About this previous year paper
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
| Lumped Model | Distributed Model |
|---|---|
| Simple | Complex |
| Discrete parameters | Continuous parameters |
| Suitable for low frequency | Suitable for high frequency |