Efficient and Robust Rub Control With an Active Auxiliary Bearing

2007 ◽  
Author(s):  
Lucas Ginzinger ◽  
Heinz Ulbrich
Keyword(s):  
Control System ◽  
Control Strategy ◽  
High Efficiency ◽  
Industrial Applications ◽  
Rotor System ◽  
Contact Forces ◽  
Smooth Transition ◽  
Normal Operation ◽  
Control Force ◽  
Auxiliary Bearing

In this contribution, a new approach to control a rubbing rotor by applying an active auxiliary bearing is presented. The auxiliary bearing is attached to the foundation via two unidirectional actuators. The control force is applied indirectly using the auxiliary bearing, only in case of rotor rubbing. During a normal operation state, the feedback control does not interfere with the rotor system at all. A robust control system has been developed which significantly reduces the intensity of rubbing by stabilizing the rotor system and assuring an optimal rubbing state in case of a too large rotor amplitude. The two-phase control strategy guarantees a smooth transition from free rotor motion to the state of synchronous full annular rub. A test rig has been developed to experimentally verify the control system. Various experiments show the success of the control strategy. In case of rubbing, the contact forces are reduced up to 80 per cent, which results in significantly lower loads. At the same time, the rotor deflection is decreased too. For industrial applications, the activation of the control system can be operated fully automatically. The high efficiency of the control algorithm allows an implementation on microcontrollers. The developed control of the auxiliary bearing reduces the load and the noise of the system during rotor rubbing significantly.

Feedback Control to Prevent Damage by Rotor Rubbing After an Impact Load

2009 ◽  
Author(s):  
Lucas Ginzinger ◽  
Benjamin Heckmann ◽  
Heinz Ulbrich
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Control Strategy ◽  
Impact Load ◽  
Operation Mode ◽  
Rotor System ◽  
Contact Forces ◽  
Normal Operation ◽  
Control Force ◽  
Auxiliary Bearing

A new approach to control a rubbing rotor by applying an active auxiliary bearing has been developed. The control force is applied indirectly using the auxiliary bearing, only in case of rotor rubbing. The auxiliary bearing is actuated using two unidirectional actuators. A three-phase control strategy has been developed which stabilizes the rotor system in case of an impact load and effectively avoids “backward whirling” which is very destructive. As soon as the load ceased the auxiliary bearing is separated from the rotor again and normal operation mode is continued. During the normal operation state, the feedback control does not interfere with the rotor system at all. A test rig has been developed to experimentally verify the control system. Various experiments show the success of the control strategy. In case of rubbing, the contact forces are reduced up to 95 percent. At the same time, the rotor deflection is decreased too. The activation and deactivation of the control system is operated fully automatically. A simulation framework for an elastic rotor including the non-smooth nonlinear dynamics of contacts is presented, which has been used to develop the feedback controller.

Controller Design for a Rubbing Rotor

2009 ◽  
Vol 147-149 ◽  
pp. 203-214
Author(s):  
Lucas Ginzinger ◽  
Roland Zander ◽  
Heinz Ulbrich
Keyword(s):  
Controller Design ◽  
Experimental Studies ◽  
Feedback Controller ◽  
Contact Forces ◽  
Smooth Transition ◽  
Control Force ◽  
Simulation Environment ◽  
Two Phase ◽  
New Approach ◽  
Auxiliary Bearing

A new approach to control a rubbing rotor by applying an active auxiliary bearing is developed. The auxiliary bearing is attached to the foundation via two unidirectional actuators. The control force is applied indirectly using the active auxiliary bearing only in case of rubbing. A framework for the development of a feedback controller for an active auxiliary bearing is presented. The theory of a robust two-phase control strategy which guarantees a smooth transition from free rotor motion to the state of full annular rub is presented. A simulation environment for the elastic rotor and the auxiliary bearing including the non-smooth nonlinear dynamics of the rubbing contact is used to develop the feedback controller. Experimental studies have been carried out at a rotor test rig. Various experiments show the outstanding success of the strategy. In case of rubbing, the contact forces are reduced up to 90%.

On the Control of Synchronous Vibration in Rotor/Magnetic Bearing Systems Involving Auxiliary Bearing Contact

2002 ◽  
Author(s):  
Patrick Keogh ◽  
Matthew Cole ◽  
Necip Sahinkaya ◽  
Clifford Burrows
Keyword(s):  
Controller Design ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Normal Operation ◽  
Design Parameters ◽  
Full Control ◽  
Bearing Contact ◽  
Vibratory Motion ◽  
Auxiliary Bearing ◽  
Bearing Design

During the normal operation of rotor/magnetic bearing systems, contacts with auxiliary bearings or bushes are avoided. However, auxiliary bearings are required under abnormal conditions and in malfunctions situations to prevent contact between the rotor and stator laminations. Studies in the open literature deal largely with rotor drop and the requirements of auxiliary bearing design parameters for safe run-down. Rotor drop occurs when the rotor is de-levitated and no further means of magnetic bearing control is available. This paper considers the case when full control is still available and rotor/auxiliary bearing contact has been induced by an abnormal operating condition or temporary fault. It is demonstrated that events leading to contact from a linearly stable rotor orbit can drive the rotor into a non-linear vibratory motion involving persistent contacts. Furthermore, the phase of the measured vibration response may be changed to such an extent that synchronous controllers designed to minimize rotor vibration amplitudes will worsen the rotor response, resulting in higher contact forces. A modified controller design is proposed and demonstrated to be capable of returning a rotor from a contacting to a non-contacting state.

