Thyristor Operation in Inverters Quiz

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In the 180° conduction mode, what triggers the thyristors to create the desired output voltages?

Gating signals applied at intervals of 30°

Gating signals applied at intervals of 60° (correct)

Gating signals applied in pairs at random times

Gating signals applied at intervals of 120°

Which of the following accurately describes the operation of thyristor pairs in the 180° conduction mode?

Each pair of thyristors conducts simultaneously for 180°

Each pair conducts for 90° intervals

Thyristors conduct in a random sequence

Thyristors alternate conduction in 180° intervals (correct)

What is the primary function of a three-phase inverter?

To convert three-phase AC to single-phase AC

To convert DC into three-phase AC output (correct)

To synchronize the phase angles across multiple inverters

To regulate the voltage of a DC source

During the 120° conduction mode, how many devices are conducting at any given instant?

Three devices are actively conducting Signup and view all the answers

What relationship exists between the phase voltages and the line voltages in the 180° conduction mode?

Phase voltages are directly subtracted to yield line voltages Signup and view all the answers

What type of circuit uses both inductance and capacitance to ensure efficient commutation?

LC Resonant Circuit Signup and view all the answers

Which method utilizes an external voltage source to force turn-off of a semiconductor device?

Voltage Commutation Signup and view all the answers

What is the primary function of the parallel capacitor in the Parallel Capacitor Commutation method?

To provide a low-impedance path for current diversion Signup and view all the answers

In which type of forced commutation does an external circuit divert current away from the device?

Current Commutation Signup and view all the answers

Which type of commutation involves applying a pulse to the gate of a semiconductor device?

Gate Pulse Commutation Signup and view all the answers

What is a key characteristic of Voltage Commutation with Transformer?

It utilizes a transformer to provide a higher voltage for faster turn-off. Signup and view all the answers

Which of the following correctly describes Auxiliary Commutation?

It uses additional circuits to assist the commutation process. Signup and view all the answers

What occurs when thyristor T1 is triggered again in Mode-III of the parallel inverter operation?

Thyristor T2 becomes reverse biased. Signup and view all the answers

Which statement accurately describes the output voltage waveform of a parallel inverter?

It is approximately rectangular. Signup and view all the answers

What is a major disadvantage of a parallel inverter when operating under low-frequency conditions?

It leads to transformer core saturation. Signup and view all the answers

In a single-phase PWM inverter, what is the resulting voltage generated by the half-bridge inverter?

Bipolar voltage of -200V or +200V. Signup and view all the answers

How does the magnitude of the fundamental component of a full-bridge inverter's output compare to that of a half-bridge inverter?

It is twice the value of the half-bridge inverter. Signup and view all the answers

What is a key characteristic of the harmonic content produced by a full-bridge inverter?

Harmonics appear at twice the carrier frequency. Signup and view all the answers

What is the function of extra feedback diodes in a parallel inverter circuit?

To remove energy trapped by the commutating capacitor. Signup and view all the answers

In the context of a three-phase bridge inverter, what defines a 'step'?

A change in the firing from one thyristor to another. Signup and view all the answers

What type of applications are parallel inverters typically used for?

High current, low voltage applications. Signup and view all the answers

Which of the following best describes the lagging behavior observed in inductive loads supplied by a parallel inverter?

Current lags voltage. Signup and view all the answers

What is the fundamental condition for an RLC circuit to be classified as underdamped in a series inverter?

R < (4L/C) Signup and view all the answers

In the operation of a series inverter, what happens to the capacitor voltage after thyristor T1 is triggered?

The voltage increases and exceeds the supply voltage Vdc. Signup and view all the answers

Which mode of operation in a series inverter has both thyristors T1 and T2 in the OFF state?

Mode II Signup and view all the answers

What are series inverters also referred to due to their commutation method?

Self-commutated inverters Signup and view all the answers

What is a major disadvantage of series inverters regarding the waveform of the load voltage?

The output voltage waveform experiences distortions and harmonic content. Signup and view all the answers

Why is the maximum operating frequency of a series inverter limited?

To avoid short-circuiting the DC input source. Signup and view all the answers

What role does the capacitor play in the operation of a series inverter?

It stores charge and influences the load current direction. Signup and view all the answers

What is the expected output frequency range of a series inverter?

200 Hz to 100 kHz Signup and view all the answers

What issue arises due to the discontinuous current flow in a series inverter?

High peak current requirements Signup and view all the answers

What is the primary function of the thyristor T2 in the modified series inverter circuit?

To maintain reverse bias of T2 while T1 is conducting. Signup and view all the answers

Which characteristic of the modified series inverter allows for an increase in output frequency?

The overlapping conduction period of the thyristors. Signup and view all the answers

In the operation of the improved series inverter, what happens at the end of one half cycle when the load current becomes zero?

Both C1 and C2 experience a change in voltage polarity. Signup and view all the answers

What is a major drawback of the basic series inverter circuit?

It creates high harmonic content in the output current. Signup and view all the answers

What type of output voltage does a parallel inverter produce?

Squarer wave output from DC power input. Signup and view all the answers

How does the thyristor commutation process occur in a parallel inverter?

A natural commutation from the load current leads to turning OFF. Signup and view all the answers

Which configuration is more desirable for practical applications of inverters?

Parallel inverter because the load voltage is load-independent. Signup and view all the answers

What is a significant advantage of using a modified series inverter?

Simplified commutation circuit. Signup and view all the answers

What action takes place during mode-I operation of the parallel inverter?

Thyristor T1 is triggered, causing voltage across the primary to double. Signup and view all the answers

What is the result of applying reverse voltage across T1 during commutation in a parallel inverter?

T1 will be forced to turn off due to reverse bias. Signup and view all the answers