Fraunhofer Institute for Silicon TechnologyActive front end converter based on MMC
MMC
Modular multilevel converter for hybrid grids.
Design of highly reliable modular multilevel converters
Due to their higher efficiency, improved power quality, inherent fault tolerance and higher density, modular multilevel converters are used in MV and HV applications.
The challenge
Today, power electronic semiconductors and capacitors thermally limit the service life and overload capacity of power electronic converters. Therefore, the temperature peaks of the semiconductors can be reduced by appropriate control, thereby expanding the overcurrent operating range of the modular multilevel converter (MMC) in the headend. However, to achieve this performance, the junction temperature of the semiconductors must be known. That is why we offer measurement techniques to indirectly determine the junction temperature without having to measure it directly.
Our Solution
We offer a measurement technique to indirectly determine the junction temperature of the semiconductors via thermal-electrical sensitivity parameters (TSEP). By connecting the measurement technology to the gate drivers of the MMC cells, the junction temperature can be output as a function of the collector-emitter voltage, for example, and used for overcurrent operation or for self-protection of the power converter.
Yout benefits at a glance
The MMC is a key technology for AC/DC applications in the medium-voltage range. Because this type of topology requires a large number of power electronic devices, it is important to provide a highly reliable converter that ensures uninterrupted operation and reduced maintenance time. Then we offer an MMC with overload capability that uses an independent TSEP for variables other than temperature. Such a solution indirectly monitors the temperature of the semiconductor, which allows management of the overload and extends the life of the converter.