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  #1  
Old Mon 15 February 2010, 05:27
saas
Just call me: saas
 
ceje
Slovenia
Trying to pick alternate motors

Simply I can not believe that there is no other engine except PK296A2A ..
PK ... is definitely too expensive ..
Perhaps it is better to buy cheaper and better quality to replace them later ..
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  #2  
Old Mon 15 February 2010, 05:51
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
There are many other Motor combinations for the MechMate. Take a look in the motors thread and see.

The only real thing you need to stick to is the NEMA34 type motor.
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  #3  
Old Mon 15 February 2010, 05:52
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
A lot of folks uses the 7.2 Geared motor because there is a good bit of documentation on them in the forum.

Look up threads on Belt Drives and you'll see some different motor.
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  #4  
Old Mon 15 February 2010, 06:22
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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Saas,

I use the motionking (34hs 9801) steppers dierect drive and a couple of others do to with success, you can later build a nice 3.1 belt reduction for it.

Ries
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  #5  
Old Mon 15 February 2010, 06:44
saas
Just call me: saas
 
ceje
Slovenia
..ah, I agree

I have 300VA, 25V +25 V power supply, Gecko 203v, PMDX 122 and PMDX 135-80

On MM mainly on the recommendation 34HS9801 but for 300V power supply may be responsible to me 34HS 9803

I can not discover, what is the difference between 34HS9801, 9802, 9803
the purpose, structure, or ...
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  #6  
Old Mon 15 February 2010, 07:18
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
Send a message via MSN to riesvantwisk Send a message via Skype™ to riesvantwisk
Saas,

see this : http://www.mechmate.com/Forum/messages/15/3326.html

The 9803 was not advised by Maris (from Geckodrive) and I think because of the high inductance of 8.6mH, then you would need to run it at max : sqrt(8.1)*32=93Volt. The gecko 203V can only run till 80V, your power supply in series would give you 70V

The 9802 are rated at max : sqrt(2.4)*32=50V, when your power supply is set parallel will give you sqrt(2)*25=35V, this also seems like a big difference.

Both combinations don't give me a warm fuzzy good feeling of the correct combination of power supply vs stepper motor.

Other Options:
34HS4801 max Voltage : sqrt(5.5)*32=75V
It's a slighly bigger engine only and might work, I don't know if the engine is to big.

34HS8803 max Voltage : sqrt(5.6)*32=76V
slightly smaller engine so you might need a belt drive to run your machine (others will know).

I don't have enough experience and knowledge to give you solid advice, may be somebody else could chime in and let us know the preference between the options. Motion King Specs

Ries
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  #7  
Old Wed 17 February 2010, 11:17
saas
Just call me: saas
 
ceje
Slovenia
I have 300VA, 25V +25 V power supply, Gecko 203v, PMDX 122 and PMDX 135-80

nema34.JPG

please, give me a tip that the engine would suit me
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  #8  
Old Wed 17 February 2010, 11:36
lumberjack_jeff
Just call me: Jeff #31
 
Montesano, WA
United States of America
25v is an optimum power supply for a motor with an impedance of 0.61mH. The power supply can be used with motors of higher impedance, but with a loss in max torque.

I use Fulling FL86STH80-4208 steppers. They work fine with my homebuilt 57v power supply. With a 7.5:1 gear reduction they have ample torque. More than enough to break 1/4" carbide router bits.

I would not recommend the 7.5:1 gearbox, too much backlash. I suspect they'd be okay direct driven, but plan on adding a 3:1 timing belt reduction.

http://www.fullingmotor.com/jsp/productshow.do?id=164

Last edited by lumberjack_jeff; Wed 17 February 2010 at 11:40..
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  #9  
Old Wed 17 February 2010, 13:33
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
From the list that you posted, only the SB85A002 and the SB85B004 look good to me.

The A002 has about 300 oz*in of torque, so you would need a 3:1 to 4:1 belt-drive transmission to have enough torque. At 4.4mH, it could use a power supply voltage of up to 67VDC. (Your 25 + 25 will give you about 35VDC when wired in parallel and about 70VDC when wired in series.) I would wire it in parallel. Even though 35VDC is much less than 67VDC, you should be able to run the motor at 600 RPM, which would move an axis (geared 3:1 with a 1.25" diameter spur gear) at 13 inches per second and over 9 inches per second if geared 4:1.

The B004 has 2X the torque, so you could run it without a belt-drive, but resolution would suffer. It has an inductance rating of 6.5mH, so you would wire the transformer in series.

