Patent ID: 7141952

Claim:
A method of initiating a start commutation of synchronous servo-drives utilizing two coupled control circuits, the steps of the method comprising: a) providing a current control circuit and an angle control circuit for said two coupled control circuits; b) outputting a field angle α from said angle control circuit; c) outputting a transverse current iQ from said current control circuit, said transverse current iQ derived through a minimized Clarke-Park transformation incorporating two phase currents iU and iV and said field angle α as inputs, thereafter outputting a current vector iM; d) outputting voltages uU, uV and uW by a minimized inverse Clarke-Park transformation incorporating said transverse current iQ and said field angle α as inputs; e) providing an incremental position sensor signal to said angle control circuit; f) inputting a ramp-like current desired value to said current control circuit; g) inputting a constant angle desired value to said angle control circuit; h) controlling said transverse current iQ with said angle control circuit by rotating an electromagnetic field; i) inputting an S-shaped disturbance signal into said angle control circuit; j) providing a shaft for said servo-drive, said shaft mechanically fixed in position during an initialization of said start commutation, and said shaft precisely controlled to a same position as at a beginning following said initialization.