Prototype Switched Reluctance Motor Research Articles

A method for reducing torque ripple of switched reluctance motor based on partitioned TSF

In this paper, a new torque sharing function control strategy is proposed to reduce the torque ripple. The traditional torque ripple methods, such as exponential and linear torque allocation strategies, the torque generation capacity of each phase and the power limitation of the power converter is not taken into account, in this paper, the communication region is divided into three intervals by establishing a new partitioning standard. According to the re-established reference function of torque generation, the torque deviation caused by phase current tracking error is compensated according to the torque generation capacity. Both optimization of torque ripple suppression and copper loss minimization are taken into consideration in this paper. To verify the validity and performances of the proposed TSF methods, simulations and experiments have been implemented in a 12/8 structure Switched Reluctance Motor prototype. This method can be applied to other switched reluctance motors with different topologies. Result shows lower current tracking error and better performance of torque ripple minimization compared with the conventional two-interval compensation method.

Quasi-Z-Source-Fed SRM Drive for Torque Ripple Minimization and Speed Range Extension With Three-Switch Conduction

This paper proposes a quasi-Z-source (QZS)-based modular switched reluctance motor (SRM) drive to suppress the source current ripple, minimize the torque ripple, widen the constant torque range and speed range, and enhance the system reliability. To take full advantages of QZS unit and modular power modules, the QZS-based modular SRM converter is firstly constructed. Subsequently, a three-switch conduction-based current compensation mechanism is developed to deal with the torque plummet issue caused by the inherent series excitation mode. Meanwhile, a novel four-region DITC strategy is proposed to further suppress torque ripple. Furthermore, a voltage regulation method is developed based on compensation mechanism to suppress the source current ripple and provide great assistance to implement the above strategy more effectively. In addition, the shoot-through state can be evenly distributed among the four bridge arms, which is conducive to balance the heating dissipation of power devices for improved service life of power converter. To validate the feasibility and effectiveness, the experiments are carried out on a 150W three-phase 12/8 SRM prototype.

Torque ripple reduction of switched reluctance motor using direct instantaneous torque control and adaptive turn‐on technique for electric vehicle applications

AbstractDirect Instantaneous Torque Control (DITC) with an adaptive turn‐on angle technique is presented in this paper to improve the torque ripple of the Switched Reluctance Motor (SRM) for Electric Vehicle applications. Torque ripple suppression is achieved by employing two operating modes during the commutation interval. First, both the outgoing and incoming phase states are modified to track the required torque during the incoming phase's minimum inductance area. As soon as the incoming phase leaves its minimum inductance zone, the outgoing phase is demagnetised, and only the incoming phase state is modified for torque tracking. In addition, a closed‐loop regulator is used to dynamically control the turn‐on angle that drives the incoming current to reach its first peak at the instant of switching between the two operation modes when the rotor and stator poles initiate overlap, thus increasing the motor's efficiency. Simulation results showed that the proposed control method has superior advantages over the traditional DITC and Average Torque Controller. Furthermore, the simulation results were verified experimentally using a four‐phase 4kW, 8/6 SRM prototype.

Investigation of Torque Performance and Flux Reversal Reduction of a Three-Phase 12/8 Switched Reluctance Motor Based on Winding Arrangement

The goal of this paper is to present a comparative analysis of two types of winding arrangements for a three-phase 12/8 switched reluctance motor (SRM), where short- and fully-pitched winding arrangements under unipolar operation are considered. From the analytical results, the short-pitched winding has the best torque per copper weight ratio. The core loss based on counting the number of flux reversals in the stator yoke for each winding arrangement is also proposed and mentioned. To reduce the magnetic flux reversals in the stator core, changing the direction of the magnetic flux path by modifying the winding polarities of the short-pitched winding could reduce 10–13% of core loss compared to the conventional winding. A 1 kW, 12/8 SRM prototype for the ventilation fan application is constructed and tested in order to verify the design consideration of winding configuration. At the rated condition, a maximum efficiency around 82.5% could be achieved.

Calculation and Analysis of Eddy-Current Loss in Switched Reluctance Motor

The eddy-current loss of switched reluctance motor (SRM) is studied and analyzed in this paper. As a significant part of core loss, eddy-current loss has a great influence on motor performance. First, the average magnetic flux waveforms in every distributed region are derived from the magnetic equivalent circuit (MEC) model. Based on this, each harmonic of magnetic density is obtained by adopting the fast Fourier transform (FFT) method for further calculation. Then, each harmonic eddy-current loss is computed by sinusoidal magnetic density and the total eddy-current loss in different region of motor is derived by superposing of them. Therefore, the calculated results at different speed and conduction angles of each region are analyzed. Finally, the 3D finite element (FE) model is established in software FLUX and the experimental platform of the SRM prototype is built.

