WiTricity
The Next Wireless Revolution: Electric Vehicle (EV) Wireless Charging – Power and Efficiency
The power and efficiency of wireless EV charging — and the future of electrified, shared, and autonomous transportation.
Imagine never having to think about fueling your car. That day is close at hand.
In such a world, cars charge themselves. The vehicle just gets the power it needs on its own, delivered wirelessly. There are no plugs or power cords, let alone trips to a gas or charging station. Fast, safe, and efficient wireless EV charging — an essential component of electric and autonomous transportation — is a technology that’s proven and ready to be deployed.
The Speed and Efficiency of Wireless EV Charging
Electric vehicles are extending their range and market penetration every year. According to the U.S. Department of Energy, EV range has increased by 56% from 2011 to 2017. Meanwhile, regulations are helping drive EV adoption — along with a rapidly increasing consumer demand.
In California, whose regulations set the standard for U.S. automakers, the state’s Zero Emission Vehicle program mandates 8% of new cars sold by 2025 to be EVs. By at least one estimate, the state is already nearly halfway to this goal. Moreover, Norway (2025), Germany (2030), India (2030), France (2040), and Britain (2040) have all mandated the complete transition from fossil fuel combustion vehicles to electrified vehicles.
In all, the future of personal transportation will increasingly be built around the EV, which means being more and more reliant on EV charging.
Consumers who buy EVs today typically buy plug-in charging stations for their home or office. Most, however, do not realize that the time it takes to fully recharge will be the same with either a wired or wireless charger.
Most consumer plug-in EV chargers — whether Level 1 or Level 2 (see sidebar) — operate in the 88% to 95% efficiency range. Leading wireless EV charging technologies today operate in the upper end of that same range — at between 90% to 93% efficiency.
WiTricity wireless charging is based on an improvement upon the physical principle of electromagnetic induction. Induction has long been used in household appliances like induction cooktops, charging electric toothbrushes, and even some smartphones.
Yet, the remarkable fact that Electric Vehicle wireless charging can be as efficient as plugging in stems not from induction alone. One additional technological layer is needed: the innovation of magnetic resonance.
In 2007 a group from MIT published the results of an experiment demonstrating that the use of magnetic resonance enables efficient wireless power transfer across mid-range distances. Using coupled magnetic resonators they powered a 60 Watt lightbulb over a distance of 2 meters, a result that received worldwide attention.
By tuning both the transmitter and receiver to an equivalent resonant frequency, the system becomes significantly more efficient while also allowing for transmission distances that are far more practical than traditional induction permits.
