On Stability of Open-Loop Operation without Rotor Information for Brushless DC Motors

Abstract

Open-loop operation mode is often used to control the Brushless DC Motors (BLDCMs) without rotor position sensors when the back electromotive force (EMF) is too weak due to the very low rotor velocity. The rotor position information is not necessary in this mode and the stator windings are supplied with voltages under a certain ratio of the amplitude to the frequency. However, the rotor synchronization will be destroyed once if the commutation instant is inappropriate. In order to improve the reliability of the open-loop operation mode, a dynamic equation is established to represent the synchronization error between the rotor and the stator. Thereafter, the stability of the open-loop control mode is analyzed by using Lyapunov indirect method. Theoretical analysis indicates that the open-loop control mode is asymptotically stable only when the commutation instant of the stator current lags behind the ideal one suitably. Finally, theoretical analysis is verified through the experimental results of a certain BLDCM.

Indirect Measurement of Rotor Dynamic Imbalance for Control Moment Gyroscopes via Gimbal Disturbance Observer

“…Assume that PMSM has a surface-mounted permanent magnet rotor, 3–phase wye-connected symmetric stator windings, and ideal back EMF of sinusoidal waveform, and then the electromagnetic torque can be written without consideration of salient and slot effects, magnetic saturation, and losses due to hysteresis and eddy current, as follows: where i a , i b , and i c are three-phase stator currents; K T and θ e denote the torque constant and the electrical angle of the motor respectively [ 30 ].…”

Design and tuning of pid algorithm for optimum performance of pvtol system

“…Dynamic equation is established between rotor and stator to represent the synchronization error in [10].…”

Identificación de parámetros en tiempo real de un motor de CD de imanes permanentes sin escobillas

“…conocida como método de prelocalización [30][31][32]. Esta técnica es comúnmente utilizada en el uso de controladores sin sensores, debido a que se tiene que tener certeza en la posición inicial del rotor para poder operarlo de manera segura.…”

“…Para determinar los parámetros correspondientes a la ecuación mecánica (2.34b) se realizaron pruebas de arranque en vacío a distintas velocidades. El arranque del motor se realizó utilizando el método de prelocalización [30], alimentando las fases correspondientes a H b = 1 y H c = 1. La operación a distintas velocidades si hizo utilizando el control escalar del motor BLDC descrito en la sección 3.2.2.…”