WPC New Standard ? V1.2.4 How To Pass It
- Apr 23, 2018 -

After the three new mobile phones in September 2017, the wireless charging has become a necessary functional option for the new mobile phone manufacturers in 2018. In March 27th, millet and HUAWEI chose to launch a new machine on the same day, in which millet was wirelessly loaded on MIX 2S, while HUAWEI chose wireless charging on the Porsche version of P20. In addition to mobile phones, two manufacturers have launched their own brand wireless charging transmitter. According to the latest data from WPC (Wireless Power Consortium), WPC has 512 members, more than 60 phones have been certified by Qi, and Qi - certified products, including transmitters (TX) and receivers (RX), have exceeded 1245.

This article will focus on the Qi certification of the current wireless charging industry and manufacturers, and detailed the authentication projects, processes and common problem points under the WPC new regulations.

WPC began implementing the new V1.2.4 Qi certification standard in March 2018. All the certified products are divided into two types: BPP (Baseline Power Profile) and EPP (Extended Power Profile) according to the load power. BPP covers products whose output power is less than or equal to 5W, and EPP includes products larger than 5W to 30W. Because EPP is a product authentication for the medium power (Medium Power), from the strict sense, all support Apple fast charging 7.5W and 10W Samsung fast charge SFC (Samsung Fast Charging) should be in the authentication category of EPP.

Whether BPP or EPP, the testing process of Qi certification contains two parts. The first is Compliance Test, and the second is Qi Interoperability Test.  The compliance testing laboratory ATL (Authorized Test Lab) currently has many choices in China. The compatibility test lab IOC (Interoperability Test Center) has only two worldwide, one in Belgium in Europe, and second in Korea.

For the wireless transmitter that is widely concerned, the testing process of Qi authentication is as follows:

1) conformance test. At least 5 prototypes are required to be sent by the sending tester, of which 1 will first arrange the compliance test, and the conformity test sample will remain in the ATL after the test is passed.

The main test contents include

Timing of communication protocol between transmitter and receiver

Test power output capability through translation of XYZ axis

Maximum supply capacity of energy transmission

Foreign object detection FOD (Foreign Object Detection)

2) compatibility test. After passing the conformance test, ATL will divide four other units of the prototype into two groups and send them to Belgium and South Korea's laboratories for compatibility testing. Two samples were left in the main IOC laboratory, and the remaining two left in the auxiliary IOC laboratory. The compatibility test will be carried out after the main IOC laboratory receives the samples sent by ATL. After the completion of the compatibility test, the inspection party can execute the "confirmation completion" action on the official network. The product can be included by the WPC official network, and the product will be left on the test bed (Test Bed). The current Test bed has about four hundred transmitters and one hundred receivers.

According to WPC requirements, all test samples need to be compatible with all previously certified samples. If the test product is a wireless charging transmitter, then it is necessary to do compatibility testing with all WPC Qi certified receivers.

Compatibility testing includes two aspects. First, when the transmitter and receiver are placed together, they need to establish communication within 3 seconds. Second, when testing battery power of 10% to 20%, it is necessary to maintain charging for five minutes.

According to the requirements of the WPC process, we need to be very careful in compatibility testing. According to the Qi test process, the product will be sent to the compatibility test after the compliance test is passed. If the compatibility test is not passed, the sample needs to be taken back and rectified. After the rectification, it can not be directly sent to the compatibility test, but needs to go through the conformity test + compatibility test process again.

According to the conventional test cycle, if a test product does not have any failure items, it will take 4-5 weeks to pass all testing items at once. According to WPC's data, with the 2017 certification peak in November as an example, a total of nearly 30% of the measured products failed to pass in the first compatibility test, while the EPP test sample was up to 61.5% for the first time failure rate; even the current BPP test, which is now widely used, still has close to 20% failure rates.

For such a high test failure rate, the author summarizes the most common problems:

1) during the work of the sample, the packet of CE (Control Error) jumped out of -1, 0, and +1.

2) the sample is interrupted by ASK or FSK before power transmission and power transmission.

3) FOD detection disorder

4) in the process of establishing the communication process, the transmitter and the receiver have a phase of the Qi protocol handshake, because the data package error causes the two parties to not be able to connect effectively.

5) the transmitter is very sensitive to the position of the receiver used in the test, and it can only support certain positions.

6) when the transmitter is sent to support a variety of fast charging protocols, such as 10W's Samsung fast charging SFC (Samsung Fast Charge) and the apple fast charging of 7.5W, the launcher is vulnerable to a protocol disorder during the Qi authentication test and can not work with the test receiver normally.

The author summarized the laboratory data in Shenzhen area, and combined with the problems listed above, the difficulties of wireless charging transmitter Qi authentication are focused on the following points:

1) twenty-third items (maximum energy supply test)

2) twenty-fifth items: FOD foreign body detection

3) compatibility tests are prone to fail projects with many receiver tests (to complete the two step test process after rectification).