Growing demand on sustainable energy systems such as photovoltaic (PV), fuel cell or battery based energy systems has made the efficient conversion of electric power a primary requirement. In this regard, a single-phase multi-source switched capacitor based boost multilevel inverter (SCBMLI) is proposed. The working principle, design criterions and operations of the proposed topology will be discussed.
In multi-source systems, it is imperative to control the current extracted from each source. Moreover, in SCBMLIs, the capacitor charging time is a crucial parameter as it affects the gain and capacitor charging current. Considering this, a varying carrier shift based pulse width modulation (PWM) is proposed for multisource fed SCBMLI to control the source currents without affecting its performance.
A loss modulated deadbeat current control (DCC) is proposed for a grid connected inverter system. This control calculates the required modulation signal by considering the losses occurring in the system at every switching cycle. The proposed method tracks the reference current with negligible error. The loss component used in the control method eliminates the effect of sensing and computational time delay and reduces the sensitivity to parameter mismatches. The proposed DCC is extended for deadbeat based direct power control (DDPC) without an inner current control loop. Further, a modified DDPC is presented to eliminate the delay of one switching cycle which is inherently present for the grid current in DCC. The proposed control methods are realized on proposed multi-source fed SCBMLI. The steady-state and transient behavior of the control methods are verified in simulation and experimental studies for a power rating of 500 W under various system conditions. The proposed algorithms are able to track the reference signals with fast transient response and negligible steady-state error. The deadbeat control and varying carrier shift PWM is combined and applied to multisource fed SCBMLI with one DC and one PV source.