A simple method for self-commissioning of industrial AC motor drives without shaft encoder

The performance of field oriented vector controlled ac motor drives is essentially influenced by the dynamics of the controller loops. Typically in industrial servo drives, standard PI-controllers are used in a cascaded structure. The innermost loop is the current controller loop, whose actual value is given by measurement. This controller is usually adjusted automatically by the knowledge of the electrical motor parameters. The overlying controller loops like speed and position controller require information of the position respectively the derivation of the position. Typically a shaft encoder provides this information but more often a position observer is used instead of. This work presents a method for self-commissioning of speed and position controller for drives without a shaft encoder based on a frequency response measurement of the overall system (mechanics + observer). Experimental results are presented to demonstrate the performance and feasibility of the proposed method.