Two-stage Matrix Converter Of High Performance Modulation Strategy

Dual-stage matrix converter (DSMC) is a power electronic converterwith new topology developed on the basis of conventional matrixstructure. It has the same excellent advantages as the conventional matrixconverter (CMC), such as two-way circulation of the energy, sinusoidalinput/output voltage and current wave forms, controllable input powerfactor, compact structure etc. At the same time, DSMC overcomes theshortcomings of CMC, such as huge clamp circuit and complex switchingcommutation control. So it is a very potential power converter.But there are two problems of DSMC: 1. the maximum voltagetransfer of DSMC is just 0.866; 2. DSMC has many switches operatingon high frequency, so the conduction and switching losses of DSMC arelarge.The paper analyses mathematics dual-stage matrix topology,operation mechanism and the conventional modulation algorithm. Aimingto solve the low voltage transfer ratio problem of the conventionalmodulation method, an overmodulation method to enhance voltagetransfer ratio of dual-stage matrix converter is proposed without changingthe original topology.Then the conduction and switching losses of DSMC are analyzed. Anovel modulation method to reduce the switching losses is proposedbased on previous analysis. The switching losses are minimized byemploying the lowest and the second larger input line-to-line voltage forthe synthesis of the DC link voltage. The comparison of losses analysesbetween conventional modulation method and lower-losses modulationstrategy demonstrate the accuracy of the latter modulation.A practical hybrid modulation strategy based on three modulationmethods has been presented. The hybrid modulation method keeps thedual-stage matrix converter on good performance and improves thepracticability of it.The simulation and experimental results confirm the accuracy andfeasibility of all modulation methods the paper proposed.