HF test current injection based self-sensing control of PMSM for low and zero speed range using Two-Degree-of-Freedom current control

This paper deals with an innovative self-sensing control scheme based on test current instead of voltage injection. Using Two-Degree-of-Freedom current control one can overcome the bandwidth limitations which made test current injection unattractive during the last 20 years. The Two-Degree-of-Freedom control scheme consists of a model based dynamic feed forward control to set the reference response and model reference tracking controllers providing disturbance rejection and the position error signals for self-sensing control. Since Two-Degree-of-Freedom control is a model based control scheme the compensation for secondary saliencies is inherently included in the pre-control. It is shown analytically that in case of test current instead of voltage injection just the precise knowledge of the current and position dependent inductance m_qd^HF is needed in case of inductance saliency based sensorless control. The effectiveness of the proposed method is proven by experimental results.