High temperature Power Module for electrical switching applications.
A high temperature, small form-factor bridge leg power module has been developed by Raytheon UK.
Aimed at high speed switching applications, the module has potential uses in the aerospace sector as it requires minimal external cooling and presents considerable weight saving opportunities within the More Electric Aircraft power system. Also, by supporting applications in harsh environments and in meeting high operating temperature demands, the module can also be used in the geothermal power and oil and gas sectors.
A prototype module has currently amassed more than 1,000 hours of stable operation at 300 degrees C. Tests on the module, which includes two 1,200V silicon carbide (SiC) bipolar junction transistors (BJTs), have been performed switching 500V at room temperature and switching 200V at 300oC. The BJTs are controlled by integrated base driver circuitry, made using Raytheon’s propriety high temperature silicon carbide (HiTSiC) process.
“The co-location of BJT base driver circuitry and power transistors into a single high temperature module is a major industry breakthrough,” said David Gordon, technical lead, Raytheon’s IPS. “In many instances it is necessary to switch power stage transistors at tens of kHz and that requires getting the base driver circuitry as close as possible to the power transistors. However, in a high temperature environment that presents a problem.
“While silicon carbide transistors can switch high voltage and handle high temperatures, traditional silicon-based gate driver circuitry cannot cope with the heat. Silicon on Insulator raises the bar to about 220 degrees C, but that’s still not high enough for some existing and emerging applications for power electronics. Raytheon’s HiTSiC CMOS circuitry on the other hand was designed to operate at 300oC, and has been tested at considerably higher temperatures.”
The module is packaged in a 32pin hermetic dual in line (DIL) ceramic package measuring approximately 40mm x 23mm.