Winding inductance and performance prediction of a switched reluctance motor with an exterior-rotor considering the magnetic saturation

This paper deals with an analytical method to effectively calculate the inductance of an exterior-rotor switched reluctance motor (SRM), which evaluates the winding inductance of both the active section and the end section, accounting for the influence of core saturation. According to the inductance calculated by the analytical model, the flux linkage table and torque table can be established, and the steady state performance such as phase current, flux linkage, copper loss and core loss can be predicted. Effectiveness of this method is verified by the finite element method as well as by experimental results of a 12/8 SRM prototype.

A High-Performance Indirect Torque Control Strategy for Switched Reluctance Motor Drives

This paper proposes a high-performance indirect control scheme for torque ripple minimization in the switched reluctance motor (SRM) drive system. Firstly, based on the nonlinear torque-angle characteristic of SRM, a novel torque sharing function is developed to obtain the optimal current profiles such that the torque ripple is minimized with reduced copper losses. Secondly, in order to track current accurately and indirectly achieve high-performance torque control, a robust current controller is derived through the Lyapunov stability theory. The proposed robust current controller not only considers the motor parameter modeling errors but also realizes the fixed frequency current control by introducing the pulse width modulation method. Further, a disturbance-observer-based speed controller is derived to regulate the motor speed accurately, and the load torque is considered an unknown disturbance. The simulations and experiments on a 1.5 kW SRM prototype are carried out to demonstrate the effectiveness of the proposed high-performance indirect torque control strategy. Results verify the superiority of the proposed strategy with respect to the torque ripple suppression, system efficiency, and antidisturbance.

Synthetic Hybrid-Integral-Threshold Logic-Based Position Fault Diagnosis Scheme for SRM Drives

Reliable rotor position measurement is quite necessary for ensuring accurate commutation control in many kinds of motor drives, such as switched reluctance motor (SRM) and brushless dc motor (BLDC). Traditionally, the Hall sensors and photoelectric switch sensors are widely used in most of these low-cost motor drive systems. In these systems, the rotor position needs to be decoded from the discrete voltage pulses measured by the sensors. Thus, to develop an online position pulse signal fault diagnosis scheme with fast fault-monitoring capability is quite vital for avoiding the abnormal driving control and improving the overall system reliability. In this article, a position pulse signal fault diagnosis scheme based on synthetic hybrid-integral-threshold logic is proposed for SRM drives. In this method, the complementary position pulse signals of each sensor are used as the independent reference signals. By applying special integral calculations on each reference signals and capturing their rising and falling edges, the position pulse fault cases like high-level and low-level faults can be diagnosed immediately with the synthetic thresholds’ comparison logic, respectively. To verify the validity of the proposed method, a 1-kW 12/8 structure SRM prototype with three independent Hall sensors installed is used as a test machine. The experimental results show that this method can diagnose the position fault of each position sensor independently and ensure very fast position fault detection even under dynamic operations with speed transients. Furthermore, the method can be implemented without additional hardware and complex computation, which is quite suitable for constructing a reliable position measurement module to assist the rotor position sensors.

DC-Biased Sinusoidal Current Excited Switched Reluctance Motor Drives Based on Flux Modulation Principle

This article proposes a novel current control technique for three-phase switched reluctance motor (SRM) drives with harmonic current suppression, based on developed flux modulation principle. For conventional SRM control systems, the unsmooth and discontinuous stator current cause serious torque ripple, vibration, and noise, due to the doubly salient motor structure. In order to overcome shortcomings in conventional drives, the developed flux modulation principle is employed for the SRM in this article, where the working principle is investigated in detail, including the excitation magnetic field, flux modulator, and armature magnetic field. Then, a new control strategy is presented to generate the dc-biased sinusoidal current, by employing the modular open-winding converter. Furthermore, a harmonic current suppression strategy is put forward for the new drive to improve the motor performance, by employing a developed vector proportional integral control scheme. Compared to existing SRM drives, the torque ripple and motor vibration can be both significantly reduced, the motor structure and winding arrangement do not need to be changed, and the robustness of the motor system is improved. Finally, experiments are carried out on a three-phase 12/8 SRM prototype to verify the effectiveness of the proposed SRM drive and control strategy.

