When designing a wireless charging system, the key factors that affect the design are user experience, efficiency, power size, standard, component selection / availability and cost. A good design of the system can provide many benefits from improved features (such as smart mobile phone no longer need to plug) to support the new technology (such as in radioactive environment sensing concentrator, in this case not through wired charging, and man-machine interaction also is not safe) and so on. Wireless charging system using magnetic coupling technology from the late 00's nineteenth Century already appeared, but until recently, the latest progress of element chip and system architecture which makes engineers in their equipment to realize wireless charging system is practical to improve the user experience. Let's discuss the first five elements of a wireless charging design. 1: how users interact with the device is one of the most basic questions for every excellent engineer to ask at the start of a project. Do customers need to charge fast? Do you need flexibility in alignment? Does it require low calorific value? Do you need to charge a long distance? Do you need high power? Each transmitter needs more than one receiver? Do you need a small size? All of these options are satisfactory, but they usually need trade-offs. For example, high power and low calorific value are not always able to be met at the same time. Distance and efficiency are basically in the opposite direction. Therefore, it is a very important step to understand what the user needs and how to prioritize these needs when designing a wireless charging system for a certain device. 2: efficiency is always the first among the indicators used to measure the performance of a wireless charging system. A naturally efficient system provides far distance, better direction flexibility, lower fever, smaller size, and smaller power leakage current. The following are the three main modules of wireless charging system has a decisive effect on the efficiency of the three modules: Figure 1: wireless charging system if all three modules work in estimating the efficiency of the lowest (that is shown in the figure of 80%, 70% and 80%), the total efficiency of the system is approximately equal to 45%. For a 5W device, it is necessary to use 11W's transmit power to provide full speed charging, and about 6W dissipates in the device itself (as heat dissipates) and the surrounding environment, including air, devices and human tissues. In low power conditions, this may be safe and acceptable. But at higher power, such as the charging of electric vehicles, the typical charging power is at least 5kW at that time. Then 6kW is lost in the transmitter, vehicle and surrounding environment, so it will cause serious heating and safety problems. When all three modules of the wireless charging system work at the highest estimated efficiency (95%, 90%, and 95%), the total system efficiency is about 82%. In this case, a 5W device only needs the emitter to provide about 6W of the charging power, and only the 1W is lost because of the invalid. In order to improve the efficiency of the system, the designer should focus on the high efficiency components to improve the coupling between the transmitter and the receiver. 3: the power level uses a magnetic field coupled wireless charging system to charge a device from milliwatts to a kilowatt level. For milliwatt equipment, energy collection or radio frequency wireless power may be a more attractive charging scheme. The power requirements of the equipment will determine the selection of your components, the company that can be designed to cooperate with you, and the size of the equipment. 4: standards and regulations have many standards in the field of wireless charging for electronic devices, including wireless power alliance (A4WP), power incident Alliance (PMA) and wireless charging Alliance (WPC). The purpose of these standard organizations is to provide an interoperability platform between transmitter and receiver, and to provide guidance for product and component innovation to meet regulatory requirements. If your equipment requires interoperability (do users need to recharge at the airport or local cafe?) So your design should be around a certain standard. Generally speaking, A4WP provides the most technically advanced solution for loosely coupled system. WPC has the most commercialized tools and components, but it is a tightly coupled system. PMA is being merged with A4WP to provide "tightly coupled" technology for its sharing standards.