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Old July 10th, 2017, 10:29 AM   #41
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Green energy is advancing by leaps and bounds, and the cheap fossil fuel is being burned off.
By 2040, the price advantage of green energy, including nuclear,(France produces 80% of it's electricity with nuclear, they are way ahead of us on that count ) will be pronounced.
France is in the process of reducing its nuclear generation to 50%.

Green energy is going to need a lot of leaps and bounds, it is still expensive relative to the cost of fossil fuels, there isn't technology identified on the horizon that will get it there in 23 years.
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Old July 10th, 2017, 10:32 AM   #42
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I doubt if there is any AC in the car anywhere. In modern ICE vehicles the only AC is the output from the alternator but before it is used anywhere it is rectified to DC for all other uses.

All batteries put out DC and need DC, or at least rectified AC to charge. All the electronics in your house and car run on DC. Again, the AC input is rectified.

And finally, AC motors run at a constant rpm so it is difficult to vary an AC motor's speed without a huge loss in efficiency. So called diesel trains in fact use a diesel engine to drive a DC generator which powers DC motor that drive the wheels. A DC motor at constant load, will rotate at a rate proportional to the voltage sent to it, a much easier thing to control with DC.

The reason most of the world is on AC is that its voltage can be easily and efficiently stepped up and down. This allows the output of a power station to be stepped up to a high voltage for long distance transmission. And line-loss varies with amperage. So higher voltage is lower amperage is lower line-loss.

Then the voltage is stepped down before being sent to your house.
3 phase AC also offers a current density advantage for high voltage long distance transmission as well.
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Old July 10th, 2017, 03:14 PM   #43
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I doubt if there is any AC in the car anywhere. In modern ICE vehicles the only AC is the output from the alternator but before it is used anywhere it is rectified to DC for all other uses.

All batteries put out DC and need DC, or at least rectified AC to charge. All the electronics in your house and car run on DC. Again, the AC input is rectified.

And finally, AC motors run at a constant rpm so it is difficult to vary an AC motor's speed without a huge loss in efficiency. So called diesel trains in fact use a diesel engine to drive a DC generator which powers DC motor that drive the wheels. A DC motor at constant load, will rotate at a rate proportional to the voltage sent to it, a much easier thing to control with DC.

The reason most of the world is on AC is that its voltage can be easily and efficiently stepped up and down. This allows the output of a power station to be stepped up to a high voltage for long distance transmission. And line-loss varies with amperage. So higher voltage is lower amperage is lower line-loss.

Then the voltage is stepped down before being sent to your house.
Traction motors, or variable frequency drive have been around for awhile now and are replacing variable speed DC motors in all aspects. The AC drive works by converting the traction alternator output to DC (direct current) and reconverting it to a variable frequency AC which powers AC traction motors. Because AC motors operate at approximately the frequency of the current, the drives must adjust the frequency so that the motors can have a speed range of zero to maximum rpm.
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Old July 10th, 2017, 07:40 PM   #44
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I seriously doubt that it is all Direct Current and think the wheel motors are three phase Alternating Current via a DC inverter. Nicolai Tesla invented three phase AC so a Tesla car better have three phase somewhere in it.
ALL hybrids and electrics use permanent magnet (no brushes) three phase A/C for the drive motors. The electronic controllers incorporate a power inverter.
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Old July 10th, 2017, 08:07 PM   #45
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ALL hybrids and electrics use permanent magnet (no brushes) three phase A/C for the drive motors. The electronic controllers incorporate a power inverter.
Aren't power inverters still quite expensive for this type of HP?

I know they are more efficient but have prices for the inverters fallen that much?

I know that light rail transit still runs on DC.
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Old July 10th, 2017, 08:07 PM   #46
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Diesel fuel is killing millions world wide every year. The UK has recently banned diesel cars from operating in the city of London. Only lorries( semi trailers are allowed. ) The particulate matter spewed from diesel engines, has been proven to be carcinogenic. Its been proven to kill. So why is diesel still allowed to be produced in passenger cars.
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Old July 10th, 2017, 09:44 PM   #47
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ALL hybrids and electrics use permanent magnet (no brushes) three phase A/C for the drive motors. The electronic controllers incorporate a power inverter.
Thanks for this. It made me do some digging. I didn't realize the technology had gotten to this level so fast.
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Old July 10th, 2017, 10:29 PM   #48
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Traction motors, or variable frequency drive have been around for awhile now and are replacing variable speed DC motors in all aspects. The AC drive works by converting the traction alternator output to DC (direct current) and reconverting it to a variable frequency AC which powers AC traction motors. Because AC motors operate at approximately the frequency of the current, the drives must adjust the frequency so that the motors can have a speed range of zero to maximum rpm.
I have never heard three phase or single phase motors called traction motors and I worked in the field for decades before I retired. The main problem with DC motors are the commutator brushes which over time the friction makes the commutator get egg shaped and the brush material bridges the commutator gaps making dead spots. Brush material is graphite.

Three phase motors are induction motors which have no commutators or brushes and almost frictionless except for the motor bearings which don't add much friction when kept well greased.

edit: I know that the Tesla will have sealed bearings which you never grease but big induction motors have bearings that have to be greased on a regular basis. You can grease big induction motors too much which leads to motor failure. Servo motors are technically DC motors even though it uses alternating current but the alternating current never crosses zero.

Last edited by Twisted Sister; July 10th, 2017 at 10:38 PM.
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Old July 11th, 2017, 05:12 AM   #49
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Thanks for this. It made me do some digging. I didn't realize the technology had gotten to this level so fast.
Get on youtube and look up Bill Nye Science guy and find his segment on hybrid busses. While Toyota has gotten famous with the Prius and when everyone thinks hybrid that's the first thing they think of. GM (Allison transmission) has quietly revolutionized the heavy duty transportation. Many cities are running the hybrid busses with a surprisingly small diesel engine (5.7 liters) and in some cities Coke is running hybrid delivery trucks. GM using that same Allison technology was also the fist company to produce a full size hybrid SUV. Tahoe, Suburban, Yukon and Escalade. They've stopped making them now but if gas prices skyrocket again you can bet we'll see them again.

When gas was $4 a gallon I did some math. it would take 180,000 miles to pay the difference between a Corolla and a Prius (NOT including the $3000 to $12000 over sticker some people were paying) The Tahoe took just 45,000 miles to pay the difference in price. In a nation filled with ginormous SUVS and pickups, hybridizing the large vehicles would pay huge dividends.

I'm trying to change jobs, get off the road. If I land the new position I'm seriously considering a Chevy Volt as my daily driver.
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Old July 11th, 2017, 05:31 AM   #50
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The developed world is going green. The U.S. does not call the shots anymore. The Republican oligarch's are only regional players in today's world.


AND once again the U.S. is no longer LEADING the world in innovation, technology and science. We seem to fall further and further behind as our politics becomes more important than our progress.
The European countries (who seem to bear the brunt of RW jokes) are moving forward and where are we?? Still fighting in D.C. over stupid political footballs, including climate change, alternative energy and medical advances.

AND Trump's motto?? Make America Great Again?? How is that possible when our lawmakers can't even agree within their own party? Trump is reversing the progress made under Obama in areas of environment, including withdrawing from the Paris Climate deal.

The GOP has always wanted to maintain our global leadership, while longing to be BACK in Mayberry RFD...and that's where we're headed.
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