Electric Motors/Battery Power, etc. 1

[evelrod]

Let me preface this by saying that electric or battery power for cars is NOT my specialty. However I would be interested in the pros and cons of a "power wheel", ie a powered wheel where the motor provides motive power, regeneration and, braking in one unit. Given a computerized control system, this would seem to be an ideal way to power a small commuter type car or bike.
One drawback would be heat dissapation. What else?

 

[schiao]

Regen works great in an urban area as braking constantly occurs. Regen becomes less useful if the vehicle is driven on the freeway most of the time. For long milage range, hybrid should be considered. Whether it's powered by gasoline, diesel, natural gas, or fuel cell, it helps increase the range a vehicle can travel and definitely improves its efficiency. Electric or hybrid electric technologiies apply not only to small vehicles but as big as a class 8 truck, buses, or even tow tractors. A configuration in series works best for urban routes; a config in parallel works best for freeway routes.

 

[evelrod]

schiao---Thanks for the info, but what I really don't understand is how the regen can be as effective as it needs to be if braking is controlled by conventional means and not by the elect. motor in regen. I built a small elect. model car and used a rheostat to reverse polarity to the motor for braking. It was a bit clumsy, I'm not a great model builder, but it worked, albiet at the eventual cost of the motor. It died of overheat I think. Now , can this principal be applied to a full size auto? If so, how do we controll the heat without it becoming overly clumsy?

 

[schiao]

I cannot give you much info since it may become proprietary issues. But if you plan to throw ALL regen power back to motor, I could imagine your car may not brake smoothly. You need to sense your brake pedal electronically. You also need to monitor the load on your motor so you can have a system to decide how much regen can be taken. Energy storage pack like UltraCapacitor would be best suitable for regen as it's able to absorb/release power rapidly. For a primitive and simpler way, you may consider resistor bank for dissipating the excessive amount of energy. We (my company) use regen feature alot as many vehicles we build are buses which run in urban areas. Sorry I can not offer too many details. E-mail me if you would like to know some products my company offers.

 

[evelrod]

Definately. Send anything your allowed to give out. Especially in the area of brake modulation by micro-processer or electronically. Our tests, so far, show instability in braking as speed changes. My youngest will be back from Germany this summer (Army Sig. Corps) and he has ideas beyond my comprehension, so what else is new.
my email is roddav@msn.com

Since i'm 'kinda' slow on the uptake, anything at this point will help.

Thanks, Rod

 

[schiao]

I cannot describe any more details. Let me send you our company's info and you should contact our marketing manager.

 

[evelrod]

Thanks

 

[GregLocock]

An electric car typically accelerates at less than 0.1 g- 0.2 g. It needs to brake at the same rate as the surrounding traffic, 1 g . If you wish to rely on electric braking then the electronics and windings have to be designed to take currents 5-10 times the normal loads.

If you decide to forego the electric braking, or use a mechanical brake for serious braking, then a wheel motor seems to me to be an efficient solution. The proviso is that by its nature the windings will be fairly large, hence heavy, hence expensive.

Honda make a wheel motor for bicycles, which is a nice self contained unit, and is fairly efficient. I have only seen it in Japan. For my own electric bike I will be using a small high speed motor with a chain reduction.

Cheers

Greg Locock





Cheers

Greg Locock

 

[FireLover]

See my comments on post "current generation during regen braking".

One point is Safety is a big issue. A brake-by-wire system would never be used alone without some sort of a backup system. What happens if you lose power to the control module (it is only 1 wire)? NO BRAKES! There are regulations on this issue.

One question for Schiao: You mention hybrid and electric vehicle use in large trucks and busses, but they require lots of torque and power. Especially pulling a full load up a long grade! I would think that for large trucks and busses, electric drive systems would have a hard time providing the power relative to the typically used turbo diesel. You would need a lot of battery power to drive some high torque / high speed motors. I would think hybrids would be ok, but pure electric would be difficult. Any comments?

 

[schiao]

To FireLover,

You are totally correct. The only totally electric projects we have dealt with are vehicles like trams or short range delivery truck. Any other trucks/buses are hybrids.(fuel cells, diesel, gasoline, CNG, LPG,..., etc.) And all our vehicles do have air braking along with regen systems.