High ripple torque is the main causes of vibration in induction motor that lead to backlash. It is the distance through which any part of a machine system may move in one direction without applying enough force to the next part in mechanical sequence and is a mechanical form of dead band. It can cause positioning error on a hole location, if the motion required to create a holes lead to a reversal in axis direction, it also causes loss of motion between reducer front as well as back shafts, making it difficult to achieve accurate part in machine equipment.
It further lead to the production of less standard products of machine equipment etc.
The experiment was carried out to determine the error that causes the backlash using torque ripple test apparatus. The motor with ripple torque of 0.9Nm was linked to the shaft of the motor and with a load torque sensor that can measure the vibration and equally give the vibrational result of the motor. The DC voltage was supplied to the motor and observed a peak to peak torque equal to 0.9Nm, and 0.15Nm. The flux leakage error was also determined using flux meter to measure the coils in the slots of the stator of the induction motor and also the different poles of the motor was measured to determine the position the stator flux linkage of the space vector.
The errors were simulated in Simulink environment using director torque control and fuzzy logic with duty ratio control. The torque error of 0.15Nm were reduced to 0.05 and fuzzy logic duty ratio reduce it further to 0.0055Nm The use of the duty ratio control resulted in improved steady state torque response with less torque ripple than the conventional DTC. Fuzzy logic control was used to implement the duty ratio controller. The effectiveness of the duty ratio method was verified by simulation using MATLAB/SIMULINK.
After the implementation, we observed that the ripple was reduced drastically and we are able to achieve 95% of improvement.