Two-phase Switched Reluctance Motor Research Articles

Design of Two-Phase Switched Reluctance Motor (SRM) for Two-Wheel Electric Vehicle and Torque-Density Based Comparison With Three-Phase SRM

Design of Two-Phase Switched Reluctance Motor (SRM) for Two-Wheel Electric Vehicle and Torque-Density Based Comparison With Three-Phase SRM

A C-Core Connected Two-Phase Switched Reluctance Motor With Embedded Permanent Magnets for Developed Torque Enhancement

Conventional switched reluctance motors (SRMs) face challenges like low torque density and high noise. To overcome these challenges, the structure of SRMs can be modified. This paper introduces a new hybrid-excited 16/18 two-phase SRM with a C-core structure. Each pole of the C-core has two teeth, which develop a positive torque during the rotor rotation; this enhances the torque and torque density of the motor. To show the merits of the proposed SRM with PMs, its static and dynamic characteristics, including flux density, flux-linkage, and torque, are obtained and compared with the SRM with no PMs, the 8/12 two-phase conventional SRM, and other motors with the same volume; a significant match was achieved. Finally, both proposed SRMs were prototyped and tested. Comparing the simulation and test results elucidates that the proposed SRM with PMs has unique high output power, torque, and efficiency.

Two-phase switched reluctance motor drive control system design

The two-phase switching reluctance motor drive control system uses STM8S003F3 as the control chip to realize the control function. The hardware circuit is mainly composed of switched reluctance motor controller power and relay control circuit based on an asymmetric half-bridge circuit, a drive circuit module based on IR2101S, a rotor detection module based on a photoelectric sensor, current detection and protection circuit based on Hall current sensor, power supply circuit based on the multi-integrated chip. The control system has been significantly improved in safety and reliability.

Design of Two-Phase 4/6 Switched Reluctance Motor for Bidirectional Starting in Washing Machine Application

In this article, design modification of stator poles of conventional two-phase switched reluctance motor is proposed to achieve self-start in both directions of rotation. Stator poles are slanted in a particular direction at the pole tips. This creates a range of rotor positions where torque polarity is the same for both phases, so starting torque is available. A unique excitation scheme is also proposed to run the motor in a particular direction from any initial position. The sequence in which the two phases are excited and the duration of their first excitation decides the direction of continuous rotation. Washing machine is selected as a potential application of the proposed work. Design parameters such as input voltage, rated current, and torque-speed characteristics are investigated to suit top-load washing machines. Simulations are carried out in finite element analysis software. Relation between the slant angle of the stator pole tip and minimum starting torque is analyzed through parametric simulations. Experiments are performed on a prototype two-phase switched reluctance motor. An incremental encoder is used as a position sensor. The initial position is not known, but self-starting in both directions of rotation is achieved with the proposed excitation scheme.

Comprehensive Investigation of an Improved Two-Phase Modular PM-Assisted Switched Reluctance Motor for Enhanced Torque Performance

in order to enhance motor torque performance of existing two-phase 8/10 E-Core SRM, an improved modular permanent magnet (PM)-assisted Switched Reluctance Motor (SRM) structure is presented. Firstly, basic structure and operation principle of the proposed structure are introduced. To further evaluate performance improvement, effects of various parameters on the design such as inductance, flux-linkage, average torque and cogging torque are compressively investigated by finite element method (FEM) software subsequently. In the meantime, comparisons with other two-phase SRM structures are also performed including average torque, torque/PM volume, torque/ motor volume, torque/current, etc. Finally, a prototype is fabricated, and simulation and experimental results verify that the proposed design has high torque performance.

A New Optimization Method for Pole-arc Parameters of Variable-gap Two-phase Switched Reluctance Motor

As a switched reluctance motor with simple structure, a two-phase switched reluctance motor (SRM) has the advantages of the above. In contrast, the complexity of the motor structure and the manufacturing cost are low, and only one-way operation is required. The control strategy is simple. Based on the analysis of the self-starting mechanism of the two-phase switched reluctance motor with variable air-gap rotor structure, the structure scheme of the variable airgap rotor is determined by the finite element method. Two-dimensional model of two-phase switched reluctance motor with vertical air gap structure. To minimize the electromagnetic torque ripple, the structure parameters of the motor such as air gap, stator-rotor pole arc and winding turns are optimized. To solve the finite element optimization simulation time process, a numerical batch interpolation method is developed to optimize the non-uniform pole arc of the rotor to improve the finite element simulation speed. Finally, the fixed-rotor pole arc and winding turns of the motor are optimized. The motor parameters are further optimized to make the static performance of the motor more stable.

