Principles and solutions of wireless charging (car charging)

In 2018 years, wireless charging has become very popular, and more and more OEMs have demand for wireless charging in vehicles. Want to enter this market, need a good plan. The solution platform introduced in this article, including hardware reference design, software routines, and Zhou Ligong’s complete technical support, can make your wireless car charger design simple

1. What is the Qi standard

Qi is one of the global standards for wireless charging equipment developed by the Wireless Power Consortium (WPC) wireless charging alliance. Currently, the Qi standard in WPC commercial promotion currently has 240 member companies, including TI, NXP, Microsoft, Panasonic, Apple, Samsung, Qualcomm, Haier, IKEA, etc.

2 Qi standard wireless charging principle

The basic principle of wireless charging using the Qi standard is not complicated. It is based on the two rules learned in middle school physics, namely

Ampere’s rule: an oscillating electric field produces an oscillating magnetic field;

Faraday’s rule: an oscillating magnetic field generates an oscillating electric field.

That is, the time-varying magnetic field generated by the power transmitter PTx generates an electromotive force in a properly positioned power receiver PRx.

When charging starts, the power transmitter PTx generates an alternating current through its coil, thereby generating an alternating magnetic field according to Faraday’s law. This magnetic field is picked up by the coil in the power receiver PRx and converted by the power converter back to a DC current that can be used to charge the battery.

A key feature of the magnetic field is that it can pass through any non-metallic and non-ferrous materials, such as plastic, glass, water, wood and air. In other words, no wires and connectors are required between the power transmitter PTx and the power receiver PRx, thereby realizing the wireless charging function.

三、car charging program

From the chips designed by upstream chip manufacturers, to the diversified products of various product companies; to terminal applications such as home furnishing and automobiles, the Qi standard complete ecological chain environment has been built together.