Match made in heaven - Automotive Electronics vs Wireless Charging

The origin of wireless charging

Electricity is a huge element that promoted the development of human civilization; it has great impact on people’s lives. Technology has always been developing towards more convenient, immediate and faster power supply. Since Nikola Tesla developed the Tesla Coil in the 19th century, the door to wireless charging technology has been opened. Today, wireless charging technology has been widely applied to electronic devices around us, such as mobile phones, wearable devices, electric toothbrushes and automotive electronics.

Since the first smartphone, the iPhone, was created, smartphone technologies have been developing rapidly, and the performances of smartphones have been increasing every year. However, the development speed of batteries has been a lot slower or even stagnant, compared to that of smartphones.

The stronger the performance, the more power is consumed, but when battery technologies could not keep up, it caused battery endurance to decline continuously for smartphones. Therefore, smartphone manufacturers started seeking the development of wireless charging technology, wishing to use more convenient charging to alleviate the problem of non-durable smartphone power.

Since smartphones have the feature of universality, when they started getting equipped with wireless charging technology, wireless charging also started developing rapidly in terms of popularity and technological capabilities. Now, approximately 10% and that is about 1 billion smartphones are equipped with wireless charging; the transmission efficiency with only 5 watts at first has also increased year after year to the high-power kilowatt level for electric vehicles now.

Principles of wireless charging

The wireless charging in our daily lives mainly uses the “magnetic effect of current” and “electromagnetic induction” to satisfy people’s need of convenient charging.

“Magnetic effect of current” - In 1819, the Danish scientist Hans Christian Oersted discovered that if power is connected to a piece of wire and there is current, a magnetic field will be generated around the wire and cause compasses to deflect. Scientists later further discovered that if the wire was made into a loop or even winding it into a coil, a stronger and more concentrated magnetic field will be generated. This is called the “magnetic effect of current.”

“Electromagnetic induction” - in 1831, the British physicist Michael Faraday discovered that when a magnet or other source of magnetic field gets close to a coil with no current, the coil generates “electromagnetic induction.” The establishment condition of electromagnetic induction is that the magnetic field must change, for example, the adjustment distance of the magnetic field. If the external magnetic field remains unchanged, no induced current will be generated.

In summary, wireless charging can be achieved using the two physical phenomena “magnetic effect of current,” where magnetic field is generated by the current flowing around and “electromagnetic induction,” where a continuously changing external magnetic field causes coils to generate electricity. Simply put, “electricity generates a magnetic force and a magnetic force generates electricity.”

Therefore, two types of correspondence are required to perform wireless charging: a charging stand and a charging device. The charging stand contains a tightly wound coil; when power is connected to the charging stand, a magnetic field is generated around the coil because of the “magnetic effect of current;” a charging device that needs to be charged is also needed (EX: smartphone or tablet) and the device also contains a tightly wound coil. When the charging device gets close to the charging stand, the magnetic field of the charging stand generates an induced current on the coil of the charging device because of “electromagnetic induction” and the induced current is conducted to the battery and this achieves the need of wireless charging.

It was mentioned above that the establishment condition of “electromagnetic induction” is that the magnetic field must change, such as the adjustment distance of the magnetic field. So when a charging device rests on a charging stand, in theory, “electromagnetic induction” should not be able to be established. Since electricity that is commonly used is an alternating current, the direction of the current changes continuously, and this causes the magnetic field generated from the “magnetic effect of current” to change continuously too, and this meets the establishment condition of “electromagnetic induction.”

There are still technical difficulties that need to be resolved for wireless charging generated through the “magnetic effect of current” and “electromagnetic induction.”

First is the charging distance; this is just like two magnets that attract one another: the farther they are apart, the smaller the attraction between them. Therefore, the distance of wireless charging on the market that meets the specifications are all very close; even the latest technology only allows them to be 4cm~5cm apart. Some wireless charging could not charge because of the thickness of the phone case, and requires removal of the case; this goes against the usage habit of the users.

In order to increase the distance and efficiency of wireless charging, the technology currently trying to be used to perform wireless charging is the principle of “magnetic resonance.”

“Resonance” - Objects have their own sound frequencies; when an object vibrates and makes sounds, objects nearby with the same sound frequency will also vibrate without being knocked. Such resonance also completes the transfer of energy.

“Magnetic resonance” generates resonance through “resonant circuits.” When special components such as capacitors and inductors are added to the circuit, a “resonant circuit” will be formed after proper connection. When power is connected to the resonant circuit, signals will be generated continuously in the circuit. When two resonant circuits with the same vibration frequency is placed together and one starts oscillating because power is connected, the other circuit will also start oscillating because of resonance and further generating current, achieving transfer of electricity through air. This can allow charging distance to increase up to several meters and improve charging efficiency.

Next is safety; since part of the energy loss from wireless charging will be converted into heat, if there are materials that easily conducts heat, such as a metal phone case, it will heat up more easily. In addition, metals have outstanding electromagnetic shielding properties, therefore non-metallic materials are mostly used for the back panels of mobile phones with wireless charging.

Applicability of wireless charging

“Ideal is full but reality is skinny” although wireless charging was introduced to smartphones for convenient charging, but when wireless charging is currently applied on smartphones, there are still realities that must be faced.

