Nonlinear control considering temperature dependence of thermal conductivity for a cooling and heating system based on the concept of sliding mode

Author(s):  
Akihiro Yamakita ◽  
Mingcong Deng
Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 174
Author(s):  
Ryo Chikaraishi ◽  
Mingcong Deng

Recently, the development of SiC and GaN high-performance semiconductor devices has led to higher efficiency in power conversion equipment. In order to perform thermal design of power conversion equipment and evaluation of the equipment, it is necessary to measure the power loss of the equipment with high accuracy. In a previous study, a system to measure the power loss from the amount of heat emitted from power conversion devices using a Peltier device was proposed. In this study, aiming to improve the measurement accuracy, the temperature dependence of the thermal conductivity of a Peltier device, which was treated as a constant value in the previous study, was considered. The control system considering the temperature dependence of the thermal conductivity was designed based on operator theory, which is a nonlinear control theory. The simulation and experimental results show that the measurement accuracy was improved when the power loss was 10 W and 15 W compared to the case without considering the temperature dependence. In addition, the measurement time was reduced by about 100 s by considering the temperature dependence. The effectiveness of the proposed system was shown when the power loss was 10 W and 15 W.


Author(s):  
Ehsan Tarkesh ◽  
Mohammad Elahinia

This paper is aimed toward the development and evaluation of a novel active ankle foot orthosis (AAFO) based on shape memory alloy (SMA) actuators. This device intends to fill the gap in the existing research aimed at helping patients with drop foot muscle deficiencies as well as rehabilitation activities. To check the feasibility of this idea, a brief study is done on the dynamic behavior of ankle joint and then an SMA manipulator with a similar biological concept is used for experiment. Nonlinear behavior of SMA wires requires nonlinear control techniques such as Sliding Mode Controller (SMC) for tracking the desired ankle angle. Simulation results of three different techniques are compared (PID, SMC and SMC-PID) and finally the experimental result of a SMC-PID switching control is provided. This results shows that a switching control between simple PID and Sliding Mode Control can be a good alternative to follow the desired trajectory in slow walking cycles.


1977 ◽  
Vol 32 (5) ◽  
pp. 530-532 ◽  
Author(s):  
N. B. Vargaftik ◽  
L. V. Yakush

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