Position Estimation of a Two-Phase Switched Reluctance Motor at Standstill

In this paper, a sensorless position detection method of a two-phase switched reluctance motor (SRM) at standstill is proposed based on the voltage pulse injection method. Due to the torque dead zone and the lack of starting capability in the two-phase SRM, a rotor with a stepped structure is adopted to ensure continuous torque generation. The inductance characteristics of the asymmetric SRM are analyzed, and the region of the rotor position is categorized into linear regions and nonlinear regions with several key rotor positions and threshold values of self-inductance. A simple analytical model of the phase self-inductance profile of the asymmetric rotor SRM is proposed, which only requires a few linear equations, to replace the conventional look-up table. A pulse injection-based position estimation method is proposed based on the aforementioned analytical model. Short voltage pulses are injected into both phases at the same time to determine the position where the rotor is actually located at standstill. The proposed position detection method is simple and requires no extra circuitry. The simulation results are given and show the proposed estimation method can acquire a precise rotor position accurately at a standstill condition.

Nonlinear Modeling of a C-Core Connected Two-Phase Switched Reluctance Motor

The main idea of this paper is to offer a continuous C-cores unique configuration for switched reluctance motor (SRM) and to present an analytical model for its analysis. The advantages of this structure are having a short path for the main part of the magnetic flux, resulting in less core losses and as well as less negative torque. On the other hand, there is less leakage flux in the proposed structure. Another advantage of this structure is that it has a high mean torque compared to conventional structures, so that this increase in mean torque also increases a small amount of torque ripple, which is negligible. However, power density at a constant volume increases relatively much. The proposed SRM is analyzed by the finite element method (FEM) and by employing a magnetic flux density pattern and magnetic fluxes path, its magnetic equivalent circuit (MEC) is obtained. In this MEC model, the main fluxes and leakage fluxes are fully modeled. After its complete analysis, electromagnetics torque, inductance, flux-linkage, mean torque, and peak torque are evaluated. Static and dynamic performances are then determined. Finally, the proposed SRM was prototyped and tested. The experimental results consisting of static torque, flux-linkage, voltage, and current waveforms and input power are compared with the corresponding results in the MEC model and FEM. The comparisons verify the accuracy and validity of the introduced analytical model. Besides, static torque, flux-linkage characteristics, and dynamic performance at a nominal speed of 1000 rpm and the current chopping control mode with chopping 5A under the load of the proposed SRM are compared with the conventional SRM and its merits are observed.

A Novel 8/10 Two-Phase Switched Reluctance Motor With Enhanced Performance: Analysis and Experimental Study

A novel 8/10 two-phase switched reluctance motor is proposed. Thanks to this unique design, the flux paths are shortened, resulting in lower magnetomotive force requirements. There is no negative torque, bringing a higher total torque. The space is more effectively utilized to provide a higher torque density. Flux reversals in the iron cores are reduced, causing a significantly lower loss. The associated conceptual diagrams, optimized design procedures, detailed flux study, and loss analysis are presented. The proposed motor is compared with two existing 9/12 and 6/10 switched reluctance motor in terms of topology advantages, peak and average torques, torque density, core losses, etc. Moreover, a new efficiency index is introduced to more reasonably perform comparisons. Furthermore, finite element method is employed in the investigations. Finally, the motor is prototyped whose experimental results including torque-angle measurements and open-loop control confirm the novelty and superiorities of the proposed motor over the existing ones.

A torque control strategy for a two-phase switched reluctance motor based on dynamic ranking of voltage vectors

Switched reluctance motor (SRM) suffers from high torque ripple which limits its application in many areas. In order to improve the control performances of SRM, a novel torque control strategy based on dynamic ranking of voltage vectors is developed in the paper. Multiple voltage vectors are selected as candidates at any control instant to enhance the control flexibility, and they are evaluated by a ranking process to determine their suitability to be finally applied to the power converter. The ranking evolves dynamically based on the prediction of motor output torque change rate, phase torque change rate, current change rate, and flux vector change at the next control instant. Several control rules are developed and finally the scheme is applied to a two-phase SRM. The control performances are analysed in the simulation which shows the validity of the proposed scheme.

