Stability Enhancement of Compensated V/f Induction Motor Drive Using Active Damping

초록

Compensated volts per hertz (V/f) control can cause instability in induction motors due to the interaction between electrical and mechanical subsystems, depending on motor parameters and operating conditions. This paper shows that voltage and slip compensation, while improving steady-state performance, further widens the unstable operating region compared to constant V/f control. To address this, an active damping strategy combining q-axis voltage damping and frequency damping is proposed to enhance system stability. The voltage damping actively mitigates disturbance voltages arising from imperfect decoupling, while the frequency damping provides virtual resistance through slip frequency modulation. An augmented small-signal model combining low-pass filter dynamics is developed to analyze closed-loop stability. Simulation results validate the predicted stability boundaries, and experimental results on a 5.5 kW induction motor confirm successful oscillation suppression at 20 Hz and stable operation under load disturbances.

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