1. Identify different important features and steady-state and switching characteristics of power semiconductor diodes
  2. Understand the importance of forward and reverse recovery times
  3. Know the applications of different power semiconductor diodes in Power Electronic Circuits
  4. Get idea on characteristics of a commercial diode
    Power Diode: Features
    Power diodes have larger power-, voltage-, and current handling capabilities than that of ordinary signal diodes.
    Power diodes have an additional lightly doped drift region (n-) which helps to increase the voltage capability of the device.
    However, the frequency response or switching speed is low compared to that of signal diodes.POWER SEMICONDUCTOR DIODES
    Applications: 1) as uncontrolled rectifiers to convert AC to fixed DC voltages and 2) as freewheeling diodes to provide a path for the current flow in inductive loads.
    Power Diode: circuit symbol and device structure
    I-V Characteristics (at steady state) of Power Diode
    I-V Characteristics (at steady state) of Power Diode
    Forward-biased region, where vD > 0. ID is very small if vD < VTH (threshold or cut-in or turn-on or knee voltage). ID is large if vD >VTH. The diode conducts fully and ID is limited externally.
    Reverse-biased region, where vD < 0. The reverse leakage current, IR (or IS) is very small, in the range of micro- to milli-ampere due to the flow of the thermally generated carriers.
    Breakdown region, where vD < -VBR (breakdown voltage). VBR is avalanche or zener voltage, where avalanche breakdown begins to occur. The reverse current increases rapidly with a small change in reverse voltage beyond VBR. If the current is limited external, the diode is not spoiled as long as the power dissipation (ID*VBR) < PD,max.
    Comparisons of Power and Signal Diodes
    Power diodes: ~1V
    Signal diodes: ~0.7V
    Forward i-v Characteristics
    Power diodes: linear
    Signal diodes: exponential
    Ron (ohmic resistance)
    Power diodes: >0Ω
    Signal diodes: ~0Ω
    previous Control Characteristics Devices
    next Switching Characteristics of Power Diodes
    Share this article :


    Post a Comment

    Please wait for approval of your comment .......