PURPOSE: To dissolve the follow-up delay of a digital PLL circuit by providing a feed control apparatus with pulse signal generating and outputting means wherein a pulse signal has a phase synchronous with an AC signal, control means for making the pulse width of a load control signal variable and means for correcting the pulse signal when a signal inputted from outside is judged to be deviated from a set frequency region.

CONSTITUTION: A feed control apparatus comprises a digital PLL circuit system, an output correcting system and a control system. A CPU 20 compares an input angle frequency detected by the digital PLL circuit system with upper and lower limit values and, when the input angle frequency is judged to exceed the limit values, calculates the correcting quantity of the input angle frequency to output the quantity to a frequency integrating circuit 21. The frequency integrating circuit 21 detects a phase correcting quantity, adds the phase counting quantity of a phase counter 14 and the phase correcting quantity to each other and outputs a corrected value. Thus, the follow-up delay of the digital PLL circuit relative to a change in an input signal can be dissolved.