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Modeling uncertainties in DC-DC converters with MAtLab® and PLECS®
(2018-11-07)
Asadi, Farzin
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Pongswatd, Sawai
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Eguchi, Kei
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Trung, Ngo Lam
Modeling is the process of formulating a mathematical description of the system. A model, no matter how detailed, is never a completely accurate representation of a real physical system. A mathematical model is always just an approximation of the true, physical reality of the system dynamics. Uncertainty refers to the differences or errors between model and real systems and whatever methodology is used to present these errors will be called an uncertainty model. Successful robust control-system design would depend on, to a certain extent, an appropriate description of the perturbation considered. Modeling the uncertainties in the switch mode DC-DC converters is an important step in designing robust controllers. This book studies different techniques which can be used to extract the uncertain model of DC-DC converters. Once the uncertain model is extracted, robust control techniques such as H<inf>1</inf> and µ synthesis can be used to design the robust controller. The book composed of two case studies. The first one is a buck converter and the second one is a Zeta converter. MATLAB® programming is used extensively throughout the book. Some sections use PLECS® as well. This book is intended to be guide for both academicians and practicing engineers.
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Particle swarm optimization based specified order robust-gap H∞ loop shaping controller design
(2017-01-01)
Konghuayrob, Poom
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Kaitwanividvilai, Somyot
The demand of data storage capacity in hard disk drive is expected to increase significantly which the areal density will achieve 10 Tbit/in2 in the near future. An increase of high areal density leads to the reduction of distance per data tracks. Due to the narrow track pitch, hard disk drive system is easily sensitive to the disturbance and noise. This is the benchmark problem for controlling the high precision servo mechanism. The alternative robust loop shaping based v-gap metric is proposed to synthesize the optimal controller for stabilizing a voice coil motor in hard disk drive servo system. Additionally, the designed loop shaping is evaluated by the Riccati procedure with regard to the system robustness. This paper applies the potential particle swarm optimization (PSO) to minimize the close loop gap between the loop shaping of the plant with weighting function and the plant with proposed controller. Moreover, the structure of proposed controller can be specified as the 2nd order controller which is uncomplicated to implement in the actual application. The simulation illustrates similar results in terms of the performance tracking and disturbance rejection of proposed controller against the H<inf>∞</inf> loop shaping. Furthermore, the system stability index called stability margin with 0.434 emphasizes the robustness of the proposed controller.
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Adaptive PID for controlling a quadrotor in a virtual outdoor scenario: Simulation study
(2013-11-25)
Moonumca, Pisan
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Yamamoto, Yoshio
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Depaiwa, Nattawoot
The main purpose of this paper is to develop a robust control methodology for unmanned aerial vehicles such as a quadrotor. A conventional proportional-integral-derivative (PID) controller is augmented with adaptive K<inf>P</inf> or non-adaptive K<inf>P</inf> in a throttle input and the both cases are compared and analyzed. Adaptive K<inf>P</inf> is suitable for a system which is subjected to parameter uncertainty, such as variation in payload or wind speed, as the algorithm is able to adjust the K<inf>P</inf> gain of the PID controller so that they maintain robustness and performance. The performance results of the two controllers when applied to a quadrotor are demonstrated using numerical simulation. © 2013 IEEE.
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Specified structure mixed H2=H∞ control-based robust frequency stabilization in a smart grid by plug-in hybrid electric vehicles
(2013-01-16)
Ngamroo, Issarachai
In the future smart grid, the penetration of wind power tends to increase significantly. This may cause the tie-line power and frequency fluctuations in the power grid. On the other hand, the plug-in hybrid electric vehicles (PHEV) are highly expected to be installed in the customer side. The bidirectional power control of PHEV can be applied to stabilize the power and frequency fluctuations. This paper proposes the specified structure mixed H<inf>2</inf>=H<inf>∞</inf> control design of bidirectional power controller of PHEV for robust frequency stabilization of the smart grid with large wind farms. System uncertainties are represented by the multiplicative perturbation model. The structure of power controller is specified as a proportional integral (PI) with single input. The PI parameters optimization problem is formulated based on the enhancement of control performance and robustness against system uncertainties. Without the difficulty of weighting functions selection as in a mixed H<inf>2</inf>=H<inf>∞</inf> control, the PI parameters are automatically tuned by particle swarm optimization. Simulation results confirm that the proposed robust controller is much superior to the conventional controller in terms of control performance and robustness against various uncertainties. © 2013 ICIC International.
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Robust coordinated control of electrolyzer and PSS for stabilization of microgrid based on PID-based mixed H 2/H ∞ control
(2012-09-01)
Ngamroo, Issarachai
In the stand-alone microgrid with hybrid wind, fuel cell (FC) with electrolyzer (EZ) and diesel generations, the intermittent wind power may cause the serious power fluctuation. In addition to the hydrogen production for FC, the EZ can be used to alleviate power fluctuation by an appropriate control of the absorbed power. Nevertheless, the EZ may fail to suppress the power fluctuation due to large disturbances. To enhance the EZ control performance, a power system stabilizer (PSS) which is assumed to be equipped with a diesel generator can be used. This paper proposes the robust coordinated control of EZ and PSS for microgrid stabilization. The structure of power controller of EZ and PSS is a proportional-integral-derivative (PID). To improve the damping performance and robustness of EZ controller and PSS, the PID parameters of both EZ and PSS are simultaneously tuned based on the mixed H <inf>2</inf>/H <inf>∞</inf> control by bee colony optimization. Simulation studies show that the stabilizing performance and robustness of the proposed EZ and PSS are superior to those of the individual device under system uncertainties such as various wind patterns, loading conditions and severe faults. © 2012 Elsevier Ltd.
