1. CONTROLLABLE SWITCHES
Overview
Power Electronics MSc

2. 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
Power Electronics MSc

3. Switching Characteristics (linearized)
Switching Power Loss is proportional to:
switching frequency
turn-on and turn-off times
Power Electronics MSc

4. Bipolar Junction Transistors (BJT)
Used commonly in the past
Now used in specific applications
Replaced by MOSFETs and IGBTs
Power Electronics MSc

5. Various Configurations of BJTs
Power Electronics MSc

6. MOSFETs Easy to control by the gate
Optimal for low-voltage operation at high switching frequencies
On-state resistance a concern at higher voltage ratings
Power Electronics MSc

7. Gate-Turn-Off Thyristors (GTO)
Slow switching speeds
Used at very high power levels
Require elaborate gate control circuitry
Power Electronics MSc

8. GTO Turn-Off Needs a turn-off snubber 2011.10.06.
Power Electronics MSc

9. IGBT
Power Electronics MSc

10. Mos Controlled Thyristor (MCT)
Power Electronics MSc

11. Comparison of Controllable Switches
Power Electronics MSc

12. Summary of Device Capabilities
Power Electronics MSc