Hi,
As per my understanding, you are plotting the output voltages and current of a SEPIC converter when it operates independently and when it is connected to a grid-tied inverter. In the second case, the current and voltage plot shows ripples at the start and then their values get saturated.
I used a standalone SEPIC converter found at the MathWorks File Exchange forum to reproduce the graphs. I was able to reproduce the ripple free current and volage graphs.
To reduce the voltage and current plots of the SEPIC converter with a grid-ties inverter, try out the following steps:
- Increase the capacitance at the input and output of the SEPIC converter as it acts as a low-pass filter which helps smoothening voltage ripples.
- Adding more inductors in series at the input of the SEPIC converter help in filtering out current ripples.
- Operating the converter at a higher “switching frequency” may reduce the ripples amplitude.
Refer to the following MathWorks documentation links below for more information on modelling a “Grid-Tied Inverter” and the SEPIC converter:
- https://www.mathworks.com/discovery/grid-tied-inverter.html
- https://www.mathworks.com/matlabcentral/fileexchange/91670-sepic-converter
Hope this helps in reducing the ripples!
