Standard QI for Wireless Charging
Smartphones, e-book reader and tablet devices already become our daily lives. However, those mobile devices must plugged into electric source for charging its battery. This method often cause problems. Ideally, once those mobile device placed in a container, battery soon recharged without having to use cables.
For those reason, more than 100 IT companies such as Sony and Panasonic join in Wireless Power Consortium. They develop standard to do wireless battery charging. This standard called Qi, that is taken from the Chinese, meaning the flow of energy. Its first version already set in 2010, but its implementation running slow. Since mid-2011, Verizon, Internet providers in United States, has been offering variety of smartphones with Qi support, including Samsung Galaxy. Furthermore this technology also used by Nokia in its flagship product, Lumia 920. While Lumia 820 already included a Qi-Charging Shell. Not only that, Nokia also offers charging station in the form of pad and loudspeaker.
Smartphone charged in one hour
Through Qi, a mobile device can be charged with maximum power of 5 watts. A tablet can be fully charged in a few hours and smartphones with smaller batteries usually only less than one hour. This new standards implements energy transfer per induction. Either transmitter nor receiver equipped with a coil. Transmitter coil which operated by AC current generates magnetic fields. When the receiver coil approached magnetic field, AC current also follow to be generated. Energy transfer lasted very efficient when transmitter coil connected optimal with magnetic field. Here, the diameter of coil determines the optimum distance between transmitter and receiver. Large transmitter coil that specified by Qi between 30 mm and 80 mm (depending on receiver model). While its distance around 1/10 from those value, which means the two devices will stack up each other. In order for electric transfer optimal, coil not only close to each other, but rather its location must also comply. According to Qi, magnet must be in center of transmitter coil in order to match with others coil in the receiver.
Communication through magnetic fields
Besides sending energy, magnetic fields also deliver information in the form of Bit and Byte. Communication between transmitter and receiver begins when the smartphone placed on a charging station. Furthermore, transmitter sends an impulse every 400 ms. If the voltage remains same, meaning no electricity that is sent. If the voltage decreased, means there’s a Qi-Receiver. Now, transmitter sends a stronger impulse to stir receiver. Receiver and transmitter communicating each other with Power Transfer Contract that informs the many of current that needed, the strong of current, and frequency of delivery. Furthermore, the transfer phase begins. Error control packets will be sent to transmitter to inform the receiver efficiency every 32 ms. If battery already full, receiver will send “End Power Transfer” packet so the transmitter will stop the transfer process.
Qi Development of version 1.1 in April 2012 has resulted in charging station that more better than its earlier version. With more coil per transmitter, mobile devices can be placed random in charging area. Electric will be sent by coil that has a better position. In addition, charging station with more transmitter means more devices can be connected simultaneously.
Unfortunately, not all manufacturers of mobile devices support this Qi breakthrough. Apple didn’t participate, while Samsung with Qualcomm developing its own standards. The plan, Intel will also offer wireless charging techniques that different on ultrabook. They prefer resonance compared to induction charging techniques. However, no definite information whether thosee technique compatible with standard Qi.