Control of an Electronic Expansion Valve Using an Adaptive Pid Controller
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Control of an Electronic Expansion Valve Using an Adaptive PID Controller
Antônio A. T. Maia*, Marconi A. Silva, Ricardo N. N. Koury, Luiz Machado, Alexandre C. Eduardo
Federal University of Minas Gerais, Mechanical Engineering Department,
Belo Horizonte, Minas Gerais, Brazil
Phone: + (55 31) 3409 6667, Fax: + (55 31) 3443 3783, e-mail: aamaia@ufmg.br
ABSTRACT
In many refrigeration systems, electronic expansion devices have been used to replace the conventional expansion devices like capillary tubes and thermostatic expansion valves. The electronic expansion devices are usually provided with an automatic controller that is responsible for determining the valve opening that keeps the superheat at the outlet of the evaporator within the desired limits. Most of these controllers permit only the adjustment of the desired superheat, the proportional, the integral and the derivative gains. After being adjusted for one operating point, these parameters do not suffer any automatic correction even when the operating conditions changes. This could penalize the system efficiency because the controller parameters defined initially may not be the most suitable for the system when operating in this new condition. Within this context, in this work it was developed an adaptive
PID-controller to regulate the superheat degree at the outlet of the evaporator. A dynamic model obtained from experimental tests was used in the controller design. The controller effectiveness was evaluated by means of computer simulation and through experimental tests. The results obtained showed that the employed technique is effective in regulating the superheat degree at the outlet of the evaporator with an acceptable performance.
1. INTRODUCTION
The increase in the energy prices in the last decades has motivated many research works to identify great energy consumers and ways to improve the efficiency of these systems. In this context, refrigerating machines have a
Control of an Electronic Expansion Valve Using an Adaptive PID Controller
Antônio A. T. Maia*, Marconi A. Silva, Ricardo N. N. Koury, Luiz Machado, Alexandre C. Eduardo
Federal University of Minas Gerais, Mechanical Engineering Department,
Belo Horizonte, Minas Gerais, Brazil
Phone: + (55 31) 3409 6667, Fax: + (55 31) 3443 3783, e-mail: aamaia@ufmg.br
ABSTRACT
In many refrigeration systems, electronic expansion devices have been used to replace the conventional expansion devices like capillary tubes and thermostatic expansion valves. The electronic expansion devices are usually provided with an automatic controller that is responsible for determining the valve opening that keeps the superheat at the outlet of the evaporator within the desired limits. Most of these controllers permit only the adjustment of the desired superheat, the proportional, the integral and the derivative gains. After being adjusted for one operating point, these parameters do not suffer any automatic correction even when the operating conditions changes. This could penalize the system efficiency because the controller parameters defined initially may not be the most suitable for the system when operating in this new condition. Within this context, in this work it was developed an adaptive
PID-controller to regulate the superheat degree at the outlet of the evaporator. A dynamic model obtained from experimental tests was used in the controller design. The controller effectiveness was evaluated by means of computer simulation and through experimental tests. The results obtained showed that the employed technique is effective in regulating the superheat degree at the outlet of the evaporator with an acceptable performance.
1. INTRODUCTION
The increase in the energy prices in the last decades has motivated many research works to identify great energy consumers and ways to improve the efficiency of these systems. In this context, refrigerating machines have a
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