The development of a 100 KHZ switched-mode power supply

Abstract

At the time of the design the maximum allowable operating frequency for an output power of between 200 and 250 watts was 100 kHz. Although a 600 kHz operating frequency could have been achieved, it would only be at a very low output power level. To maximise the current components available, a 210 watt 100 kHz direct-off-line switched-mode power supply was developed. The design presented can be used to power any compatible IBM XT/AT personal computer. The prototype was tested. An overall efficiency of 61% was achieved. The final prototype required 1 521 cm3 and weighed approximately 980 g, representing a power to volume ratio of 0.14 W/cm3 (2.26 W/inch3). Detailed procedures are also presented to help with the design and selection of the reactive components. Special design features include the half-bridge push-pull topology, MOSFETS as power switches, digital current limiting, primary power limiting, multiple outputs and fault counting to name but a few.