Design Of Quick Chargingand Mobile Power Supply Based On USB_PD Protocol

With the arrival of the smart age,mobile phones,tablets and other portable electronic devices are increasingly developing towards smart and large-screen,which brings great convenience to people's life and communication,but at the same time,the frequency of use is also increasing.Lithium-ion batteries in the device can not provide enough endurance for the device.When you are out and the device is out of power,you can use the mobile power supply to change the device.With the rise of the mobile phone quick charge technology,the traditional mobile power began to quick charge mobile power development,the quick charging technology applied to traditional mobile power supply,greatly increasing the charging speed,shorten the lithium battery energy storage time,so the combination of quick charge technology and mobile power of research significance and application value.The main contents of this paper are as follows:First of all,fast charging technology is in the period of rapid development,all major manufacturers have launched the corresponding fast charging technology,but basically for their own product ecological chain service.In order to end the confusion in the fast charging technology market,the USB_IF organization launched the USB_PD protocol,aiming to unify the fast charging technology and realize the generalization of the fast charging technology.Moreover,the charging method of lithium battery in mobile power supply is studied,and the three-stage charging method which is more consistent with the characteristics of lithium battery is selected as the charging strategy to ensure the healthy use of lithium battery.Secondly,in order to improve the conversion efficiency of the system and meet the high power transmission demand of the system,the four-switch tube voltage lifting circuit which can work in a wide input voltage range is studied,and its three working modes are analyzed.Among them,how to realize smooth transition between working modes is an important research content of the circuit structure.This paper studies the conduction sequence of the switch tube in the lifting and lifting pressure transition mode and realizes the smooth transition between modes by judging the duty cycle.Finally,the hardware circuit structure is analyzed and designed.Taking the EDP3010 digital power management SoC(System on Chip)developed by the internship unit as the control core,the control software was written in its internal integrated microcontroller,and an experimental prototype was successfully built.The experimental results show that the quick charging mobile power supply based on USB_PD protocol achieves high power and quick charging and discharging functions.When quick charging mobile power supply through USB_PD protocol,the protocol power level that can support 20V/4.5A is the maximum,and the charging efficiency of each protocol power level is the lowest 93.6%,the highest 98.1%,and the maximum protocol level when discharging mobile power system The output is 20V/3.25 A,and the five power outputs have the lowest efficiency of 93.3% and the highest efficiency of 96.8%.In addition,the protocol compatibility of charging and discharging of quick-charging mobile power supply is tested.It can negotiate with other devices that also support the USB_PD protocol for power and conduct quick charging and discharging.Finally,the application of fast charging technology is realized,and the design scheme has the advantages of small peripheral device demand,high conversion efficiency and strong compatibility.