Improved Third-Harmonic Injection Two-Stage Matrix Converter Topology Based on Decomposition Control of Injection Current

In this article, an improved topology of the third-harmonic injection two-stage matrix converter (3TSMC) is proposed, which not only ensures that the input reactive power control capability is independent of the voltage transfer ratio (VTR) and the load conditions but also achieves high-quality mains current waveforms. To solve the problem of injection current control error in nonunit input power factor operation of 3TSMC, the third-harmonic injection current is decomposed into the active and reactive components, which are, respectively, controlled by the original injection current control bridge arm and an additional bridge arm named reactive power control bridge arm (RB). The maximum current of the inductor of RB is equal to the absolute value of the required input reactive current amplitude and will not increase with the increase of the VTR. The design criteria of the inductor of RB are discussed. To ensure the closed-loop stability under two injection directions, the controller of the injection current reactive component is designed. The effectiveness of the proposed topology and control strategy is verified by the experimental results.