Switched Reluctance Generator Research Articles

Wind-Driven Position Sensorless Switched Reluctance Generator and Diesel Generator Based Microgrid for Optimal Fuel Consumption and Power Blackout Mitigation

This paper proposes a battery-supported wind power generation system (WPGS) with a mechanical position sensorless switched reluctance generator (SRG) and a diesel generator set (DGS) to enable uninterrupted electricity to remote locations. A sliding mode position observer (SMPO) estimates the SRG speed and position based on the generator voltages and currents. The proposed control approach enhances the consideration of dynamic variations in demand and generation in light of the potential for off-grid operation of small-scale WPGS in regions with a weak or nonexistent grid. Diesel engines perform best at 80%-100% of full capacity. At this mechanical loading, CO and other greenhouse gases are the lowest. The proposed approach keeps the DGS at 80%-100% loading regardless of mechanical load to maximize efficiency. In such a microgrid, the power quality (PQ) concern is dominant due to the use of local nonlinear loads. Hence, a joint logarithmic hyperbolic cosine adaptive filter (JLHCAF) is designed for the microgrid to mitigate the PQ issues emerging due to the nonlinear loads.

Fuzzy Super-Twisting Sliding Mode Controller for Switched Reluctance Wind Power Generator in Low-Voltage DC Microgrid Applications

There is limited research focused on achieving optimal torque control performance of Switched Reluctance Generators (SRGs). The majority of existing studies tend to favor voltage or power control strategies. However, a significant drawback of SRGs is their susceptibility to high torque ripple. In power generation systems, torque ripple implicates fluctuations in the generated power of the generator. Moreover, high torque ripple can lead to mechanical vibrations and noise in the powertrain, impacting the overall system performance. In this paper, a Torque Sharing Function (TSF) with Indirect Instantaneous Torque Control (IITC) for SRG applied to Wind Energy Conversion Systems (WECS) is proposed to minimize torque ripple. The proposed method adjusts the shared reference torque function between the phases based on instantaneous torque, rather than the existing TSF methods formulated with a mathematical expression. Additionally, this paper introduces an innovative speed control scheme for SRG drive using a Fuzzy Super-Twisting Sliding Mode Command (FSTSMC) method. Notably robust against parameter uncertainties and payload disturbances, the proposed scheme ensures finite-time convergence even in the presence of external disturbances, while effectively reducing chattering. To assess the effectiveness of the proposed methods, comprehensive comparisons are made with traditional control techniques, including Proportional–Integral (PI), Integral Sliding Mode Control (ISMC), and Super-Twisting Sliding Mode Control (STSMC). The simulation results, obtained using MATLAB®/SIMULINK® under various speeds and mechanical torque conditions, demonstrate the superior performance and robustness of the proposed approaches. This study presents a thorough experimental analysis of a 250 W four-phase 8/6 SRG. The generator was connected to a DC resistive load, and the analysis focuses on assessing its performance and operational characteristics across different rotational speeds. The primary objective is to validate and confirm the efficacy of the SRG under varying conditions.

An Incorporated Power and Data Synchronous Transmission Method for SRG Integrated Wind Power Generation Systems

Reliable communication places important roles in renewable generation for operating status monitoring, fault alarming, cooperative control and so on. For existing power and data synchronous transmission strategies applied to switched reluctance generator (SRG) systems, the communication rate is limited by very low power switching frequencies. Hence, in this paper, a new PDST strategy is proposed and implemented in an SRG integrated wind generation system by incorporating power and data composite modulation method with signal injection method. For lower signal band, the data is modulated together with power by regulating the lower power switch of each phase in a fixed interval with given frequency, and for the higher signal band, the data in form of voltage ripple is injected into the bus by a coupling circuit. Therefore, specific voltage ripples with different given frequencies can be embedded into the power line for carrying signals, and the frequency band of signal bus can be well exploited. On signal receiver end, the voltage ripples are sampled and analyzed by fast Fourier transform method for demodulating the transmitted data. The feasibility of the proposed incorporated data transmission method is verified by experimental testing.

