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Wireless Charging technologies for electric highways

Introduction

An electric highway refers to a road or network of roads equipped with infrastructure that supports the charging of electric vehicles (EVs) as they travel. The goal of an electric highway is to provide a continuous and convenient way for electric vehicles to charge their batteries or receive power while on the move. This infrastructure aims to address the range limitations of electric vehicles and encourage their adoption by offering a seamless and efficient charging experience.

In this article, we will explore different charging technologies employed in electric highways, shedding light on their mechanisms, real-world applications, and their advantages & disadvantages.

1. Dynamic Inductive Charging Technology

Inductive charging technology operates on the foundational principle of electromagnetic induction. This wireless charging methodology facilitates the transfer of electric energy between a coil embedded in the road surface and a corresponding coil integrated into the EV. The operational sequence commences with the provision of an alternating current (AC) to the road’s embedded coil, thereby engendering an oscillating magnetic field.

As the EV, equipped with inductive charging capabilities, traverses the road, it encounters and passes over the embedded coils. This dynamic interaction induces an electric current in the coil located on the vehicle through electromagnetic induction. The ensuing current is subsequently converted back into direct current (DC) by the vehicle’s power electronics. This DC power finds utility in either recharging the EV’s battery or directly propelling its electric motor.

The notable feature of inductive charging lies in its wireless nature, obviating the necessity for physical connectors or cables. The intrinsic convenience of on-the-go charging positions it as a compelling solution for electric highways, offering a seamless and efficient means to replenish an EV’s energy reserves. Nonetheless, it is imperative to acknowledge challenges such as lower energy transfer efficiency compared to wired alternatives, along with considerations surrounding the infrastructure costs linked to embedding coils in road surfaces.

Advantages:

  • Convenience: No physical connection required, making it convenient for on-the-go charging.
  • Wear Reduction: No physical connectors mean less wear and tear over time.

Disadvantages:

  • Efficiency: Inductive charging may have lower energy transfer efficiency than wired charging alternatives.
  • Infrastructure Costs: Embedding coils in roads can be expensive, impacting widespread adoption.

2. Conductive Charging Technology

In a conductive charging setup, the road has special strips or rails designed to conduct electricity. A direct connection is established when an electric vehicle equipped with conductive charging capabilities comes into contact with these strips. This connection allows the flow of electric energy from the road infrastructure to the vehicle.

Think of it as an electrical handshake between the road and the EV. This direct physical contact ensures a swift and effective energy transfer, allowing the EV to charge up as it travels along the electric highway.

The efficiency of conductive charging makes it a compelling choice for powering EVs, especially for those on the move. However, it’s essential to note that precise alignment between the charging infrastructure and the vehicle is crucial for optimal charging performance. Additionally, as with any technology, the physical connectors have some wear and tear over time.

In essence, conductive charging offers an efficient and reliable solution for energising electric highways and ensuring a seamless charging experience for electric vehicles.

Advantages:

  • Efficient Transfer: Conductive charging offers efficient energy transfer due to direct physical contact.
  • Lower Infrastructure Costs: Compared to wireless options, conductive charging infrastructure may be more cost-effective.

Disadvantages:

  • Alignment Requirement: Requires precise alignment between the charging infrastructure and the vehicle for effective charging.
  • Wear and Tear: Physical connectors may experience wear and tear over time.

3. Overhead Wires (Catenary System)

Overhead wires, or the CATenary System, are a charging technology utilized on electric highways to power electric vehicles (EVs).

In the Catenary System, electric vehicles draw power from overhead wires, much like how traditional electric trains operate. These wires, suspended above the road, carry electric energy. A special device, often called a pantograph, is mounted on the EV. As the EV moves beneath these power lines, the pantograph connects to the wires, allowing the vehicle to draw the necessary electric energy for its operation.

While it provides a reliable and established charging solution, setting overhead wires can be challenging and expensive.

It is a dependable technology that offers an effective way to keep electric highways energized, especially suitable for larger vehicles in need of a robust charging solution.

Advantages:

  • Efficiency: Catenary systems have proven to be efficient for heavy-duty vehicles.
  • Established Technology: The catenary system is an established technology with a track record of reliability.

Disadvantages:

  • Aesthetics: Overhead wires may be considered less aesthetically appealing in certain environments.
  • Infrastructure Challenges: Installation of overhead wires can be challenging and expensive, particularly in urban settings.

Real-world applications

A quarter-mile section of road through the Corktown area of Detroit, USA, has been electrified using inductive charging technology by Electreon, a company that provides wireless charging solutions for EVs. The company also provides usage of electrified roads in the form of Charging-as-a-Service (CAAS), wherein customers can choose to pay a monthly subscription or pay for wireless EV charging as they use it.

Image credit: Photos by Stephen McGee/Michigan Central

In Italy, inductive charging technology has been used in a project on ‘Arena of the future’, a test project site for electrified roads, built on a section of a A35, a motorable road network that connects three provinces of the country.

Image Source: Brebemi website

Conclusion

The various charging technologies used in electric highways showcase a range of characteristics, addressing different needs and challenges. While inductive and conductive charging offer convenience and efficiency, dynamic wireless charging aims to eliminate the need for scheduled stops. The catenary system, with its proven track record, is well-suited for heavy-duty vehicles. Continuous advancements and ongoing pilot projects are shaping the future of electric highways, providing diverse and sustainable solutions for the growing electric vehicle market.

Also read: Tata Passenger Electric Mobility to work with multiple CPOs to set up 10,000 charging stations by FY 25.

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