Switching Power Supplies A - Z, 2nd Edition

Chapter 11

Thermal Management

This chapter goes into the critical issue of thermal management of power converters and reduction of thermal stresses. Historical “ideal” definitions of thermal resistance and convection coefficient are first provided. Then, real-world divergences based on higher-power dissipations and large exposed areas are revealed. The multitude of seemingly different empirical equations found in literature are compared with each other and with the heat transfer equations derived theoretically from thermodynamics. They are shown to be all very similar, and thus the equations for conservative design estimates are identified. The equations for sizing plate heatsinks are then applied to the exposed copper area onBs as a rough guide ...