Question

In a parallel inverter

• A. Each thyristor is turned on twice during each cycle
• B. Each thyristor is turned on once during each cycle
• C. Each thyristor is turned on either once or twice during each cycle
• D. Each thyristor may be turned on up to four times during each cycle

Hint:

Parallel inverter uses alternate conduction of SCRs.

Answer 1

The Correct Option is A

Step 1: Describe the parallel inverter circuit.
In a parallel inverter, two thyristors (T1 and T2) share a common commutating capacitor. The capacitor is pre-charged by the currently conducting thyristor and then used to force-commutate (turn off) that thyristor when the next one is triggered.

Step 2: Count the trigger events per thyristor per cycle.
For one complete output AC cycle: T1 is triggered once to produce the positive half cycle, then the commutation capacitor triggers T1 again during the negative half cycle transition. Each thyristor is fired twice during one complete cycle.

Step 3: State the conclusion.
Due to forced commutation in a parallel inverter, each thyristor is turned on twice per output cycle. \[ \boxed{\text{Each thyristor is turned on twice during each cycle}} \]