In this paper a spindle motor control system for a NC lathe is described with special emphasis on the speed control portion of the system.
This thesis is a part of the project sponsored by Dae Woo Heavy Inc. We have constructed two-axis NC control system with software, hardware part, servo controller and spindle controller.
The basic scheme for the armature and field controller system is described for a wide range (30-3,000 rpm) of spindle speed.
The thyristor phase controlled dual converter is designed as a power amplifier for the DC spindle motor which drives for a given function (CSSC, thread cutting).
The current control loop, a minor loop of the Velocity control system, is designed to limit the steady-state armature current value below a certain level.
With a good care of current limit on occasion of abrupt deceleration of speed the spindle speed control with a wide range (30-3,000 rpm) of speed is accomplished.