Rotational Field From Two Signals - Confirm

Started by Steve Morris January 13, 2018
I want to create a rotational field from two signals. Can someone please 
confirm if this is the correct approach?

Are the coils correctly wired?

See linked diagram below.

https://app.box.com/s/zdlcd624qb3ortyxowk4bnhe4zgs4y8v

Steve Morris
On 13.1.18 13:34, Steve Morris wrote:
> I want to create a rotational field from two signals. Can someone please > confirm if this is the correct approach? > > Are the coils correctly wired? > > See linked diagram below. > > https://app.box.com/s/zdlcd624qb3ortyxowk4bnhe4zgs4y8v > > Steve Morris
For proper rotation, the signals have to go both positive and negative, instead of stopping at zero. -- -TV
On Sat, 13 Jan 2018 15:34:14 +0200, Tauno Voipio
<tauno.voipio@notused.fi.invalid> wrote:

>On 13.1.18 13:34, Steve Morris wrote: >> I want to create a rotational field from two signals. Can someone please >> confirm if this is the correct approach? >> >> Are the coils correctly wired? >> >> See linked diagram below. >> >> https://app.box.com/s/zdlcd624qb3ortyxowk4bnhe4zgs4y8v >> >> Steve Morris > >For proper rotation, the signals have to go both >positive and negative, instead of stopping at zero.
And should be sine waves for smooth rotation. Square waves will make jerky motion, like a stepper motor. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Saturday, 13 January 2018 17:12:30 UTC, John Larkin  wrote:
> On Sat, 13 Jan 2018 15:34:14 +0200, Tauno Voipio > <tauno.voipio@notused.fi.invalid> wrote: > > >On 13.1.18 13:34, Steve Morris wrote: > >> I want to create a rotational field from two signals. Can someone please > >> confirm if this is the correct approach? > >> > >> Are the coils correctly wired? > >> > >> See linked diagram below. > >> > >> https://app.box.com/s/zdlcd624qb3ortyxowk4bnhe4zgs4y8v > >> > >> Steve Morris > > > >For proper rotation, the signals have to go both > >positive and negative, instead of stopping at zero.
in practice they would be, but do they have to be?
> And should be sine waves for smooth rotation. Square waves will make > jerky motion, like a stepper motor.
jerky motion is more like jerky when eaten. NT
On Saturday, January 13, 2018 at 3:34:51 AM UTC-8, Steve Morris wrote:
> I want to create a rotational field from two signals. Can someone please > confirm if this is the correct approach? > > Are the coils correctly wired?
> https://app.box.com/s/zdlcd624qb3ortyxowk4bnhe4zgs4y8v
If the wiring convention of the symbols is what it seems to be, the color paired coils produce same-sense poles (two N poles, then half cycle later, two S poles). That's exactly backward, you want something that will , control a compass as a rotor, so one N and one S pole pointed inward is wanted. Square waves (like for a stepper motor) are relatively inefficient, power-wise, and (as others have noted) pulsed DC isn't desirable. Four drive signals (forward current winding next to reverse current winding) rather than two is the norm for synchronous/stepper motors driven from single DC power supply.
On Sat, 13 Jan 2018 13:44:45 -0800 (PST), tabbypurr@gmail.com wrote:

>On Saturday, 13 January 2018 17:12:30 UTC, John Larkin wrote: >> On Sat, 13 Jan 2018 15:34:14 +0200, Tauno Voipio >> <tauno.voipio@notused.fi.invalid> wrote: >> >> >On 13.1.18 13:34, Steve Morris wrote: >> >> I want to create a rotational field from two signals. Can someone please >> >> confirm if this is the correct approach? >> >> >> >> Are the coils correctly wired? >> >> >> >> See linked diagram below. >> >> >> >> https://app.box.com/s/zdlcd624qb3ortyxowk4bnhe4zgs4y8v >> >> >> >> Steve Morris >> > >> >For proper rotation, the signals have to go both >> >positive and negative, instead of stopping at zero. > >in practice they would be, but do they have to be?
How do you get the other two quadrants? You're just alternating between 0degrees and 90degrees. The typical way of driving this sort of thing is with a full bridge (four switches), so the current can go both directions to get the third and fourth quadrant.
>> And should be sine waves for smooth rotation. Square waves will make >> jerky motion, like a stepper motor. > >jerky motion is more like jerky when eaten. > > >NT
On 13/01/18 22:34, Steve Morris wrote:

I have redrawn based upon my understanding of the comments received. Is 
this now correct?

https://app.box.com/s/dx442zddrrerf2b45tlv3lshjgi04ubb

I want to use only two signals so they can be output via a sound card 
into a bipolar driver.

Steve Morris
On Saturday, January 13, 2018 at 6:42:49 PM UTC-8, Steve Morris wrote:
> On 13/01/18 22:34, Steve Morris wrote: > > I have redrawn based upon my understanding of the comments received. Is > this now correct? > > https://app.box.com/s/dx442zddrrerf2b45tlv3lshjgi04ubb
Yep, that looks like a normal two-phase motor wiring. Torque should be nearly constant at all angles, and (with a permanent magnet rotor) the rotation should be synchronous. It'll be nearly synchronous with a soft-iron rotor (slightly slower, depending on load).
On Sunday, 14 January 2018 01:22:04 UTC, k...@notreal.com  wrote:
> On Sat, 13 Jan 2018 13:44:45 -0800 (PST), tabbypurr wrote: > >On Saturday, 13 January 2018 17:12:30 UTC, John Larkin wrote: > >> On Sat, 13 Jan 2018 15:34:14 +0200, Tauno Voipio > >> <tauno.voipio@notused.fi.invalid> wrote: > >> >On 13.1.18 13:34, Steve Morris wrote:
> >> >> I want to create a rotational field from two signals. Can someone please > >> >> confirm if this is the correct approach? > >> >> > >> >> Are the coils correctly wired? > >> >> > >> >> See linked diagram below. > >> >> > >> >> https://app.box.com/s/zdlcd624qb3ortyxowk4bnhe4zgs4y8v > >> >> > >> >> Steve Morris > >> > > >> >For proper rotation, the signals have to go both > >> >positive and negative, instead of stopping at zero. > > > >in practice they would be, but do they have to be? > > How do you get the other two quadrants? You're just alternating > between 0degrees and 90degrees. The typical way of driving this sort > of thing is with a full bridge (four switches), so the current can go > both directions to get the third and fourth quadrant.
The other 2 quadrants would certainly be nice & sensible, but with just 2 you've still got a moving magnetic field, so I think it would at least turn. NT
>The other 2 quadrants would certainly be nice & sensible, but with just 2 >you've still got a moving magnetic field, so I think it would at least turn.
To get continuous _field_ rotation you need all four quadrants (you need at least 3 phases@120 degrees, but 4@90 works too). Cheers Phil Hobbs