Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

3 Phase Class D amp for DIY BLDC motor Drive
3 Phase Class D amp for DIY BLDC motor Drive
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th July 2018, 11:49 PM   #331
Pyramid is offline Pyramid  United States
diyAudio Member
 
Pyramid's Avatar
 
Join Date: May 2006
Location: Behind the Cheddar Curtain
I haven't been able to find a usable formula for 3 phase motors. The closest I remember is a post by Mark Kelly:

Effective load=coil resistance x forward voltage / (forward voltage - back EMF).

I doubt this is accurate for 3 phase.

I've tried modeling something in an Excel spreadsheet, but the results weren't even close to the measurements I was getting and the complexity of the spreadsheet was starting to get unmanageable. I'm sure there are a number of DSP apps that address this, but the math is not trivial.

Probably the most direct approach is the empirical method: Measure the DC current between the power supply and amp driving the motor; multiply by the efficiency of amplifier (~50% for class AB, 90-95% for class D) and the result should give a close approximation of the power consumption of the motor. Adjust the output voltage to keep the power consumption constant at both speeds (or what ever speed you want to run at).

Because the back EMF generated by the motor opposes the drive signal, the impedance of the motor effectively increases with speed so the amplitude of the drive signal must increase accordingly. As you push the speed higher and the drive level increases, you must take care not to stall the motor or the current will suddenly spike as the back EMF disappears completely.
  Reply With Quote
Old 11th July 2018, 04:52 PM   #332
jobst is offline jobst  New Zealand
diyAudio Member
 
Join Date: Jan 2010
Location: Chicago
Thanks for the explanation Pyramid. For some reason (Dunning–Kruger? Domain dependent thinking?) I always assume that things in the electrical world are neatly reducible to theory, with nice analytical solutions. Guess at that point it would no longer be an engineering discipline, and the fun would be over

Maybe I'll try and add a live power display to my unit, as a self-education project...
  Reply With Quote
Old 20th September 2018, 06:08 PM   #333
vgeorge is online now vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
3 Phase Class D amp for DIY BLDC motor Drive
This is my latest setup and I think that I like the 3 belts better than two.
Also this is the second motor I have and if you remember I used to complain a little bit, about noise. This one is almost silent. Go figure.
Attached Images
File Type: jpg IMG_20180919_224350.jpg (457.4 KB, 270 views)
__________________
"Without deviations from the norm, progress is not possible" - Frank Zappa
  Reply With Quote
Old 26th September 2018, 09:46 AM   #334
icsaki is offline icsaki  United States
diyAudio Member
 
Join Date: Feb 2005
Location: Phoenix, AZ
I'm looking for an extra MA-3D PCB. Let me know if you have one. Thx.
  Reply With Quote
Old 11th October 2018, 06:57 AM   #335
icsaki is offline icsaki  United States
diyAudio Member
 
Join Date: Feb 2005
Location: Phoenix, AZ
Thanks Pyramid for making this project available.
I built the SG4, the MA-3D and I'm using a BLWS motor. I'm planning to use them in a Thorens TD 125, but with the current pulley dia (0.738") I need 279RPM/376RPM for 33/45. The frequencies are 9.29Hz/12.54Hz.

What should be the nominal and reduced motor voltages for these RPM values?
  Reply With Quote
Old 11th October 2018, 01:50 PM   #336
Pyramid is offline Pyramid  United States
diyAudio Member
 
Pyramid's Avatar
 
Join Date: May 2006
Location: Behind the Cheddar Curtain
Quote:
Originally Posted by icsaki View Post
Thanks Pyramid for making this project available.
I built the SG4, the MA-3D and I'm using a BLWS motor. I'm planning to use them in a Thorens TD 125, but with the current pulley dia (0.738") I need 279RPM/376RPM for 33/45. The frequencies are 9.29Hz/12.54Hz.

What should be the nominal and reduced motor voltages for these RPM values?
Nominal
9Hz: 7VPP (2.5VMRS)
12Hz: 7.6Hz (2.68VRMS)

Reduced
9Hz: 6VPP (2.14VRMS)
12Hz: 6.58VPP (2.33VRMS)
  Reply With Quote
Old 12th October 2018, 05:20 AM   #337
icsaki is offline icsaki  United States
diyAudio Member
 
Join Date: Feb 2005
Location: Phoenix, AZ
Thank you Pyramid.
  Reply With Quote
Old 3rd November 2018, 03:55 PM   #338
vgeorge is online now vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
3 Phase Class D amp for DIY BLDC motor Drive
Hi Pyramid, I have a question regarding the BLWS231S-24V-2000 motor.
The second motor I got, got nosy also, as my first one. This happened after the frequency of the controller got high up, without me taking note.
Is there anything I can do to fix that or I should buy a third motor?
If the motors are so sensitive, maybe we should have a lower limit on the max frequency from the controller?
__________________
"Without deviations from the norm, progress is not possible" - Frank Zappa
  Reply With Quote
Old 3rd November 2018, 05:20 PM   #339
Pyramid is offline Pyramid  United States
diyAudio Member
 
Pyramid's Avatar
 
Join Date: May 2006
Location: Behind the Cheddar Curtain
vgeorge-

Not sure I understand. Why was the frequency of the SG4 high? It should not damage the motor regardless of which frequency you use. If the motor runs noisy at high frequency, does the noise go away when you return to normal freq?

What are the actual frequencies you are using for 33/45 RPM and at what freq did the motor become noisy?
  Reply With Quote
Old 3rd November 2018, 05:34 PM   #340
vgeorge is online now vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
3 Phase Class D amp for DIY BLDC motor Drive
Frequency of the controller when up to 99hz for some time and did not take notice, due to the rotary encoder getting stuck. When I set the frequency back to 20hz or 27hz for 45 rpm, the motor started to be noisy and this does not change. Maybe there is something else to check in the controller or amplifier?
__________________
"Without deviations from the norm, progress is not possible" - Frank Zappa
  Reply With Quote

Reply


3 Phase Class D amp for DIY BLDC motor DriveHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
DIY 4 Phase Sinewave Generator for Turntable Motor Drive Pyramid Analogue Source 733 27th November 2018 01:17 PM
60 WPC Amplifier for DIY Turntable Motor Drive Pyramid Analogue Source 324 9th November 2018 05:32 AM
3 Phase BLDC motor for turntable use? Pyramid Analogue Source 238 5th February 2018 03:38 AM
BLDC motor upgrade board for CDM9/CDM12 transport or CD player iancanada Digital Source 1 21st July 2015 04:51 PM
Motor to drive platter in DIY Record Cleaning Machine audionut44 Construction Tips 7 10th September 2014 10:26 PM


New To Site? Need Help?

All times are GMT. The time now is 07:18 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki