DITC-direct instantaneous torque control of switched reluctance drives

This paper presents an online instantaneous torque control technique for switched reluctance machines called direct instantaneous torque control. The method comprises two novel aspects. First, torque is estimated as a function of terminal quantities, i.e., flux linkage and phase current. Hence, torque estimation is independent of the rotor position. Secondly, high-bandwidth drive performance is obtained by implementing a digital torque hysteresis controller. Thus, the method works without torque profile functions and auxiliary phase commutating strategies. Therefore, the control algorithm offers a wide drive operating range without the use of a high-resolution shaft position sensor or sensitive position estimation techniques. Experimental and simulation results are presented in this paper.     

直接转矩控制在开关磁阻电机中的应用与研究

阐述了开关磁阻电机(SRM)直接转矩控(制DTC)策略的原理,指出直接转矩控制的核心在于电压矢量的选择及开关表的建立,给出了DTC在SRM中应用的具体实现方法。对基于直接转矩控制策略的SRM电机转矩控制进行了仿真及实验研究,仿真结果表明,这种策略能够较好地抑制转矩脉动,系统动静态特性良好,实现方法简单。     

开关磁阻电机直接瞬时转矩控制的优化研究

为改善开关磁阻电机(SRM)的转矩脉动和效率,提出了一种改进的SRM直接瞬时转矩控制(DITC)方法。该方法采用了灵活的转矩分配方式获得各相参考转矩,用来对瞬时转矩进行闭环控制;同时增加了角度优化方案,根据每相绕组导通期间的累积转矩误差、转速和参考转矩等变量,通过模糊算法实现电机开通角度的在线调整,动态的改善转矩误差和电机的效率。在MATLAB/Simulink软件中分别根据改进前后的DITC方法建立SRM控制系统仿真模型,仿真试验结果表明所提的优化方法能够达到较小的转矩误差和相电流,实现了电机的平稳、高效控制。     

High-dynamic four-quadrant switched reluctance drive based on DITC

This paper presents the development of a four-quadrant switched reluctance machine (SRM) drive for high dynamic applications. Comprehensive fundamentals and analysis for operating switched reluctance machines in four quadrants are presented. The drive is designed based on a high dynamic control strategy called Direct Instantaneous Torque Control (DITC). The functionality of DITC is discussed in detail for both motoring and generating operation. A methodology to generate switching functions directly by the hysteresis torque controllers for SRMs is proposed. The proposed controller was prototyped and tested on a digital signal processor/field-programmable gate array development platform. High dynamic operation in both motoring and generating mode and the transition between these modes are validated by experimental results presented at the end of this paper.     

Studies of torque ripple in a switched reluctance motor under a controlled average torque value in a low-velocity mode

In the case of adjusting the average torque value of switched reluctance motors, torque ripple is most pronounced in a low-velocity mode. In this mode, the motor phase-currents are usually forcibly limited; therefore, owing to the available voltage margin, by properly selecting the positions of phase switching, one can influence the shape of the phase-currents within certain limits and, thereby, achieve a decrease in the torque ripple. This paper considers the possibilities of reducing torque ripple using very common methods for restricting the phase-current, such as voltage control and current control. Using simulation modeling in the Matlab–Simulink environment, the best combinations of control actions are found, with which torque ripple is minimal. It is shown that, by using the first method of phase-current restriction, the reduction in torque ripple under certain conditions is achieved via a forced pulling of the range of phase-current increase due to a later switching on of the phase with a simultaneous increase in the voltage across this phase. In a number of cases, the desired effect can be achieved only owing to a certain delay in the command for switching the phase off with respect to the position corresponding to a single-switching mode. For the second method of phasecurrent restriction, the best switching conditions are found for fixed levels of current restriction determined from the desired values of the average motor torque, and independent adjusting of the switch-on and switchoff positions of its phases.     

五电平拓扑下开关磁阻电机直接瞬时转矩控制

针对开关磁阻电机转矩脉动,提出开关磁阻电动机五电平驱动拓扑结构和滞环控制策略.研究和分析五电平拓扑的五电平导通原理,并与不对称半桥驱动电路三电平导通进行比较.结合开关磁阻电机绕组导通和直接瞬时转矩控制原理,设计五电平驱动下开关磁阻电机直接瞬时转矩滞环控制策略,并且进行仿真实验.仿真结果证实与不对称半桥电路相比,五电平拓...     

