State-Complementary Switching Pattern-Based Modulation for Current-Ripple Reduction in SRM Drives Using Double-Updating Scheme

The modulating logic in the existing switching pattern can result in an apparent current ripple in SRM drives and restricts the generation of freely available voltage outputs within a carrier cycle. To address the problem, this article proposed a modulation technique based on a state-complementary switching pattern. First, the studied switching pattern is capable of producing the complementary state of two fully full-controlled switches at both the beginning and end of each half-carrier cycle. This enables the production of zero voltage in the state-complementary state, allowing for two isolated nonzero voltages to be generated within a carrier cycle. Based on the feature of nonzero-voltage output, a corresponding modulation logic is designed to minimize the current ripple caused by voltage harmonics. By increasing the number of freely generated nonzero voltages from one to two, increased modulating freedom for the dc component facilitates the implementation of a double-updating scheme. In comparison, the studied modulation significantly improves current-control accuracy without requiring changes in inverter topology. Finally, the experimental verification conducted on an 8-kW SRM platform confirms the superiority of the proposed approach.