| 摘要 |
PROBLEM TO BE SOLVED: To drive a motor within the range of a thermal limit value for the motor by a method wherein a control circuit is provided with a state observation device which computes an estimated acceleration torque value for the motor so as to be output and with a limit computing unit which limits the maximum value of a speed set value on the basis of a value in which the estimated acceleration value is multipled by a prescribed proportional gain. SOLUTION: A state observation device 22 comprises an adder 24 which adds the difference between a motor torque found by multiplying an armature current detection value by a gain corresponding to a field magnetic flux and an integrating and computing element 26 which integrates and computes the output of the adder 24, and the output of the adder 24 is output as an estimated acceleration torque value τ(tau)a. In a limit computing unit 21, a value in which the estimated acceleration torque τ(tau) a is multiplied by a proportional gain is used as the maximum value of a speed set value, the maximum value of the speed set value by the output of the acceleration computing unit 12 is limited, and the closed-loop control operation of a motor speed is performed as the speed set value at the maximum value or lower. As a result, an industrial machine as a load 3 can be driven within a range which does not exceed the thermal limit value of a motor 2. |
