engleski

Design and Implementation of the Extended Kalman Filter for the Speed and Rotor Position Estimation of Brushless DC Motor

A method for speed and rotor position estimation of a brushless DC motor (BLDCM) is presented in this paper. An extended Kalman filter (EKF) is employed to estimate the motor state variables by only using measurements of the stator line voltages and currents. When applying EKF it was necessary to solve out some specific problems related to the voltage and current waveforms of brushless dc motor. During the estimation procedure the voltage and current measuring signals are not filtered, which is otherwise usually done when applying similar methods. The voltage average value during the sampling interval is obtained by combining measurements and calculations, owing to the application of the predictive current controller which is based on the mathematical model of motor. Two variants of the estimation algorithm are considered: (1) speed and rotor position are estimated with constant motor parameters and (2) the stator resistance is estimated simultaneously with motor state variables. In order to verify the estimation results the laboratory setup has been constructed using motor with ratings 1.5 kW, 2000 rpm, fed by IGBT inverter. The speed and current controls, as well as the estimation algorithm, have been implemented by digital signal processor TMS320C50. The experimental results show that is possible to estimate the speed and rotor position of the BLDCM with sufficient accuracy in both the steady state and dynamic operation. Introducing the estimation of the stator resistance the speed estimation accuracy is increased, particularly at low speeds. At the end of the paper, the characteristics of the sensorless drive are analyzed. A sensorless speed control system has been achieved with maximum steady state error between reference and actual motor speed of ą1% at speeds above 5% of the rated value.

brushless DC motor; extended Kalman filter; speed and rotor position estimation; predictive current controller; digital signal processor

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