Sensorless Control of Induction Motors for Maximum Steady-State Torque and Fast Dynamics at Field Weakening

A method is described that fully utilizes both the maximum inverter voltage and current for steady-state torque production at field weakening. The control algorithm thus provides the maximum possible torque in the entire field weakening region. Dynamic requirements when operating at maximum voltage are met by creating a temporary voltage margin to enable a fast reaction of the current controller. The control algorithm is insensitive to changes of the machine parameters and to variations of the dc link voltage. The approach is based on a stator flux oriented scheme and permits operation without using a speed sensor