Hi all, first post
Can anyone tell me the maximum "installed" torque I should reasonably expect from a WarP 9 motor? I need to know the maximum torque I should consider when designing my taper lock motor/flywheel joint. The only motor curve I have only shows torque values under about 80 ft-#'s. I understand torque is a function of amps and that could be limited by either my controller (Zilla Z1K LV) or my batteries (yet to be determined). I was told by one source the maximum torque the motor could produce could be as high as 450 ft-#'s. This doesn't seem reasonable to me. Any thoughts? thanks, -- MikeB2 _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
Hi Mike,
Torque is reasonably proportional to amps, so you can get an approximate figure at 1000A by extrapolating NetGain's graphs (https://www.zeva.com.au/store/images/large/32-WarP_9_Graph.jpg ) Subtracting ~50A for static drag and working with a torque coefficient of ~0.25 foot-pounds per amp for the Warp 9, it looks like you can expect something like 250 foot-pounds at 1000A? (The 450ft-lbs suggested might be with a Z2K?) -Ian On 20/07/2008, at 10:37 PM, Mike Boyles wrote: > Hi all, first post > > Can anyone tell me the maximum "installed" torque I should reasonably > expect from a WarP 9 motor? I need to know the maximum torque I should > consider when designing my taper lock motor/flywheel joint. The only > motor curve I have only shows torque values under about 80 ft-#'s. I > understand torque is a function of amps and that could be limited by > either my controller (Zilla Z1K LV) or my batteries (yet to be > determined). I was told by one source the maximum torque the motor > could produce could be as high as 450 ft-#'s. This doesn't seem > reasonable to me. Any thoughts? > thanks, > > -- > MikeB2 > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ > ev > > _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
Thanks Ian,
That number looks a lot more reasonable since the tires will slip at about 90 ft-#'s in first gear. My taper loc is good to transmit about 750 ft-#'s so I think it will be ok. On 7/20/08, Ian Hooper <[hidden email]> wrote: > Hi Mike, > > Torque is reasonably proportional to amps, so you can get an > approximate figure at 1000A by extrapolating NetGain's graphs (https://www.zeva.com.au/store/images/large/32-WarP_9_Graph.jpg > ) > > Subtracting ~50A for static drag and working with a torque coefficient > of ~0.25 foot-pounds per amp for the Warp 9, it looks like you can > expect something like 250 foot-pounds at 1000A? > > (The 450ft-lbs suggested might be with a Z2K?) > > -Ian > > On 20/07/2008, at 10:37 PM, Mike Boyles wrote: > > > Hi all, first post > > > > Can anyone tell me the maximum "installed" torque I should reasonably > > expect from a WarP 9 motor? I need to know the maximum torque I should > > consider when designing my taper lock motor/flywheel joint. The only > > motor curve I have only shows torque values under about 80 ft-#'s. I > > understand torque is a function of amps and that could be limited by > > either my controller (Zilla Z1K LV) or my batteries (yet to be > > determined). I was told by one source the maximum torque the motor > > could produce could be as high as 450 ft-#'s. This doesn't seem > > reasonable to me. Any thoughts? > > thanks, > > > > -- > > MikeB2 > > > > > > _______________________________________________ > > For general EVDL support, see http://evdl.org/help/ > > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ > > ev > > > > > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev > > -- MikeB2 _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Mike Boyles
Hello Mike,
I have now been running my EV now for 6 years that weighs 7000 lbs with a Warp 9 , Zilla 1K and 180 V T-145 Trojan battery pack. It uses a Electro Auto taper lock coupling and adapter plate that is connected to a manual Saganaw 3-speed transmission that has a 1st gear ratio of 3.5:1 and with a 5.57:1 differential gear, makes a overall ratio of 19.495:1 and in 2nd gear it has a overall ratio of 13.925:1. Otmar of Café Electric was scared that the Zilla 1K would not do the job and I would need a Zilla 2k. I said not to worry, I have the gears and I have been running with a 900 amp controller for 27 years with no problem and the maximum motor ampere I ever pull was 600 amps while going up a 7% hill every day for the last 10 years. Tires are high pressure type set at 65 PSI, which has a rolling circumference of 94 inches. On very smooth dead level grade at 25 mphs at a gear ratio of 19.495:1, then motor ampere is 100 amps while the battery amps is 20 amps. When the grade gets rough and bumper, the motor amps goes to 150 amps and the battery amps to 50 amps. If I shift to 2nd gear or 13.925:1 my motor amps go to 200 amps with a battery amps of 75 amps at 30 to 35 mph where I normally drive. You must be able to deride all this data and more to determine what the torque will be at startup, at a given motor rpm and speed. To find this data on the Warp motors it is best to contact: George