Torque capability improvement of sensorless FOC induction machine in field weakening for propulsion purposes

An electric propulsion system is generally based on torque controlled electric drive and DC series motors are traditionally used for propulsion system. Induction machines, which are reliable, low cost and have less maintenance, satisfy the characteristics of the propulsion and reinstating the DC series motor. Field oriented control (FOC) of induction machines can decouple its torque control from field control which allows the induction motor to act like a separately excited DC motor. In this paper, the characteristic control of induction motor is achieved through appropriate design modification of induction motor by varying magnetizing current to produce maximum torque in field weakening (FW) region. Thus to improve the torque capability of induction machine in FW region by varying machine parameters. The sensorless operation of the induction motor is carried out by adopting model reference adaptive system (MRAS) using sliding mode control (SMC) and a FW algorithm based on the voltage and current constraints. The simulation of the induction motor drive models based on the design options have been carried out and analyzed the simulation results.