Wireless Charging | How Does It Work

Wireless charging or more familiarly known as “wireless charging” is starting to arm smart devices circulating today such as cellphones and smart watches.

The technology that works like magic is able to offer a future feature that can allow users to charge devices without the need for a cable connection.

Wireless Charging | How Does It Work
Wireless Charging | How Does It Work

Wireless Charging | How Does It Work

However, wireless charging is not a fairly new technology as it has been around since 1894 when M. Hutin and M. Le-Blanc proposed a device and method for driving electric vehicles.

How does it work? Is this technology safe to use? Let’s get acquainted with what wireless charging is so you know what the advantages and disadvantages are when using it.

What is Wireless Charging

Wireless charging today has many names. This wireless charging technology is also called by several terms such as inductive charging and cordless charging.

As the name it uses, this technology offers the transfer of electrical energy from a power source to a device without a connection in the form of a cable via a micro USB port, USB Type-C, or lightning.

When charging the device, users only need to get closer to the charging transmitter, which in general can be in the form of a charging pad, stand, or station.

A device that runs out of power is usually simply placed on it and after that it will automatically start the battery charging process if the transmitter is connected to a power source.

But at this point, don’t get me wrong. Even if translated includes the term “wirelessly”, this does not mean that wireless charging technology actually works without the use of cables at all.

In order for this to work, the technology still requires cables like conventional charging. It’s just that, there is a little difference because the interface is no longer in the form of a USB port that needs to be connected directly but in the form of a transmitter and receiver component.

Because of this, the user does not need to plug the cable into the device, but rather because he is sufficient to keep the transmitter and receiver close together until they are both able to establish a connection and transmit power.

Wireless Charging Working Principle

At school, you may have heard the term “electromagnetic induction”, which is a phenomenon of the emergence of an electromotive force due to a change in the magnetic flux in the coil.

The flux itself can be imagined as the lines generated by a magnetic field in a field. Meanwhile, the electromotive force refers to the potential difference between the two poles which can cause an electric charge to flow.

Just like generators and dynamos, wireless charging technology also takes advantage of this electromagnetic induction phenomenon, but not to create a power source but as a method of power transfer.

Wireless charging generally makes use of two coils in this case. The former is a magnetic field transmitter, while the second captures flux changes to trigger an electromotive force.

To produce a change in magnetic flux in the system, wireless charging technology does not use mechanical motion which is generally used in generators or dynamos.

Instead of making use of object motion such as turning a coil, this futuristic charging technology immerses an electronic circuit that can create oscillations (periodic alternations) of magnetic fields in the transmitter.

The oscillation of the magnetic field from the transmitter will affect changes in the flux in the second coil so that an electromotive force will arise and it can direct an electric charge to the battery or circuit in the device.

In today’s mobile industry, most companies (including Apple, Asus, Google, HTC, Huawei, LG Electronics, Motorola Mobility, Nokia, Samsung, BlackBerry, Xiaomi, and Sony) apply wireless charging technology through a standard called Qi.

Qi Wireless Charging standard

Qi Wireless Charging is a low-power wireless charging technology interface standard for small devices developed by the Wireless Power Consortium, a consortium of multinational technology companies in the field of wireless charging.

The standard, which was introduced since 2009, supports wireless charging up to a distance of 4 cm with a special device called the Base Station for the transmitter and Mobile Devices as the receiver.

As for the charging capabilities offered, each device may differ depending on the version used. As of this article published in 2021, there are at least five versions of Q Wireless Charging in this regard.

Qi Wireless Charging Technology Version

Version (Year) Maximum Power Information
1.0 (2010) 5 W Can work 3 types of transmitter coils
1.1 (2012) 5 W 12 transmitter specifications, added metal detector and USB power transmitter
1.2 (2015) Baseline Power Profile (BPP): 5W
Extended Power Profile (EPP): 15 W
Improved thermal test, timing specifications, foreign body detection sensitivity and transfer power up to 15W
1.2.3 (2017) EPP Power Class 0: 5W – 30W Addition of Power Class 0 which allows the use of a charger up to 30W
1.2.4 (2017) n / a n / a

Qi Wireless Charging is certainly not the only wireless charging technology standard used by manufacturers in arming a wide variety of devices.

However, the application of standard wireless charging technology in general has several advantages and disadvantages which are very evenly distributed, as in the following details.

Advantages of Wireless Charging

  • Easy to use as they simply place the device on top of the charging pad
  • The connection is safer from problems arising from corrosion or short-circuiting from water splashes on the USB port
  • Minimizes installation errors such as inverted ports or wrong wiring
  • Without the plug and play connector, this technology has very high resistance

With some of the advantages above, unfortunately wireless charging technology still has several weaknesses when applied.

Weaknesses of Wireless Charging

  • Requires special components, both on the charger side and the device to be charged
  • Compared to conventional charging that has adopted the fast charging feature, wireless charging has a slower charging speed
  • Adoption costs are high so it’s more often available on premium devices nowadays
  • Efficiency is still very small which can make the charging process more wasteful of electric power
  • The limited distance of 4 cm makes the device less flexible to use unless the user is ready to take the risk of the battery being damaged quickly due to detachment from the charging pad
  • Based on research, wireless charging technology also causes excessive heat which is not good for the device

Wireless charging technology is still very limited at this time. However, it does not rule out the various kinds of weaknesses above can be resolved so that it will be massively implemented in almost all markets like fingerprint scanner technology or high-resolution cameras.

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