Experimental Studies on a Novel Braking System for Induction Motors

The results are presented of an experimental investigation of a novel multistage braking method (already reported by the authors in an earlier paper), which employs a graded capacitor system using single phase self-excitation followed by magnetic braking and a small dc injection at the end. Certain experimental observations have enabled a significant simplification of the control circuitry over the earlier reported one. A series of experiments were performed on a laboratory setup to determine the various transients during braking, in order to assess the suitability of the windings and the capacitor system. The effects of the capacitor value on the initial rate of fall in speed, the braking time, and the peak transients of voltages and currents were studied. Braking performance under this scheme is compared with that under the normal dc injection method. Typical experimental recordings are presented. Finally, certain useful experimental criteria for choosing suitable values of capacitors and the time delays between successive stages of switching are discussed.