The semiconductor
devices which are used for inverter circuit is given below. The SCR is used for
high power rating inverter.
- Earlier the BJT is used as semiconductor device in the inverter circuit.
- The BJT requires continuous base current in order to keep it on.
- When the base current becomes zero, the BJT turns off.
Metal Oxide Field Effect Transistor ( MOSFET )
- The base current in the BJT controls the output voltage therefore it is called as current control device whereas the gate – source voltage control the output current in the MOSFET therefore it is called as voltage control device.
- When the gate – source voltage exceeds the threshold voltage, the MOSFET turns on.
- When the gate – source voltage below threshold voltage, the MOSFET turns off.
- As the MOSFET is voltage controlled device, it requires low power but it consumer high power due to high gate – source resistance.
- The capacity of MOSFET based inverter is in kW and less than 700 voltage.
- The IGBT has combined characteristics of MOSFET and BJT.
- The input impedance of the IGBT is high. The switching and conduction losses in the BJT are very low.
- The IGBT is a voltage controlled device similar to MOSFET.
- The IGBT is used as semiconductor device when high output voltage and current requires.
- Once the SCR is switched on in the DC circuit, it requires commutation circuit to turn it off.
- The GTO is a semiconductor device which is turned off by negative pulse.
- The main disadvantage of the GTO is that it has higher voltage drop when it is in turned on condition.
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