F. Hamstra at NetGain [hidden email] Tell him all what vehicle you want a motor to be install in. You need to know the weight, weight with battery packs, what types of batteries, the transmission gear ratio, differential gear ratio, size of tires, the diameter of tires, type of tires, what type of controller you are using, frontal area of the vehicle, and the average speed and top speed you want to go and for how long. George will make up a complete spread sheet for your vehicle and will E-mail you the data. If you want to see the formulas for calculating a EV performance see: http://www.geocities.com/capecanaveral/lab/8679/equations.html You must first solve the first formula so the results are then inputted into the next and so on. Roland ----- Original Message ----- From: "Mike Boyles" <[hidden email]> To: <[hidden email]> Sent: Sunday, July 20, 2008 8:37 AM Subject: [EVDL] motor torque question > Hi all, first post > > Can anyone tell me the maximum "installed" torque I should reasonably > expect from a WarP 9 motor? I need to know the maximum torque I should > consider when designing my taper lock motor/flywheel joint. The only > motor curve I have only shows torque values under about 80 ft-#'s. I > understand torque is a function of amps and that could be limited by > either my controller (Zilla Z1K LV) or my batteries (yet to be > determined). I was told by one source the maximum torque the motor > could produce could be as high as 450 ft-#'s. This doesn't seem > reasonable to me. Any thoughts? > thanks, > > -- > MikeB2 > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev > > _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
Thanks Roland,
George is the one who told me the "maximum" torque from the motor "could" be as high as 450 ft-#'s. Though he did not have the benefit of all the other data. I have run through the calculations based on what I know today and did not see anything like a requirement for a torque that high. Thanks for sharing your experience, that makes me feel even better about what I am doing. I am a mechanical guy (responsible for off highway vehicle design) more comfortable with hydro-dynamic transmissions and diesel engines. I have a lot to learn about things electrical. On 7/20/08, Roland Wiench <[hidden email]> wrote: > Hello Mike, > > I have now been running my EV now for 6 years that weighs 7000 lbs with a > Warp 9 , Zilla 1K and 180 V T-145 Trojan battery pack. It uses a Electro > Auto taper lock coupling and adapter plate that is connected to a manual > Saganaw 3-speed transmission that has a 1st gear ratio of 3.5:1 and with a > 5.57:1 differential gear, makes a overall ratio of 19.495:1 and in 2nd gear > it has a overall ratio of 13.925:1. > > Otmar of Café Electric was scared that the Zilla 1K would not do the job and > I would need a Zilla 2k. I said not to worry, I have the gears and I have > been running with a 900 amp controller for 27 years with no problem and the > maximum motor ampere I ever pull was 600 amps while going up a 7% hill every > day for the last 10 years. > > Tires are high pressure type set at 65 PSI, which has a rolling > circumference of 94 inches. > > On very smooth dead level grade at 25 mphs at a gear ratio of 19.495:1, then > motor ampere is 100 amps while the battery amps is 20 amps. When the grade > gets rough and bumper, the motor amps goes to 150 amps and the battery amps > to 50 amps. > > If I shift to 2nd gear or 13.925:1 my motor amps go to 200 amps with a > battery amps of 75 amps at 30 to 35 mph where I normally drive. > > You must be able to deride all this data and more to determine what the > torque will be at startup, at a given motor rpm and speed. > > To find this data on the Warp motors it is best to contact: > > George F. Hamstra at NetGain [hidden email] > > Tell him all what vehicle you want a motor to be install in. You need to > know the weight, weight with battery packs, what types of batteries, the > transmission gear ratio, differential gear ratio, size of tires, the > diameter of tires, type of tires, what type of controller you are using, > frontal area of the vehicle, and the average speed and top speed you want to > go and for how long. > > George will make up a complete spread sheet for your vehicle and will E-mail > you the data. > > If you want to see the formulas for calculating a EV performance see: > http://www.geocities.com/capecanaveral/lab/8679/equations.html > > You must first solve the first formula so the results are then inputted into > the next and so on. > > Roland > > > ----- Original Message ----- > From: "Mike Boyles" <[hidden email]> > To: <[hidden email]> > Sent: Sunday, July 20, 2008 8:37 AM > Subject: [EVDL] motor torque question > > > > Hi all, first post > > > > Can anyone tell me the maximum "installed" torque I should reasonably > > expect from a WarP 9 motor? I need to know the maximum torque I should > > consider when designing my taper lock motor/flywheel joint. The only > > motor curve I have only shows torque values under about 80 ft-#'s. I > > understand torque is a function of amps and that could be limited by > > either my controller (Zilla Z1K LV) or my batteries (yet to be > > determined). I was told by one source the maximum torque the motor > > could produce could be as high as 450 ft-#'s. This doesn't seem > > reasonable to me. Any thoughts? > > thanks, > > > > -- > > MikeB2 > > > > > > _______________________________________________ > > For general EVDL support, see http://evdl.org/help/ > > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev > > > > > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev > > -- MikeB2 _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Mike Boyles
