Inductive Power Transfer - What Are the Possibilities for the Automotive Industry?

Your decimal point locator is broken.

I think you summed it all pretty well. Impractical and outta sight costs.

But at least if you are going to talk about inductive charging by the MIT folks, you should at least mention the efforts of the MIT spin-off, WiTricity.

http://www.witricity.com

For a vehicle charging application, in a stationary position, with highly resonant, tuned coupling between the transmit and receive coils, they are achieving a claimed 90% efficiency. This is at a separation of about 6 inches (15-20 cm).

There will not be a revolution in transportation. It will be a slow evolution as available resources change, technologies are developed, and people slowly adapt to our ever changing world.

Please be patient, we'll get there.

Cheers !

I wonder how such a bunch of nonsense can be published. Your 6 inches looks a bit like what is possible. Can you imagine a car driving between obstacles for hours within this distance? And the car is moving. At a speed of say 60 MPH, there is not 1 % left of the good intentions. Technology brought some renovations for HF chopping with IGBT's.

So that we do not have to depend on HF power amplifiers. Iron in the inductors will work like electromagnets, so is that an option? Perhaps we need pulsing waves like an MRI ? New sounds will be announced then too. G.A.

If all were that easy, electric cars in extremis need no batteries at all?

Is this contagious? Are they going to leave the microwave ovens open? UTOPIA. is the place. Sorry SF

ninety seven percent is very good. I would expect that if your bus stopped and let down a secondary onto the primary transformer pad. Won't happen if it is running on the road. But of course, in many places, you still have overhead electrical wires designed for those busses. The advantages of battery supported electric vehicles are many. You could have overhead wires outside of the tourist parts of the city, just as a for instance. However.... that old bug bear... efficiency. Batteries suck for efficiency. But, perhaps they have their place. Perhaps inserted strips of primary transformer would be more efficient than charging batteries... Intuitively, I think so. I may be wrong. Either way...it would be more efficient and nicer to have around than a diesel bus.

Would be nice to get the cars and diesel busses out of Naples and Florence. (Just two of many cities which I love dearly but are being ruined by motor cars) But thats not gonna happen until they get good public transit. Moving sidewalks come to mind....

If I can't have moving sidewalks, I would settle for trams...

In Italy, wireless charging is used with passengers on board, with assurances that it's safe, but this is obviously a concern if you start applying it at scale across highways and fast moving vehicles. What are the effects of the lost energy? Is it purely heat, or also radiation?

But is it really safe? What about metallic implants (artificial joints, etc)? What about pace makers? What about our electronic gadgets?

What happens when the road is repaved?

The use of Electric cars is very attractive but the costs and infrastructure- plus the recharge ability make it impractacle in the forseeable future.

As we have been told countless times fossil fuels will run out and they also also pollute,

However fuels from hydrocarbons can be utilized to create ethanol, and while it would appear the major fossil fuel companies are doing their best to disparage these by sourcing ethanol only from usage of food and feed stocks and confusing the issue- it is a fact that fuel ethanol can be made from grass cuttings, leaves and other normal waste home and farm products and the technology is there to convert these easily, and also and produce engines that can use these fuels better-and lower emissions, but again we see major Oil dragging their feet as they cannot get income from these waste substance material usages, and they can and do exert significant pressure on Government to downplay use of products that cut into their income stream

I think the processes for making ethanol from cellulose suffer from high cost/low efficiency currently, lower than corn based ethanol, which some claim takes more gasoline/diesel to produce than the result could possibly offset. Even after problem is surmounted, just because a crop is grown for cellulose instead of starch, does not mean it isn't competing with food and other things necessary for human life (like shelter).

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Sure there is an amount of waste that can be utilized (and should help a certain amount be price competitive early on). Paper plant waste is a good example.

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I don't think yard clippings are a good example. The ritualistic cutting of the lawn should be done away with. I doubt the amount of grass clippings harvested could yield anywhere near the amount of ethanol required to power the lawn mower and conversion processes.

