Will wireless charging colonise the cable market?
As any machine code performs the operation in its binary form of ‘0’ and ‘1’ or let's say as a ‘True’ or ‘False’ logic statement, the topic for today’s discussion is also somewhat like that and I would like to give my 2 cents opinion on wired chargers first as follows….
- With multiple digital devices in use today, Except if you’re particularly organized and good at tying down cables, chances are you have some dusty clutter around your house. You may even have had to follow a specific cord through the seemingly impossible tangle to the outlet, hoping that the plug you pull is the right one. While it can make people’s lives easier, it can add a lot of mess in the process.
- Personally sitting in my bedroom, I love having a long cable charger because it lets me scroll through Facebook while I watch TV. Basically, as long as you’re near an outlet, a wired charger means you can keep using your phone at the end of a long day.
Thus after reading the above points, I am sure you must be thinking then should we go for the wireless charging or not?
Well up to my research this is still a subjective topic and more advancements are yet to be made in this electronics business market so before getting to conclusions, let's discuss wireless technology first, its application usage with its pros & cons!
What is wireless charging exactly?
Wireless charging eliminates the cable typically required to charge cell phones, wireless devices, etc.
A wireless charger can charge the battery in any battery-powered device simply by placing the device near a wireless power transmitter or designated charging station.
As the name itself suggests wireless I would personally love to call this a clean energy concept. While the idea may sound futuristic, it’s not particularly new. Nicola Tesla proposed theories of wireless power transmission in the late 19th and early 20th centuries.
One of his most spectacular demonstrations was remotely turning on lights in the ground at his experimental station in Colorado Springs. For about years it was a technology without many practical applications, except perhaps for some models of electric toothbrushes.
Tesla’s work was impressive, but it did not immediately lead to widespread and practical wireless power transmission methods.
However, numerous wireless charging methods are available today, reducing the need for wires in everything from cell phones to smart wearables, laptops, home appliances and cars, as they offer the promise of greater mobility and advances that a small internet could make possible Things. (IoT) to get power many meters away from a charger.
Working Principle
At its core, modern wireless charging relies on the properties of magnetic fields and their ability to affect other magnet-sensitive things. The simplest example of this would be a magnet passed through a coil of wire, with the movement of the magnet creating a current in the wire that could be used to power a small lightbulb.
Inductive charging follows the same principle but goes much further.
The underlying principle of wireless charging is the well-known Faraday’s law of induced voltage, commonly used in motors and transformers.
- Inductive coupling uses magnetic fields that are a natural part of the current moving through the wire. Whenever an electric current moves through a wire, it creates a circular magnetic field around the wire.
- Bending the wire into a coil amplifies the magnetic field. The more loops the coil makes, the larger the field.
- When you place the second coil of wire in the magnetic field you create, the field can induce a current in the wire. This is essentially how a transformer works.
One can use the same principle to recharge several devices at once.
This might be too theoretical to interpret, let me illustrate to you by giving an example of charging a smartphone!
a) For convenience, there is one coil on the wireless charger and one coil on the receiver. So this is what happens when you place a smartphone that can charge wirelessly on a wireless charging pad.
b) The wireless charger emits a signal from its coil, which is picked up by the smartphone’s receiving coil. Once this happens, an LED on the wireless charger will usually light up or change colour to indicate that it’s charging.
c) A wireless charging pad has a coil, usually made of copper, that is tightly wound. This is used as the medium for power transmission from this wireless charger. When a current flows through the coil, it creates an alternating magnetic field.
d) A smartphone that can charge wirelessly has a copper coil receiver. This absorbs the alternating magnetic field and induces a current that is then conducted via a mains rectifier to charge the smartphone battery.
Construction Flow
Other than the transmitter and receiver coil there are some extra components which are responsible for the protection of the circuit with respect to charging are as follows:
- The wireless charging transmitter is powered from a 5V to 19V DC input rail, typically derived from a USB port or an AC/DC power adapter.
- A switched transistor bridge with two or four FETs drives an inductor and a capacitor in series. A resonant frequency is built up internally by means of the series capacitor.
