Owing to their higher efficiency, improved power quality, inherent fault-tolerance, and enhanced density, multi-level modular converters expand to MV- and HV- power conversion stations, replacing legacy 2-level inverters.
Today power electronic semiconductors and capacitors thermally limit the lifetime and overload capability of power electronic converters. Due to that, the temperature peaks of the semiconductors can be reduced using an appropriate control, which extends the overcurrent operating range of the modular multi-level converter (MMC) in the head-end station. However, the junction temperature of the semiconductors must be known to achieve this performance. That is why we offer measurement technologies to determine the junction temperature indirectly, avoiding the challenge of measuring it directly.
The MMC is a key technology for medium-voltage AC/DC applications. Since this kind of topology requires a high number of power electronic devices, it is important to provide a highly reliable converter ensuring uninterrupted operation and reduced maintenance time. Then, we provide an MMC with overload capability using an independent TSEP on other variables outside of temperature. Such solution indirectly monitors the temperature of the semiconductor, which allows the management of overload and extends a lifetime of converter.
Fraunhofer Institute for Silicon Technology