6.8 Heat

Outcome 8 of 8 in domain 6 · Power, panels, packs, motors, converters

What kills components: calculate it, remove it, measure it.

My targets

I declare:

Explain thermal resistance (°C/W) and the chain junction → case → heatsink → air, and calculate a junction temperature.
Read on a datasheet the maximum power, the temperature derating curve and the package’s thermal resistance.
Choose a heatsink for a given power, with or without a fan, and say what the paste, the insulator and the clamping do.
Measure a component’s temperature under load (thermocouple, camera) and compare to the calculation.
Explain thermal runaway in a bipolar transistor and why the MOSFET resists it better in parallel.
Predict the heat of a pack and a controller in a closed enclosure, and remove it (convection, conduction to the chassis, fan).
Diagnosis: a component that dies "for no reason" after twenty minutes, heat; the calculation after the fact and the measurement that would have predicted it.