Search found 121 matches

by T2
Thu, 19 Jul 2012, 13:25
Forum: Electric motors and controllers
Topic: Getting the right windings...
Replies: 77
Views: 12297

Getting the right windings...

What's up with all this high voltage stuff ? Can you tell me why EVO can't wind this motor with a lower voltage ? They know it's for a race bike do they not ? Yet they are OK for field weakening. Sorry but there is no reason they should OK that. If you go all the way to providing 636Vdc there is no ...
by T2
Fri, 13 Jul 2012, 17:44
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65656

Nevilleh's BMW

I wrote : Finally for the resistor you might want to try shunting a silicon diode across a single series field to gauge its effect. A 200 amp diode mounted on a heatsink and thereby limiting the voltage drop across the series field to 600mV might provide something close to the field weakening you ar...
by T2
Thu, 12 Jul 2012, 20:05
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65656

Nevilleh's BMW

It seems to me that your first job is to rewire your main circuit. I would retire any plans to parallel armatures until the reason for suspected cell deterioration has been diagnosed. My suggestion is to wire the two armatures directly to the controller output with no contactors in that path. In lin...
by T2
Thu, 12 Jul 2012, 07:49
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65656

Nevilleh's BMW

OTOH = On the...oh never mind As you probably can guess, I had a whole post lined up which somehow got deleted, I should have saved it in Wordpad. I am leaning towards a Lo tech solution in keeping with the maxim "Extreme Simplicity is an Essential Basis of EV Development". At present I expect your ...
by T2
Wed, 11 Jul 2012, 10:43
Forum: Members Machines
Topic: Richo's AC Handi Sports
Replies: 84
Views: 12951

Richo's AC Handi Sports

-woody, yes it is difficult for me to accept that someone would go to all that trouble with an EV and then intend to drive stick. Else why publish a graph showing the expected performance of each of four gears ? This vehicle needs but two gears. Second gear and reverse gear. Reverse gear has its ori...
by T2
Tue, 10 Jul 2012, 16:28
Forum: Members Machines
Topic: Richo's AC Handi Sports
Replies: 84
Views: 12951

Richo's AC Handi Sports

Hello again, Richo, you didn't miss the tongue-in-cheekness of my post and take umbrage did you ? Next time, play along, and express outrage but seek the high road, you'll come out looking the better for it, believe me. Close. the motor draws 8.8A in it's natural boring state - A gold star for you a...
by T2
Thu, 05 Jul 2012, 15:26
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 27078

RX400H transaxle

- johny thanks for your input you fully get this. - Richo I just put the latest piece of my rubbish on your thread in the members machines section. Somehow I think Richard Gervais has got into my writing style. - Coulomb I apologise if I have made some of my posts so overly long that you needed to s...
by T2
Thu, 05 Jul 2012, 10:21
Forum: Members Machines
Topic: Richo's AC Handi Sports
Replies: 84
Views: 12951

Richo's AC Handi Sports

Hi Richo, I see that no know-it-all has bothered to stop by and stick his nose in your business and help you design your powertrain, so since it appears that you are in such obvious need of direction I'll be that person and we'll make this a kick a$$ project. No, you don't have to thank me. But you ...
by T2
Wed, 04 Jul 2012, 08:52
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 27078

RX400H transaxle

T-J    I was not intending to rejoin this thread but your response Motor resistance is 1/4 in the lower voltage case is close. But no cigar. At least not yet anyway ! It does however give me another opportunity to get the message out there regarding rewinding for re-rating motors. The following can...
by T2
Wed, 04 Jul 2012, 06:48
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65656

Nevilleh's BMW

Hmm.. 3600 rpm is already fairly high feeding into a 4.1 : 1 rear diff. Even so I would feel that your motors can be made to perform well even approaching 4500 rpm. It's possible that maybe one motor could be encouraged to shed enough voltage to enliven the system at the top end. I am sure you may h...
by T2
Tue, 03 Jul 2012, 15:21
Forum: Members Machines
Topic: Nevilleh's BMW
Replies: 337
Views: 65656

Nevilleh's BMW

Nevilleh, I have a solution using the Logisys as series field controller or not, which you may wish to consider. I have done this with a shunt field controller for a 400Amp ASG and it worked out well. Current was limited in that application to 400amps by having only two strings of Golf cart batterie...
by T2
Fri, 29 Jun 2012, 10:44
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

