Power Electronic Circuits

Selected Properties of the Ideal Switch

1. Controllable: able to turn ON or OFF at will.

We prefer voltage control over current control (see #6)

2. Voltage blocking: blocks large voltages when OFF. Forward AND Reverse.

3. Current conduction: Conduct large currents when ON. Forward AND Reverse.

4. Fast Speed: Switch from ON to OFF or back quickly (instantly preferred). See #9)

5. Negligible losses: conduction losses and switching losses are negligible

6. Power for control source is negligible. Voltage control does this far better than current control.

7. Negligible deviation from true ON or OFF behavior

a. Leakage current in the OFF state is negligible

b. Forward voltage in the ON state is negligible

 8. Positive temperature coefficient (Resistance rises the temperature rise). This situation tends to contribute to circuit stability.

9. Large di/dt and dv/dt ratings. Helps speed!