Search found 51 matches

by EVLearner
Tue, 24 Feb 2009, 20:14
Forum: Electric motors and controllers
Topic: Cheap 3 Phase Controller
Replies: 3
Views: 2358

Cheap 3 Phase Controller

A few weeks ago while web searching about microprocessor 3 phase controllers, one article was talking about a washing machine, and then it struck me that our home washing machine has autoprogrammable speeds, and has a 3 phase motor. "> http://www.freescale.com/files/microcontrollers/doc/app_note/AN3...
by EVLearner
Mon, 16 Feb 2009, 17:16
Forum: Electric motors and controllers
Topic: AC motors, multipoles, torque
Replies: 549
Views: 69752

AC motors, multipoles, torque

In another look at the torque versus revs situation - and the current drawn by an AC motor, I was considering that the frequency is independent and that in the low frequency range (say 20 Hz to say 60 Hz) the motor would be Star (Wye) connected and from say 50 Hz to say 150 Hz the motor would be Del...
by EVLearner
Mon, 16 Feb 2009, 17:04
Forum: Electric motors and controllers
Topic: AC motors, multipoles, torque
Replies: 549
Views: 69752

AC motors, multipoles, torque

Hi Woody

Something tells me that three of the magnetic fields are reversed in the parallel Star Dahlander arrangement and this could cause the rotor to abruptly spin in reverse if these were switched while in motion - that could be interesting!!
by EVLearner
Mon, 16 Feb 2009, 14:29
Forum: Electric motors and controllers
Topic: AC or DC?
Replies: 99
Views: 13793

AC or DC?

Good questions Woody I was actually considering that the frequency is independent and that in the low frequency range (say 20 Hz to say 60 Hz) the motor would be Star (Wye) connected and from say 50 Hz to say 150 Hz the motor would be Delta connected! Now as far as current goes, much of the current ...
by EVLearner
Mon, 16 Feb 2009, 06:50
Forum: AEVA NSW Branch
Topic: Sydney Lurkers
Replies: 46
Views: 7764

Sydney Lurkers

Hi Masky I too live in Turramura and an a retired Electronics Engineer, and my hands are not dirty enough! For the past 3 months I have been wondering how to 'attack this issue' and the answers are now coming like the rain - a 10 to 18 kW AC motor with a good AC controller and the batteries will be ...
by EVLearner
Mon, 16 Feb 2009, 04:00
Forum: Electric motors and controllers
Topic: AC motors, multipoles, torque
Replies: 549
Views: 69752

AC motors, multipoles, torque

Thanks antiscab, you have really cleared up an area that I have had trouble sleeping over in the last month or so - now I can sleep like a baby!! BTW, in hindsight with the Torque curves provided by Woody (I think) it seems not that hard to switch from Wye to Delta while the motor is running (increa...
by EVLearner
Mon, 16 Feb 2009, 00:35
Forum: Electric motors and controllers
Topic: Tritium Wavesculptor
Replies: 22
Views: 5154

Tritium Wavesculptor

Hi bga Sounds like you are on the same wavelength as I am on (and that is good)! Your reasoning for the IGBTs is exactly what I had considered - and I can see the voltage going up - not down (I started thinking in terms of 144 V then moved to 200 V DC. Now, depending on the batteries, 5 groups of 4 ...
by EVLearner
Sun, 15 Feb 2009, 06:09
Forum: Electric motors and controllers
Topic: AC motors, multipoles, torque
Replies: 549
Views: 69752

AC motors, multipoles, torque

Hi Antiscab Understood, so about 10 - 12 kW (at 50 Hz) is about right for a small / medium car? yes? Or should I opt for about say 15 kW? 3x base speed is about 150 Hz, right, so could I increase the frequency to say 400 Hz and spin the rotor at say 8x the nominal rotor speed, so a nominal 1440 rpm ...
by EVLearner
Sun, 15 Feb 2009, 05:57
Forum: Electric motors and controllers
Topic: Wheel Motors
Replies: 24
Views: 6505

Wheel Motors

Hi Benonymous While at the Green (Gasoline) Car Innovation Fund (Fraud) meeting in Sydney a few weeks ago, I spoke with a lady from Gosford who said she was developing a magnetically efficient wheel/hub motor. She avoided the technical details as they were obviously confidential, but I had the disti...
by EVLearner
Sun, 15 Feb 2009, 04:00
Forum: Electric motors and controllers
Topic: AC motors, multipoles, torque
Replies: 549
Views: 69752

AC motors, multipoles, torque

Would I be right in assuming that an AC motor rated at about 15 to 20 kW is about the right size for the average small/medium car?

Similarly an AC motor rated at about 20 - 25 kW is about right for the standard Falcon / Holden / Magna?
by EVLearner
Sun, 15 Feb 2009, 02:41
Forum: Electric motors and controllers
Topic: How Does Regeneration Work
Replies: 46
Views: 6720

How Does Regeneration Work

Yes - but I don't guess! There is a very big void here that needs methodical analysis so that the regeneration and braking can work in concert with maximum efficiency. As our illustrious PM keeps saying again, and again, and again.... "It's going to take some time" (And that was 3 phases of it!)
by EVLearner
Sun, 15 Feb 2009, 00:18
Forum: Electric motors and controllers
Topic: How Does Regeneration Work
Replies: 46
Views: 6720

How Does Regeneration Work

Yeah, but when I think about it: if the battery is to be charged by the stator then the stator voltage will be larger than the battery voltage, and so the current flow will be in reverse to it being used as a motor. This being the case, the voltage across the IGBT will be reversed as the current flo...
by EVLearner
Sat, 14 Feb 2009, 18:08
Forum: Technical and conversion discussion
Topic: Accelerator Pedal Sensors
Replies: 41
Views: 5453

