EEE UNIT 3 E VEHICLE 2 MARKS

 

Here are 5 two-mark questions from Unit III – Electronics and Sensor-less Control in EV, designed using Apply, Analyze, Evaluate, and Create levels of Bloom's Taxonomy, along with model answers:

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✅ 1. Apply Level

Q: Apply your understanding of power semiconductor devices to recommend whether an IGBT or a MOSFET is more suitable for high-voltage inverter applications in EVs. Justify your answer.
Answer:
IGBT is more suitable for high-voltage applications because it can handle higher voltage and current with lower conduction losses compared to MOSFETs, making it ideal for inverter circuits in EVs.

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✅ 2. Analyze Level

Q: Analyze the safety challenges involved in handling high-voltage components in electric vehicles.
Answer:
High-voltage EV systems can cause severe electric shock, fire hazards, and component damage. Proper insulation, automatic disconnection systems, and protective equipment are essential to ensure user and technician safety.

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✅ 3. Evaluate Level

Q: Evaluate the effectiveness of sensor-less control techniques in autonomous electric vehicles compared to traditional sensor-based methods.
Answer:
Sensor-less control reduces system cost and improves reliability by eliminating physical sensors. However, it may have limitations under low-speed conditions or rapid dynamic changes where sensor feedback could be more accurate.

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✅ 4. Analyze Level

Q: Analyze how the phase inductance-based method contributes to rotor position estimation in sensor-less motor control.
Answer:
In the phase inductance-based method, the inductance varies with rotor position. By measuring this variation, the system can estimate rotor location without physical sensors, enabling sensor-less motor operation.

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✅ 5. Create Level

Q: Create a simple model to demonstrate how observer-based control can be implemented for estimating speed in a BLDC motor.
Answer:
An observer-based model uses real-time voltage and current inputs along with motor parameters to estimate rotor speed and position. Kalman Filter or Luenberger Observer can be implemented in the controller software to simulate this.

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EEE MACHINES 1 UNIT 3 MCQ QUESTIONS AND ANSWERS

 Here are 20 MCQs based on UNIT III: SINGLE PHASE TRANSFORMERS, focused on Understand and Apply levels of Bloom’s Taxonomy.

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⚡ UNIT III – SINGLE PHASE TRANSFORMERS

MCQs Based on Understand & Apply Levels

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🔷 Section A: Transformer Basics & EMF Equation

1. Which of the following is the basic working principle of a transformer?

A) Electrostatic induction

B) Magnetic repulsion

C) Electromagnetic induction

D) Thermionic emission

Answer: C) Electromagnetic induction

2. The EMF equation of a transformer is given by:

A) E = B × L × v

B) E = 4.44 × f × N × Φ

C) E = I × R

D) E = N × V

Answer: B) E = 4.44 × f × N × Φ

3. If a transformer has a turns ratio of 1:2, then the transformer is:

A) Step-up transformer

B) Step-down transformer

C) Isolation transformer

D) Auto transformer

Answer: A) Step-up transformer

4. Transformer ratings are usually expressed in:

A) kW

B) Amps

C) kVA

D) HP

Answer: C) kVA

5. Which of the following applications requires a step-down transformer?

A) Transmission lines

B) Power stations

C) Home appliances

D) Solar power plants

Answer: C) Home appliances

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🔷 Section B: Phasor Diagrams & Ideal Transformer

6. In an ideal transformer, which of the following is zero?

A) Core flux

B) Copper loss

C) Induced EMF

D) Magnetizing current

Answer: B) Copper loss

7. In a no-load phasor diagram, the no-load current lags the applied voltage by:

A) 0°

B) 90°

C) 180°

D) Nearly 90°

Answer: D) Nearly 90°

8. At lagging power factor load, the load current in the phasor diagram will:

A) Lead the voltage

B) Lag the voltage

C) Be in phase

D) None of these

Answer: B) Lag the voltage

9. The equivalent circuit of a transformer helps to determine:

A) Cooling rate

B) Core shape

C) Voltage regulation and efficiency

D) Flux leakage

Answer: C) Voltage regulation and efficiency

10. Which element of equivalent circuit represents the iron losses?

A) Series resistance

B) Leakage reactance

C) Parallel resistance

D) Magnetizing reactance

Answer: C) Parallel resistance

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🔷 Section C: Voltage Regulation & Efficiency

11. Voltage regulation of a transformer is defined as:

A) Ratio of primary to secondary voltage

B) Change in secondary voltage from no-load to full-load

C) Change in current from full-load to no-load

D) Power factor variation

Answer: B) Change in secondary voltage from no-load to full-load

12. A transformer is said to be more efficient when:

A) Core loss > Copper loss

B) Copper loss > Core loss

C) Core loss = Copper loss

D) Losses are not minimized

Answer: C) Core loss = Copper loss

13. What is all-day efficiency concerned with?

A) Peak load performance

B) Constant load performance

C) Energy consumed over a 24-hour period

D) Cooling capacity

Answer: C) Energy consumed over a 24-hour period

14. If a transformer has full-load efficiency of 98%, the losses are:

A) 2% of output

B) 2% of input

C) 2% of kVA

D) 2% of voltage

Answer: B) 2% of input

15. To find condition for maximum efficiency, we equate:

A) Voltage and current

B) Core loss and copper loss

C) Primary and secondary voltage

D) Iron loss and load power

Answer: B) Core loss and copper loss

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🔷 Section D: Parallel Operation & Auto Transformer

