Replies

You are thinking 1900s level technology. MIT and a number of other’s have come up with RF induction vs magnetic the two are apple to oranges. RF induction works over several tens of centimeters and in MIT’s case several meters indoors.

Tesla has licenced a patented RF version for it’s CYBERCAB they tested it at over 90% eff. Welcome to the 21st century.

That said half a mile at 30 mph which would be around avg bus speed on a city street. Would give 1 min over a half mile run. RF induction can do 500kw of power transfer met with 90+% eff using only the coil ddirectly under the bus coils really but only the ones directly under the receiver are turned on with microsecond precision there is no stray fields along the roadway and the receiver being in tight coupling would shield the bus above it. People with pace makers would be safe in it. That and RF induction is in the tens to hundreds of thousands of hertz the wavelength is too long to couple with a pacemakers small metal case.

So one min at 500kw is 500000 joules over 60 seconds. That’s 30 million joules, there is 3.6 MJ in a kWh so 8.33 kWh would be transferred each time a bus ran over it. The Tesla Semi hauling a 82,000lb load averages 1.7 kWh to the mile a bus is 30,000lb and not moving at freeway speeds where air drag is the primary drag source at 30 mph a bus would use 800 ish watt hours per mile. This would mean a bus would grab 10 miles worth of range while passing over that road section. Since this is for busses running shuttle services to and from that Olympic venue that makes sense as each time a bus arrives it gets 10 miles of charge of the other end of the run is 5 mile radius or less when it returns it picks up the round trip for the next run.

Bus drivers have to take mandatory breaks at the end of a period of time and also at each end of a run for time phasing. Having a charger at these end of run or break points would allow for 15 minute charges or what ever the phasing pause time is usually 5 min. In those cases you can put in 150 to 450 MJ @500kw RF induction. Or 41-125 kWh for the 5 min case it’s 51 miles of range well past what a bus will do between mandatory break stops or phasing stops the 15 break stop would add a days worth of range @188 miles well past what an urban bus would run on a route in a day. Only regional or maybe outer suburban busses would exceed 100 miles of total travel in a day.

So yeah a half mile section on a feeder route to a major event space where every bus entering and probably leaving would cross could make the whole thing differed emissions since you shifted the diesel particulate matter emissions ,NOX,SOX to gas turbines far outside the city not a bad switch since gas turbines are 60+% efficient in combined cycle plants, and they make zero SOX, near nero NOX, and zero particulate matter emissions. Even taking into account grid losses at 5% for 200 ish miles of HVAC and the transformers plus 10% for the induction loss and 8% more for the round trip pack loss. That still beats a diesel at 30% avg efficiency in commercial duty usually the BSFC of a bus is under 20% they get single digit mpg on diesel. All that stop go stop go is energy lost to heat via the brakes and running the diesel to accelerate inertial mads from a stop every stop is horribly inefficient. Electric motors have max torque at zero RPM and can recover deceleration energy as electrons back to the pack vs heat in brake pads this regen alone cuts in half the energy needed it’s why hybrids double the mpg of their ice cousins of the same size vehicle. A Corolla vs a Prius perfect example Corolla 30 mpg city , Prius I have seen 80mpg or more over ten miles of city traffic driving.

Here is Tesla wireless

https://www.teslarati.com/tesla-wireless-charging-efficiency-above-90/

You’re right, I retired from the auto industry in 2000 so any work I did on this came in the last century. Thanks for the update. I did work on the 2000 GMEV regenerative braking system, but not on its inductive chargers.

High frequency magnetic resonant technology is certainly a step in the right direction, but not yet a panacea. It still involves k, the magnetic coupling efficiency, and also the limitation on the battery charging rate limits. Super caps might help that but would then involve ANOTHER large set of hardware and circuits with efficiency losses. On the road, it would also require tunable resonators to match whatever is driving over them. The required high Q values for the circuits increases the difficulty of doing this.