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This paper proposes a fault-tolerant control (FTC) strategy using the current space vectors to diagnose sensor failures and enhance the sustained operation of a field-oriented (FO) controlled induction motor drive (IMD). Three space vectors are established for the sensor fault diagnosis technique, including one converted from the measured currents and the other two calculated from the current estimation technique, respectively, measured and with reference speeds. A mixed mathematical model using three space vectors and their components is proposed to accurately determine the fault condition of each sensor in the motor drive. After determining the operating status of each sensor, if the sensor signal is in good condition, the feedback signal to the controller will be the measured signal; otherwise, the estimated signal will be used instead of the failed signal. Failure states of the various sensors were simulated to check the effectiveness of the proposed technique in the Matlab/Simulink environment. The simulation results are positive: the IMD system applying the proposed FTC technique accurately detected the failed sensor and maintained stability during the operation.

Although the asynchronous machine is renowned for its qualities of robustness, reliability, low cost of construction and efficiency, it happens nevertheless that faulty operations may appear during its lifetime. Numerous papers have studied the mechanical defects detection in electric motors using stator currents. The present paper is focused on the detection of load unbalance in three-phase induction motor relying on stator currents analysis. The proposed approach is based on the analysis of current space vector transformation, which takes in consideration all the information provided by the induction machine, this information is analysed by the means of Power Spectral Density and the Wavelet Packet Decomposition techniques. For this purpose, an experimental setup is designed to conduct experimental tests and show the advantages of space vector transformation compared to single-phase analysis. The obtained results are discussed and analysed.

Power electronic converters are used for an efficient and controlled conversion of power generated from renewable energy sources and can interface generated power to the grid. Among available power converters, voltage source inverters (VSIs) have been widely employed for grid-connected applications due to better controllability with higher efficiency. Although various conventional, as well as modern control techniques, have been developed for grid connected VSI system, there is a need to select suitable control technique based on application and control requirements. Hardware-in-the-loop (HIL) is considered as a realistic approach for the development of system and control due to the inclusion of an actual hardware system. In this paper, a HIL approach is adopted for the comprehensive analysis and development of a grid connected VSI system using a field programmable gate array (FPGA). The control techniques must deal with trade-off, based on the features and limitations. Therefore, a grid-connected VSI system is developed considering employment of two different conventional control techniques: hysteresis current control (HCC) and PI-based space vector modulation (PI-SVM), as well as finite state model predictive control (FS-MPC) as a modern control technique for investigation considering different parameters. All three control systems are developed through a digital simulator of Xilinx that is integrated with MATLAB-Simulink, while considering an FPGA based system development and testing through FPGA HIL co-simulation methodology.

This paper presents a novel soft switching topology and its control method applied on three-phase current source inverter. The main switch transistors of the inverter can be achieved in soft switching on the current pass-through step, which can reduce switch stress and improve efficiency. The soft switching circuit consists of two auxiliary switch transistors and some passive devices, such as inductor, capacitor and diode. It has many advantages as follows, simple control, fewer devices, high reliability, and so on. This paper analyzes the principle of soft switching circuit, and simulate by using the current space vector control method with MATLAB. The simulation results demonstrate the feasibility of the method.

This study introduces a fast locating algorithm for a switched shunt capacitor based on the slopes of the voltage/current space vectors at monitoring points of a power system. Compared with the other suggested slope-based methods, such as signal-processing and filter-based methods, the proposed algorithm herein offers a robuster and more reliable locating method because of using the information of all three phases, whereas other methods separately process individual phase signals. The method is training free and established based on algebraic calculations with a simple realisation algorithm, which is independent of the power system dynamics and parameters. The proposed method is analytically investigated and then verified based on the time-domain simulation of two study systems. The study systems cover various capacitor-switching scenarios, harmonic effects and measurement noise and power system dynamics including dynamics of rotating machines and power electronic converters.

