3-ph inverter with dq control. Model issues (Current waveform)

Hi Everyone, First ever post so hope theres enough info.

I have created a simulink model based on a youtube tutorial for a 3 phase grid connected inverter with dq Control. The model runs fine apart from the current waveform doesn't look right, I expect to see a near perfect sinbusoidal waveform in phase with the voltage waveform (yellow). I cannot find my error and wondered if anytone could have a look at my model?

Thanks

Answer 1

[Sayan]

Hi Michael,

It seems the control logic is right. If the current waveforms are not matching as expected, the probable reasons for the issue and their fixes are mentioned below.

• The PI controllers may not be properly tuned. Try to tune the controller 'Kp' and 'Ki' values to change the reference voltages of the 3 phases. Currently, the reference voltages (Vref) are fluctuating between -1500 and +1500.
• Ensure the inductance and capacitance values of the L-C-L filter are properly chosen to reduce the harmonics.
• Verify that the proper solver is chosen to solve the circuit. If accuracy is not the goal, try using stiff solvers like ode15s, ode23t, etc.

You can try the following example too. Similar to your model, a 3-phase grid-feeding inverter has been designed here.

https://www.mathworks.com/matlabcentral/fileexchange/72702-grid-connected-three-phase-inverter-control-using-dq-frame

Hope this helps finding your desired result.