When Honda isn’t working on hydrogen fuel cell technology to please the Japanese government, it occasionally finds time to work on electric car technology. In April, its engineers will present a paper at the SAE World Conference Experience that explores the advantages of dynamic charging systems for electric cars and trucks.
Dynamic charging is a concept that allows a vehicle driving on the highway to directly contact a source of electricity to not only move the car along but also charge the battery at the same time. It is an alternative to wireless charging systems that companies like WiTricity are developing for EVs.
In essence, the Honda people say if a car could be in physical contact with a charging source for one mile, it coulse pick up enough energy to drive 25 miles. That means only 4% of US highways would need to be electrified in order to meet the needs of EV drivers. Stopping to recharge batteries would become a thing of the past.
The Honda dynamic charging system would operate at high power levels. The system for cars would use 180 kilowatts of power — 600 volts AC at 300 amps. The system for heavy duty trucks would be far more powerful still at 400 kilowatts. Honda claims the system could work at speeds up to 96 miles per hour and cost just one twentieth what a nationwide wireless system would.
Wireless systems are getting pretty good, but they cannot begin to transmit as much power as a connected system. Most operate at 7.6 kilowatts with the hope that they can get to 15 kilowatts eventually. Clearly, the Honda system would be much more powerful than that.
But questions remain and until the paper is presented at the SAE conference, details are slim. To establish a direct connection, some component of the car would need to actually contact a power source. Think of the third rail system that subway cars use. They have a shoe that extends from one side and rides along an electrified rail.
That works OK in the confines of an underground subway, but keeping people and animals from electrocuting themselves is another matter entirely. That’s where an overhead wire contacted by a pantograph on the roof comes into play.
The abstract from the pending reports says, “Reducing the amount of CO2 emissions to zero while driving is considered an important goal for the mobility sector in order to achieve a zero CO2 society. A key point in achieving this is the further evolution of electrified vehicles that are driven only by motors and are not equipped with a generator that uses fossil fuels, that is to say electric vehicles (EV) and fuel cell vehicles (FCV).
“Major issues facing EV include range, charging (hassle, time, construction of infrastructure), and reduced driving performance due to increased vehicle weight. Technology enabling to both supply power and perform charging while driving (dynamic charging) is being researched and developed as a means of addressing issues such as those above.
“If the amount of energy that can be supplied while driving does not at least exceed the driving energy of the traveling vehicle, then battery charging cannot be performed, and the vehicle would also need to continuously travel in a restricted lane in the manner of a train. In addition, dynamic charging of large vehicles traveling intermixed with regular vehicles calls for power supply on the level of 400 kW.
“Against this background, this study developed a high-power dynamic charging system that uses high power to charge a traveling EV, with the goal of realizing an unlimited vehicle range. This enables complete energy refueling (charging) of a traveling EV in a short time and allows drivers to freely drive over the intended route after charging.
“This report describes a system that enables dynamic charging with a charging power of 180 kW (DC 600 V, 300 A) while driving at a vehicle speed of 155 km/h, presents the results of running tests, and discusses future prospects.”
Make of that what you will. Once we know more about the Honda proposal, we will share details with you.
Source: Inside EVs