Re: [Emc-users] Resolver to Quadrature Convertor
On 25 April 2010 18:28, RogerN re...@wildblue.net wrote: In your opinion, do you think the Arduino would work to use as an amplifier by using 1 resolver and adding 3 phases of PWM to drive 3 half H-Bridges? Yes. The answer is now a definite yes. In fact since the question was asked about 2 months ago (it seems longer) I have found several ways to do it, but the one that I got going today was a purely Arduino + Power semi system. The Arduino produces a sinusoidal excitation for the Resolver, amplified and low-pass filtered by a power op-amp, the return voltages are measured and decoded into an angle, which is then converted into a Psuedo-Hall sensor pattern and used as the lookup into a commutation table to choose 2 of 6 pins to drive. The 6 pins are taken to a buffer IC which has the enable pin connected to a 20kHz PWM from one of the Arduino PWM generators with a duty cycle based on a third analogue input voltage (I have a speed-pot connected at the moment). The drive PWM is taken to a separate power board consisting of a bridge rectifier and a big capacitor as the DC 300V source, and an IRAMS10UP60A (600V, 10A, £15) driver IC (and a set of opto-isolators). http://docs-europe.origin.electrocomponents.com/webdocs/0dca/0900766b80dca34e.pdf That is basically all there is to it, and it runs the 500W servos like a champ. Very fast and very powerfully. I don't expect to keep it in this configuration, I anticipate keeping the resolver-to-quadrature parts of the Arduino code, taking the quadrature signals into EMC2 and then using one of the Hostmot2 3pwmgens and one of the BLDC motor drivers that have been written for EMC2 HAL in the intervening months. I will keep the power driver and anticipate experimenting with a minimalist setup of just the power driver, quadrature conversion and Parallel port in order to see what the minimum-cost option is and just how poorly it works. On the actual machine I am not sure how I will do it, there is almost an embarassment of options now. -- atp -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
On 26 April 2010 00:58, RogerN re...@wildblue.net wrote: I see brushless servo amps on ebay for reasonable but I think most require hall signals. http://cgi.ebay.com/AMC-brushless-servo-amplifier-BE25A20E-/310165227459?cmd=ViewItempt=BI_Control_Systems_PLCshash=item483749c7c3 I could put the Resolver to Hall signal code up on the Wiki, but I a lot less confident that it is right. Specifically I am not sure which of the zeros of the resolver is considered zero degrees and how the Hall signals typically correspond to that angle. It also needs adjusting for different numbers of motor poles. If you are happy to fiddle with the table that correlates Hall signals to resolver angle then I can publish the Arduino code somewhere. It is something that seems fairly risk-free to tinker with, as the worst-case is that the motor just stalls and vibrates. -- atp -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
- Original Message - From: Andy Pugh a...@andypugh.fsnet.co.uk To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: Monday, April 26, 2010 3:56 AM Subject: Re: [Emc-users] Resolver to Quadrature Convertor On 26 April 2010 00:58, RogerN re...@wildblue.net wrote: I see brushless servo amps on ebay for reasonable but I think most require hall signals. http://cgi.ebay.com/AMC-brushless-servo-amplifier-BE25A20E-/310165227459?cmd=ViewItempt=BI_Control_Systems_PLCshash=item483749c7c3 I could put the Resolver to Hall signal code up on the Wiki, but I a lot less confident that it is right. Specifically I am not sure which of the zeros of the resolver is considered zero degrees and how the Hall signals typically correspond to that angle. It also needs adjusting for different numbers of motor poles. If you are happy to fiddle with the table that correlates Hall signals to resolver angle then I can publish the Arduino code somewhere. It is something that seems fairly risk-free to tinker with, as the worst-case is that the motor just stalls and vibrates. -- atp -- We have a couple different types of setup at work. One we have to loosen the resolver coupler and align to the field, I'm guessing that it puts some holding torque on the field, perhaps rotating a few degrees to make sure it's locked in. The other type you run a setup routine on and it learns the angle and stores in the controller. Taking an educated guess, I would rotate the field like a stepper motor, watch for rotation of the resolver, then rotate the field the other direction monitoring for movement. If the motor isn't under load, perhaps the armature