I can't stand conspiracy theorists such as Ron Paul, Michael Moore or al Qaeda. But there is a science behind mega corporate collusion.

How much do you want to bet that for the next 7 years we will keep on hearing that the Volvo or Volt is not ready due to battery problems, and then all of a sudden the mega corps will open the gates and you will have 15 brand choices of serial plugins with 60 mile ranges?

Now call me a CT - but it aint stickin.

Roy, 1000A ? hehe

Besides, assuming equal efficiency in the motors (wheel or regular), why should the wheel motor need more Amps? Power = Current * Voltage (lets say 400 v.). So the current required should be same, no matter what transmission or gear ratio you have (assuming constant torque and efficiency).

Besides 4 in-wheels will each require 1/4 of the current, and about 1m longer for the cable length (4m * 1/4).

So current is

60,000 / (4 * 400) = 38 Amps per motor in steady state level driving. Probably 3 times that for the peak.

I think you are thinking of 12 volt golf cart batteries in parallel maybe?

Ooops, the 60KW output is peak, so the 38 A per wheel is peak.

So for steady state medium-speed level driving it would be about 15 A. That is a 14 guage wire (same stuff you have in your house behind the walls or 10 guage for peak, at about 20 cents a foot, and about 250 grams a meter).

The engine & power-train folks will no doubt lose their jobs badly. Much easier to manufacture an in-hub electric motor in Nigeria than a 350 cid in Michigan. Any wonder why the big autos are dragging their foot?

What is going to happen to all the high-paid transmission folks? How about kick-scooter repair trade?

On the topic of generators for series hybrids, the “Linear Combustion Engine” seems very promising it’s been demonstrated at 50% efficiency (it converts mechanical energy directly into electrical energy at the cylinder level)… Hopefully they’ll be able to workout some of the kinks in the control system. Apparently Volvo is working on a version, so this could get very interesting.

Sources:
http://www.lceproject.org/en/principle/
http://peswiki.com/index.php/Directory:Linear_Combustion_Electromagnetic_Engines

@ AES -

You'd probably want to go with a Siemens-Rinia type engine, in which four separate Stirling cycles are linked in a ring topology because each of the double-acting pistons participates in two neighboring cycles. The desired phase difference between neighboring pistons is 90 degrees.

In the specific - and easiest - instance of a genset operated at constant speed and power, you would first use the linear alternators as motors to get the multiple free pistons moving with the desired phase differences, then precisely control the stator currents with PWM to maintain phasing. After all, in mechanical terms an electric machine is a damping element with either positive or negative coefficient. Each piston-alternator combo would also feature a spring that defines the natural frequency of the system. You end up with four coupled second-order differential equations, with non-linearities in the damping terms (gas dynamics + electromagnetic control).

It's not something I'm working on but based on what I've read about internal combustion free piston engines, I have a hunch this could be achieved with modern control systems. Not easy, mind you.

Of course, a crankshaft or wobble plate would be a substantially simpler way to synchronize the pistons. However, Stirling engines need a clean working medium (typically, hydrogen or helium) at high pressure to reliably deliver adequate power. External seals are a major headache, especially if they are on the hot side, so hermetically sealing the entire assembly is preferable. That leaves lubrication, though with true linear motion of the pistons solid lubricants on the piston rings may be good enough.

Another option - though perhaps more for stationary applications and modest temperature differentials (e.g. geothermal, industrial waste heat) - would be to replace the pistons with thin circular, concentrically corrugated plates (i.e. floppy in flexure). Even so, the diameter/stroke ratio would have to be high to reliably avoid metal fatigue. Also, the natural frequency of the mass-spring system tuned low enough to allow sufficient heat to be transferred in and out of the chambers in each cycle.

Mr. EE and JDT,

Yikes. Take a look at the data sheets (summary) given as a PDF file on the website you (Mr. EE) cited above (www.e-traction.com) and you'll see that the 60kW motor requires 300A continuous and 1000A peak. I'm talking about the ac current to drive the motors, not the dc input current you pseudo-calculated above, JDT. You've calculated the DC input current to the inverter. I say pseudo-calculated because 60kW is presumably the output power of the motor at the shaft, and you have to account for motor losses (roughly 5 to 10%) and inverter losses (roughly 5%) and probably fairly high 3-phase line losses if the inverter is located remotely from the motors, as is probably necessary for packaging.

