dangerzone said:Arlo1 said:I have an order in for a sevcon G8055. I will run collossus with a sevcon and eventualy rewind it for max effieciency.
With the second collossus I am still going to rewind as a 9 phase so I need one more 24 fet bord and one more 36 fet bord to build my 3 bord 9 phase controller!
So if anyone has a 24 fet kit or 36 fet kit or pcb please let me know.
Thanks.
I layed up 4 of 5 peices of Carbon fiber bodywork last night for the YSR and should have it finnished by the end of the month. I am in ottowa till the 17th so I hope to have a pacage or two to pick up when I return home so I can finish my Kickass E-ysr build!
What is the max rpm of the G8055..?
Programing things with a computer is my favorite part.Biff said:I have been using a Sevcon Gen4 recently (not for this motor, but another low inductance / resistance motor). I can say that the Sevcon does not like to operate over 660Hz, it does not like low inductance that much either but it doesn't blow up. It might work up to 800Hz, but you will probably need help from a sevcon technician to get the control parameters right, and the control at those speeds will be rather rough (think pulses of plus or minus 100 Amps from the desired current). This will definatly take some time to configure on a Sevcon, you will not be able to just hook it up and make it work, you will need to program it very carefully. I might be able to help getting the sevcon working with this motor, and then share the Device Configuration File or parameters for those of you who are interested.
-ryan
Nuts&Volts said:Biff I would definitely be interested in that solution down the road when these motors are available
What exactly is limited to 660HZ? is that the switching of the phases? So the motor could be run at 6600RPM (660Hz*10polepairs)
Thanks
Kyle
At the higher rpm the short PWM is not as crutial so is it possible to step it down to less pwm??????? I want my motor to spin 7000-8000 rpm!Biff said:Nuts&Volts said:Biff I would definitely be interested in that solution down the road when these motors are available
What exactly is limited to 660HZ? is that the switching of the phases? So the motor could be run at 6600RPM (660Hz*10polepairs)
Thanks
Kyle
660Hz is electrical frequency of the phases. RPM = Freq * 60 / poleparis.
for a 20 magnet motor (10 pole pairs) that would be
660* 60 / 10 = about 4000 RPM
above that your running gets rough because there are not enough PWM pules per cycle.
-ryan
If I ever get one in my hands I will let you know. :wink: Meen while I will keep pushing forward and rewind one motor as a 9 phase, or 3 seprate 3 phase motors to be more acurate.SplinterOz said:Ok so this is not good news.... My motor has already spun up past 6,000 no load and I expect over 5,000rpm under load. Now that is with a 72volt pack. The prototype is mechanically limited by the skirt bearing to about 8,000, however the prod model should do 14,000rpm (if you give it the volts.)
Now I am really wondering if this is the right controller?
Arlo1 said:Hey Ryan
I can't help but wonder what the chances of using a step up or down transformer hooked to each phase???? Give the fets a Higher amount of inductance to work with. For instance have a set of 10x step down transformers for starting out so the controler would have 10x the resistance then once you are up to speed a bit have some relays switch off the transormers and run the phases from the controller right to the motor!
Simply put you dont gain performance with wye delta you just take stress off your controler!crap said:How about just wrapping the motor cables around some ferrite cores? It will add inductance in series and help the controller but doesn't need to add much losses. It is sometimes done with ironless motors for the same reason. Also, a y/d switch would be nice, but mainly for performance reasons. Can all six end windings be easily accessed and extended to the outside of the motor?
No for the same given amps and volts WYE and DELTA produce the same torque!crap said:Unless the controller is so powerful it can push the motor torque to the limit in delta termination, being able to switch to y termination at low speeds will enable an increase in torque. Switching back to delta at higher rpm's will restore the rpm capability. A y/d switch should act about the same as a gearbox, unless (like i said) the controller is already powerful enough to push the motor to it's very limits. Seems like something with potential to increase performance...
Nope it is 100% correct!nieles said:sorry to say it arlo1 but i think your statment is not true.. KT (torque constant) is inversely proportional to KV. the delta/wye difference is sqrt3 (1.73).
the output watts for both motors would be the same (if the efficiency is the same)
but the delta motor has 1,73 times more rpm than the wye motor
the wye motar has 1,73 times more torque than the delta motor