Virtual Current Compensation-Based Quasi-Sinusoidal-Wave Excitation Scheme for Switched Reluctance Motor Drives

In this article, we propose a novel quasi-sinusoidal-wave excitation scheme for switched reluctance motors (SRMs) to minimize torque ripple fully considering the high-order inductance harmonics and their phase angle difference. The torque production mechanism is interpreted by the interaction of phase inductance harmonics and the defined virtual phase currents, based on which the components, influence factors, and compensation principle of torque harmonics are analyzed in detail. To reduce the torque ripple caused by the fundamental and zero-axis virtual currents, this article proposes a
q
-axis virtual current injection strategy based on the specific constraints of the
q
-axis virtual currents in different
dq
0-axis coordinates and a
zero
-axis virtual current optimization strategy based on extreme point determination method, respectively. Meanwhile, an online torque modification is specially applied to the defined disaster regions to minimize the uncontrollable torque error. In addition, a vector resynthesis strategy of fundamental virtual current is adopted to further improve the torque capability by minimizing the generation of negative phase torque. The proposed quasi-sinusoidal-wave excitation scheme shows strong universality and excellent effectiveness for SRM with various structure differences. Experiments on a three-phase 12/8-pole SRM prototype are carried out to verify the feasibility and effectiveness of the proposed scheme.