Accelerator Pedal Sensors

I must admit the first thing that came to my mind was a noisy (carbon)pot, and the second thing wasa conductive plastic pot, which I used in several projects, but.... they are more expensive. The photo conductive resistor sounds good and the moving parts are minimised, as does the Hall effect resist...
by EVLearner
Sat, 14 Feb 2009, 15:59
Forum: Electric motors and controllers
Topic: How Does Regeneration Work
Replies: 46
Views: 6720

How Does Regeneration Work

So, mentally, I am making a 3 phase controller, using IGBTs from a nominal 200 V battery, runnning a 15 kW squirrel cage motor! I can see how to accelerate (above the critical slip frequency) by increasing the drive frequency (and probably using an FPLA/EPROM/uPROC to get the 3 phases). By putting t...
by EVLearner
Sat, 14 Feb 2009, 00:23
Forum: Electric motors and controllers
Topic: AC or DC?
Replies: 99
Views: 13793

AC or DC?

Hi Tonic That is a great summation of the basic electrical measures, just the Volt needs a bit of clarification. What you had was: "A Volt (V) is a measure of the amount of Energy that one Coulomb contains; the higher the Volts, the greater the Energy." and this is a bit misleading. The volt is the ...
by EVLearner
Wed, 11 Feb 2009, 17:28
Forum: Electric motors and controllers
Topic: How Does Regeneration Work
Replies: 46
Views: 6720

How Does Regeneration Work

Thanks, I think that I get it "Of course, you will eventually get to almost zero RPM for the induction motor, or almost zero "output" voltage for the DC motor." It seems to me that there is a virtually linear correlation (in the AC case) between drive frequency and shaft revs (frequency) - providing...
by EVLearner
Wed, 11 Feb 2009, 04:15
Forum: Electric motors and controllers
Topic: Introductions & initial thoughts...
Replies: 16
Views: 2725

Introductions & initial thoughts...

Hi Marcus Welcome to the crazies! Richo has the basics of the engineering in a nutshell and from that point, it is a logistics exercise, and no! I have not cracked the magic formulae yet. I somehow think that there is a lot more than meets the eye, and you were talking about having a direct drive - ...
by EVLearner
Wed, 11 Feb 2009, 04:02
Forum: Electric motors and controllers
Topic: AC or DC?
Replies: 99
Views: 13793

AC or DC?

Just a slight correction here: "A is amps, a couloumb of charge (a whole bunch of electrons) per second flowing through something. " Not quite. It works as per this: Electricity is basically a whole lot of (negatively charged) electrons; those little planetry things that spin around atoms' neuclii! ...
by EVLearner
Tue, 10 Feb 2009, 06:19
Forum: Electric motors and controllers
Topic: How Does Regeneration Work
Replies: 46
Views: 6720

How Does Regeneration Work

I'm almost there! Are you saying that by reducing the cyclic rate of the variable frequency drive to say 48.41 Hz, that the rotor in spinnning at say 1470 rpm, will try to slow down to 1455 rpm and produce a back emf (with current) that feeds backwards through the bypassing diodes to pull the rotor'...
by EVLearner
Tue, 10 Feb 2009, 02:02
Forum: Electric motors and controllers
Topic: How Does Regeneration Work
Replies: 46
Views: 6720

How Does Regeneration Work

As everything is starting to come together mentally, I am confused at how AC regeneration will work. Assuming that I have a variable frequency drive, and the vehicle is moving and I want to slow down, is it simply a matter of slowing down the drive frequency so that the motor moves into generator mo...
by EVLearner
Mon, 09 Feb 2009, 22:50
Forum: Electric motors and controllers
Topic: AC or DC?
Replies: 99
Views: 13793

AC or DC?

Hi bga If you consider IGBTs instead of FETs, the IGBTs can switch over 300 A, and can take up to about 1600 V and these usually come in series connected pairs, making them ideal for AC motor control. I don't know how much the FETs cost (by the dozen), but as far as I can tell the IFBTs cost about $...
by EVLearner
Mon, 09 Feb 2009, 15:41
Forum: Electric motors and controllers
Topic: AC or DC?
Replies: 99
Views: 13793

AC or DC?

That's right, and the next consideratrion is whether to align with 240 VAC Delta wound (which is 415 V Star wound) - as these motors are common worldwide, or to consider 115 V Delta Wound (which is 230 V star wound) and these motors are currently rather uncommon anywhere. The problem eminates from p...
by EVLearner
Mon, 09 Feb 2009, 07:38
Forum: Electric motors and controllers
Topic: Tritium Wavesculptor
Replies: 22
Views: 5154

Tritium Wavesculptor

Hi bga Nothing is wrong with software - providing it is used in an eligant manner, and when it comes to a 3 phase (120 deg apart) firing system, with a variable frequency drive, I see strong uses for both digital to work the angles and analogue to manage the PWM - but I am bending towards doing the ...
by EVLearner
Sun, 08 Feb 2009, 21:14
Forum: Electric motors and controllers
Topic: AC or DC?
Replies: 99
Views: 13793

AC or DC?

No you are not ignorant, as I am rather confused too and that it why I purchased a little 1.5 kW 3 phase motor last week to get a better underatanding of what is going on here! It's cheap and the connectors will cost more than the motor - but at least I will be able to connect a small controller and...
by EVLearner
Sun, 08 Feb 2009, 19:00
Forum: Electric motors and controllers
Topic: AC or DC?
Replies: 99
Views: 13793

AC or DC?

"You could of course just use a 26kW 50Hz motor and a lower voltage, higher current inverter, but then the motor weighs a lot more,..." I don't understand. Surely the motor magnetic circuit would be the same but the winding turns would be less with thicker wire - (or parallelled thinner wire to fill...