ELCT 704 Power Electronics Assignment 1

Faculty of Information Engineering & Technology 
Electrical & Electronics Department 
Power Electronics (ELCT 704)
German University in Cairo

A 220V, 50Hz voltage source is used to supply the armature circuit of an R-L-E load through a single phase half wave controlled rectifier. If the value of the resistance is 1Ω, the inductance is 0.015H and the battery voltage is 20V.

• Find an expression for the instantaneous output current in terms of the firing angle α and the extinction angle β. (No calculations are required)
• Find the firing angle at which the average output voltage becomes maximum.
• For the firing angle of Part (2), find the average output voltage and average current.
• For a firing angle of 90^o, sketch the following:
  1. The supply voltage and the battery voltage on the same graph
  2. The output voltage
  3. The output current
  4. The voltage across the thyristor