EMC Question of the Week: August 14, 2017
When laying out power electronics circuits, it is important to identify the switching current loop. The switching current loop
- always passes through the inductor
- always passes through the switch
- always passes through the output filter capacitor
- all of the above
Answer
The correct answer is "b". The switching current loop is the path of the currents that must have a high di/dt in order to ensure efficient operation of the inverter. It is generally important to minimize the loop area associated with this current path. The components that are part of this current loop vary depending on the type of inverter, but the components responsible for the current switching are always part of the loop.
The inductor is never part of the loop, because inductors resist sudden changes in the current flowing through them. Output filter capacitors may be part of the loop in some power circuits (e.g. boost converters), but they are not always part of the switching current path.
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