I'm working on designing a controller for a grid tied inverter.
I'm not able to find a suitable reference or book that might help in this case.
What I have understood now is:
- There must 2 loops (inner current and outer voltage loop) for better control
- I have a basic understanding of modelling of inverter with LC filter using state space analysis.
- Basic compensators except proportional resonant controller require DC for tracking. So direct-quadrature axes transformation is necessary. I understand the mathematics behind it.
I don't understand whether to use PI controller and tune it or manually design a controller using control theory.
I don't understand why there must be two loops and how to design the voltage compensator transfer function such that it gives current reference using voltage error.
Please help me with references or an explanation as I couldn't find any book that explains this in a mathematical manner.
This is similar to what Im trying to achieve. Where the ig and Vdc that is being given as a feedback to calculate error are direct-quadrature axis transformed.