Poly-phased Matrix Converter — A 27 input phases to 3 output phases experimental set-up running with hard and soft commutations

This paper presents an experimental set-up of a 27 phases input to 3 phases output Poly-Phased Matrix Converter (27×3 PPMC) realised for the real time experimentation of the dedicated control electronics. When the original converter system is dedicated to the frequency conversion from a fast rotating generator directly coupled to the gas turbine for feeding into the 50 Hz grid with a power level up to the 100 MW range, the power level of the experimental set-up is chosen at about 1 kW. First experimentations are documented with a frequency adaptation from 100Hz to 50Hz. The poly-phased synchronous machine´s induced voltages are emulated with 27 linear power operational amplifiers, feeding the primary winding of small transformers. The secondary windings built the polygonal connection of the stator of the machine, and are connected to the 27 inputs of the poly-phased matrix. The PPMC is run in mix mode operation, which is a mix of natural and forced commutations. This paper also presents the theory that goes along with the mix mode operation of the PPMC and investigates especially the losses in the RC snubber circuits.