Switched Reluctance Generator Research Articles

Active Source Current Filtering to Minimize the DC-Link Capacitor in Switched Reluctance Drives

Switched reluctance machines receive increased attention from the automotive industry because of their cost efficiency. However, the independent phase excitation and the resulting current reversal demand comparatively large dc-link capacitors to meet the requirements regarding the ripple on the dc-link voltage and current. This paper validates the effects of the usage of a dc-dc boost converter to reduce the size of the dc-link capacitor by actively filtering the source current. The active filter is compared with the state-of-the-art topology and a passive filter. The investigations show that the active filter is able to reduce the dc-link capacitance by 80%. The dc-dc converter also provides the feature of adjusting the inverter dc-link voltage level independently from the battery voltage level. The positive effect of this additional degree of freedom on the machine efficiency is investigated and due to this feature the total efficiency of the electrical drive train remains nearly unchanged despite the extra losses in the dc-dc converter. All presented results are based on detailed simulations and experimentally validated with a 20 kW switched reluctance generator.

A New Control Strategy for SR Generation System Based on Modified PT Control

The Switched Reluctance generator (SRG) has been widely used as a constant voltage source due to its advantages of simple structure, low cost and high control flexibility. However, the output voltage ripples cannot be ignored due to its unique operating principle with phase commutation. In this paper, the influence of the control parameters on the output voltage ripples are analyzed, and a fly-wheeling pulse train (FW-PT) control strategy is proposed to suppress the voltage ripple. The output voltage can be regulated by the FW-PT control strategy by using two or more sets of preset control pulse combinations, therefore it has the advantages of simple circuit implementation, no Network compensation and fast response speed. The characteristics of steady-state and dynamic behaviors of the switched reluctance power generation system by using different control strategies are simulated and compared, and a platform of 200W 8/6 SRG is built for experimental verification. Simulation and experimental results confirm that compared with the traditional PID control strategy, the FW-PT control strategy can be used to not only suppress the output voltage ripple, but also achieve faster response and dynamic characteristics.

Проектирование и выбор параметров вентильно-индукторного генератора

Проектирование и выбор параметров вентильно-индукторного генератора

Development and Operation Control of a Switched-Reluctance Motor Driven Flywheel

This paper presents the development of a switched-reluctance machine (SRM) driven flywheel system, its charging/discharging controls, and performance evaluations. By properly setting and tuning the winding commutation instant, the same SRM can be operated as a motor and a generator in the SRM-driven flywheel system with satisfactory performances. Moreover, the hysteresis current controlled pulsewidth modulation scheme with hard freewheeling and the commutation angle dynamic shift controller are proposed to enhance the flywheel discharging generating performance. For interfacing the flywheel system to the dc microgrid, a half-bridge bidirectional dc-dc interface converter is developed. It is operated in a buck mode under flywheel charging and in a boost mode under flywheel discharging. The dynamic modeling and controller design are conducted to yield well-regulated dc output voltage under varying flywheel-driven switched-reluctance generator (SRG) speed. Finally, the measured results are given to verify the performances of the established flywheel and its interconnected operation to a wind SRG-based dc microgrid.

Optimization of Output Voltage of Switched Reluctance Generator Based on Improved Fuzzy Control

This paper takes the output of the switched reluctance generator as the research object and analyzes the main factors affecting the output voltage ripple. In order to optimize the output voltage of the switched reluctance generator at high speed, This paper proposes an angle position control strategy based on improved fuzzy control. When the load changes, the initial value of the turn-on angle of the fuzzy control adjustment is adaptively identified. Adaptive value of turn-off angle input to the system. This method quickly and accurately changes the conduction angle so that the output voltage is optimized. The simulation results show that compared with the fuzzy control, the improved fuzzy control strategy can effectively optimize the output voltage and reduce the voltage ripple.

