Wireless power: Present and future developments

WPT Wireless power: Present and future developments

2024-07-16 From Venus Kohli 5 min Reading Time

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Have you ever heard about an electric pad charging smartphones without a wired cord? The answer is “Wireless Power Transfer”. Once a big project of Nikola Tesla, wireless power was a hypothetical concept in the early nineteenth and twentieth centuries- imagined to empower locomotives. The article explains wireless power with its present status and the scope for future developments.

Near-field wireless power technology is gaining traction for consumer electronics and medical devices, with promising advancements in areas like magnetic diodes and dynamic charging for electric vehicles.(Source: MAY - stock.adobe.com) — Near-field wireless power technology is gaining traction for consumer electronics and medical devices, with promising advancements in areas like magnetic diodes and dynamic charging for electric vehicles.
(Source: MAY - stock.adobe.com)

Wireless Power Transfer or Wireless Power Transmission, abbreviated as WPT, is a process in which electrical energy is transmitted without wires. Wireless power is transmitted as a time-varying electromagnetic field between the source and the receiver. The receiver device extracts power and delivers it to the load.

Wireless power transmission is classified into two types: Near-field (non-radiative) and Far-field (radiative). Far-field wireless power transmission involves microwaves, radio frequencies, radar systems, and satellite communication systems. Far-field wireless power transmission has laid the foundation of modern telecommunication systems. However, the article emphasizes near-field wireless power transfer.

How does near-field wireless power transfer work?

The explanation is based on Faraday’s laws of electromagnetic induction (inductive coupling). Other methods are capacitive and resonant-inductive coupling. An AC current flows in the transmitter coil. It generates a time-varying magnetic field which oscillates at a certain frequency. The magnetic field propagates through space and reaches the receiver.

A generic block diagram of a wireless power system.(Source: / CC0) — A generic block diagram of a wireless power system.
(Source: / CC0)

The time-varying magnetic field induces a magnetic flux. As a result, an electromotive force is generated in the receiver coil. To “wirelessly” transfer power from the transmitter to a device, the device must be in direct contact or kept near the transmitter (Typically less than 1 meter).

Present usage: Wireless power integration

Integrating near-field wireless power systems in real-world applications eliminates the need for bulk wiring and metal conductor deployment. It drastically decreases the cost of implementation and improves safety and on-site mobility. From a manufacturer’s perspective, integrating wireless power transmission capabilities offers minimalistic design solutions and cuts down on costs.

Consumer electronics

A mainstream wireless power device is a charging pad to charge smartphones, laptops, tablets, computer mice, video game controllers, electric toothbrushes, and electric razors. Both chargers and devices must be compatible and interoperable. Other popular consumer electronic devices include induction cookers and RFID card reading through simple tapping.

Wireless charging pat for LG smartphone, using the Qi international inductive power standard published by the Wireless Power Consortium (WPC).(Source: Inductive charging of LG smartphone (2) /LG전자 / CC BY 2.0) — Wireless charging pat for LG smartphone, using the Qi international inductive power standard published by the Wireless Power Consortium (WPC).
(Source: Inductive charging of LG smartphone (2) /LG전자 / CC BY 2.0)

Medical equipment

Many under-the-skin implantable biomedical devices including artificial cardiac pacemakers and neiurostimulators are already using near-field wireless power transfer to avoid surgery for replacement. In addition, this technology provides a power supply to a capsule endoscope. Captured images and data enable gastroenterologists to diagnose medical conditions.

Renewables

Wireless power transmission is also known as Wireless Energy Transfer (WET) in renewable applications. Wireless charging infrastructure in parking lots fixes charging coils in the ground. It enables effortless charging of electric trams and vehicles. Recently, a light-duty EV was fully charged, setting up a world record.

An electric vehicle can be defined as any vehicle that uses one or more electric or traction motors for propulsion. (Source: gemeinfrei)

Energy harvesting

Energy harvesting is the conversion of ambient energy (heat, vibration, light) into electric power. Applications include kinetic energy-generating bicycles, IoT-based wireless sensor networks, biomedical implants, and wearables. In the case of renewables, wireless power transfer is used with solar cells and piezoelectric devices.

