Improved performance of sensorless induction motor drive based on variable link voltage

Most sensorless algorithms are based on the mathematical modeling of motors, and all the information is obtained from the monitored voltages and currents. Therefore, the accuracy of such variables largely affects the performance of a sensorless induction motor drive. However, the output voltage of the SVPWM-VSI which is widely used in a sensorless induction motor drive has a considerable error, especially in a low speed range. This paper proposes a variation of the dc link voltage as a high-performance strategy for overcoming the above problem. The proposed strategy leads to an improved resolution of the output voltage of the SVPWM-VSI in a sensorless induction motor drive. Simulation and experiment have been performed for the verification of the proposed strategy.