Experimental Identification of the dqθ Flux Maps of Synchronous Machines

This work proposes a test sequence and data processing method for evaluating the complete dq-theta flux maps of a Permanent Magnet Synchronous Machine, including its spatial harmonics. The constant-speed measurement procedure of the fundamental (sinusoidal) flux linkage curves is complemented by the proposed method to extract space harmonic information from the measured voltage and current signals. The average between symmetric motor and generator operations, already adopted for fundamental flux maps to gain immunity from the stator resistance voltage, is extended here to the complete flux maps. In addition, the dq-theta torque map, inclusive of the torque ripple component, can be calculated off-line by manipulation of flux and current quantities, without the need of dedicated torque measurement sessions. The outcomes of the proposed procedure are 3-dimensional flux maps representing the dq flux linkages function of dq currents and the electrical rotor position theta. The results presented in the paper refer to the experimental characterization of a 40 Nm, 11 kW peak PM synchronous machine.