will align up the field good enough for hall signals. When I first got these motors, I wrote a PIC program that output 3 phase PWM SIN wave and ran it like a stepper motor mini-stepping. I made up a 32 byte lookup table and put SIN values (Integer (sin(angle)+1) X 127) so 0 represented -1, 255 represented 1, etc. This value would be output PWM to a Half H-bridge, not a good one but good enough to experiment with. I was only using maybe 20V to the motor, it ran slow but it ran pretty good. Anyway, I think some setup procedure could be implemented to have the amp move and hold the armature, then either learn the angle or align the resolver. Roger Neal -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
On 26 April 2010 00:58, RogerN re...@wildblue.net wrote: I see brushless servo amps on ebay for reasonable but I think most require hall signals. I have put my Hall-sensor emulation code on the Wiki (as a link on the same page). It is happily running my servo upstairs at this moment. There is something odd that unless the speed is set just right it keeps stopping. If I check the Hall signals with it stopped there is a perfectly good Hall code, but there is +30V on all of the motor terminals. I think this is either a peculiar drive fault, or possibly the rather oversized motor for the drive (30V drive, 300V motor) might be latching-up one of the drivers with back-emf (Is this possible? It is purest speculation) http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?ResolverToQuadratureConverter -- atp -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
On 4/25/2010 9:57 AM, Andy Pugh wrote: Firstly let me make it clear that functional, competent, accurate and reliable Resolver to Quadrature convertors are available from Pico Systems and Mesa Electronics: http://pico-systems.com/resolver.html (I can only find a mention of the Mesa 7i49 on the price list, but I understand it does exist) Furthermore there are commercial chips to do the conversion too: http://www.analog.com/en/analog-to-digital-converters/synchroresolver-to-digital-converters/ad2s1200/products/product.html For reasons that I am not clear of myself, I eschewed all such approaches, and decided on a DIY approach, using an Arduino board. I have written it up on the Wiki. http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?ResolverToQuadratureConverter It handles 3 resolver channels and has been tested to 1600 rpm (the max speed of my cordless drill). Bench testing indicates that the quadrature pulses should keep up up to 3750rpm. For higher speeds it would be necessary to run fewer resolver channels. Very nice Andy... Thanks, Dave -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
- Original Message - From: Andy Pugh a...@andypugh.fsnet.co.uk To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: Sunday, April 25, 2010 8:57 AM Subject: [Emc-users] Resolver to Quadrature Convertor Firstly let me make it clear that functional, competent, accurate and reliable Resolver to Quadrature convertors are available from Pico Systems and Mesa Electronics: http://pico-systems.com/resolver.html (I can only find a mention of the Mesa 7i49 on the price list, but I understand it does exist) Furthermore there are commercial chips to do the conversion too: http://www.analog.com/en/analog-to-digital-converters/synchroresolver-to-digital-converters/ad2s1200/products/product.html For reasons that I am not clear of myself, I eschewed all such approaches, and decided on a DIY approach, using an Arduino board. I have written it up on the Wiki. http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?ResolverToQuadratureConverter It handles 3 resolver channels and has been tested to 1600 rpm (the max speed of my cordless drill). Bench testing indicates that the quadrature pulses should keep up up to 3750rpm. For higher speeds it would be necessary to run fewer resolver channels. -- atp -- I have a couple of servo motors I bought surplus, haven't used them mainly because the have resolvers and uses the resolver for commutation. Some day when/if I need to use them the plan was to buy an amp that would work with them. From your project I gather that a home made amp might be do-able reading 1 resolver and driving 3 half H-bridges to control a motor. I'm guessing to figure the timing between the resolver and fields it could be ran open loop like a stepper and record the resolver following angle between forward and reverse. From there perhaps calculate the optimum angle for the field phases to the resolver position. And after all that, give quadrature output for EMC2 to know the position. In your opinion, do you think the Arduino would work to use as an amplifier by using 1 resolver and adding 3 phases of PWM to drive 3 half H-Bridges? Thanks Roger Neal -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
