Water-cooled switching power supply

The authors describe a novel water-cooled switching power supply that is one-third of the size of the conventional air-cooled 2.2 kW power supply. A size reduction of one-third makes it possible to locate the supply nearer the logic circuits. To achieve this size reduction: (1) the size of the output filter was reduced and a forward two-phase switching PWM (pulse width modulation) topology with a switching frequency of 200 kHz was used; and (2) the main switching elements and output diodes are water-cooled using the same coolant that is used for the logic circuits. Since these elements account for as much as 70% of the overall losses in a switching power supply, this technique resulted in a better than 83% reduction in the volume of the heat sink. The performance of the switching power supply is described, with emphasis on the circuit and the cooling system.<>