to charge the capacitor. Plugging these quantities into (4) reveals
that a capacitance of roughly 3.9 mF is needed to properly flux
the transformer.With the desired capacitance and initial voltage
level, the total energy ideally stored in the capacitor is approximately
1.75 J. The operation of Fig. 5 actually used a 4-mF capacitor,
the closest capacitance to the desired amount that was
available in the lab.
A detail to note in Fig. 5 is that the peak level of the current
during the device operation is approximately 55 A, which
is the same as the peak magnetizing current drawn by the transformer
in steady-state, open-circuit operation (Fig. 4), demonstrating
that the Volt-Second design method does an excellent
job of fluxing the transformer under conditions similar to the
rated transformer operation.
It is worthwhile to mention that the transformer inductance
used in the preceding equations is not a constant value, as the
slope of the curves in Fig. 3 demonstrated. If the prefluxing
operation forces the transformer flux further past the knee point
then what occurs under rated operation, is reduced in value
and the resonant frequency increases, decreasing the volt-seconds
delivered to the transformer.