FIGS. 14A and 14B show simulation results according to the conventional method and the present disclosure when the torque command is changed from ?3.5 pu to 3.5 pu with a 20 pu/s slope and the speed is 150 r/min. FIG. 14A shows the conventional method, and referring to FIG. 14A, if the torque command reaches 1.7 pu, it is impossible to estimate a position. Meanwhile, FIG. 14B is according to the present disclosure, and referring to FIG. 14B, the position is estimated stably in the entire torque range, and the margin of error does not exceed 10°. Thus, according to the present disclosure, sensorless control is possible in the entire torque range.
FIG. 15 shows an experiment result where the torque command to the motor is increased with a slope of 2 pu/s while controlling the speed of the motor constantly at 150 r/min according to an embodiment of the present disclosure.
Referring to FIG. 15, it may be found that the estimated position is significantly different if the torque command reaches 2.3 pu, which is consistent with SISL (signal injection sensorless control) feasibility analysis results.
FIGS. 16A and 16B show experiment results of rotor position estimation according to the conventional technique and the present disclosure.
