I'm modeling three phase Inverter using three-single phase full bridge inverters. My aim is to provide constant voltage at both unbalanced and non linear load conditions. Output is delta connected and there is no transformer. Since I have three independent single phase inverters, I thought it would work well. I have V loop, followed by current loop where just current limit is implemented. I modeled in simulink and the results are poor factor and three phase line currents are not displaced by 120 deg. Please help
Try to change the PWM method it might help you out. the output of any inverter depends on how good is the switching methods you are using.
Dear Jaikumar M,
I sugget to analyse the current waveform frequencies first.
Try to use PR controller instead of PI. Probably the unbalance introduces a negative sequence voltage that falls beyond the PI capability.
Dear Jai Kumar,
I support the answers given above, you have to analyse the output voltage using FFT, so that you can find the frequency component in the output and also check the PWM scheme accordingly. If any help in simulation required, just mail me your model with the required document at [email protected].
In my thinking there may be problem of loading also.
Dear Jaikumar,
In your question you mention that your system corrects the voltage, but the current is out of phase. I assume you are referring to V and I from the inverter to the load, correct? In this case, the VxI phase shift depends on the load power factor.
You also mention that "...three phase line currents are not displaced by 120 deg.". Ok, but what about the the voltages? Are the voltages at 120 degrees from each other? If the volatge phase shift is Ok, than again the non-120-degree phase shift you see in the current might be a result of the imbalance on your load. How does your system behave with balance loads?
My point is: maybe your modelling is not wrong (it can always be improved, but it might be presenting correct results).
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