Effect of Objective Function Formulation on Static and Operating Parameters of a Switched Reluctance Motor After Optimization of Magnetic Circuit Shape

The article presents a comparison of two optimization methods aimed at the linearization of electromagnetic torque on rotor position angle in a two-phase switched reluctance motor (S ...

Magnetic Design of Two-Phase Switched Reluctance Motor With Bidirectional Startup Capability

The symmetric structure conventionally used in two-phase switched reluctance machines (SRMs) leads to dead torque zone and issues with startup. When a phase is at the fully aligned position with respect to the rotor, the complimentary phase is completely unaligned. Within this region, excitation of either phase fails to generate sufficient startup torque. Significant research has been focused on the design of machines with large, unidirectional startup torque specific to the direction of rotation required by the given application. In this work, a conventional two-phase SRM is analyzed to reveal the underlying geometric constraints leading to startup difficulties. To overcome this, a phase shift design strategy is proposed to ensure both large starting torque and bidirectional startup capability. The design is investigated and validated through both simulation and experiments, and the results show the validity of this new configuration.

An Improved 9/12 Two-Phase E-Core Switched Reluctance Machine

There has always been a high demand for cost-efficient, reliable, low-noise, and durable low-maintenance motors, especially in high-quantity applications. A switched reluctance motor (SRM) can be a great candidate because of its rigid and simple construction. Among different SRMs, the two-phase type has the simple power converter, control unit, and geometry. In this paper, a short-flux two-phase SRM (2-phase SRM) known as E-Core 6/10 is modified to produce higher torque. The formulas for the number of rotor and stator poles have been amended, and in addition to alleviating some mechanical issues, the empty adjacent-pole spaces have been fully utilized. Comparisons are made based on simulations by 2-D finite-element analysis method and experimental results. It is obtained that for the same main dimensions, the average torque in the modified 6/10 two-phase SRM improves by about 35% that validates the new proposed motor.

Characteristics Analysis of Short Flux Path Switched Reluctance Motor

A novel kind of switched reluctance motor (SRM) with short flux path is proposed in this paper. Phase excitation in the SRM gives short flux paths, hence reducing the magnetomotive force required to drive the machine, resulting in significant reduction of copper wire and core losses compared to the typical SRM with diametric circulation of magnetic flux. To verify the performance, the characteristics analysis of a double-stator SRM, a 6/5 SRM with C-core structure, and a 4/5 two-phase SRM, which all have short flux paths, and a comparison with conventional SR motors are executed. The comparison demonstrates that the proposed motor offers some advantages in terms of torque and efficiency.

Single-Controllable-Switch-Based Switched Reluctance Motor Drive for Low Cost, Variable-Speed Applications

A new low-cost, brushless variable-speed drive requiring only a single controllable switch is presented. The proposed converter (referred to as new single-switch converter) overcomes the drawback of the original single-switch-based four-quadrant motor drive in terms of recovery energy circulation. The drive system is realized using an asymmetric two-phase switched reluctance motor (SRM), the proposed converter, and DSP controller. The new drive system retains the unique features of self-starting for all rotor position and four quadrant operation of the original single-switch-based SRM drive system. This paper presents operation principle, modeling, simulation, and design considerations of the converter in conjunction with the motor. Simulation results are based on a nonlinear model of the motor drive system. A prototype drive has been built and tested to verify its practical viability. The experimental results correlate well with the simulation, and demonstrate a performance comparable to conventional asymmetric bridge converter-based drive with two switches per phase. The market relevance of this new drive system is primarily due to its lowest cost structure, packaging compactness, self-starting feature, variable-speed operation and four-quadrant capability. Because of these features, the new drive system offers a viable alternative to conventional fixed-speed brush-commutator motors and variable-speed permanent magnet brushless dc motor drives in many high volume applications in the low-cost, energy efficient, high-volume categories such as fans, blowers, hand tools, and small appliances.

Position Estimation in Switched Reluctance Motor Drives Using the First Switching Harmonics Through Fourier Series

Position estimation using only active phase voltage and current is presented to perform high-accuracy position sensorless control of a switched reluctance motor (SRM) drive. By extracting the amplitude of the first switching harmonic terms of phase voltage and current for a pulsewidth modulation period through the Fourier series, flux linkage and position are estimated without external hardware circuitry, such as a modulator and a demodulator, resulting in increasing cost, as well as large position estimation error produced when the motional back electromotive force is ignored near zero speed. Hence, the proposed position estimation scheme covers the entire speed range, including the standstill under various loads, and it has high-resolution information depending on switching frequency. A two-phase SRM drive system, consisting of an asymmetrical converter and a conventional closed-loop proportional-integral current controller, is utilized to validate the performance of the proposed position estimation scheme in comprehensive operating conditions. The estimated values very closely track the actual values in dynamic simulations and experiments. It is shown that the proposed position estimation scheme using the Fourier series is sufficiently accurate and works satisfactorily at various operating points.

