Active Thermal Control With Switching Frequency Modulation for Fundamental Frequency Junction Temperature of the VSG

With the widespread utilization of renewable energy sources, the virtual synchronous generator (VSG) with self-synchronization grid-connection capability has received significant attention. As the core component for power conversion, IGBTs have been a focal point of research due to their susceptibility to failure, affecting reliability and lifespan. Existing studies have managed to control internal IGBT chip junction temperature and extend lifespan through appropriate active thermal control (ATC) methods. However, these methods either alter the structure of the original IGBT module or fail to compensate for the degradation in power quality. In addition, they neglect the impact of long-term thermal cycling induced by fundamental frequency current on periodic junction temperature fluctuations. Therefore, this article proposes an ATC method for internal IGBTs in VSG based on switching frequency modulation. This method reduces the average junction temperature of the IGBT and additionally periodic junction temperature fluctuation to some extent. Finally, the proposed method is validated through simulation and experimentation. The experimental results prove the effectiveness of the proposed method.