Pole Switched Reluctance Machine Research Articles

The Study of SRM Sensorless Control Strategy Based on SOGI-FLL and ADRC-PLL Hybrid Algorithm

The inductance model used in traditional sensorless control methods for switched reluctance machines (SRMs) exhibits high-order harmonics. The precision of the motor may be impacted by the buildup of rotor estimate errors caused by these harmonics. To address this issue, this paper proposes a novel method for SRMs that employs a hybrid algorithm combining an enhanced second-order generalized integrator (SOGI)-based frequency-locked loop (FLL) and an active disturbance rejection control (ADRC)-based phase-locked loop (PLL). This approach involves coordinate transformation and parameter identification to reconstruct the motor inductance model. Rotor position errors are calculated using the unsaturated inductance difference method. In order to enhance the accuracy of motor position estimation, a hybrid algorithm is employed to efficiently filter out harmonic errors and mitigate the tremor effect caused by the rotor position differential algorithm. This hybrid algorithm enables the estimate of the motor’s speed and rotor position. A sensorless control simulation model was developed using a 12/8 pole SRM to assess the motor’s performance under varying load conditions. Based on the results obtained, it is established that the application of this method can accurately estimate the rotor’s position and rotational speed and thus improve the performance of position sensorless control. Ultimately, a prototype system for a switched reluctance motor was created, and the effectiveness and feasibility of the proposed control technique were confirmed through experimental validation. This presents an innovative approach to engineering practice.

Acoustic Noise Mitigation of Switched Reluctance Machines With Leaf Springs

In this article, a leaf spring insertion to the stator back iron is proposed to reduce vibration and acoustic noise in a switched reluctance machine (SRM). The back iron of the tooth tip is curved out and the material made up of carbon spring steel is placed to dampen the vibration due to radial force. A 6/4 stator/rotor pole SRM is designed and its natural vibration mode frequencies are determined through finite-element analyses. The optimal current waveform is applied to the SRM model using the multidisciplinary coupled simulation method to determine the radial force with the harmonic orders. In the final step, the proposed leaf spring architecture is optimized to achieve the most dampening for the effective radial force harmonic orders. The simulation and experimental results confirmed the effectiveness of the leaf spring insertion in reducing the noise and vibration in SRMs.

Acoustic Noise Mitigation in High Pole Count Switched Reluctance Machines Utilizing Skewing Method on Stator and Rotor Poles

Multiphysics analysis and experimental validation of acoustic noise reduction in a high pole count, high power, switched reluctance machine (SRM), through skewing are explored in detail in this work. An iterative optimization strategy covering electromagnetic, structural, and thermal domains is proposed to investigate the effect of different skewing methods and angles on a 24-stator slot/16-rotor pole (24/16) SRM rated at 100 kW. The contributions of this work are twofold. First, electromagnetic impact, considering average torque, torque ripple, radial and tangential air gap forces, of symmetric and asymmetric skewing on stator and rotor is studied in this work. Second, the impact of skewing methods on acoustic noise and vibration performance is studied and presented in detail. The study reveals that skewing both the stator and rotor by the same amount has superior electromagnetic performance over other types of skewing. Multiphysics simulations conducted, predict a 10.5 dBA reduction in the acoustic noise, compared to a baseline design with no skew, for an optimized rotor-stator skewing angle of 13.75°. Finally, 100 kW prototypes of the baseline and the optimized skewed SRM were constructed and subjected to wide speed range testing. Simulation and test results closely follow each other and validate the effectiveness of the proposed skew design in mitigating acoustic noise and vibration in high pole count SRMs.

An Optimization-Based Initial Position Estimation Method for Switched Reluctance Machines

A new method to detect the initial rotor position of switched reluctance machine (SRM) is presented in this article. Unlike most conventional position estimation methods, the proposed method does not need any extra premeasurement and only the data with finite element method (FEM) are required. First, a linear regression model (LRM) is presented to describe the relationship between FEM and measured inductance characteristics. Then, to detect the position, the residual sum of squares of the proposed LRM is considered as an objective function, which is a convex function with rotor position. The rotor position can be estimated by minimizing the objective function with the golden-section search method. Finally, the accuracy of the proposed estimation algorithm is validated by the experimental results on a three-phase 12/8 pole SRM prototype. Compared with the existing position estimation methods, the proposed method has higher accuracy and less measurement effort. The proposed method can serve as a supplement to provide accurate initial position information for incremental position sensors.

