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3 Phase Class D amp for DIY BLDC motor Drive
3 Phase Class D amp for DIY BLDC motor Drive
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Old 17th May 2017, 12:26 PM   #11
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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Interesting work, guy. Good luck.
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Osvaldo F. Zappacosta. Electronic Engineer UTN FRA from 2001.
Argentine Ham Radio LW1DSE since 1987.
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Old 17th May 2017, 12:51 PM   #12
Pyramid is offline Pyramid  United States
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Quote:
Originally Posted by ralphfcooke View Post
You are right Bill, the Papst motors are seriously inefficient, some quote as little as 6%. They are eddy current motors and rely on the magnetic field in the stator to create the field in the external rotor, which then opposes it. One of the advantages in this is the ability for the rotor 'poles' to be curved, producing a totally cogless rotating magnetic field; in conjunction with the three phases this creates a smoothness that I don't believe can be duplicated with any motor using permanent magnets and an iron core, where there is always some tendency to 'snap' to the next position of 'rest'.
I'm not sure how the AA motors do it, but as far as I can tell, there is zero cogging due to variable reluctance that you described.

On the Hurst motors, this is easily detectable by just rotating the shaft. If you short all the wires together, the cogging is really apparent (the motor is acting as an AC generator with a short circuit for a load).

If you do the same test with the AA motors, it is completely smooth, even the 4 pole motor exhibits no cogging.

The other source of vibration in the AC synch motors, is the coils are wound on 2 separate bobbins that are enclosed by the metal pole pieces rotated 1/2 step between the poles. The bobbins can "float" and can cause vibration at the line frequency. The coils in the BLDC motors are wound on stators that are permanently mounted to the case of the motor so the chance for electrical induced vibrations is greatly reduced.
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Old 17th May 2017, 01:20 PM   #13
GaryB is offline GaryB  United States
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3 Phase Class D amp for DIY BLDC motor Drive
Quote:
Originally Posted by Pyramid View Post
. . . suitable for driving a BLWR172S-24-2000 or BLWS231S-24-2000 BLDC motor from Anaheim Automation . . .
Very interesting. I'm tempted to send out an order of boards to try this out. Are there people interested in sharing an Oshpark order? 10 boards are slightly cheaper/board than 3 but take longer.

I'm also curious to know what sort of motor pod people are planning to use. I could talk to a local machinist but I wonder if there are off the shelf stand-alone motor pods that would fit the AA motors.
Thanks,
---Gary
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Old 17th May 2017, 01:44 PM   #14
Pyramid is offline Pyramid  United States
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Quote:
Originally Posted by GaryB View Post
I'm also curious to know what sort of motor pod people are planning to use. I could talk to a local machinist but I wonder if there are off the shelf stand-alone motor pods that would fit the AA motors.
Thanks,
---Gary
The BLWS series is essentially a drop in replacement form factor for the Hurst 59 series motors (what VPI uses in most of their tables), but the flange is thicker material so you would need longer mounting screws.

The BLWR series is smaller diameter but longer length then the Hurst motors. It is too tall to fit in the SAMA housing of a VPI. It also has a 4mm shaft and there are aluminum sleeves available from the RC boat market that convert 4mm shafts to 3/16" props that can be used to fit a VPI 600 RPM pulley.
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Old 17th May 2017, 02:01 PM   #15
Pyramid is offline Pyramid  United States
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Attached is a CAD drawing for a aluminum enclosure I had made at a local machine shop. They charged me ~$60. The case is cut from a solid aluminum billet 4" diameter on a CNC lathe.

The 1/2" NPT opening on the bottom is so the void can be filled with lead (or steel) shot when the motor is installed. There are 1/2" flush plugs available from McMaster Carr and others. The openings on the motor must be covered if you use small diameter shot pellets.

The connection to the motor is done with a 3 pin miniature mic connector. The socket and connector are available on line at https://vetco.net/products/3-pin-min...le-female-pair.
Attached Images
File Type: jpg Motor Housing.JPG (256.2 KB, 562 views)
Attached Files
File Type: pdf Motor Housing.pdf (145.1 KB, 81 views)

Last edited by Pyramid; 17th May 2017 at 02:15 PM.
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Old 17th May 2017, 02:59 PM   #16
rif is offline rif  United States
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3 Phase Class D amp for DIY BLDC motor Drive
Is one of the motors more desirable than the other from a performance perspective?

Also, I know it must have been discussed, I'm sorry for asking , what is the relationship between the sg4 speed setting and shaft rpm? I know the shaft rpm on one of the motors is double compared to the other.
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Old 17th May 2017, 03:13 PM   #17
Pyramid is offline Pyramid  United States
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Quote:
Originally Posted by rif View Post
Is one of the motors more desirable than the other from a performance perspective?

Also, I know it must have been discussed, I'm sorry for asking , what is the relationship between the sg4 speed setting and shaft rpm? I know the shaft rpm on one of the motors is double compared to the other.
Performance-wise the motors are nearly identical. If I had to choose, I would say the BLWS series is very slightly quieter, but the BLWR series might have slightly more torque.

The choice really comes down to which form factor and mounting option works best and which pulley option you choose:

BLWR series: Machine a 4mm center bore pulley or use a 4mm-3/16" sleeve and use an existing pulley.

BLWS series: Machine a " center bore pulley.

If there is anyone with some machining capabilities, the attached file has CAD drawings for 600 RPM pulleys for both 4mm and 1/4" center bores.
Attached Files
File Type: pdf 8900-04-0300.pdf (300.5 KB, 136 views)

Last edited by Pyramid; 17th May 2017 at 03:24 PM.
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Old 17th May 2017, 04:13 PM   #18
chromenuts is offline chromenuts  United States
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Wow!...this came to fruition a lot faster than I thought it might.

You've out done yourself again Bill! A BLDC motor/controller project "in a box"...I can't thank you enough for this. I think it is really an ideal solution for those in the community looking for a better motor/controller upgrade alternative, especially VPI owners like myself.

It has resorted my priorities concerning my motor/controller projects. I already had a couple of the BLWS motors that I ordered "before the rush". I've got 3 of the amp boards and sets of components on there way now. My first goal will be to finish refurbishing and upgrading my old HW19 and adding this BLDC solution to it as a SAMA.

My only issue will be that the ICs I ordered from Twysted last month are v1.02. Since I have at least one 2 phase controller I intend to follow through on, I will most likely offer what I don't think I will use up at cost and just order v1.03 replacements.

My approach for the pulley will be to pop the VPI pulley into my lathe and bore it out to 1/4".
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Old 17th May 2017, 05:16 PM   #19
rsritchey is offline rsritchey
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Quote:
Originally Posted by Pyramid View Post

If there is anyone with some machining capabilities, the attached file has CAD drawings for 600 RPM pulleys for both 4mm and 1/4" center bores.
Can you also attach the CAD files for the pulleys?
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Old 17th May 2017, 05:20 PM   #20
Pyramid is offline Pyramid  United States
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Quote:
Originally Posted by chromenuts View Post
My approach for the pulley will be to pop the VPI pulley into my lathe and bore it out to 1/4".
I'd advise against this. Nearly impossible to keep everything concentric. If you have a lathe, turn a new pulley from scratch and do the center bore in the same operation to keep everything aligned.
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