Torque Ripple Reduction of SRM Drive Using Improved Direct Torque Control With Sliding Mode Controller and Observer

The industrial application of the switched reluctance motor (SRM) is limited by its high torque ripples caused by the doubly salient structure. In this article, an improved direct torque control (DTC) with sliding mode controller and observer is developed to reduce the torque ripples of a four-phase SRM. First, a sliding mode controller based on a new reaching law is developed for designing a sliding mode speed controller (SMSC) for the DTC system. An antidisturbance sliding mode observer (ADSMO) is then proposed and combined with the SMSC to build a composite antidisturbance speed control strategy. Moreover, detailed simulation validations are carried out to reveal the effectiveness of the new reaching law, SMSC and ADSMO. Finally, experiments are conducted to verify the performance of the proposed SMSC–ADSMO in a DTC system with a four-phase SRM prototype.

A New Constructed Geometry of A Switched Reluctance Motor for Reduced Torque Ripple (Dept.E)

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Experimental Sensorless Control of Switched Reluctance Motor for Electrical Powertrain System

In this paper a mechanical sensorless control of Switched Reluctance Motors (SRMs) scheme of an electric vehicle (EV) powertrain is presented. The aim is to develop a soft sensors implementation for position and speed measurements of SRM. This contribution is focused on an extended Kalman filter and a sliding mode observer. The proposed observers are designed to generate speed and position estimations with the purpose of achieving highly robust speed control. The performances of these two observers are assessed and their robustness are analyzed. The design also includes a robustness analysis of the proposed mechanical sensorless control scheme under conditions which take the parameter variations and the load torque into account. To carry out this work, experiments are highlighted on an experimental test bench of 8/6 Switched Reluctance Motor prototype.

An On-Board Charger Integrated Power Converter for EV Switched Reluctance Motor Drives

This article presents a power converter topology with integrated driving and charging capability of switched reluctance motor (SRM) drive for electric vehicle (EV) application. In the driving mode, the bus voltage can be adjusted flexibly by the front-end buck converter, which meets the requirements of the speed open-loop and closed-loop control. Besides, higher voltage demagnetization can be achieved by connecting the upper freewheeling diodes of the asymmetric half-bridge converter to the battery bank, thus can accelerate the demagnetization process, extend the dwell angle, and enhance the output of the motor. In battery charging mode, a bridgeless rectifier converter is constructed by utilizing two-phase windings of the SRM and the existing power devices of integrated power converter, without additional inductors and charging units. The battery charging and power factor correction control can be realized by closed-loop control of charging current. Detailed analysis and experiments on a 1 kW 12/8 structure prototype SRM validate the effectiveness of the proposed technologies.

An Unsaturated Inductance Reconstruction Based Universal Sensorless Starting Control Scheme for SRM Drives

In this article, an universal sensorless starting scheme considering magnetic saturation effects is proposed to control the switched reluctance motor (SRM) drives. In this approach, the full-cycle unsaturated inductance can be reconstructed by converting the saturated incremental inductance into the unsaturated inductance with a simple mathematical model in the conduction region. Based on the reconstructed three-phase full-cycle unsaturated inductance, the inductance vector coordinate transformation method and the linear region inductance model based method can be applied for estimating the rotor position even under high load starting case. To verify the validity of the proposed methods, experiments have been implemented in a 1-kW three-phase 12/8 structure SRM prototype. The experimental results verify that the unsaturated inductance reconstruction scheme can transfer the nonlinear magnetic saturation problem into an unsaturation problem, and thus the rotor position estimation at the sensorless starting state can be simplified. The method can realize the initial position estimation and reliable sensorless starting control even under load conditions with only very simple initial inductance data acquisition, position partition logics design, and mathematic modeling. In addition, as the back-electromotive force is eliminated indirectly in the inductance calculation process, the adaptable speed range can also be extended.

Improved Analytical Nonlinear Model for Switched Reluctance Motor Using Gaussian Distribution Probability Density Function

In this manuscript, a new nonlinear analytical model of switched reluctance motor based on Gaussian distribution probability density function is proposed. In this model, inductance profile of the switched reluctance motor is considered as a Gaussian function which is a nonlinear function in terms of phase current and rotor position. Extracted inductance data from a switched reluctance motor prototype are used to determine the proposed nonlinear analytical model. Simulations are firstly performed to verify the effectiveness of the proposed Gaussian model in a simple control scheme. In addition, measured data acquired from an experimental implementation of the control scheme for the switched reluctance motor prototype are also used to validate the proposed model. During the validation, experimental results on the motor prototype with DSP-based digital controller (TMS320F28335) are achieved under various rotor positions and currents in low and rated speed. The outcome is then compared with a previously developed polynomial inductance model. Comparing the achieved results, through the proposed nonlinear analytical model and those of the polynomial inductance model, it is seen that the model provides a high degree of accuracy while it is involved with fewer coefficients.

