f. The output is increased when four diodes are used to provide full wave
rectification (fig 32). Note that the current is more continuous than with one
diode, but that the current varies from a maximum value to a zero value. It is
particularly important to observe that the current flow through the external load
resistor is in one direction only (fig 30 and 31). The AC voltage and current
have, therefore, been rectified to a unidirectional or DC voltage and current.
This circuit arrangement could be used to charge a DC battery, but it does not
produce the most output that can be obtained in a generator.
Figure 32.
Full-wave rectified voltage.
g. In order to obtain a
higher output and smoother voltage and' current, a
three-phase stator is connected
to six diodes which together form a three-phase,
full-wave bridge rectifier (fig
33). A battery connected to the DC output terminal
will. have its energy restored
as the generator provides charging current. Note
that the blocking action of the
diodes prevents the battery from discharging
directly through the rectifier.
Figure 33.
Three-phase, full-wave rectifier.
h. The voltage obtained from the stator-rectifier combination, when
connected to a battery, is not perfectly "flat" but is so smooth that for all
practical purposes the output may be considered a nonvarying DC voltage. The
voltage is obtained from the phase voltage curves (fig 34).
Figure 34.
Three-phase, full-wave rectifier output voltage.
OS 010, 1-P17
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