In case of several wind generator placed in the same area , how their output are electrically combined ?
For example 3 wing generators placed in the same field , how their electrical output are combined into one
single voltage so it will be used to drive the battery charger .
One way I thought is to rectify each generator output and use blocking diodes
to feed the charger in parallel .
If its a big installation there are specialized inverter/controllers that will do power-point tracking to get maximum power from each into the main bus. For a smaller setup you might try something simpler like paralleling the outputs - rather assumes the generators are identical in identical atmospheric environments. The engineering involved depends on a lot of factors.
Sounds like you are thinking of several small wind generators for battery charging. If they supply DC the most you should have to do is put a large enough diode in each supply line so they can't back feed. This may not be necessary, depending on the design of the generators.