Backstepping based Nonlinear Control for the Modular Multilevel Converter to Against Parameters Variation

The modular multilevel converter (MMC) always suffers from such a real problem in practice: the inductors and capacitors are changing with the operation temperature; and the large signal disturbance makes the equivalent resistance vary online. Therefore, an adaptive backstepping controller is proposed for the MMC application to cope with the strong nonlinear coupling characteristics and parameters variation online. Firstly, the uncertain parameters are introduced to establish the mathematical model of the MMC. Afterwards, the constructed Lyapunov functions are given to derive the control variables that satisfy the stability requirements utilizing the backstepping theory. At last, the feasibility and superiority of the designed nonlinear controller have been verified via the simulation.