A Review “The Research Status of Switched Reluctance Generator"

Switched Reluctance Generators (SRGs) have become quite popular lately because they offer some big advantages compared to regular generator technologies. This comprehensive review paper is dedicated to illuminating the latest developments in the realm of SRGs, offering a deep dive into their operational intricacies, diverse types, design principles, control strategies, versatile applications, and the formidable challenges that lay ahead. The paper begins by explaining in simple terms how Switched Reluctance Generators (SRGs) work and uncovering the main ideas that make them special and different from other generators. It then proceeds to categorize SRGs into various types, providing an insight into the diverse design features that distinguish them. This foundational understanding sets the stage for a more profound exploration of SRGs. The review focuses significantly on studying the complex control methods that manage SRGs, exploring the advanced techniques used to make them work better and more efficiently. As SRGs continue to evolve, their applicability spans a broad spectrum, ranging from clean energy generation to enhancing transportation systems and powering industrial machinery. This review carefully explains how SRGs can help change many different industries for the better. It shows how they have a lot of potential to make big improvements. Nevertheless, SRGs do not come without their share of challenges, encompassing issues related to efficiency, reliability, and the complexities inherent in control strategies. This review serves as an informative exploration of SRGs, highlighting their potential across various industries. It acknowledges their development and urges them to keep exploring their promising abilities. As switched reluctance generators become more popular, this discussion provides a detailed guide for those interested in understanding how they work and navigating their complex features.

Novel proposal of PTO direct-drive linear generator, an Azimuthal Multi-translator Switched Reluctance Machine (AMSRM): mechanical, characterization and performance tests.

Research and development on power take-off (PTO) in wave energy has been gaining relevance in recent years, appearing as a priority in various forums (JCR reports [1], SRIA in wave energy development [2], specific research funding program in WES, etc.).
 The new proposal of a linear electric generator to act as a PTO in wave energy extraction applications has been developed in the European project SEATITAN [3].
 The linear generator is based on a switched reluctance machine type topology in which the magnetic flux is azimuthal. This allows eliminating the yoke, reducing the amount of magnetized material needed and increasing the force density, besides having a cylindrical shape that allows adapting perfectly to the spar of point absorber type WECs.
 The Azimuthal Multi-translator Switched Reluctance Machine (AMSRM) has been developed, designed and a prototype has been manufactured in the project. The prototype is composed of two modules of 35 kN of force and 3 m/s of peak velocity.
 The complete manuscript will detail the testing facility, as well as the tests performed for the static characterization of the force, electrical losses, and air gap achieved during manufacturing, as well as the dynamic characterization of frictional losses and a preliminary setting of force control parameters.
 The dry test facility (figure 1) consists of the necessary electronic converters to conveniently operate the generator and impose a reference force controlling current per generator coil. In addition, an end-stopper is provided to ensure the safety of the tests (this equipment is essential for dynamic tests). For static tests, a load cell for force measurement as well as precision electrical power meters are used.
 
 A test protocol has been defined for each test, as well as an analysis procedure to obtain the required results: for example, for the evaluation of friction, dynamic tests based on a back-and-forth motion with drifting sections are proposed to evaluate the braking force with the generator off at various speeds.
 The description of the test protocol, the raw data obtained, the data analysis carried out, and de results obtained will be presented and detailed in the manuscript, as well as the description of the test-based parameterization of a simplified AMSRM model to be used in the dynamic modeling of WECs. The simplified model has been previously developed and presented in EWTEC 2021.
 [1] D. Magagna, R. Monfardini, and A. Uihlein, “JRC Ocean Energy Status Report 2016 Edition,” 2016
 [2] J. L. Villate et al., “Strategic Research and Innovation Agenda for Ocean Energy,” Etipocean, no. 826033, p. 64, 2020.
 [3] WEDGE GLOBAL, “SeaTitan,” 2018. [Online]. Available: https://seatitan.eu/. [Accessed: 29-Nov-2021].
 [4] Marcos Blanco, Miguel Santos‐Herran, Gustavo Navarro, Jorge Jesus Torres, Jorge Najera, and Luis García-Tabarés, “Simplified model of a novel direct-drive PTO based on an azimuthal linear switched reluctance generator,” 2021.

