Single Source Floating Capacitor Fed Multi-Level Open-End Winding Induction Motor Drive with Extended Linear Modulation Range and Minimum Number of Switches

This paper presents a strategy to increase the linear modulation range (LMR) of a cascade 2-level inverter in the maximal distention mode (MDM). A conventional 2-level inverter with a DC source is connected to one end of the open-end winding induction machine (OEWIM). The other end of the machine is connected to another 2-level inverter with a floating capacitor, whose voltage is controlled at 0.5 V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</inf> in order to attain maximal distention. Maximal distention mode accounts for low voltage stress and improves power quality as it has largest number of effective pole voltages in this mode. In maximal distention mode the DC link voltage could not be used appropriately due to charge balance issue of the floating capacitor. The proposed modulation strategy achieves almost 39 % increase in the DC link utilisation compared to existing techniques with the lowest number of switches and single DC source, while maintaining the floating capacitor voltage at the desired level which is a significant achievement. The proposed scheme is simulated on a 4 kW, 415 V, 50 Hz Induction Motor, using MATLAB Simulink with PLECS (Piecewise Linear Electrical Circuit Simulation) and found to be satisfactory.