PM magnet 3 phase vs squirrel cage - advantages

[leitmotif]

Rod
I just KNEW I should have gone for that EE instead of safety.
You are talking way way above my head. How I would put all this together and make it work at this time is beyond me. However I am not afraid of the idea, gotta get some money, get a shop put together (hard to do this stuff on a boat)and other trivial details. Who knows maybe I will get that EE from the school of experience and hard knocks.

And all I wanted to do was buy the motor & controller (VFD) off the shelf bolt em together to some batteries stick the whole thing in a truck and drive off into the sunset (well rain in Seattle - it's doin that right now).

I have a couple possibles out there they are scratching their heads I guess. When they get me data sheets I will better know what my options are. Will share when I get data.

Keep thinkkin guys I can use all the brain I can find.

For you guys who keep wondering why doesnt he just bite the bullet and go DC well I want to see if I can do it with AC - everyone else (almost) is so why not I? DC is the fallback position of course already have list of proven components and vendors.


Dan Bentler

 

[Leadfoot]

Most VFDs today use a rectifier front end. Connecting a battery pack directly the DC bus has been done before. I have worked on a UPS using a Yaskawa inverter fed with batteries.

You most certainly can use a 200 volt inverter with the 250 volt DC battery set up and power a 230 volt off the shelf motor. What horse power drive and inverter do you feel is necessary?

Remember, as the tranny shifts to a higher gear, the engine speed drops. The motor you want to use must also drop in rpm when you go to a higher gear. Using an off the shelf inverter you could program more than one accel or decel time using the digital inputs.

I wonder how efficient is that voltage doubler? Everytime you step up or down a voltage you must consider the watt losses AKA I squared R losses. Yes, a 460 volt 60 hp motor has less IR loss than a 230 volt 60 hp motor. We are also not talking long transmission lines.

 

[rsdoran]

Just another quick thought, you do realize a 60HP motor and equivalent drive will cost around $10,000 (or more whether AC or DC)...this is not counting batteries etc needed.

 

[leitmotif]

Most VFDs today use a rectifier front end. Connecting a battery pack directly the DC bus has been done before. I have worked on a UPS using a Yaskawa inverter fed with batteries.
REPLY What size inverter (output Kw)

You most certainly can use a 200 volt inverter with the 250 volt DC battery set up and power a 230 volt off the shelf motor. What horse power drive and inverter do you feel is necessary?
REPLY Well if two possibilities don't worrk out, then the is the AC drive fallback position. But this is what I had in mind. The motor size is an estimated 20 to 30 probably will settle on about 25.


Remember, as the tranny shifts to a higher gear, the engine speed drops. The motor you want to use must also drop in rpm when you go to a higher gear. Using an off the shelf inverter you could program more than one accel or decel time using the digital inputs.
REPLY Hopefully the download to attach an excel file worked. In there I calculated the drive train overall reduction and motor speeds at various MPH and various gears. Kindly do not take my torque calcs too seriously - I think I screwed em up.

I wonder how efficient is that voltage doubler? Everytime you step up or down a voltage you must consider the watt losses AKA I squared R losses. Yes, a 460 volt 60 hp motor has less IR loss than a 230 volt 60 hp motor. We are also not talking long transmission lines.

REPLY Well if I can go with a 230 inverter on a 250VDC battery I don't need a doubler and eliminate one more thing to break.


RON DORAN
Thanks for reality dose. I checked with Mitsubishi - one of their motors and drives was about 5 K.

If I go DC the motor is about 1300, I think the controller is about 1000, supposedly total out to 5 k including battery.
Cost is an issue, I do NOT expect it to be cheaper than DC, and I guess I better assume an allowable increase. Think I will assume right now I will accept another 30% for AC.

 

[danpantea]

I would look at a windmill generator PM (permanent magnet motor) if you want to go this route. PM's can break very often compared to regular windings. Remember the losses in efficiency are proportional to the deviation from the designed operating frequency for AC motors (a motor designed for 60 Hz that is runned at 800 Hz will have extreme loses). A DC motor is the only cheap alternative unless you want to carry a trunk full of spare parts. The program for the drive is probably going to take years to get something safe that will not kill the transmission. Why don't you buy a golf cart? It is probably going to be cheaper and safer.

 

[rdrast]

Oh, I'm going to pull it apart one of these days, just because I have just not had time in the past year.

I've had it since June 2004 (after a 6 month wait), and aside from an unfortunate incident with a deer, it's been a fantastic vehicle. The electric motor(s) provide for a very quick acceleration from zero, as well as quick power for passing. The gas engine runs all the time at speeds over about 30 mph, but is controlled by the computer, not the pedel, to deliver whatever power is needed to the 'transmission'.

There is no actual transmission, the main drive system is made up of the Engine, the AC Motor (essentially directly coupled to the drive shaft), and the DC Motor/Generator/Starter all coupled to a planetary differential. The main generator is used to shed speed from (or add to) the differential, to keep the gas engine running in it's optimum power band.

All in all, it's pretty neat, and will cruise at over 90 without any problems.

It is ugly after hitting a deer though, but that was fixable.

Uh oh I hope I have not stimulated your curiosity.

If it ain't broke don't tinker with it.
DO NOT take that apart on my account.

How long have you had the car?
What do you think of this electric drive stuff?
Thanks for info.

Dan Bentler