Difference between revisions of "Projets:Perso:2012:controleurfauteuil"
(an) |
(→Répones de spécialistes de fauteuils roulants électriques) |
||
| (11 intermediate revisions by 2 users not shown) | |||
| Line 1: | Line 1: | ||
| − | + | english version here http://wiki.electrolab.fr/Projets:Perso:2012:controler | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | == Problématique== | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| + | Il s'agit ici de trouver une solution au problème technique le plus important dans le foot fauteuil, la "chauffe", ou le fait que les fauteuils les plus sollicités ne peuvent pas tenir plus d'un match sans voir leur performances diminuer de façon importante. | ||
| − | + | L'hypothèse retenue pour l'instant pour expliquer la "chauffe" est la montée en température du contrôleur, qui met le fauteuil en sécurité et ralentit ses capacités : cela doit être vérifié. | |
| − | + | ||
| − | + | ||
| − | + | Nous utilisons des moteurs de 400W avec des contrôleurs de 2X80A. L'électronique est de marque Néo Zélandaise, Dynamic controls, spécialiste de l'électronique de fauteuil roulant. | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ==Contrôleur moteur== | |
| − | + | ||
| − | + | ||
| − | + | ===Audit du sous-ensemble === | |
| − | + | ||
| − | |||
| − | |||
| + | - 2 demi ponts à mosfets composé chacun de 8 transistors. | ||
| + | - mesure de courant par sonde de courant "DC" | ||
| − | + | [complétez] | |
| − | - nous avons des | + | |
| − | - | + | ===Analyse du comportement du contrôleur en situation === |
| + | |||
| + | La première idée que nous avions eu est d'ausculter le comportement du fauteuil en situation réelle (lors d'un match) pour comprendre ce qui se passe. | ||
| + | |||
| + | Cela consiste à mesurer concomittament des grandeurs physiques telle que la tension batterie, le courant batterie et la température du contrôleur moteur. | ||
| + | |||
| + | ====Mesure de températures==== | ||
| + | Un thermocouple est à disposition mais la centrale d'acquisition qu'il est prévu d'utiliser accepte aussi les PT100 et les RTD. | ||
| + | http://www.omega.com/prodinfo/rtd.html | ||
| + | On peut aussi prendre un capteur silicium genre KTY81-121 avec R25 = 990 Ohms et qui varie de 700 Ohms entre 20 et 100°C Tmax = 150°C : un coup de tableur permet de convertir en température. | ||
| + | |||
| + | ====Mesure de courant==== | ||
| + | Shunt 200A dispo | ||
| + | |||
| + | ====Autres mesures==== | ||
| + | La centrale d'acquisition qu'il est prévu d'utiliser dispose de nombreux canaux (20 voies de mesure voire plus), il est possible de faire des mesures simultanées plus étendues que celles évoquées ci-avant. Par exemple, on peut faire plusieurs mesures de températures sur le contrôleur, sur les moteurs, tension équivalente des PWM, etc. | ||
| + | |||
| + | ====Acquisition en situation==== | ||
| + | L'alim de la centrale d'acquisition est "à transformateur" sur 230V : on peut mettre un petit onduleur 150VA pour faire le 230V sur le fauteuil : | ||
| + | mais l'onduleur dispo fait du carré, donc pas simple. | ||
| + | |||
| + | Quatre orientations: | ||
| + | # soit ça passe avec le 230V carré (= voir si le transfo s'échauffe pas trop, sachant qu'un essai dure 10 minutes) | ||
| + | # soit on filtre le carré, mais faire un filtre 50Hz qui coupe assez raide vers 70Hz est une véritable gageuse | ||
| + | # soit on trouve un petit onduleur sinus | ||
| + | # soit, on se limite à 2 canaux (tension batterie, température contrôleur), et dans ce cas un scope portable sur batterie fera l'affaire. | ||
| + | Un oscillo ne mesurant que des tensions, il faut utiliser un convertisseur thermocouple -> tension/courant ou PT100 -> tension/courant [dispo] pour faciliter l'enregistrement des données de température. Exemple d'un utre convertisseur température-tension avec sa sonde : http://www.gsamart.com/webdata/prodimg/FLU_e0007903_lg.jpg | ||
| + | |||
| + | ===Possibilité de faire évoluer le contrôleur moteur === | ||
| + | Quelques questions en suspens pour le moment : | ||
| + | # Est ce vraiment le contrôleur qui provoque la chauffe? (la réponse doit venir de l'audit en situation) | ||
| + | # nous avons des contrôleurs de 60A, est il possible de les passer "facilement" à 80A (économie importante à réaliser)? | ||
| + | |||
| + | |||
| + | ==Réponses de spécialistes de fauteuils roulants électriques== | ||
| + | Ce projet a été posté (en anglais) sur un forum spécialisé sur les fauteuils roulants électriques, voici ci dessous deux de leurs réponses : | ||
| + | |||
| + | ===1=== | ||
| + | |||