Sounds about right. Lifebatt is doing a project in the UK using a
WarP 9 with a LogiSystems 750A controller. They quote 500 ft-lbs of torque. See http://www.lifebatt.co.uk/r2/index.html Maximum torque for a DC motor is at 0 RPM. The reality if the tires will probably break friction before you get to 500 ft lbs, so they will be your limiting factor. On Jul 20, 2008, at 10:37 AM, Mike Boyles wrote: > Hi all, first post > > Can anyone tell me the maximum "installed" torque I should reasonably > expect from a WarP 9 motor? I need to know the maximum torque I should > consider when designing my taper lock motor/flywheel joint. The only > motor curve I have only shows torque values under about 80 ft-#'s. I > understand torque is a function of amps and that could be limited by > either my controller (Zilla Z1K LV) or my batteries (yet to be > determined). I was told by one source the maximum torque the motor > could produce could be as high as 450 ft-#'s. This doesn't seem > reasonable to me. Any thoughts? > thanks, > > -- > MikeB2 > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ > ev _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
> Sounds about right. Lifebatt is doing a project in the UK using a
> WarP 9 with a LogiSystems 750A controller. They quote 500 ft-lbs of > torque. See > > http://www.lifebatt.co.uk/r2/index.html > > Maximum torque for a DC motor is at 0 RPM. The reality if the tires > will probably break friction before you get to 500 ft lbs, so they > will be your limiting factor. I'm pretty sure the 500ft-lbs they are talking about is /wheel/ torque not motor torque. _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Ian Hooper-3
Ian,
That's odd, I always thought the torque equation for series wound motors was T=c*I^2, So 70ft-lb at 334.5A is 625ft-lb (less probably due to less than optimal timing) at 1000A. That's troubling because if im wrong then I need to redo a lot of the calculations for my conversion. Matt -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Ian Hooper Sent: Sunday, 20 July 2008 10:58 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] motor torque question Hi Mike, Torque is reasonably proportional to amps, so you can get an approximate figure at 1000A by extrapolating NetGain's graphs (https://www.zeva.com.au/store/images/large/32-WarP_9_Graph.jpg ) Subtracting ~50A for static drag and working with a torque coefficient of ~0.25 foot-pounds per amp for the Warp 9, it looks like you can expect something like 250 foot-pounds at 1000A? (The 450ft-lbs suggested might be with a Z2K?) -Ian On 20/07/2008, at 10:37 PM, Mike Boyles wrote: > Hi all, first post > > Can anyone tell me the maximum "installed" torque I should reasonably > expect from a WarP 9 motor? I need to know the maximum torque I should > consider when designing my taper lock motor/flywheel joint. The only > motor curve I have only shows torque values under about 80 ft-#'s. I > understand torque is a function of amps and that could be limited by > either my controller (Zilla Z1K LV) or my batteries (yet to be > determined). I was told by one source the maximum torque the motor > could produce could be as high as 450 ft-#'s. This doesn't seem > reasonable to me. Any thoughts? > thanks, > > -- > MikeB2 > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ For subscription > options, see http://lists.sjsu.edu/mailman/listinfo/ > ev > > _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev -- No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.5.2/1562 - Release Date: 19/07/2008 2:01 PM _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
Matt,
I'm no expert, but my understanding is that coils have a point where they saturate. At low currents (below saturation) you would expect to see a square relation, transitioning to a linear one as one of the coils saturates. Steve On 21/07/08 5:01 PM, "matt" <[hidden email]> wrote: > Ian, > > That's odd, I always thought the torque equation for series wound motors was > T=c*I^2, > So 70ft-lb at 334.5A is 625ft-lb (less probably due to less than optimal > timing) at 1000A. > > That's troubling because if im wrong then I need to redo a lot of the > calculations for my conversion. > > Matt > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf > Of Ian Hooper > Sent: Sunday, 20 July 2008 10:58 PM > To: Electric Vehicle Discussion List > Subject: Re: [EVDL] motor torque question > > Hi Mike, > > Torque is reasonably proportional to amps, so you can get an approximate > figure at 1000A by extrapolating NetGain's graphs > (https://www.zeva.com.au/store/images/large/32-WarP_9_Graph.jpg > ) > > Subtracting ~50A for static drag and working with a torque coefficient of > ~0.25 foot-pounds per amp for the Warp 9, it looks like you can expect > something like 250 foot-pounds at 1000A? > > (The 450ft-lbs suggested might be with a Z2K?) > > -Ian _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Matt Lacey
