## 2 Suggested Topology and Its Operation
### Shoot through Elimination  
The polarity of the input voltage has an effect on its operation as well as on the output voltage gain. Therefore, the operating behavior during shoot-through intervals is discussed with respect to the polarity of the input voltage. The elimination of the shoot-through during the positive and negative inputs once all the controlled switching units are on is demonstrated with the help of all possible current loops in Figure 3a,b respectively.  
The cathodes of the diodes \"_D1\"_, \"_D3\"_ and \"_D2\"_, \"_D4\" are connected to the same node so their cathode potentials are equal. In this scenario, the diode will conduct the current if its anode voltage is greater than the anode voltage of the other diode that is cathode connected with the cathode of the first one. For example, operation during the positive input as shown in Figure 3a, the anode terminals of the diodes \"_D1\"_, \"_D4\"_ and \"_D3\"_\"_D2\"_ are connected to positive and negative terminal of the source respectively. In this case, the diodes \"_D1\"_ and \"_D4\"_ operate in forward biased mode and corresponding current loops are depicted in Figure 3a. In the same way, the anode voltage of the diodes _D2_, _D3_ and _D1_, _D4_ are positive and negative respectively as can be seen in Figure 3b. In this condition, the diodes \"_D1\"_ and \"_D4\"_ cannot conduct and the currents loops shown in Figure 3b are owing to the conduction of diodes \"_D2\"_ and \"_D3.\" It can also be viewed  
Figure 2: Schematic view of the suggested topology.  
in Figure 3 that there are always two current conduction loops during the shoot-through periods that ensure the non-interruption of the inductive current. This characteristic also reduces the current rating of the semiconductor devices during shoot-through intervals. Another point can be viewed that among the six controlled switching units, there are two groups of switching transistors with three transistors in each group. The transistors of each group require the same control signal so any operating mode of the proposed topology can be realized with two switching signals only.  
By nature, these signals are complementary and a turn-off delay angle or shoot-through angle (\(\theta_{o}\)) ensures the safe operation by resolving the inductor current interruption challenge as depicted in Figure 4. The proper value of this delay can also be used to adjust the boost factor (\(\beta\)) in high output frequency operation as well. In this interval, the voltage across the intermediate inductor can be calculated in Equation (1) by ignoring the voltage drops in the controlled and uncontrolled switching units.  
\[V_{ind}\ =\ \theta_{o}V_{in} \tag{1}\]  
Similarly, the inductor voltage during the non-shoot through angle is formulated as,  
\[V_{ind}\ =\ \theta_{c}(V_{in}-V_{o}) \tag{2}\]  
The dc or average value of the inductor voltage during a conduction angle (\(\theta_{p}\)) is obtained by using Equations (1) and (2).  
\[\frac{\theta_{o}V_{in}+(V_{in}-V_{o})\theta_{c}}{\theta_{p}}\ =\ 0 \tag{3}\]  
That may be reduced to the following equation.  
\[\frac{V_{o}}{V_{in}}\ =\ \frac{\theta_{o}+\theta_{c}}{\theta_{c}}\ =\ \beta\cong 1 \tag{4}\]  
Figure 3: Currents loops during shoot-through operation for (**a**) positive input and (**b**) negative input.  
For low output frequency, the value of the overlapping or shoot-through angle is not comparable to the non-overlapping angle, so in those cases, the voltage gain or boost factor is approximately unity. Practically it may be less than unity due to voltage drops in the switching units. The boosting characteristics can only be achieved for some limited outputs. So, the basic role of the turn-off delay angle is to avoid the challenge of inductive voltage kicks that may be developed due to inductor current interruption.