JPH0581426B

PURPOSE:To constitute optimum speed command system at all times by a method wherein arbitrary relationship of master motor and slave motors is set among motors and ratio control actions of respective motors are made possible in the set relationship of master motor and slave motors. CONSTITUTION:When individual control action mode is set by a mode changing-over means 104, a control means 106 outputs rotational frequency signals sent from a rotational frequency setting means 101 to a speed command signals to respective motors 100. And when mode is changed-over to ratio control action mode, the control means 106 calculates the rotational frequency ratio among the respective motors 100 on the basis of the measured rotational frequency signals of the respective motors sent from the rotational frequency setting means 101 or of the speed command signals, which are sent from the speed commanding means 107 to the respective motors. On the master motor and slave motors 100, the relationship among which is set by a setting means 103 of the relationship of the master motor and slave motors, the control means 106 calculates the rotational frequency of the master motor through the speed setting done at a line speed setting means 105 and then calculates the rotational frequency of the slave motor on the basis of the rotational frequency of the master motor and the rotational frequency ratio and outputs them to a speed commanding means 107, which outputs speed command signals to the master motor and slave motors 100.