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Recent content by Highspeed

  1. Highspeed

    DC brush sensorless control

    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?
  2. Highspeed

    Baloon question

    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...
  3. Highspeed

    4-20 mA loop sheilding

    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
  4. Highspeed

    Baloon question

    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...
  5. Highspeed

    Sine filter for PWM inverter output

    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...
  6. Highspeed

    Electromagnet core material suppliers

    I have worked with those guys . 100% reactive and efficient http://www.protolam.com Good Luck HS
  7. Highspeed

    FFT Interpretation

    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...
  8. Highspeed

    FFT Interpretation

    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...
  9. Highspeed

    100 kRPM Brushless Motor Design

    jb, any reference or drawing of a notch filter that is efficient for EMI for the kind of load we are talking about? I'd like to test that HS
  10. Highspeed

    Teaching Motor Controls.

    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...
  11. Highspeed

    100 kRPM Brushless Motor Design

    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...
  12. Highspeed

    Rotor/stator capacitance in induction motors

    Another usefull link on that topic: http://www.ab.com/drives/techpapers/ieee/ieee.html Good luck HS
  13. Highspeed

    Take off 6dB (or more) from a noisy source

    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...
  14. Highspeed

    100 kRPM Brushless Motor Design

    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...
  15. Highspeed

    100 kRPM Brushless Motor Design

    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...
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