17-08-2012, 04:32 PM
Power Electronics
[attachment=31917]
Generic Switch Symbol
Idealized switch symbol
When on, current can flow only in the direction of the arrow
Instantaneous switching from one state to the other
Zero voltage drop in on-state
Infinite voltage and current handling capabilities
Desirable Switch Characteristics
Idealized switch symbol
When on, current can flow only in the direction of the arrow
Instantaneous switching from one state to the other
Zero voltage drop in on-state
Infinite voltage and current handling capabilities
> No need for cascading multiple devices
Short turn-on and turn-off times
> High switching speeds
Small control power required to switch the device
> Simplify control circuit design
Large dv/dt and di/dt ratings
>Minimize the need for external or snubber circuits
Thyristors
The thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current pulse, and continue to conduct for as long as they are forward biased
[attachment=31917]
Generic Switch Symbol
Idealized switch symbol
When on, current can flow only in the direction of the arrow
Instantaneous switching from one state to the other
Zero voltage drop in on-state
Infinite voltage and current handling capabilities
Desirable Switch Characteristics
Idealized switch symbol
When on, current can flow only in the direction of the arrow
Instantaneous switching from one state to the other
Zero voltage drop in on-state
Infinite voltage and current handling capabilities
> No need for cascading multiple devices
Short turn-on and turn-off times
> High switching speeds
Small control power required to switch the device
> Simplify control circuit design
Large dv/dt and di/dt ratings
>Minimize the need for external or snubber circuits
Thyristors
The thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current pulse, and continue to conduct for as long as they are forward biased