matt wrote:
> That's odd, I always thought the torque equation for series wound > motors was T=c*I^2. So 70ft-lb at 334.5A is 625ft-lb (less probably > due to less than optimal timing) at 1000A. The T=c1*I^2 equation works for low currents (below nameplate current). But as you go higher, it gradually changes to simply T=c2*I as the iron moves into saturation. (c1 and c2 are different constants). -- Ring the bells that still can ring Forget the perfect offering There is a crack in everything That's how the light gets in -- Leonard Cohen -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
I have a couple of Kill A Watt meters,
http://www.p3international.com/products/special/P4400/P4400-CE.html These work great for such a low cost device. A few have mentioned a similar 240Vac version, but I could not find which one they were talking about. Was it this http://www.pat-training.co.uk/230V_electricity_meter.htm Are there any other brands that people have used? Thanks, Rod _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Lee Hart
Ah ok, that makes sense.
Any ideas as to what current a warp 9 would go into saturation? Does anyone know at what current density iron goes into saturation? Matt -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Lee Hart Sent: Monday, 21 July 2008 10:26 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] motor torque question matt wrote: > That's odd, I always thought the torque equation for series wound > motors was T=c*I^2. So 70ft-lb at 334.5A is 625ft-lb (less probably > due to less than optimal timing) at 1000A. The T=c1*I^2 equation works for low currents (below nameplate current). But as you go higher, it gradually changes to simply T=c2*I as the iron moves into saturation. (c1 and c2 are different constants). -- Ring the bells that still can ring Forget the perfect offering There is a crack in everything That's how the light gets in -- Leonard Cohen -- Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev -- No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.5.2/1562 - Release Date: 19/07/2008 2:01 PM _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by rodhower
hi Rod,
What are you using it to measure? Here in Australia were stuck with a ms-6115 from electus distribution, which doesn't have any harmonic distortion correction (though its power factor correction is fairly accurate). Basically it was useless for measuring power draw from a switch mode power supply (or just about any good battery charger). If you are intending to use a low cost power meter for measuring your Evs energy requirement from the grid, make sure you compare it to a known accurate meter first. Matt -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Rod Hower Sent: Monday, 21 July 2008 10:33 PM To: Electric Vehicle Discussion List Subject: [EVDL] Kill A Watt for 240Vac I have a couple of Kill A Watt meters, http://www.p3international.com/products/special/P4400/P4400-CE.html These work great for such a low cost device. A few have mentioned a similar 240Vac version, but I could not find which one they were talking about. Was it this http://www.pat-training.co.uk/230V_electricity_meter.htm Are there any other brands that people have used? Thanks, Rod _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev -- No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.5.2/1562 - Release Date: 19/07/2008 2:01 PM _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Matt Lacey
--- On Mon, 7/21/08, matt <[hidden email]> wrote: > Any ideas as to what current a warp 9 would go into > saturation? > Does anyone know at what current density iron goes into > saturation? > > Matt > Hi Matt, It is not current density, but flux density. So it all depends on the particular magnetic circuit design and turns per coil on the field for the particular motor in question. For sheet steel used for motor laminations, saturation starts about 1.0 tesla(T) and knees over to heavy saturation at about 1.3 T. Without having the design specs for the motor, or running a no-load magnetization curve, I can't give you an exact figure for current. However, it was Lee I think, gave some good advice. Above the motor's one hour rated current, chances are you're getting into saturation. Another 100 amps and you're well into it. So at current limits, like 400 amps or above on a series motor of that size, no doubt you're saturated and torque per amp in nearly linear. Regards, Jeff M _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
Thanks for the help guys, much appreciated.
