Abstract
The temperature fluctuations in the semiconductor devices within NPC wind power converter during low-voltage ride-through operation is critical in reducing the lifetime cycle of the converter and hence the wind power system. Moreover, the unbalanced voltage sags in three phases may cause unbalanced temperature fluctuations, which makes the power loss balancing among different phases necessary. In this paper, a carrier-based modulation technique is proposed to address this issue. The temperature fluctuations in semiconductor devices among three phases can be balanced, and the largest temperature fluctuation will be reduced. Simulation results are presented to verify the effectiveness of the proposed technique.