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    AC motor driving logic with panel

    I want to run a 2HP AC (3 phase) 440V squirrel cage induction motor from Solar panel (600V, 100Watts panel) through a motor drive.
    I am using 3 Phase IGBT bridge to produce 3 phase output. For starting we are using V/F control. But as ambient light reduces Imp reduces since the load is constant it makes the input voltage to fall drastically and whole system coming to stop.

    •   Alt20th January 2017, 13:38

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    Re: AC motor driving logic with panel

    Did you consider that rated motor power is 1.5 kW?


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    Re: AC motor driving logic with panel

    Unless you are using a premium efficiency motor.....The no-load losses at rated speed for that motor would easily be in the 400 to 600 watt range.
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    Re: AC motor driving logic with panel

    Yes motor is1.5KW.
    My doubt is as the when panel power output reduces(when light conditions change) is it possible to run the motor at reduced power??



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    Re: AC motor driving logic with panel

    Hi,

    is it possible to run the motor at reduced power??
    Theoretically yes. But how does your IGBT control system achieve this?

    Klaus



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    Re: AC motor driving logic with panel

    By reducing adjusting duty cycle and freqency ?? I am not that familiar with drives



    •   Alt21st January 2017, 09:59

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    Re: AC motor driving logic with panel

    An industry standard VFD allows to adjust the motor voltage independent of the frequency, in so far you can reduce the motor power. Because friction losses of an induction motor are pretty low, it's possible to run the motor at reduced power. But that's only possible if the load torque is respectively low. Is it so?



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    Re: AC motor driving logic with panel

    load can be lowered.
    Let me make clear one scenario.
    I have done one DC motor drive (BUCK) with solar panel input. In that if the panel power is not sufficient to run motor at full power we will run the motor in lower speed by reducing duty cycle of IGBT switching then output voltage decreases respectively output and input current reduces thus tracking the MPP of panel. Like wise is there any method in AC motor drive??



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    Re: AC motor driving logic with panel

    Hi,

    --> reducing frequency as well as voltage.

    Klaus



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    Re: AC motor driving logic with panel

    It is going to use for agricultural purpose. So if less input>>less output More input>>more output.

    - - - Updated - - -

    there are lot of control methods out there Vector control,v/f,... so which one i have to use??



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    Re: AC motor driving logic with panel

    In case of doubt V/f as already suggested.

    It is going to use for agricultural purpose
    You still didn't tell anything about the load characteristic. If the load involves e.g. a large breakaway torque, other control methods may be necessary.



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    Re: AC motor driving logic with panel

    Load is compressor based borewell pump used for water pumping.



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    Re: AC motor driving logic with panel

    Borewell pump is regularly a centrifugal pump with small starting torque. But it has zero output unless the speed is sufficient for the discharge head. A storage battery would allow at least intermittent pump operation in this situation.


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    •   Alt21st January 2017, 12:51

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    Re: AC motor driving logic with panel

    I researched well pumps when I put together my backup power system (in 1999). The type which is best suited for a PV installation is positive displacement, DC powered. I purchased one rated 24VDC at 2A. In my tests it ran satisfactorily (although slower) at lesser voltage and Amperes. Specs state it can pull water up from max depth 230 feet. The brand was Solarjack.

    Our house had a spinning vanes type which works on AC house voltage and draws a lot of current. In the event of longterm blackout I intended to pull the power-wasting pump out of the well, and lower the DC pump.


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