Field Balancing and Harmonic Vibration Suppression in Rigid AMB-Rotor Systems with Rotor Imbalances and Sensor Runout

Abstract

Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs), offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, currents, and vibrations also occur in the AMB-rotor system owing to the mixed rotor imbalances and sensor runout. To compensate the rotor imbalances and to suppress the harmonic vibrations, two control methods are presented. Firstly, a four degrees-of-freedom AMB-rotor model with the static imbalance, dynamic imbalance, and the sensor runout are described. Next, a synchronous current reduction approach with a variable-phase notch feedback is proposed, so that the rotor imbalances can be identified on-line through the analysis of the synchronous displacement relationships of the geometric, inertial, and rotational axes of the rotor. Then, the identified rotor imbalances, which can be represented at two prescribed balancing planes of the rotor, are compensated by discrete add-on weights whose masses are calculated in the vector form. Finally, a repetitive control algorithm is utilized to suppress the residual harmonic vibrations. The proposed field balancing and harmonic vibration suppression strategies are verified by simulations and experiments performed on a control moment gyro test rig with a rigid AMB-rotor system. Compared with existing methods, the proposed strategies do not require trial weights or an accurate model of the AMB-rotor system. Moreover, the harmonic displacements, currents, and vibrations can be well-attenuated simultaneously.

Elimination of Harmonic Force and Torque in Active Magnetic Bearing Systems with Repetitive Control and Notch Filters

“…According to the gyro technique equations and Newton’s second law, the dynamics of the AMB system in the radial four DOF can be given by [26]:$\{\begin{array}{l}m{s}^2{x}_I\left(s\right)=2\left[k_x-2k_i{k}_s{G}_w\left(s\right)C_t\left(s\right)\right]\left[x_I\left(s\right)-\Delta x\left(s\right)\right]-2k_i{G}_w\left(s\right)C_t\left(s\right)x_{sr}\left(s\right)\\ m{s}^2{y}_I\left(s\right)=2\left[k_x-2k_i{k}_s{G}_w\left(s\right)C_t\left(s\right)\right]\left[y_I\left(s\right)-\Delta y\left(s\right)\right]-2k_i{G}_w\left(s\right)C_t\left(s\right)y_{sr}\left(s\right)\end{array}$ $\{\begin{array}{c}{J}_r{s}^2{\alpha }_I\left(s\right)+J_z\Omega s{\beta }_I\left(s\right)=2\left[k_x{l_m}^2-k_i{k}_s{l}_m{l}_s{G}_w\left(s\right)C_{rs}\left(s\right)\right]\left[{\alpha }_I\left(s\right)-\Delta \alpha \left(s\right)\right]-2k_i{l}_m{G}_w\left(s\right)C_{rs}\left(s\right){\alpha }_{sr}\\ +2k_i{k}_s{l}_m{l}_s{G}_w\left(s\right)C_{rc}\left(s\right)[...\end{array}$…”

Optimization and Experiment of Mass Compensation Strategy for Built-In Mechanical On-Line Dynamic Balancing System

“…Kuen Tai Tsai simultaneously used the influence coefficient method and genetic algorithm to obtain the balance weight and angle plane of each balance so that the balance weight could be placed on multiple balance planes at the same time, which helped to shorten the time of field dynamic balance test and improve the dynamic balance efficiency [10]. Xiangbo Xu et al proposed a synchronous current reduction approach with a variable-phase notch feedback that could identify on-line rotor unbalance, compensate rotor unbalance, and suppress harmonic vibration through the addition of discrete additional weight on two specified balance planes of the rotor [11]. Xu Juan et al proposed a fuzzy self-tuning single neuron PID(Proportion Integration Differentiation) control method in order to improve the control efficiency and balance accuracy of rotor auto-balance, and this method had a faster response time, fewer overshoots, and fewer oscillations [12].…”

Vibration Control of an Unbalanced Single-Side Cantilevered Rotor System with a Novel Integral Squeeze Film Bearing Damper

“…The excitation sources of vibration mainly come from the rotor system and external excitations. The excitation sources of the rotor system include rotor unbalance, misalignment, and friction [3][4][5]. First, the stiffness damping model of the integral squeeze film bearing damper is shown in Figure 2.…”