How to determine maximum switching frequency of power modules?

Power IGBT and MOSFET modules give some datasheet values that look like they could be used to calculate a maximum frequency, but I'm not sure how to interpret them to do so.

The datasheets generally have four timing parameters: turn-on delay time $$\T_{D,on}\$$, rise time $$\T_r\$$, turn-off delay time $$\T_{D,off}\$$, and fall time $$\T_f\$$. My first guess is that the minimum switching period would be simply $$\T_{D,on} + T_r + T_{D,off} + T_f\$$.

Just adding all these together can't be right, though, since for an IGBT module that I'm considering using for a project it produces a max switching frequency of over 2 MHz, far above anything I at least would consider feasible. Running this module at 2MHz would result in switching losses that exceed its maximum power dissipation by two orders of magnitude! Is the switching frequency instead limited solely by power and thermal considerations?

• I think the turn on and turn off delays shouldn't be simply added. If there were only a turn on delay and turn off delay, both of equal length, the input period of the driving signal would equal the switching period. The switching period would be only delayed in time with respect to the driving signal Mar 3, 2019 at 14:13
• @Huisman Right, but as doing the computation that way gives results that are just plain absurd (25kW power dissipation in a 250W module!), I would assume that adding up times like that isn't the proper way of doing it anyway. Mar 3, 2019 at 14:17
• Not want to spoil it, but this IGBT has Features - "Switching frequency up to 20 kHz". (I've been taught IGBT's are suitable for high voltage, but low frequencies wrt mosfets lower max voltage, higher frequency. But IGBT's have improved much lately) Mar 3, 2019 at 14:21
• But I'm still curious for the answer in general Mar 3, 2019 at 14:22
• @Huisman Well, I suppose I chose the wrong datasheet to use as an example! I didn't realize this particular one specified a frequency. Still, in general they don't seem to, so I feel the question is still worthwhile. Though... With the switching energy this module lists (32mJ per cycle), 20kHz would still be dissipating 640 watts just in the switching losses, which is itself more than twice the rated power.... Huh. Mar 3, 2019 at 14:49