M.Ing. / Variable liquid resistors are utilised in the rotor circuit, to control mine winders using slipring induction machines. These liquid resistors have a number of disadvantages, therefore a new drive technology is required to replace liquid controllers. A number of machine drives are discussed and a comparative study is made. A 22kW resistively loaded buck chopper in the rotor, is used as a case study. Full design details and procedures are given for the chopper. These designs are verified by simulations and experimental results. A current control was designed and implemented for the buck chopper in the rotor, using a PI controller and pulse width modulation. The 22kW resistively loaded buck chopper operated exceptionally well and it is evident that it could be a viable method for replacing liquid controllers. The oscillation generated in the hoist cables are discussed and a possible counter acting acceleration method of removing these oscillations is described. A rotating oscillation system was designed and constructed for experimental purposes. From the tests undertaken on the experimental system, it was evident that by the implementation of the counter action process, it is possible to remove the oscillations in the hoist ropes.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:3265 |
| Date | 27 August 2012 |
| Creators | Kane, Ian Jack |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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