By eliminating the use of physical connectors and cables, wireless charging provides a number of efficiency, cost and safety advantages over the traditional charging cable.
From smartphones, to hand-held industrial devices and heavy-duty equipment applications, wireless power maintains safe, continuous, and reliable transfer of power to ensure all varieties of devices and equipment are charged and ready to go at a moment’s notice.
What Is Wireless Charging?
Essentially wireless charging (a.k.a wireless power transfer) uses electromagnetic fields to safely transfer power from a transmitting source to a receiving device for the purposes of charging (or recharging) a battery. And as the name suggests, it does so without the use of a physical connection.
How Does Wireless Charging Work?
Wireless charging is based on the principle of magnetic resonance, or Inductive Power Transfer (IPT). This is the process of transferring an electrical current between two objects through the use of coils to induce an electromagnetic field.
The diagram below simplifies the process of wireless charging and power transfer into 5 key steps.
Transcript of wireless charging steps
- Mains voltage is converted into high frequency alternating current (AC).
- The alternating current (AC) is sent to the transmitter coil by the transmitter circuit. The alternating current then induces a time varying magnetic field in the transmitter coil.
- Alternating current flowing within the transmitter coil induces a magnetic field which extends to the receiver coil (when within a specified distance).
- The magnetic field generates current within the receiver coil of the device. The process whereby energy is transmitted between the transmitter and receiver coil is also referred to as magnetic or resonant coupling and is achieved by both coils resonating at the same frequency.
- Current flowing within the receiver coil is converted into direct current (DC) by the receiver circuit, which can then be used to charge the battery.
It’s through this process that power is safely transferred over an air gap. As well as any non-metal object that might exist between the coils. Such as wood, plastic or granite.
What Is ‘Resonant’ Wireless Charging?
You will often hear people talk about inductive and resonant technology in regards to wireless power. From a technical point of view, they are essentially one in the same. Inductive power transfer (as the overriding principle) uses resonance in order to achieve coupling of the transmitter and recover coil – achieved when the transmitter and receiver coils both oscillate – or ‘resonate’ – at the same frequency. This resonant frequency refers to the frequency at which an object naturally vibrates or rings. This is most commonly seen in the way a tuning fork can cause another to vibrate when both are tuned to the same pitch.
However in recent times, the term ‘resonant’ has taken on a slightly different meaning. What is now commonly referred to as Resonant wireless charging, is seen as an advancement on inductive capabilities in that it allows a number of advantages in relation to performance and convenience.
Some of the key advantages include:
- Greater spatial freedom: This refers to the ability to achieve coupling/power transfer with greater mis-alignment for the receiver and transmitter coil along the x, y and z axis. In a real-life scenario, this means not having to precisely align your smartphone or device on top of the transmitter in order for it to begin charging.
- Charging multiple devices simultaneously: Resonance promises the ability to charging more than one device at a time. How this is achieved from a technical point of view will depend on the coil geometry of the respective system, but nonetheless it provides an added convenience for larger transmitter surfaces such as table tops or work benches.
- Charging speeds: Charging speeds for devices will continue to be a major factor in the adoption of wireless charging. Current inductive charging solutions produce slower charge times compared to a wired charger. In the future, resonant promises improved efficiency for power transfer between the transmitter and receiver coils, which in turn increase the rate at which power is delivered to the battery for re-charging.
The Future Of Wireless Charging
No matter the device, industry, or application, the removal of the physical connection required for powering or charging devices delivers a number of benefits over traditional cable connectors – some of which aren’t immediately obvious.