Can we consider unfolding stage of flyback inverter as a half bridge ?
6:26 AM
The flyback inverter secondary winding acts as an unfolding stage in a grid connected scnario. The switches associated with them needs gate driver circuits. The question here is that can we consider them as a half bridge circuit so that it is possible to use a half bridge driver ic with it. To answer this consider the Fig. 1 that depicts two different types of unfolding configurations. The working although is same lets consider the one with no center tapping.
 |
| Fig 1: Flyback inverter secondary configurations. |
If we redraw the circuit as shown in Fig 2. it seems like a duplicate version of a half bridge converter. However, considering the negative half cycle of grid voltage where we have to switch Sac2, the current has to pas through the Sac1 as well as Sac2 thus creating a dead short circuit. This can be seen in Fig. 2
 |
| Fig 2: Wrong imagination of the flyback unfolding stage. (Click to zoom) |
In fact there are two secondaries hence the correct circuit looks like Fig.3. It is clear that an ic that is made specially for half bridge configuration (like IR 2111) cannot be applied here. Separate control ic for high side Sac1 and low side Sac2 are required.
 |
| Fig 3. Correct immagination of flyback unfolding stage. (Click to zoom) |
Hence the unfolding stage of flyback inverter and the half bridge are not the same.
0 comments