Harmonic Suppression and Stability Analysis of Three-phase VSR with Cosine Internal Model Control Strategy

In this paper, low-frequency harmonics of grid current in the three-phase voltage source rectifier (VSR) are analyzed. It indicates that dead-time effect, harmonics in drive signals and harmonics in grid voltage are the main reasons why harmonics exist in the grid current. Furthermore, a self-adjusting control strategy in current loop is proposed to suppress specific harmonics based on cosine internal model (CIM) control strategy. The system stability is effected by the added controller, and its stability boundary is calculated by Jacobian matrix, which gives constraints to design the controller parameters. Tested waveforms prove that harmonics can be suppressed by the proposed control strategy, and the numerical analysis is correct.