Thermal Assessment of Dynamic Rotor/Auxiliary Bearing Contact Events

2006 ◽  
Vol 129 (1) ◽  
pp. 143-152 ◽  
Author(s):  
Patrick S. Keogh ◽  
Woon Yik Yong
Keyword(s):  
Contact Area ◽  
Initial Conditions ◽  
Frictional Heating ◽  
Thermal Response ◽  
Dynamic Contact ◽  
Contact Forces ◽  
Normal Operation ◽  
Permanent Loss ◽  
Auxiliary Bearing ◽  
Transient Thermal

Under normal operation, a rotor levitated by magnetic bearings will rotate without making contact with any stator component. However, there are a number of circumstances that may lead to temporary or permanent loss of levitation. These include full rotor drop events arising from power loss, momentary fault conditions, sudden changes in unbalance, high levels of base acceleration, and other aerodynamically induced force inputs. The spinning rotor will come into dynamic contact with an auxiliary bearing. Highly localized and transient temperatures will arise from frictional heating over the dynamically varying contact area. Rotor dynamic contact forces are predicted for a range of initial conditions leading to combinations of bounce and rub motion on the auxiliary bearing. The transient heat flux from the contact area is then ascertained. A transient thermal Green’s function is developed in a form that is effective over short or long time scales and local to the source. This enables the transient thermal response of an auxiliary bearing to be assessed for a range of dynamic contact conditions. Auxiliary bearings consisting of fixed bushings and free to rotate inner races are analyzed. The results show that significant localized contact temperatures may arise from each contact event, which would accumulate for multiple contact cases. The methodology will be of relevance for the life prediction of auxiliary bearing designs.

WNN Optimizing PID Controller for BLDC Control System

2013 ◽  
Vol 278-280 ◽  
pp. 1529-1532
Author(s):  
Hong Pei Han ◽  
Wu Wang
Keyword(s):  
Neural Network ◽  
Control System ◽  
Pid Control ◽  
Pid Controller ◽  
High Efficiency ◽  
Good Control ◽  
Industrial Applications ◽  
Wavelet Neural Network ◽  
Control Effect ◽  
Pid Tuning

Brushless DC motors (BLDC) are widely used for many industrial applications because of their high efficiency, high torque and low volume. This paper presents the PID control for BLDC Motor, because good control effect cannot be acquired by using the traditional PID control in the non-linear variable time servomechanism and it is difficult to tune the parameters and get satisfied control characteristics, some intelligent techniques should be taken. Wavelet Neural Network (WNN) was constrictive and fluctuant of wavelet transform and has self-study, self adjustment and nonlinear mapping functions of neural networks, So, a wavelet neural network self-tuning proportional-integral-derivative (PID) controller was proposed. The structure of WNN and PID tuning with WNN was presented and the equivalent circuit of BLDC and its mathematical models was analyzed, the simulation was taken with new method, the efficiency and advantages of this control strategy was successfully demonstrated which can applied into BLDC control system.

The Optimization Research on Vehicle ESP Control Strategy

2013 ◽  
Vol 321-324 ◽  
pp. 1548-1553
Author(s):  
Liang Hong Zhao ◽  
Ai Min Fan ◽  
Ling Qin
Keyword(s):  
Control System ◽  
Control Strategy ◽  
Control Algorithm ◽  
Stability Control ◽  
Control Force ◽  
Electronic Stability Program ◽  
Longitudinal Control ◽  
Entire Vehicle ◽  
Car Security ◽  
Controlled Object

Electronic Stability Program (ESP) is an advanced initiative system for car security. As an integration of subsystems such as ABS, TCS, ESC, etc., this new control system is designed to accurately manipulate the dynamics behaviors of vehicles under critical adhesive conditions, allowing maximum cooperation of vehicles responses to the driver's operation within physical limits. This research has firstly established a dynamical model of an entire vehicle as the controlled object in this study of ESP. Then, the paper moved on to the design of ESP control algorithm strategy, discussing the selection problem of which wheels should the longitudinal control force apply to, and finally proposing an effective improvement on operational stability control of ESP system.

scholarly journals Motion coordination control of planar 5R parallel quadruped robot based on SCPL-CPG

2022 ◽  
Vol 14 (1) ◽  
pp. 168781402110709
Author(s):  
Mingfang Chen ◽  
Kangkang Hu ◽  
Yongxia Zhang ◽  
Fengping Qi
Keyword(s):  
Control System ◽  
Control Strategy ◽  
Robot Control ◽  
Quadruped Robot ◽  
Smooth Transition ◽  
Analysis Method ◽  
Motion Coordination ◽  
Connection Weight ◽  
Unit Model ◽  
Hopf Oscillator

