Re: [Emc-users] BLDC Servo Torque Problem?
Hi Peter, thanks for you reply. Its hard to tell with motor specifications, sometimes they are RMS and sometimes they are DC (for example lots of large BLDC motors are rated 320V which actually means they are 220V AC motors) I see. I'll stick with 24 V for now, the power supply is a 350 W unit. 1. initial rotor alignment (if wrong you will have different torque each direction) I think this is OK, as the motors spin smooth and nice in both directions. 2. Make sure the deadtime is set to 0 It is set to 0 (line 207 of the hal ini: http://restweiss.de/bldc_1.zip). 3. Make sure the PWM rate is set fairly high so you dont get current limiting from ripple current (40KHz is good for 7I39s) PWM frequency (is that PWM rate) is set to 20 kHz, but I tried 40 kHz and it makes no difference. 4. Make sure you have the 7I39 current limit set to 15A and not 7.5A Current is limited (still default setting) but I don't think this is the problem. Using a clampmeter I measure 600 mA max. at stall. 5. If you have problems at high speeds, consider running LinuxCNC master and raising the servo thread rate as high as you can (good MBs can do 4 KHz or better) (linuxcnc master has a patch to BLDC than extrapolates the commutation angle base on velocity so approximately halves the commutation angle error at high speeds) Oh, that's cool feature, but I only need very low speeds - so no need to switch I guess. What's next to investigate? Greetings Flo -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
Hi Andy, I decided to put the system on my desk to investigate the case, this took a while. How are you commutating? The present configuration is 'qh'(use encoder input, use hall sensor input). I didn't override the default commutation setting, so I think its sinusoidal. Here are my config fies: http://restweiss.de/bldc_1.zip See you Flo PS: The set-up, a three rope system: http://restweiss.de/loop_1.jpg -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
On Sat, 29 Mar 2014, Florian Rist wrote: Date: Sat, 29 Mar 2014 23:02:03 +0100 From: Florian Rist fr...@fs.tum.de Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] BLDC Servo Torque Problem? Hi Peter, thanks for you reply. Its hard to tell with motor specifications, sometimes they are RMS and sometimes they are DC (for example lots of large BLDC motors are rated 320V which actually means they are 220V AC motors) I see. I'll stick with 24 V for now, the power supply is a 350 W unit. 1. initial rotor alignment (if wrong you will have different torque each direction) I think this is OK, as the motors spin smooth and nice in both directions. 2. Make sure the deadtime is set to 0 It is set to 0 (line 207 of the hal ini: http://restweiss.de/bldc_1.zip). 3. Make sure the PWM rate is set fairly high so you dont get current limiting from ripple current (40KHz is good for 7I39s) PWM frequency (is that PWM rate) is set to 20 kHz, but I tried 40 kHz and it makes no difference. 4. Make sure you have the 7I39 current limit set to 15A and not 7.5A Current is limited (still default setting) but I don't think this is the problem. Using a clampmeter I measure 600 mA max. at stall. Where did you measure the current? (you may indeed measure 600mA in the power leads with current limiting (7.5A) in the driver) If you see a red LED light on the 7I39, you have reached the current limit Another thing to check is that you have not somehow limited the max PWM value so you are not getting sufficient drive voltage (PWM does not get near 100% or near 0%) 5. If you have problems at high speeds, consider running LinuxCNC master and raising the servo thread rate as high as you can (good MBs can do 4 KHz or better) (linuxcnc master has a patch to BLDC than extrapolates the commutation angle base on velocity so approximately halves the commutation angle error at high speeds) Oh, that's cool feature, but I only need very low speeds - so no need to switch I guess. What's next to investigate? Greetings Flo -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
Hi, an brief update, because my current measurement was wrong. I now used a normal ampere meter (Flue 87V) and measured a maximum current of 3.5 A. (I commanded the motor to a position where the phase I observed was at maximum current under low load and than increased the load until the motor stalled. I hope this makes sense.) But still not close to the current limit. See you Flo -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
