Optimum loop transfer function in single-loop minimum-phase feedback systems

1973 ◽  
Vol 18 (1) ◽  
pp. 97-113 ◽  
Author(s):  
ISAAC HOROWITZ
Keyword(s):  
Transfer Function ◽  
Minimum Phase ◽  
Feedback Systems ◽  
Single Loop ◽  
Loop Transfer Function

scholarly journals Relative Stability of Electrical into Mechanical Conversion with BLDC Motor-Cascade Control

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 704
Author(s):  
Sylwester Sobieraj ◽  
Grzegorz Sieklucki ◽  
Józef Gromba
Keyword(s):  
Transfer Function ◽  
Relative Stability ◽  
Power Supply System ◽  
Theoretical Calculations ◽  
Electrical Energy ◽  
Cascade Control ◽  
Bldc Motor ◽  
Cascade System ◽  
Loop Transfer Function ◽  
Basic Parameters

The conversion of the electrical energy into the mechanical is usually realized by a motor, power electronics and cascade control. The relative stability (Θ-stability), i.e., the displacement of its eigenvalues of this system is analyzed for a drive with a BLDC motor. The influence of changing the basic parameters of the motor and power supply system on the drive operation is considered. 4th order closed-loop transfer-function of the cascade control is presented, where boundaries of the transfer-function coefficients are used. The cascade system which uncertainty of the resistance, inductance, flux and gain parameters is analyzed. Theoretical calculations for the cascade control, simulations and laboratory tests are included in the article.

On the Vibration of a Translating String Coupled to Hydrodynamic Bearings

1990 ◽  
Vol 112 (3) ◽  
pp. 337-345 ◽  
Author(s):  
C. A. Tan ◽  
B. Yang ◽  
C. D. Mote
Keyword(s):  
Control System ◽  
Transfer Function ◽  
Spatial Location ◽  
System Response ◽  
Thickness Variation ◽  
Translation Speed ◽  
Impedance Function ◽  
Hydrodynamic Bearing ◽  
Loop Transfer Function ◽  
Bearing Force

The vibration of a translating string, controlled through hydrodynamic bearing forces, is analyzed by the transfer function method. Interactions between the string response and the bearing film are described by the bearing impedance function. This function depends on the string translation speed, the frequency of the film thickness variation, and the spatial location of the bearings. The control system consists of the translating string, bearings, actuators and sensors, and feedback elements. An integral formulation of the controlled system response is proposed that leads to the closed-loop transfer function. The frequency response of the control system is studied in the system parameter space. The feasibility of adding active control to improve the bearing force control is also considered.

Robust Feedback Control of a Baffled Plate via Open-Loop Optimization

2001 ◽  
Vol 124 (1) ◽  
pp. 154-157 ◽  
Author(s):  
P. De Man ◽  
A. Franc¸ois ◽  
A. Preumont
Keyword(s):  
Genetic Algorithm ◽  
Control System ◽  
Transfer Function ◽  
Open Loop ◽  
Displacement Sensor ◽  
Search Procedure ◽  
Loop Optimization ◽  
Loop Transfer Function ◽  
Poles And Zeros ◽  
Siso System

A SISO control system is built by using a volume displacement sensor and a set of actuators driven in parallel with a single amplifier. The actuators location is optimized to achieve an open-loop transfer function which exhibits alternating poles and zeros, as for systems with collocated actuators and sensors; the search procedure uses a genetic algorithm. The ability of a simple lead compensator to control this SISO system is numerically demonstrated.

Model-Based Control of Combustion Instabilities

2005 ◽  
Author(s):  
Aimee S. Morgans ◽  
Ann P. Dowling
Keyword(s):  
Transfer Function ◽  
Controller Design ◽  
Open Loop ◽  
Operating Conditions ◽  
Combustion Instabilities ◽  
Lean Premixed Combustion ◽  
Model Based Control ◽  
Model Based ◽  
Loop Transfer Function ◽  
Mathematical Approximation

Model-based control has been successfully implemented on an atmospheric pressure lean premixed combustion rig. The rig incorporated a pressure transducer in the combustor to provide a sensor measurement, with actuation provided by a fuel valve. Controller design was based on experimental measurement of the open loop transfer function. This was achieved using a valve input signal which was the sum of an identification signal and a control signal from an empirical controller to eliminate the non-linear limit cycle. The transfer function was measured for the main instability occurring at a variety of operating conditions, and was found to be fairly similar in all cases. Using Nyquist and H∞-loop shaping techniques, several robust controllers were designed, based on a mathematical approximation to the measured transfer function. These were implemented experimentally on the rig, and were found to stabilise it under a variety of operating conditions, with a greater reduction in the pressure spectrum than had been achieved by the empirical controller.

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