Sounds like I have yet more researching to do. Cheers, Matt -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Jeff Major Sent: Monday, 21 July 2008 11:46 PM To: Electric Vehicle Discussion List Subject: Re: [EVDL] motor torque question --- On Mon, 7/21/08, matt <[hidden email]> wrote: > Any ideas as to what current a warp 9 would go into saturation? > Does anyone know at what current density iron goes into saturation? > > Matt > Hi Matt, It is not current density, but flux density. So it all depends on the particular magnetic circuit design and turns per coil on the field for the particular motor in question. For sheet steel used for motor laminations, saturation starts about 1.0 tesla(T) and knees over to heavy saturation at about 1.3 T. Without having the design specs for the motor, or running a no-load magnetization curve, I can't give you an exact figure for current. However, it was Lee I think, gave some good advice. Above the motor's one hour rated current, chances are you're getting into saturation. Another 100 amps and you're well into it. So at current limits, like 400 amps or above on a series motor of that size, no doubt you're saturated and torque per amp in nearly linear. Regards, Jeff M _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev -- No virus found in this incoming message. Checked by AVG. Version: 7.5.524 / Virus Database: 270.5.2/1562 - Release Date: 19/07/2008 2:01 PM _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Matt Lacey
This is interesting. The toque is proportional to the strength of the
magnetic field... correct? So, are we saying that the strength of the magnetic field starts out as a squared function of current, and then transitions to a linear function of current... and this is because of what? Eddy currents in the iron? Saturation? I'm just trying to understand this? There was another thread on how to improve the old tried and true series wound DC motor. Sounds like different material to avoid saturation would be a good idea. On Jul 21, 2008, at 10:52 AM, matt wrote: > Ah ok, that makes sense. > Any ideas as to what current a warp 9 would go into saturation? > Does anyone know at what current density iron goes into saturation? > > Matt > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] > On Behalf > Of Lee Hart > Sent: Monday, 21 July 2008 10:26 PM > To: Electric Vehicle Discussion List > Subject: Re: [EVDL] motor torque question > > matt wrote: >> That's odd, I always thought the torque equation for series wound >> motors was T=c*I^2. So 70ft-lb at 334.5A is 625ft-lb (less probably >> due to less than optimal timing) at 1000A. > > The T=c1*I^2 equation works for low currents (below nameplate > current). > But as you go higher, it gradually changes to simply T=c2*I as the > iron > moves into saturation. (c1 and c2 are different constants). > > -- > Ring the bells that still can ring > Forget the perfect offering > There is a crack in everything > That's how the light gets in -- Leonard Cohen > -- > Lee A. Hart, 814 8th Ave N, Sartell MN 56377, > leeahart_at_earthlink.net > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ > ev > > > -- > No virus found in this incoming message. > Checked by AVG. > Version: 7.5.524 / Virus Database: 270.5.2/1562 - Release Date: > 19/07/2008 > 2:01 PM > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ > ev _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Mike Boyles
My first post was firing from the hip, now for some back-of-the-envelope. Working backwards from the Amps, Volts, voltage sag, an assumption that the motor drops out of current limit at mid rpm, etc. At mid rpm, I estimate the motor makes about 180 ft*lbs of torque with no current multiplication (nice to see that is close to your estimate). So Peter you are right, it does look like that are quoting wheel torque (unless they have a whole lotta current multiplication going on).