- The transmitter has a coil to transmit energy by electromagnetic induction. Some transmitters support multiple coil assemblies driven by separate jumpers that are automatically selected to deliver the highest coupled power to the wireless power receiver.
- The receiver rectifies the current using diode rectifiers, usually made of FETs, to improve efficiency. It also filters the power with ceramic output capacitors and then applies it to the battery that needs charging, via either a linear stage or a switching regulator.
For Example :
Types of Wireless Charging
- Electromagnetic Induction (As shown above) :
A general wireless charging system with a simple, compact and inexpensive circuit structure that transmits electricity using the induced magnetic flux generated between the electricity sending and receiving sides. It is also characterized by its high efficiency. The disadvantages include the short transmission distance and susceptibility to misalignment. - Magnetic Resonance:
In this system, energy is transmitted by magnetic resonance using resonators on the transmitting and receiving sides. This method is generally used when a long transmission distance is required and is promoted for EV charger applications. However, efficiency is an issue. - Electric Field Coupling:
A transmission method is achieved by facing electrodes on the power transmission and reception sides to form a capacitor, utilizing the phenomenon that current flows between electrodes at high frequency (harmonic current). The transmission distance is short, similar to the electromagnetic induction method, but it is less prone to misalignment and less heat is generated in the power supply.
A disadvantage is the increased thickness of the high-voltage transformer. - Radio Reception:
This system converts electricity into electromagnetic waves on the transmitter side, receives the electromagnetic waves from an antenna on the receiver side, converts the waves into direct current using a rectifier circuit, and then transmits energy through an electromagnetic field. Although the transmission distance is relatively long (up to several meters), the efficiency is poor.
Wireless Charging Technology Standards
The main purpose behind creating any industry-standard is interoperability.
For example, any receiver with the Qi logo can be placed on any transmitter pad that displays a Qi logo. Perhaps even on a pad based on a different standard, provided the wireless receiver chip supports multi-standard interoperability.
- Three competing wireless charging standards have emerged in recent years, including Qi, PMA(Power Matters Alliance) and A4WP. The PMA and its Powermat inductive charging specification have been successfully testing their wireless charging technology in cafes and airports. In 2015, A4WP and PMA decided to join forces to form the AirFuel Alliance, which now has 110 members, including Dell, Duracell, Samsung and Qualcomm.
- All three are essentially based on Faraday’s law of induced voltage and use induction coils for wireless power transfer, but are tuned to operate at different frequencies with different control schemes.
- In traditional Chinese culture, qi (pronounced “chee”) is often translated as “natural energy.” It is also the name of the industry standard developed by the Wireless Power Consortium (WPC). Qi currently supports wireless power delivery of up to 5W over distances of up to 5mm but is rapidly expanding to deliver up to 15W and later up to 120W over much longer distances. The PMA and Qi standards are quite similar and are based on “magnetic induction principles”.They use entirely different methods of communication between the wireless power receiver and the transmitter.
- PMA reached an agreement with A4WP in 2015 to create a common standard (now Airfuel Alliance). This is based on a slightly different principle called “MR”, which stands for Magnetic Resonance Imaging. Early versions of the standard allowed power outputs of 3.5 W and 6.5 W, but lately, this has increased to 50 W.
Applications in Daily life
- Smartphones, tablets and wearable devices:
These applications typically require 2W to 15W of power. Multi-standard interoperability is preferred. Wireless charging can coexist with NFC (Near Field Communication) and Bluetooth, enabling very creative solutions. For example, paired phones can charge each other when placed next to each other after negotiating with the appropriate host and client.
- Accessories:
Headphones, wireless speakers, mice, keyboards and many other applications can benefit from wireless power transmission. Plugging charging cables into the tiny ports of increasingly smaller devices is an impediment to robust design. For example, Bluetooth headphones need to be sweat-resistant to survive in a gym environment. Only wireless charging can make this possibility possible.
- Public Access Terminal:
Deploying charging platforms in public areas requires systems to be safe and secure. Many coffee shops, airport kiosks and hotels support these scenarios. Furniture manufacturers are also designing discrete wireless power transmitters for their end tables and end tables.
