Is wireless fast charging technology really difficult? We can help you experience it in practice!
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This post was last edited by wangerxian on 2021-11-18 15:24
What is the principle of wireless charging?
First, let's define wireless charging: Wireless charging refers to a charging method that does not require a transmission cable to transmit electricity to the device like a traditional wired charger, but instead charges the device to be charged by contacting it with a wireless charging base. Wireless charging is also called inductive charging or contactless inductive charging.
Figure 1: Schematic diagram of wireless charging
The principle of wireless charging is electromagnetic induction, which is the physical phenomenon of the mutual conversion of electricity and magnetism under certain conditions. At present, the wireless charging base of mobile phones converts electricity into magnetic field, and the wireless charging coil on the mobile phone converts magnetism into electricity to replenish the power of the mobile phone. This is a complete wireless charging process for smartphones.
How is wireless fast charging achieved?
Working principle:
Wireless charging communication uses backscatter modulation, which is simply a load modulation method, similar to the principle of RFID. And the wireless charging process is mainly controlled by the Power Receiver (generally refers to the mobile phone), while the Power Transmitter (charging board) passively accepts requests and processes them.
A brief introduction to the wireless charging WPC communication sequence:
1) Place the mobile phone on the charging plate
2) The charging plate detects that an object is placed on the charging plate based on the change in the capacitance of the sending detection coil
3) The charging plate applies the power signal to the primary coil as a ping message and waits for a timeout. If the timeout occurs, it means that a foreign object is placed on the charging plate, and the charging plate cancels the power supply. This process is also called FOD, that is, foreign object detection; if there is no timeout, proceed to the next step
4) The mobile phone detects that the secondary coil has induced a voltage signal, and sends a Signal Strength message (the main content is the degree of coupling between the primary coil and the secondary coil, that is, whether the placement is correct)
5) The charging plate detects the Signal Strength message, cancels the timeout, enters the ID&Configuration stage, and waits for the mobile phone to send these two messages
6) The mobile phone sends an ID message (including VID and product serial number), and sends a Configuration message (mainly the maximum power Max Power=UI that the rectifier circuit needs to output)
7) The charging plate adjusts the corresponding parameters of the primary coil according to the received Configuration message, and adjusts the oscillation frequency of the primary coil to start sending normal power
8) During the charging process, the charging plate also receives messages such as Charge Status and Control Error sent by the mobile phone. For example, when the battery of the mobile phone is fully charged, the mobile phone sends a charging completion message, and the charging plate stops charging after receiving the message.
How to access the wireless fast charging module?
Recently, we contacted a professional charging technology manufacturer, which is very professional in wireless charging technology! It is Volta Semiconductor, which recently launched the third-generation SoC wireless charging solution, and it comes with an evaluation board!
Figure 2: Evaluation board overview
The wireless charger integrates PD fast charging protocol recognition function, 32K MTP, 9 GPIO and 11 ADC, and can be used for various customized applications. The input voltage supports up to 20V, and the output power can reach up to 30W. When fully loaded, it can be seen from the laboratory data in Figure 3 that when the receiving voltage is 13V, the output power gradually increases with the increase of current, and the efficiency can be as high as 85.3%.
Figure 3: 18W transmission efficiency
The temperature comparison chart in Figure 4 shows that when the power is 5W and 20W, the measured temperature of the chip is 29.9℃ and 36.7℃ respectively, maintaining the stability of the system. The lower temperature not only brings a good experience to customers, but also guarantees the quality and life of the product.
Figure 4: Temperature comparison chart
In sleep mode, the ultra-low quiescent current is less than 20uA, and it is equipped with a trigger-sensitive Auto Detection function. At the same time, it also provides good protection for device safety, input overvoltage, overcurrent, short circuit and overtemperature protection. Once an abnormality occurs, the power full bridge will automatically turn off the switch according to the configured action register, and the original Juggle protection (OJP) makes the system safer.
The evaluation board uses the NU170X chip, which complies with the WPC1.2.4 EPP protocol. The input voltage supports up to 20V and the output power supports up to 30W. It is a single-chip highly integrated wireless charging solution that supports dual-coil switching function and can be used for fully integrated single-coil wireless charging, vertical dual-coil wireless charging, magnetic wireless charging, and wireless charging mobile power supplies.
More information on the evaluation board: http://www.nuvoltatech.com/news/company_list/1110.html
Here comes the question! Are you interested in the above boards? If you are interested, from which angle should we evaluate them? Looking forward to the answer!
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