Session1semiconductors

  • 1,550 views
Uploaded on

 

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads

Views

Total Views
1,550
On Slideshare
0
From Embeds
0
Number of Embeds
1

Actions

Shares
Downloads
7
Comments
0
Likes
0

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. UEENEEG008B Part AElectronic power and control 1
  • 2. TextbooksElectrical Trade Principles Jeffery Hampson and Steven Hanssen Revision 01 2
  • 3. This is an introductory module only and it leadsonto other electronic and power control studies Principle of operation of common semi-conductor devices Single and 3 phase rectifiers, (½ and full wave) Filters and Voltage Regulators Operating principles, and safety of inverters Principles and operation of common transducers Principles and operation of programmable relays Revision 01 3
  • 4. Semiconductors • Silicon is bonded or doped with another element• When the silicon has one less electron in the bond it is called a P Type material • When the silicon has more electron in the bond it is called a N Type material Revision 01 4
  • 5. Rectifier Diodes• The P-N Junction• Diodes….• In simple terms, diodes allow current to flow in 1 direction only. Revision 01 5
  • 6. The p-n JunctionWhen p-type material and n-type material are fused together, a p-n junction is formed. Some free electrons move across the junction to occupy some of the holes and an area depleted of current carriers is created. p-type n-type -- + + -- + + -- + + Depletion Layer Revision 01 6
  • 7. Barrier potential p-type n-type -- + + -- + + -- + + Barrier Potential Electrons move from the n type material to the p type material and fill available holes. The loss of electrons from the n-type material results in a +ve charge The gained electrons in the p-type material results in a -ve charge These charged areas form the BARRIER POTENTIAL These charges form a BARRIER POTENTIAL of about 0.7 volts for Silicon and 0.3 volts for Germanium 7
  • 8. Forward bias P type N type - -- + + + - - + + - -- + + + holes electrons +ve potential connected to p-type –ve potential connected to n-type At the same time, electrons flow from the (-ve) terminal of the supply through the n-type material into the depletion region. The effect is the cancelling of the barrier potential. Therefore, the p-n junction will conduct in this direction. Current will flow in the direction shown. Electrons are attracted from the depletion region, and flow through the p-type material to the (+ve) terminal of the supply. Revision 01 8
  • 9. Reverse bias P type N type - -- + + + - -- + + + - -- + + + electrons electrons• + ve potential connected to n-type – ve potential connected to p- type• A few electrons moving from the (-) terminal flowing through the p type material. A few electrons will also flow from the n-type material to the (+) terminal.• The effect is a large increase in the barrier potential.• Therefore, the diode WILL NOT CONDUCT in this direction. Revision 01 9
  • 10. Diode characteristic curves IF Reverse Bias mA Silicon Diode 200V 100 0 V 0.6 1.0 V VRBreakdown IR Forward Voltage VFVoltage VBR Germaniu m Diode µA Diode US Forward Bias Revision 01 10
  • 11. Diode specifications• Forward Voltage VF -The value of the voltage drop across a forward bias diode.• Average Forward Current IF - The average current of a forward bias diode.• IF(max) -Maximum average forward current. (Heat sink)• Surge Current IS - maximum forward surge current, not exceeding one cycle• Peak Reverse Voltage PRV or Peak Inverse Voltage PIV (same) The maximum reverse voltage that can be applied to a diode. The diode will break down if this value is exceeded. Revision 01 11
  • 12. p-n junction diodes The leads of a diode, form a heat sink. If these Diode marking leads are cut shorter the indicates current rating of the Cathode diode must be reduced. The epoxy casing is forA semiconductor strength and works as a heat sink.device that has one p-njunction is the p-njunction diode. Standard symbol Anode (A)Commonnon-standardsymbols Cathode (K) Revision 01 12
  • 13. Diode testing with analogue multimeter Ohmmeter Ohmmeter M 0 I I