WEG MVW3000 A0040 V023, User Manual

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MVW3000 | 3-5
3
MVW3000 | 3-5
Product Characteristics
3.3 CONNECTION OF THE CELLS
To form a three-phase output, a number “n” of power cells that operate with 690 “V
rms
” of output are rms grouped
in series per phase. The cell sets that represent phases U, V and W are connected in star configuration, with a
floating neutral in common with the phases, as indicated in
Figure 3.5 on page 3-5 .
n x 690 V
690 V
V
W
U
√3 x n x 690 V
Vn
V2
V1 W1
W2
Wn
U1
U2
Un
Figure 3.5: Cell-to-phase connection diagram
Figure 3.6 on page 3-6 shows the transformer, input switchgear and secondary winding connected to each
cell. This association in series enables more voltage levels at the inverter output. Locally, each cell produces three
voltage levels; however, at the converter three-phase output, it is possible to obtain 2n + 1 levels on the phase
voltage and 4n+1 levels on the line voltage.
This effect occurs, because the voltage of each phase is instantaneously given by the addition of the voltages at
terminals FA and NE of each cell pertaining to the analyzed phase.
Figure 3.7 on page 3-7 shows the sum of
the voltages of each cell to form the phase voltage in a 9-cell MVW3000 (3 per phase).