3 Phase Class D amp for DIY BLDC motor Drive
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

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

 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
 Thread Tools Search this Thread
 10th July 2018, 11:49 PM #331 Pyramid   diyAudio Member     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.
 11th July 2018, 04:52 PM #332 jobst   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...
vgeorge
diyAudio Member

Join Date: Mar 2004
Location: poros island
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
 IMG_20180919_224350.jpg (457.4 KB, 270 views)
__________________
"Without deviations from the norm, progress is not possible" - Frank Zappa

 26th September 2018, 09:46 AM #334 icsaki   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.
 11th October 2018, 06:57 AM #335 icsaki   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?
Pyramid
diyAudio Member

Join Date: May 2006
Location: Behind the Cheddar Curtain
Quote:
 Originally Posted by icsaki 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)

 12th October 2018, 05:20 AM #337 icsaki   diyAudio Member   Join Date: Feb 2005 Location: Phoenix, AZ Thank you Pyramid.
 3rd November 2018, 03:55 PM #338 vgeorge   diyAudio Member     Join Date: Mar 2004 Location: poros island 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
 3rd November 2018, 05:20 PM #339 Pyramid   diyAudio Member     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?
 3rd November 2018, 05:34 PM #340 vgeorge   diyAudio Member     Join Date: Mar 2004 Location: poros island 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

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Room Acoustics & Mods     Music     diyAudio.com Articles     Car Audio     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post Pyramid Analogue Source 733 27th November 2018 01:17 PM Pyramid Analogue Source 324 9th November 2018 05:32 AM Pyramid Analogue Source 238 5th February 2018 03:38 AM iancanada Digital Source 1 21st July 2015 04:51 PM 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.

 Home - Contact Us - Advertise - Rules - diyAudio Store - Sponsors - Privacy Statement - Terms of Service - Top - Opt-out policy

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