Model of 3750VA UPS on Simulink (MATLAB)

Discussion in 'Programmer's Corner' started by darkfeffy, Apr 1, 2009.

  1. darkfeffy

    Thread Starter Member

    Apr 1, 2009
    12
    2
    Hi,
    I need some help on my h-bridge inverter design. In MOST textbooks and pdfs I've been through the output filter (inductor+capacitor) is always connected. This means a relatively large current will be flowing in the capacitor even when the load is disconnected. Come to think of it! The inductor and capacitor are in series. This should decrease the overall efficiency of the device. Is this normal? How can this be prevented?

    I ask this because I am simulating a 3750VA UPS on Simulink (matlab). I am using a buck stage (converts 311VDC to 48VDC to charge battery) and booster stage just before the inverter (converts 48VDC to 360VDC).

    When the load is disconnected from the inverter, I get an output voltage of 360Vdc and current of about 50A (with spikes) at the output of the booster. I thought this is abnormal as I expected to see almost zero current. Now, during full load, the current goes up to about 100A (spiky as well) instead of the expected 12A for a 3750VA load(90% efficient).

    Could the simulation results be faulty or is this normal?
    Thanks alot
    Ed
     
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