(SEM VI) THEORY EXAMINATION 2024-25 ENERGY HARVESTING TECHNOLOGIES AND POWER MANAGEMENT FOR IOT DEVICES

BCIT061 – ENERGY HARVESTING TECHNOLOGIES AND POWER MANAGEMENT FOR IoT DEVICES

Time: 3 Hours | Max Marks: 70

SECTION A – Short Answer Questions

(2 × 7 = 14 marks | Attempt ALL)
 
Write definition + 1–2 key points

1. Energy Harvesting & Energy Sources

Energy harvesting is the process of capturing small amounts of energy from the environment and converting it into electrical energy.
Sources: Solar, vibration, thermal, RF.

2. Photovoltaic (PV) Cell

A photovoltaic cell converts solar energy into electrical energy using the photoelectric effect.
Type: Monocrystalline silicon cell.

3. Piezoelectric Materials                                Commonly used materials:

PZT (Lead Zirconate Titanate)                         Quartz

4. Lumped Parameter Model

A model in which system parameters (mass, stiffness, damping) are assumed to be concentrated at discrete points.

5. Principle of Electromagnetic Energy Harvesting

It works on Faraday’s law of electromagnetic induction, where relative motion between a magnet and coil induces voltage.

6. Power Conditioning Losses

Losses occurring in rectifiers, voltage regulators, DC-DC converters, and energy storage interfaces.

7. Applications of RF Energy Harvesting

Wireless sensor nodes

RFID systems

SECTION B – Medium Answer Questions

(7 × 3 = 21 marks | Attempt ANY THREE)

Write principle → explanation → example/diagram

1. Electric Power Generation in PV Cells                          Incident photons generate electron–hole pairs

Built-in electric field separates charges                           Current flows through external circuit
Explain with energy band diagram.

2. Piezoelectric Transducers                                             Convert mechanical strain into electrical charge

Used in vibration-based energy harvesting                     Examples: Sensors, wearable devices.

3. Microfabricated Coils in Electromagnetic Harvesting

Small-scale coils fabricated using MEMS                            Improve integration with micro devices

Used in low-power IoT systems.

4. Power Sources for Wireless Sensor Networks (WSN)      Batteries

Solar energy                                                                        Piezoelectric energy

Thermal energy                                                                   Energy harvesting increases network lifetime.

5. Bio-MEMS-Based Energy Harvesting                     Uses biological systems or body energy

Suitable for implantable medical devices                   Low power, biocompatible.

 SECTION C – Attempt ANY ONE

(7 marks)

1. Types of Photovoltaic Cells                                     Monocrystalline silicon

Polycrystalline silicon                                                  Thin-film solar cells

Organic solar cells                                                       Compare on efficiency and cost.

2. Electric Power Generation in a PV Cell

Explain:                                                                        PN junction

Photoelectric effect                                                     Current–voltage characteristics
Include neat diagram.

SECTION D – Attempt ANY ONE

(7 marks)

1. Electromechanical Modeling (Lumped Parameter Model)

Mechanical domain: mass, spring, damper                                   Electrical domain: voltage, current

Coupling through transducers                                                      Used for analyzing vibration harvesters.

2. Lumped vs Distributed Parameter Models