Space vector control Simulink model is developed and investigated. Physical phenomena occurring in AC motor during mentioned control usage and results are discussed. Short circuit mode is investigated. Article in Lithuanian. Srovės erdvinio vektoriaus valdymo modelis Santrauka. Straipsnyje nagrinėjamas vektorinis asinchroninio variklio valdymas, maitinant asinchroninį variklį iš srovės inverterio. Sukurtas asinchroninio variklio dinaminis modelis MatLab SIMULINK terpėje. Modelis papildytas erdvinio srovės vektoriaus valdymo blokais ir taip sudarytas kompleksinis vektorinio valdymo pavaros modelis. Pateikiama asinchroninio variklio netiesioginio srovės erdvinio vektoriaus valdymo struktūrinė schema, pagal kurią sudarytas dinaminis modelis. Pateikiamos tiriamojo variklio dinaminės charakteristikos reverso metu, kai prieš antrąjį reversą trumpai sujungiamos dvi maitinimo apvijos. Aptariami gauti trumpojo jungimo imitacijos rezultatai. Reikšminiai žodžiai: srovės erdvinis vektorius, valdymas, asinchroninis variklis, modelis.

Parallel multilevel inverter becoming a very attractive structure for medium- and high-power/voltage applications. This is mainly due to the fact that it can achieve high-power level and overcome voltage /current limitations of switching devices. However due to the differences in hardware parameters, the circulating current appears in this structure and degrades its performance. This paper presents a circulating current control method for paralleled three-level neutral point clamped (NPC) inverter. The analytical model that describes the circulating current generation and behaviors is demonstrated, and then using this model, a control method to eliminate the circulating current is proposed. The proposed strategy is realized by introducing a control variable adjusting the application times of the redundant vectors of the three-level space vector modulation (SVPWM). In addition, a PI-controller based on closed loop control is synthetized to determine automatically the appropriate adjustable duration, during which the redundant vectors will be applied to eliminate the circulating current among the paralleled inverter. Finally, the effectiveness of the proposed circulating current control method under different operating conditions is confirmed through experimental validation.

Permanent magnet synchronous motors are used in various high-performance applications with many control algorithms, each of which has its advantages and disadvantages. One of the most widely used control methods for this motor type is the Field-Oriented Control. Associated with a space vector modulation-controlled inverter, this approach has numerous advantages, including its rapid current and torque response and fixed switching frequency. The most used regulator for this control method is the PI regulator. However, this regulator exhibits an overshoot that may negatively affect the whole control loop. The IP structure can theoretically solve this problem without any further computation. This study presents an experimental comparison between the PI and the IP structures of linear controllers in a vector-controlled permanent magnet synchronous motor (PMSM) drive with space vector modulation. The results show that the IP regulator significantly reduces the overshoot compared to the PI regulator while effectively dampening load disturbances. The experimental results also show that the IP regulator exerts minimal current demand during motor start-up, minimising perturbations. Additionally, the direct current remains close to the reference value with both regulators, despite the greater initial perturbations in the PI regulator. These findings highlight the IP structure’s superiority in mitigating overshoot and enhancing the overall performance of the vector-controlled PMSM drive. This study provides new insights into the advantages and limitations of the PI and IP. The observed reduction in overshoot and the disturbance rejection capabilities of the IP regulator demonstrate its potential to enhance the control loop stability and overall system performance.

This paper presents a current source inverter (CSI) with zero-voltage-switching (ZVS) for low-input voltage PMSM application. And its working principle, space vector modulation (SVM) method, high-frequency switching process are analyzed in detail. The detailed ZVS realization conditions are also designed. The proposed circuit is consisted of a high-gain buck-boost chopper circuit, a three-phase bridge and a C filter, it has the advantage of a wide output voltage range. The proposed modulation method realizes SVM control due to the optimized energy storage mode. The proposed soft-switching scheme realizes the ZVS of the energy storage switch by designing the resonance parameters and controlling the turn-on time of the active clamp circuit. The feasibility and advancement of the proposed CSI drive system are verified by 24VDC/1 kW prototype experiments.

This review article is mainly oriented to the control and applications of modular multilevel converters (MMC). The main topologies of the switching modules are presented, for normal operation and for the elimination of DC faults. Methods to keep the capacitor voltage balanced are included. The voltage and current modulators, that are the most internal loops of control, are detailed. Voltage control and current control schemes are included which regulate DC link voltage and reactive power. The cases of unbalanced and distorted networks are analyzed, and schemes are proposed so that MMC contribute to improve the quality of the grid in these situations. The main applications in high voltage direct current (HVDC) transmission along with other medium voltage (MV) and low voltage (LV) applications are included. Finally, the application to offshore wind farms is specifically analyzed.