In this tutorial, we are going to learn about the Best Topics of Power Electronics.
- These are uncontrolled rectifying devices. It has two states which are ON and OFF states are controlled by power supply.
- Power Diode is a two layer, two terminal P-N semiconductor devices.
- The two terminals of diodes are anode and cathode.
Types of Power Diode
General Purpose Diodes
- These diodes have relatively high reverse recovery time, of the order of about 25µS.
- Their current ratings vary from 1A to several thousand amperes and the range of voltage rating is from 50V to 5KV.
Fast Recovery Diodes
- The diodes with low reverse recovery time, of about 5µS or less.
- Their current ratings vary from 1A to several thousand amperes and the range of voltage rating is from 50V to 3KV.
- This class of diodes uses metal to semi conductor junction for rectification purpose instead of PN junction.
- Their reverse voltage ratings are limited to about 100V and forward current rating vary from 1A to 300A.
- It has four layer three junction like PNPN semiconductor switching device.
- It has 3 terminals these are anode (A), Cathode (K) and gate (G).
- It is a unidirectional device.
SCR – Silicon Controlled Rectifier
- It has a four layer solid state current controlling device. It is invented by Gordon Hall Fran W. There is below are the image of SCR electronic symbol.
- It is called as controlled rectifier because this device requires a gate signal to turn it ON and it can also used as rectifying diode.
Below are the characteristics:
As per the below image can see there is three modes of operation:
- Reverse Blocking Mode
- Forward Blocking Mode (Off State)
- Forward Conduction Mode (On State)
Below are the main point of SCR
It is the minimum anode current required to maintain the Thyristor in the ON state immediately after a Thyristor has been turned ON state has occurred and the gate signal has been removed.
Latching Current (Ih)
Latching current is the minimum anode current to maintain the thyristor in the ON state.
Below is the point for turn on methods for SCR:
- Forward voltage triggering
- Gate triggering
- Dv/Dt triggering
- Temperature triggering
- Light triggering