Control Performance Analysis and Improvement of a Modular Power Converter for Three-Phase SRM With Y-Connected Windings and Neutral Line

In this paper, the control performances of a modular power converter for a three-phase switched reluctance machine (SRM) are analyzed and improved. The converter is implemented by a dual and a six-pack IGBT module, and the phase windings of the SRM are Y-connected and bipolar excited. The performances of the existing control method for this converter are evaluated by simulation and compared with those for the traditional asymmetric half-bridge converter, and the drawbacks, such as big torque ripple and small average torque, are presented. With the new operating modes of phase branch, namely magnetization, freewheeling, and demagnetization, improved basic control methods are proposed, which can effectively enhance the performances, flexibility, and applicability of the converter. Furthermore, the direct instantaneous torque control, which can reduce the torque ripple, is realized with the converter as well. Several simulations and experiments under different working conditions are carried out to verify the performances of the improved control methods.