203mm3,?50120120mm2=14400mm2=144cm2Rsa=3.5/WRcs=0.5/WRTRjc+Rcs+Rsa=(3.5+0.5+3.5)/W=7.5/WPCMRTTjTA.:RTPCM=Tj-TA:PCM=(Tj-TA)/RT=(85-25)/7.5/W=8W,1W8W.,,,.50PCM50=(Tj-TA)/RT=(85-50)/7.5/W=4.7W,PCM.:YCZ8-25-6-H:H---;Y---()(mm)Cλ,W/mρ,g/cm3