Abstract
Performances of vector controlled induction motor are improved by knowing the spacial position of the rotating magnetic flux in the induction motor at every instant. Usually. hole generators are buried in the teeth of the stator for detecting the air gap flux. However, this method is strongly affected with the slot ripple and does not work well due to the high temperature operating condition.
This paper proposes a novel and effective method for detecting the magnetic flux. Zero magnetic field sensor(MFS) is applied, which is buried in the yoke of the stator, since it has a wide operating temperature range (-76_??_300°C) with the high accuracy of 0.1%. Two components, radial component and tangential one, are investigated for which is more fit for the purpose. Both of them include no slot ripple but their wave distortion is inevitable owing to the nonlinearity of the core. Inadition, the value of the detected flux also varies as a function of the mounted position of MFS. Their degree is much smaller in the tangential component than that in the radial one. This signifies that the tangential component is profitable for our purpose. The effect of the wave distortion can be almost completely suppressed by properly arranging three MFSs based on the three phase theory without using any filters. DC flux at zero frequency can also be detected. Effectiveness of the proposed method is verified through these experimental investigation.
