In recent years, wireless charging or inductive charging has become a desirable technology, as people are keen to avoid the mobile chargers and power cables to recharge their mobile phones, laptops, iPods and digital cameras. Fujistu laboratories limited has declared the expansion of wireless recharge technology that permits the design of wireless charging systems based on the magnetic resonance that can immediately recharge various types of portable electronic devices.
Wireless charging is already available for low-power applications such as mobile phones and other devices. But high and medium-power applications are also being developed, and in future kitchen appliances may be wireless.
In recent years, gadgets are changing the way we live our lives. Especially when it comes to mobiles, we are now getting used to new features, programs and processing speed and the complete new ways of using them. However, the battery life is not keeping up the pace of mobile usage. Therefore, to compensate such a requirement, wireless charging is available to eliminate the problem of the lifeless battery. This technology is even better to replace chargers, USB cables and adapters. You don’t have to worry about labeling or recycling old chargers.
Wireless Charging Embraces Magnetic Resonance Technology
Wireless charging technology allows the designing of magnetic resonance technology based wireless charging systems that can concurrently recharge different types of convenient electronic devices. The two methods: magnetic resonance and electromagnetic induction are used most often for wireless charging.
In electromagnetic induction method, a magnetic flux is induced by the power transmitter links with receiver coils, and based on the electromotive force, the receiver coil does the useful work such as charging. This method is used in Cordless phones, with other apparatus. The drawbacks of using this method are that the method works over short distances only, and the power transmitter and receiver must be in close range to each other. So this method is effectively no different than using a charging station with a wired connection.
By dissimilarity, the magnetic resonance method is proposed in 2006. This method mainly uses a capacitor and a coil as a resonator. The electricity transmits at the magnetic resonance between the power transmitter and the receiver. This method can transmit electricity up to several meters. A single transmitter can power several receiving devices. By using this method, we can charge everything from handy electronics to electrical devices.
Wireless Charging System
Wireless Charging technology has been recognized as a very attractive solution to a wide range of applications because it easily replaces charging cables and power cords. This upcoming technology is being adopted for charging mobile phones and other gadgets. A number of mobile communication service suppliers in some countries offer wireless chargers for smart phones.
Wireless charging system’s block diagram is showed in the above figure. This system mainly consists of a transmitter and a receiver wherein the transmitter gives power to the receiver through the existing magnetic field around the coupled coils. This wireless charging system works in a closed loop. The receiver sends the messages to the transmitter through the modulated coils’ mutual field to the needs of the mobile device. At the primary side, the transmitter demodulates communication signals and regulates the system’s operating point consequently. The AC/DC wall adapter gives energy to the wireless power transfer system. At the secondary side, the coil voltage is rectified and controlled by the LDO regulator (low drop out voltage) and connected to the load via a load switch.
Wireless Charging Principle
Qi system is a wireless charging standard licensed system developed by the largest technology association in the wireless charging industry. With the support of 150 wireless power consortium member companies, such as wireless service providers, semiconductor companies, and most importantly the mobile phone manufacturers, the Q1 system is helping us to carry wireless charging of mobile devices into the mainstream.
Qi system consists of a flat charging pad and mobile phone equipped with a compatible receiver. When a mobile phone is placed on the top of the charging pad – through electromagnetic induction – the mobile is charged. Basically, an AC current passes through the coil in the charging pad, which produces a magnetic field that makes a voltage in the coil of the receiver, which can be directly used to charge the battery.
Qi system provides electrical power transfer up to 1.6 inches (4cm). The requirement of low power that exists today distributes up to 5 watts to receivers, which is enough for gadgets, smart phones and small mobile gadgets. The extension of the watt from 10 to 15 is in progress to permit fast charging of phones and consumer tablets. In development, there is a medium-power specification that will send up to 120 watts for charging larger devices such as power tools and laptop computers.
Types of wireless charging
There are two most important types of wireless charging: conductive and inductive.
Inductive chargers use an electromagnetic field to transfer energy into the mobile device. This type of charging includes an induction coil which is capable of receiving the wireless energy. On the other hand, the conductive charging works with direct electrical contact between a battery and a power source. Three years ago, a wild-charge pad from the Pure Energy Solutions, which was a conductive charging solution, was released. The conductive pads covered with conductive panels and connected with similar conductive materials such as power mat USA, radio shack and Duracell have since then been followed with their own wireless charging pads. On the other hand, inductive chargers have gained greater support from different manufacturers such as Samsung, LG, Motorola, RIM, etc.
Advantages of Wireless Charging
The principles of magnetic resonance and magnetic induction are based on similar principles involving magnetic fields and AC currents. The implementation of magnetic resonance offers several advantages including:
- Charging is possible through an obstacle between the charger and the receiver.
- Multiple gadgets on a charging pad can be charged at the same time.
- The association of A4WP or wireless power and Wi power: the first typical wireless charging was based on magnetic resonance. Wi power was approved in January 2013, but was available in the late 2014.
- The wireless power consortium is also working on Qi obedient magnetic resonance technology to allow longer range charging.
Thus, challenging wireless charging approaches have until now maintained an exclusive identity, but differences reduce as we move on to the next generation products. However, In the near future, Fujitsu laboratories is going to continue this design technology in the development and research on wireless charging systems for mobile phones and other handy devices. This company is also looking forward to applying the results of this work to the field, including computer chips, power transmission between circuit boards and mobile charging for electric cars.