[Remember that you multiply the AC voltage by the Square Root of 2 to find the DC voltage, i.e., 25 * SQRT(2) = about 35VDC and 50 * SQRT(2) = about 70VDC. There is about a 1V drop because of the diode junction in the bridge rectifier. Also, if your input power is not exactly 115VAC (or 230VAC if you've wired the input side of the transformer in series), then the output voltage will be higher or lower.]
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  #10  
Old Sat 20 February 2010, 23:26
cordell
Just call me: cordell
 
johnson city,tn
United States of America
hello, been looking for motors, keling willl be 60 days, came across these, http://www.circuitspecialists.com/prod.itml/icOid/8930 and was wondering if anyone has any experience or opinion on these motors. I believe they are 8 wire motors with the specs listing series wiring, maybe wrong, any help woud be appreciated, thanks
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  #11  
Old Sun 21 February 2010, 07:07
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
Cordell,

What motors are you looking at?

KL34H260-60-4A

These are a good motor for Belt Drive setups and are 4 wire motors so they are easy to wire up.

I checked this morning and John said he has them in stock.

Mike
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  #12  
Old Sun 21 February 2010, 09:05
lumberjack_jeff
Just call me: Jeff #31
 
Montesano, WA
United States of America
The spec sheet linked to that page indicates that the inductance is 12.

The inductance determines the optimum voltage required. The "Mariss formula" is V=sqrt(I)*32. Thus, sqrt(12)*32=110v

Gecko drives have a max voltage of 70. You could run the steppers on lower voltage, but you'll get less torque.

I would not choose these.

I've been considering these as part of a belt-drive upgrade.

86hs9801
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  #13  
Old Sun 21 February 2010, 09:19
cordell
Just call me: cordell
 
johnson city,tn
United States of America
thanks Mike, for your time and effort, they do have those in stock, I am wanting something in the 600 oz range with the eight wire option, like KL34H280-45-8A , which is being advertised in stock, and is 60 days out, according to John thru mail. didnt come here to bash keling, would gladly buy from them if they had what I wanted, looking for opinions on http://www.circuitspecialists.com/prod.itml/icOid/8930 these motors, which seem to be reasonably priced
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  #14  
Old Sun 21 February 2010, 09:24
cordell
Just call me: cordell
 
johnson city,tn
United States of America
Quote:
Originally Posted by lumberjack_jeff View Post
The spec sheet linked to that page indicates that the inductance is 12.

The inductance determines the optimum voltage required. The "Mariss formula" is V=sqrt(I)*32. Thus, sqrt(12)*32=110v

Gecko drives have a max voltage of 70. You could run the steppers on lower voltage, but you'll get less torque.

I would not choose these.

I've been considering these as part of a belt-drive upgrade.

86hs9801
can you tell from the spec sheet which way it is wired, series ,unipolar , parallel, if this spec sheet is in series,and from looking at other data unipolar and parallel wiring is about 1/4 of the 12mh , some where around three, that should be in the ball park, guess I should have contacted them before posting, just hard to get answer over the weekend, thanks for your reply Jeff

Last edited by cordell; Sun 21 February 2010 at 09:40.. Reason: addition to answer
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  #15  
Old Sun 21 February 2010, 11:36
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
I ran some tests with the Oriental Motor PK299-02AA motor and the Gecko G540 stepper driver. At first glance, it looks like that motor and that driver would not be a good match, but testing showed that it is almost a perfect match for a CNC router.

The G540 uses Gecko's G250 module. That module is limited to motors pulling 3.5A or less. It also uses components that limit the usable voltage to 50VDC or less.

The PK299-02AA pulls up to 3A and has 6mH inductance. Because of the inductance, the "ideal" voltage for that motor is: 32 X SQRT(6) = 78VDC, much higher than the voltage allowed by the G250/G540.

Because of the voltage mismatch, I had never considered using that motor with the low cost G250 module. What a mistake! The G250/G540 can easily drive the PK299-02AA motor at 1,000 RPM, which is faster than it will ever need to go on a CNC machine. With a 4:1 belt drive and a 1.5-inch diameter pinion gear (30-tooth), 1,000 RPM would push an axis at 21 inches per second.

The PK299-02AA motor costs about $210 each. It's little brother, the PK296-02AA costs about $138. I'm sure that Keling has some suitable motors. Pick a motor that requires NO MORE than 3.5A. If the motor has six or eight leads, pick a motor that has a Unipolar rating less than 6.5mH inductance. If the motor is rated 3mH or higher, you can probably use a 50VDC power supply without overheating the motor. If the motor is rated less than 3mH, you'll need to use the formula to find the maximum allowed voltage, i.e., 32 X SQRT(Inducance) = MAX voltage.