Design and Experimental Verification of a 72/48 Switched Reluctance Motor for Low-Speed Direct-Drive Mining Applications

Typically, a geared drive system is used to connect an induction motor of 1500 rpm with a Raymond Pulverizer of 105 rpm in mining applications. This system suffers from low efficiency and a heavy motor drive. This paper proposes a novel design of a 75 kW, 72/48 switched reluctance motor (SRM) for a low-speed direct-drive as for mining applications. The paper is focused on the design and comparative evaluation of the proposed machine in order to replace a geared drive system whilst providing a high torque low-speed and direct-drive solution. The machine performance is studied and the switching angle configuration of the machine is also optimised. The efficiency of the whole drive system is found to be as high as 90.19%, whereas the geared induction motor drive provides only an efficiency of 59.32% under similar operating conditions. An SRM prototype was built and experimentally tested. Simulation and experimental results show that the drive system has better performance to substitute the induction motor option in mining applications.

Modeling of a Switched Reluctance Motor Under Stator Winding Fault Condition

A new method for modeling stator winding fault with one shorted coil in a switched reluctance motor (SRM) is presented in this paper. The method is based on artificial neural network (ANN), incorporated with a simple analytical model in electromagnetic analysis to estimate the flux-linkage characteristics of SRM under the stator winding fault. The magnetic equivalent circuit method with ANN is applied to calculate the nonlinear flux-linkage characteristics under stator winding fault condition. A stator winding fault 12/8 SRM prototype system is developed to verify the effectiveness of the proposed method. The results for a stator winding fault with one shorted coil are obtained from the proposed method and from the experimental work on a developed prototype. It is shown that the simulation results are close to the test results.

Split Converter-Fed SRM Drive for Flexible Charging in EV/HEV Applications

Electric vehicles (EVs) and hybrid EVs are the way forward for green transportation and for establishing low-carbon economy. This paper presents a split converter-fed four-phase switched reluctance motor (SRM) drive to realize flexible integrated charging functions (dc and ac sources). The machine is featured with a central-tapped winding node, eight stator slots, and six rotor poles (8/6). In the driving mode, the developed topology has the same characteristics as the traditional asymmetric bridge topology but better fault tolerance. The proposed system supports battery energy balance and on-board dc and ac charging. When connecting with an ac power grid, the proposed topology has a merit of the multilevel converter; the charging current control can be achieved by the improved hysteresis control. The energy flow between the two batteries is balanced by the hysteresis control based on their state-of-charge conditions. Simulation results in MATLAB/Simulink and experiments on a 150-W prototype SRM validate the effectiveness of the proposed technologies, which may provide a solution to EV charging issues associated with significant infrastructure requirements.

Position Signal Faults Diagnosis and Control for Switched Reluctance Motor

An accurate rotor position signal is quite necessary for high-performance control of switched reluctance motor (SRM). In general, the position signal faults may lead to abnormal operation, which deteriorates the reliability of the switched reluctance drive system. Thus, it is quite vital but still a challenge to develop a control strategy that can diagnose and control the position signal faults in an autonomous way. In this paper, a square-wave position signal edge prediction-based control strategy is proposed for position signal faults diagnosis and position faults recovery. Integrated with the rotor position fault-tolerant control method, the SRM drive system can maintain reliable operation under different position signal fault conditions. In addition, a phase inductance slope-based sensorless control method is proposed for position fault-tolerant control under the extreme case with failure of all position signals. To verify the validation of the proposed methods, the experiments have been implemented in a 12/8 structure SRM prototype. The results show that the proposed control methods can further improve the fault-tolerant capability of the SRM system.

Design Procedure for a Longitudinal Flux Flat Linear Switched Reluctance Motor

This article presents a new comprehensive design procedure for longitudinal flux flat linear switched reluctance motors. The design process comprises all the steps from detailing the specifications to sizing the prototype to validating the design, and it can be applied to three types of flux flat linear switched reluctance motors: single sided, double sided, and modified double sided. The design is based on an analytical formulation of the average translation force determined using a simplified non-linear energy conversion loop. Special emphasis is devoted to the calculation of the number of turns per phase. A two-dimensional finite-element analysis, corrected to take into account end effects, and a lumped parameter thermal analysis were used to refine and/or validate the design. Finally, a linear switched reluctance motor prototype was built following the proposed design and was verified by experimental measurements.