Hybrid Modulation Strategy for Two-Stage Matrix Converter and its Application in Vector Control of Doubly Fed Induction Generator

Abstract

A hybrid modulation strategy (HMS) for a two-stage matrix converter (TSMC) is presented in this paper. According to the variation of voltage transfer ratio, different combinations of modulation modes for rectifier-side converter (RSC) and inverter-side converter (ISC) of TSMC are adopted. Two different current space vector modulation methods are used for RSC to obtain maximum and minor DC voltages. The power loss of TSMC is reduced based on the minor DC voltage. In addition to the linear space vector modulation for ISC, an overmodulation method is presented in order to increase the voltage transfer ratio of TSMC. HMS ensures smooth switching between different modulation modes and makes the best use of the advantage of these modes. Finally, HMS is applied in the case where TSMC is used as an AC-excitation converter for doubly fed induction generator (DFIG) to achieve maximum power point tracking (MPPT). The simulation results confirm the accuracy and feasibility of HMS and the good performance of the MPPT operation of DFIG excited by TSMC.