Synthesis of Fuzzy Setpoint for Control System of Switched Reluctance Generator

Synthesis of Fuzzy Setpoint for Control System of Switched Reluctance Generator

Passivity-Based Control of Switched Reluctance-Based Wind System Supplying Constant Power Load

This paper presents a passivity-based control (PBC) scheme for the switched reluctance generator (SRG) in small-scale wind energy conversion systems for dc microgrid applications. The main objective is to stabilize the output voltage in case the system supplies constant power loads (CPLs) and operates with maximum power point tracking (MPPT). Stability improvement and dc-link ripple reduction in the presence of CPLs is achieved using system-level modeling of SRG-based dc microgrid through the Euler-Lagrange system (ELS) from the viewpoint of the machine physical structure. Compared with other control methods, the proposed MPPT method based on passivity-based speed controller employs the back electromotive force (EMF) in the generation process as a position-dependent voltage source to overcome the major challenge of SRG complicated uncertain dynamic model. To deal with the time-varying inductance and back EMF of SRG, an adaptation mechanism is incorporated in the proposed adaptive PBC and the control design is constructed by using the Lyapunov theorem where the closed-loop stability is ensured. The effectiveness of the proposed method in avoiding instability effects of SRG and CPL with voltage ripple reduction and precise wind turbine speed tracking is investigated with simulation results and validated with experimental by using a four-phase, 8/6 SRG drive system.

Complementary power generation of double linear switched reluctance generators for wave power exploitation

The wave power generation system based on the single linear generator scheme has low energy output and week robustness, especially in low speed conditions and parameter variations. To overcome the problem, a scheme of complementary power compensation generation for two asymmetric bilateral linear switched reluctance generators (ABLSRGs) is proposed in this paper. Mathematic model is first derived and machine characteristics are investigated by the finite element method. The compensation scheme is carefully investigated together with the independent control method. Under the conditions of parameter and velocity variations, experimentation demonstrates that both the voltage control accuracy and system robustness can be guaranteed with the proposed complementary power generation control scheme. Experiment results show that a voltage control precision of 11.75–12.23 V can be obtained, with the voltage reference of 12 V.

Design and Research of Double-Sided Linear Switched Reluctance Generator for Wave Energy Conversion

As a clean and renewable energy source, wave energy is of great significance in solving primary energy shortages and environmental pollution. Direct-drive wave power systems consisting of linear generators have attracted the attention of researchers from various countries. Linear Switched Reluctance Generator has the advantages of simple structure, sturdiness, reliable operation, suitable for harsh environments, and easy maintenance, aiming at the problem of single-sided magnetic pull force and serious coupling of phase winding of traditional linear switched reluctance generator, a Double-sided Linear Switched Reluctance Generator (DLSRG) for wave power generation is designed, and its electromagnetic characteristics (including coupling characteristics, magnetic saturation characteristics, and magnetic tension characteristics) are analyzed to verify the rationality of the structure and parameter selection. Finally, the power generation performance is studied. The joint simulation results show that the structure design of DLSRG is reasonable, overcomes the problem of single-sided magnetic pull force, the phase-to-phase coupling is negligible, and it has continuous power generation capability, and the power generation efficiency is as high as 80.6%. Therefore, DLSRG designed in this paper is suitable for wave power generation.

Enhanced radial fuzzy wavelet neural network with sliding mode control for a switched reluctance wind turbine distributed generation system

ABSTRACTIn this article, an Enhanced Radial Fuzzy Wavelet Neural Network with Sliding Mode (RFWNNSM) and hill-climb searching (HCS) maximum power point tracking (MPPT) strategy are proposed for a switched reluctance generator (SRG) in a variable-speed wind energy conversion system (WECS). The implemented MPPT control is an HCS algorithm that does not require the knowledge of turbine or generator characteristics. However, this study proposes a simple optimal DC-Link voltage search type HCS control, and therefore a faster convergence to MPPT is achieved. A high-performance online training Enhanced Radial Fuzzy Wavelet Neural Network (RFWNN) using a back-propagation learning algorithm with a sliding mode regulating controller is designed for an SRG. The MPPT strategy locates the system operation points along the maximum power curves based on the DC-Link voltage of the inverter, thus avoiding the need to detect the generator speed.

