Fast Modular Multilevel series/Parallel Converter for direct-drive gas turbines

Abstract

We present a novel Modular Multilevel Parallel Converter (M2PC) technology that solves key issues in the application in frequency-variable direct-drive gas turbine systems with high rotational speed as stationary power supplies as well as in mobile setups on ships, cars, and airplanes. In contrast to conventional converters, the M2PC can operate with fundamental frequencies up to the megahertz range at high efficiency. A high power quality on both generator and load side eliminates the need of additional filtering or of large commutation inductances, reduces the loss in the generator, and diminishes dielectric stress on the insulation in the generator windings. The modularity of the converter enables splitting the overall power rating into small fractions with respect to current and voltage, which can be managed with low-voltage electrolytic capacitors and field-effect transistors. Thus, the technology enables a high power density, scalability by adding or removing otherwise identical submodules in order to change peak voltage and power ratings.