Now, wireless charging technology is no longer a new thing for the public. Unlimited charging has been applied on many mobile phones. But in the automotive sector, wireless charging is still rare. At present, only a few models such as BMW 550e and Roewe Marvel X support wireless charging.
There are many unique requirements for car wireless charging: because the electric car battery is large, the charging time requirement is as short as possible, so the charging system needs several kilowatts or even tens of kilowatts of power; the size of the charging coil should be as close as possible to the car, as light as possible; The spacing of charging is determined by the distance between the car and the ground. It is very different from the wireless charging of mobile phones. Because of the high efficiency of wired charging, wireless charging must achieve at least 85% efficiency, which is commercially meaningful.
With the promotion of electric vehicles, the advancement of power electronics and battery technology, wireless charging of automobiles has gradually attracted the attention of the public.
The radio can be transmitted and classified according to the distance of transmission. From far to near, it can be divided into five types: microwave, laser, ultrasonic, electric field coupling and magnetic field coupling. These technologies can be divided into two categories: far field and near field.
The far-field technology is more suitable for long-distance, low-efficiency power transmission; the near-field high-efficiency feature of the near-field technology makes it more suitable for short-range wireless transmission. If the car wireless charging is divided into two categories, it can be divided into static wireless charging and dynamic wireless charging, which can be considered as the difference between parking charging and driving charging.
If you stay in static wireless charging, compared with wired charging, its main advantage is convenience. Although the wireless transmission efficiency has reached a high level, it is still lower than wired charging.
Static wireless charging still has some problems to solve. For example, how to detect and eliminate foreign matter in the coils at both ends of the charge? If any metal parts fall into the leaves of the two coils, it may cause a fire. If there are living things like kittens and puppies, in two coils, high-power transmission will also pose a great security threat to animals.
Dynamic wireless charging does not have the above problems, but it is extremely costly to implement and requires extensive modification and maintenance of an entire road.
The lack of technical standards also limits the popularity of the technology. The establishment of automotive wireless charging technology standards is not only the work in the automotive field, but also the revision of the relevant domestic and international standards for electromagnetic management; in addition, it is necessary to report to the international electromagnetic institutions at the same time to ensure that radio waves in the relevant frequency bands are not subject to influences.
There is no definitive theory to indicate the extent to which electromagnetic radiation is harmful to the human body. But for the public, electromagnetic radiation itself is a "sensitive word", wireless charging can not be accepted by the public, it also needs to wait and see.
Car giants such as Toyota, Nissan, Honda, and BMW; suppliers such as Bosch, Qualcomm, Huawei, and ZTE have been promoting wireless charging. In addition to improving static charging technology and standards, and continuing to promote cost reduction; dynamic wireless charging also has great potential. Limited to cost, dynamic wireless charging is not much even for demonstration operation. At present, the operation of fixed lines, such as BRT, park unmanned logistics vehicles, and in-plant AGV, may be the first scenario for dynamic wireless charging.