IIT Madras

Overview

The Department of Engineering Design at IIT Madras is one of India's most active hubs for interdisciplinary research - spanning autonomous vehicles, robotics, electric mobility, and energy systems. I joined the wireless power transfer research group under Dr. Deepak Ronanki, working on a problem that is quietly reshaping how electric vehicles will charge in the near future: how do you transfer tens of kilowatts of power across an air gap - with no physical connection - safely, efficiently, and within international radiation safety limits?

That was the problem. My job was to design the coils and simulate the physics.

The Problem Worth Solving

Wireless charging for EVs sounds simple until you realize the engineering behind it. At 85kHz operating frequency, the system generates alternating electromagnetic fields strong enough to transfer meaningful power - but those same fields pose risks to human safety and nearby electronics if they leak beyond the intended transfer zone.

International safety standards (ICNIRP) cap allowable magnetic field exposure at just 27 μT at 85kHz. Every coil geometry, every shielding decision, every millimeter of design is a negotiation between power transfer efficiency and electromagnetic containment.

3D Coil Structures Designed

I designed and modelled 3 distinct coil architectures - each representing a different engineering philosophy:

All structures were also modelled with Litz wire configurations - the industry standard for minimising resistive losses at high frequency. Every model was built from scratch in CAD before being imported into simulation.

ANSYS Simulation & Analysis

All coil structures were imported into ANSYS Electronics Desktop and run through eddy current analysis at 85kHz - the standard operating frequency for EV wireless charging. The simulation pipeline:

Each coil was placed inside an air region, assigned 90A RMS current with three-phase excitation at 0°, 120°, and 240°. Matrix assignments mapped all current paths. Mesh operations were validated and simulations run - producing a full self and mutual inductance matrix for every structure.

Self-inductance values for the triangular phase coils settled around 38μH - a key baseline for system resonance tuning. Both primary-only and primary-secondary configurations (separated by 150mm air gap) were analyzed. Multiple rounds of iteration with ANSYS support specialists refined the methodology before final results were locked in.

Electromagnetic Shielding Research

Beyond coil design, I conducted a comprehensive study of shielding strategies - because a great coil design means nothing if the EMF leaks outside the safety envelope.

• Passive Shielding - Aluminum

  Aluminum shields work by generating eddy currents that oppose the leakage field through Lenz's Law. At 85kHz, the skin depth in aluminum is just 0.28mm - meaning nearly all shielding action happens in a razor-thin surface layer. Three approaches were studied:

  • Solid plates: Strong shielding but high I²R losses and reduced coupling efficiency.
  • Laminated sheets: 10 layers of 0.2mm foil cut eddy current losses by 31% and improved pad efficiency from 91.8% -> 94.1%.
  • Slotted/patterned: Radial and honeycomb patterns reduced coupling losses by 5-8% while improving thermal management.
• Passive Shielding - Ferrite Ferrite tiles guide magnetic flux along desired paths rather than blocking it - high permeability without eddy current losses. Best practice combines ferrite backing with laminated aluminum for a hybrid system that handles both flux guidance and EMF containment simultaneously.
• Active Shielding Active systems use powered cancellation coils to destructively interfere with leakage fields. More adaptive, but more complex - studied as a future direction rather than current implementation standard.

Internship Artifacts & Certification

Official project documentation and training certification from my research internship at IIT Madras:

IIT Certificate.pdf

Click to open PDF Certificate