Unified theory of torque production in switched reluctance andsynchronous reluctance motors

A method is described for calculating the average and instantaneous torque of the synchronous reluctance motor from a knowledge of the trajectory of the phase flux-linkage versus phase current [i-ψ] waveform, i.e., the same method as used with the switched reluctance motor. This allows a direct comparison between torque production in the two motors to be made. Analytical and finite-element analysis both show that the [i-ψ] loci of the synchronous reluctance motor are ellipsoidal in shape and are not limited to the first and third quadrants as in the switched reluctance motor. The [i-ψ] loci of the synchronous reluctance motor are not bounded by the magnetization curves in the same sense as in the switched reluctance motor and rely upon mutual coupling between phases for correct operation     

Smart bacterial foraging algorithm based controller for speed control of switched reluctance motor drives

In this paper, a innovative methodology for Switched Reluctance Motor (SRM) drive control using Smart Bacterial Foraging Algorithm (SBFA) is presented. This method mimics the chemotactic behavior of the E. Coli bacteria for optimization. The proposed algorithm uses individual and social intelligences, so that it can search responses among local optimums of the problem adaptively. This method is used to tune the coefficients of a conventional Proportion–Integration (PI) speed controller for SRM drives with consideration of torque ripple reduction. This matter is done by applying the proposed algorithm to a multi-objective function including both speed error and torque ripple. This drive is implemented using a DSP-based (TMS320F2812) for an 8/6, 4-kW SRM. The simulation and experimental results confirm the improved performance of adjusted PI controller using SBFA in comparison with adjusted PI controller using standard BFA. Excellent dynamic performance, reduced torque ripple and current oscillation can be achieved when the coefficients of PI controller are optimized by using SBFA.     

SPICE-assisted simulation of controlled electric drives: anapplication to switched reluctance drives

An example of simulation of a closed loop controlled electric device that shows the feasibility of simulating the equipment by means of a general-purpose electronic circuit analysis program is described. The SPICE program was used because of its well-known facilities for simulating electronic circuits. A method for extending the SPICE facilities to simulate the electromechanical energy conversion and the drive control is reported. The simulation of a switched reluctance motor drive with closed loop speed control is considered, and the results were validated by experimental tests executed on an industrial drive     

Low-cost battery-powered switched reluctance drives with integral battery-charging capability

This paper presents a low-cost battery-powered drive using switched reluctance motors. The converter topology proposed in this paper is cost effective while still maintaining an energy-efficient system for battery-powered drives. The proposed drive not only achieves cost-effective and efficient battery motoring, but also battery charging with minimal additional power semiconductor components. Charging is achieved through the windings of the switched reluctance motor, thus eliminating the need of external bulky transformers and separate charging units.     

An algorithm for direct torque control of field oriented asynchronous motor drives

Contents The dynamic behaviour of fully digital control systems is strictly related to the duration of the sampling interval. The minimum length of this period depends exclusively on the time needed for the execution of all the required operations. Therefore, the minimization of computing time is one of the most important goals to be achieved in order to improve the accuracy of electrical drives with fully digitalized control systems. The best results can be obtained using fast programming languages and short sets of computing instructions. This goal is achieved using a proper feeding algorithm for asynchronous motor drives called direct, because it links directly the requested torque and magnetic flux to the input voltages.

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Ein Algorithmus zur direkten drehmomentregelung bei feldorientierten antrieben mit asynchronmotor

Übersicht Die Dynamik einer vollständig digitalen Regelung ist eng verbunden mit der Dauer des Abtast-Intervalles. Die Mindestdeuer der Periode hängt ausschließlich von der erforderlichen Rechenzeit ab. Deswegen ist die Minimierung der Rechenzeit eines der wichtigsten Ziele für die Genauigkeit elektrischer Antriebe mit vollständig digitaler Regelung. Die besten Ergebnisse können mit schnellen Programmiersprachen und kurzen Befehlssätzen erlangt werden. Das Ziel wird erreicht durch einen geeigneten Algorithmus für Asynchronmotoren. Dieser Algorithmus wird direkt genannt, weil er das elektromagnetische Moment und den magnetischen Fluss direkt mit den Eingangsspannungen verbindet.

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List of symbols i_r instantaneous value of the rotor currents symmetrical component referred to the stator - i _s instantaneous value of the stator currents symmetrical component - l _r rotor leakage inductance referred to the stator phase - l _s stator phase leakage inductance - m number of stator phases - p pole-pairs number - r _r rotor phase resistance referred to stator phase - r _s stator phase resistance - v instantaneous value of the stator voltages symmetrical component - J, J _m total and motor inertia - L _m air-gap motor inductance - P rated power - T _el motor electromagnetic torque - T _L load torque - V _R rated voltage - instantaneous rotor position - _R rated angular speed     

开关磁阻电机的滑模变结构控制

针对开关磁阻电机存在磁场严重的非线性且数学模型不精确等问题,提出了一种滑模变结构控制方法。它主要是通过切换函数从而不间断地来回切换系统量,系统总约束在切换面上,然后系统的状态变量自动地滑到原点。利用滑模变结构控制的快速性和完全自适应性,设计了滑模变结构控制的开关磁阻电机调速系统,同时推导出了该方法的数学模型,最后编程实现并在实验台上调试。实验结果证明,与常规的控制策略相比,滑模变结构控制改善了系统的动态性能,有较强的鲁棒性,且在无需知道电机精确模型的情况下可有效克服转矩脉动。     

开关磁阻电机无位置传感控制器研究

针对机械式位置传感器增加控制系统复杂性和降低系统可靠性的问题,提出了开关磁阻电机一种新的无位置传感控制器。在建立开关磁阻电机电感模型基础上,推导无位置传感器数学模型,构建无位置传感器控制系统。通过测量激励相电压和电流,估算转子实际位置,采用电流斩波控制方法控制开关磁阻电机低速运行,采用角度位置控制方法控制开关磁阻电机高速运行。对该无位置传感系统进行仿真,并实现了对开关磁阻电机无位置传感器的控制。实验结果表明该方法能在较宽调速范围内准确地估计开关磁阻电机转子位置。     

开关磁阻电机再生制动控制方法

针对开关磁阻电机再生制动控制中存在制动电流波动大的问题,提出一种基于电流预测的开关磁阻电机再生制动控制方法.分析了电机制动过程中其对应功率开关的工作模式及相应状态向量的确定方法,研究了基于电流预测的开关磁阻电机再生制动控制的具体设计方法,并对其效果进行了仿真验证,同时与传统变制动相电压占空比控制法进行了对比仿真分析,结...     

