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This paper presents the real-time implementation of a novel wavelet-based multiresolution proportional-integral-derivative (PID) controller for the accurate speed control of the interior permanent-magnet (IPM) synchronous motor drives under system uncertainties. In the proposed wavelet-based PID controller, the discrete wavelet transform is used to decompose the error between actual and command speeds into different frequency components at various scales. The wavelet-transformed coefficients of different scales, which represent many underlying phenomena such as process dynamics, measurement noise, and effects of external disturbances, are scaled by their respective gains and, then, are added together to generate the control signal. The performance of this newly devised wavelet controller is evaluated in both simulation and experiments. The complete vector control scheme incorporating the proposed wavelet controller is successfully implemented in real time using the ds1102 digital signal processor board for the laboratory 1-hp IPM motor. In order to prove the superiority of the proposed controller over conventional controllers, a comparison between the proposed and fixed-gain controller-based systems is made at different dynamic operating conditions.
Date of Publication: Nov.-dec. 2008