Multi-Phase Transformer Configured 20-Pulse AC-DC Converter Fed Cascaded MLI Based Speed Sensorless Vector Controlled IMD

This paper deals with a multi-phase transformer (MPT) based 20-pulse converter used in a 3-level cascaded multilevel inverter (MLI) fed medium voltage induction motor drive (MVIMD). In this work, an MPT is proposed, which is converting 3-Φ AC-supply in to 5-Φ AC-supply. Therefore, it is designed as a 20-pulse converter. Due to this, the presented IMD has acceptable power quality even at very light load condition. At the drive end a 3-level cascaded MLI is utilized, which is cascading two three-phase VSIs. This 3-level inverter does not require any clamping diodes like NPC inverter and free from DC-link capacitor voltages balancing issues. To achieve reduced hardware complexity, size, elimination of the sensor cable and to increase reliability of MVIMD, a speed sensorless vector control is used in this paper. The behavior of the system is examined by simulating it in MATLAB-Simulink, which is also proved by means of test results taken from a laboratory prototype under all required operations of IMD.