Polaraco

This is a spin off of https://www.dieseltruckresource.com/...=1#post2975443

We were getting way off topic over there. I don't feel like getting my little ones cut off by a moderator Sooo since the topic was growing, and related. . . New Thread!

Starts with this.

Polaraco

OK Bloss I'll answer your questions

"VFD" Means Variable Frequency Drive" This is an electronic device which controls AC motor speed. It adjusts the frequency to make the motor run at desired speeds and still maintain the torque. The voltage remains the same. So a motor ruinning at 480VAC @ 10 Hz is at may 15% of speed but still has the power to move the same load.

This technology is used in todays diesel locomotives, which used to run DC motors.

The The VFD's can talk to each other and adjust each others speed. Whether it's syncing speed or slowing down motors. The feature would be used for the cornering.

I haven't but a calculator to the motors yet. But if I use brake motors, it would be direct drive. Or I could use a Diff and feed it with one motor. The problem with that is I need to calc the drive shaft speed vs motor speed. I'm still working on that part. If I decide to go with the Differential design, I'll need a 3600 RPM motor. Otherwise it would be an 1800 direct drive.

patdaly

Polarco, something else to consider. We use multiple motor VFD drives on our machines, and use Permanent magnet synchronous 6 pole motors which stay in synch. I am not sure how the differential action of the wheels might affect the drive, as we never back drive them. 6 pole motors run 1200 @ 60 Hz, and we regularly run them past 100 Hz, or 2000 RPMs. You could consider also a 4 pole motor which is 1800 RPMs @ 60.

30 Kw seems like a lot for your generator, are you sure you need that big?

Polaraco

Yer right. I have a bunch of KW projects flying around in my head. Maybe it's 15 for this one. Frankly I forget. I am just about to install 9KW in wind generation on my roof. I need 3.1 KWH with the AC running

I was looking at brake motors which are less expensive. I am afraid my knowledge of motors is 2 decades old these days. I haven't really researched the motors, just figured out the HP so far. I have to find the right BHP and Torque combination. Since this is a "down the road project, I've only worked the preliminary numbers. I think the notes I have for this are next to the Geritol and Depends on the shelf

C Schomer

I've worked with older drives a quite a bit when they were very simple to program but I haven't worked on hardly anything for the last 10 yrs. I DO know they've gotten to be very complicated to program, tho. My drives need an anolog input to control the hertz and they use PID tuning constants to keep them stable. It seems like it could be done a lot simpler and skip the drive and just let the throttle control engine/hertz/motor speed. That makes more sense to me but I'm only quessing. Craig

Polaraco

Can't do that. They use a highly sufisticated system in the Locomotives now. Those are 500 HP motors or more. Today they are driven by a VFD similar to what I am talking about.

If I wanted to use DC, I could use the engine speed to control the voltage and accomplish what you are talking about. But DC brings new problems and has a lower reliability rate.

On these smaller motors, you need to keep the voltage up to keep the heat down and to deliver the torque. You have to remember the Loco's run a constant speed for hours where an auto can be all over the speed map. Even at that, I still have to keep the motors cooled with a external fan. On a loco, the diesel engine drives a large blower ehich blows direct to the motors after cooling the alternator.

Polaraco

I was a drive specialist for Eaton 20 years ago. I just got up and walked out because they kept sending me out to trouble shoot other peoples nightmares. Then get criticized because my at home job was noit getting done.

They say I was very good at it and tried to hire me back several times.

chaikwa

WOW! Y'know, for a Joisey guy, you're pretty smart!

Thank you for answering my questions and even expanding on them. To me, it makes perfect sense.

If you'd like some help with this project, (if you decide to move forward with it), I'd like to be included. I ain't smart and I ain't rich, but I DO have a knack for finding and successfully acquiring grant monies.

Thanks again!

sled4fun

I look forward to the progress of this project. I have always thought that a motor on each wheel with a genset set-up could work well. Getting rid of the differentials, transmission, transfer case and drivelines. Good luck on the project.

Polaraco

It's still in the thinking stages. . . As soon as I get some of these engines out of my garage, I'll have scrounging space

infidel

Big complaint/drawback I've been hearing of lately is the higher federal and state taxes on diesel fuel were originally implemented because semi trucks do more damage to our roads because of their heavier weights.
Not the case with a passenger vehicle or light truck.

Time to start lobbying our lawmakers in order to make this a more equitable system if more diesels are to catch on.

Lil Dog

Wow, good info here on the project. I am only familiar with VFD systems on larger industrial machinery, so I was concerned with space for the system as well as heat. I would like to see what these smaller units look like.

The AC motors now can be very reliable, and talk about having LSD! Instant torque to each wheel would be nice.

Polaraco

Oh I think getting 100+ miles per gallon will offset that. That's why the 100 HP. I want to run the engine at 900 RPM.

The other advantage to running the generator at a common speed is the fact you won't be generating as much soot. The acceleration with the VFD's is very mild as the VFD's will have to ramp the motors up. Otherwise you'd be leaving a heavy cloud of blue smoke and replacing the rear tires every time you step on the throttle.

30 HP drive tese days are smaller than a shoe box. Obviously these are going to be drive by wire like the current trucks so creating a analog signal will be easy. I just won't use a throttle pedal from a Toyota.

I also have to consider a gear box at each wheel. But given the room and the right motor dimension, I could use one motor and the original differential as well.

By increasing the HZ of the motor, we can get speed out of them. But I don't know how a motor will handle it long term at 100Hz. In my day, a inverter rated motor could take up to 80 Hz continuous. Today they have them more robust. Someone said in the other thread they spin the motors up to 100Hz but for how long? I have to dig deeper into the motors yet. But I am trying to locate used stuff for the project. Tha's why I wanted to run a Cummins 4 Banger (4BT). Wanted to transvers mount it and power the alternator with a cog belt or a flock of V belts.

One thing is for sure though. . . If I use the existing drive train, it sure would be much less expensive than going 2 gear/brake motors.

By using the belts, the other thought is to se the engine at it's most efficient RPM and adjust the speed to the Alternator with the sheeves. If that's the case, then I can use a smaller engine.

Polaraco

I need a $20 Million Grant. Your salery would be 25% of that for one year. After that, you're fired! LOL I'll take 25% too The rest I can build a fleet with.

Some oil company will buy us out in 4 years when they get wind of this.

Batteries!!! BAHHHHHH

patdaly

We run them 24/7 at up to 100 Hz for years on end, it is 5 grand an hour the machine is down, so they get really excited if one burns up. We also abuse the heck out of them with temperature, some you can literally fry eggs on, we try and get some cooling wind on them, but even that is often 150 plus degrees. The fastest I have ever documented running them is 123 Hz, which would be 2,460 RPMs for a 6 pole. I have limited those runs to 3 days or less, but here again, it is 24/7 in a very harsh environment.

We run Welco brand PM Inverter synchronous, I could get you the info if needed. In the past we ran Magnetek until they moved production overseas, then switched to A.O. Smith, and then to Reuland. All worked well, we run 2 to 5 Hp motors, up to 7 on a common VFD.

I would say stick with the PM style motor though, our 2 Hp non PM motors ran at 7.1/7.2 Amps free run, the PM units draw a fraction of that. They tried to explain it to me, but I am a Mechanical guy, no sparky.

We run exclusively Magnetek ( Yaskawa ) drives........

Now you have me thinking.........I know where there is a little 22 Hp Perkins, 15 KW ST heads are cheap on ebay, and I could probably scam a couple of 5 Hp motors here...............