In fact, WiTricity is not the first company to develop wireless charging for cars. World-renowned automakers and related manufacturers, including Mercedes-Benz, BMW, Volvo and ZTE, have long been researching wireless charging for cars, and the technology has even been mass-produced in models such as the BMW 530e overseas.
Compared to the widespread use of charging stations both domestically and globally, the concept of wireless charging for pure electric vehicles may still be somewhat unfamiliar to Chinese users. Moreover, in terms of adoption, wireless charging for cars is only in its infancy. Given this, what is the significance of vigorously developing and even promoting wireless charging technology?
Let's first understand the current status of charging stations and wireless charging technology:
According to the first batch of charging equipment tender documents in 2018, the DC fast charging piles in my country are still mainly the 60kW version (accounting for 40%), while the charging piles with power of 100kW or more and 120kW each account for less than 30%. In addition, there are some AC slow charging piles with power of 7kW and 3.5kW.
In order to further shorten the charging time of pure electric vehicles, the development of high-power charging piles has become a global trend, including in my country.
For example, the first ultra-fast charging station of the European Fast Charging Alliance Ionity has been put into use, while my country has successively established 360kW high-power charging pile demonstration projects in Beijing and other places. At the same time, some buses have already used 350kW charging facilities. It can be said that the future of high-power charging piles is promising, but the limitations of charging piles themselves cannot be ignored:
1. Site issues: The construction of charging piles still requires "land acquisition", and related supporting facilities will also occupy a certain amount of land resources. Upgrading and transforming the existing charging pile distribution areas may be a feasible solution.
2. Unlike "current" charging piles, improving the output power of charging piles undoubtedly requires addressing both current and voltage. However, the relevant core hardware still needs to be imported, which places higher demands on safety and cost control.
3. Upgrading pure electric vehicles themselves: If they are to be compatible with high-power charging equipment, the relevant wiring inside the vehicle needs to have greater load-bearing capacity. At the same time, with the increase in charging power, the heat dissipation capacity of the power battery must also be strengthened. There are systemic difficulties in terms of technology, and reducing vehicle costs and selling prices is a "contradiction".
4. High-power charging equipment inevitably puts pressure on the urban power grid during operation, especially in areas with a high density of electric vehicles.
In contrast, consider wireless charging devices for cars:
While BMW will be the first automaker to launch wireless charging technology in China, its adoption remains quite limited, especially in the passenger car market. In short, wireless charging for cars currently has more symbolic than practical significance. For example, the overseas version of the BMW 530e Performance only has a wireless charging device with a power output of 3.2kW, which is closer to a slow charging station. This performance is acceptable for PHEV models, but it has significant limitations for pure electric vehicles.
Fortunately, some automakers have begun to promote the research and development of high-power wireless charging technology. For example, Volvo has invested in Momentum Dynamics and plans to apply high-power inductive charging technology to commercial electric vehicles and other fields. Thanks to the fact that the related supporting equipment can be "laid out" on the ground and there are no exposed connecting components (such as charging guns), wireless charging technology has certain advantages in terms of space utilization and reliability.
Portable charging – the killer feature of wireless charging
In 2017, Renault's all-electric van completed dynamic wireless charging tests in France, reaching a top speed of 100 km/h and a charging power of 20 kW on the test route.
Just last year, my country’s first mobile wireless charging test section for electric vehicles was completed and accepted. The charging power is 20kW, with an 80% conversion rate, and the magnetic field strength is far lower than the international standard of 27uT. The vehicle speed can exceed 60km/h.
However, the construction of wireless charging stations for cars may face high costs, coupled with difficulties in maintenance and installation. Even though the technology has obvious advantages, it is unrealistic to expect it to "replace" charging piles in every corner of the city.
"Standards" are also an unavoidable hurdle for wireless charging technology.
Taking the radiation issue, which is of utmost concern to everyone, as an example, according to the standards published by the World Health Organization, electric fields not exceeding 83V/m and magnetic fields not exceeding 27uT pose no harm to human health. However, my country's "Electromagnetic Environment Control Limits" (GB8702-2014) clearly states that the limits for electric and magnetic field strengths are 47V/m and 0.14uT, respectively, which are more stringent than international standards, thus laying the foundation for the development of wireless charging technology.
Therefore, in terms of addressing future travel needs and their own development, both traditional charging piles and wireless charging technology for cars will focus on shortening charging time. At the same time, each has its own pain points in terms of technology and cost. In other words, the actual gap between these two technologies may not be as large as we imagine, and they are more like "equal".
