Input/output feedback linearization control for three level/phase NPC voltage-source rectifier using its dual lagrangian model

This paper presents an input/output feedback linearization control strategy for the three-level three-phase neutral-point-clamped rectifier using it's dual Lagrangian modeling, which is obtained based on the superposition law, the load current and The Euler-Lagrange description of the rectifier. The load current can be given in two forms: 1. the load current involving the current of capacitor C1 and 2. The load current involving the current of capacitor C2 Applying the obtained load current to the Euler-Lagrange parameters of the rectifier, two nonlinear models of the system are derived. Also two the power-balance equations between the input and output sides are obtained by considering the effects of the two load currents separately. Then, the two nonlinear models and power-balance equations are linearized using input-output feedback linearization, and the state feedback law controlled inputs are completed by pole placement. With the definition of outputs of the feedback linearization law, the zero dynamics of the system are avoided and a fast output voltages control scheme is designed. Some integrators then are added to robust control against parasitic elements. The MATLAB/SIMULINK results verify the proposed control strategy.