On-line instantaneous torque control of a switched reluctance motor based on co-energy control

An on-line instantaneous torque control technique for a switched reluctance motor operating in the saturation region is presented. The proposed methodology is realised via the control of the instantaneous output torque of each excited phase by regulating its associated co-energy to follow a co-energy profile. As the parameters of the feedback controller are independent of the motor parameters in the analysis of the co-energy control system with the proposed methodology, the design of the proposed controller is simple when compared to that for traditional current controllers. Smooth shaft torque is obtained by torque sharing among the active phases during commutation. Simulation and experimental results confirm that the highfrequency torque ripple is reduced using the proposed algorithm.     

Modelling and predicting of a switched reluctance motor drive using radial basis function network-based adaptive fuzzy system

A novel fuzzy-neural system, which is referred to as a radial basis function network-based adaptive fuzzy system (RBFN-AFS), is presented, to model the switched reluctance machine (SRM) and predict the dynamic performances in an SRM drive system. First, we use an indirect method to measure the phase flux linkage of a 6/4 SRM and then use the co-energy method to calculate phase torque characteristics. Secondly, the RBFNAFS is designed to learn and train the SRM in the knowledge of the electromagnetic characteristics by using the hierarchically self-organising learning algorithm. This modelling scheme does not require any prior information about the SRM system apart from the input and output signals, and has good capability of generalisation and excellent convergent speed. Then, an RBFN-AFS current-dependent inverse flux linkage model and an RBFN-AFS torque model are used to simulate the various transient and steady-state performances of the 6/4 0.55 kW SRM. The simulation and experimental results based on a DSP drive platform are reported to show that the modelling scheme has good estimation performance under different operation conditions of the SRM.     

Direct instantaneous torque control of switched reluctance machines using 4-level converters

Direct instantaneous torque control (DITC) of switched reluctance machines (SRMs) using a novel 4-level converter is presented. The described DITC control strategy proposes detailed torque control regions and suitable control schemes. Using the 4-level converter, DITC can overcome voltage limitation of asymmetric converters and has a fast magnetisation and demagnetisation to improve dynamic performance and efficiency. For integrated advantages of DITC and 4-level converters, a suitable control scheme is described and analysed. Finally, the proposed DITC method of SRM drive systems using the 4-level converter is verified by simulation and comparative experiments.     

基于峰谷互补方法的开关磁阻电机转矩脉动抑制研究

开关磁阻电机的非线性电磁特性以及脉冲工作方式会产生明显的转矩脉动,针对这一问题,在分析开关磁阻电机转矩脉动产生原因和实际测量转矩脉动波形的基础上,提出了一种基于峰谷互补原理抑制开关磁阻电机转矩脉动的方法.该方法使用2套定转子参数相同的电机系统,使之产生相位互差180°电角度,幅值近似相同的转矩脉动波形,利用峰谷互补原理...     

Control of rotor torque and rotor electric power of a shaft-mounted electrical load in a mixed pole machine

A new operational mode for mixed-pole machines is presented. The proposed wound reluctance rotor machine can produce an n-phase rotor electric power from the rotor windings to a resistive or inductive load, independent of rotor torque, at any desired synchronous speed. The two-stator windings, with a different number of poles, are fed from two voltage source inverters on a common dc link. This type of machine can be used in applications that require control of both rotor torque and rotor electric power, such as contactless rotational antennas and turret systems. The machine mathematical model is presented, with open- and closed-loop control systems, simulated and experimentally validated.     

Modeling of a Switched Reluctance Machine Based on the Invertible Torque Function

This paper presents a switched reluctance machine model based on an invertible expression representing the torque-phase current relationship. The model can be useful for real-time control in high-performance applications when the command current is derived from the torque command. The two angular functions that the model requires as input can easily be calculated from the known static torque-position characteristics for two currents. However, the paper also proposes the analytical models of the angular functions. The result is a geometry-based analytical model, with all parameters derived from machine geometry and material properties. Simulation and experimental results illustrate that the model provides very high accuracy.      

平稳高效的开关磁阻电机控制算法

目的 为了提高自动化包装生产线上的产品质量,针对开关磁阻电机本身结构所引起的转矩脉动问题,提出一种基于改进电压矢量选择规律的转矩占空比控制方案.方法 首先,在原有的直接转矩控制12扇区矢量选择表的基础上设计一种新的增转矩矢量选择规律,抑制换相区的转矩脉动,并采用不产生负转矩的减转矩矢量,提高转矩电流比.此外,设计一种转矩占空比控制方法,通过对下一周期转矩的估计,来确定电压矢量作用的时间,从而使得输出转矩能够快速并且稳定地跟随给定转矩.结果 在Matlab/SIMULINK仿真环境下,搭建所提方法的模型,并与模型预测直接转矩控制、基于直接退磁矢量选择表的转矩占空比控制这2种方法搭建的模型进行对比,结果表明,文中方法的转矩脉动在各种工况下比另外2种方法减小了31％～57％,转矩电流比较模型预测直接转矩控制中方法提高了35％～44％,与另一种方法仅相差1％～2％.结论 文中方法使得开关磁阻电机在运行过程中更为平稳,且效率较高.     