On 25 April 2010 18:28, RogerN re...@wildblue.net wrote: In your opinion, do you think the Arduino would work to use as an amplifier by using 1 resolver and adding 3 phases of PWM to drive 3 half H-Bridges? Possibly, and it is something I have been thinking of looking in to. I am not sure if it is possible to persuade the Arduino PWM drivers to do the complementary low-side driver signals that I think are needed. It might be easier to write a 3-phase PWM comp module for EMC2 to create the driver signals. There is already one in the Hostmot2 software, but it is not currently supported in the EMC2 has drivers. (That might change) What is possible (and I have a version of the Resolver code that already does it) is to synthesise Hall sensor signals to pass to a generic BLDC motor driver. However most BLDC drivers don't handle the voltages that servos are designed to run at. I have made my servos rotate with a generic BLDC driver, but only slowly (lack of voltage / high rotor inductance I think) and only briefly (something odd about the drives, they trip out on overload even with small BLDC motors well within their stated parameters) I am thinking of buying one of these for further experimentation: http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProductR=6880732 Mainly as the package includes shoot-through protection and I don't trust my coding skills. -- atp -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
On 25 April 2010 19:50, Andy Pugh a...@andypugh.fsnet.co.uk wrote: I am thinking of buying one of these for further experimentation: http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProductR=6880732 Mainly as the package includes shoot-through protection Thinking some more about this, the shoot-through protection means that you can just drive the low-side inputs permanently low and apply PWM to the high-sides. I have no idea if that will work. There are 4 PWMs on the Arduino, though two share a timer. The Mega has 14 PWM pins though, so presumably has rather more timers and possibly more options (I have not looked) I think that means that it could be done, but you might run out of CPU calculating the phase angles and duty cycles. -- atp -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Resolver to Quadrature Convertor
- Original Message - From: Andy Pugh a...@andypugh.fsnet.co.uk To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: Sunday, April 25, 2010 1:50 PM Subject: Re: [Emc-users] Resolver to Quadrature Convertor On 25 April 2010 18:28, RogerN re...@wildblue.net wrote: In your opinion, do you think the Arduino would work to use as an amplifier by using 1 resolver and adding 3 phases of PWM to drive 3 half H-Bridges? Possibly, and it is something I have been thinking of looking in to. I am not sure if it is possible to persuade the Arduino PWM drivers to do the complementary low-side driver signals that I think are needed. It might be easier to write a 3-phase PWM comp module for EMC2 to create the driver signals. There is already one in the Hostmot2 software, but it is not currently supported in the EMC2 has drivers. (That might change) What is possible (and I have a version of the Resolver code that already does it) is to synthesise Hall sensor signals to pass to a generic BLDC motor driver. However most BLDC drivers don't handle the voltages that servos are designed to run at. I have made my servos rotate with a generic BLDC driver, but only slowly (lack of voltage / high rotor inductance I think) and only briefly (something odd about the drives, they trip out on overload even with small BLDC motors well within their stated parameters) I am thinking of buying one of these for further experimentation: http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProductR=6880732 Mainly as the package includes shoot-through protection and I don't trust my coding skills. -- atp -- I see brushless servo amps on ebay for reasonable but I think most require hall signals. http://cgi.ebay.com/AMC-brushless-servo-amplifier-BE25A20E-/310165227459?cmd=ViewItempt=BI_Control_Systems_PLCshash=item483749c7c3 I believe the above is 25A (peak, 12.5A continuous) at 200 (maybe 240) Volt, should be good for about 3HP of servo. Also I have seen some amps from Pacific Scientific that work with encoders or resolvers and will give a quadrature encoder out to the controller, I guess that would be a nice all in one solution. RogerN -- ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