-Weber what have you chosen for the base speed of your MX-5         in mph or km/hr ? Please and thank you.       Why MPH ? It's an audience thing. Americans are probably lurking here, and a mostly older demographic. I wholly agree, SI non gravitational units are much easier to apply. Plus revs/sec ...
by T2
Fri, 29 Jun 2012, 09:43
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

- Coulomb I've composed a post for your 11.28pm entry which I'm holding back since your 11.06pm post really needs to be answered in a couple of places, not to do so would be impolite. I think a lot of where we differ is in the engineering tradeoffs. Some of the things I have written I can't say I wa...
by T2
Thu, 28 Jun 2012, 17:57
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

- Johny NICE GRAPHIC damn, wish I had your computer skills - Coulomb just saw your post also. And yes I appreciate the conduction of the anti-parallel diode must give that effect. My previous post had been on the backburner for several days and I spent most of the day putting a new front end on it t...
by T2
Thu, 28 Jun 2012, 15:59
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

And now, and now, it's time for us to take our leave and abandon the world of sorcery for the moment. Now is the time to enter a universe, a place to stand and observe, while he, T2, weaves a little uninterrupted wizardry. No, we are not about to have a Harry Potter moment, this is just the calm bef...
by T2
Thu, 28 Jun 2012, 06:23
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

The metric smidge extra voltage ? Respectfully Coulomb, but are you on something ? I accept the fact that you were able to flumox me the other day re Neutral Wobble And I have to appreciate the thinking that "we got him to buy into that so let's try him with something like the er..umm... metric smi...
by T2
Wed, 27 Jun 2012, 13:22
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

-Johny Your calculations don't pass the reasonable test. A typical 3 phase VFD rectifies 3 phase to create a DC bus - typically around 1.4 times peak phase to phase - lets use 400V P-P and 560 VDC. I gather you disagree with this? This supposition will drag us way off topic ! Perhaps this should go ...
by T2
Wed, 27 Jun 2012, 11:18
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

- Weber Thank you for your input, obviously if anyone here needed straightening out just then, it was me. -Coulomb please accept my apology for the misunderstanding if I was appearing to cast doubt on math skills over in the Aus. That aside I have looked up your ref and see that Neutral Wobble is no...
by T2
Wed, 27 Jun 2012, 08:44
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

Neutral Wobble is a new term to me, here in North America. I am well aware that unlike UPS's, motor controllers don't synthesise sine waves. I have never seen any math writeup on it. So you're saying it makes as much as 15% difference. Thanks, I did not know that. Let's add this to the thread for ot...
by T2
Tue, 26 Jun 2012, 21:04
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

-Johny Doesn't the typical bridge output topology double this? Still Nope. I think you and Coulomb are doing scalar addition, you need to be doing vector addition which takes account of the 120 deg phase displacement between two legs. It's not double but root3 in fact. So your AC motor will run out ...
by T2
Tue, 26 Jun 2012, 16:12
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

I am glad you concur that the fractional V/Hz motor when spun beyond 50/60Hz frequencies becomes more efficient as far as copper loss is concerned. It is not commonly recognized. Above 6000 rpm I agree windage is no longer trivial. The usual recommendation is to remove the integral fan and mount a s...
by T2
Tue, 26 Jun 2012, 15:07
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

I am prepared to drop this but let's try one time and forget neutral wobble for now ! I am Proposing a nominal 141.4Vdc bus. a single dual mosfet leg will generate an ac rms voltage v where 2root(2) x v = 141.4 Therefore   v = 141.4/(2root(2)   =   50 Vac rms A similar leg will also generate 50Vac r...
by T2
Sun, 24 Jun 2012, 14:45
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 26765

How to convert a hybrid

-Coulomb I've been forgetting that this is a 4-pole motor, so at 50 Hz, synchronous speed is 1500 rpm, not 3000 rpm. But that doesn't explain all the difference ; considering only the V/f ratio, the base speed would be just under 4000 rpm (265/100 x 1500 rpm minus slip speed). As I pointed out since...
by T2
Fri, 15 Jun 2012, 07:55
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 27078

RX400H transaxle

Also don't forget the losses in the motor are in large part resistive losses in the copper, which are proportional to current *squared*. So motor copper losses are 16x higher in the 100V/400A case compared to the 400V/100A situation. - T-J, I know, hard to believe, but you may have made an error he...
by T2
Wed, 13 Jun 2012, 15:20
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 27078

RX400H transaxle

Infering to the possible use of an Upconverter with an induction motor I wrote "It just so happens that if you choose the right V/Hz for an induction motor you can practically achieve the same thing without one." T-J replied I'm not so sure you can. You're going to be running at a relatively high fr...