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This paper proposes a new three-phase to five-phase transformer, with a 30-pulse AC–DC converter for power quality improvement in vector-controlled induction motor drive. Here, three isolated transformers (T1, T2, and T3) are used and each transformer is designed to convert three-phase AC-supply into five-phase AC supply, to achieve ten-pulse AC–DC conversion. A unique configuration and angle among these three transformers is designed in such a way that the resultant input current of this transformer shows 30 pulses in it. A hybrid multilevel inverter is proposed in this paper, which is cascading a three-level neutral point clamped inverter with a two-level voltage source inverter to drive an induction motor (IM). A modified level shifted carrier-based sinusoidal pulsewidth modulation and a 3rd harmonic injection techniques are utilized to modify the modulating signal, to enhance the fundamental magnitude, and to reduce the harmonics than traditional technique. The responses of proposed medium voltage induction motor drive (MVIMD) are evaluated by simulating in MATLAB-Simulink. The proposed MVIMD performance is then verified using a scaled down laboratory prototype under various operating conditions such as steady state, starting, load perturbation, speed control, field weakening, varying load conditions, and over a wide speed range of IM. [ABSTRACT FROM AUTHOR]

In this paper, a static synchronous compensator (STATCOM) is proposed in which a new modular structure with conventional three-phase voltage source inverters is used to multilevel operation. The inverters are connected to a transformer in an open-end winding configuration and with three independent DC links. In this structure, the inverters will be connected in a cascade configuration. Besides the multilevel operation, the system is also characterized by low required blocking voltages for switch ratings, since the proposed STATCOM can apply the double of the DC capacitor voltage to the transformer windings. The development of the control system for the proposed topology is also presented. The operation of the proposed topology and the performance of the developed control system will be tested through several simulation and experimental tests. [ABSTRACT FROM AUTHOR]