Four-Quadrant Sensorless Operation of Switched Reluctance Machine over the Wide Speed Range

This paper presents four-quadrant sensorless control in switched reluctance machine (SRM) over the wide speed range. The proposed sensorless control technique could be employed not only at low speed with current chopping control (CCC) but also at high speed with angle position control (APC). At startup and low speed, the narrow voltage pulse is injected into the idle phases and the rotor position zone is determined by comparing the measured flux linkage with four flux linkage-current curves. The same flux linkage-current curves also can be adopted for rotor positions estimation at medium and high speeds. Two flux linkage-current characteristic curves in the inductance rising zone are employed to estimate the rotor position for motoring mode and the other two curves in the inductance falling zone are used to estimate the rotor position for braking mode. The experiments on a three-phase 12/8 pole SRM drive platform are carried out to verify the effectiveness of the proposed sensorless control technique.

Minimal Current Sensing Strategy for Switched Reluctance Machine Control With Enhanced Fault-Detection Capability

This paper focuses on a minimal current sensing strategy and fault detection of switched reluctance machines (SRMs). In order to reduce the number of required current sensors in multiphase motor drives, the optimal selection and location of current sensors is presented in consideration of the precise actual phase current measurement, open- and short-circuit fault detection. The proposed scheme requires two current sensors to replace the phase current sensors placed in each phase without any additional devices for multiphase SRMs to achieve a more compact and low-cost drive. Different current regulation methods are employed for single phase conducting region and commutation region. To obtain the phase currents from the proposed approach, different settings of the pulsewidth modulation signals for adjacent phases during the commutation region are implemented. The simulation and experiments on a four-phase 8/6 pole SRM are carried out to verify the effectiveness of this approach in the healthy and faulty cases.

Acoustic Noise Reduction of a High-Efficiency Switched Reluctance Motor for Hybrid Electric Vehicles With Novel Current Waveform

One of the major topics of switched reluctance machines (SRMs) is how to reduce the acoustic noise and vibration without decreasing the efficiency. In this paper, a few novel current profiling methods are proposed to reduce the acoustic noise by flatting the radial force sum and to reduce optimal torque ripple with best efforts to enhance the efficiency. The proposed method is adopted to the 18/12 pole SRM, which has identical outer dimensions and competitive torque, output power, efficiency, and operating region of the permanent-magnet motor used in the hybrid vehicles. It is found that the proposed method can improve not only the radial force ripple characteristic but also the iron loss minimization. The efficiency enhancement is also found to be possible in a few cases depending on the demanding criteria; thanks to the phase shift of the fundamental component of the current waveform. The proposed method is verified in the experiments.

Predictive Control Based Constant Current Injection Scheme for Characterization of Switched Reluctance Machine

A novel constant current injection-based characterization scheme for the switched reluctance machine (SRM) is proposed here. Unlike conventional characterization methods where the rotor is locked at a fixed position, the current injection-based method maintains the phase current constant while the machine runs at constant speed. A novel current controller, required for the proposed constant current injection scheme, is also proposed in this paper. The predictive control-based current controller works without the machine model being available. The proposed current controller is validated experimentally and is then used to characterize a 4 kW, 1500 r/min 8/6 pole SRM. The characteristics obtained are found to be in good agreement with those obtained using conventional locked rotor tests.

Four‐quadrant sensorless control in switched reluctance machine drive using pulse injection based on special flux linkage curves

This study presents four-quadrant sensorless control in switched reluctance machine (SRM) drive for startup and low speed. The proposed control method is based on two special flux linkage-current characteristic curves which can be obtained expediently and quickly without the need of external mechanical fixtures. The narrow voltage pulse is injected into the idle phases by the power converter and the rotor position zone within an electrical cycle is determined by comparing the measured flux linkage with the two flux linkage-current curves. The judgment rules and flow-chart of rotor positions estimation are proposed to implement the four-quadrant operation in SRM drive. The effectiveness of the proposed sensorless technique is investigated through a series of experiments on a three-phase 12/8 pole SRM drive platform. The experimental results show that the four-quadrant sensorless control of SRM is implemented without the requirements of additional hardware circuit and complicated computation.