Sometimes we get hung up on finding the 'ideal' motor / stepper driver combination instead of using a good motor and a good stepper driver. Most of the time my Shopbot PRT-Alpha is just plodding along at 5-ips, although it can run much faster. The work that I do is best done at 5-ips or even slower. The $1,700 motor/driver (retail price) on my machine offers nothing at a $225 motor/driver could not do equally well.
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  #16  
Old Sun 21 February 2010, 11:54
cordell
Just call me: cordell
 
johnson city,tn
United States of America
Mike ,would you care to take a look at these specs and give you thoughts, http://www.circuitspecialists.com/pr...YGH450B-03.pdf ,this is a 8 wire motor, I believe, and if the spec are in series wiring, would the 12mh inductance be less in unipolar and parallel. Saas, I appoligize for jumping in on your thread, seem like a good place, trying to pick alternate motors, trying to save space.

Last edited by cordell; Sun 21 February 2010 at 12:07..
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  #17  
Old Sun 21 February 2010, 14:33
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Cordell,
I've found that if only one set of specifications are given for a motor, that traditionally that spec is the Unipolar rating.

I compared the ratings for the 85YGH450B-03 to a list of Oriental Motor stepper motors. The closest match was with the PK299-01AA motor when wired unipolar.

The 85YGH450B-03 is rated:
Voltage = 6V
Current = 2A
Inductance = 12mH
Resistance = 3 ohms
Torque = 48 kg*cm ( about 660 oz*in)

The PK299-03AA (unipolar):
Voltage = 6.4V
Current = 2A
Inductance = 14mH
Resistance = 3.2 ohms
Torque = 620 oz*in (about 45 kg*cm)

I'm guessing that the 85YG450B-03 motor would not be an ideal choice if you use a Geckodrive stepper driver. It would require about 120VDC to run at it's maximum voltage and the Geckodrive only allows 80VDC. However, using a G201x, G202 or G203v stepper driver at 80VDC would allow the motor to run at about 66% of its full speed. That might be fast enough for your application.
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  #18  
Old Sun 21 February 2010, 14:43
cordell
Just call me: cordell
 
johnson city,tn
United States of America
thanks mike, buy looking at the specs can you tell me the mh,if wired bipolar parallel? I am assuming it can be with 8 leads or am I wrong in thinking this? by looking at there recommended drivers to use, the low end is 40v, and the upper end is 70volts, so confusing.

Last edited by cordell; Sun 21 February 2010 at 15:05..
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  #19  
Old Sun 21 February 2010, 15:30
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Cordell,

The inductance rating is the same if the motor is wired half-coil (Unipolar) or bipolar parallel. It is 4X higher if the motor is wired bipolar series. (Technically, Unipolar is not the same as half-coil, but the inductance is the same.)

There is a relationship between bipolar parallel, series and half-coil:

Bipolar parallel and bipolar series have equal torque. Half-coil has 1 / sqrt(2) or 70.71% as much torque.

Bipolar parallel and half-coil have the same inductance. Bipolar series has 4X the inductance.

Bipolar parallel pulls 2X more amps than bipolar series. Half-coil pulls 70.71% of the amps of parallel.

Half-coil has 2X the resistance of parallel. Series has 4X the resistance of parallel.

One factor that is not always clear is that if a motor is wired series, it will have the same torque as a motor wired bipolar parallel, but the series motor only performs well at relatively slow speeds. Because of the inductance factor, a series connected motor can't respond as quickly to electrical change as a motor wired half-coil or bipolar parallel. (Inductance is similar to resistance which means that high inductance resists a change in current.)

Also, keep in mind that heat is a factor. Bipolar parallel is hottest. Half-coil is cooler than parallel. Series is cooler than half-coil. Of course, pushing more voltage through a series motor or a half-coil motor will cause the temperature to rise.

If you're familiar with electronics, just looking at an eight wire motor will show why those relationships exist between the different ways of connecting a motor. But if electronics is a mystery, don't worry; the formulas have been tested and everything works as described.

All of those figures make selecting a motor and a driver a little confusing; however, if you look through the forum and pick a motor and a driver that someone else has already used, you will (probably) be safe.