My last lesson for you newbie engineers is "why would wheel motors need more current?" The simple answer is because wheel motors need more torque. Keep in mind I'm talking AC current, which is what the switches in the inverter need to process, and which is what drives their cost through the roof. Torque in the motor is the product of current and magnetic flux. Flux for most of these motors is established by permanent magnets, and the current is sourced from the battery/generator/cap bank by the inverter. The battery (DC) current is NOT of the same amplitude as the motor (AC) current! If you have a 10:1 gearbox, you need to produce about 220 Nm to get the necessary wheel torque (in my simplified sedan example above). If you don't have a gearbox, you need to produce 2200 Nm to get the wheel torque. So you need a larger airgap diameter AND higher airgap torque, hence more current, relative to a motor with a gearbox. This is why the wheel motors use an "inside out" approach - ie., magnets on the outside - to allow the largest possible airgap diameter while still being able to fit the overall diameter within the ID of the wheel assembly.

So, Mr. EE, don't laugh too loudly, and go back to your ac circuits/motors book and take a look. And JDT, no, I'm not talking about a 12V system. You should also be aware that citing a 400V battery is a best case situation, and you have to design for a worst case situation, which is when the battery is at a lower state of charge and hence lower voltage.

Best of luck with your EE career Mr. EE -- maybe you should consider an MBA 'cause you won't be hacking it for long as an EE.

Cheers,

Roy I laughed because I thought you were referring to the motors in the Volvo. I linked e-traction as proof wheel motors work but those were designed for heavy buses and trucks, I wasn’t suggesting you strap four of them to a Volvo (that would be insane). Anyways, the peak amperage for each of the motors in the Volvo is around 100A.

About the battery, the generator will turn on long before voltage drops below a preselected threshold. Even without that I’m not sure what you think might happen, power electronics have come a long way.

Thanks for the luck though. ; )

Ahem.  The specs for the SM350-1 (leftmost column) takes only 300 amps peak.  You'd only need 4 gauge cable to handle that.

Putting the PM armature on the outside is the mechanically optimal solution; you want the outside of the assembly to turn, not the inside.  You don't want it to weigh 85 kg, but nobody said this thing was the pinnacle of technology.

And yes, I am an EE.

@Engineer-Poet

Yeah, I think he was talking about the SM500/1 which is meant for large trucks and buses.

Just to be clear the Volvo ReCharge uses Hi-Pa wheel motors (Not e-tractions), most likely the 18kg version.

see them here:
http://www.pmlflightlink.com/motors/hipa_drive.html

Its amazing to see how fast an industry like the PC can introduce change and evolve the product compared to the auto industry. The car industry seems so slow its crazy.

One issue that I can see is the in the PC industry you have the potential for white box PC makers. Anyone can take a PC box of the shelf, pull the logic board and parts and make a working unit.

In cars, each car is a new package that needs to be tested, crashed, and then marketed.

Wouldn't it be great to have a common chassis - cabin, could be sold with minimal drive train. Then a cottage industry could be formed around competing over just energy storage and propulsion.

Like the Volvo c30 seems like a pretty nice starting point to me. Or maybe the Honda Fit. Let a lot of startups have a go at making the drive train. That might speed up progress here - and reduce market risk for the big car makers.

The issue here is not the drive train (although every bit helps). Without a battery solution, the electric car is like a submarine with screen doors. PHEV adds at least $7000 to the cost of the car and increases gas mileage from 45 (Prius) to 70-100 (estimated). That adds up to 300 gallons per year. Very few consumers will switch to this risk technology that requires a power outlet near parking spots.

We need BATTERY-LESS electric vehicles similar to the San Francisco buses, light rail or Personal Rapid Transit.

Forget to include references on battery technology progress and PHEV costs.

US senate testimony from Advanced Automotive Batteries on PHEV

Realist:

$250/KWh ESSUs are coming and should be mass produced by 2010-12. If so, the 150 mpg Prius IV PHEV-60 (Km) battery pack may cost around $2.5K.

By that time, according to CIBC Bank, Oil will be $150/barrel or $1.5+/liter or as much as $6/US gal.

It seems that time will change the equation rather quickly. Future PHEVs may not cost much more than current inefficient ICE vehicles, and even much less if the 10-year operation cost are used.

I dont know about you guys, but I am excited about the Aptera. (www.aptera.com) I already put a deposit on one. Its not the prettiest looking vehicle, but at 300mpg for the PHEV version it can't be beat.

