Brushless DC motor actuator health monitoring and degradation compensation via real-time multiple parameter estimation

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Variations of the motor parameters, which can be classified as slowly developing faults due to environmental factors, temperature, build variations, aging, etc. directly impart inaccuracies in the inverse motor model and thus the performance of the system suffers. A multiparameter estimation is proposed in this paper and stability of the scheme is mathematically proved. Two methods to improve the dynamic performance of the estimator are proposed. The first method approximates the motor electrical dynamics using the state transition matrix in the motor inverse model. It improves the torque tracking; consequently the current error reflects more of the parameter discrepancy. The second method approximately compensates the motor speed sampling delay error. Comparison of simulations for closed-torque-loop voltage control of an electric power steering system actuator confirms a lower bound of error of the estimated parameter and faster adaptation with the proposed improvements for the estimation scheme. © 2007 Inderscience Enterprises Ltd.

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International Journal of Automation and Control