technique is the method that was created to optimize the energy
storage of the prefluxing device given a specific transformer
size.
B. Volt-Second Design Method
1) Theory: The Volt-Second method is based upon transformer
design and operating principles. Fig. 4 contains plots of
the laboratory transformer waveforms during rated and opencircuit
operation.
The traces on the left, starting at the top, are the transformer
voltage, the transformer core flux, and the transformer magnetizing
current. The voltage measurement was taken by using a
search coil, and the flux waveform was produced by integrating
the voltage. A Hall-Effect current transducer was used for the
current measurements. LabVIEW was used to plot the signals
[1]. The plot on the right of Fig. 4 shows the corresponding I
curve during rated, open-circuit operation, made by plotting the
magnetizing current waveform on the axis and the core flux
on the axis.
The curve of Fig. 4 indicates that the transformer is designed
so the peak core flux is close to the knee of saturation
curve. Operating the transformer around the knee makes
the most efficient use of the energy transfer capabilities of the
magnetic core while still keeping the magnetizing current and
core losses at reasonable levels, when compared with operating
further in saturation, as Fig. 3 demonstrated.
From Fig. 4, the flux of the transformer is the integral of the
voltage waveform, which has equivalent units of volt-seconds.
Beginning integration at the peak of the rated voltage waveform,
when the flux is zero and integrating for a quarter period (shaded
region), yields a peak rated flux in the transformer’s core and a
corresponding peak rated magnetizing current. Consequently, if
the prefluxing device stores enough energy to transfer an equal
number of volt-seconds to the transformer as occurs during a
quarter period of rated transformer operation, the device will
flux the transformer under conditions similar to rated operation,
resulting in maximum fluxing without unnecessary energy
waste, which is the aim of the Volt-Second design method.
Mathematically, the volt-seconds during a quarter period of
rated operation are given as follows:
technique is the method that was created to optimize the energy
storage of the prefluxing device given a specific transformer
size.
B. Volt-Second Design Method
1) Theory: The Volt-Second method is based upon transformer
design and operating principles. Fig. 4 contains plots of
the laboratory transformer waveforms during rated and opencircuit
operation.
The traces on the left, starting at the top, are the transformer
voltage, the transformer core flux, and the transformer magnetizing
current. The voltage measurement was taken by using a
search coil, and the flux waveform was produced by integrating
the voltage. A Hall-Effect current transducer was used for the
current measurements. LabVIEW was used to plot the signals
[1]. The plot on the right of Fig. 4 shows the corresponding I
curve during rated, open-circuit operation, made by plotting the
magnetizing current waveform on the axis and the core flux
on the axis.
The curve of Fig. 4 indicates that the transformer is designed
so the peak core flux is close to the knee of saturation
curve. Operating the transformer around the knee makes
the most efficient use of the energy transfer capabilities of the
magnetic core while still keeping the magnetizing current and
core losses at reasonable levels, when compared with operating
further in saturation, as Fig. 3 demonstrated.
From Fig. 4, the flux of the transformer is the integral of the
voltage waveform, which has equivalent units of volt-seconds.
Beginning integration at the peak of the rated voltage waveform,
when the flux is zero and integrating for a quarter period (shaded
region), yields a peak rated flux in the transformer’s core and a
corresponding peak rated magnetizing current. Consequently, if
the prefluxing device stores enough energy to transfer an equal
number of volt-seconds to the transformer as occurs during a
quarter period of rated transformer operation, the device will
flux the transformer under conditions similar to rated operation,
resulting in maximum fluxing without unnecessary energy
waste, which is the aim of the Volt-Second design method.
Mathematically, the volt-seconds during a quarter period of
rated operation are given as follows:
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