Sensorless Harmonic Estimation for Servo Drive with Vibration Load

This paper proposes a sensorless vibration frequency estimation for a servo control system driven by a permanent magnet (PM) synchronous machine. Traditional vibration estimation relies on the measurement using external sensors. A separated accelerometer is installed in the servo system to obtain the vibration harmonic information. Because the accelerometer must be attached on the visibly vibrational location inside the system, this vibration detection results in both installation and reliability issues. Instead of accelerometer, this paper proposes a disturbance observer to estimate the vibration harmonic using machine drive available current and position signal. A real-time signal process is developed to identify the vibration frequency from estimated harmonic. A servo system with a 400W PM machine drive is built to verify the proposed vibration frequency estimation. This paper includes the comparatively evaluation between the accelerometer-based harmonic measurement and the sensorless harmonic estimation.