PV inverter control in simulink based on backstepping control

I am trying to implement Backstepping control in simulink from this paper "Nonlinear controller Design for Single-Phase Grid-Connected Photovoltaic Systems".Everything seems fine but DC-Link capacitor voltage is always increasing with a slow pace.it never settles at 400 but keeps on increasing slowly. any idea ?

[Adrián Casado]

400 is the voltage at Maximum Power Point?

Answer 1

[asitha samarasekara]

I simulated grid tie inverter using matlab.i could get controlled output.but inverter input current vary as in following wave form.do have any idea on this

[Shah Fahad]

Hello asitha,

I believe you have plotted current of the dc-link capacitor. Since it has a continuous on/off charging/discharging due to inverter as well as dc-dc converter switching, therefore, the current is going towards discontinuity. I presume, you have regulated the voltage at dc-link. If the voltage is regulated, then the current is not going to be a problem for normal loads. However, you can improve it by using proper equations and increasing the capacitance of the dc-link or controller itself. Depends on your research direction.

Good luck.

[asitha samarasekara]

Shah Fahad Thank you very much for you comment. I'm developing a single stage single phase grid tie inveter. for that It need to measure the input current of inveter.but as this figure it goes to negetive some times.

[Shah Fahad]

Dear Asitha,

It is extremely difficult to solve your query without having a look at your controller and circuit.