Mutual coupling and its effect on torque waveform of even number phase switched reluctance motor

Switched reluctance motors are often running in status of two phases excited simultaneously. Mutual coupling has effects on not only the flux distribution and magnetic saturation, but also the ability of torque output. The two adjacent phases of switched reluctance motor can be excited in two modes, the long-flux-path mode and short-flux-path mode. The calculation method of mutual inductance in two-phase excitation mode is given. The change law of mutual inductance against rotor position and phase current is presented. The influence of mutual coupling on average torque is theoretically derived. For a 4-phase 8/6 switched reluctance motor, the irregular characteristics of transient torque waveform are analyzed under two types winding connection using finite element method. Based on the mutual inductance, an approach that changes the control parameters of asymmetrical phases is proposed. The simulation result shows that the minimum and average torque are both increased, the torque ripple is reduced and the torque wave becomes regular.