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Recent content by iop995

  1. iop995

    ADC FORMULA

    Mystery number is convertion range = range 1 / range 2 = (288-238) / (50-30) = 50/20=2.5
  2. iop995

    Torque limitation in Field Oriented Control of PMSM

    I think system is not completely decoupled at small - zero speed because various errors; most probably in current sampling/conversion (not correct effective values), and / or high error in angle position at zero speed. Maybe at/near zero speed is better an angle estimator (switch to sensorless).
  3. iop995

    Hack cheap synchronous motor for single direction?

    This is so-called hysteresis motor. Rotor is made by high hysteresis material and in small time from start-up catch and remain synchronous with one rotating field. www.faculty.umassd.edu/xtras/catls/resources/binarydoc/3636.ppt
  4. iop995

    Super Cap leakage current

    I think main problem is that battery are avoided in that application (maybe customer request and/or new EU rules about RoHS) or need a lot of tests/aprovals that increase cost. So, need to find a solutions w/o battery. At so small current I think it's ok with caps or ultra-caps.
  5. iop995

    Super Cap leakage current

    For such low current, think at this schema: if voltage for RAM/clock memory is 5V, you need about 2.5microW power; to avoid battery or ultracap, nay use remaining filter capacitors energy at power failure. Add a step down circuit (cheapest a resistor w/ zenner) or trafo dc converter if you need...
  6. iop995

    Super Cap leakage current

    Supercap main advantage over battery is fast charge / release energy cycle. If your application is for memory cache RAID controller or similar, supercap is ok but must be used to provide power to RAID card for few (mili)seconds, enough to move data from volatile cache memory to a non-volatile...
  7. iop995

    240VAC single phase to 650VDC voltage doubler / boost converter.

    80kW, wide range input and output voltage / 28kg water cooled. http://www.brusa.eu/en/products/converter/power-dcdc-750-v/gic246.html Don't ask price :) Best solution is DC/DC boost converter. I'm sure there are many other much cheaper solution than that (ok, not so small weight).
  8. iop995

    Which motor to choose?

    Gearbox steper in open loop. Cheap and sure. I think you don't need continously moving, steps of 0.1 degree being enough, step motor is one more best solution. Sure, step pulses are send accordingly solar tracker sensing.
  9. iop995

    Relay EMI is triggering sensors on custom Arduino PCB

    I think problem come from initial high di/dt, not from contact arcing. From photo, PB1 and PB2 are far away form Arduino connector with very long traces that go too close to relay. For PB3 (reset) it's not same situation - it's close to Arduino connector - and don't "see" same EMI in traces. I...
  10. iop995

    DC/DC converter giving acoustical noise

    Try to cover coil (or coil + capacitor even) by a piece of copper or aluminum. Buzzer is too close to switching converter. Maybe more easy, as sugested, is to move buzzer away by twisted wires of minim 10cm.
  11. iop995

    480V 3 phase moter with VFD

    More than 20-25 battery in a string is not recommanded and equalization circuit increase cost. I think you may use 20 battery (240V) and a buck/boost DC-DC converter to 480Vdc connected to VFD DC bus. Same converter, configured in buck topology may be used as battery charger, feed from VFD bus...
  12. iop995

    overloaded pump

    If changing to a bigger motor is difficult, maybe it's easier to add cooling to existing one. With 20% current overload need to remove about 40% more heat; try external cooler with eventualy, if not too hard and/or too expensive, some water pipes between cooler flow and motor. Move overload...
  13. iop995

    PMSM control strategy

    @Mike Electric car is a system that need a driver, it's not autonomus. Driver impose a speed (desired/reference) and driver also sense car speed and adjust pedal to reach desired speed. That is big loop and don't treat it as a standard velocity loop. No need to tune this loop, it's indirectly...
  14. iop995

    PMSM control strategy

    Big loop is car speed loop. Inside it there are various loops that contoll/look-up for currents (motor / battery / brake - charging, etc.), anti-slip, torque-limit, inverter control, etc. depending of complexity / requirments of project. As motor choosed change, one or more of such internal...
  15. iop995

    PMSM control strategy

    PMSM controll strategy (algorithm) is one issue, which may be made by various controllers like jaref said and control of EV speed is another issue, is the big loop closed by driver. Optimal control for PMSM may be FOC but is expensive and not indeed needed in EV applications (in EV must limit...
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