Initial position estimation and low speed sensorless control of synchronous motors in consideration of magnetic saturation based on system identification theory

We propose a novel method for estimating the initial position and achieving low-speed sensorless control of synchronous motors based on system identification theory. We derive mathematical models that consider magnetic saturation, and use this model for position estimation. The proposed method requires neither any band-pass filters nor motor parameters, and it can be applied to all kinds of synchronous motors without any tuning. Polarity detection of the magnetic pole can be also determined simultaneously with position estimation, making extra signals for polarity detection unnecessary. The proposed estimation method is verified experimentally.