Detection and compensation of torque harmonics in drive with induction motor and gear

In many solutions of drives, the torque transmission systems are used for torque converting from the motor shaft to the load. Properties of torque transmission system are a reason of mechanical vibration occurring in drive system. Analysis of drive vibration, usually measured by the accelerometer, makes it possible to create diagnostic system for detection of mechanical faults of drive. In many applications, an introducing of vibrations to drive system is undesirable. Mechanical vibrations of drive can be reduced by generation of appropriate torque components in electric machine. Proper compensation of mechanical vibration requires information about amplitudes and frequencies of vibration harmonics. In drive system with gear, the reduction of mechanical vibration and early detection of gear damages require information about mutual position of toothed wheel and the torque transmitted by gear. Analysis of state variables of induction motor makes it possible to indicate the instants of toothed wheels meshing. It makes it possible to eliminate both: vibration and optical sensors in systems of detection of gear damages and compensation of mechanical vibration. In this paper a method of sensorless detection of torque ripples, caused by gear transmission, is proposed. Presented method can be use in systems for early detection of gear damages and for active compensation of mechanical vibration. The results of simulation and experimental researches on proposed detection and compensation method are presented in the paper. The experiments were provided for a drive with 10kW induction motor with gear and for a high-speed train drive with gear and 1.2MW asynchronous motor.