| + | ''I also suggest that your friends download the DX System manual, and all other DX and DX2 manuals as well. They will, for example, already find that temp foldback (1) does respond to power module temperature, and (2) does reduce output. In other words, some of their questions are already answered. Moreover, they will discover that the foldback parameters are programmable and, by default, are pretty conservative. A slight increase in the temp for foldback could give a lot more playing time before foldback without actually risking the controller. Undoubtedly, JoeC will come along to tell you what he uses on his wife's soccer chair. He will also probably describe how he's used some small fans to improve heat dissipation. With the manuals, an OEM programming dongle and a PC you will at least know what temp has been programmed; even the cheapest commercial grade components have a temp limit of 80oC, and better components have temp limits quite a bit higher. So a foldback setting of say 60o is certainly giving you a huge safety margin. You probably should have some buffer as the temp sensor isn't necessarily at the hottest spot in the module, but a 20oC margin, assuming cheap components, is surely more than's needed to protect the module. Of course, you may find that avoiding PM foldback also leads to the motors getting rather hot - JoeC should again be able to bring the sound voice of experience to bear. | ||
| + | |||
| + | ''Lastly, there was some mention here that the difference between 60A and 90A PM's is just some on-board connections or passive components. I've never seen confirmation of this, though I suspect that it makes sense for Dynamic to use the same MOSFETs in all PM variants. If that's true, perhaps your friends can discover what needs to be changed.'' | ||
| + | |||
| + | Ciao, | ||
| + | Lenny | ||
| + | |||
| + | ===2=== | ||
| + | |||
| + | ''To answer simply, here are replies to your questions: | ||
| + | |||
| + | ''1- Yes, it really is the temperature of the controller that causes the chair performance to be decreased. Keep the controller cool, and it will not reduce its output. | ||
| + | |||
| + | ''2- What to do? Reprogram it to a higher value, and it will be able to work harder. I have reprogrammed these controllers to a maximum temperature of 85C, from the stock value of (I think) 60C. I have used fans blowing on the controllers, and this helps. I have mounted the controller on a flat aluminum plate, and this helped a little, but not as much as fans, reprogramming, and moving the controller to a space where it can get free air flow. | ||
| + | |||
| + | ''3- Can you convert 60A DX2 to 90A? Probably not. As the design sophistication and manufacturing control is improved, they are less likely to overbuild the controllers, and more likely to have diagnostic self checking at power-on that will detect and object to any tweaks. If they are older than DX2, say DX or older, you stand a better chance. Even DX might be too clever to do it as simply as connecting a jumper. | ||
| + | |||
| + | ''All of the measurements you've suggested are helpful for getting a really good idea of what's going on with the chair. The temperature things can be spot-checked with a thermometer (infrared, or a taped on thermocouple), since it does not change so quickly that you can't stop playing and get the temperature checked. It's also fairly well understood (by me, at least) exactly what's going on with the temperature, and I tell you that further investigation won't give you much insight. | ||
| + | |||
| + | ''What you *should* look at more is voltage. Look at motor voltage, battery voltage, cable loss voltages, anywhere that voltage drops. You'll quickly see that shorter fatter cables and high quality batteries are the way to go. | ||
| + | |||
| + | ''Another crucial thing to understand, if you want to get so technical as to do current measurements and bring out oscilloscopes, is to get a good understanding of the difference between battery current and motor current. Once you understand that you can have 80 amps coming out of the batteries and 120 amps going to each motor simultaneously, you will see the importance of good motors with low resistance. | ||
| + | |||
| + | ''Once you get your power module reprogrammed for higher temperature, your wires thickened, good batteries installed, and the chair balanced for good traction, THEN (but maybe sooner) you are likely to start causing excessive motor heat that can degrade performance due to higher resistance, brush damage, and loss of magnet strength. If you can comfortably hold your hand on the motor, then the motor is nowhere near hot enough to be the limiting factor. I have seen motors get hot enough after all my mods to cause burns on your skin, if you were able to hold your hand in place for long.'' | ||
Latest revision as of 14:25, 30 May 2012
english version here http://wiki.electrolab.fr/Projets:Perso:2012:controler
Contents
Problématique
Il s'agit ici de trouver une solution au problème technique le plus important dans le foot fauteuil, la "chauffe", ou le fait que les fauteuils les plus sollicités ne peuvent pas tenir plus d'un match sans voir leur performances diminuer de façon importante.
