Topic 3Main contentsLast lecture reviewMOSFET and IGBTTurn-on and turn-off transitions of power devicesSwitching loss and power loss of power devicesNew devices and other means for lowering loss
Main contents • Last lecture review • MOSFET and IGBT • Turn-on and turn-off transitions of power devices • Switching loss and power loss of power devices • New devices and other means for lowering loss Topic 3
1PowerDevices(1) Uncontrollable Devices (No signal for both turn-on & turn-off)K4Power Diode(2)ControllableDevices(Signalforboth turn-on&turn-off)*BJTVDMOSFIGBTGTO (IGCT)-(3)Semi-controllable Devices (Signal for turn-on, no signal for turn-off)1KThyristor,orSCRC
1 Power Devices (1) Uncontrollable Devices (No signal for both turn-on & turn-off) (2) Controllable Devices (Signal for both turn-on & turn-off) Power Diode A K C E B A G K C VDMOS IGBT G E BJT GTO (IGCT) (3)Semi-controllable Devices (Signal for turn-on, no signal for turn-off ) Thyristor, or SCR K
1.1 DiodeKAiDiDiDVratedKAC文OUD-UD00Vp(1)+UDReverse(a)blockingregionSymbol of diode(b)(c)i-vcharacteristicidealizedcharacteristic
1.1 Diode A K Symbol of diode i-v characteristic idealized characteristic
AMainparametersforapplicationVRRMa.b.IF上海三品平导体有限公司北MDC55A1600VFC.d.trr or Qm200WWchinacrRthe.公司0710-3086888-X02
A K Main parameters for application - a. VRRM b. IF c. VF d. trr or Qrr e. Rth
1.2 ThyristorAGA阳极A0三个KP1PN概层半导结NIOGP2-体门极N2K《阴极?
G 门极 K 阴极 A 阳极 P1 P2 N1 N2 四层半导体 三个PN结 K A G A 1.2 Thyristor
forward conductingIA·Blocking whenreverse biased, nomatter if there isincreasinglgate current applied=0GCIHVRSMVRRM·Conducting onlyVAK0Vbowhen forwardVORNVOSMreverseforwardbiased and there isblockingblockingtriagering current (orcalled ffiringcurrent)(触发电流）avalancheappliedtothegatebreakdown
O IA Vbo VAK VDSM VDRM VRSM VRRM forward conducting avalanche breakdown reverse blocking increasing IG forward blocking IH IG2 IG1 IG=0 •Blocking when reverse biased, no matter if there is gate current applied •Conducting only when forward biased and there is triggering current (or called firing current)(触发电流) applied to the gate
Supplementalmaterial: Holding current I (the minimum anode current to main thethyristor in the on-state)☆维持电流IH：使晶闸管维持导通所必需的最小电流。junction temperature ↑→lμ·Latching current Il (the minimum anode current required tomaintain the thyristor in the on-state immediately after a thyristorhas been turned on and thegate signal has been removed)☆擎住电流IL：晶闸管刚从断态转入通态并移除触发信号后能维持导通所需的最小电流。for the same thyristor: I,=(2~4) IH
• Holding current IH (the minimum anode current to main the thyristor in the on-state). •☆维持电流 IH ：使晶闸管维持导通所必需的最小电流。 junction temperature ↑→IH↓ •Latching current IL (the minimum anode current required to maintain the thyristor in the on-state immediately after a thyristor has been turned on and the gate signal has been removed). •☆擎住电流 IL ：晶闸管刚从断态转入通态并移除触发信号后， 能维持导通所需的最小电流。 for the same thyristor: IL≈(2~4) IH Supplemental material
Example 2: A SCR circuit is shown below. When K open,the measured output voltage value V.is incorrect. When kis closed, V.is back to normality.Why?KdRd
Example 2: A SCR circuit is shown below. When K open, the measured output voltage value Vd is incorrect. When k is closed, Vd is back to normality. Why?
1.3 MOSFETip /mADDiDipO0BUcs(th)BGG-202uGsNP沟道增强型N沟道增强型ip /mADiplDUGS(off)ooIpssBBGGUGs /V550N沟道耗尽型P沟道耗尽型10
10 N 沟道增强型 S G B D iD P沟道增强型 S G D B iD – 2 O 2 uGS /V iD /mA UGS(th) S G D B iD N 沟道耗尽型 iD S G D B P沟道耗尽型 UGS(off) I iD /mA – 5 O DSS uGS /V 5 1.3 MOSFET
1.3.1 OperatingprincipleDWhen applied positive VGs (VGs >>Vs(th), MOSFET turn-on;GWhen Vs=0 or negative, MOSFETSturn-offNchannel门?forward currentflowsfromthedrain to thesource..Note: Block only forward voltage, cannotblock negative voltage because of itsintrinsic anti-parallel diodeS
11 When applied positive VGS (VGS >> VGS(th)), MOSFET turn-on; When VGS=0 or negative, MOSFET turn-off G D S N channel 1.3.1 Operating principle •forward current flows from the drain to the source. •Note: Block only forward voltage, cannot block negative voltage because of its intrinsic anti-parallel diode