The wind power converter with parallel structure can increase the capacity to the megawatt level

so it is widely used in the wind turbine. Because of the wind power fluctuation

the current of the power semiconductor device with its drive power is fluctuating largely and rapidly

which will cause a large junction temperature variation

affecting the lifetime of power semiconductors and the reliability of the converter

but the reliability is the key issue for the wind power converter. Aiming at it

the thermal smooth control for megawatt parallel wind power converter has been proposed in this paper to improve the converter’s thermal reliability. With the proposed thermal smooth control method

extra reactive power is introduced to the converter

and the reactive current smooth the thermal stresses of power semiconductor devices when the wind speed slow down. So the junction temperature variation become smaller

and the lifetime power semiconductor devices become longer

and the wind power converter’s reliability improved.Finally

a simulation platform based on MATLAB/PLECS is built

and some calculations have been done with the 3MW parallel wind power converter. The simulation results show that when the load of the converter changes

the temperature fluctuation of IGBT is changed from 34 ℃ to 12 ℃.