Wireless power transfer

Wireless power transfer

Inventor and engineer Nikola Tesla, 'the man who invented the 20th century' theorized about wireless electricity back in the 1890s. He even demonstrated the principle by lighting up glass tubes with wireless power transmission.
Nikola Tesla wanted to create the way to supply power without stringing wires. He almost accomplished his goal when his experiment led him to creation of the Tesla coil. It was the first system that could wirelessly transmit electricity.

Wireless power transfer (WPT), wireless power transmission, wireless energy transmission (WET), or electromagnetic power transfer is the transmission of electrical energy without wires as a physical link.
Wireless power transfer (WPT) is one of the hottest topics being actively studied, and it is being widely commercialized. In particular, there has been a rapid expansion of WPT in mobile phone chargers, stationary charging electric vehicles (EVs), and dynamic charging EVs, also called road-powered EVs (RPEVs). It is expected that WPT industry will grow persistently in the coming decades.
Wireless power transfer (WPT), in its general term, has been around us for decades in applications such as telemetry, satellite communications, and radio frequency identification (RFID) tags.

Wireless electricity sounds like science fiction, but the technology is already realized and primed for a utility-scale case study. And in this first-of-its-kind pilot program, Powerco—New Zealand’s second-largest electricity distributor—will test Emrod technology beginning in 2021.

Watch Video-->Emrod | The World's First Commercially Viable Long-Range Wireless Transmission Technology

In a wireless power transmission system, a transmitter device, driven by electric power from a power source, generates a time-varying electromagnetic field, which transmits power across space to a receiver device, which extracts power from the field and supplies it to an electrical load. The technology of wireless power transmission can eliminate the use of the wires and batteries, thus increasing the mobility, convenience, and safety of an electronic device for all users. Wireless power transfer is useful to power electrical devices where interconnecting wires are inconvenient, hazardous, or are not possible.

WPT systems allow power to be transferred from one electrical network to another without the need for wires or exposed contacts. For a large number of diverse applications, this feature is highly advantageous, and in certain cases has enabled new applications to be realized. Further, WPT is poised to play a vital role in the worldwide drive to electrify transportation systems and, thus, become ubiquitous throughout technologically advanced future societies. Therefore, knowledge in the area of WPT is increasingly important for the modern power electronics engineer. In this chapter, various WPT techniques are described, before a focus is developed on inductive power transfer, IPT, systems. Fundamental and essential knowledge related to the design of IPT circuits and control methods is then presented.

Power can be transferred over short distances (near-field transfer) by alternating magnetic fields and inductive coupling between coils, or by alternating electric fields and capacitive coupling between metal electrodes. Inductive coupling is the most common method of WPT and is used in charging devices such as smart phones, electric shavers, visual prostheses, and implantable medical devices (cardiac pacemakers, cochlear implants) (Sun et al., 2013; Moorey et al., 2014) (Fig. 16). For 20 mm distance separation and size of the coil pair, loop diameter, and frequency play a major role in determining WPT performance (Celik and Aydin, 2017). The companies plan to deploy the prototype wireless energy infrastructure across a 130-foot expanse. To make it possible, Emrod uses rectifying antennas, a.k.a. “rectennas,” that pass microwaves of electricity from one waypoint to the next: a solution well-suited to New Zealand’s mountainous terrain. Specialized square elements are mounted on intervening poles to act as pass-through points that keep the electricity humming along, and a broader surface area “catches” the entire wave, so to speak.
“We’ve developed a technology for long-range wireless power transmission,” says Emrod founder Greg Kushnir. “The technology itself has been around for quite a while. It sounds futuristic and fantastic but has been an iterative process since Tesla.”
The link to Nikola Tesla, Kushnir admits, is more of an imaginative, feel-good tale than a true genealogy. Tesla considered wireless power in the 1890s, as he labored over his breakthrough “Tesla coil” transformer circuit that generated alternating current electricity, but he couldn’t prove that he could control a beam of electricity across long distances. “The sheer fact that he could imagine it is remarkable, but the sort of technology he was looking to apply wouldn’t have worked,” Kushnir says.
Emrod, by contrast, can keep the beam of electricity tight and focused with two technologies. The first is transmission-related: Small radio elements and single wave patterns create a collimated beam, which means that the rays are aligned in parallel, and will not spread much as they propagate. Second, Emrod uses engineered metamaterials with tiny patterns that effectively interact with those radio waves.

Source: Few websites, Wikipedia...