Experimental Investigation of Gallium Nitride Power Semiconductor Performance for High-Frequency DC-DC Converter Applications in Nigerian Climate Conditions

This study experimentally investigates the performance and reliability of gallium nitride power semiconductor devices in high-frequency DC-DC converter applications under the elevated ambient temperature and humidity conditions characteristic of Nigerian climate zones, assessing the readiness of GaN technology for adoption in Nigerian power electronics applications. GaN power transistors offer significantly superior switching speed, on-state resistance, and thermal performance compared to silicon MOSFETs, enabling higher frequency converter operation and reduced passive component sizes, but their performance and long-term reliability under tropical conditions relevant to Nigeria require experimental validation. GaN-based half-bridge power stage converters operating at 1MHz switching frequency and rated at 48V, 10A were constructed using commercial GaN transistors from two manufacturers and characterised in a temperature and humidity controlled environmental chamber set to conditions representing Lagos coastal humid tropical, Kano hot dry, and Jos highland temperate profiles. Switching energy losses, on-state resistance, gate threshold voltage, and thermal resistance were measured over 1,000-hour accelerated ageing periods under each climate profile. Efficiency measurements across load range were compared against matched silicon MOSFET converters under identical conditions. Results confirm that GaN converters achieve 96.8 to 97.4 percent conversion efficiency at full load, 2.1 to 2.8 percentage points above silicon at the same switching frequency. Degradation of gate threshold voltage was most pronounced under the humid coastal conditions, suggesting that moisture ingress management in packaging is critical for tropical deployment reliability. Keywords: gallium nitride, power semiconductor, DC-DC converter, tropical reliability, Nigeria.