Sensorless Operation of an Inset PM Bearingless Motor Implemented by the Combination Approach of MRAS and HF Signal Injection

On the basis of analyzing the mathematic model of high frequency signal injection and model reference adaptive system, a novel rotor position estimation scheme using the combined rotor position self-sensing method was suggested, which will meet the need of sensorless operation for an inset permanent magnet type bearingless motor. The rotor position detecting principle, such as the saliency-tracking technology with the injection of high-frequency carrier signal at low speed, the observer estimation at high speed, the smooth switching of these two detecting schemes for rotor position estimation and their implementation technique were all discussed in this paper. And then, the sensorless vector control system of an inset permanent magnet type bearingless motor was set up based on the aforementioned position estimation approach. Simulation study demonstrates that the proposed combined self-sensing method is capable of precisely estimating the rotor space position in the full speed regions for the inset permanent magnet type bearingless motor and is capable of achieving stable sensorless suspension operation at the low or high speeds with heavy load disturbance