The parallel leg of the quadruped robot has good structural stiffness, accurate movement, and strong bearing capacity, but it is complicated to control. To solve this problem, a series connection of parallel legs (SCPL) was proposed, as well as a control strategy combined with the central pattern generator (CPG). With the planar 5R parallel leg as the research object, the SCPL analysis method was used to analyze the leg structure. The topology of CPG network was built with the Hopf oscillator as the unit model, and the CPG was the core to model the robot control system. By continuously adjusting the parameters in the CPG control system and changing the connection weight, and the smooth transition between gaits was realized. The simulation results show that the SCPL analysis method can be effectively used in the analysis of parallel legs, and the control system can realize the smooth transition between gaits, which verifies the feasibility and effectiveness of the proposed control strategy.

scholarly journals Development of a Test Rig and Experimental Verification of the Performance of HSFDs for Active Control of Rotors

1995 ◽  
Author(s):  
A. El-Shafei ◽  
M. El-Hakim
Keyword(s):  
Control System ◽  
Active Control ◽  
Control Strategy ◽  
Computer Control ◽  
Pressure Control ◽  
Open Loop ◽  
Rotor System ◽  
Squeeze Film ◽  
Test Rig ◽  
Experimental Development

This paper summarizes the experimental development of hybrid squeeze film dampers (HSFDs) for active control of rotor vibrations. In a recent paper (El-Shafei and Hathout, 1994) it was shown that the automatically controlled HSFD can be a very useful device for the active control of rotors. A complete mathematical model of the open-loop system was developed. An on-off control strategy based on speed feedback was proposed and was shown by the simulation results to be quite effective in controlling the rotor vibrations. In this paper, the development of a test rig for the experimental investigation of the HSFD-rotor system is presented. The design of the test rig, the HSFD and the rotor system are discussed. The experimental set-up consists of the rotor-HSFD system controlled through a pressure control servovalve for controlling the pressure in the sealing chambers. The hydraulic circuit is controlled through a digital computer with a data acquisition and control system. The on-off control strategy with feedback on speed is implemented on the computer control system and is shown to be quite effective in controlling the first mode of vibration of the rotor system.

On the Control of Synchronous Vibration in Rotor/Magnetic Bearing Systems Involving Auxiliary Bearing Contact

2004 ◽  
Vol 126 (2) ◽  
pp. 366-372 ◽  
Author(s):  
P. S. Keogh ◽  
M. O. T. Cole ◽  
M. N. Sahinkaya ◽  
C. R. Burrows
Keyword(s):  
Controller Design ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Normal Operation ◽  
Design Parameters ◽  
Rotor Vibration ◽  
Full Control ◽  
Bearing Contact ◽  
Vibratory Motion ◽  
Auxiliary Bearing

During the normal operation of rotor/magnetic bearing systems, contacts with auxiliary bearings or bushes are avoided. However, auxiliary bearings are required under abnormal conditions and in malfunction situations to prevent contact between the rotor and stator laminations. Studies in the open literature deal largely with rotor drop and the requirements of auxiliary bearings design parameters for safe rundown. Rotor drop occurs when the rotor is delevitated and no further means of magnetic bearing control is available. This paper considers the case when full control is still available and rotor/auxiliary bearing contact has been induced by an abnormal operating condition or a temporary fault. It is demonstrated that events leading to contact from a linearly stable rotor orbit can drive the rotor into a nonlinear vibratory motion involving persistent contacts. Furthermore, the phase of the measured vibration response may be changed to such an extent that synchronous controllers designed to minimize rotor vibration amplitudes will worsen the rotor response, resulting in higher contact forces. A modified controller design is proposed and demonstrated to be capable of returning a rotor from a contacting to a noncontacting state.

scholarly journals Investigation of Control Characteristics for a Molten Salt Reactor Plant under Normal and Accident Conditions

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5279
Author(s):  
Run Luo ◽  
Chunyu Liu ◽  
Rafael Macián-Juan
Keyword(s):  
Control System ◽  
Molten Salt ◽  
Control Strategy ◽  
Liquid Fuel ◽  
Normal Operation ◽  
Temperature Control System ◽  
Molten Salt Reactor ◽  
Carrier Fluid ◽  
Operation Conditions ◽  
Accident Conditions

A molten salt reactor (MSR) has unique safety and economic advantages due to the liquid fluoride salt adopted as the reactor fuel and heat carrier fluid. The operation scheme and control strategy of the MSR plant are significantly different from those of traditional solid-fuel reactors because of the delayed neutron precursors drift with the liquid-fuel flow. In this paper, a simulation platform of the MSR plant is developed to study the control characteristics under normal and accident conditions. A nonlinear dynamic model of the whole system is built in the platform consisting of a liquid-fuel reactor with a graphite moderator, an intermediate heat exchanger and a steam generator. A new control strategy is presented based on a feed-forward and feedback combined scheme, a power control system and a steam temperature control system are designed to regulate load changes of the plant. Three different types of operation conditions are simulated with the control systems, including transients of normal load-follow operation, a reactivity insertion accident and a loss of flow accident. The simulation results show that the developed control system not only has a fast load-follow capability during normal operation, but also has a good control performance under accident conditions.

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