The WPC is currently the largest wireless charging alliance

General steps for wireless charging
General wireless charging steps are divided into three stages: detection, communication and power supply.

(1) detection stage: identification of power supply equipment and foreign matter (FOD). When the receiver is placed within the working range of the emitter, the emitter 

detects whether a receiver is close.

(2) communication stage: identity authentication. The transmitter sends a packet and supplies power to the receiver to start the receiver, after which the receiver replies to the response data to complete the identity authentication.

(3) charging stage: power transmission. After identity authentication, the transmitter selects the corresponding power and other parameters according to the device type of the receiver to charge the receiver.

 To be sure, whether induction type or magnetic resonance type, the electric induction coil are alternating current (ac), because the us is the wireless charging, so the 

induction of an alternating current need for battery energy storage equipment for charging, charging requires direct current, so in the electric device by a rectifier and filter circuit, the alternating current (ac) rectifier and filter, after processing, the current can be used to recharge the batteries, this is a complete process of wireless charging.So from the above analysis, induction and magnetic resonance imaging, are both their respective advantages and have their own defects, in power distance, difficulty degree of system structure, system cost, product size and charging stations at the same time, charging power, frequency, efficiency, and no one can be fully met us at the request of the common to every scenario, wireless charging are still in a situation which may be embarrassing.

The above are the two main wireless charging methods. The following are three other wireless charging methods.

How to use wireless charging

So much for the theory, and now let‘s look at the application of wireless charging.The WPC is currently the largest wireless charging alliance with more than 200 members, including nokia, HTC, LG, SONY, samsung, qualcomm and, more recently, apple (whose wireless charging technology USES the Qi standard). The Qi specification, which was formulated and published in 2010, is currently the most widely used wireless charging standard, supporting more than 1300 kinds of products. The former A4WP members include qualcomm, samsung, Duracell Powermat, Intel, etc. The PMA is supported by starbucks, Google and AT&T. So these three standards are playing their roles and strengths in different areas.

However, it is gratifying to note that in addition to adding support for multi-device charging, the latest Qi 1.2 standard also includes magnetic resonance technology, which increases the charging power to 2000W. In the specification Q1.2.2, the magnetic induction frequency involved is 87 ~ 205KHz. The WPC chairman explained the changes to Qi‘s latest standard, which give low-power products greater spatial freedom, mainly vertical distance, and greater power. Therefore, Qi standard has been making efforts to overcome its shortcomings and better promote the application of wireless charging in a wider range of scenarios.