A SVM based four-level open-end winding-induction motor drive with voltage balancing of DC-link capacitors using SVM based HCC front-end converter

A four-level open-end winding induction motor drive can be obtained by feeding an induction motor with open-end windings with two two-level inverters, operating with unequal DC-input voltages, which are in the ratio 2:1. A total of 64 space vector combinations, distributed over 37 space vector locations are rendered by this drive. With the conventional 2-level, 3-ph, VSI, the hexagonal space vector area is divided into 6 sectors only. The same area is divided into 54 sectors with a 4-level inverter, facilitating a better resolution for the synthesis of the reference voltage vector. In this paper, a space vector Pulse Width Modulation (SVPWM) scheme is proposed, which uses only the instantaneous phase reference voltages, obviating the necessity for sector identification and look up tables. Also, this PWM strategy automatically ensures that the inverter, operating with a higher DC-link voltage is switched with a lower frequency. Some of the vector combinations produced by this power circuit configuration overcharge the DC-link capacitor of the inverter operating with lower voltage. This paper describes as to how such an overcharging could be avoided by using a SVM based Hysteresis current controlled Front End Converter (FEC) instead of the conventional 6-diode bridge rectifier.