نشریه مهندسی برق و مهندسی کامپیوتر ایران
سال بیستم شماره 4 (پیاپی 74، زمستان 1401)

The simple and accurate design of the flux weighting coefficient for the predictive current control (PCC) algorithm is an important issue that can be seen in all predictive controllers. It should be said that predictive current control is a promising method to obtain fast torque response with a simple and flexible structure, but its development to multi-phase drives can lead to dissatisfaction. In this article, due to the challenge of computing load of PCC algorithm, the weighting coefficient removal method is used and finally modified predictive current control (VV-PCC) without weighting coefficient is used for six-phase induction motor drive. Different operating conditions such as startup, sudden loading and different speeds have been investigated. As a result, choosing a switching state in PCC leads to high x-y currents, this problem requires a small number of repetitions with the proposed VV-PCC method based on removing the weighting factor, because the number of switching states has increased from 49 to 13, and finally It will reduce copper losses and improve power quality. The results and validation of the mentioned cases are presented using MATLAB software.

Fault detection and tolerable control of wind turbine increases its reliability and availability. One of the electrical components of the wind turbine with a high error rate is the power converter. In this paper, a new method for fault tolerant (FT) control of the wind turbine back-to-back converter based on Dual Feed Induction Generator (DFIG) is presented. When a open circuit fault occurs in each of the IGBTs of the wind turbine converter, the performance of the converter is distorted and part of the current signal of each leg of the converter is lost. The classical controller cannot completely correct this change in current behavior, and for this reason, it has an abnormal performance. As a result, power generation will be accompanied by many fluctuations. In order to compensate, a new method based on sliding mode control is presented in this article. First, when an error occurs, the fault detection system identifies the faulty leg, and after reconfiguring the hardware, the proposed control system based on sliding mode control replaces the classic control system and switching operation. The fault detection method presented in this article is based on artificial neural network and it was developed based on matching with the functional parameters of the wind turbine. The proposed FT method is evaluated using a hardware simulator in a laboratory loop with a 90 kW DFIG generator. The experimental results show the proper accuracy of the fault detection method and on the other hand, the proposed FT method was able to compensate the open circuit fault of the IGBT.

Today, in many control methods, neighboring system information is used for better control and synchronization between different units, and therefore, in the access and transmission of information through communication links, problems such as disruption, uncertainty, noise, delay, and cyber-attacks occur. In this paper, the effect of the Denial of Service (DoS) cyber-attack on the microgrid in island mode is investigated and a cooperative distributed hierarchical controller is designed with the presence of this cyber-attack. Distributed Generations (DGs) have been analyzed with the help of multi-agent systems and the communication network between them using graph theory. The effects of the DoS cyber-attack on the model of DGs are mathematically formulated and in proving the stability and synchronization of frequency and voltage, the suitable Lyapunov function is presented and the stability analysis of DGs against these cyber-attacks is performed and the stability and synchronization conditions of DGs are proved. To confirm the proposed theoretical issues, a case study model is simulated despite the DoS attack on the communicative links in Matlab Simulink, and the results show the performance of the designed controller in different conditions.

In this paper, one hybrid analytical model (HAM) based on winding function theory (WFT) was presented for cage-rotor induction motors (CRIMs), which helps from the magnetic equivalent circuit (MEC) for considering the effect of slots and magnetic saturation in stator and rotor cores. A non-linear MEC model is used to calculate the magneto motive force (MMF) drops in iron parts of stator and rotor for every operating point under the healthy condition and broken-rotor bar (BRB) fault. The distribution of MMF drop in stator and rotor is separately expressed in terms of the distribution of equivalent virtual currents and the virtual winding function. The inductances are then calculated using WFT while considering the effect of slots and magnetic saturation. To model the starting of no-load CRIM, the system of electrical and mechanical differential equations is solved using the finite difference method (FDM) under the healthy condition and BRB fault. Hague's solution and one simple conformal mapping (CM) are used to calculate and analysis of air-gap magnetic field. To verify the proposed model, some analytical results are compared with the corresponding results obtained through finite element method (FEM).

Unfalsified adaptive control is a new approach in supervisory control that ensures the selection of a stabilizing controller from a control set based on the system input-output data. A prerequisite for ensuring stability is the existence of a pre-designed controller set that contains a stabilizing controller. The supervisor selects the controller based on the cost function calculated with the system input-output data. In this method, the control system performance is restricted to the controllers of the control set. In this paper, the controller set update is performed by introducing the concept of performance falsification along with the stability falsification of the active controller. To falsify the performance of the controller set, the structure of the model reference is proposed to evaluate the performance of the control system. In case of performance falsification, a new controller is designed and added to the controller set based on system data and without using any model. To design the controller, a linear matrix inequality problem is solved. In this paper, no system model is used, and the presented method is completely model-free and data-oriented. The simulation results show the performance improvement of the proposed method compared to other methods in a standard robust adaptive benchmark system.

In this paper a new topology of pulsed-power converter to generate high-voltage pulses by low-input source is proposed. The proposed high step-up converter can generate high output voltage with few number of elements and stages. This converter which is based on switch-capacitor structure is self-balanced and can be used in portable pulsed power supply. To show the validity of the proposed converter operation, a prototype of the proposed topology in the laboratory was constructed. The results show proper operation of the converter.

In this paper, a compact wideband microwave filter in X band using substrate integrated waveguide technology is designed, simulated and implemented. At first, the structure of hexagonal and semi-hexagonal microwave resonators is studied and their resonate modes, resonance frequencies and field distribution inside these resonators are investigated. Then, a second order Chebyshev filter is designed by coupling matrix of two semi-hexagonal cavities with center frequency of 10 GHz and fractional bandwidth of 20%. The first designed filter based on theoretical modeling is simulated by a full wave simulator and the geometrical parameters of the structure are adjusted for the required response. A prototype of the designed filter is implemented by TLY031 substrate and its characteristics are successfully measured. The results show that the measured results agree well with those obtained by simulation. The center frequency of the implemented filter is 8.7 GHz and it provides 27.3% bandwidth, with maximum insertion loss of 2.1 dB.