A transient model of interior permanent magnet machines under stator winding inter-turn short circuit faults

Shen Zhang, Thomas G. Habetler

Abstract: For the widely-adopted inverter-fed drives, the stator winding insulation is more prone to various stresses compared to the line-start machines, i.e. the high rates of voltage change due to inverter switching (dv/dt), which will result in higher chances of insulation breakdown. To better illustrate the dynamic behaviors of the IPM machines under the stator turn fault, this paper presents a transient model of the in the dq <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sup> rotor reference frame where most control algorithms are designed upon, instead of the traditional modeling work commonly adopted in the abc reference frame. In addition, a state-space representation of the dynamic equations is provided by considering the shifts of the three-phase line-to-neutral voltages. Finally, a simplified form of the proposed model in the early-stage turn fault period is proposed and various machine characteristics are illustrated in detail with different severities of the stator turn fault. This model is beneficial for investigating the machine characteristics under various motor control algorithms as the turn fault propagates to the neighboring turns and eventually turn into a complete line-to-ground fault.