----- Original Message ---- From: Peter VanDerWal <[hidden email]> ... _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Roger Heuckeroth
Hi Roger,
A few comments inserted...... --- On Mon, 7/21/08, Roger Heuckeroth <[hidden email]> wrote: > This is interesting. The toque is proportional to the > strength of the > magnetic field... correct? The torque is the product of armature current and flux. > So, are we saying that the > strength of the > magnetic field starts out as a squared function of current, > and then > transitions to a linear function of current... and this is > because of > what? Eddy currents in the iron? Saturation? Saturation. Flux no longer increases but armature current can. > I'm just trying to understand this? There was another > thread on how > to improve the old tried and true series wound DC motor. > Sounds like > different material to avoid saturation would be a good > idea. There are only a few ferromagnetic materials, like iron. All other materials have basically the permeability of a vacuum. So use wood or plastic to avoid saturation. The excitation would kill you, but you won't saturate without iron. But iron is like tens of thousands of times a better magnetic "conductor" than just about everything else. Mankind is lucky to have iron. You come up with something better, you'll be a rich man. Regards, Jeff M _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Roger Heuckeroth
Roger Heuckeroth wrote:
> This is interesting. The toque is proportional to the > strength of the magnetic field... correct? So, are we saying > that the strength of the magnetic field starts out as a > squared function of current, and then transitions to a linear > function of current... and this is because of what? Eddy > currents in the iron? Saturation? Right. The field strength is proportional to the field current in a wound field machine. Torque is proportional to armature current times field strength, so torque is proportional to the product of armature current and field current. In a series wound machine, the armature and field current are the same, so torque is proportional to the square of the current. As the field saturates, its strength stops increasing with additional current, so eventually the current will increase only linearly since increasing armature current continues to increase torque. In theory. ;^> If you look at the published data for typical motors used in EVs, you will find that the torque never really increases as the square of the current, even at low currents (e.g. 100A or less). This may be partly due to the fact that the theoretical relationship doesn't take into account that some of the torque is consumed internally (bearings, fan/windage, brush drag) and so the measured shaft torque will be somewhat to much less than expected (since at low currents the shaft speed is high and the losses due to the internal fan will be high). Typically, the available torque seems to increase as a low 1.xth power (i.e. better than linearly, but less than squared) of the current. Most motor data goes out to about 500A, so if you take a couple of points near the upper end of the curve and extrapolate linearly you will have a conservative estimate of the torque available at higher currents. Cheers, Roger. _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
In reply to this post by Jeff Major
----- Original Message ----- From: "Jeff Major" <[hidden email]> To: "Electric Vehicle Discussion List" <[hidden email]> Sent: Monday, July 21, 2008 4:55 PM Subject: Re: [EVDL] motor torque question > Hi Roger, > > A few comments inserted...... > > --- On Mon, 7/21/08, Roger Heuckeroth <[hidden email]> wrote: > >> This is interesting. The toque is proportional to the >> strength of the >> magnetic field... correct? > > The torque is the product of armature current and flux. > >> So, are we saying that the >> strength of the >> magnetic field starts out as a squared function of current, >> and then >> transitions to a linear function of current... and this is >> because of >> what? Eddy currents in the iron? Saturation? > > Saturation. Flux no longer increases but armature current can. > >> I'm just trying to understand this? There was another >> thread on how >> to improve the old tried and true series wound DC motor. >> Sounds like >> different material to avoid saturation would be a good >> idea. > > There are only a few ferromagnetic materials, like iron. All other > materials have basically the permeability of a vacuum. So use wood or > plastic to avoid saturation. The excitation would kill you, but you won't > saturate without iron. But iron is like tens of thousands of times a > better magnetic "conductor" than just about everything else. Mankind is > lucky to have iron. You come up with something better, you'll be a rich > man. > > Regards, > > Jeff M iron field housing on a old forklift motor in Taiwan, 40 years ago.Wasn't worth a damn! NO torque or Power! An E.E.(Chinese guy) told me that AFTER we machined up a new field!Well, ya live and learn, I guess?All physics laws transcend national boundries, anyhow Bob > > > > > _______________________________________________ > For general EVDL support, see http://evdl.org/help/ > For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev > _______________________________________________ For general EVDL support, see http://evdl.org/help/ For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev |
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