Optimisation techniques for a hysteresis current controller to minimise torque ripple in switched reluctance motors

The switched reluctance (SR) motor has many benefits owing to its low cost, simple design, rugged construction and comparatively high torque-to-mass ratio. Unlike DC and induction motors, the SR motor is intended to operate in deep magnetic saturation to increase the output power density. Because of the saturation effect and the variation of magnetic reluctance with respect to rotor position, all the relevant characteristics of the machine are highly non-linear functions of both rotor position and phase current. The ultimate outcome of all these non-linearities is that the generated torque contains significant ripples. The non-linearities in the SR motor have been extensively studied and many control strategies to reduce the generated torque ripples have been proposed in the literature. Modulation of phase current profile for generating torque in the SR motor with minimum ripples was the focus of most of the research. However, the main challenge to minimise the torque ripple is to design a current controller that is able to track the modulated phase current. In this work, new techniques to optimise the widely used hysteresis current controller are studied, and experimental verifications under closed-loop speed control with the modulated reference current data are presented. The experimental results indicate that the torque ripple is reduced to lie within 5% of the desired steady torque using the proposed optimisation techniques.     

Switched Reluctance Machines as Three-Phase AC Autonomous Generator

The operation of the switched reluctance machine as an autonomous three-phase ac generator is considered. Two circuits are proposed. The generator circuit consists of only capacitors and load supplementary to the generator, but does not contain any power supply. Theoretical approaches for simulation of the three-phase autonomous switched reluctance generator are presented. The influence of the high harmonics in the phase current on the power output is discussed. Experimental and simulation results are presented     

High-performance current control for switched reluctance motors based on on-line estimated parameters

To reduce torque ripple in a switched reluctance motor (SRM) by current profiling, a high-performance current controller is necessary. This study presents a high-performance current controller for SRM drives. A Bspline neural network is used to model the non-linearity of the SRM and estimate back electromotive force (EMF) and incremental inductance on-line in real time. The on-line modelling scheme does not require a priori knowledge of the machine?s electromagnetic characteristics. Based on the on-line estimated parameters, a current controller with adjustable PI gains and back-EMF decoupling is implemented. The performance of the current controller has been demonstrated in simulation and experimentally using a four-phase 8/6 550 W SRM drive system.     

Sensored and sensorless speed control methods for brushless doubly fed reluctance motors

The study considers aspects of scalar V/f control, vector control and direct torque (and flux) control (DTC) of the brushless doubly fed reluctance machine (BDFRM) as a promising cost-effective alternative to the existing technological solutions for applications with restricted variable speed capability such as large pumps and wind turbine generators. Apart from providing a comprehensive literature review and analysis of these control methods, the development and results of experimental verification, of an angular velocity observerbased DTC scheme for sensorless speed control of the BDFRM which, unlike most of the other DTC-concept applications, can perform well down to zero supply frequency of the inverter-fed winding, have also been presented in the study     

电流自适应控制抑制开关磁阻电机转矩脉动

开关磁阻电机(SRM)的强非线性源自其双凸极结构、磁路非线性和脉冲供电方式。传统控制多采用SRM线性转矩模型求得参考电流,导致其运行时转矩脉动大。提出基于转矩偏差的双权值神经网络(DWNN)自适应PID控制与基于有限差分扩展卡尔曼滤波(FDEKF)预测电流的前馈补偿控制相结合的SRM控制策略。(1)加入偏差预处理,对转矩偏差进行非线性处理,实现"小误差,大增益,大误差,小增益"的控制,以此为基础进行双权值神经网络自适应PID的电流控制;(2)采用预测电流,构成参考电流的前馈补偿控制,提高控制系统一步预测能力。基于有限差分扩展卡尔曼滤波预测电流,将其与参考电流之差实时补偿参考电流,优化得到恒转矩下有效的控制电流,间接实现总转矩的有效控制。仿真结果证明所提控制策略能有效抑制SRM的转矩脉动。     

Improvement in the field-weakening performance of switched reluctance machine with continuous mode

A new operation mode for switched reluctance motors (SRMs), called 'continuous mode', is described. By using this mode, the torque and then power in field-weakening mode can be considerably increased without any hardware modifications. Consequently, power and torque densities of SRMs become comparable to other technologies (synchronous and induction motors) and with a field weakening operation over a large speed range. This new degree of freedom makes it possible to improve the motor design, by modifying the rotor pole arc size or the windings turns per pole. Only simulation results are presented here, for a 12/8 SRM. Results confirm that the maximum power is improved (constant power on a very large speed range) and with a higher efficiency than that in the classical discontinuous mode.     

