Sensorless Vector Control of Induction Machine Using High Frequency Synchronous Injection

This paper presents the sensorless vector control of an induction machine in which high frequency signal injection is used to estimate the rotor flux vector's actual angle. The signal used for these calculations is injected in the estimated synchronous reference frame, from where comes the method's synchronous attribute. The sensorless vector control is constructed with the most commonly used cascade PI controller structure, both on the flux and the angular speed control paths of the system. This paper focuses the properties of the selected common coordinate system's angle estimation considering the controls structure. The mathematical background of the method will be detailed, along with the PLL's tuning, which is used for the estimation.