Resonant Wireless Charging

Wireless charging provides an easier and more convenient means to powering a range of Consumer Electronic and Industrial devices. It provides a reliable and low maintenance solution for power transfer compared with traditional cable based contact methods.

From smartphones and small electronic devices to mission critical equipment, wireless charging maintains safe, reliable transfer of power to ensure all forms of device and equipment are always charged and ready to go.

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How does wireless charging work?

Wireless charging is based on the principle of Wireless Power / Inductive Power Transfer (IPT) or Magnetic Resonance – the process of transferring energy between two objects through coils. A time varying magnetic field is induced in the transmitter coil by an alternating current (AC).

This sends energy from the charging base station (transmitter) to a coil in the target device (receiver) via a process called magnetic coupling. Specialized circuitry on the receiver converts energy received through the magnetic coupling into DC which can then be used to charge the battery.

How Resonant Wireless Charging Works

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  1. Mains voltage is converted into high frequency alternating current (AC).
  2. The alternating current is sent to the transmitter coil by the transmitter circuit.
  3. Alternating current flowing within the transmitter coil creates a magnetic field which extends to the receiver coil (when within a specified distance).
  4. The magnetic field generates current within the receiver coil of the device.
  5. Current flowing within the receiver coil is converted into direct current (DC) by the receiver circuit, thus charging the battery of the device.

These basic principles are applied for inductive charging of consumer devices i.e charging pads, as well as for large industrial wireless solutions.

This DC power can charge the battery or power a device without contact.

Power can be transferred safely over the air gap and also through objects which might exist between the coils.  The addition of extra (or larger) transmitter coils extends the range at which the power can be transferred.

For over 20 years, PowerbyProxi and The University of Auckland have achieved greater transfer distances and higher efficiency through resonance – whereby the transmitter and receiver coils oscillate (or resonate) at the same frequency.  This resonant frequency refers to the frequency at which an object naturally vibrates or rings – much like the way a tuning fork rings at a particular frequency and can achieve their maximum amplitude.

Check out the video for a visual explanation of how wireless charging works:

Video Transcript:

“The wireless power transmitter presses an AC signal to the transmit coil. Current flowing through the coil induces a magnetic field that is minded in all directions. When a second coil is brought in range of the first, the oscillating magnetic field induces current in the received coil. Power can be transferred through solid objects such as walls, house hold furniture and human tissues. Introducing a third coil extends the range of the wireless power transfer. Additional circuitry converts the AC signal into a DC voltage, compatible with any application, including implanted devices.”

Some of the associated benefits of wireless chargers:

  • Greater convenience and ubiquity for charging of everyday devices
  • Reduce cost associated with maintaining mechanical connectors
  • Safe powering or charging devices that need to remain sterile or hermetically sealed (waterproof)
  • Prevent corrosion due to elements such as oxygen and water
  • Eliminate sparks and debris associated with wired contacts

Wireless charging for smartphones & tablets

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Current options for wireless charging of smartphones and tablets involve the use of a charging pad which acts as the transmitter, transferring power to a miniaturized wireless receiver integrated into the smartphone or tablet.

The Proxi 2D Charging Solution is the safest and most efficient wireless charging pad technology for smartphones, phablets and tablets, delivering simultaneous wireless charging of multiple devices, with full spatial freedom for the placement of devices in any position (no exact alignment). Miniaturized receivers are integrated directly into the device, removing the need for external housing covers or sleeves on devices.  Follow the link to read more about our Proxi 2D Charging pad technology.

With continued advances in wireless charging technology, transmitters built into workstations, desks, tables and a whole range of everyday furniture will soon become a reality.

Proxi-2D Charging System

Wireless charging for Wearables and devices using AA batteries

3D bowl 3Proxi-In-Device

In order to truly deliver wireless charging for all consumer electronic devices, the technology needed to somehow enable charging of irregular shaped objects i.e. not thin form or flat in shape.  Such devices commonly use AA batteries, or specialized small batteries in the case of wearable devices.  As a result PowerbyProxi designed the worlds first 3D wireless charging transmitter, capable of holding and wirelessly charging multiple irregular shaped devices at one time.  To enable wireless charging for these devices, we built the world’s first wirelessly rechargeable AA battery and integrated miniaturized wireless receiver for wearable devices, meaning that hundreds of millions of everyday devices can be charged wirelessly within the unit, without removing the batteries from the device.

We call this In-Device charging and it means convenient, simultaneous charging of multiple devices including remotes controllers, gaming devices, cameras, toys, wearable technologies and more – without having to remove and replace batteries.

Proxi-3D In-Device Charging

The Future of Wireless Charging

See our vision for wireless charging in the future:

Wireless Charging in Industrial Applications

PowerbyProxi has pioneered the application of inductive power for industrial applications since 2007, enabling equipment suppliers to deliver mission critical wireless power systems in wet, dirty and moving environments.


With a range of one-to-one and one-to-many wireless power transfer solutions, our Proxi-Point solution is ideal for supplying power and data to control systems and process automation equipment, providing a reliable and maintenance free alternative to traditional cable based connectors.

The system can operate at a range of input voltages and is available as a plug and play modular system to improve power supply and battery charging in new or existing equipment.

More on Proxi-Point

Wireless sensors and sensor networks play an important part in the industrial wireless industry. Read more on wireless sensors and wireless sensor networks.

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