Combined Power and Attitude Control System for Low Earth Orbit Satellites

Abstract

Flywheel power systems are now seen as a technology that can be used in various applications, including low-earth space satellite orbits, pulse transmission for hybrid electric vehicles and many other applications. In consideration of the energy storage feature, a flywheel device has great advantages over chemical batteries for Low Earth Orbit (LEO) satellites: lifespan, density of power, short charge time, wide operational temperature band, and deep depth of discharge. Flywheel systems have significant advantages over chemical batteries also it can be used to control the spacecraft attitude. The combination of power and attitude control is a practical solution for small satellites to enhance space missions. Double counter-rotating flywheels mounted on an air table are introduced in this paper to execute the control system of combined power and single-axis attitude control. The system control technique of integrated power and attitude control could be implemented based either on a speed control mode or on a torque control mode. The control algorithm’s method is known as field orientation control. This method offers the flywheel motor / generator with precise and high bandwidth torque control by controlling rotor reference frame currents that are dc in steady-state. The Permanent magnet synchronous motor/generator is regulated by the direction of the field. The current rotational frame of the d-axis is ordered to zero and the current order of the q-axis rotational frame of reference differs to maintain dc bus regulation and control of attitude. MATLAB Simulink is used to model the combined power and single-axis attitude control system using two similar flywheels. Furthermore, different cases and different modes of operation are presented which showed that flywheels behavior changed according to different operations.