How far is the car wireless charging?

- Sep 19, 2018-

In August of this year, the State Grid Key Technology Project “Development of Key Technologies and Equipment for Mobile Wireless Charging System for Electric Vehicles” and “Motor Vehicle Mobile Wireless Charging Experimental Section” passed the acceptance test, the first 100-meter electric vehicle mobile wireless charging in China. The experimental section was completed.


In fact, the new wireless charging method of "wireless charging" has already entered people's field of vision, but can such "black technology" really enter the public life?


Easy to use and remove


The basic principle of wireless charging is to realize the wireless transmission of energy by electromagnetic induction of an alternating electromagnetic field. “Without cables and plugs, the damage caused by the mechanical reasons of the charging equipment does not exist.” Guo Yanjie, an associate researcher at the Institute of Electrical Engineering, Chinese Academy of Sciences, said that the advantages of wireless charging are mainly reflected in three aspects –


■ High safety, no need to insert and remove the charging gun, and not affected by rain and snow and extreme environment;


■ High reliability, wireless charging has no mechanical wear compared to wired charging;


■ Convenient and convenient, it can realize automatic charging and solve the problem of the convenience of “last mile” of driverless driving.


As an electric car, the charging speed greatly affects the efficiency of people's use. So how does wireless charging perform in this regard? Guo Yanjie said that the charging speed mainly depends on two aspects, one is the car battery capacity, and the other is the charging power. At present, the maximum charging power that the wireless charging system can support reaches 3.3 kilowatts, which is the maximum power level that can be achieved by household charging.


In addition to power, another factor that affects wireless charging speed is external interference. Guo Yanjie said: In addition to the high power and strong electromagnetic field, the wireless charging device also uses the "magnetic coupling mechanism optimization design" technology, which can "lock firmly" the electromagnetic field when the car is charging, so that the electromagnetic field will not leak. To maximize the charging efficiency.


In fact, wireless charging is not a new technology. BYD applied for a patent for non-contact inductive chargers in 2005. In 2017, Maryland purchased a BYD pure electric bus with wireless charging technology. BMW officially announced recently that the 2018 530e iPerformance will be equipped with wireless charging system accessories.


Car companies admire wireless charging technology is inseparable from the support of suppliers. In 2015, ZTE and Yutong Bus jointly developed a 12-meter wireless charging pure electric bus, and completed the construction of a total of five wireless charging stations in Zhengzhou. The charging site can basically be unattended, and the charging process is fully automatic. The key starts and stops, the customer can remotely monitor the charging process through the mobile APP, and complete the metering and charging functions such as real-time recharge and payment.


According to a recent BMW document, the BMW Wireless Charging Kit includes an inductive charging base (charging base) that can be installed in a garage or outdoor parking space, and a vehicle component (vehicle induction coil) that is fixed to the bottom of the vehicle. The non-contact energy transfer between the charging substrate and the induction coil can be performed at a distance of about 8 cm. In addition, the BMW Wireless Charging System helps drivers find the right parking spot. The communication between the charging station and the vehicle can be connected wirelessly, and the vehicle and its surrounding top view will appear on the control display with colored lines to guide the driver during the parking process. The system will prompt you when it reaches the correct parking position of the inductive charging station. According to BMW, the parking position can currently vary up to 7 cm in the longitudinal direction and up to 14 cm in the lateral direction.


At present, some domestic car companies have also developed wireless charging cars. Perhaps soon, with the help of electromagnetic induction technology, electric cars can realize automatic wireless charging of parking lots, even charging while driving on the road.


Radiation problem leads to worry


Wireless charging In order to speed up the charging speed, it is necessary to increase the voltage and frequency, and it is inevitable to generate a high-power magnetic field. The radiation generated by the magnetic field has become one of the concerns.


"Radiation is not a worry, but a fact." Senior automotive electronics engineer Zhu Yulong said that similar to the principle of the induction cooker, if the wireless charging power is large, the generated magnetic field will have an impact on human health. He said that wireless charging power of 3 ~ 6kW may have a radiation impact on the human body, and the charging point is generally located in public places, individual users use wireless charging to consider whether the surrounding users can accept, if not handled properly may even cause disputes.


Research by the China Automotive Technology and Research Center shows that the measurement of magnetic field radiation generated by the wireless charging system at rest is lower than the standard public exposure limit of the World Health Organization. At present, China has also initiated the formulation of several national standards such as the General Requirements for Wireless Charging Systems for Electric Vehicles.


"With the development of technology, people's concerns about wireless charging have gradually eased. Before any technology enters the market, it will pass certain security and reliability verification, and it must be in compliance with relevant standards before it can enter the market. Regardless of whether it is domestic or international, the relevant standards for wireless charging have been included in the relevant agenda to ensure that relevant products are verified before market application.” Shujie, senior technical marketing manager of Qualcomm, said that wireless charging at home and abroad has also added foreign object detection devices. If someone or small animal is detected passing by the car during the charging process, or other foreign objects, the system will automatically power off to ensure absolute safety.


It is understood that BMW has explained the safety of wireless charging equipment: in addition to being installed in a garage, the charging substrate can also be installed outdoors and used in any weather conditions. All conductive components are protected against rain and snow, and the car will not cause any damage if it passes over the charging substrate. During the charging process, the range of ambient electromagnetic radiation is also limited to the chassis of the car. The charging substrate monitors the surrounding environment at any time, and the charging process is turned off whenever any foreign matter is found. BMW said that the charging process of electric vehicles in the future will be more convenient than the traditional internal combustion engine models.


In addition to electromagnetic radiation problems, wireless charging currently has a situation where charging standards are not uniform. "Different car sizes are different. For the same public charging point, the installation location of the car wireless charging device needs to be unified." Zhu Yulong said. However, the standards for wireless charging in the field of electric vehicles have not yet been introduced, and the manufacturers of wireless charging in various layouts are still fighting each other.


Popularity still needs time


According to reports, the current wireless charging technology of automobiles has been basically mature at the research and development level, but it is still in the application demonstration stage. It will take time for the public to go to the public. "In 5 years, a pure electric vehicle with a price of more than 300,000 yuan may have a basis for wireless charging. It is unlikely that a car with a price of about 100,000 yuan will be wirelessly charged."


Zhu Yulong believes that from a single technology point of view, wireless charging technology has not revolutionized the people's car experience. Even with the development of technology, the radiation interference is eliminated. The large-scale application of wireless charging cannot be in the short term. Implemented inside. "The current obstacle to large-scale applications is that wireless charging devices are more expensive than plug-in charging devices. Consumers hope that charging devices are not only simple to operate but also cost-effective. It is best to ship with cars like charging piles, but manufacturers should consider scale. Cost, need to be profitable. At the same time, the installation conditions are more demanding, and there will be various resistances in the installation. This is a problem that must be solved. It is understood that the construction of wireless charging roads and parking lots needs to be buried underground before the start of construction. Coils, for existing parking lots and roads, if you dig the ground to install the coil, the cost will be very high.


The industry generally believes that wireless charging technology has broad application prospects. Once successfully entered the market, it will greatly improve the convenience of charging and better improve the travel experience. At the beginning of this year, Zhejiang Province announced that it will build China's first super highway in 2022. The long-term goal includes the realization of mobile wireless charging.


Experts said that electric vehicles are not only vehicles, but also take into account the overall security and control of the infrastructure network, which is not achieved by the car companies themselves. Maybe in the future when the road is an electric car, the era of wireless charging will come.