Development of fanless high efficiency 30 kVA SiC-UPS

A fanless 30 kVA Uninterruptible Power System (UPS) has been developed using full silicon carbide (SiC) power modules. The SiC-UPS is equipped with natural air-cooled heat sinks designed based on thermal fluid analysis in order to improve the efficiency of heat transfer for a fanless system. The junction temperatures of the SiC device are sufficiently lower than the allowable junction temperature under the condition of 30 kVA of rated output power, and the fanless SiC-UPS has been confirmed to have adequate cooling performance. The fanless SiC-UPS achieves high power efficiency about 2.8% higher than that of our conventional forced air-cooled Si-UPS and about 0.7% higher than that of a fabricated forced air-cooled SiC-UPS. In addition, the power loss of its converter unit is successfully reduced by about 35% compared to our conventional forced air-cooled Si-UPS. These improvements are expected to make beneficial maintenance-saving of the UPS possible in an electric power system.