In a switched reluctance (SR) drive, the transfer of the de-fluxing energy in stator windings back to the dc-link results in a large dc-link capacitance. This limits its applications where weight and size of the drive are restricted. This thesis describes a control technique for the dc-link capacitance minimisation in an SR drive. The proposed control technique maintains the constant power transfer between the de supply and the H-bridge converter. The average dc-link current over a switching period is kept constant. When the output of the integrator, i.e., the average dc-link current, reaches a predefined value proportional to the torque demand, appropriate switching takes place. This is achieved by integrating the dc-link current in each switching period. This technique is called dc-link current integration control (DLCIC). The de-fluxing current from the outgoing phase is not fed back to the dc-link capacitor. Instead, it is transferred to the incoming phase to prevent a negative dc-link current, which causes a fluctuation in the capacitor voltage. Extensive simulation studies of the DLCIC and other techniques reported in literature have been performed and the simulation results from DLCIC are compared with those from other techniques such as Hysteresis Current Control (HCC) and Pulse Width Modulation Current Control (PWMCC). It has been shown that the peak-to-peak voltages across the dc-link capacitor from DLCIC are the lowest amongst other techniques. The operational speed range of the DLCIC is determined and the optimal turn-on and turn-off angles are proposed. Filter components under the DLCIC operation has been designed and compared with the filter for HCC. It is shown that the weight of the filter for DLCIC is far lower than that for HCC. The proposed control technique have been validated by experiments. The experimental results show that at the dc-link voltage ripple which results from DLCIC is much lower than that from HCC. This demonstrates that DLCIC can minimise the dc-link capacitance in an SR machine drive.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:578057 |
| Date | January 2013 |
| Creators | Suppharangsan, Wisaruda |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/14610/ |
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