Life estimation modelling has the potential to become an effective way to optimise the maintenance and replacement schedules of power electronics used in variable speed wind turbines. In this presentation, a model is proposed to estimate the loss of life of power electronics in operation. This life estimation model takes into account the main types of failure mechanisms of power electronics. It incorporates the dynamic load profile under variable wind speed operation into the device lifetime deduced from manufacturers’ power cycle tests. It can be used as a method to assess the fatigue damage accumulated during the dynamic load profile and predict the end-of-life of power electronics.