Combined Model Predictive Control Strategies to Improve the Reliability of IGBT Module in Doubly Fed Wind Power Converter

The reliability of the rotor side converter of doubly fed induction generator (DFIG) could be greatly degraded due to large junction temperature fluctuation and high power loss, a combined model predictive control strategy is proposed to reduce the junction temperature and switching loss. First, based on the structure of IGBT modules in DFIG wind power converter, the equivalent thermal network model is presented. Then, an improved maximum power point tracking control strategy, based on the power-speed outer control loop, is proposed by shortening the low frequency durations and increasing the speed gradient of the rotor side converter around synchronous speed. Furthermore, combined with the model predictive current control strategy, the switching loss of IGBT modules could be reduced. Finally, the dynamic performances of the junction temperature and power loss of IGBT modules are analyzed through the electrical-thermal model simulation and the equivalent experiment testing. Both simulation and experimental results show that the proposed control strategy could be effective to depress the IGBT junction temperature fluctuation and power loss.