Design of 150°C DC-DC Converter Based on Flyback Topology for Downhole Drilling Equipment

High temperatures in unconventional oil and gas reservoir present a challenge to DC-DC converter design for downhole drilling equipment. In response to the high-temperature challenge, a design methodology consisting of controlling-junction temperature rise, derating component electrical parameters for more design margin and selecting high-temperature components was proposed. Based on the methodology, a converter board with a nominal input of 42-54V and output of three low voltages (+15V, -15V, and +5V), was designed for the 150 degrees C application. The maximum temperature rise of the components in the converter prototype under a temperature environment of 22 degrees C is 11.9 degrees C. The performance of the converter was verified at the ambient temperature from 30 degrees C to 150 degrees C. With a 42 similar to 54V input voltage, the output voltages have less than 0.2V fluctuation; the three output voltages can achieve a ripple suppression ratio of approximately 40dB, and the average conversion efficiency was around 75% at 150 degrees C, which meets the design specification.