Improving Efficiency and Power Output of Switched Reluctance Generators through Optimum Operating Parameters

The optimization of energy production in renewable energy systems is crucial to improve energy efficiency. In this context, the aim of this study focuses on maximizing the efficiency of a switched reluctance generator. This paper presents a novel approach to enhance the electrical power and efficiency of a switched reluctance generator by determining the optimal operating parameters based on the mechanical input power of the system. The proposed strategy consists of the following steps: First, an algorithm was developed that provides machine data for different power modes based on control parameters, including electrical and mechanical powers such as speed, torque, and turn-on and turn-off angles. In the next step, the obtained data were analyzed to identify the optimum points corresponding to the states with maximum power and efficiency for various scenarios. An algorithm for maximum power point tracking was also developed to determine the optimal parameters as a function of mechanical energy. Finally, the data and algorithms were integrated into the switched reluctance generator control system. Simulations were conducted to compare the proposed MPPT technique with other techniques. This comparison is essential to validate the effectiveness of the proposed strategy in achieving enhanced electrical power generation efficiency.

Improvement of Fault Ride-Through Capability of Grid Connected Wind Turbine Based on a Switched Reluctance Generator Using a Dynamic Voltage Restorer

This paper presents an improvement to the fault ride-through (FRT) capabilities for a wind turbine that employs a switched reluctance generator (SRG) using a dynamic voltage restorer (DVR). The wind turbine may be disconnected from the grid by voltage sag, swell, and faulty line voltage in the grid. To improve the stator voltage of an SRG during grid failures, the DVR is applied to inject voltage at the point of common coupling (PCC) into the grid voltage. A control strategy for the DVR based on fuzzy logic controller (FLC) is proposed in this study to improve the FRT capability and meet the grid codes while avoiding the disconnection of the turbine from the grid. MATLAB/SIMULINK simulation validated the effectiveness and performance of this approach under three test cases: balanced sag, unbalanced sag, and a single line-to-ground fault. In addition, the total harmonic distortions utilizing different controllers were compared in sag mode. Furthermore, the simulation results exhibited significant improvement in transient and steady-state response, thus verifying the effectiveness of the control strategy compared to traditional methods.

Calculation of Losses in the Magnetic Circuit of a High-Speed Switched Reluctance Generator

Calculation of Losses in the Magnetic Circuit of a High-Speed Switched Reluctance Generator

Direct average torque control of switched reluctance generator

AbstractThere are few pieces of research on switched reluctance generator (SRG) that accomplish optimal performance torque control, most prefer to use voltage, speed, or power control strategies. This paper proposes a direct average torque control (DATC) for SRG applied to wind energy conversion systems (WECS). The SRG is driven by an asymmetric half‐bridge converter (AHB), and an external chopper regulates the DC‐bus voltage. In the DATC strategy, the switching logic is modified, so that the machine operates in the generator mode. The dynamic behavior of an artificial neural network (ANN)‐based and the conventional co‐energy‐based torque estimation methods are discussed. Thereafter, the proposed DATC is compared to the direct power control (DPC) strategy. For both strategies, lookup tables are created to store the optimal switching angles. These lookup tables are optimized to achieve a trade‐off between torque ripple minimization and efficiency maximization. Experimental results show that the DATC strategy presents a lower torque ripple than the DPC method over the entire speed range. In contrast, DPC delivers superior efficiency for low and medium speeds.

