| 摘要 |
PROBLEM TO BE SOLVED: To diagnose an encoder fault without provision of a special speed sensor on a motor.SOLUTION: A current sensor 17 detects a current which flows through a motor 5. An A/D converter 19 performs A/D conversion of an output signal of the current sensor 17 to output a current signal. An encoder 6 detects the rotation of the motor 5 to output an encoder signal. A safety monitoring device 12 acquires a safety signal, the current signal and the encoder signal. The safety monitoring device 12 calculates the speed estimation value of the motor 5 on the basis of the current signal, and calculates the speed measurement value of the motor 5 on the basis of the encoder signal, so as to output a halt signal when a difference between the speed estimation value and the speed measurement value exceeds a predetermined threshold. According to the halt signal, an emergency halt circuit 18 outputs an interception signal to the drive circuit 15 to halt the motor 5.SELECTED DRAWING: Figure 1 |
