**Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical networks**

Winding arrangements can also, in part, bring an optimal behavior in the tradeoffs without any sacrifices, which play an important role in optimizing PT. Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical networks In the following work, four typical winding arrangements are compared to illustrate their advantages and disadvantages. individually shows their models. A full-bridge buck dc–dc converter employing these PTs has been built with the specifications presented in *Model A* Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical networks*: *Noninterleaving has very high ac resistance and leakage inductance, compared with other arrangements, as . However, it merits the stray capacitance because of only one intersection between the primary and the secondary.

Table II shows that the lowest stray capacitance can be achieved in the noninterleaving arrangement.*Model B*Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical networksBased on ac resistance and leakage inductance are dramatically reduced in general full-interleaving A lower MMF ratio *m *causes a weaker proximity effect in the adjacent layers, which contributes a lower ac resistance. The energy associated with leakage inductance is reduced due to the fact that the magnetizing force is reduced in each layer, as shown in However, seven intersections between the primary and the secondary can be found, which is caused by a higher stray capacitance.

## Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical network

As shown in Table II, the stray capacitance in is almost ten times that in noninterleaving. *Model *is another kind of fully interleaving arrangement, because the MMF ratios *m *in each layer are still equal to, as shown in Comparing with the general full-interleaving, Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical networks it has similar ac resistance and leakage inductance, because their MMF distributions have the same functions. However, it is very noteworthy that stray capacitance is getting better without sacrificing any other behaviors leakage inductance or ac resistance due to the fact that fewer intersections four between the primary and the secondary can be found.* Model *Model *d *represents an improved interleaving arrangement that constructs the top layer paralleling with the bottom layer and then in series with the other turns of the primary, so that the MMF ratio *m *can further be reduced. shows the analytical MMF distribution of . Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical networks Since the unavoidable error of impedances on the top and bottom layers, the currents in each branch are probably not equal, and hence, the MMF ratios *m *may not be Anyhow, a lower MMF ratio *m *below can be achieved.

Thereby, as shown in, a lower ac resistance appears in a high-frequency situation, and a slow increasing tendency can clearly be identified when the frequency is above. The most impressive thing is that not only ac resistance and leakage inductance can be reduced but stray capacitance can also be benefited, compared with other interleaving arrangements Spectrum defragmentation implementation based on software defined networking SDN in flexi-grid optical networks The paper proposed that quadruple interleaving also achieves by splitting the secondary. However, the even turn ratio is limited in this construction, and the stray capacitance might not be improved. the measured impedance with opening secondary winding in, and arrangements, respectively. The noninterleaving has the best parallel *LC *resonance frequency magnetizing inductance stray capacitance of primary, and the worst case occurs in the full-interleaving. Because the magnetizing inductance in the four arrangements are the same, the parallel *LC *resonance frequencies reflect the magnitude of the stray capacitors as the same results, as shown in Table kW full-bridge converter prototype employing the improved PT structure has been constructed, as shown in show the plots of the transformer primary voltage, primary winding current, and secondary voltage and current in different winding arrangements. In these figures, represent the voltage across the transformer