When a minimum and a maximum voltage are given, that usually means the the stepper driver requires the minimum voltage to work properly and it usually means that the stepper motor will overheat if the maximum voltage is exceeded.
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  #20  
Old Sun 21 February 2010, 17:29
cordell
Just call me: cordell
 
johnson city,tn
United States of America
Mike , thank you for that precise lesson on stepper motors, I have a clearer picture and understanding now, lets go shopping!
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  #21  
Old Sun 21 February 2010, 19:40
swatkins
Just call me: Steve
 
Houston
United States of America
Hi Mike.

It's really good to see you posting again!

When I first started looking into this project I was wanting to use the G540 instead of the 203V's.. Because others have had good results using this motor http://www.kelinginc.net/KL34H265-60-4B.pdf I resigned myself to using the 203's.

Your posting about looking at motors that seemed to be a mismatch got me thinking about the G540 again , darn you

Could you take a look at this motor and see if it's possible to run the G540?
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  #22  
Old Sun 21 February 2010, 20:20
shaper
Just call me: Jed
 
Perth, WA
Australia
Steve

I'm certainly no expert and have less testing experience than Mike but I'd suggest looking at the link you attached that there are better options out there for the G540. While the inductance looks similar to the motors Mike was discussing the rated current is significantly outside the capability of the G540 (rated current for motor is 6A while rated current for G540 is 3.5A). There are a few motors out there that would be a reasonable match outside of the tried and true OM7.2's, keep looking you'll find something.
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  #23  
Old Sun 21 February 2010, 20:26
swatkins
Just call me: Steve
 
Houston
United States of America
Quote:
Originally Posted by shaper View Post
Steve

I'm certainly no expert and have less testing experience than Mike but I'd suggest looking at the link you attached that there are better options out there for the G540. While the inductance looks similar to the motors Mike was discussing the rated current is significantly outside the capability of the G540 (rated current for motor is 6A while rated current for G540 is 3.5A). There are a few motors out there that would be a reasonable match outside of the tried and true OM7.2's, keep looking you'll find something.
Hi Jed.


After seeing the good results others have had using this motor and a belt reduction I purchased them.. I resigned myself to using the 203's and a 51 volt power supply because that is the setup they have had excellent results with... So I have the motors already...Just need to go the next step and pick up the drivers...
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  #24  
Old Mon 22 February 2010, 03:36
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
I agree with Jed about the the KL34H265-60-4B. In a perfect world, it would require a 78VDC power supply and a stepper driver that could handle 6A. That motor is rated at 465 oz*in so cutting the current in half would also greatly reduce the torque. (My rule of thumb is that Amps mostly affects the motor's torque and Voltage mostly affects the motor's speed.)

Geckodrive just released the G201x stepper driver. It costs $114 each instead of the $147 of the G203v. The G203v has extra self-protection features that make it almost immune from careless wiring, but the G201x is a much better design than the older G201 and G202 stepper drivers. I haven't tested it yet, so I'm relying 100% on Mariss' data sheet. (He's proven to be 100% dependable in the past.) The G201x can handle motors up to 7A and voltages up to 80VDC. The G201x is the least expensive of the Gecko stepper drivers that can source enough current for your motors.

One of the things that we sometimes gloss over is that most stepper drivers automatically reduce current to the motor greatly when they are idle. That causes the motor's holding torque to also be reduced. (If the stepper driver did not have automatic current reduction, you would have to use massive heat sinks on the stepper driver and probably on the stepper motor.)

My Shopbot PRT-Alpha was originally equipped with 600 oz*in motors and no gearing. Those motors produced plenty of torque so that I didn't have to worry about missed steps under most conditions; however, I quickly learned that the 'Alpha' mode feature that allowed the motors to automatically recover from missed steps was mostly an advertising gimmick. Stalling a motor almost always left a 'divot' in the cut. When I installed 3:1 belt drives on those motors, the first thing that I noticed was vastly reduced 'chatter' in the cuts. Because I had to use a different step (pulse) multiplier, the 3:1 belt drive only produced 1.5X better resolution. The chatter reduction as much greater than just 1.5X better. As nearly as I can tell, the chatter reduction as due to the increased holding torque produced by the belt-drives. Instead of having motors that produced 600 oz*in of torque, the belt-drives allowed the motors to produce 1,800 oz*in of torque. Even in reduced current mode, the motors produced about 900 oz*in of torque. The greater torque seemed to be sufficient to hold an idle axis in place against the forces of the other active axes.

That's a long sermon to explain why you don't want to reduce a motor's torque by starving the motor for current. You could use the G540 with those motors, and if you used a 3.5K 1/4W current limiting resistor, the motors would be limited to 3.5A, but that would also make those motors perform more like a 23-size motor instead of a 34-size motor.

