Design of an Improved Stator Flux Observer Based on a Super-twisting Algorithm

For the direct torque control system of six-phase induction motor-oriented on the stator flux, it is very important to accurately observe the stator flux. The most commonly used stator flux observation method is the traditional U-I observation method, but considering that the pure integral link used will be affected by DC bias at low speed, the gap between the observed flux and the actual flux will become larger and larger, which will affect the control effect of the system. In this paper, an improved stator flux observer based on Super-twisting with the amplitude limiting integrator was proposed. On the one hand, it has a strong observation accuracy and on the other hand its adaptability is also strong, and this could effectively overcome the problem that the lower flux observation precision caused by DC bias at low speed of the motor. Finally, the correctness of the improved stator flux observer is verified by simulation.