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Saturday, July 28, 2012

A plug in hybrid with wheel motors on the rear wheels

Well while incessantly searching for news to write about for you, I ran across this video about a plug in hybrid equipped with wheel motors:
Video is courtesy of MTSU

To be fair to the inventors of this technology, it is known as a retrofit kit. Meaning it should be adaptable to about every car out there. But Dr. Charles Perry is rather hesitant to say all, he just says something like 'nearly all cars'.

This invention that I am sure he probably shares with MTSU (Middle Tennessee State University) as well as his past partner in such endeavors, Paul Martin, who Perry says went to work in industry, but does not specify what type of industry.

They have apparently solved the problem with wheel motors, i.e. the problems with them breaking off. But the important thing to note is that this technology was developed with city driving in mind. I am guessing after you reach over 45 mph, the hybrid system becomes invisible to the car. Not really a big deal, but this is a huge step in the way of EVs goes, and perhaps we will see someone develop this further into a totally electric car.

Now I would like to take a moment to discuss horsepower and torque with you all. The first and perhaps the most important point to make about torque is that all electric motors, unless they are equipped with a variable frequency drive, develop 100% of their torque when you energize the motor. Furthermore, it maintains 100% torque up until it reaches its peak, then it falls off. Perhaps this visual will help you to understand the idea better:
photo of torque curves courtesy of
As can be seen by this graph the torque does not begin to fall off for 'tq-1, tq-2, and tq-3' until approximately 590 or so. This graph does not specify what this measurement is of, i.e. nm, or ft-lbs! But you get the general idea. But horsepower is a function of said torque; specifically horsepower can be found by the formula: hp=(torque*rpm)/5252. Perhaps this image will make all of this a bit more clear for you:
image courtesy of netgain, and it shows the torque curve for a dual netgain 9 drive

So if we apply what Dr Perry says in the video (it is not real clear from the implications of what he says, for instance does the 200 ft-lbs of torque get produced by each motor individually, or is it 100 ft-lbs of torque per motor) at any rate we will assume that it is the latter and use the 200 ft-lbs of torque for our calculations, and 3600 rpms: hp=(200 ft-lbs*3600 rpm)/5252 which equals roughly 137 hp. Pretty good I would say, but we have 'guesstimated' quite a few things here, but again you get the general idea at least.

And if I understood Dr Perry correctly he already has an entity that is in the industry working with him to bring this patent to market, so time will tell where this goes; of course I will keep an ever vigilant eye on this technology and report back to you where it goes.

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