CONTINUOUS FREQUENCY METER FOR A REACTION WHEEL

Abstract

The usage of reaction wheels as executive parts for control systems of angular orientation and stabilization of spacecraft remains the most widespread method of angular control for a satellite. To create highly effective control system rigid demands are pulled out for reaction wheels such as mass-size characteristic, proportionality of reaction momentum to control signal and minimization power losses during energy transformation.The biggest errors in recreation of control law of reaction wheels take place during rotor angular velocity sign change, as in this moment compensation systems do not decrease but increase the influence of back EMF and friction momentum until the moment the information about angular velocity is renovated. When the angular velocity crosses the null pulsation of reaction momentum takes place. This problem is more important for reaction wheels of micro- and nano- level, as their small size limits the number of poles of the magnetic system and thus the number of information renovation points is small.The article is dedicated to the method of formation of quasi-stationary signal of rotor rpm of compact reaction-wheel, built on the basis of 2-and 4-pole three-phase brushless DC motors. The proposed approach allows the use of rotor position sensor signals to form a signal of rotor rpm of reaction-wheel and eliminate the error of reproduction of control law for reaction-wheel when the sign of the angular velocity of rotation of the rotor changes.