Patent ID: 7512466

Claim:
A spacecraft attitude control apparatus, comprising: first and second reaction wheel assemblies (RWA) comprising: first and second reaction wheels; first and second motor-generators (M/Gs) rotationally coupled to the first and second reaction wheels, respectively, for adding energy to or removing energy from the first and second reaction wheels, respectively; and first and second power flow controllers electrically coupled to the first and second M/Gs respectively, and adapted to control operation of the first and second M/Gs as motors or generators; and a power bus coupling to the first and second power flow controllers of the first and second RWAs for transferring energy between the first and second M/Gs, whereas when a torque command is received requiring that the first RWA decelerate and the second RWA accelerate, the first power flow controller configures the first M/G as a decelerating generator and the second power flow controller configures the second M/G as an accelerating motor and power flows from the decelerating first M/G to the accelerating second M/G via the power bus while an output voltage derived from the first decelerating M/G exceeds a back EMF of the second accelerating M/G.