A quantitative evaluation of the efficiency and economic benefits of the Active-Reactive Induction Machine drive in high power applications

In the present scenario, high power industrial drive applications mostly employ Voltage Source Inverter (VSI) fed induction motors. In the very high power ranges (>10 MW), Load Commutated Inverter (LCI) fed synchronous motors are also used. Economy and efficiency are crucial factors for drives in such high power applications. Recently, a new hybrid drive topology using a specially designed dual stator winding induction machine fed from an LCI and a VSI has been proposed. The machine has been named as the Active-Reactive Induction Machine (ARIM). The use of a thyristor-based LCI to handle all the active power, is expected to make the ARIM drive a much more efficient and economic option than the VSI based drives. This paper presents a quantitative evaluation of the efficiency and economic benefits of the ARIM topology employed in a 1 MW drive application, as compared to three other popular drive topologies used in this power range. These are: (a) A low voltage VSI based drive, (b) A medium voltage two level VSI based drive, and (c) A medium voltage three level VSI fed drive. The losses and efficiency in each case are compared by simulation studies using MATLAB/PLECS. Further, an estimate of the approximate costs of the drive topologies is made to compare their economic benefits. It is found that the ARIM drive has major benefits in cost and efficiency, when compared to other conventional drives.