Bipolar power converter and control of switched reluctance generator system for renewable energy storage

PurposeBecause of the shortage of energy, the development of green and reliable energy is particularly important. As a green and clean energy, wind power is widely used. As the core component of wind power generation, it is particularly important to choose generators with high reliability. Switched reluctance machine is widely used as generators because of its strong fault tolerance and high reliability. Therefore, this paper aims to propose a power converter and its control strategy to improve the efficiency of switched reluctance generators.Design/methodology/approachIn this paper, a full-bridge power converter (FBPC) instead of the asymmetric half-bridge power converter (AHBPC) is adopted to drive the switched reluctance generator (SRG) system. Compare the FBPC with the AHBPC, the FBPC has several advantages including low cost and modularization, and operation process of SRG winding current direction is variable.FindingsThe results show that the SRG system can keep smooth operation by the FBPC with relatively high efficiency.Originality/valueThe FBPC is suitable to drive the SRG system. Meanwhile, this paper introduces two excitation modes of the FBPC as three-phase three-beat mode and six-phase six-beat mode. When the six-phase six-beat control strategy is adopted, the dead band time of the converter can be avoided. At the same time, the SRG has higher efficiency.

Reliability evaluation on SRG with full-bridge power converter considering thermal stress

PurposeQuantitative reliability analysis can effectively identify the time the driving system needs to be maintained. Then, the potential safety problems can be found, and some catastrophic failures can be effectively prevented. Therefore, this paper aims to evaluate the reliability of the switched reluctance generator (SRG) driving system.Design/methodology/approachIn this paper, a method considering different thermal stresses and fault tolerance capacity is proposed to analyze the reliability of an SRG. A full-bridge power converter (FBPC) instead of the asymmetric half-bridge power converter (AHBPC) is adopted to drive the SRG system. First, the primary fault modes of the SRG system are introduced, and a fault criterion is proposed to determine whether the system fails. Second, the thermal circuit model of the converter is established to quickly and accurately obtain the junction temperature of the devices. At last, the Markov models of different levels are established to evaluate the reliability of the system.FindingsThe results show that the two-level Markov model is the most suitable when compared to the static model and the one-level Markov model.Originality/valueThe driving system of SRG will be more reliable after the reliability of the system is evaluated by the Markov model. At the same time, an FBPC is adopted to drive the SRG. The FBPCs have the advantages of fewer switching devices, higher integration and lower cost. The proposed driving strategy of the FBPC avoids the current reversal and the generation of dead zone time, which has the advantage of reliable operation. In addition, a precise thermal circuit model of the FBPC is proposed, and the junction temperature of each device can be obtained, respectively.

Meta Heuristic Optimization Algorithm based Rectifier Control in Switched Reluctance Generator

A simple, robust, economical and highly efficient 8/6 switched reluctance (SR) generator is connected to a wind turbine to increase the amount of power extracted from the wind. Output power of the generator is fed to the PWM rectifier via a four-phase asymmetric half-bridge (AHB) converter and maximum power point tracking (MPPT) of the rectifier is assisted with torque ripple minimization to present an effective control as it allows torque ripple suppression arising from the SR generator nature while capturing maximum wind power. The wide range of speed variation of the SR generator is minimized using the combination of PI and hysteresis current controller. Further, the output of the AHB converter is directed to the conventional PWM rectifier. The purpose of this research is to deliver ripple-free dc power to a dc grid/load or battery. Hence, in this paper, the GWO-based optimized PI controller is implemented as an MPPT method to maintain the constant dc bus voltage. The inherent ability of GWO optimization-based control of the rectifier system ensures better dynamic control. The simulation is performed in a MATLAB environment for a power rating of 1000W standalone system and tested using an FPGA controller. This paper carries out a stability analysis of the system by varying the wind velocity.

Design and analysis of underwater power generation characteristics of deflected double-stator switched reluctance generator

The Deflectable double-stator Switched Reluctance Generator (DSRG) has the advantages of simple structure, small volume and multi-dimensional operation. The DSRG and propeller are combined into the application of underwater power generation. With the help of the deflect ability of the generator, the efficiency is improved. Due to the uncertainty of ocean current direction and the structure of switched reluctance generator, the torque ripple is one of the important factors damaging the underwater generator. In order to effectively suppress the influence of torque ripple caused by generator operation, a method of adding pole shoes on the pole side of outer stator is proposed, so as to reduce the torque ripple. The propulsion structure running at different deflection angles is simulated. The torque and speed obtained before and after pole shoe optimization are input into the propeller model. The pressure and speed characteristics of the corresponding blade structure are simulated to verify the effect of optimization and the effectiveness of the power generation system.