The wireless charging that general users expect should be like wifi where they can charge wherever they go and not have to place the device at specific places. Plus, the charging efficiency is lower than wired charging, so that the device must be placed at the same place and users have to wait for a long time. With wired charging, the device can still be used within the range of the cable while charging, but when smartphones are being charged wirelessly, the range is far more limited. Therefore, break time is required for wireless charging.

Also, a wireless charging device is rarely included when smartphones are purchased; users need to purchase them additionally. If multiple charging scenarios are considered, such as office, living room and bedroom etc., then multiple wireless charging devices need to be purchased. However, wireless charging can reduce the consumption from plugging and unplugging the charger and this somewhat reduces hidden costs.

In today’s life, wireless charging of mobile phones is not only for convenient charging, the use of wireless charging also matches the identity of technical nobility and being stylish. There are diverse wireless charging devices with high-tech styles and this has attracted many trendy young people to use them.

The applicability of wireless charging technology is still improving when applied on smartphones, but before smartphones entered the wireless charging field, wireless charging technology was already introduced to other 3C products because wireless charging has higher applicability in other 3C products.

For example, electric toothbrushes. Since they are in humid environments for long periods of time and they need to be waterproof and moisture-proof, wireless charging technology allowed the design of these 3C products that come in contact with water often to achieve high-strength integrated sealing, increase the beauty, quality, waterproof and dustproof grades of the product appearance and extend the durability of the product. The product features including low usage frequency and high placement charging time also match the features of wireless charging.

Even though it seems like there are many disadvantages when wireless charging is applied on smartphones, but when the usage scenario moves from home and office to driving and when wireless charging is changed to in-vehicle wireless charging, the applicability of wireless charging and automotive electronics increases significantly.

In-vehicle wireless charging vs daily wireless charging

Compared to 3C consumer electronic products, car needs face more complicated and extreme usage environments; not only from the hot Equator to cold Russia, they also need to face long-term vibrations and impact from mechanical impacts such as bumps, accelerations and emergency brakes during the vehicle driving process.

The usage life of in-vehicle wireless charging is also much longer than daily wireless charging. Since cars have longer usage periods and the in-vehicle wireless charging equipped by the original manufacturer is also included in the full car warranty, so the durability of the in-vehicle charging is also something that car manufacturers take into consideration.

Therefore, reliability tests of in-vehicle wireless charging include functional test, environmental test and mechanical test; there is also extreme environment test for high and low temperatures, as well as electrical performance test. It is much more rigorous than daily wireless charging.

The daily wireless charging scenarios are mostly in safe and stable states, so there is no need for large charging ranges and single-coil technology is used most of the time. But there is shaking and swaying during the vehicle driving process and drivers cannot be distracted for precise placement of charging devices; therefore considerations for the use of in-vehicle wireless charging not only adopted multi-coil and large charging range specifications, other common industrial designs include clip type, groove and cup holders etc. with LED appearances that can enhance the overall interior design quality of the vehicle.

In-vehicle wireless charging may affect the operations of some of the technologies in the car; for example, the keyless technology conflicts with wireless charging, causing interference to keyless and unable to start the vehicle. Keyless anti-interference technology can be added to the wireless charging board, it is compatible with the original designs of cars.

Not only is in-vehicle wireless charging more durable, safer and has human factor design, the feature of not being able to use mobile phones during the driving process matches the product features of low usage frequency and high placement charging time of wireless charging. Even if you want to use the mobile phone for navigation, related automotive electronic technology can be used to allow mobile phones to be in the two statuses, wireless charging and navigation, simultaneously.

(UniMax's Wireless Charger Pad for Car,WPC Qi Standard、FOD、Prevent interference Keyless Function.)

The equipment trend of major automotive manufacturers today is moving towards proving wireless charging; not only does this allow users to have fewer cables in the car and provide users with better driving environments, it also reduces hardware consumption from plugging and unplugging the charging socket and subsequent maintenance costs of the car factory and user.

The applicability of wireless charging with automotive electronics is very high.

Related applications of in-vehicle wireless charging

Compared to daily wireless charging, in-vehicle wireless charging can better integrate with high-tech technologies because of all the automotive electronics available.

Integrate high-tech technologies such as CAN bus, NFC connection and identification to the wireless charging board, and the charging status can be displayed on the dashboard and in-vehicle infotainment machine through CAN bus connection, allowing drivers to easily grasp the charging status during the driving process. Connecting NFC connection and identification allows users to achieve many applications through the NFC sensing on mobile phones.

In the past, cars needed to be paired with mobile phones through Bluetooth, which required many steps to complete; but when a mobile phone is being charged wirelessly, drivers can use the NFC sensing technology to allow the mobile phone to connect with the car through Bluetooth automatically while charging wirelessly, so the car stereo can be used to listen to music, radio or receive calls and messages from the mobile phone.

NFC sensing technology can also be used for the most important navigation function while driving; it can project the navigation content on the mobile phone to the in-vehicle infotainment machine to get bigger navigation screens. It can also project to the overhead display to perform turn-by-turn navigation so that drivers do not need to be distracted to look at the navigator; drivers can receive navigation information on the horizontal line of sight of the driver, providing drivers with safe, comfortable and high-tech driving environments.

The serial number of mobile phones is also used to identify the driver during NFC sensing to wake up wireless charging or personal vehicle settings.
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