Finite-Element Time-Step Simulation of the Switched Reluctance Machine Drive Under Single Pulse Mode Operation

This paper proposes two distinct numerical simulation methods using finite-element time-step analysis for predicting the current waveform of a switched reluctance machine drive and explains them in detail. It evaluates and compares the methods in terms of waveform results and simulation time, with the focus on only single pulse mode operation. The paper also reviews important factors that affect the simulated current waveforms. It presents and compares measured and simulated multi-phase current waveforms of a 49 kW switched reluctance machine drive under single pulse mode operation.     

Vector control application of a novel PM motor

This study introduces a new type of dual-stator permanent magnetic propulsion motor: the dissimilar frequency supplied permanent magnet synchronous motor (DFPMSM). The main advantage of the motor is its improved torque density and fault tolerance, which is well suited for electric propulsion at low speed. The vector control of the DFPMSM is presented. A torque current decoupling method is proposed to maintain the torque output while changing the torque distribution. A power loss model is derived for the power distribution strategy to achieve optimum efficiency of this motor. Simulation and experimental results are presented to verify the effectiveness of the proposed machine and control strategy.     

Multiobjective optimization method based on a genetic algorithm forswitched reluctance motor design

In this paper, a novel multiobjective optimization method based on a genetic-fuzzy algorithm (GFA) is proposed. The new GFA method is used for optimal design of a switched reluctance motor (SRM) with two objective functions: high efficiency and low torque ripple. The results of the optimal design for an 8/6, four-phase, 4 kW, 250 V, 1500 r.p.m. SRM show improvement in both efficiency and torque ripple of the motor     

Dynamic performance of a vector-controlled five-phase synchronous reluctance motor drive: an experimental investigation

Multi-phase ac motor drives are nowadays considered for various applications due to numerous advantages that they offer when compared with their three-phase counterparts. In principle, control methods for multi-phase machines are the same as for three-phase machines. The operation of an indirect vectorcontrolled five-phase synchronous reluctance machine with current control in the stationary reference frame is analysed. Performance, obtainable with ramp-comparison current control, is illustrated for a number of operating conditions on the basis of experimental results. Full decoupling of rotor flux control and torque control is realised. Excellent dynamic response is achieved during acceleration, deceleration and reversing transients of machine.     

Adaptive controller design for a synchronous reluctance motor drive system with direct torque control

The design and implementation of adaptive controllers for a sensorless synchronous reluctance drive system with direct torque control is proposed. Two adaptive control algorithms, which include adaptive backstepping control and model-reference adaptive control, are proposed to improve the performance of a sensorless direct torque control synchronous reluctance motor drive system. A digital signal processor, TMS320-C30, is used to execute the rotor position estimating technique and the adaptive control algorithms. The system shows good transient responses, good load disturbance responses and good tracking responses. Several experimental results validate the theoretical analysis. The advanced controller design for a sensorless synchronous reluctance motor drive with direct torque control is proposed.     

A New Analytical Model for Switched Reluctance Motors

We present a new analytical model for switched reluctance motors (SRMs). The model uses four coefficients, which are rotor position dependent and calculated from the flux-current-angle data using numerical curve fitting with least squares method. The four coefficients are further represented with sixth degree polynomials, which can be calculated effectively with Qin Jiushao's method. Simulated results show that the magnetic characteristics calculated with our model agree well with the original flux-current-angle data. The instantaneous electromagnetic torque derived from the developed model matches well with the numerically calculated torque. Finally, we compare dynamic simulations based on the model with experimental results and find good agreement.      

Fast Analytical Determination of Aligned and Unaligned Flux Linkage in Switched Reluctance Motors Based on a Magnetic Circuit Model

The main advantages of the switched reluctance motor are high torque, wide speed range, simple structure and fault tolerance. Because a switched reluctance motor has inherently nonlinear magnetic characteristics and a doubly salient pole structure, a finite-element analysis approach (FEA) is often adopted to obtain accurate magnetic representation. However, the solution time can be large for a FEA simulation if the mesh is detailed and/or many simulations are required. We propose a rapid analytical solution for determining the aligned and unaligned flux linkage using a magnetic circuit model. We present a simple method for obtaining the air-gap permeance for unaligned linkage. The results of our method agree well with FEA solutions.