Control of IGBT junction temperature in small-scale wind power converter

In wind power converters, the junction temperature of the power module is the crucial factor which affects its reliability. This paper developed a comprehensive thermal management strategy to improve the operational reliability of a small-scale wind power converter. Theoretical analysis, simulation and frequency conversion experiment are given to verify the effectiveness. And the specific goal of thermal management has also been investigated. Firstly, the idea of thermal management which combines the reliability as well as the stability is introduced. Then, in order to smooth the temperature fluctuations, the flexible continuous adjustment of the switching frequency and the exterior thermal management method are applied. A FPGA based temperature-controlled oscillator and fan speed regulator are designed. Lastly, numerical simulation was carried out to verify the correctness of the proposed thermal smooth control method. Meanwhile, the rain-flow counting method and Miner´s linear cumulative damage law are applied to check whether the goal is achieved or not, from the system reliability point of view. This study shows that the thermal management is not mean only to suppress the fluctuation of the IGBT junction temperature as much as possible. But full consideration should be given for both the temperature fluctuation as well as its average value, so as to improve the reliability and to extend the lifetime of the power converter.