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If a farmer wasn't growing switchgrass, that farmer and his implements might be producing food. If timber is being used to produce ethanol, it isn't available to put roofs over heads.

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There are opportunity costs for each undertaking....even for cellulose based ethanol.

any step foreward would help- I am not advocating we immediately convert to cellulose ethanol, but if we make a start hopefully in the not too distant future we could be on a track that would help- every thing must start somewhere and the sooner we start the sooner the possibiliy of success- and re the comment about priority of crops over fallow- In our area there are more fallow fields than productive- so obviously the local farmers do not have crop sales to justify full usage-

The people who believe that cell phones are giving them brain cancer are bound to go absolutely simian-feces if this technology is ever widely implemented.

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3% to 10% of 10kW originating just a few feet below their balls, must achieve power densities several orders of magnitude greater than making a cell call.

Inductive Power transfer - what are the possibilities?

I think it may be possible that exposure to the rate changing field could be limited through materials and design.

The biggest challenges would be meeting the power transfer requirements to cruise at 70 MPH while charging. That's a lot of power. Can that much induction can be made to occur between the charging cables just below the surface of the road way and the collector mounted on the bottom of the vehicle.

How could the challenges of snow, rain, temperature extremes, and power transforming from the grid to the charging cables be met?

It seems intuitive that the field densities required would vary inversely as the acceptance of the collecting circuit in the automobile. Would super conduction have an application here?

I think its a cooooool idea - but man - the engineering challenges!!! And the throughput efficiencies using the grid is probably down in the pits when compared to an onboard ICE prime mover.

You won't lose power to the air by expanding the gap...you only lose the ability to move it from primary to secondary. Like...you can only get seventy percent of the energy to the moving vehicle, the other thirty percent is simply not transmitted. (wrong word I know, but that is what it does.)

If you can use seventy percent you are golden. That thirty percent is not lost...so the efficiency is still at near 100%, any losses after that are normal copper and iron losses. (reluctance)

Or am I wrong about this? Set me straight if I am...

I tend to agree with you that, in the more likely real world implementations, the largest contributor to inefficiency will probably be copper losses and perhaps iron losses.

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I think the question of losses to transmission is highly dependent on the frequency utilized. There is also the question of losses from material near or traveling on the road that is ferromagnetic or is a good conductor of electricity.

I believe the process throughput efficiency will be somewhat less than the product of the power plant generation efficiency and the transmission efficiency factors. Pulling numbers from you know where brings me to less than 20% at the induction cable.

Thermal power plants are not very efficient and the centralized grid system only adds to the inefficiency.

Again; an ICE/Electric Regenerative Capable Hybrid will be much more efficient than a grid powered system.

Guessing at 35 hp to cruise at 70 + a 1kw charging rate would require an induction power transfer rate of about 27 KW. That's a huge amount of power to be sending through such a wide air gap - especially one that has suspended water droplets, snow, dust, and whatever else gets kicked up.

If charging on the move is desired then perhaps looking at a low voltage contact cable down the center line of one lane; with stored energy used to pass.

But again; any electric vehicle with a thermal power plant as the source of charging is already behind the efficiency eight ball.

Well...this is what I meant by difficulty to define "efficiency". Copper losses and iron losses, and transmission losses down the wires really do cut into efficiency. How can anybody argue that! I just questioned the "air gap" loss. I don't think it is a "loss" at all... just an inability to get the power from one side to the other. If there is no secondary coil...then there should be nearly no losses, any of which can be measured as "heat to the air". If there is a secondary sitting on the pad, then there are transmission losses...which me may be happy to accept as long as they are under a few percents.

If there is an air gap, then the size of the air gap becomes important. The higher the air gap, the less power you can get from primary to secondary. But that doesn't mean that if you went down to say, 50%, whatever, the remaining 50% would burn off as heat to the air. It is "heat to the air" which I always mean when I talk about efficiency. I note that many CR4 members tend to throw around that word "efficiency" in a different way. Usually causing confusion between effective transmission and heat to the air.

