Improved Speed Sensorless Vector Control Algorithm of Induction Motor Based on Long Cable

In many applications, especially electrical submersible pump required remote operation of inverter via a long motor cable. The conventional control algorithm of induction motor (IM) didn’t operate effectively, which ignored the influence of the cable length, and didn’t consider the effect of long cable distribution parameters. A speed sensor technique was also difficult to achieve. In this paper, an improved speed sensorless vector control algorithm (ISSVCA) for IM based on long cable was proposed. Based on the analysis of long cable motor drive system of the inverter, the two-port π network model of the long cable was established. The functional relationship between the voltage/current parameters of the two ports of the long cable and the cable distribution parameters was deduced. The function expression was transformed to the α − β stationary reference frame, the accurate motor terminal voltage/current was calculated, so that the flux model was constructed to realize the observation of the flux, accurate velocity identification, and closed-loop control of the torque, flux and current. Simulation and experimental results showed that the proposed ISSVCA based on long cable increased the starting electromagnetic torque, decreased speed dip and speed recovery time caused by sudden loads, reduced the DC current harmonics, and had good dynamic and static characteristics.