Integral sliding-mode-based current-control strategy for single-phase current-source inverters

This paper proposes two current-control strategies adopting the sliding-mode concept for single-phase current-source inverters (CSI) feeding a resistive load. The first strategy is based on forming a general sliding surface using the error variables of the inductor current and capacitor voltage. However, it is observed that with this type of control there exists a steady-state error in the capacitor voltage. Therefore, an integral sliding-mode-based current control using an additional integral term of the error variables in the sliding surface is proposed. It is observed that the additional integral term alleviates the steady-state error in the capacitor voltage. The existence conditions for stability are determined for both control strategies. It is shown that the compliance of the existence conditions for full operating range of the CSI can be assured if the complete ranges of operating conditions are taken into consideration. In order to reduce the switching losses and improve the quality of the output voltage, the three-level hysteresis function is implemented as two separate two-level functions for the switching devices. Computer simulations are performed to verify the theoretical results and for comparison with existing methods. Experimental results are also presented to support the theoretical considerations.