I hope that helps....

I see all the above responses all addressing a centralized electic grid but all seem to agree- however periferally, it is hugely costly and subject to many problems that need solving- so why are these very wise people wasting time beating a horse that wont run without a shock start- lets look for viable alternatives- renewable , non polluting and easily producable- surely we have the brains and technology to find it

I read Tom Blees' Prescription for the Planet some time ago, so I hope my memory is sort-of accurate. (It is available online, free I think, if others want to get it.)

In it he mentioned a propulsion system for cars; I think it was based on the element boron. It seemed like science fiction to me, but we need visionaries to start these things. This might be the alternate we are seeking.

This topic was to explore public transit that runs off of electricity. Are there problems? Of course. Is there going to be enough electricity in time? Unlikely. Are engineers working on it? Well YOU are not...but many are!

Personally...

I want moving sidewalks. But noooooo body can see the point. Too expensive. Too new. Too different... too many obvious problems.

Until you are in a suv in gridlock. Then you start to wonder!

I am not talking about Heinlein's The Roads Must Roll. I am talking smaller stuff. Stuff that has a chance of working.

Oh well...of to my next pipe dream....

'....I want moving sidewalks. But noooooo body can see the point. Too expensive. Too new.....'

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New? Perhaps on geologic time scales. Physical examples of working moving sidewalks have been around for 120 years. Numerous examples exist worldwide. Surely even Canada must have some in the airports. I know you guys have airports, I've been to one.

Yusef1,

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I can only speak for myself, but I am not concerned about losses due to heating air in the gap.

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I do think that as the gap widens the potential for currents to be induced in places other than the intended coil would increase.

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Consider wheels. Most wheels are a large mass of conductive material....in the form of essentially one big loop no less. The lowest part of a wheel on many vehicles is often separated from the road by less than 6 inches. Think there might be losses to current induced in the wheels?

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There is a big difference in introducing a technology that can be seamlessly integrated into the current system, and one which requires new exclusive infrastructure....such as road on which only cars without metal (or probably even carbon fiber) wheel are allowed. Once we are to the point of buiding entirely new infrastructure, then you might as well put those vehicles on rails (for efficiency) and then your induction problem could go away as well.

People seem to think that an increasing air gap would cause a massive loss of energy... I have had people say it would use up more energy than the original transfer. I don't think so.. but then I am not a scientist. I think it just makes the transfer less. Less efficient... no. A lower amount gets transfered when you lift up and drive off... I believe that is what would happen.

As far as other things like you mention in your very excellent post consider odd thinks like bolts, screws, nails, all gathering in a place where cars can drive over them. What would a car accident above a induction pad do? How would you prevent electrical theft, for instance. Would you want to? Lay your I-phone on the pad. If it doesn't get run over, you got your phone charged!

How about floods? Rain? Snow plowing?

Engineers would have work until the end of the century!

I would think that a little processor on each pad would be needed to "turn it off" when it doesn't see a matching induction pad.

To put a figure on efficiency, it is only what gets to your car battery that counts. Through the air it would be miserably low. We have done that with audio signals in musea, that were captured by a headphone system that got its energy and audio oou of a (non battery powered) trimmed LC receiver. There were 4 carriers, each in a different language.

The system worked, but got replaced after less than 6 months with regular powered receivers and head (ear) phones, because of poor transmission volume.

The first phones were disposable crystal earphones with very low consumption. Transformers have efficiency over 90 % range, but work without a air gap and have iron as magnetic medium. Just do a test and let a coil 'induce' or radiate its energy in a second one through the air.

It doesn't work too well. Otherwise receivers should not have pre- amplifiers and amplifiers built in. (and the energy is only a fraction of a fraction).

As long as it doesn't turn into a fire hose of expensive energy blowing off into the air. They claim seventy percent. I don't care if it is ten percent... So long as you get enough to keep the motors rolling. Efficientcy...take it as given it won't transmit as much when the vehicle is moving compared to when it is parked. Design for it.

What about 0.01%?