Multi-Objective Control Strategy for Switched Reluctance Generators in Small-Scale Wind Power Generations

Switched reluctance generators (SRGs) are widely used in wind power generation. However, due to the natural tendency of SRG, there are always nonnegligible conflicts to achieve high efficiency and low output voltage ripple at the same time. This creates difficulties for the high-performance of SRG. Thus, a multi-objective optimization control strategy is proposed in this paper to improve the static performance of SRG. The proposed control strategy contains following steps. First, in order to gain the maximum output power range at different rotor speeds, the turn-off angle is optimized off-line by simulated annealing algorithm (SAA). The optimized results are fitted as a function of rotor speed for on-line regulating; then, a closed-loop controller is built, and the reference current is regulated according to the difference between actual output power and required output power. Second, a multi-objective function is constructed as the evaluation result of SRG performance, which takes system efficiency, output voltage ripple and power converter loss into consideration. In the end, the turn-on angle is tuned by SAA according to the real-time multi-objective evaluation result. The proposed control strategy can be flexibly applied to SRGs with different structures and avoids the disadvantage of single-objective optimization. The simulation and experiments results show that the overall performance of SRG is improved.

Phase Current Reconstruction Technique for Four-Phase Switched Reluctance Generator With Two Current Sensors

The paper proposes a novel current reconstruction technique with two current sensors to reconstruct the phase currents in a 4-phase switched reluctance generator (SRG). Conventionally with the asymmetric half-bridge converter (AHB), four current sensors are employed, one in each phase for measuring the phase currents in SRG. In the proposed work, the AHB converter’s DC bus is split into the excitation bus and the generating bus. Two current sensors are employed, first in the excitation bus, measuring the energization current of the respective active phase during phase excitation. And the second current sensor is placed in the generating bus, measuring the generating current. The switching functions of the AHB converter are re-designed such that the phase current during free-wheeling and de-energization flows through the generating bus. The proposed current reconstruction technique using linear algebraic equations facilitates the reconstruction of phase currents from two current sensors only. This is the first time a paper experimentally verifies the proposed phase current reconstruction technique for 4-phase SRG, wherein multiple phases are conducting simultaneously. Also, during power electronics switch fault the proposed current reconstruction method successfully reconstructs healthy phase currents after isolating the faulty phase.

Wind SRG-Based Bipolar DC Microgrid with Grid-Connected and Plug-In Energy Supporting Functions

Although a switched reluctance generator (SRG) is not the mainstream wind generator, it possesses the application potential and is worth developing for its many structural merits and high developed power ability. This paper presents a wind SRG-based bipolar DC microgrid having grid-connected and plug-in energy supporting functions. First, a surface-mounted permanent magnet synchronous motor (SPMSM)-driven wind turbine emulator (WTE) is established. Next, the wind SRG with an asymmetric bridge converter is developed. Good generating characteristics are obtained through proper designs of power circuit, commutation mechanism, external excitation source, voltage and current controllers. Third, a DC/DC boost interface converter and a bipolar voltage balancer are constructed to establish the 500 V microgrid bipolar DC-bus. To preserve the microgrid power supplying quality, a battery energy storage system (BESS) with bidirectional DC/DC interface converter is equipped. A dump load leg is added across the bus to limit the DC-bus voltage under energy surplus condition. In load side, a three-phase bidirectional load inverter is developed, which can be operated as a single-phase three-wire (1P3W) inverter or a three-phase three-wire (3P3W) inverter. Good sinusoidal voltage waveform and regulation characteristics are obtained using the proportional-resonant (PR) control. The microgrid to load and microgrid to grid operations are conductible. Finally, to further improve the powering reliability of microgrid, a three-phase T-type Vienna switch-mode rectifier (SMR) based plug-in energy supporting scheme is developed. When the microgrid energy shortage occurs, the possible harvested energy can be used to supply the microgrid.