- Automotive Applications:
A wireless charger is ideal for charging cell phones and key fobs by placing them on the dashboard or in the centre console of the car without cables going to the cigarette lighter. Because Bluetooth and Wi-Fi require authentication to connect phones to in-car electronics, the combination of NFC and wireless charging can allow the user to not only charge the phone but to automatically connect it to the car’s Wi-fi and Bluetooth networks without going through a specific setup.
- Electric Vehicles:
Smart charging stations for EVs (Electric Vehicles) are also emerging but require much higher power. Standards are under development.
Pros and Cons
Choosing between using a new wired or wireless charger comes down to what’s important to you. In simple words, as per my personal experience wired charging is about quick charging and wireless charging is about safety. In that case, I would like to discuss its cons first and then its pros..
Cons:
- Performance & Efficiency: If you value getting the maximum charge for your phone as quickly as possible, e.g. In those precious minutes between getting home from work and rushing out, stick with a wired charger.
Compared to traditional cable chargers, wireless charging is not as fast and efficient as cables. The energy losses due to energy transfer are also greater than with wired charging. Wireless chargers on the market are generally 15W. Wired charging is basically lossless, the charging power is generally 40–50 W of fast charging, and even a few manufacturers’ fast charging has exceeded 100 W. - Inconvenience: The other advantage of a wired charger is that you can use your phone for a long time while it is charging. You can move your smartphone through a limited range while charging. This is not possible with wireless charging. Your smartphone must be on the platform before it can be charged; If you move it from side to side, it will not charge. The device must always remain on the base.
- Cost: Compared to wired charging for mobile phone wireless charging, both the charging head and the mobile phone need to add a charging coil and related protection circuits. At the same time, a high-frequency wave circuit is required to meet electromagnetic compatibility, so the overall price is higher than that of traditional wired charging.
Pros:
- Compatibility: Wireless charging mobile phones on the market mainly use the principle of electromagnetic induction. There is no interface between the charger and the phone. No matter what brand of cell phone you buy, as long as it supports the wireless charging standard of the charging head, it can be charged in principle. If you’re at a friend’s house and he or she has a wireless charging pad, you can drop your phone to charge.
In wired charging, the Android generally uses the USB-C interface, and Apple has its own interface. - Durability: Because mobile phone wireless charging does not require frequent plugging and unplugging of the charging cable, the wear and tear of the mobile phone data interface are greatly reduced. At the same time, the mobile phone wireless charging coil is not exposed to the air, which can also reduce the oxidation and corrosion of the charger.
The risk of electric shock is greatly reduced compared to using a cord. Charging cables that have been used for a long time will wear out and may expose cables near the input head. - Multi-Device: One cable, one device. This is how conventional charging cables work. You cannot charge multiple devices at the same time. Wireless charging pads can charge multiple devices at the same time.
Miscellaneous
If I had to recommend one charger, I would still recommend a wired charger. It’s more versatile and almost always smaller, making it more convenient when you need to take it to work, school or when you travel.
Wireless charging is definitely worth it. It is convenient to use. But that doesn’t mean you should get rid of your charging cable. It sure needs some work. But there’s no denying that it’s certainly a nice feature.
Following this, I would like to highlight some myths about wireless charging!
Firstly, its low efficiency — Although the conversion of an electric current into an electromagnetic field and vice versa results in energy loss, wireless charging can transmit up to 80% of the input power. Much of the efficiency depends on the charging coil design, with good design and quality components resulting in less power loss. Cheap, non-certified wireless chargers tend to use inferior materials and components, and will likely fare poorly in terms of efficiency and reliability.
Lastly, overnight charging and frequently charging drain the battery — Almost, all types of charging will affect your phone’s battery in some way, as the percentage of original capacity that a battery can retain is reduced by about 20 per 500 charge cycles. For many people, the night is the best time to charge. Modern smartphone batteries have a built-in battery management system (BMS) that shuts off the battery’s charge capacity once it reaches 100%. No matter how long the phone stays on the charger, it stays disconnected from the charging current with no risk of overcharging. It is available in both wired and wireless.
If you have reached here, then I hope you must have surely enjoyed some insights into the wireless technology of our daily life!
Thank You!
Stay Safe!
Logging off at 3:00 AM IST !
