Positioning and Smoothing Movement Approaches of a Linear Actuator Dedicated to A Biomedical Application

The movement of linear stepper motors is characterized by a highly oscillatory translation, which is troublesome for the positional accuracy and the speed constant (often required by many industrial applications such as the syringe pump). These oscillations can lead to loss of synchronism and stall risk. Thus, in order to attenuate the amplitudes of these oscillations and to guarantee the positioning of the actuator without errors, solutions exploiting open-loop and closed-loop control techniques are proposed in this paper for the purpose of improve the performance of the actuato

Geometric Parameter Optimization of Switched Reluctance Machines for Renewable Energy Applications using Finite Element Analysis

The choice of SRM design depends on the specific application and performance requirements. Factors such as power output, torque characteristics, and efficiency will all influence the choice of SRM design. To find an optimal geometry, it is therefore necessary to determine the effect of each parameter such as rotor pole angle, stator pole angle, stator external diameter, rotor diameter, air gap length, rotor yoke, stator yoke and shaft diameter on the machine performance. For this reason, this paper discusses a comparative study of the geometric parameters influence on SRM performance. The analysis is performed by finite element simulations based on the variation of rotor inclination, air gap length, stator and rotor polar arc variations of three machine topologies such as the three-phase 12/8 SRM, three-phase 6/4 SRM and four-phase 8/6 SRM. For a reliable comparison, these machines must have the same basic dimensions (stator outer diameter, rotor outer diameter and length) and operate in the same magnetic circuit saturation. Graphical and numerical results of torque and magnetic flux for three SRM topologies are highlighted. The presented study aims to provide reliable results on the dimensions to be adjusted for various applications

Software in-the-Loop Simulation of an Advanced SVM Technique for 2ϕ-Inverter Control Fed a TPIM as Wind Turbine Emulator

An appropriate modulation scheme selection ensures inverter performance. Thus, space vector modulation (SVM) is more efficient and has its own distinct advantages compared to other pulse width modulation (PWM) techniques. This work deals with the development of an advanced space vector pulse width modulation (SVM) technique for two-phase inverter control using an XSG library to ensure rapid prototyping of the controller FPGA implementation. The proposed architecture is applied digitally and in real time to drive a two-phase induction motor (TPIM) for small-scale wind turbine emulation (WTE) profiles in laboratories with minimum current ripple and torque oscillation. Four space voltage vectors generated for the used SVM technique do not contain a zero vector. Hence, for an adequate adjustment of these four vectors, a reference voltage vector located in the square locus is determined. Considering the asymmetry between the main and auxiliary windings, the TPIM behavior, which is fed through the advanced SVM controlled-two-phase inverter (2ϕ-inverter), is studied, allowing us to control the speed and the torque under different conditions for wind turbine emulation. Several quantities, such as electromagnetic torque, rotor fluxes, stator currents and speed, are analyzed. To validate the obtained results using both Simulink and XSG interfaces, the static and dynamic characteristics of the WTE are satisfactorily reproduced. The collected speed and torque errors between the reference and actual waveforms show low rates, proving emulator controller effectiveness

A Comprehensive Review on Space Vector Based-PWM Techniques for Common Mode Voltage Mitigation in Photovoltaic Multi-Level Inverters

Nowadays, transformer-less photovoltaic (PV) multi-level inverters (MLIs) are commonly employed in both industrial and residential settings. This structure has attracted increased attention due to its unique advantages, such as higher efficiency, lower cost and size, better waveform quality, and inherent fault tolerance. However, due to the removal of the transformer, the common mode voltage (CMV) becomes one of the crucial issues in transformer-less PV MLIs. The high-frequency variation in CMV results in a leakage current that deteriorates the line current quality, increases the PV power system losses, leads to severe electromagnetic emissions (EMI), reduces the PV array lifespan, and causes personal safety problems. In this regard, this paper presents a review of the existing and recent research on modulation techniques based on space vector pulse width modulation (SVPWMs) that overcome this issue in transformer-less three-level NPC-MLIs (3L-NPC-MLIs). The reduced CMV-SVPWM (RCMV-SVPWM) can be mainly categorized as an RCMV-SVPWM based on the vector type, based on virtual vectors, and based on the two-level SVPWM (2L-SVPWM). Their features and their limitations in terms of several main criteria are discussed. In the final section of this paper, some challenges and future trends for this research area are projected

IM Fed by Three-Level Inverter under DTC Strategy Combined with Sliding Mode Theory

