Maximum erpm for sensorless controllers? Crystallyte Lyen?

[phebbler]

I have been scouring the forum looking for a solution to my problem. I have a 6 pole motor that I want to run sensorless and I need 5000rpm (30000 erpm) out of it.

I want to purchase a finished controller and it needs to be high voltage 72-100V the amperage would need to be between 40 and 60 amps. I

Does anyone know of a high voltage controller available that do this? I know most hub motors have a lot more than 6 poles so 5000 rpm on a 6 pole motor is more like 1305 on a 23 pole motor. Any help would be appreciated.

 

[Thud]

welcome,

Here is some info straight from the source,
http://endless-sphere.com/forums/viewtopic.php?f=28&t=22333

there is intertwining info regarding 7 pole pr motors & the astro flight motors (4 pole prs?)

hope that helps. Good Luck

 

[phebbler]

Thanks for the link. This post is what actually prompted my question. I have been in contact with both Lyen and Kenny at Crystalyte and both say that sensorless controllers are only used for low speeds or if you have damaged hall sensors.

Kenny emailed saying that their 72V 40A sensorless controller is only good for 300-500 rpm.

Lyen replied to a PM saying: "For the sensorless controller, the maximum suggested speed I can tell you on a typical 9C 2807 is 20mph regards, of battery voltage. 38mph on a Crystalte HS3540.”

Considering the HS3540 has 23 magnetic pole pairs (according to another posting here) then Lyen’s 72V sensorless controller has been tested under load at about 463 rpm or 10649 Erpm using the HS3540 (within the range that Kenny replied).

Kelly sells KSL sensorless controllers up to 120V nominal at 125 amps cont. but the specs states that 17000 erpm is the maximum (739 rpm on a 23 pole motor so we compare apples to apples)

However where my confusion comes in is in the post you linked to, Lyen has videos showing the Astro Flight 4 pole motor turning over 7000 rpm or 28000 Erpm unloaded. I know that under a load the RPM will drop quite a bit, but it seems like he proved that his controller has no problem commutating at over 28000 Erpm.

R/C controllers can commutate at extremely high rpm but lack the increased voltage I need for my project (72-100V). I did some testing with a CC Phoenix ICE HV160 but it is limited to 50V and I pushed the envelope to 60V getting about 3738 mechanical RPM with no damage but according to my calculations I need above 80V to achieve the loaded rpm I need (5000 mechanical RPM) and I could not afford to destroy a $280 controller. My motor has 6 pole pairs so I was able to get the motor to turn 22428 erpm with no problem using the hobby controller.

All this evidence suggests that the speed of sensored commutation is not the factor that would limit these controllers to below 17000 Erpm. I would just purchase one and try it but if anyone has experience proving the ability for high rpm sensorless operation it would put my mind at ease. I just am hesitant to purchase a controller when the builders say that high rpm is not possible but I need a solution because adding hall sensors for my application is not possible.

Thanks again for any information