The Performance Improvement of Constant V/f Control of Induction Motor Drive in Low Speed Range

This paper presents the performance improvement of constant V/f control of induction motor drive. In order to compensate the stator resistance voltage drop at low speeds the steady state equivalent circuit of an induction motor is analyzed to establish the equations of the stator resistance compensation. The magnitude of the stator resistance voltage drop is calculated by vector compensation. This method requires only the stator resistance and the nameplate data of motor. The slip frequency compensation is also proposed to reduce the steady state speed error. The steady state torque equation and a linear torque-speed approximation are simply designed for slip calculation. The simulation and experimental results confirm the effectiveness of the proposed scheme especially in the low speed range