μ-Synthesis Controller Design Based on Structured Uncertainty of a Variable Speed Refrigeration System for Robust Temperature Control

2021 ◽  
Vol 33 (12) ◽  
pp. 619-632
Author(s):  
In A Kim ◽  
Seok Kwon Jeong
Keyword(s):  
Temperature Control ◽  
Controller Design ◽  
Variable Speed ◽  
Refrigeration System ◽  
Structured Uncertainty

scholarly journals Robust Temperature Control of a Variable-Speed Refrigeration System Based on Sliding Mode Control with Optimal Parameters Derived Using the Genetic Algorithm

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6321
Author(s):  
Jieun Lee ◽  
Seokkwon Jeong
Keyword(s):  
Genetic Algorithm ◽  
Kalman Filter ◽  
Temperature Control ◽  
Sliding Mode ◽  
Design Parameters ◽  
Trial And Error ◽  
Variable Speed ◽  
Refrigeration System ◽  
Saturation Function ◽  
Feedforward Controller

A sliding mode control (SMC) technique based on a state observer with a Kalman filter and feedforward controller was established for a variable-speed refrigeration system (VSRS) to ensure robust control against model uncertainties and disturbances, including noise. The SMC was designed using a state-space model transformed from a practical transfer function model, which was derived by conducting dynamic characteristic experiments. Fewer parameters affecting the model uncertainty were required to be identified, which facilitated modeling. The state observer for estimating the state variables was designed using a Kalman filter to ensure robustness against noise. A feedforward controller was added to the control system to compensate for the deterioration in the transient characteristics due to the saturation function used to avoid chattering. A genetic algorithm was used to alleviate the trial and error involved in determining the design parameters of the saturation function and select optimal values. Simulations and experiments were conducted to verify the control performance of the proposed SMC. The results show that the proposed controller can realize robust temperature control for a VSRS despite stepwise changes in the reference and external heat load, and avoid the trial and error process to design parameters for the saturation function.

scholarly journals Nonlinear Compound Control for Nonsinusoidal Vibration of the Mold Driven by Servo Motor with Variable Speed

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Qiang Li ◽  
Yi-ming Fang ◽  
Jian-xiong Li ◽  
Zhuang Ma
Keyword(s):  
Control Method ◽  
Controller Design ◽  
Rotation Speed ◽  
Pi Control ◽  
Variable Speed ◽  
Servo Motor ◽  
Motor Speed ◽  
Vector Method ◽  
Compound Control ◽  
The Relationship

In this paper, a fuzzy PI control method based on nonlinear feedforward compensation is proposed for the nonsinusoidal vibration system of mold driven by servo motor, rotated in single direction with variable speed. During controller design, there are mainly two issues to consider: (i) nonlinear relationship (approximate periodic function) between mold displacement and servo motor speed and (ii) uncertainties caused by backlash due to motor variable speed. So, firstly, the relationship between mold displacement and motor rotation speed is built directly based on the rotation vector method. Then, an observer is designed to estimate the uncertainties and feedforward compensation. Secondly, as the motor rotates in single direction with variable speed, a fuzzy control with bidirectional parameter adjustment is adopted to improve rapidity and stability based on the traditional PI method. Finally, some simulation results show the effectiveness of the proposed control method.

A Robust Pressure Controller for a Variable Speed AC Motor Pump: Application to Aircraft Hydraulic Power Packages

2018 ◽  
Author(s):  
Nils Trochelmann ◽  
Phillip Bischof Stump ◽  
Frank Thielecke ◽  
Dirk Metzler ◽  
Stefan Bassett
Keyword(s):  
Distribution Systems ◽  
Controller Design ◽  
Dynamic Performance ◽  
Operating Conditions ◽  
Gear Pump ◽  
Variable Speed ◽  
Hydraulic Power ◽  
Worst Case ◽  
Wide Range ◽  
Pressure Controller

Highly integrated electro-hydraulic power packages with electric motor-driven pumps (EMP) are a key technology for future aircraft with electric distribution systems. State of the art aircraft EMPs are robust but lack efficiency, availability, and have high noise emissions. Variable speed fixed displacement (VSFD-) EMPs, combining a permanent magnet synchronous motor and an internal gear pump, show promising properties regarding noise reduction and energy efficiency. Though, meeting the strict dynamic requirements is tough with this EMP-concept. Speed limitations and inertia impose strong restrictions on the achievable dynamic performance. Moreover, the requirements must be met under a wide range of operating conditions. For a prototype aircraft VSFD-EMP a robust pressure controller design is proposed in this paper. In a first step the operating conditions of the EMP are defined, analyzing environmental conditions and impacts of the interfacing aircraft systems. Nonlinear and linear control design models are developed and validated by measurements at an EMP test rig built for this project. A conventional cascade pressure control concept is selected. This is motivated by the demand for simple, reliable, and proven solutions in aerospace applications. A controller is designed by applying classical loop shaping techniques. Robust stability and performance of the system are investigated through a subsequent μ-analysis. Finally, the controller is tested under nominal and worst case conditions in nonlinear simulations.

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