Abstract
Reaction wheel is a key component in performing satellite attitude control, and permanent magnet synchronous motor (PMSM) has been gradually employed as its actuator owing to many advantages. This dissertation presents the development of a digital signal processor (DSP)-based PMSM driven satellite reaction wheel, its DC-link voltage is adjustable in accordance with wheel speed and varied photovoltaic cell voltage to yield good driving performance under wide speed range. First, the dynamical model of the PMSM driven reaction wheel is established with the key parameters being estimated. Accordingly, the novel current controlled PWM scheme is developed. The conventional proportional plus integral (PI) control is augmented with internal model resonant control (IMRC) and robust error cancellation controller to yield precise transient and steady-state sinusoidal current tracking characteristics under sinusoidal speed-dependent back electromotive force (EMF). And the tracking control performance is insensitive to system operating condition and parameter changes. Then the robust torque control of the PMSM driven reaction wheel is performed to yield quick observed torque control response. As to the speed control loop, a feedback controller is first quantitatively designed at nominal case according to the estimated dynamic plant model and the defined reference response. As the changes of system operating conditions are occurred, a simple robust speed error cancellation control scheme is developed to preserve the defined response trajectory. For larger speed command change, the ramp command with suited ramping rate is arranged to avoid long duration control effort saturation. Meanwhile, an observed disturbance is obtained using the nominal inverse motor drive model, and it is employed to estimate the wheel frictional condition. Finally, to provide adjustable and well-regulated DC-link voltage from the fluctuated photovoltaic DC source voltage, a DC-DC boost and a DC-DC buck-boost front-end converters are established and comparatively evaluated their effectiveness in enhancing the followed PMSM driven wheel performances under wide speed range. In addition, the chopping dynamic braking mechanism is also equipped to yield stable braking operation.