16. For parallel operation, the transformers must have:

A) Equal weight

B) Same polarity and voltage ratio

C) Same size

D) Different impedance

Answer: B) Same polarity and voltage ratio

17. One major advantage of parallel operation is:

A) More noise

B) Load sharing

C) Higher losses

D) Increased copper usage

Answer: B) Load sharing

18. An auto transformer differs from a two-winding transformer by having:

A) No magnetic core

B) One winding common to both primary and secondary

C) Two isolated windings

D) No current transformation

Answer: B) One winding common to both primary and secondary

19. Which of the following is a disadvantage of an auto transformer?

A) More weight

B) More copper

C) Lack of electrical isolation

D) Less efficiency

Answer: C) Lack of electrical isolation

20. Which type of transformer is more efficient for the same rating?

A) T

wo-winding transformer

B) Auto transformer

C) Isolation transformer

D) Pulse transformer

Answer: B) Auto transformer

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EEE E VEHICLE UNIT 3 20 MCQ QUESTIONS

 Here are 20 MCQs based on Unit III: Electronics and Sensor-less Control in EV, focusing on Understand and Apply levels of Bloom’s taxonomy:

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⚡ ELECTRONICS AND SENSOR-LESS CONTROL IN EV – MCQs

Section A: Basic Electronics Devices & Power Converters (Understand & Apply)

1. Which of the following devices allows current to flow in only one direction?

A) BJT

B) Thyristor

C) Diode

D) IGBT

Answer: C) Diode

2. A MOSFET is best suited for switching applications due to its:

A) High voltage drop

B) High input impedance

C) Slow response

D) Thermal instability

Answer: B) High input impedance

3. Which semiconductor device combines the characteristics of both MOSFET and BJT?

A) Diode

B) IGBT

C) SCR

D) Zener Diode

Answer: B) IGBT

4. Which power converter is typically used to convert DC to AC in an EV drive system?

A) Rectifier

B) Chopper

C) Inverter

D) Converter

Answer: C) Inverter

5. What is the main role of a thyristor in an EV control circuit?

A) Amplify signals

B) Allow AC to pass

C) Control high voltage power

D) Store energy

Answer: C) Control high voltage power

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Section B: EV Safety and Hazard Management (Understand & Apply)

6. Which one is a potential hazard while working on high-voltage EV systems?

A) Oil leakage

B) Electrical shock

C) Overheating tires

D) Radiator failure

Answer: B) Electrical shock

7. Which component is essential for safe disconnection of an EV high voltage system during maintenance?

A) Contact breaker

B) Safety switch

C) Precharge relay

D) Manual Service Disconnect (MSD)

Answer: D) Manual Service Disconnect (MSD)

8. What is a key safety precaution before servicing an electric vehicle?

A) Check coolant level

B) Disconnect 12V battery only

C) Deactivate the high-voltage system

D) Remove tires

Answer: C) Deactivate the high-voltage system

9. What should be used to safely handle EV components under high voltage?

A) Bare hands

B) Rubber gloves

C) Metallic tools

D) Wooden sticks

Answer: B) Rubber gloves

10. Which safety protocol is used to prevent EV battery fire hazards?

A) Oil cooling

B) Fusing the motor

C) Battery Management System (BMS)

D) Shielded metal casing

Answer: C) Battery Management System (BMS)

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Section C: Sensors and Autonomous Control (Understand & Apply)

11. Lidar and Radar sensors in EVs are mainly used for:

A) Power conversion

B) Motor control

C) Environment sensing

D) Battery charging

Answer: C) Environment sensing

12. Which of the following is NOT a potential risk to autonomous EV sensor systems?

A) Weather interference

B) Data hacking

C) Low tire pressure

D) Sensor misalignment

Answer: C) Low tire pressure

13. What is the function of a sensor in a self-driving car?

A) Generate power

B) Convert torque

C) Monitor surroundings

D) Store data

Answer: C) Monitor surroundings

14. Which of the following sensors can be targeted by hackers to disrupt EV navigation?

A) Motor sensor

B) Lidar

C) Fuel gauge

D) Speaker

Answer: B) Lidar

15. Which method improves safety by allowing an EV to operate without position sensors?

A) Hall effect sensor

B) Encoder-based detection

C) Sensor-less control method

D) Ultrasonic detection

Answer: C) Sensor-less control method

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Section D: Sensor-less Control Methods (Understand & Apply)

16. In phase flux linkage-based control, rotor position is estimated from:

A) Mechanical feedback

B) Phase voltage and current

C) Battery voltage

D) Lidar signal

Answer: B) Phase voltage and current

17. Which method is suitable for detecting rotor position at low speeds in sensorless control?

A) Hall sensors

B) PWM switching

C) Signal injection method

D) PID tuning

Answer: C) Signal injection method

18. Phase inductance-based control in EVs is primarily influenced by:

A) Frequency of switching

B) Rotor position

C) Inverter power loss

D) Sensor alignment

Answer: B) Rotor position

19. Observer-based control methods use:

A) Magnetic encoders

B) External sensors

C) Mathematical models of the motor

D) Camera-based detection

Answer: C) Mathematical models of the motor

20. Which of the following sensorless techniques works by injecting a high-frequency voltage?

A) Phase flux linkage

B) Observer-based method

C) Modulated signal injection

D) Mutually induced voltage-based

Answer: C) Modulated signal injection

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