+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Newbie level 1
    Points: 15, Level: 1

    Join Date
    Jan 2020
    Posts
    1
    Helped
    0 / 0
    Points
    15
    Level
    1

    DC Booster for Solar Pump

    I would like to design a dc booster for a solar system. System consists of 6x 265Wp panels in series, which equals roughly 1600Watts, 200V, 9 Amps.
    I need to boost the voltage up to 350V to feed into a VFD which in turn drives a 0.75kW motor.
    Is this possible? Where should I start?

    Thanks

    •   AltAdvertisement

        
       

  2. #2
    Advanced Member level 5
    Points: 24,859, Level: 38
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,762
    Helped
    1055 / 1055
    Points
    24,859
    Level
    38

    Re: DC Booster for Solar Pump

    Of course this is “possible”; ANYTHING is possible. But this is not trivial. Basically, you need to chop your 200 VDC into pulsed DC, and step it up using a diode and inductor, while not electrocuting yourself or burning down your house. Do a search for “boost converter”.



    •   AltAdvertisement

        
       

  3. #3
    Advanced Member level 5
    Points: 12,984, Level: 27

    Join Date
    Aug 2015
    Location
    Melbourne
    Posts
    2,133
    Helped
    776 / 776
    Points
    12,984
    Level
    27

    Re: DC Booster for Solar Pump

    look up "boost converters" used a lot in transformerless grid tied inverters to step up the PV panels to 380VDc for inversion to 230Vac ...



    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 53,787, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    13,110
    Helped
    2617 / 2617
    Points
    53,787
    Level
    56

    Re: DC Booster for Solar Pump

    A voltage doubler can provide your step-up ratio, almost 2x.
    Two voltage doublers acting symmetrically provide AC to the load.

    Simulation using Nakagome type.

    Click image for larger version. 

Name:	Nakagome 2 caps 2 dio 8 transis 200VDC 100 ohm load gets 370VAC sq-wa.png 
Views:	4 
Size:	50.9 KB 
ID:	157296

    Bias was adjusted to transistors so that current draw stays under 9A.

    To obtain sinewave output, add PWM and/or filtering.

    - - - Updated - - -

    Clock frequency can be anything you wish. There's a chance your motor draws greater current at lower rpm, resulting in higher temperatures.



  5. #5
    Member level 4
    Points: 872, Level: 6

    Join Date
    Jun 2017
    Location
    near the sea
    Posts
    68
    Helped
    14 / 14
    Points
    872
    Level
    6

    Re: DC Booster for Solar Pump

    Quote Originally Posted by jatrom View Post
    I would like to design a dc booster for a solar system. System consists of 6x 265Wp panels in series, which equals roughly 1600Watts, 200V, 9 Amps.
    I need to boost the voltage up to 350V to feed into a VFD which in turn drives a 0.75kW motor.
    Is this possible? Where should I start?

    Thanks
    I see several problems you need to address
    1/ What is the starting inrush of the motor & pump and where do you expect it to be supplied from ?
    2/ You seem to assume your panels will be at 100% insolation all the time, is this true, do you live in a desert with no clouds and the sun directly overhead ?
    3/ You make no mention of maintaining the panels at there maximum power point, if you don't your power will collapse

    IMOP you have chosen a very complicated project for an absolute beginner with little or no knowledge of PV etc
    Try addressing the above issues or publishing the answers here and someone might be able to help you a little more :)



    •   AltAdvertisement

        
       

  6. #6
    Advanced Member level 5
    Points: 12,984, Level: 27

    Join Date
    Aug 2015
    Location
    Melbourne
    Posts
    2,133
    Helped
    776 / 776
    Points
    12,984
    Level
    27

    Re: DC Booster for Solar Pump

    agreed - you need a peak power ckt to draw the max from the panels ( even on on a sunny day ) and batteries to store (hopefully) the excess so that the load can run at other times, i.e. early morning & sunset --

    else the load can only run when there is sufficient sunshine - fine in the desert on the equator - but not so fine for places with cloud cover etc ...



--[[ ]]--