Integral sliding mode current control for three phase voltage source rectifier under unbalanced input voltage conditions

In this paper, a robust current control strategy for three-phase voltage source rectifier (VSR) under unbalanced input voltage conditions is proposed. In the strategy, dual current control structure with current regulation performed in positive and negative sequence (PNS) synchronous reference frame (SRF) is used and negative sequence current compensation is adopted to attain constant dc link voltage and sinusoidal ac line current. With regard to the current control law, power and flexibility of sliding mode control (SMC) and the Lyapunov stability theory is fully exploited and an enhanced SMC with integral action in both the sliding manifold and control law (ISMC) is obtained to solve the non-zero steady state error problem that faced in practice by conventional SMC (CSMC). As such, satisfactory performance can be obtained and system robustness can be guaranteed in the Lyapunov sense, in the presence of uncertainties with known bounds. Effectiveness of the ISMC current control strategy is verified through simulation and comparative study on a VSR model with MATLAB/SIMULINK.