Study On Control Technologies Of Magnetically Suspended Gimballing Momentum Wheel

Magnetically suspended gimballing momentum wheel(MSGMW)is a novel inertial actuator with the capacity of providing torques among all the three axes.Only one MSGMW can stabilize a satellite in a small attitude range around the nominal status.This dissertation focuses on the key control technologies of the MSGMW,including suspending and titling control,titling motion stability analysis,active vibration control,control system implementation and space application.The main contributions and innovations are listed as follows.(1)The control system model of MSGMW is built and the suspending and titling controllers are designed.Firstly,the main structure and principle of MSGMW are introduced and the control system model is established.Secondly,we design a PID controller for the suspending control of the racial hybrid magnetic bearing(RHMB)and a decoupled PID controller for the titling control of the titling Ampere force magnetic bearings(TAFMB),respectively.Thirdly,an identification method for the current stiffness coefficient and the displacement stiffness coefficient is proposed,and the TAFMB is used to measure the titling passive stiffness of the RHMB.At last,based a novel 3-phase Y-connected TAFMB designed,the space voltage pulse width modulating(SVPWM)for the current control is proposed,and simulations demonstrate the feasibility of titling control by the 3-phase Y-connected TAFMB.(2)A novel extended Nyquist criterion is proposed based on the complex coefficient transfer function,which is used for the stability analysis of the MBRS and the derivation of the speed stable region.At first,The complex coefficient transfer function is employed to model a class of the second-order anti-symmetric gyro-coupled and the time-delayed systems.Then,the extended Nyquist criterion and the relative stable region theory are proposed.An example is employed to verify the criterion and the theory and illustrate the detailed calculation process.Subsequently,the characteristics of the complex coefficient transfer function of a MBRS are analyzed carefully.Finally,the new criterion is used to study the absolute stability and solve the speed stable region of the titling motion of the MBRS.(3)The mechanism of active vibration control methods which are used to suppress the vibrations coursed by rotor’s unbalance,SR and MR for the MBRS,are studied systematically.We first study three structures of synchronous signal processing methods,i.e.,the adaptive synchronous signal amplifier(ASSA),the adaptive synchronous signal notch filter(ASSNF),and the adaptive synchronous signal pass filter(ASSPF).Based on the single-frequency analysis method,the zero synchronous displacement/angle control(ZSDC/ZSAC),zero synchronous current control(ZSCC)and zero synchronous force/torque control(ZSDC/ZSAC)are given.And the stability of the three vibration controllers is examined via the classical roots locus method and simulations.Then,we analyze the mechanisms of vibrations coursed by sensor runout and magnet runout and conclude that the ZSFC cannot completely suppress the synchronous force simultaneously when considering SR&MR.In addition,an identification method of the difference between SR and MR based on a low rotating speed condition,and a modified ZSFC with compensating the SR&MR online are proposed,respectively.Finally,theoretical analysis indicates that the AFMB has inherent advantages of conducing active vibration control to suppress the force vibration.(4)The implementation of the control system of the MSGMW,the active vibration experiments and the space application technology are studied systematically.In order to control the suspension and titling motion,we design a DSP+FPGA controller,as well as the hardware and software of the control system.We further propose an optocoupler bootstrap H-bridge with N-Mosfets to simplify the driven circuit,and give a three-level scheme to eliminate the current noise and power consumption.Based on the designed control system,the active vibration control experiments,including ZSDC,ZSCC and ZCC,are conducted to verify the effectiveness of the proposed methods.