Chopper Circuits and Control Strategies Quiz

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What does the duty cycle 'K' represent in time ratio control?

The maximum voltage level achievable
The total time period of the operation
The output voltage of the system
The ratio of ON time to the period (correct)

Which control strategy varies the ON time while keeping frequency constant?

Constant frequency operation (correct)
Variable frequency operation
Voltage commutation control
Current limit control

What occurs during frequency modulation control?

The ON time is kept constant
The time period 'T' remains unchanged
Current values are limited to preset levels
The frequency is altered to adjust voltage (correct)

What is a disadvantage of variable frequency operation?

Potential interference with telephone lines (A) Signup and view all the answers

How does the current limit control strategy maintain constant current?

By turning the DC-DC converter ON and OFF (C) Signup and view all the answers

What does a voltage-commutated chopper primarily utilize for thyristor commutation?

Application of a large reverse voltage (B) Signup and view all the answers

Which component is NOT part of the voltage-commutated chopper circuit?

Transistor (C) Signup and view all the answers

What must occur for the operation of a voltage-commutated chopper?

The capacitor must be charged with correct polarity (A) Signup and view all the answers

What is the goal of current limit control in a DC-DC converter?

To maintain current between upper and lower limits (D) Signup and view all the answers

Which term describes the process of turning off a conducting thyristor?

Commutation (A) Signup and view all the answers

What is the primary function of chopper circuits?

To convert fixed dc voltage into adjustable dc voltage (D) Signup and view all the answers

Which of the following describes an AC Link Chopper?

It requires a transformer to perform the conversion (D) Signup and view all the answers

Why are chopper circuits necessary?

To enable the use of fixed dc voltage in variable applications (B) Signup and view all the answers

What makes DC Choppers more efficient than AC Link Choppers?

They perform a single-stage conversion (C) Signup and view all the answers

Which of the following control strategies is NOT employed in DC choppers?

Voltage Feedback Control (C) Signup and view all the answers

Chopper circuits can be considered as:

Static power electronic devices that behave like transformers (D) Signup and view all the answers

What happens to the output voltage in a DC chopper?

It can vary based on control methods used (B) Signup and view all the answers

What are the disadvantages of AC Link Choppers?

High cost and lower efficiency (A) Signup and view all the answers

Which of the following is true regarding the need for DC to DC conversion?

It is crucial for devices that require adjustable dc input (D) Signup and view all the answers

What type of input does a chopper circuit primarily work with?

Fixed dc voltage (B) Signup and view all the answers

What happens to the charging current once the thyristor TM is triggered in the voltage commutated chopper circuit?

It decays to zero. (B) Signup and view all the answers

How does the load voltage change when the capacitor discharges through the load in a voltage commutated chopper?

It decreases from 2 Vdc to Vdc. (D) Signup and view all the answers

What is the role of the diode D in the voltage commutated chopper circuit?

To keep the voltage across the capacitor constant. (D) Signup and view all the answers

What occurs when the auxiliary thyristor TA is triggered in the system?

Thyristor TM is turned off. (A) Signup and view all the answers

Which chopper type is designed to increase the output voltage?

Step-up chopper (B) Signup and view all the answers

When the voltage across the capacitor becomes zero, which condition exists in the voltage commutated chopper?

No current flows through the load. (D) Signup and view all the answers

What does a step-down chopper primarily achieve in a circuit?

Reducing the output voltage. (C) Signup and view all the answers

Which of the following is true about the operation of an AC chopper?

It adjusts the firing angle of thyristors. (C) Signup and view all the answers

What defines the behavior of a voltage commutated chopper when the capacitor begins to charge again?

It charges with reverse polarity of the supply input. (C) Signup and view all the answers

In what scenario is the Jones chopper mentioned?

When discussing unique applications or devices. (A) Signup and view all the answers

What occurs after the thyristor TM is triggered in the voltage commutated chopper?

The supply input is across the load (A) Signup and view all the answers

How does the load voltage behave when the capacitor is discharged through the load?

