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Reset Control of Pressure-Drop Oscillations in Boiling Micro-Channel Systems
Masataka Iwai,Toshimitsu Ushio 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
A micro-channel has become a popular scheme in high heat flux electronics cooling. But boiling flow instabilities can occur in these cooling systems with micro-channel heat sinks. These pressure-drop oscillations are limit cycles. We model the system by a van der Pol equation with a control input, which is represented by a control system with a nonlinear feedback element. Using a describing function, we approximate the pressure-drop oscillation in the boiling micro-channel system controlled by a reset controller. Then we obtain a control parameter region where the pressure-drop oscillation is eliminated by the controllerBy simulation, we also show that the pressure-drop oscillation is eliminated by the reset controller.
Van der Pol filter of chaotic vortex signal in vortex flowmeter
Masataka Iwai 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
Vortex flowmeters are widely used in industrial plants. But vortex meters instabilities under low flow rate condition and the presence of external disturbance are not satisfactorily addressed, and form the subject of our investigation. Some of these signal instabilities are chaotic oscillations which may occur due to fluid pulsations via rotating machines such as fuel gas compressors. We model the chaotic vortex signal and the filter system of this signal with a coupled van der Pol equation system. Using a describing function and a frequency entrainment condition, we obtain a filter parameter where the vortex signal can be demodulated to the correct frequency signal. By simulation, we show the proposed filter parameter for the model will be demodulated to the correct signal. We also show this method for the chaotic vortex signal data of the vortex flowmeter which occurred in the actual plant. We also show that the chaotic vortex signal of the actual plant can be demodulated to the correct frequency.
Reset Control of Combustion Oscillation in Lean Premixed Combustor
Masataka Iwai 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10
Combustion oscillations occur themselves as pressure and heat release oscillations in lean premixed combustors, and may cause some unexpected damage. This paper proposes a design method of a reset controller to eliminate a combustion oscillation in a lean premixed combustor model. We consider a plant model consisting of a linear system with a nonlinear feedback element and a reset controller using a first-order lag element, which is called a first-order reset element (FORE). We show parameter conditions of the reset controller for which limit cycles are eliminated, using a describing function of the nonlinear element. We apply the proposed design method of the reset controller and a flame describing function to eliminate the combustion oscillation in the lean premixed combustor model and show its effectiveness appropriately.
Prediction of Limit Cycles in Nonlinear Systems with Reset Controllers Using Describing Function
Masataka Iwai,Toshimitsu Ushio 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10
In nonlinear systems, limit cycles may exsist in some’s parameters and may cause some unexpected damage. This paper proposes a design method of a reset controller for the Reset control of limit cycles. We consider a plant consisting of a linear system with a nonlinear feedback element and show a condition of the parameter for which limit cycles exists, using describing functions of the nonlinear element and the reset controller. The adjustable parameter of the reset controller is determined by the intersection of the inverse Nyquist locus of the linear system and the existence region of the limit cycles on the complex plain. We apply the proposed design method of the reset controller to the van der Pol equation and show its effectiveness.