Wireless Power Transfer (WPT) is a technology that allows the transfer of electrical energy wirelessly. Based on technologies that utilize electric, magnetic or electromagnetic fields, WPT is capable of delivering power from a standard AC source to compatible batteries and devices without any physical connectors. This technology uses the electromagnetic field generated by charged particles to transfer energy across the air gap, which is subsequently converted into household current usable by the receiver. Wireless power involves exchanging energy between two objects with a similar resonant frequency, while dissipating relatively little energy to the out-of-resonance foreign objects.
With rapid technological advancements, WPT technology, i.e. the wireless transmission of electrical energy from a power source to an electrical load without connecting wires, is particularly useful in wireless operation or charging of various products such as smartphones, tablets and laptops. transportation devices such as drones and electric vehicles (EVs), wearable electronics, transmitter applications, and solar cells. The technology has started to find increasing acceptance in various domains such as consumer electronics, transportation, heating and ventilation, industrial engineering, and model engineering.
WPT allows you to eliminate the limitation of a power cord while keeping electrical devices continuously charged. Reliable, efficient, fast and with low maintenance costs, it can also be used for short or long range. At the same time, this type of charging presents a much lower risk of electric shock as it is galvanically isolated.
WPT Evolution
The concept of WPT began in the late 19th century when Nikola Tesla, a Serbian-American inventor best known for his contributions to the design of alternating current (AC) power supply systems, proposed and worked on wireless power. Tesla displayed wireless light bulbs at the World's Columbian Exposition in the early 1890s. In early 1961, William C Brown proposed possibilities of microwave power transmission when he published a paper exploring the possibilities of microwave power transmission. In 2007, a team from MIT (Massachusetts Institute of Technology) successfully lit a 60 W lamp from a distance of 2 meters with an efficiency of approximately 40%. In 2009, Sony launched a wireless electrodynamic induction-powered TV set. In recent years, many experiments and advancements have taken place, leading to the advent of different wireless mobile chargers.
A demonstration test of a motorized bicycle was initiated by a team at Kyoto University in Japan. It involved a bicycle capable of receiving wireless charging by simply parking it in front of a charger. Its front wheel consumed energy in the form of microwaves with the help of a battery and a receiver. Tests that began in early March 2017 ensure that charging only takes place late at night to avoid potentially harmful human contact with microwaves equivalent to 100 watts. It is designed in such a way that it stops as soon as someone is within a certain range.
Wireless Power Transmission Market by Type
Induction method
Induction charging is used to make wireless charges for toothbrushes, cell phones, shavers and portable devices. The same principle is used in both wireless and transformer charging, where there is no direct connection between the primary and secondary coils. Mutual induction leads to the transfer of energy between the primary and secondary circuits. In this method, the induction coil of the charger acts as a primary coil and creates an alternating electromagnetic field when power is supplied to it. The portable device (which needs to be charged) contains the secondary coil that receives energy from this electromagnetic field when it is placed on the charger and converts it into electrical current and charges the battery. This fantastic principle is applied to charge devices within a minimum range.
It is advantageous, convenient and safe, as no dangerous conductors are exposed, causing no risk of electric shock. The same principle of resonant inductive coupling can be used for power transmission. Resonant inductive coupling increases transmission range. Here, the primary and secondary coils resonate at the same frequency. Electricity supplied to the primary coil generates an oscillating magnetic field and is captured by a secondary coil, which is converted into electricity for the load.
Another type of coupling is capacitive coupling or electrostatic induction. The principle involves capacitive coupling between two or more electrodes or plates with high-frequency, high-potential AC current.
All of the above principles are limited to small distances and cannot be implemented over larger distances.
Microwave power transmission
It was William C Brown who demonstrated wireless power transmission over greater distances through this method using Rectenna, an antenna with a rectifier device, in 1964. This method provides the feasibility of directional power transmission by a microwave transmitter, which generates microwaves using an antenna. The receiver has a Rectenna that converts microwaves back into electricity. One of the main obstacles of this method is that it needs large-scale antennas.
Transmission of energy by laser beam
This method uses photovoltaic cells, which convert light into electricity through the photovoltaic effect. First, the energy is converted into a laser beam and transmitted from the source. Photovoltaic cells are used as a receiver and convert the laser beam back into electricity. The cross-section of the laser beam is small and is advantageous for transmission over longer distances, but laser beams are harmful to humans and animals. Furthermore, it is highly directional, as the photovoltaic cells must be exposed to the transmitted laser beam; otherwise, total loss of power may occur. Other difficulties that can affect the efficiency of this system include atmospheric absorption, environmental dispersion effects and climatic difficulties.
Advantages of Wireless Power
Wireless power transmission and distribution has distinct advantages over wired connections and can achieve greater efficiency in the coming times.
Losses that occur during the transmission of electrical energy constitute a significant problem in power systems. Power loss during transmission is estimated at 26%. The main reason for this loss during transmission can be attributed to the resistance of the wires used in the network. According to WRI (World Resource Institute), India's power grid incurs the highest percentage (27-40%) of power transmission losses in the world. In this context, the transmission of electricity using an electromagnetic induction method can be highly useful.
