| Flywheel occupies an important position in attitude control of spacecraft andenergy storage. On background of speed contol of flywheel on spacecraft, a drivingcontrol system is designed in this paper. A novel phase and frequency detector (PFD)based on state machine is designed. Dual close-loop control of phase and current isapplied to realize the drivo and control system of flywheel. Hardware circuit based onFPGA as the controllor is designed to implement high precision speed control.Firstly, the structure of phace-locked loop (PLL) control system including flywheel,PFD and power amplification is determined in this paper. It is pointed that PLL controlsystem is a nonlinear system with saturation characteristic, which can be simplified aslinear system when PFD remains in phased detecting state. Simplied linear systemmodel is designed and the dynamic stability of nonliear system is proved.Secondly, the drivo and control system for flywheel is designed. A novel PFD withcounter for detecting of phase error and state machine for frequency detecting whichperforms better linear property is proposed. Dual close-loop control system of phase andcurrent is designed, with simulation proving that dual close-loop system reduces thetorque fluctuation and performs higher speed precision. Approximating sinus drivingmethod based multi-hall sensors and exact sinus method based on position-prediction isproposed to get even lower torque fluctuation.Furthermore, the hardware circuit based on FPGA is accomplished. Control systemis designed with verilog HDL, including PFD, dual-loop controllor and drivo logiccontrollor. Drivo circuit is designed with integration module of MOSFET.Finally, the test results are given and anaylzed. The experiments justify thatprecision of flywheel control system can achieves0.033%with the novel PFD and0.017%with the sinus-drivo method. Slope commands of200rpm/scan be trackedperfectly by the control system. Dual close-loop control system induces the outputtorque fluctuation and improves the performance of speed control. |
