Vinay Kumar1, Sanjiv Kumar2 and Seema Paroha1
1National Sugar Institute, Kanpur, India; vinay_ind@yahoo.com
2Department of Electrical Engineering, Harcourt Butler Technical University, Kanpur, India
An improved electric drive is presented for coupled motor-run sugarcane preparation machines in the sugar industry. The conventional slip ring induction motor (SRIM) drive has shortcomings of huge slip power loss, high drop in the rated speed, less flexibility for realizing optimum knife/hammer tip speed, low power factor, and unequal load sharing. The recently introduced, two-level inverter-based variable frequency drive (VFD), though it has addressed the issues with the conventional SRIM drive, has drawbacks of high total harmonic distortion (THD) in the input current and the inverter output voltage, high dV/dt stress on the inverter switches and high common mode voltage (CMV). A performance review of the existing electric drives is presented, and then the proposed three-level inverter-fed induction motor drive with an 18-pulse rectifier is presented as an improvement over the existing ones.