Wireless power plays an important role in life-saving efforts. In disaster-prone areas, rapid recovery is possible with wireless power and significant damage to equipment can also be prevented. Remote power receivers dug into the earth when the danger level reaches the threshold, subsequently boosting and receiving power and distributing it to the required load.
WPT not only reduces the risk of shock and stopping frequent plugging in, but greater efficiency is also one of the critical factors to be considered in this technology.
Following are some other advantages of WPT:
- Simple design
- Lower frequency operation
- Potential for transmitting power to remote areas where wiring is not viable.
- Wireless power is not as dangerous as wired power where the conductors are exposed.
- The transmission and distribution losses of the existing system can further decrease when high-efficiency wireless power transmission is implemented.
- Electric vehicles can be charged anywhere.
- Customers can be freed from the requirements of power cords, plug-in cables, and plug-in adapters.
- WPT leads to reduced expenses and maintenance costs on transmission and distribution assets.
- Devices can be charged from anywhere without the need for chargers.
- Not prone to handshake theft from source to load.
- Increasing possibility of entry of more energy suppliers over greater distances with a consequent increase in the customer base.
- Competitive energy prices can be achieved when more suppliers participate in the market.
Disadvantages of Wireless Power
WPT also has its disadvantages. In addition to difficulties in transmitting and distributing electrical power, high capital cost and interference are also considerable bottlenecks in the commercial deployment of wireless power over long distances. More R&D efforts are needed to implement a wireless power system with safety, high efficiency and optimal capital cost while ruling out high power losses, non-directionality and inefficiency for longer distances.
The growth of the global wireless power transmission market may be affected to some extent due to the lack of common standards involving compatibility issues and trade-offs between security, efficiency and short range of wireless power.
Global Wireless Power Transmission Market Outlook
According to the “Global Wireless Power Transmission Market 2020-2026 Research Report”, the market is expected to grow at a CAGR of 21.89% during the forecast period from 2020 to 2025.
Main markets and players
The key regions of the wireless power transmission market include North America, Europe, Asia Pacific, South America, and the Middle East and Africa.
The Asia-Pacific region is expected to receive significant traction in terms of wireless power transmission market size due to the growing presence of a large number of consumer electronics industries in countries such as South Korea, India, Japan and China. Factors contributing to the wireless power transmission market in these countries include rapid urbanization and aggressive population growth, as well as a gigantic consumer electronics production hub.
Various companies operating in the global wireless power transmission market differ in terms of finances, R&D, strategies, expansion plans, and more.
Based in South Korea, Samsung Electronics has a powerful lineup of smartphones, such as the Samsung Galaxy, equipped with wireless charging receiver capabilities. Google Nexus and Motorola Droid make up some of the popular smartphone series that have wireless charging capabilities. TDK Corp., Integrated Device Technology, Inc., Texas Instruments Inc., Witricity Corp., Semtech Corp.; Toshiba Corp.; Panasonic Corp.; Rohm Co. LG Electronics Inc.; Murata Manufacturing Co. are some other leading companies in the global wireless power transmission market.
From now on
In the future, existing wired electricity communication may be replaced by wireless power. Soon, users won't need to carry charging devices or a power bank.
The market is likely to expand due to certain factors driving its growth. The requirement for effective charging systems and growing consumer preference for wireless connectivity and the convenience offered are expected to enhance the prospects of vendors operating in the global wireless power transmission market. In the future, the international wireless power transmission market may witness the rise of magnetic resonance technology, paving the way for the introductory phase and inductive technology for the growth phase.
Smartphones are emerging as the largest receiving application in the wireless inductive power transmission market. Among the various technologies for transmitting electrical energy from one point to another over shorter distances, inductive coupling is the most commonly used for very short distances in mobile charging.
Lately, one of the leading mobile device manufacturers has filed a patent based on RF-based wireless power for wireless charging of mobile devices. Scheduled charging of your devices can lead your competitors to conduct research and development into futuristic wireless charging installations.
In the future, a mobile service provider may be able to successfully charge cell phones by providing the necessary power from a mobile base station. The synergy between mobile integrated software and hardware and the base station takes care of the power threshold level for charging, which can lead to greater efficiency.
Trends point to wireless charging points at signs for EVs. Charging EVs while driving longer distances may not be a barrier to replacing existing vehicles. Special roads can be built between utilities and maintained with inductive coupling to provide continuous charging for EVs. Each EV is identifiable from the source's perspective. Alternative charging possibilities may arise through the construction of roads for constant charging of EVs.
Opportunities in various segmentation markets such as integrated implementation and induction technology are anticipated to offset the effect of impediments in the global wireless power transmission market. In this emerging technology, the energy transfer distance can be improved with continuous R&D efforts. Furthermore, the WPT is expected to mitigate the serious energy crisis that the entire world is currently facing. As this technology is constantly evolving, wireless power may become a more realistic proposition in the future.