A New Position-Sensorless Position Control Method for High-Speed Spindle Systems

Abstract

This paper proposes a new position-sensorless position control method for high-speed spindle drive systems. Mechanical vulnerability of position-sensors such as encoder mounted on spindle motor is becoming a serious problem as required speed increases. For high-speed more than 1, 500 (rad/s), sensorless drive is preferred. It is possible for current technologies to control spindle motor in speed control mode without the sensor, but not in position control mode without the sensor. In example of high-speed spindle systems of automatic machine tools, implements must be automatically attached on and removed off the spindle at a standstill. The automation means necessity of position control, for which current technologies require the sensor. The proposed method makes it possible to realize pure-sensorless high-speed spindle systems performing in both speed and position control modes. The method can attain position control performance of quick settlement from speed control and repetitive positioning-precision of 0.006 (rad), 0.4 (degree), which is similar to one by current sensor-used methods.