Neil R. Sorensen

Thermal Study of Inverter Components

Thermal histories of inverter components were collected from operating inverters from several manufacturers and three locations. The data were analyzed to determine thermal profiles, and the dependence on local conditions, as well as to assess the effect on inverter reliability. Inverter temperatures were shown to increase with the power dissipation of the inverters, follow diurnal and annual cycles, and have a dependence on wind speed. An accumulated damage model was applied to the temperature profiles, and an example of using these data to predict reliability was explored.

A Novel Millimeter Wave Corrosion Detection Method

In this paper, a new electromagnetic method is developed for detecting corrosion as well ad determining the thickness, rate of accumulation, and electrical properties of the modified material. This noncontact method uses a Gaussian resonator operating in the range [approximately] 20-200 GHz. In fact, a window can separate the sample and the measurement electronics allowing in situ diagnostics. Experiments have been done on the oxidation of Fe and the sulfidation of Cu and Ag. The growth thicknesses determined from this technique agree very well with those calculated from mass change or quartz crystal resonance data. The electrical properties calculated for the sulfide growth layers also agree reasonably well with published values.