The feasibility study on thermal loading control of wind power converters with a flexible switching frequency

Thermal loading of wind power converters is critical to their reliability performance. Especially for IGBT modules applied in a converter, both of the mean value and variation of the junction temperature have significant impact on the lifetime. Besides other strategies to reduce the thermal loading of the IGBT modules, the power losses and thereby the thermal stresses can be controlled by varying the PWM switching frequency according to power loading conditions. This paper investigates the feasibility to apply this flexible modulation strategy in a 3 MW wind power converter application to reduce the temperature fluctuations due to wind speed variations. The trade-off between the reduced amplitude of temperature fluctuations and the additional power losses that may be introduced is quantitatively studied.