Optimal rotor flux regulation for fast-accelerating induction machines in the field-weakening region

Quality and reliability of field-oriented controlled induction machines depend strongly on the capability of the inverter switching strategy to control the current space phasor according to the desired torque value. Especially at high speed, when DC-link voltage is fully utilized, the rotor flux level has to be chosen carefully to enable sufficient dynamic capability of the drive. This paper presents optimal speed- and load-dependent amplitudes of the rotor flux to achieve constant dynamic behavior. A combination of an adaptive machine model with a rotor flux controller maintains excellent flux management, especially during rapid acceleration in the field-weakening area. The advantageous function of the scheme is illustrated by experimental results.