I think the coming years are going to find an interesting assortment of innovation in several different directions. I think the true innovations are going to come farther down the line when all these new technologies merge. Aptera is using a capacitor system that charges the batteries in just a few seconds and allows the car to continue driving. Why not do that with a diesel engine? Diesel is several times more efficient than gas. If it works with gas, why not with diesel?

The series hybrid looks like a very smart approach the problem is that it results in very heavy and costly archictecture, the motors in wheels helps to improve the concept but still. I think the series hybrid architecture would work with a free piston engine type that simplifies and reduce the weight, but so far the autralian company who was working on this concept gave up, also the concept would make more sens with a diesel.

Anyway parallel or series the plug in is the futur no doubt about it, the barrier is still the cost and avaibility of the batteries. That's why the Aptera approach is ineresting, using a very light vehicle means smaller batteries then more affordable. Still a very long way before they sell a million vehicle like that.

I they developp Coal to Liquid solution massively they might keep the price of gaz around 3$ then this type of vehicle will not take off for antother 30years, sadly.

A lot depends on usage and perception. A town car would just get you to a close destination and back. For this, the EV would work. Commuting takes a lot of energy. Maybe we should live closer to where we work and/or telecommute more, but that is another topic.

U Wiscosin did this concept some 20 years ago
and 172 mpg on a converted general-morons GM Metro
and lead-acids. It was on display at one of the
earlier MREAs.

This is a much more refined version, no doubt,
but what took them so long ?

Plug in hybdrid is a nice concept but american people are fooling themselves if they think that it will keep them driving 5000 pounds SUVs and trucks for commuting at low price even with a gas price at 6$ a gallon (which will happen soon, no doubt about that), that is a dangerous illusion. First the electricity to recharge a PHEV is 80% from coal which is the dirtiest energy and generates a lot of green house gas. Second for a 5000pounds vehicle you need 20 or 25KWh batteries to drive 50 miles, I have no doubt that price of batteries will drop but it will be a long way before that such big batteries will be available at an affordable price.

In California, where many Hybrids are sold, the electrical generation mix includes nuclear, hydro, and gas, such that coal power is minimized.

We could build about 4 more Nukes in California and replace much of the fossil fuel generation, but the same wacko's that want to stop using coal, also do not want Yucca Mountain to open. And so we continue to burn coal like there was no tomorrow.

2009 is just around the corner and PHEV's should start showing up in the showrooms, with the Saturn Vue leading the charge.

Nationwide 50% of the electricity comes from coal. In California 50% comes from natural gas. Charging off peak, even in the summers makes sense and the power companies say that they can handle quite a bit of that. Think of the 3x nominal load on California summer days and now you can see that we might be able to take quite a few cars charging at night.

The question is: do you need in weel motor?at list for now. I think that we can do simpler cheper propoltion just using 2 or 4 off the shell electric motors with small shaft to the weel. The motors will sit on the main fram of the car

"for the next 7 years we will keep on hearing that the Volvo or Volt is not ready due to battery problems..."

You might want to take a look at the progress the LG Chem/CPI Battery is making - not temperature tested yet but it doesn't look like a... conspiracy.

http://www.gm-volt.com/

Let's have a cite:

http://www.eei.org/industry_issues/industry_overview_and_statistics/industry_statistics

I expect nuclear's contribution to double over the next 20 years at the expense of coal (add'l units will be built at current nuclear plants)

I bet Yucca never opens - high-level waste will simply be dry-casked on site.

@Ryan:
Diesel ICEs are 40% efficient at the crank at best; gasoline ICEs are about 25-30% at the crank. Both are minus about 15% less horsepower at the wheels.

ET AL:
The best use of in wheel motors I like to cite is in a Toyota Race Car: see: http://www.greencarcongress.com/2007/07/toyota-hybrid-r.html#more

All this stuff is doable; but, that nasty old profit motive and tied up investments keeps getting in the way of progress.

In any case, I believe recent breakthroughs in low-cost solar cells and battery technology point toward our future as quick-charged, long-range, light, efficient BEVs fueled by solar generated electricity.

see: http://www.motherearthnews.com/Alternative-Energy/2007-12-01/Solar-is-the-Solution.aspx

All the stuff and convolution going on right now in generating power and powering automobiles is all interim to the solar/battery solutions for personal transportation.