Improved torque sharing in multi induction motor VFD systems using current feedback

This paper proposes an improved method for sharing the torques between two rigidly coupled Induction Motors (IMs) that may have different parameters. The Volts-per-Hertz (V/F) control forms a large percentage of variable frequency drives (VFD) used in industry. The torque delivered by V/F controlled IMs is highly dependent on the rotor resistance, which may be susceptible to various external factors. As a result, the torque developed by the individual IMs under load may not be properly shared. The proposed methodology is verified and demonstrated experimentally, and is shown to improve the load sharing very effectively under significant variation in machine parameters.