may i know what is the purpose of finding power devices losses??
What do you mean by 'power device' ?
It could be an electric drill or it could be a computer.
The designer of the device will need to consider energy wastage as heat, amongst other things, in order to choose suitable components with which to build the device.
my power device is refer to SiC IGBT
Because power losses equate to the heat dissipated in the device. We need this information to design suitable heatsinking and cooling, to keep the devices within their safe operating temperature range.
may i still know what is the purpose of finding: Pon, Poff, Pon-state, Pswitching and Ptotal??
They are just the various components of the total energy loss that we need to account for when determining the total power loss.
The total energy loss per cycle generally consists of the on state losses plus the switching losses. The switching consist of the "turn on" losses plus the "turn off" losses.
Adding all of the various energy losses together gives the total energy loss per cycle, and multiplying this by the switching frequency gives the average power loss - which is essentially the rate at which we need to remove heat.
I deal with this issue daily - the devices have a max temperature they can survive, if they generate more heat than you can dissipate - they will fail. ( There is of course the other issue of system efficiency) .
It is a constant struggle to get EEs to really pay attention to how effective their cooling ( heat dissipation is) - it is very common for EEs to use a Fixed Heatsink Temp of 80C - then the Heatsink supplier has to provide a HS that can dissipate X watts of heat to an ambient Temp Y - this is fine for the first pass evaluation but not for any type of an optimized system (not to mention determining lifetime!). When I meet a new EE on a new project and I ask what is your Rth and I get a blank stare - I know it will be a long road to get good information to help them succeed in their job of selecting the best device.
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