L'hypothèse retenue pour l'instant pour expliquer la "chauffe" est la montée en température du contrôleur, qui met le fauteuil en sécurité et ralentit ses capacités : cela doit être vérifié.
Nous utilisons des moteurs de 400W avec des contrôleurs de 2X80A. L'électronique est de marque Néo Zélandaise, Dynamic controls, spécialiste de l'électronique de fauteuil roulant.
Contrôleur moteur
Audit du sous-ensemble
- 2 demi ponts à mosfets composé chacun de 8 transistors. - mesure de courant par sonde de courant "DC"
[complétez]
Analyse du comportement du contrôleur en situation
La première idée que nous avions eu est d'ausculter le comportement du fauteuil en situation réelle (lors d'un match) pour comprendre ce qui se passe.
Cela consiste à mesurer concomittament des grandeurs physiques telle que la tension batterie, le courant batterie et la température du contrôleur moteur.
Mesure de températures
Un thermocouple est à disposition mais la centrale d'acquisition qu'il est prévu d'utiliser accepte aussi les PT100 et les RTD. http://www.omega.com/prodinfo/rtd.html On peut aussi prendre un capteur silicium genre KTY81-121 avec R25 = 990 Ohms et qui varie de 700 Ohms entre 20 et 100°C Tmax = 150°C : un coup de tableur permet de convertir en température.
Mesure de courant
Shunt 200A dispo
Autres mesures
La centrale d'acquisition qu'il est prévu d'utiliser dispose de nombreux canaux (20 voies de mesure voire plus), il est possible de faire des mesures simultanées plus étendues que celles évoquées ci-avant. Par exemple, on peut faire plusieurs mesures de températures sur le contrôleur, sur les moteurs, tension équivalente des PWM, etc.
Acquisition en situation
L'alim de la centrale d'acquisition est "à transformateur" sur 230V : on peut mettre un petit onduleur 150VA pour faire le 230V sur le fauteuil : mais l'onduleur dispo fait du carré, donc pas simple.
Quatre orientations:
- soit ça passe avec le 230V carré (= voir si le transfo s'échauffe pas trop, sachant qu'un essai dure 10 minutes)
- soit on filtre le carré, mais faire un filtre 50Hz qui coupe assez raide vers 70Hz est une véritable gageuse
- soit on trouve un petit onduleur sinus
- soit, on se limite à 2 canaux (tension batterie, température contrôleur), et dans ce cas un scope portable sur batterie fera l'affaire.
Un oscillo ne mesurant que des tensions, il faut utiliser un convertisseur thermocouple -> tension/courant ou PT100 -> tension/courant [dispo] pour faciliter l'enregistrement des données de température. Exemple d'un utre convertisseur température-tension avec sa sonde : http://www.gsamart.com/webdata/prodimg/FLU_e0007903_lg.jpg
Possibilité de faire évoluer le contrôleur moteur
Quelques questions en suspens pour le moment :
- Est ce vraiment le contrôleur qui provoque la chauffe? (la réponse doit venir de l'audit en situation)
- nous avons des contrôleurs de 60A, est il possible de les passer "facilement" à 80A (économie importante à réaliser)?
