DC motor load for boost converter

Discussion in 'General Electronics Chat' started by Melving, Apr 1, 2015.

  1. Melving

    Thread Starter New Member

    Apr 1, 2015
    2
    0
    Hello my project involves making a boost converter that can supply a constant 48V when the input is changed from 12V to 24V. The duty cycle supplied will be changed using a feedback loop. A DC motor load will be connected to the output but I have no idea how to simulate it or what effect the DC motor load will have on the boost converter. I have tried to simulate it on PSCAD using an inductor and series resistor but up until 10^-3 H (value of load inductor) the output waveform shows no change. Only values greater than 10^-3 H show a significant change in the output waveform were the settling time increases. Need tips regarding the effect of the DC motor load.
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,292
    1,255
    A schematic might be best. Or you can just use a resistor as a load to get it working.
     
  3. Melving

    Thread Starter New Member

    Apr 1, 2015
    2
    0
    I
    I have already done the simulation with a purely resistive load and it works perfectly, it's just that I'm unsure what the motor will do to the boost converter or the feedback loop when connected as my prototype will be tested with a DC motor of 240w rating.
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,292
    1,255
    A schematic would still be best, but try it with 1 mh in series with 10 ohms. It may take some time for the current to build up but the voltage (assuming it is volte feedback) should come up.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    The problem of a DC motor supplied by a boost converter is what happens during startup. The usual behavior is that the converter drops to it's knees and doesn't bother to stop there, since the startup current demand is many times the running current demand. The next problem is what happens at shutdown, since most converters are happiest when there is at least some load. What you need is a converter with no minimum load requirement and a stiff response to load transients. I would start with a design spec that provided for at least three times the motors running current. This is going to require an extremely heavy current draw from the low voltage (12V) source.

    How much current does the motor require in the steady state?

    What happens in simulation if you try to drive a 10 milliohm resistor (large current demand)
     
    Last edited: Apr 1, 2015
Loading...