Research on Linear Output Voltage Transfer Ratio for Ultrasparse Matrix Converter

Abstract

Many existing researches of ultra Sparse matrix converter (USMC) show that the maximum linear output voltage transfer ratio (MLO-VTR)is less than 0.866, however, this paper proves that, based on space vector modulation(SVM), MLO-VTR for USMC can break the ultimate value. Firstly, based on the condition that input power factor is 1, the maximum output voltage within one carrier period and the maximum linear output voltage are derived. Further the mathematical equations among MLO-VTR, the output/input frequency ratios and the output voltage initial phase is also derived. After that, by solving the operating limits of the mathematical relationship of the MLO-VTR, we can obtain the maximum value of MLO-VTR under different output/input frequency ratios, which can be more than 0.866. Finally, all of theoretical derivations are verified by experiments.

Control method for the two‐stage matrix converter to enhance the linear voltage transfer ratio

“…It can be found from the operating principles of 3TSMC that the reactive component of the input current in (15), labelled as I rq , can be controlled freely, which provides an additional freedom to change the filtering capacitor voltages so as to regulate the VTR of 3TSMC. As can be seen from (15), the VTR can be increased by providing positive input reactive current (capacitive). Since the control range of the input reactive power in 3TSMC has no limit, in theory, the theoretical linear VTR of 3TSMC is infinite.…”

“…As can be seen from (15), the inductance of the inductor, the capacitance of the capacitor, the input reactive current component all have had effects on VTR. Therefore, the input filter parameters should be properly designed, aiming at obtaining an optimised input filter size.…”

“…where f c is the cut-off frequency of the input filter. Then, assuming a maximum VTR of 1 is required in rated condition, the maximum reactive input current I rq can be solved according to (15). Finally, the volume models of the capacitor and inductor can be established as…”

“…However, the relatively low voltage transfer ratio (VTR) is one of the major drawbacks of the three-phase-to-threephase TSMCs, especially when TSMCs are applied in AC adjustable speed drives (ASDs), power supplies, and power systems and so on. Usually, there are two solutions to improve the VTR: one is altering the topology of TSMCs to boost the output voltage [7][8][9][10][11][12][13]; the other is applying modulation strategy to enhance the VTR [14][15][16][17][18][19].…”

“…In [14], a modulation strategy that improves the VTR of a matrix converter operating with non-unity input power factor was suggested, which is able to obtain higher VTR when compared with the traditional strategies. Based on the space vector modulation (SVM), Xia et al [15] investigated the derivation about the VTR and proved that the theoretical maximum linear VTR can reach 0.928 when the output frequency and initial phase are the same as those of the input side. The authors of [16][17][18][19] focused on the improvement of VTR by operating TSMCs in the over-modulation region.…”