Model based closed loop control scheme for compensation of harmonic currents in PM-synchronous machines

With increasing use of concentrated windings in permanent magnet synchronous machines harmonic effects have to be considered more and more for current control design. A structural expansion of the control scheme is needed to handle these higher harmonics. In this paper an effective method is proposed to carry out an expansion of the control scheme. Firstly the nonlinear disturbances are transformed into new fictitious rotating coordinate systems to get an easier description of the disturbances. The compensation of the harmonics is achieved in the new coordinates by applying closed loop controllers with suitable disturbance models. Therefore the control scheme is robust concerning parameter variations. In order to decouple reference and disturbance response a nonlinear model based dynamic feed forward control is used. The proposed control scheme is proven by test bench measurements.