Improving Disturbance Rejection in Nonlinear Active Magnetic Bearing Systems: Using Lur'e Formulation

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Ali Gerami ◽  
Roger Fittro ◽  
Carl Knospe
Keyword(s):  
Disturbance Rejection ◽  
System Approach ◽  
Magnetic Bearing ◽  
Experimental Results ◽  
Active Magnetic Bearing ◽  
Electromagnetic Actuators ◽  
Lur’E System ◽  
Series Of Experiments ◽  
Magnetization Behavior ◽  
Good Agreement

Abstract The efficacy of magnetic bearing controllers designed to reject transient disturbances is evaluated via a series of experiments. The experiment consists of a rocking beam with opposing electromagnetic actuators for control as well as an actuator for applying a disturbance torque. Controller synthesis employed a generalized Lur'e system approach to accommodate the nonlinear magnetization behavior of the electromagnetic actuator iron. Experimental results demonstrate significant improvements in disturbance rejection with controllers based upon the Lur'e system approach. Good agreement between simulation and experimental results was obtained, providing confidence that similar benefits can be achieved in industrial machinery employing active magnetic bearings.

Vibration Mitigation of Rotors Suspended on Low-Cost Hybrid Gas Foil Bearing

2019 ◽  
Author(s):  
Kamal Kumar Basumatary ◽  
Karuna Kalita ◽  
Sashindra K. Kakoty ◽  
Seamus D. Garvey
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Current Source ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Electromagnetic Actuators ◽  
Manufacturing Method ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Small Series

Abstract The hybrid Gas Foil Bearings combining the Gas Foil Bearing and Active Magnetic Bearing is a possibility for application in high-speed turbomachinery and a few developments have been made in this context. As such, the cost of conventional Gas Foil Bearing increases due to its requirement of precise manufacturing method and the coating material for the top foil and bump foil. In case of Active Magnetic Bearing, the normal electrical arrangement includes a multiplicity of independently controlled current sources usually at least four drives per bearing which increases its cost. Therefore, the hybrid Gas Foil Bearing will have much higher cost. In this work, a new electrical arrangement for the electromagnetic actuators of the hybrid Gas Foil Bearing has been proposed. The new arrangement requires only two drives per bearing and the bias current has been provided (in the same set of windings) through a simple rectifier with small series choke and shunt capacitor. As the number of drives required is less, the proposed bearing will have low cost. Implementing the new approach, the force vectors are achieved using only two current-source drives whereas the usual conventional arrangement requires four such drives. Numerical simulations are performed to explore the capabilities of the low cost bearing.

Combination Axial and Radial Active Magnetic Bearing With Improved Axial Bandwidth

2012 ◽  
Author(s):  
Alexei V. Filatov ◽  
Lawrence A. Hawkins
Keyword(s):  
Structural Integrity ◽  
Electrical Current ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Phase Lag ◽  
Axial Loads ◽  
Electromagnetic Actuators ◽  
Current Path ◽  
Force Reduction ◽  
Actuator Design

Homopolar Permanent-Magnet-Biased Combination Axial and Radial Electromagnetic Actuators used in Active Magnetic Bearings (AMBs) have several advantages over arrangements of separate axial and radial actuators including shorter length, lower part count, lower cost and better rotordynamic response. However, these actuators may require higher-order compensators in applications with significant dynamic axial loads due to somewhat lower axial bandwidth. One of the reasons for a lower axial bandwidth is having the axial magnetic control flux flowing through an opening in a radial actuator assembled from insulated electrical-steel laminations stacked axially. Whenever this flux changes in time, it induces an electrical current in each lamination which is responsible for the dynamic axial force reduction and an additional phase lag. In an improved actuator design, a current path in each lamination is interrupted by a single slot located between two radial control poles. In order to maintain structural integrity of the stack and magnetic conductivity between the radial poles, the slot position is rotated by 90 degrees between each subsequent lamination in the stack. The solution has been evaluated in a test actuator with 3000N axial and 1200N radial load capacities. 7dB gain improvement and 15 degrees phase improvement at 30Hz have been demonstrated.

