Stabilization Method Using Equivalent Resistance Gain Based on V/f Control for IPMSM with Long Electrical Time Constant

This paper proposes a novel feedback control loop based on a damping control in a V/f control in order to stabilize interior permanent magnet synchronous motors (IPMSMs) with a long electrical time constant. A problem of the conventional damping control is that ignored roots move to the unstable region due to the conventional damping gain K 1 . In addition, the ignored roots are apt to become unstable because of its long electrical time constant. Therefore, a novel method is proposed in order to solve this instability problem. In this paper, first, a boundary condition of stable region is derived based on state equation. Then, a novel current feedback loop of the current is added to an output voltage command. As experimental results, the motor becomes unstable with the conventional damping control under a rated speed of 0.9p.u. and a rated torque of 0.7p.u. Under the common operation condition, the motor is stabilized by employing the novel feedback control loop.