How to Reach 200 MPH on Hydrogen Fuel Cells

the_manatee writes "Ford's 999 hydrogen-powered speedster is making waves for its upcoming speed record attempt in the Bonneville Salt Flats, but details on what's actually going on under the hood have been scarce. As it turns out, there are NASCAR-style brakes, steering, and suspension components, along with 16 Ballard Mk902 fuel cells that produce 350 kW of electricity. All that juice spins up a 770-hp motor and the rest is (hopefully) history. One final ingredient: 400 lbs of ice for cooling, which will melt in seconds once the car gets up to speed."

Re:AC?

[Cassini2]

Installing a motor in every wheel is intuitively a nice idea. Unfortunately, electric motors have a great deal of inertia. At high speeds, the effects of this rotational inertia dramatically affect the stability of the vehicle when it hits a bump.

At lower speeds, vehicle performance is maximized when the motors torque/speed curve is matched to the maximum speed of the vehicle while simultaneously matching motor diameter to wheel diameter. Unfortunately, the wheel diameter, tire diameter, motor diameter, and peak motor RPM rarely agree. Thus mechanical gearing often helps.

The effect of water vapor exhaust?

[tinrobot]

Here's a question...

The exhaust of a hydrogen car is mostly warm water vapor - the same output as a humidifier.

If the whole planet switched to hydrogen, what would be the overall effect of running a billion humidifiers on our roads? Would Arizona suddenly become as humid as Florida?

Re:Helium, Hydrogen...hey, it's all the same.

[br14n420]

Don't be so ignorant. You speak as if carbon fiber and other modern materials aren't even used. If you want an idea of what a "nascar style" brakes and suspension are like to purchase, a brake kit is just about $23,000. I'm actually interested in what you think the material differences are between a Nascar and a F1 brake, aside from differences related to the size of the wheels, as that is something that'll make an impact in both classes. The same goes with the engines. Just because a class is allowed take advantage of superchargers, turbos, compressed air, etc, doesn't mean it's any higher technology than a class that disallows these things. On both courses, you are building cars to run at peak horsepower for multiple hours. The limitation of these motors is a limitation of current technology, not any particular class. Anyway, if you think forced induction is high technology, you are getting close to a century off.

Re:AC?

[TheNetAvenger]

Installing a motor in every wheel is intuitively a nice idea

This was the subject of a few papers and subsequent articles in popular automotive and popular mechanics type magazines.

The conclusion was that technology would be needed to offset these effects and even at the time of the articles/papers 20years ago, it was not too farfetched.

With today's high response computers already in cars with active suspension, linear traction, etc. the computer technology to offset these problems is something that can easily be tuned using today's technology.

Some aspects of independent motors, or 'drive trains' to each wheel is 'enhanced' stability and traction control, as well as rotational tricks that would allow the car to rotate one wheel backwards while rotating the others forward. This would give a performance car incredible cornering, handling, as well as make available some interesting turning radius effects.

I can remember back when 'performance' car people hated the idea of 'alternative' energy or electric powered cars and saw them as the death of the sports/muscle cars. At the time I spoke up and tried to explain how wrong they were, as alternative technology could yield faster, better performing and safer sports cars. This is just one area and example of how new technology would achieve these results.

Re:"Brushless DC" vs "synchronous AC" motors.

[Cassini2]

For this application, they will be using an induction AC motor. This is not a synchronous AC motor. Induction motors eliminate the permanent magnets of Brushless DC motors and the rotating electromagnets of synchronous motors. Replacing the rotating magnets with a "squirrel cage" results in a small net weight savings, and a considerable inertia reduction.

In all likelihood the locomotives that you are talking about are also using induction motors. At locomotive power levels, induction motors allow for some nice tricks that blur the line between a conventional induction motor and a conventional synchronous motor. Specifically, if you have a separate power source / load for the inductive rotor, the resulting motor design looks like a synchronous motor, but is really a specialized induction motor. GE even has patents on this technology.

The power research group at my local university even did a research contract with a major multinational on how to exploit induction motor properties for use in new electric car designs. For weight sensitive applications (like a car) over 1 kW, almost all the motors are induction. Even for high-accuracy applications with servo capability, like CNC machines, all the large spindle motors are induction motors. With modern control electronics, an induction motor is all you need.

Re:"Brushless DC" vs "synchronous AC" motors.

[MooUK]

One point:
The point of maximum traction is actually the point when the wheels are just starting to slip. That's why the Class 66 (UK), amongst many others round the world, has traction control systems that at the lowest speeds allows the wheels to slip a quarter turn per revolution.

Seems counterintuitive, but it means one single locomotive can accelerate a train from rest - the difficult bit; once you're started it's easy to keep going - that without that technology would have been challenging for two or three.

Re:Power/Weight Density

[Agripa]

Before the advent of good silicon rectifiers, generators for cars used exactly this arrangement. The field was a separate winding and the field current was controlled by the regulator which monitored both the output current and voltage. Alternators of course have the field on the rotor connected through slip rings. Some model years during the transition had either system and you could tell the difference via visual inspection because the generators were narrower then the alternators.

AC motors do have power and efficiency advantages but what I was getting at in my original reply is that there is nothing inherent about a DC commutating motor which precludes regenerative breaking. The small market for high power DC motors limits the availability of a suitable controller.

I have seen some very large polyphase alternators that had a small DC generator on the same shaft to power their field winding where the field winding on the DC generator itself was controlled. The residual magnetism in the DC generator's stator was enough to bootstrap the system.