Wide bandgap based modular driving techniques for switched reluctance motor drives

In switched reluctance motors, the stator can be seen as comprising a stator yoke and a modular tooth-coil construction. Each module consists of a concentrated winding wound around a steel pole. In the conventional driving technique, depending on the number of the stator poles, a number of coils are connected together and driven from one asymmetric H-bridge. Another possible driving technique is the modular one in which each stator coil is driven by a separate asymmetric H-bridge. In this way, the fault tolerance of the drive is highly enhanced. In this paper, three modular driving techniques are proposed, simulated and compared to the conventional one. The difference between the three modular techniques is in the number of turns per stator coil and the DC-link voltage compared to the conventional one. The first technique maintains both the number of turns per coil and the DC-link voltage, the second one maintains the number of turns per coil while halving the DC- link voltage and the last one maintains the DC-link voltage and doubles the number of turns per coil. All the techniques are applied on a 6/4 SRM machine. The technique that maintains the DC-link voltage and doubles the number of turns shows superior performance in terms of the drive efficiency and the converter power density but results in the highest torque ripple. The technique that halves the DC-link voltage achieves a low torque ripple and an efficiency equal to the conventional technique. The converter is designed using SiC technology to enable higher switching frequency capability so that, a smaller DC-link capacitance can be obtained and a high drive efficiency as well