Maximum Power Point Tracking for a Point Absorber Device with a Tubular Linear Switched Reluctance Generator

This paper addresses the control of a Tubular Linear Switched Reluctance Generator (TLSRG) with application in a point absorber device. A maximum power point tracking (MPPT) strategy is proposed to maximize the power extraction from ocean waves. The generator is characterized by average maximum force of 120 kN and a maximum velocity of 1.3 m/s. The proposed MPPT is achieved by changing the generator damping load according to the excitation force induced by a regular wave. A hysteresis controller is applied to regulate the phase current intensity which allows the control of the linear force provided by the generator. The conversion system direct current (DC) bus voltage is adjusted by an isolated DC/DC converter with a proportional integral controller to define the appropriate duty-cycle.

Improvement of the Response Speed for Switched Reluctance Generation System Based on Modified PT Control

The Switched Reluctance Generator (SRG) is suitable for wind power generation due to its good reliability and robustness. However, The SRG system adopting the conventional control algorithm with Pulse Width Modulation (PWM) method has a drawback, low response speed. The pulse train (PT) control has been widely used in dc/dc power converters operating in the discontinuous conduction mode due to its advantages of simple implementation and fast response. In this paper, for the first time, the PT control method is modified and adopted for controlling the output voltage of SRG system in order to achieve fast response. The capacitor current on the output side is sampled and combined with the output voltage to select the pulse trains and the low frequency oscillation cased by PT can be suppressed by tuning the feedback coefficient of the capacitor current. Also, good performance can be guaranteed with a wide range of voltage regulations, fast response, and no overshoot. The experimental platform of an 8/6 SRG system is built, and the experimental results show that the PT control can be used for SRG system with good practicability.

Investigation of a Switched Reluctance Generator Using the Voltage Pulse Width Modulation Method

An analytical modeling method of the current for a Switched Reluctance Generator (SRG) using voltage Pulse Width Modulation (PWM) control is proposed. The current equation is achieved from the inductance model in combination with the voltage equation. The proposed inductance model is divided into four regions which depend on the pole arcs of the rotor and stator and the inductance at aligned and unaligned positions. A method to obtain a PWM duty cycle and the optimal turn-on and turn-off angles of the SRG undervoltage PWM control is presented. An SRG with 8 stator poles and 6 rotor poles was setup to validate the proposed method. The PWM duty cycle and optimal control variables based on the proposed method were used to control the SRG. The results indicated that the SRG could generate the optimum phase current over a wide speed range.

Dynamic Performance Analysis of a Switched Reluctance Generator 6x4 for Wind Energy Application

Dynamic Performance Analysis of a Switched Reluctance Generator 6x4 for Wind Energy Application

Design of Computational Experiment for Performance Optimization of a Switched Reluctance Generator in Wind Systems

This paper presents as a new contribution a proposal to optimize the performance of a switched reluctance generator (SRG) in a variable wind energy conversion system. An approach based on the design of computational experiment is applied to determinate the optimal firing angles and the optimal dc link voltage that guarantee the best system behavior for each rotor speed. A third-order response surface model based on space-filling designs is applied to build a multiobjective function considering efficiency improvement and torque ripple reduction. An interior point method is applied to find the minimum of the surface, optimizing the process. Direct power control is used to obtain the maximum power as a function of the rotor speed, employing the optimal parameters. Hysteresis and single-pulse current control are applied for low- and high-speed operation, respectively. Simulation and experimental results have shown that the proposed approach returned a good compromise between SRG high efficiency and low torque ripple. Moreover, the presented technique reduces computational effort and provides a clear massive data simulation framework.

Theoretical analysis and simulation of single-winding bearingless switched reluctance generator with wider rotor teeth

The bearingless switched reluctance machine with wider rotor teeth (BSRMWR) can achieve decoupled control of suspension and torque in the starter/generator system. This article makes theoretical analysis and simulations of generation mode in 12/8 single-winding BSRMWR. First, the generation and suspension principles of single-winding bearingless switched reluctance generator (BSRGWR) are explained; Second, the levitation force model of BSRGWR is derived based on the Maxwell stress tensor method. Then a suspension control scheme is proposed to eliminate the coupling of levitation forces in X and Y directions. This article also discusses the reasons why the generation currents of one phase should be controlled symmetrically. Finally, the calculation of different control variables are summarized in a flow chart. Then the open- and closed-loop controls of single-winding BSRGWR are also included to justify that the generator can work normally.

