A Comprehensive Modulation Strategy for the Neutral-Point Clamped Wind Power Converter Thermal Management During Low-Voltage Ride Through

The temperature fluctuations in the semiconductor devices within neutral-point clamped (NPC) wind power converter during low-voltage ride-through operation would reduce the lifetime cycle of the converter and jeopardize the reliability of the wind power system. In this article, a thermal management strategy based on carrier-based modulation techniques, i.e., zero-sequence and dipolar injections, is proposed to address this issue. The temperature fluctuations in semiconductor devices among three phases can be reduced and balanced. Besides, the neutral-point voltage balancing can be guaranteed. Simulation and experimental results are presented to verify the feasibility and effectiveness of the proposed technique. Its influences on the converter total power loss and output current harmonics are discussed as well.