Question: In a full bridge single-phase inverter feeding RLC load
a) one thyristor and one diode conduct simultaneously
b) two thyristors conduct simultaneously
c) two thyristors or two diodes conduct simultaneously
d) four thyristors conduct simultaneously

Answer:

Introduction:
A single-phase full-bridge inverter is a type of power electronic circuit that converts DC (Direct Current) input into AC (Alternating Current) output. It utilizes four switching devices (thyristors or diodes) arranged in a bridge configuration to control the flow of current through the load. The load in this case is an RLC (Resistor-Inductor-Capacitor) load, which represents a combination of resistance, inductance, and capacitance.

Explanation:
When considering the operation of a full-bridge single-phase inverter feeding an RLC load, we need to analyze the conduction states of the switching devices (thyristors and diodes) during different parts of the AC cycle.

1. Commutation Period:
During the commutation period, the thyristors are turned off and the diodes are conducting. This ensures the current flows through the load in the desired direction. Only two diodes conduct simultaneously, providing a low resistance path for the current.

2. Positive Half-Cycle:
During the positive half-cycle of the AC output, the thyristors are triggered to conduct in a specific sequence. The sequence is as follows:
- Thyristor T1 and diode D2 conduct together
- Thyristor T2 and diode D1 conduct together

3. Negative Half-Cycle:
During the negative half-cycle of the AC output, the thyristors are triggered in a different sequence. The sequence is as follows:
- Thyristor T3 and diode D4 conduct together
- Thyristor T4 and diode D3 conduct together

Summary:
From the above analysis, it can be concluded that in a full-bridge single-phase inverter feeding an RLC load, two thyristors or two diodes conduct simultaneously during each half-cycle of the AC output. This is because the inverter operates in a bridge configuration, where the thyristors and diodes are paired in such a way that only two devices conduct at any given time, ensuring the correct polarity and direction of current flow through the load.

Therefore, the correct answer is option 'C' - two thyristors or two diodes conduct simultaneously.

Introduction:
In a full bridge single-phase inverter, the power is fed to an RLC load using four thyristors and four diodes. The thyristors and diodes are arranged in a bridge configuration and are controlled to provide an alternating current (AC) output waveform.

Explanation:
The operation of the full bridge single-phase inverter can be divided into two modes: positive half-cycle and negative half-cycle.

Positive Half-Cycle:
During the positive half-cycle of the AC input voltage, the thyristors and diodes are controlled to provide a positive half-cycle of the output voltage.

- Phase 1: The thyristor T1 is triggered and conducts, allowing current to flow through the load in the positive direction.
- Phase 2: The diode D2 is forward biased, allowing current to flow through the load in the positive direction.
- Phase 3: The diode D1 is reverse biased, blocking current flow in the negative direction.
- Phase 4: The thyristor T2 is reverse biased, blocking current flow in the negative direction.

Negative Half-Cycle:
During the negative half-cycle of the AC input voltage, the thyristors and diodes are controlled to provide a negative half-cycle of the output voltage.

- Phase 1: The thyristor T2 is triggered and conducts, allowing current to flow through the load in the negative direction.
- Phase 2: The diode D1 is forward biased, allowing current to flow through the load in the negative direction.
- Phase 3: The diode D2 is reverse biased, blocking current flow in the positive direction.
- Phase 4: The thyristor T1 is reverse biased, blocking current flow in the positive direction.

Conclusion:
From the above explanation, it can be observed that during each half-cycle of the AC input voltage, two thyristors or two diodes conduct simultaneously. This allows the full bridge single-phase inverter to provide a continuous AC output voltage to the RLC load. Therefore, the correct answer is option 'C' - two thyristors or two diodes conduct simultaneously.