Control
Fatemeh Tavakkoli; Alireza Khosravi; Pouria Sarhadi
Abstract
This work represents a new method for robustness analysis of the model reference adaptive controller (MRAC) in the presence of input saturation. Saturation is one of the nonlinear factors affecting the stability of control systems which must be considered in controller design and stability analysis experiments. ...
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This work represents a new method for robustness analysis of the model reference adaptive controller (MRAC) in the presence of input saturation. Saturation is one of the nonlinear factors affecting the stability of control systems which must be considered in controller design and stability analysis experiments. Various methods are presented for the stability and robustness analysis of adaptive control systems, and employment of describing function (DF) can be attractive and practical, due to the appropriate effectiveness of DF in estimating limit cycles and also the application of quasi-linearization theory. In this work, the stability analysis and a limit cycle estimation of a saturated system in the frequency domain is performed. The controller parameters are adjusted in a way that the system achieves its stable limit cycle in the presence of the initial conditions for the states. Moreover, the efficiency of the proposed method for second-order systems is reported in the presence of symmetric saturation and uncertainty model in Rohrs counterexample as the unmodeled dynamics. The results demonstrate the proposed method provides a proper analysis of system stability during the changes in the control parameters and the saturation amplitude.
Electronics
Ata Ollah Mirzaei; Amir Musa Abazari; Hadi Tavakkoli
Abstract
Nowadays, the planar spiral coils are widely used in different applications. Mutual inductance of two adjacent coils, is one of the critical operating principles in near field wireless power and data transmission systems, significantly impacting their performance. Hence, in this study, the mutual ...
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Nowadays, the planar spiral coils are widely used in different applications. Mutual inductance of two adjacent coils, is one of the critical operating principles in near field wireless power and data transmission systems, significantly impacting their performance. Hence, in this study, the mutual inductance between two similar concentric planar spiral coils are investigated. The effect of main parameters, including the track width, w, and the space between two consecutive turns, s, with a fixed inner and outer diameter of the coils are investigated. The Taguchi method using L16 array in Minitab environment is used to optimize design parameters. The samples of applied Taguchi, are modeled and simulated via ANSYS Maxwell. The results show that the mutual inductance increases by reducing the two investigated parameters (i.e., w and s). Based on the Taguchi analysis, it is revealed that the effect of the response for both of the investigated parameters is very close. With applying the main effect analysis the obtained results are verified. This interesting result is important in design of planar spiral coils while we have fabrication limitations in a real sensor design realization.
Power
Reza Rostaminia; Mehdi Vakilian; Keyvan Firouzi
Abstract
Partial Discharge (PD) measurement is one of the best solution for condition assessment of Gas Insulated Switchgears (GIS). For having Condition-based maintenance of GIS, online PD monitoring is in great importance. For this aim, Ultra High Frequency (UHF) PD sensors should be installed inside the GIS ...
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Partial Discharge (PD) measurement is one of the best solution for condition assessment of Gas Insulated Switchgears (GIS). For having Condition-based maintenance of GIS, online PD monitoring is in great importance. For this aim, Ultra High Frequency (UHF) PD sensors should be installed inside the GIS during the installation. However, in most installed GIS in industries, the internal UHF PD sensors are not installed. In this paper, a new method for on-line defect type recognition according to external UHF PD sensors and based on time-frequency representation of PD signal is proposed. In this case four artificial defect type named protrusion on main conductor, protrusion on enclosure, free moving metal particle and metal particle on spacer are implanted inside the 132 kV L-Shaped structure of one phase in enclosure GIS. The signal energy at each level of decomposed signal by Discrete Wavelet Transform (DWT) is applied for features of each defect type. The trends of signal energy variations at each frequency ranges of signal are applied for discriminating between each defect type. The Deep Feed Forward Network (DFFN) classifier is applied for PD pattern recognition. The results show the beneficial and simplicity of the proposed method for PD signal classification, independent from position of PD sensor, especially in case of online PD monitoring of GIS.
Electronics
Hamidreza Ghorbani; Jose Luis Romeral Martinez
Abstract
A new active gate drive for Silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) is proposed in this paper. The SiC MOSFET as an attractive replacement for insulated gate bipolar transistor (IGBT) has been regarded in many high power density converters. The proposed ...
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A new active gate drive for Silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) is proposed in this paper. The SiC MOSFET as an attractive replacement for insulated gate bipolar transistor (IGBT) has been regarded in many high power density converters. The proposed driver is based on a feedforward control method. This simple analog gate driver (GD) improves switching transient with minimum undesirable effect on the efficiency. This paper involves the entire switching condition (turn on/off), and the GD is applied to the SiC base technology of MOSFET. To evaluate the performance of the proposed GD, it will be compared with a conventional gate driver. The presented GD is validated by experimental tests. All the evaluations are carried out in a hard switching condition and at high-frequency operation.
Power
Asaad Shemshadi; Mohammad Reza Khojaste
Abstract
One type of electrical breakdown in solid insulation is electromechanical failure. In mineral processing, crushing rocks is energy intensive. Rock crushing using high voltage has many advantages, including high stone breaking efficiency, and is a new and efficient way to break stone. The shape of the ...
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One type of electrical breakdown in solid insulation is electromechanical failure. In mineral processing, crushing rocks is energy intensive. Rock crushing using high voltage has many advantages, including high stone breaking efficiency, and is a new and efficient way to break stone. The shape of the electrode, the amount of applied voltage, and the selection of drilling process parameters are the main obstacles to using this method. In this study, based on the equivalent circuit of high voltage electro pulse failure, a mathematical model of high voltage electro pulse discharge in rock has been developed. Then, a high-voltage simulation model is developed based on the coaxial cylindrical electrode structure. This paper investigates the use of electromechanical failure phenomena for crushing minerals. High voltage pulses are used to crush the rock, then by simulating the relevant circuit, the necessary voltage for crushing three minerals is obtained and the feasibility of using this method is discussed. Finally, using the simulation and the obtained results, the possibility of using this method for crushing minerals has been investigated. This study provides a scientific basis for quantifying and predicting rock crushing using high-voltage technology in order to improve drilling efficiency and reduce energy loss.