Usually , it's easier to have a position feed back of a DC brush motor by monitoring Back emf rather than current
What do you want to control, speed, position?
This is an 5 month old topic and things have moved
Now we are molding this Item and will receive the first lot within days.
We are not really stuck with silicon but the device is medical and has to comply with cytotoxicity testing as per IEC 10993-x. with the current setting using the silicon...
Have you tried double shields...
In a similar situation (not as long though), Inner shield was connected as follow :
Signal >>> Instrumentation Amplifier >>>> DAQ
>>>> Inverting AMP >>> Shield
opened at the other end
Top layer shield was earthed both ends.
HS
In our application, we are using something that looks like a baloon with two inputs, the volume is ~100 mL
currently this item is made using a silicon dispersion and a ptfe Master is put in this bath 15 times with pauses to get the correct 0.2mm thickness The whole process takes less than a...
As far as I know there aren't any special rules for Sine filters for Motors
Basically the filter topology will be derived from
1-how far you pwm f is from the frequency to achieve
2-If your Pwm'ed signal is Sinus or not
3-If you are running at constant speed or variable speed
4-What distorsion...
Add on..
Rethinking to your setup and assuming the following:
Your Opto TTL triggers perfectly at the edge of your blades that are perfectly spaced.
Then your vibration (changes in speed)information is contained in the timing between edges of your TTL signal
Assuming 60 Hz / 14 blades gives 840...
Hi,
In my opinion, if you are willing to look Torsional rotor vibrations and used an optical tacho on the blades for that, the usefull signal will be among the noise.
Basically with this setup, you have 14 valid samples per turns and by derivating them, you'll get 14 speed informations per turn...
Years ago, I have been through that and I will extend what PUMPDESIGNER was saying .
The very first step I used was to try to make the students love electromagnetism (funny levitation things, magnets in aluminium tubes ....)and know how to use handbooks .
I did not spend a full semester dealing...
100kRPM=1.66kHz,
A clean sine wave needs at least 32 steps driving to PWM minimum time = 1/53kHz = 18.75µs this will also allow a reduced size filter to avoid bearings currents
based on a 8 bits resolution, smallest PWM element = 73ns
it will be tough to get that with "soft" switching...
I finally got the design to work over expectations
You cannot tell when it is on.
I did find a really great enclosure damper somewhat "magic" as opposed to what I tested before and wanted to let you know:
Manufatured by TMAT it's named P15/D05.
Very usefull for plastic enclosure...
Still based on our 100W design:
Keeping bearings far away in high induction high speed motor not to put them in the flux path (1/100th of the flux through magnets is still a lot).
Now what is far away: an initial prototype with 1.5 mm airgap toroidal stator, we had bearings 10mm away
Eddy...
We have a running design up to 90kRpm but not at that power requirement, only a hundred watts.
Tips :
>> Slotless/toothless "large airgap" stator (toroidal)
>> keep magnetization around 1.8 Tesla using N40H 2 poles ring magnets
>> Sensorless operation (ST72141) using back-emf or...
Yes, re-reading me.. wasn't that clear!
I am a newbie in this area.
What I'd like to understand is in fact what is the rational approach when designing vibrations dampers using elastomers given constraints such as thickness Shore, expected absorbtion coefficient....
The Visco part as far as I...
Hi all,
When dealing with rubbers, silicons and others, it's rather easy to find data's around shore and all the "elastic" properties of a given material.
The viscoelasticity of those materials is something I am interrested in to evaluate efficiency of vibration dampers and I did not...
I am looking for a very small peristatic (Peristaltic)head to do the following job:
In 8 hours, at ambient T°, 200 to 400 ml of water has to go from one reservoir tank to a chamber where this water will evaporate.
The approximate (huge [smile]) height the water has to climb is 5 cm
A close loop...
Finally got it to work, and I have 2 options under deeper testing.
Keeping the original setting and gluing 1/2 bearing with Loctite 603
Gluing the 2 bearings with the deadweight while curing
Both are running so far according to expectation.
I think I'll keep solution 1 as I have to guarantee...
If you use Labview, You can use it, but you need to develop your tool and that is time consuming (In Labview you have the vi's to run the sound card).In our lab that is our approach (16 bit DAC for free with the sound card)
CoolEdit was a software that used to have a limited trial version that...