Electromechanical dynamic analysis for powertrain of off-grid switched-reluctance wind turbine hydrogen production system

Research on hydrogen production from wind power is important for improving wind energy utilization and hydrogen production efficiency; however, research on switched-reluctance hydrogen production from wind power has been relatively limited, and its system operation characteristics are unclear. Therefore, it is necessary to conduct research on the electromechanical coupling characteristics of switched-reluctance wind turbine hydrogen production systems (WTHPSs). An electromechanical dynamic model was established for the powertrain of an off-grid switched-reluctance WTHPS, including wind turbine, gear transmission system, switched-reluctance generator (SRG), and hydrogen production devices (HPDs). The model considers the detailed characteristics of the gear system, the nonlinear physical details of the HPD, and the electromagnetic characteristics of the generator. An improved control strategy was also developed for the SRG to reduce torque fluctuation. The steady- and transient-state electromechanical characteristics were simulated and analyzed, and the influences of the SRG control strategy and HPD switching on the system dynamic characteristics and hydrogen production rate were investigated. First, with respect to the improved SRG control strategy, the results show that SRG torque fluctuation can be reduced. The influence of the SRG electromagnetic torque on the transmission system gradually decreases from the high-speed stage to the low-speed stage. However, for a sudden decrease in wind speed, the SRG with the improved control strategy tracks the reference speed more slowly. Second, with respect to the hydrogen production rate, almost no difference can be observed between the two SRG control strategies. Single and multiple HPDs have a slight effect on the dynamic characteristics of the system when the HPDs can consume all the generated power. The production rate of HPDs in a parallel connection is higher than that with a single device at the same power, and the difference increases with an increase in power.

Maximum Power Control and Optimization of Switched Reluctance Generators for Wind Turbines

In this paper, a maximum power control and optimization of a 4-phase 8/6-pole Switched Reluctance Generator (SRG) are realized for a wind energy conversion system by using MATLAB/Simulink. Unlike conventional generators, using of the SRGs has increased in variable speed wind turbines due to important advantages such as lower copper losses, simple structure, flexible control, and a good performance in a wide speed range. However, since SRGs work with switching logic, their torque production is fluctuating and optimum turn-on/turn-off angles of the phases must be determined to work as a generator. Therefore, in this study, these angles are optimized based on the speed of the SRG and Maximum Power Point Tracking (MPPT) is realized. Besides, a voltage control is provided by keeping the DC bus voltage at the output of the system constant at the desired value with the help of a chopper controlled unloader. The results obtained from the optimized model for variable wind speed conditions are compared with that of the unoptimized model. It is observed that the SRGs can work more stable with a proper optimization method and the power obtained from the system follows the maximum output power.

Analysis of Maximizing the Power Output of Switched Reluctance Generator Using Different Core Materials

Switched reluctance generator (SRG) has become the key focus of research for its usage in wind power generation. The sizing and performance of SRG depend on the core material used for the stator and rotor. This paper analyses the impact of the magnetic loading of different core materials on the performance of SRG in terms of self-inductance, torque, iron losses, ohmic losses, and generated voltage. 1 kW SRG with different pole configuration 8/6 SRG and 12/8 SRG for the wind speed of 3 m/s to 6 m/s has been designed. Static and dynamic analyses using the finite element analysis (FEA) were carried out for analytically designed 1 kW SRG with different core materials with the same lamination thickness. Prototypes of 8/6 SRG and 12/8 SRG are fabricated. The output of simulation results has been validated by experimental measurements.

Optimal Control of Single-Pulse-Operated Switched Reluctance Generator to Minimize RMS Phase and RMS DC-Bus Current

Optimal Control of Single-Pulse-Operated Switched Reluctance Generator to Minimize RMS Phase and RMS DC-Bus Current