Sensorless control of wind SRG in dc microgrid application

This paper presents an innovative and effective control strategy of Switched Reluctance Generator (SRG), operating with Vujicic-Calasan PCT1 power converter in continuous-conduction mode (CCM), for a wind energy conversion system (WECS) employed in DC microgrids. The Vujicic-Calasan PCT1 power converter, whose validity in this paper is additionally confirmed through simulations and experimental results, is based on diode bridge rectifiers and does not contain switch components. Namely, it requires four diodes and one inductance filter per machine phases as well as one excitation voltage source. By regulating the dc excitation voltage the output power of SRG can be easily controlled. A procedure for determination of the optimal excitation voltage as a function of rotor speed, that provides maximal output power for defined RMS phase current and voltage is proposed. Moreover, the obtained optimal dependences are mathematically described to be used for control of SRG in WECS. In the simulations performed to study the proposed control strategy, a realistic wind profile is used, while the turbine operation with and without pitch controller is considered. Simulations results provided for the WECS confirm that the proposed control strategy ensures system stability and fast maximal power point tracking.

Improved current control scheme with online current distribution and DFA regulation for switched reluctance generator

In this study, an improved phase current control scheme (CCS) for switched reluctance generator is developed and evaluated. The objective of proposed CCS is to find the most efficient operating point according to output power command directly and shorten the online tuning process. The CCS is augmented with an online phase current distributing block (OCDB) and a dynamic firing angle regulator (DFAR). In OCDB, phase current is distributed online to minimise copper loss by maximising the average-torque–ampere ratio. In DFAR, firing angles are processed according to actual phase current and current command. Improvements in current responses by augmenting DFAR are verified by simulations and experiments. In the end, the proposed CCS is employed in an output power controller for practical applications. Experimental results show that the proposed CCS has good dynamic response and finds the most efficient operating point directly.

Developing a Switched-Reluctance Generator for an Autonomous Charge-Discharge Electrical Engineering Facility

A switched-reluctance generator (SRG) of electrical engineering facilities was developed on the basis of the switched-reluctance machine for the new mobile charge-discharge facility for the ship-mounted accumulator batteries. The present SRG meets the Vietnam climate requirements [1]. The possible SRG design variants, as well as the analysis of the generator operation in the two possible electric circuits, that is, with a controlled inverter and with an uncontrolled rectifier at the output, are presented. The impact of the switching parameters on the basic SRG characteristics in different modes is considered. The dependency of control angles variation on the output power and the effective phase current value are presented for the IG-2×550 generator mode.

Accumulator Capacitor Converter for a Switched Reluctance Generator

In this paper, a novel converter is presented to improve the excitation process in switched reluctance generators (SRGs). Accumulator capacitor converter (ACC) is based on a singular scheme of flyback converters. ACC performs two main roles. First, in an initial step, it charges an accumulator capacitor with a determined value of voltage; then, during the magnetizing period, it discharges the stored energy into machine coils. Therefore, ACC provides the SRG with a determined magnetizing energy and uses the forced magnetizing phenomenon to magnetize its coils. The processes yield some outstanding superiority such as excellent operation at high speeds, simple controlling scheme, lower stress on the excitation source, etc., over conventional converters. To analyze the performance of ACC, the required analytical expressions for charging the capacitor and discharging it into the coils are developed and the constraints for switching periods are demonstrated in detail. Afterward, through MATLAB/Simulink and finite-element analysis (FEA) simulations, its operation is evaluated and compared to conventional asymmetric bridge and bifilar converters (BFCs); moreover, its test bed is assembled and tested experimentally, and its results, along with the simulation ones, validates ACC performance.