A Disturbance Observer-Based Integral Sliding Mode Control for Two-Level Power Converter

Direct current control is an attractive alternative to control the power converter. To design a control strategy for tracking reference current, the algorithm can be designed in both the dq synchronous reference frame or the alpha beta stationary reference frame. While the PLL is required to transfer the current variables into synchronous reference frame, this process may result in slow dynamic responses of the system. This paper resolves this issue by proposing a disturbance observer-based integral sliding mode control (DO-ISMC) strategy for three-phase two-level power converter in the stationary alpha beta frame. By introducing an integral term in the sliding mode control, the proposed current controller can achieve high performance in steady state and transient. Moreover a linear disturbance observer (DO) is integrated into the control scheme estimating the lumped disturbances to speed up system convergence rate and improve disturbances rejection ability of the system. Finally, the simulation results are provided to verify the feasibility of the proposed approach and show the its superiority compared with the proportional plus resonant (PR) controller.