Patent ID: 7642740

Claim:
A servomotor controller, comprising: a bus voltage detecting means for measuring a bus voltage converted from an AC power supply voltage into a DC voltage by rectifying and smoothing the AC voltage, to output a bus voltage signal; a current detecting means for detecting current passing through a servomotor, to output a current value signal; a control means for switching, depending on the bus voltage from the bus voltage signal, a position control operation with a velocity control operation, to output a control signal, in order to decrease the current supplied to the servomotor in a case where the bus voltage is lower than a first predefined reference voltage, by referring to a shaft position signal of the motor, which is information on the shaft position of the servomotor and outputted from an encoder provided for the servomotor, a position command, the bus voltage signal, and the current value signal; a drive control means for outputting a drive voltage based on the control signal; and a motor drive circuit for outputting predefined current to the servomotor based on the bus voltage and the drive voltage inputted from the drive control means.