Sensitivity analysis of switching electrical parameters of semiconductor devices for wind turbine converters

The failure of power converters is currently the main reason of stopping for wind turbines. The unpredictable nature of wind power flow causes temperature swings to the semiconductor devices, which leads to additional thermal stresses and, eventually, unexpected failures. A suitable way to avoid this is using condition monitoring systems, which detect the degradation of the devices and reduce the stopping time by a planned maintenance. The choice of the most appropriate early failure detector is therefore essential to make sure that the condition monitoring system is accurate and indicates a fault only when this is actually occurring. For this reason, this paper focusses on the sensitivity analysis of switching parameters in response to a variation of the load and the dc-bus voltage, which may introduce uncertainty in the detection of early fault as they have a direct influence on the device temperature. The results of the experimental investigation show a substantial sensitivity of switching parameters to dc-bus voltage variation and a moderate sensitivity to load variation.