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Design and implementation of a high performance Hard Disk Drive servo controller using GA based 2DOF robust controller
(2012-02-01)
Kaitwanidvilai, Somyot
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Nath, Amar
Currently, HDD (Hard Disk Drive) with VCM actuator covers more than 80% of the HDD market. To enhance the capacity and ability of the system, a new class of servo controller is required to achieve both the robustness and performance of the entire system. This paper proposes a new technique for designing a robust controller for HDD with Voice Coil motor (VCM) actuator; the control design problem, H <inf>∞</inf> loop shaping with structured controller, is solved by Genetic Algorithm (GA). The proposed technique does not only solve the problem of high order controller in the conventional design, but also still retains the robust performance of conventional H <inf>∞</inf> control technique. In addition, structured pre-filter in the 2DOF control scheme is also designed by GA to enhance the performance in terms of time-domain tracking. Simulation and experimental results verify the effectiveness of our proposed technique. © 2012 ICIC International.
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PMU-based system identification for wide area robust PSS design in interconnected power systems with wind farm
(2012-01-01)
Ngamroo, Issarachai
It is well known that the penetration of wind power in the smart power grids not only causes the power fluctuation problem, but also results in the system instability. To tackle this problem, a sophisticated design of robust power system stabilizer (PSS) based on system identification using multiple synchronized phasor measurement units (PMUs) is proposed. The small load fluctuation is applied to the system in order to generate the phasor data measured from multiple PMUs which are assumed to be located in the system. Applying the least square method, the phasor data are used to identify the coupled vibration model (CVM) which represents the dominant inter-area oscillation modes. The CVM is used to design the PSS which is a 2nd-order lead-lag compensator. To take system uncertainties such as variation of system parameters etc., in the CVM, the inverse additive perturbation model is applied. Based on an enhancement of the robust stability margin and damping effect, the PSS parameters optimization problem is formulated. The genetic algorithm is used to solve the problem and achieve the PSS parameters. The performance and robustness of the proposed PSS are evaluated in the IEEJ Western Japan 10 machine power system with wind farm in comparison with a conventional PSS. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.
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Robust control design for three-phase power inverters using genetic algorithm
(2012-01-01)
Nimpitiwan, Natthaphob
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Kaitwanidvilai, Somyot
This paper proposes a new technique to design a fixed-structure robust controller for grid connected three-phase inverter systems. The proposed technique applies the Genetic Algorithm to evaluate the optimal controller parameters. The integral squared error (ISE) of the controlled system is minimized and the robust performance (RP) of the system is satisfied. In the proposed design, the structure of controller is specified as a decentralized Proportional-Integral (PI) controller which is preferred for practical implementations. Simulation results show that the proposed technique is promising. Applying the proposed technique ensures wide operating conditions for three-phase power inverters.
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Simultaneous optimization of SMES coil size and control parameters for robust power system stabilization
(2011-06-01)
Ngamroo, Issarachai
As the coil size is the heart of superconducting magnetic energy storage (SMES), the simultaneous optimization of coil size and control parameters of SMES for robust power system stabilization is proposed. The structure of active and reactive power controllers of SMES is the practical first-order lead/lag compensator. To handle system uncertainties such as various generating and loading conditions, unpredictable network structures etc., the multiplicative uncertainty model is embedded in the system modeling. As a result, the optimization problem of SMES coil size and controller parameters based on the enhancement of system damping and robust stability margin against system uncertainties can be formulated. Solving the problem by a particle swarm optimization, both optimal coil size and controller parameters are obtained simultaneously and automatically. Simulation study in the West Japan six-area interconnected power system with two SMES units confirms the superior robustness and damping performance of the proposed SMES controller with an optimal coil size under various situations in comparison with the conventional SMES controller. © 2011 IEEE.
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Robust controller design of heat pump and plug-in hybrid electric vehicle for frequency control in a smart microgrid based on specified-structure mixed H2/H∞ control technique
(2011-01-01)
Vachirasricirikul, Sitthidet
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Ngamroo, Issarachai
This paper proposes a new robust controller design of heat pump (HP) and plug-in hybrid electric vehicle (PHEV) for frequency control in a smart microgrid (MG) system with wind farm. The intermittent power generation from wind farm causes severe frequency fluctuation in the MG. To alleviate frequency fluctuation, the smart control of power consumption of HP and the power charging of PHEV in the customer side can be performed. The controller structure of HP and PHEV is a proportional integral derivative (PID) with single input. To enhance the performance and robustness against system uncertainties of the designed controller, the particle swarm optimization based-mixed H<inf>2</inf>/H<inf>∞</inf> control is applied to design the PID controllers of HP and PHEV. Simulation studies confirm the superior robustness and frequency control effect of the proposed HP and PHEV controllers in comparison to the conventional controller. © 2011.

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