Drones

Wireless power technology is implemented to charge UAVs (Unmanned Aviation Vehicles) or drones. UAVs are needed in the industry to inspect transmission lines and locate faults in high towers. A new technology enables wireless charging of drones through transmission lines to increase flight time.

Present status

The wireless power transfer market is booming. Despite limitations like range and efficiency, innovations like magnetic diodes, dynamic charging for EVs, and solar power satellites are paving the way for a future powered without wires.

Market valuation

Contrary to popular belief, the wireless power transfer market is a billion-dollar business. At present, the wireless power transfer market is valued at USD10.22 billion. By 2031, the market valuation is expected to reach 43.96 billion at a high CAGR of 20 %.

Limitations

Near-field wireless power transfer has a low range and efficiency. In addition, near-field wireless power transmission incurs high losses and EMI (Electromagnetic Interference). In automotive and transportation applications, unreliability cannot be compromised by choosing less wiring as safety is the main concern.

Future developments

Near-field wireless power is growing rapidly in the applications mentioned below. Some of them are in testing phases while others are futuristic.

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IoT applications

For IoT-based applications, near-field low-range wireless power transmission is more efficient than far-field wireless power transmission. A coil can be embedded inside a wall or mounted on the ceiling to enable IoT-based home automation. In such cases, LED lights, air conditioners, TVs, music players, and other smart devices can be turned on and off through wireless power solutions.

Industrial IoT applications

SWIPT (Simultaneous Wireless Information and Power Transfer) is a method to transmit information and power without wires. Researchers in South Korea combined SWIPT with NOMA (Non-Orthogonal Frequency Division Multiplexing) in DAS (Distributed Antenna System) to extend the battery life of devices in industrial IoT applications. This technology is somewhat similar to talkative power.

The Internet of things (IoT) is a system of interrelated computing devices, mechanical and digital machines provided with unique identifiers (UIDs) and the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. (Bild: Stock Adobe)

Magnetic diodes

Recently, Physicists at the University of Innsbruck, Austria, have constructed the world’s first “magnetic diode”. A diode is a device that allows the unidirectional flow of current. This magnetic diode allows magnetic fields to flow in only one direction. The new invention can revolutionize the wireless charging of EVs and improve magnetic coupling elements in MRI machines.

Dynamic charging

Dynamic charging is a concept that enables battery charging while the EV is at rest or still in motion. Wireless power integration at rest decreases reliance on charging stations. When an EV is in motion, dynamic charging can bring effective results to eliminate the tension of repeated temporary halts and improve mobility range.

Power electronics

One of the most critical power electronics issues is to ensure proper heat management. High-current and voltage applications heat the devices and bulky wires. Implementing wireless power transmission with heat sinks is a simple way to maintain safety. At present, wireless power transmission is possible for low-power applications. High-power near-field wireless power transfer is hypothetical.

Solar satellites

When compared to far-field wireless power, near-field wireless power transfer can be much more powerful in space due to its unique conditions and negligible risk of human intervention. Power beaming is a technology that utilizes solar satellites to collect solar power in space and distribute it to Earth. Such a technology has been in testing phases since the seventies. In 2024, Caltech successfully transmitted wireless power in space with its SSPD launch (Space Solar Power Demonstrator).

This picture shows a suntower in space.(Source: / CC0) — This picture shows a suntower in space.
(Source: / CC0)

Underwater environments

Deploying wired charging cables is not always possible in harsh environments like the underground and deep ocean floors due to extreme pressure conditions. In such cases, wireless power transfer can be beneficial for small underwater devices that have low charging periods such as cameras and sensors. Apart from underwater deployments, humid and coastal areas are also good examples.

References

www.sciencedirect.com
www.mdpi.com
www.uibk.ac.at
www.ornl.gov
www.sciencedaily.com
www.caltech.edu
artsandculture.google.com

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