Comparison between two controllers for a modular three level boost converter in renewable energy systems; indirect sliding mode and PI

Fuel cells and photovoltaic systems have many applications among renewable energy systems. DC converters play an important role in these systems. According to characteristics of renewable systems and nonlinear behaviour of the DC converters, control of them is essential. In this paper, the control of a DC modular converter is investigated. This converter is based on a three-level boost converter. This topology can increase the output voltage level compared to the input voltage level and balance the DC output voltage. There are two capacitors in each module of the converter and a capacitor is shared between two modules. The performance of the indirect sliding mode controller is compared with a classic PI controller. The system is simulated using MATLAB/ Simulink software. The simulation results are presented in several scenarios. The dynamics of the input powers and the voltage balance are studied. These tests are performed under changes in the input power, the resistance load and the input voltage. It is obvious that the proposed controller has good performance during operating point changes. The superiority of the proposed controller over the classic controller is shown for all tests. In transient mode, the linear controller is unable to balance capacitor voltages by changing the input power, input voltage and load.