High-Precision Cutting Tool Tracking With a Magnetic Bearing Spindle

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Alexander Smirnov ◽  
Alexander H. Pesch ◽  
Olli Pyrhönen ◽  
Jerzy T. Sawicki
Keyword(s):  
Pid Control ◽  
Disturbance Rejection ◽  
High Speed ◽  
Cutting Tool ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
External Loading ◽  
Reference Tracking ◽  
Tool Position ◽  
Tool Tracking

A method is presented for tool tracking in active magnetic bearing (AMB) spindle applications. The method uses control of the AMB air gap to achieve the desired tool position. The reference tracking problem is transformed from the tool coordinates into the AMB control axes by bearing deflection optimization. Therefore, tool tracking can be achieved by an off-the-shelf AMB controller. The method is demonstrated on a high-speed AMB boring spindle with a proportional integral derivative (PID) control. The hypothetical part geometries are traced in the range of 30 μm. Static external loading is applied to the tool to confirm disturbance rejection. Finally, a numerical simulation is performed to verify the ability to control the tool during high-speed machining.

The Robust Control of Magnetic Suspension with Rapidly Changing of Rotor Speed

2009 ◽  
Vol 147-149 ◽  
pp. 302-307 ◽  
Author(s):  
Arkadiusz Mystkowski ◽  
Zdzisław Gosiewski
Keyword(s):  
Control System ◽  
Robust Control ◽  
High Speed ◽  
Controller Design ◽  
Angular Speed ◽  
Magnetic Bearing ◽  
Magnetic Suspension ◽  
Experimental Results ◽  
Active Magnetic Bearing ◽  
Robust Controller

An optimal robust vibration control of a rotor supported magnetically over a wide angular speed range is presented in the paper. The laboratory stand with the high speed rotor (max. 24000 rpm) was designed. The wide bandwidth controller with required gain, which is necessary to stabilize the structurally unstable and active magnetic bearing system was computed. For controller design, the weighting functions putted on the input and output signals were chosen. For control design, the dynamics of the rotor and uncertain parameters were considered. The optimized control system by minimization of the H norm putted on transient process of the system was presented. The robust controller was designed with considered asymmetrically magnetic bearings, signal limits and power amplifiers dynamic. The success of the robust control is demonstrated through computer simulations and experimental results. Matlab-Simulink was used for the numerical simulation. The experimental results show the effectiveness of the control system as good vibrations reducing and robustness of the designed controller in all dynamic states.

Modal Testing and Parameter Identification of Active Magnetic Bearing System

1995 ◽  
Author(s):  
Chong-Won Lee ◽  
Young-Ho Ha ◽  
Cheol-Soon Kim ◽  
Chee-Young Joh
Keyword(s):  
Parameter Identification ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Magnetic Bearing ◽  
Experimental Results ◽  
Active Magnetic Bearing ◽  
Modal Testing ◽  
Modal Parameters ◽  
Bearing System

Abstract Complex modal testing is employed for parameter identification of a four-axis active magnetic bearing system. In the test, magnetic bearings are used as exciters while the system is in operation. The experimental results show that the directional frequency response function, which is properly defined in the complex domain, is a powerful tool for identification of bearing as well as modal parameters.

Adaptive Bias Current Control in Active Magnetic Bearings for Energy Optimization

2011 ◽  
Author(s):  
Satoshi Ueno ◽  
M. Necip Sahinkaya
Keyword(s):  
Power Consumption ◽  
Control Method ◽  
Optimization Method ◽  
Magnetic Bearing ◽  
Descent Method ◽  
Bias Current ◽  
Current Control ◽  
Experimental Results ◽  
Active Magnetic Bearing ◽  
Steepest Descent Method

This paper introduces an adaptive bias current control method for an active magnetic bearing (AMB). The bearing force is analyzed theoretically, and the dynamic performance of the magnetic bearing for various bias currents is discussed. Then power consumption is analyzed and the optimum bias current that minimizes power consumption is derived. A novel optimization method using a steepest descent method is proposed. This requires less computing power than the former optimization method using a recursive Fourier transform algorithm. Experimental results show that the optimized bias current can be achieved by the proposed method. However, the dynamics of the rotor is affected by the bias current variation. In order to overcome this problem, the effects of parameter errors are investigated and correction methods are introduced. Experimental results show that the rotor dynamics are not affected by the variable bias current if the parameters are corrected. Results are also presented for machine run-up and run-down.

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