Réponses de spécialistes de fauteuils roulants électriques
Ce projet a été posté (en anglais) sur un forum spécialisé sur les fauteuils roulants électriques, voici ci dessous deux de leurs réponses :
1
I also suggest that your friends download the DX System manual, and all other DX and DX2 manuals as well. They will, for example, already find that temp foldback (1) does respond to power module temperature, and (2) does reduce output. In other words, some of their questions are already answered. Moreover, they will discover that the foldback parameters are programmable and, by default, are pretty conservative. A slight increase in the temp for foldback could give a lot more playing time before foldback without actually risking the controller. Undoubtedly, JoeC will come along to tell you what he uses on his wife's soccer chair. He will also probably describe how he's used some small fans to improve heat dissipation. With the manuals, an OEM programming dongle and a PC you will at least know what temp has been programmed; even the cheapest commercial grade components have a temp limit of 80oC, and better components have temp limits quite a bit higher. So a foldback setting of say 60o is certainly giving you a huge safety margin. You probably should have some buffer as the temp sensor isn't necessarily at the hottest spot in the module, but a 20oC margin, assuming cheap components, is surely more than's needed to protect the module. Of course, you may find that avoiding PM foldback also leads to the motors getting rather hot - JoeC should again be able to bring the sound voice of experience to bear.
Lastly, there was some mention here that the difference between 60A and 90A PM's is just some on-board connections or passive components. I've never seen confirmation of this, though I suspect that it makes sense for Dynamic to use the same MOSFETs in all PM variants. If that's true, perhaps your friends can discover what needs to be changed.
Ciao, Lenny
2
To answer simply, here are replies to your questions:
1- Yes, it really is the temperature of the controller that causes the chair performance to be decreased. Keep the controller cool, and it will not reduce its output.
2- What to do? Reprogram it to a higher value, and it will be able to work harder. I have reprogrammed these controllers to a maximum temperature of 85C, from the stock value of (I think) 60C. I have used fans blowing on the controllers, and this helps. I have mounted the controller on a flat aluminum plate, and this helped a little, but not as much as fans, reprogramming, and moving the controller to a space where it can get free air flow.
3- Can you convert 60A DX2 to 90A? Probably not. As the design sophistication and manufacturing control is improved, they are less likely to overbuild the controllers, and more likely to have diagnostic self checking at power-on that will detect and object to any tweaks. If they are older than DX2, say DX or older, you stand a better chance. Even DX might be too clever to do it as simply as connecting a jumper.
All of the measurements you've suggested are helpful for getting a really good idea of what's going on with the chair. The temperature things can be spot-checked with a thermometer (infrared, or a taped on thermocouple), since it does not change so quickly that you can't stop playing and get the temperature checked. It's also fairly well understood (by me, at least) exactly what's going on with the temperature, and I tell you that further investigation won't give you much insight.
What you *should* look at more is voltage. Look at motor voltage, battery voltage, cable loss voltages, anywhere that voltage drops. You'll quickly see that shorter fatter cables and high quality batteries are the way to go.
Another crucial thing to understand, if you want to get so technical as to do current measurements and bring out oscilloscopes, is to get a good understanding of the difference between battery current and motor current. Once you understand that you can have 80 amps coming out of the batteries and 120 amps going to each motor simultaneously, you will see the importance of good motors with low resistance.
Once you get your power module reprogrammed for higher temperature, your wires thickened, good batteries installed, and the chair balanced for good traction, THEN (but maybe sooner) you are likely to start causing excessive motor heat that can degrade performance due to higher resistance, brush damage, and loss of magnet strength. If you can comfortably hold your hand on the motor, then the motor is nowhere near hot enough to be the limiting factor. I have seen motors get hot enough after all my mods to cause burns on your skin, if you were able to hold your hand in place for long.
