Technology and Principles
The transition to sustainable transportation has spurred innovations in electric vehicle (EV) infrastructure. One notable advancement is Dynamic Wireless Power Transfer (DWPT), a system that allows EVs to charge while in motion on specially equipped roads. By integrating charging technology into the roadways, DWPT offers benefits such as reduced battery size requirements, extended vehicle range, and a transformed energy ecosystem for transportation.
This technical seminar report explores the working principles, core technologies, challenges, and future prospects of DWPT systems.
Principles of DWPT
Dynamic Wireless Power Transfer is based on inductive coupling, a method of transferring energy between two coils via a magnetic field. In DWPT:
- Primary coils (transmitters) are embedded under the road surface.
- Secondary coils (receivers) are mounted on the underside of the vehicle.
- As the vehicle moves over the road, alternating current (AC) in the primary coil generates a time-varying magnetic field.
- This magnetic field induces a current in the secondary coil, thus wirelessly charging the EV’s battery or directly powering its motor.
This process mirrors static wireless charging used in consumer electronics, but DWPT adds complexities of vehicle motion, alignment, safety, and power management.
Key Technologies in DWPT
1. Inductive Power Transfer (IPT)
At the heart of DWPT is IPT technology operating typically between 20 kHz and 150 kHz frequencies. Advanced coil designs, such as double-D, double-D quadrature (DDQ), or Solenoidal configurations, are employed to maximise power transfer efficiency while minimising magnetic losses.
2. Power Electronics and Control Systems
Power is managed through inverters, rectifiers, and DC-DC converters that:
- Convert grid-supplied electricity to high-frequency AC suitable for transmission.
- Regulate power flow based on vehicle speed, position, and load.
- Coordinate multiple charging segments through dynamic control algorithms ensuring smooth power handover.
3. Communication Protocols
DWPT systems use Vehicle-to-Infrastructure (V2I) communication for:
- Authentication and billing.
- Real-time energy transfer adjustments.
- Vehicle positioning information for optimal coil activation. Standards like ISO 15118 are adapted for wireless energy transfer communications.
4. Road Infrastructure Integration
DWPT modules are modular and installed below the road surface without major structural disruption. They consist of:
- Embedded primary coils.
- Power conditioning cabinets are placed at roadside intervals.
- Connection to the grid or renewable energy sources.
Materials must withstand weather, mechanical loads, and thermal stresses while maintaining electromagnetic performance.
Challenges
Despite its promise, DWPT faces several technical and practical challenges:
- Efficiency Losses: Misalignment between coils, vehicle height variations, and speed affect transfer efficiency (typically 80–90%).
- Cost and Scalability: High initial costs for installing and maintaining electric roads.
- Electromagnetic Compatibility (EMC): Ensuring minimal interference with nearby electronic devices and biological safety compliance (e.g., ICNIRP guidelines).
- Standardisation: Interoperability between vehicles and infrastructure built by different manufacturers is still under development.
- Durability: Roads must be resilient against environmental wear without degrading electrical performance.
Case Studies and Deployments
Pilot projects have demonstrated DWPT’s feasibility:
- Electreon in Sweden and Israel has trialled DWPT on public roads with buses and freight trucks.
- DAEWPT (Dynamic Autonomous Electric Wireless Power Transfer) in Korea successfully powered buses wirelessly at speeds up to 70 km/h.
- Stellantis and other automotive manufacturers have tested DWPT on special test tracks (e.g., “Arena del Futuro” in Italy).
Future Prospects
The vision for DWPT is to create electric corridors where EVs, buses, and freight trucks can operate continuously without frequent stops for charging. Potential enhancements include:
- Integration with smart grids and renewable energy.
- AI-based vehicle tracking for predictive energy distribution.
- Batteryless or ultracapacitor-powered vehicles rely entirely on DWPT for energy needs.
Standardisation efforts, cost reductions, and improved efficiency could make DWPT a mainstream solution for sustainable mobility within the next decade.
Conclusion
Dynamic Wireless Power Transfer represents a transformative approach to EV charging, potentially overcoming range anxiety and infrastructural bottlenecks. Though technical challenges remain, ongoing research and pilot implementations show that DWPT could soon be a vital part of our transport infrastructure, paving the way for cleaner, more efficient electric mobility.
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