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Three Phase DC-AC Converters with 120 degree conduction mode
Figure: 5.25 Circuit diagram of three phase bridge inverter
120° mode of conduction
In this mode of conduction, each electronic device is in a conduction state for 120°. It is most suitable
for a delta connection in a load because it results in a six-step type of waveform across any of its phases.
Therefore, at any instant only two devices are conducting because each device conducts at only 120°.
The terminal A on the load is connected to the positive end while the terminal
B is connected to the
negative end of the source. The terminal C on the load is in a condition called floating state.
Furthermore, the phase voltages are equal to the load voltages as shown below.
Phase voltages =
Line voltages
V
AB
= V
V
BC
= −V/2
V
CA
= −V/2