In other words, spending $300 for the G540 is a real bargain if it allows the motors to run at full torque and sufficient speed for the application. To get full torque from your motors, you could buy four of the G201x stepper drivers for $456 or $588 for four G203v stepper drivers.

On my test bench, I have four G202 stepper drivers, ten G203v stepper drivers and one G540. When properly matched with appropriate motors, all of the stepper drivers work equally well. I'll add some G201x stepper drivers when finances allow.
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  #25  
Old Mon 22 February 2010, 13:09
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
I have one doubt, take for example these two motors:

KL34H260-60-4A Bipolar/1.7mH impedance/ $79
KL34H280-55-4A Bipolar/4mH impedance/$89

From the price standpoint there is almost no difference. These will be used with a gecko 203v

1st one power supply should be per Mariss calculations 42V and the second one should be 64V

Besides power supplies voltage/current availability, is there something else that makes one more desirable than the other?

For the ones with 42V supply calculated are 48V too much?

Thanks

Last edited by PEU; Mon 22 February 2010 at 13:12..
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  #26  
Old Mon 22 February 2010, 13:47
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Keep in mind that the formula that Mariss gives is the MAXIMUM voltage for the motor to keep the motor at 80C or less. If you exceed the MAXIMUM voltage, the motor will still run, but it will run too hot and its life expectancy will be shorter.

Even when you use the formula (32 X SQRT( Inductance ) = MAXIMUM Voltage), keep in mind that not all motors are the same. Some manufacturers seem to pluck inductance ratings out of the air. Others try to fit a motor into a certain specification so that it matches other popular motors.

Until you have personally tested a motor, assume that the voltage given by the formula is the absolute maximum that can be used with that motor.
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  #27  
Old Mon 22 February 2010, 23:38
saas
Just call me: saas
 
ceje
Slovenia
I have the 300V, 25V +25 V, 12A Power Supply

Serial connection = 300V, 50V, 6A
Parallel connection = 300V, 25V, 24A

If I have SH85A002 engine 3A is thus 4 * 3A = 12A = 4.4mH and
sqrt4.4 * 32 = 67VDC
SH85A004 is 3.5 and therefore 4 * 3.5 A = 14A and 6.5 mH =
sqrt6, 5 * 32 = 81.5 VDC

Richards,

How do I choose SH85A004 engine when my power supply in the series has only 6A or 6 / 4 = 1.5 A per motor?
We think that is enough for 70VDC calculated 81.5 VDC
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  #28  
Old Tue 23 February 2010, 02:33
KenC
Just call me: Ken
 
Klang
Malaysia
Saas,
Careful not to get suck into achieving "ideal" matching.

The calculations INDICATEs the value that you can use, sometimes, some motor can handle higher or lower value, but you wouldn't know until you have them. INDICATE as its means give a close enough approximation to use safely.
A rational approach is to use the calculated numbers as INDICATOR to avoid making smoke when you wire them out.
It is also perfectly acceptable to run your motors at lower wattage that it "supposed" to handle, gives an extra safety operation margin.
IF you MUST have all the numbers of all the components to "match-up" PERFECTLY, you need to search for a lot more motors & do the evaluation over & over again & again.... ALSO, do not assume the numbers quoted in the catalog, they do have a tolerance range too, so, be careful.
Again, you should scrutinies the numbers but don't get over exited over them.
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  #29  
Old Tue 23 February 2010, 04:16
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
yup, for example, kelling motors have a +- 20% tolerance on their specs sheets... no calculation can be precise from there
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  #30  
Old Tue 23 February 2010, 04:41
KenC
Just call me: Ken
 
Klang
Malaysia
Also, it is normal for transformer to have +- 10% variance, on top of that most power line with +-20% variance is good acceptable standard the world over.... these are only some of the variance I know, there could be more...
To confuse you further, the impedance due to coil inductance is frequency dependent.... i.e. the coil impedance will increase proportional to the pulse rate.... you never know when you hit the "sweet spot" without elaborate measurements... AND every motor has unique signature, even though they look close enough.

Do you see your effort for a "perfect match" will turn futile...
To me, particular in this scenario, "close-enuf" is "good-enuf"

Relax, take a step back, have a day rest & come back for more reading, before you place your order.

BTW, regarding you transformer rating, 300VA is "enuf", more is better, & 999kVA is even better, tranny are never too small as long as you have the cash to splurge & the space to house it. Its your choice.
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