It changes from 2 Vdc back to Vdc (B) Signup and view all the answers

What is the role of the auxiliary thyristor TA during the operation of the voltage commutated chopper?

It causes TM to become reverse biased (B) Signup and view all the answers

What does the diode D do when the voltage across the capacitor is reversed?

It maintains the voltage –Vs constant (B) Signup and view all the answers

What happens to the charging current when the capacitor voltage is equal to the supply input voltage?

The charging current decreases to zero (C) Signup and view all the answers

When does the process of reverse charging begin in the voltage commutated chopper?

At the instant t1 (C) Signup and view all the answers

What is the impact of overcharging the capacitor in the chopper circuit?

The FD gets forward biased (A) Signup and view all the answers

Which component is essential to maintain the oscillatory circuit in the voltage commutated chopper?

Inductor (A), Capacitor (B) Signup and view all the answers

What defines a step-up chopper in comparison to other types?

It increases the average output voltage (A) Signup and view all the answers

What regulates the power flow within an AC chopper?

Modifying the firing angle of thyristors (D) Signup and view all the answers

What is the primary characteristic of variable frequency operation in time ratio control?

Both frequency and time period are changed. (D) Signup and view all the answers

What is a notable disadvantage of the frequency modulation (FM) method in control strategy?

It may intrude with telephone lines and signaling. (D) Signup and view all the answers

How does the current limit control strategy operate during a DC to DC conversion?

It turns the converter ON and OFF to limit current within preset bounds. (D) Signup and view all the answers

What type of thyristor commutation does a voltage-commutated chopper use?

Reverse voltage application. (B) Signup and view all the answers

What is a necessary condition for the operation of a voltage-commutated chopper?

The capacitor must be charged to supply input with the same polarity. (D) Signup and view all the answers

In what scenario does the current freewheel through the diode during current limit control?

During the exponential fall of current in the OFF state. (B) Signup and view all the answers

Which control strategy is typically preferred for choppers or DC-DC converters?

Constant frequency with pulse width modulation. (A) Signup and view all the answers

What is the main function of extra elements in forced commutation?

To turn off the thyristor under specific conditions. (C) Signup and view all the answers

What defines the behavior of a thyristor in a high power circuit when using a voltage-commutated chopper?

It relies on a large reverse voltage for commutation. (D) Signup and view all the answers

What is the primary purpose of a chopper circuit in electricity conversion?

To adjust fixed DC voltage into variable DC voltage. (C) Signup and view all the answers

What is a primary reason for the need for chopper circuits?

To provide adjusted DC power from fixed voltage sources. (A) Signup and view all the answers

What distinguishes the DC chopper from the AC link chopper?

The DC chopper converts DC to DC in a single stage. (B) Signup and view all the answers

Which of the following statements is true regarding time ratio control in DC choppers?

It varies the average output voltage by changing the ON-time duration. (B) Signup and view all the answers

What is a characteristic of the AC link chopper process?

It includes both transformation and rectification stages. (A) Signup and view all the answers

Which of the following is NOT a control strategy used in DC choppers?

Voltage modulation control (A) Signup and view all the answers

What aspect of a chopper circuit allows it to behave like an AC transformer?

Its ability to convert fixed DC to variable DC. (D) Signup and view all the answers

What can be said about the efficiency of AC link choppers compared to DC choppers?

DC choppers are generally more efficient. (A) Signup and view all the answers

What is the main action occurring during current limit control in a DC chopper?

Limiting the average output current to a specified value. (B) Signup and view all the answers

What is a drawback of using AC link choppers?

They typically require a higher number of components. (C) Signup and view all the answers

What defines the behavior of a DC chopper in terms of its output voltage?

It adjusts its output voltage by varying the duty cycle. (B) Signup and view all the answers

Chopper Circuit

A circuit that converts a fixed DC voltage into an adjustable DC voltage.

DC to DC Converter

Another name for a chopper circuit.

AC Link Chopper

A two-stage DC-to-DC converter that first converts DC to AC, then AC back to DC using a transformer.