An improved current sampling scheme using three resistors for induction motor drives based on current prediction

In order to solve the existing problem of the traditional three-resistor current sampling scheme of an inverter for an induction motor, a predictive current model based on the mathematical equations of an induction motor on the synchronous rotating frame is proposed to reconstruct the phase currents when the zero voltage vector duration is not long enough. The principle of this method is detailed in the paper. Then a simulation model of a vector-controlled induction motor drive that utilizes the proposed current sampling scheme is established in the SIMULINK platform. The simulation results verify the novel current sampling scheme. Additionally, the speed operating region can be broadened and the modulation index(MI) can be increased.