Cogging Torque
The cogging torque of the generator was measured at zero excitation to determine cogging characteristics. The generator was rotated at low rpm (about 3-rpm) to measure the dynamic characteristics, acquired through a high speed data acquisition system. This measurement was compared to another measurement of cogging taken by hand spinning the rotor while the torque was recorded. The dc offset about was 0.2Nm. The cogging torque characteristic is presented below in Figure 9. The rotor was not held in position, therefore the plot references measured data points rather than rotor position.