Influence of Stator and Rotor Pole Arcs on Electromagnetic Torque of Variable Flux Reluctance Machines

The influence of stator and rotor pole arcs on electromagnetic torque of variable flux reluctance machines (VFRMs) having different stator and rotor pole combinations is investigated. Different from 6/4 stator/rotor pole switched reluctance machines, which usually employ equal stator pole arc and stator slot opening, unequal stator pole arc and slot opening can boost the torque density of the VFRM. Moreover, the optimal rotor pole arc to rotor pole pitch ratio in VFRMs is \(\sim ~1/3\) and the optimal stator pole arc is equal to or slightly smaller than the optimum rotor pole arc. For a 6-pole stator, the 4-, 5-, 7-, and 8-pole rotor VFRMs with the optimal stator and rotor pole arcs can increase the average torque by 1%, 4%, 30.7%, and 72.9% compared with those having equal stator pole arc and stator slot opening. In addition, the 6/7 stator/rotor pole VFRM exhibits the largest torque density. Prototype machines with optimal stator and rotor pole arcs are manufactured and measured to validate the analysis.

Artificial intelligence-based rotor position estimation for a 6/4 pole switched reluctance machine from phase inductance

This paper presents artificial intelligence-based rotor position estimation techniques for a three phase, 6/4 pole switched reluctance machine one based on fuzzy logic and another on adaptive neuro-fuzzy inference system (ANFIS). These techniques are applied for modelling the nonlinear rotor position of SRM using the magnetisation characteristics of the machine. Fuzzy logic technique is greatly suited to model general nonlinear mapping between input and output spaces. ANFIS has a strong nonlinear approximation ability which could be used for nonlinear modelling of the machine and its real time implementations. In this paper, the best features of fuzzy logic and ANFIS are utilised to develop the computationally efficient rotor position model θ(I, L) for SRM. Mathematical model for θ(I, L) using fuzzy inference system (FIS) and ANFIS has been successfully arrived, tested and presented for various values of phase currents (Iph) and phase inductance (L) of a nonlinear SRM. It is observed that both FIS and ANFIS are highly suitable for rotor position θ(I, L) modelling of SRM which is tested to be in good agreement with the training and checking of data used for modelling.

Estimation of phase inductance profile in a three-phase 6/4 pole switched reluctance machine

This paper presents a non-linear inductance profile estimation of a Switched Reluctance Machine (SRM) using real-time applicable modelling techniques. The estimation techniques are based on regression analysis and Adaptive Neuro-Fuzzy Inference System (ANFIS). Mathematical models of phase inductance L(I,θ) using both the techniques have been successfully tested for various values of phase currents (Iph) and rotor positions (θ) of a non-linear SRM. It is observed that the proposed techniques are highly suitable for inductance L(I,θ) modelling of SRM, which is found to be in good agreement with the training data used for modelling.

Control Performance Analysis of SR S/G System Based on FEM

Switched reluctance machine (SRM) has many outstanding advantages, and can be widely used in many electromechanical applications. However, it’s relatively difficult to analyze the control performance of SRM due to strong nonlinearity of the electromagnetic field. In this paper, the performance of SRM is analyzed by finite element method (FEM). Firstly, the simulation model of a 4-phase 8/6 pole SRM is built, and then the steady-state and dynamic simulation are carried out. In steady-state simulation, the magnetization and torque characteristics are obtained by parametric method. In dynamic simulation, the performance, include current and torque curve, under both motoring and generating mode are given. The simulation and analysis results are useful for performance optimization of SRM.

Design of 2000kW switched reluctance machine system

The switched reluctance machine system with high reliability and fault tolerance capability has good perspective for large power applications. The machine, the topology of the power converter main circuit and the control strategy should be taken into account as a whole for the design of the switched reluctance machine system. Four-phase 8/6 pole switched reluctance machine and four-phase asymmetric bridge power converter should be adopted in large power system with consideration of the fault tolerance capability and low voltage & current rating of power switches in power converter. The primary election of the structure parameters for 2000kW switched reluctance machine can be calculated based on the output equation and the equation of the turn numbers of phase winding. The nonlinear simulation of the system was made by taking as a whole the magnetization curves of the machine obtained by using two dimensional finite element electromagnetic field calculation, the topology of the power converter main circuit and the control strategy. The electromagnetic parameters and the structural parameters of the machine, the control parameters of the system were modified continuously until the output power and efficiency were satisfied. The magnetic flux paths of the prototype were given. The hardware-in-the-loop simulation on the controller and the system was finished based on RT-LAB simulator.