Optimum Design Approach for a Two-Phase Switched Reluctance Compressor Drive

This paper presents an optimum design approach to a two-phase switched reluctance motor (SRM) drive. The proposed drive is designed for use as a compressor drive in a small refrigerator as an alternative to the existing brushless dc motor with rare-earth magnets. In the proposed approach, three genetic algorithm loops work to optimize the lamination design and to meet the requirements for the target application while simultaneously fine-tuning the control parameters. To achieve design optimization within a realistic timescale, the repeated calculation required to obtain fitness evaluation does not use finite-element analysis but instead consists of a dynamic simulator based on an analytical expression of magnetizing curves and a geometric flux-tube-based nonlinear magnetic analysis developed specifically for this class of motor. Design results show that the proposed approach can autonomously find a feasible design solution of an SRM drive for the target application from a huge search space. The experimental studies using a two-phase 8/6 prototype manufactured in accordance with the optimized design parameters show the validity of the proposed design approach.

Novel Two-Switch-Based Switched Reluctance Motor Drive for Low-Cost High-Volume Applications

This paper presents a low-cost energy-efficient variable-speed drive for high-volume applications, such as home appliances, fans, and hand tools. A new low-cost power converter is proposed, and the drive system is realized using a two-phase switched reluctance motor and the proposed converter. The motor is capable of self-starting at any rotor position and four-quadrant operation. The converter is unique in that it has two capacitors for the energization of each phase and uses the main phase winding as energy storage for the secondary capacitor C2. The converter employs a single-switch-per-phase configuration, hence requiring only two controllable switching devices in total. The converter is inherently suited for two-phase motors having asymmetric stator phases to realize self-starting and speed reversal. Simple starting and C2 voltage control schemes are presented. This paper describes the analysis, modeling, control algorithm, and design considerations for a prototype drive system. Experimental verification and correlation with simulation results are presented. The proposed drive system offers a low-cost brushless variable-speed drive that is a potential alternative for conventional brush-commutator motors in high-volume applications.

CHARACTERISTICS OF A TWO-PHASE SRM WITH DIFFERENT ROTOR DESIGNS BASED ON FINITE ELEMENT ANALYSIS

This paper presents the operating performance of a two-phase switched reluctance motor with different rotor designs, having different air gap geometries. A two-dimension finite element analysis is used to predict the nonlinear flux linkage characteristics for the different rotor designs. The characteristics are obtained numerically at different rotor positions and different current levels for the rotor designs under consideration and then used to predict the static torque characteristics for these designs. A computer simulation procedure is devised to determine the operating performances for the different motor designs based on the predicted flux linkage and static torque characteristics. A comparison is held from the point of view of the torque developed at different speeds, motor efficiency and torque per ampere productivity of the different designs. The two???stepped air gap design proved the superiority over the other configurations.

Two-Phase SRM With Flux-Reversal-Free Stator: Concept, Analysis, Design, and Experimental Verification

The demand for high-efficiency electric motor drives at low cost is increasing, particularly, in high-volume applications, such as household appliances. Single- and two-phase machines are viable under such constraints. Between them, two-phase switched reluctance motor drives are preferred from the viewpoint of performance. This paper presents a novel two-phase switched reluctance machine (TPSRM) that is conceived for high-efficiency operation and full-load starting performance for any initial rotor position. The principle of operation of the proposed TPSRM and its unique features such as the flux-reversal-free stator for reducing core losses, the utilization of only two thirds of the stator core for each phase operation, and the resulting low noise are presented. The machine is analyzed with the 2-D finite-element analysis method. Self-starting in the proposed machine is developed with rotor pole shaping, and a unique technique to provide the desired torque characteristics is described. The effect of varying pole arcs, the number of turns per pole, asymmetric pole placement, and rotor pole shaping on torque and phase inductance is evaluated to find the best machine dimensions for a required performance as well as to understand qualitatively the influence of each variable on the machine performance. Experimental results from a 2.2-hp laboratory prototype correlate the performance predictions and validate the claims for this novel TPSRM.