Hi there,
In addition to the power dissipation which is usually an important issue, there is also the 'catch' diode reverse recovery period issue to think about. That's the time when the catch diode has to recover from being forward biased and the power to recover comes from the MOSFET being switched 'on'.
One of the ways to handle this is to limit the turn on time of the MOSFET so that it turns on gradually rather than abruptly, but not so slowly that it causes too much power dissipation. The technique usually involves a small resistor in series with the gate such as 10 or 20 ohms.
Another way is to use a 'zero' recovery time diode.
BTW, you can estimate the power loss in the MOSFET during the switching period due to the switching itself with this formula:
P=Imax*Vmax*Tp*F/3
where
Imax is the max current, and
Vmax is the max voltage, and
Tp is the switching period, and
F is the switching frequency
For an example, say we have a MOSFET switching at 10kHz and each switch period is 10us long, and the max current is 50 amps and the max voltage is 100 volts, that would mean 167 watts would be dissipated in the transistor just because of the on/off switching itself. That would probably be too high so the design would have to be improved.
Note that in that formula the MOSFET switches twice per cycle, once 'on' and once 'off', both of which dissipate power.