Four-Quadrant Speed Control Circuit of DC Servo Motor using Integrated Voltage Control Method.

Abstract

A DC chopper using an Integrated Voltage Control Method is stable and has no steady state error. A DC chopper using this Integrated Voltage Control Method can be used to extend the DC chopper into a Two- or Four-Quadrant DC chopper easily. A Two- or Four-Quadrant DC chopper utilizing this method has many good characteristics, for example a very simple control circuit, very rapid response and automatic changing of active quadrant without a current feedback loop.Applying this Integrated Voltage Control Method, we constructed a speed control circuit for a DC servo motor drive. This circuit has two feedback loops: the first one is a DC motor speed feedback loop and the second is a DC chopper output voltage feedback loop which is eliminated DC component by a coupling capacitor. This speed control circuit utilizing an Integrated Voltage Control Method is stable and has no steady state error, either. And we can determine a damping factor of this speed control system freely if the DC servo motor is over damping.We investigated the effect of the coupling capacitor in the voltage feedback loop on chopping frequency. If the chopping period becomes large, the speed ripple of DC servo motor becomes large. We found that the coupling capacitor has little effect on the chopping frequency for usual DC servo motor. This speed control circuit utilizing an Integrated Voltage Control Method ensures that the ripple speed of the DC servo motor remains at a low level.