27-2 Diode Snubber Circuit: di-/dt and dip/dt are determined by external circuitdidir trRdtdt S+1Qrr=lrrtrr/2dir/dt0.25lrrdi-/dtVonVFPt5St4
27-2 Diode Snubber Circuit 4 dt S +1 t = dt di di I = R t R rr rr • diF/dt and diR/dt are determined by external circuit. IF diF/dt Vrr t3 t2 t1 t5 VFP t Von 0.25Irr trr Qrr=Irrtrr/2 t 5 t 4 S= t Irr VR t4 diR/dt
27-2 Diode Snubber Circuit2 The cause of overvoltagesThe overvoltages occur due to the stray or leakageinductance Lin series with the diode and the snap.offofthe diodereverse recovery current.VddipfdtLo+1oipr(t)VdD,本 VD+Vpr(t)SwDiodevoltagediLwithoutsnubberdtLg=strayinductance
2 The cause of overvoltages The overvoltages occur due to the stray or leakage inductance Lσ in series with the diode and the snapoff of the diode reverse recovery current. 27-2 Diode Snubber Circuit Lσ =strayinductance - + Df L Vd Io Sw - vD + Irr dt L = Io t t iDf(t) Diode voltage without snubber L dt diL Df v (t) diDf Vd Vd
27-2 Diode Snubber Circuit3overvoltageprotectionIntroducing a Rs-Cs snubber circuit+0RTherolesofelementsVdDt±Cs的作用是限制Dt上的dvldt和关Cs断过电压；SwsnubberRs的作用是限制Cs的放电电流。O
3 overvoltage protection Introducing a Rs -Cs snubber circuit 27-2 Diode Snubber Circuit - + Df Rs Cs L Vd Io Sw snubber The roles of elements Cs的作用是限制Df上的dv/dt和关 断过电压； Rs的作用是限制Cs的放电电流