1、 *on state(static)Von-state=0 ideally Current ratings continuous,average,RMS,peak *off state(static)Ileakage=0 ideally off-state voltage ratings-forward and reverse *commutation state(dynamic)dv/dt,di/dt=ideally dv/dt rating (an equivalent capacitor in off-state,a displacement current i=C dv/dt)di/d
2、t rating (a hot point in the region where the first conduction occurs)pswitch Wstatic=Won+Woff=on-time ion(t)von-state(t)dt +off-time ileakage(t)voff(t)dt Won-major loss at lower-frequency operation Wswitch-significant at high-frequency operation Wswitch=turn-on i(t)v(t)dt +turn-off i(t)v(t)dt Paver
3、age=(Wstatic+Wswitch)/TPower Devices *permits current flow in one direction only *can withstand a forward voltage(except diodes)*can be turned on or off by a relatively small controlling current or voltage(Diode,SCR,GTO,BJT,MOSFET,IGBT,IPM)characteristics,rather than the physics firing requirements
4、ratingscomparisons of the devicesPower DevicesPower DevicesStructure and symbolCharacteristicsPower Devicesreverse recovery time trrTypical turn-off condition of a diode.Fast Recovery Diode trr(SCR)Power DevicesStructure and symbolCharacteristics with no gate current AnodeCathodeCharacteristics with
5、 gate current+AnodeIaIcIgIb1Ib2 Gate-CathodePNNPIgIb1 Ia,Ic Ib2 Positive feedback a.Gate-cathode poor P-N junction within a given production batchIgmin Ig Igmax Vgmin Vg Vgmax IgVg 0 at all times.Special types of wires to reduce internal self-inductance.Circuit model for a battery on charge.Inductio
6、n motor circuit model.provides a defined v(t)value at any current.It displays zero impedance to current flow.maintains a defined i(t)value at any voltage.It displays infinite impedance to external voltage.Ideal and real voltage sources comparedSeries inductance of a real voltage source exhibits curr
7、ent source behavior on short time scale.DC source interfaces(Lext or Cext for enhancing current or voltage behavior)CextAC source interfaces series or parallel LC pair for enhancing current or voltage behavior(Lext/Cext)sLs,(L/C)sLs Study on your own with reference to Chapter 11 and 12 of the textbook,“Elements of Power Electronics”by Philip T.Krein.Submit a paper to me in two weeks describing your understanding.You will get a bonus up to 5 points.
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