Hi Peter Where did you measure the current? I measured one phase. (you may indeed measure 600mA in the power leads with current limiting (7.5A) in the driver) The 600 mA was mistake, current reaches 3.5 A actually. If you see a red LED light on the 7I39, you have reached the current limit Oh, in deed it dose light up, it flickers a bit, though. I'll pull the current limit jumper and report back. Thanks. Another thing to check is that you have not somehow limited the max PWM value so you are not getting sufficient drive voltage (PWM does not get near 100% or near 0%) This would be done using hal scope, right? I'll try that. See you Flo -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
On 29 Mar 2014, at 22:08, Florian Rist fr...@fs.tum.de wrote: How are you commutating? The present configuration is 'qh'(use encoder input, use hall sensor input). I didn't override the default commutation setting, so I think its sinusoidal. It is probably worth checking that it works properly in plain h mode as a test that the hall pattern is correct. But the 600mA at stall looks like the real issue. -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
Hi Andy It is probably worth checking that it works properly in plain h mode as a test that the hall pattern is correct. I'll try. What would be the best setting? The drivers have 3 hall sensors and a 4000 CPR encoder with index. But the 600mA at stall looks like the real issue. No, this was my mistake, I just took a reading somewhere without thinking, the correct maximum is 3.5 A. Greeting Flo -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
On 29 March 2014 23:17, Florian Rist fr...@fs.tum.de wrote: What would be the best setting? The drivers have 3 hall sensors and a 4000 CPR encoder with index. qh is almost certainly the best. You could try qhi if, and only if, you are sure of the index pulse orientation. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
Hi Peter, I'll pull the current limit jumper and report back. Thanks. OK, now the jumper are moved from left to right and I reached 6 A max. on one phase. Better. Torque does not feel much stronger though. And the over current LED still light up. But now the current limit is protecting the driver. The drive does not feel very stiff, I can rotate it about 10° maybe 20° before the maximum current is reached. This is a PID settings issue, right? See you Flo -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
Hi Andy qh is almost certainly the best. You could try qhi if, and only if, you are sure of the index pulse orientation. I don't know the orientation aka offset, but I tried to measure it, by observing the index signal, the encoder counter and the hall sensors in hal scope. I think I got it right but it doesn't help. See you Flo -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
On 27 March 2014 17:31, Florian Rist fr...@fs.tum.de wrote: Mesa 7i39-LV Nanotec DB57L01 + 4000 CPR endoder How are you commutating? -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] BLDC Servo Torque Problem?
On Thu, 27 Mar 2014, Florian Rist wrote: Date: Thu, 27 Mar 2014 18:31:12 +0100 From: Florian Rist fr...@fs.tum.de Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: [Emc-users] BLDC Servo Torque Problem? Hi, I have some problems in setting up BLDC servos, I just don't manage to get enough torque. Here's the set-up: Intel D525MW Mesa 5i23 Mesa 7i39-LV Nanotec DB57L01 + 4000 CPR endoder The servos are rated 24V DC, 4.6A (peak 17A). My power supply is 24V DC SNT rated at 500W. I suppose I just don't get the PID settings right, but before investigating this a question regarding power supply: Is the 24V supply correct? Or do I misread the BLDC data sheet and the 24V is a RMS rating? cu Flo The 7I39LV is limited to 30VDC max Its hard to tell with motor specifications, sometimes they are RMS and sometimes they are DC (for example lots of large BLDC motors are rated 320V which actually means they are 220V AC motors) If you dont have enough torque, a couple things to check are 1. initial rotor alignment (if wrong you will have different torque each direction) 2. Make sure the deadtime is set to 0 3. Make sure the PWM rate is set fairly high so you dont get current limiting from ripple current (40KHz is good for 7I39s) 4. Make sure you have the 7I39 current limit set to 15A and not 7.5A 5. If you have problems at high speeds, consider running LinuxCNC master and raising the servo thread rate as high as you can (good MBs can do 4 KHz or better) (linuxcnc master has a patch to BLDC than extrapolates the commutation angle base on velocity so approximately halves the commutation angle error at high speeds) -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
