There are losses in every step, and power supply design is basically a big optimization problem to choose all the design parameters to minimize losses.
The main components with losses:
* The input capacitors are non-ideal and have some resistance. That resistance causes heat every time current flows in or out of them.
* The MOSFET switch has an 'on resistance' which means it wastes energy when current flows through it.
* The MOSFET takes a certain time to turn on or off. During that time it is partially on, which wastes a bunch of energy each switch.
* The transformer has resistance in the coils.
* The transformer has iron core hysteresis, which makes the steel of the transformer get warm as magnetic fields change in it.
* The diode on the output side has voltage drop across it.
* The capacitor on the output side has resistance.
Re:Teardown of a PC Power Supply
by quercusa on Sunday May 23, 2021 @03:48PM
(#27257946)
It was a real learning experience moving from ideal transistors to real MOSFETs in an H-bridge driving a motor. Gate capacitance led to lots of expensive smokefests.
The main components with losses:
* The input capacitors are non-ideal and have some resistance. That resistance causes heat every time current flows in or out of them.
* The MOSFET switch has an 'on resistance' which means it wastes energy when current flows through it.
* The MOSFET takes a certain time to turn on or off. During that time it is partially on, which wastes a bunch of energy each switch.
* The transformer has resistance in the coils.
* The transformer has iron core hysteresis, which makes the steel of the transformer get warm as magnetic fields change in it.
* The diode on the output side has voltage drop across it.
* The capacitor on the output side has resistance.