‫بسم هللا الرحمن الرحيم‬
The Islamic University of Gaza
Faculty of Engineering
Electrical Engineering Department
POWER ELECTRONICS
EELE 5450 — Summer 2012
Instructor: Eng. Jalal Al Roumy
Lecture 21
HALF-CONTROLLED BRIDGE WITH RESONANT
LOAD
If the resonance is to continue for most of the half-cycle in order to
reduce the current harmonic content, the value of 1/a = t, the time
constant, must be a significant part of the half-cycle period.
HALF-CONTROLLED BRIDGE WITH RESONANT
LOAD
Example
HALF-CONTROLLED BRIDGE WITH RESONANT
LOAD
Example
THREE-PHASE BRIDGE INVERTERS
A full-bridge three-phase BJT inverter is shown. The load is a balanced star
connection of pure resistors. If the load was inductive, feedback diodes would be
connected across each switch; these could be built into the switch module. In this
type of inverter, two or three switches could be conducting simultaneously.
Two switches conducting
The conducting sequence is as follows (each device
conducts for a 120o period):
Two conducting devices- line voltage and current
Values of line voltage and line (also phase) current for 60o intervals
are shown, from which the waveforms are constructed. The other
two lines have identical values, displaced mutually by 120o
Two conducting devices- line voltage and current
Values of line voltage and line (also phase) current for 60o intervals
are shown, from which the waveforms are constructed. The other
two lines have identical values, displaced mutually by 120o
Two conducting devices- line voltage and current
Two conducting devices- line voltage and current
Three switches conducting
The conducting sequence is as follows (each device
conducts for a 180o period):
Three conducting devices- line voltage and current
Values of line voltage and line (also phase) current for 60o intervals
are shown, from which the waveforms are constructed. The other
two lines have identical values, displaced mutually by 120o
Three conducting devices- line voltage and current
Values of line voltage and line (also phase) current for 60o intervals
are shown, from which the waveforms are constructed. The other
two lines have identical values, displaced mutually by 120o
Comparing rms line currents
Comparing rms line currents
End of Lecture