Improved torque and efficiency of a four switch three phase inverter fed induction motor drive

In this paper, an improved flux weakening control scheme for Four Switch Three Phase Inverter (FSTPI) to produce maximum torque and achieve high motor efficiency in the high-speed region is proposed. In the proposed scheme, a method to generate the optimal flux reference for an FSTPI to enable maximum torque production in the high-speed region is explained in detail. The slip frequency reference is also improved by proposing a method to calculate the optimal rotor time constant. The feasibility of the proposed method is verified by simulation and validated by experimental results which show that the maximum attainable torque and motor efficiency increased in the high-speed region.