The classical direct torque control (CDTC) of the induction motor (IM) drive is characterized by high ripples in the stator flux and the electromagnetic torque waveforms due to the use of hysteresis comparators. Furthermore, the motor speed in this control strategy is ensured through a proportional integral (PI) regulator, due to its simple structure. Nonetheless, this controller is sensitive to load disturbances. Hence, it is not robust against parameter variance, which can degrade the motor performance. To overcome this deficiency, many endeavors have been conducted in the literature to ensure a high dynamic response of the motor in all speed ranges, with minimum flux and torque undulations. Thus, the DTC of an IM associated with a three-level inverter based on sliding mode (SM) flux, torque and speed controllers was adopted to substitute the hysteresis comparators and the traditional PI regulator, since the SM speed controller is able to prevail against external disturbances. The second contribution of this manuscript is to develop the proposed DTC_SM approach using the Xilinx System Generator (XSG) in order to implement it on a field programmable gate array (FPGA) Virtex 5 on account of its ability to adopt parallel processing. The hardware co-simulation results verify clearly the merits of the suggested modified DTC strategy

Improvement of the Iraqi Super Grid Performance Using HVDC/HVAC Links by the Integration of Large-Scale Renewable Energy Sources

The increasing use of renewable energy sources (RES) and their integration into transmission systems requires extensive studies to get more benefits from these sources. Stability analysis is one of the most crucial issues in these systems, and therefore needs to be studied in depth. In this paper, an analytical study was conducted for the stability assessment of the Iraqi super grid after adding a solar power plant with a capacity of 1000 MW using both HVAC and HVDC links for comparison purposes. Thus, the objective of this study was to determine the best way to integrate RES into the power grid while improving its performance. The system’s stability was evaluated for two types of faults: line and bus disturbances. The strength of the grid and its ability to absorb the newly added energy was also studied. The simulations were performed with the PSS/E software using the Newton-Raphson method for a 500 km transmission line length. The results showed that the HVDC link outperforms the HVAC link in improving the overall performance of the power system

Integration of Switched Reluctance Generator in a Wind Energy Conversion System: An Overview of the State of the Art and Challenges

This paper presents a technical overview for Switched Reluctance Generators (SRG) in Wind Energy Conversion System (WECS) applications. Several topics are discussed, such as the main structures and topologies for SRG converters in WECS, and the optimization control methods to improve the operational efficiency of SRGs in wind power generation systems. A comprehensive overview including the main characteristics of each SRG converter topology and control techniques were discussed. The analysis presented can also serve as a foundation for more advanced versions of SRG control techniques, providing a necessary basis to spur more and, above all, motivate the younger researchers to study magnetless electric machines, and pave the way for higher growth of wind generators based on SRGs

Improvement of Steady State Performance of Voltage Control in Switched Reluctance Generator: Experimental Validation

This paper presents a voltage control approach to a Switched Reluctance Generator (SRG) using a Proportional Integral (PI) controller. The principle of operation is described and the considerations in the design of controller are discussed. A current loop transfer function of an SRG with power converter has been systematically derived in order to obtain a small-signal model for the generator. The generated voltage is controlled by manipulation of the setpoint of the current control of the generator. The entire voltage loop controller and current control have been simulated and tested with a 250 W SRG prototype. The control law of the control system was implemented on a digital signal processor (TMS320F28379D). To verify the feasibility of the proposed voltage control, the performances are evaluated by numerical simulations and experimental tests with an 8/6 SRG for different rotational speeds and resistive loads. Experimental results demonstrate that the DC output voltage from SRG can be controlled well using a simple linear controller

Improvement of Steady State Performance of Voltage Control in Switched Reluctance Generator: Experimental Validation

This paper presents a voltage control approach to a Switched Reluctance Generator (SRG) using a Proportional Integral (PI) controller. The principle of operation is described and the considerations in the design of controller are discussed. A current loop transfer function of an SRG with power converter has been systematically derived in order to obtain a small-signal model for the generator. The generated voltage is controlled by manipulation of the setpoint of the current control of the generator. The entire voltage loop controller and current control have been simulated and tested with a 250 W SRG prototype. The control law of the control system was implemented on a digital signal processor (TMS320F28379D). To verify the feasibility of the proposed voltage control, the performances are evaluated by numerical simulations and experimental tests with an 8/6 SRG for different rotational speeds and resistive loads. Experimental results demonstrate that the DC output voltage from SRG can be controlled well using a simple linear controller

Light chain nephropathy

Light chain deposition disease (LCDD) is characterized by the tissue deposition of monotypic immunoglobulin light chains of either kappa or lambda isotype. It is the archetypal systemic disease that is most frequently diagnosed on a kidney biopsy, although the deposits may involve several other organs. This brief review focuses on the clinicopathological features of LCDD-associated nephropathy with an emphasis on the diagnostic and therapeutic difficulties related to this elusive condition