High-grade control of switched reluctance machines

This paper formulates the objectives associated with high-grade torque control of switched reluctance motors (SRMs). Low torque ripple is a natural outcome of high bandwidth torque control. Smooth torque operation is only uniquely defined together with a secondary objective, such as maximum efficiency, maximum torque-speed capability, maximum power factor, etc., as the SRM does not enjoy the inherent distribution between phases that characterizes AC drives. By introduction of the flux-angle parameter, operation at any point between maximum torque-current ratio and maximum torque-flux ratio is possible. A systematic approach to waveform design is developed and is evaluated using both simulation and experimental testing of a SRM servo-drive system. This approach, which can be regarded as a functional equivalent of AC vector control, starts from machine parameters and gives smooth torque operation with maximized torque-speed range and/or efficiency. Excellent dynamic performance is obtained for speed and position control, together with optimized low torque ripple operation     

High-precision torque control of reluctance motors

The high-precision torque control of a reluctance motor for servo applications is described. The prototype is a three-phase, eight-pole reluctance motor driven by a MOSFET inverter. The current control and the speed control are performed by software of the digital signal processor TMS 32010. The motor is supplied by sinusoidal current, and two current control methods are proposed. One is based on a vector control principle to achieve the linearity between current and torque, and another is developed to obtain the maximum torque/current ratio. Due to the saliency, the instantaneous torque contains a large ripple component. In the case of the test motor, the torque ripple was as much as 26% of the rated torque under sinusoidal current drive. The experiment showed that the ripple component could be reduced to 6% by superimposing a compensation current component on the current reference     

基于分段解析建模的开关磁阻电机在线转矩估算方法*

针对目前开关磁阻电机采用单一解析模型进行在线转矩估算存在模型复杂、精度低的问题,提出一种基于分段解析建模的开关磁阻电机在线转矩估算方法。根据开关磁阻电机在一个电周期内磁链特性曲线的对称性及其定转子极弧的结构特点,提出将其半个电周期划分为5个区间,分别建立了每个区间的磁链与转矩简化解析模型,并通过有限元分析及构建基于DSP28335的实验系统分别对上述模型的估算精度与运算时间进行了验证,同时与传统单一解析模型进行了对比分析,结果表明,所提出的分段解析模型相较于传统单一解析模型,不仅有效提高了转矩估算精度,而且显著减少了运算时间,因而有助于提高开关磁阻电机调速系统的控制精度与动态性能,具有较好的应用价值。     

一种开关磁阻电机非线性磁链与转矩建模方法

开关磁阻电机(SRM)由于磁化曲线高度饱和非线性的特点,造成传统的电机性能分析和建模方法很难运用到SRM中。根据SRM磁链曲线的特点,提出了一种带修正因子的反正切函数来建立SRM模型的方法。在获得SRM 5个特殊转子位置处的9个磁链数据点的基础上,利用傅立叶级数分解和反正切函数来拟合SRM的磁链特性,并推导出电感和电磁转矩模型。该模型函数表达式简单、系数修改方便、计算精度高,并且能够直观的反映SRM的磁链、电感和转矩变化情况。以一台550 W、6/4极SRM为例,进行了仿真与实验比较,结果表明该模型能够很好的反映SRM的实际工作状况,验证了所建模型的精确性和有效性。     

开关磁阻电动机互感特性及其对转矩的影响

开关磁阻电动机在两相励磁的工作条件下,定转子轭部磁场高度饱和使每相磁链有所减小.通过引入互感的方法可以定量计算磁链的减小量,并给出了互感计算式,利用有限元法分析了一台样机互感随转子位置和电流的变化规律,理论推导了互感对平均转矩影响的程度,研究了四相8/6极开关磁阻电动机稳态转矩波形在两种绕组连接方式下的不规则特性,结合互感特性,提出了改变不对称相绕组参数的技术方案.研究结果表明:电磁参数优化后,开关磁阻电动机的最小转矩和平均转矩均得以提高,转矩脉动减小,转矩波形规则.     

Phase current modulation of switched reluctance motor to minimize torque ripple

This paper presents a simple technique to minimize torque ripple of a switched reluctance motor (SRM). The technique is based on the control of the sum of the square of the phase currents by using only two current sensors and analog multipliers. The control characteristics of the SRM drives are analyzed for operation of the motor in the linear region of its magnetic characteristics. The simulation and experimental results of the proposed method are given. The advantages and limitations of the proposed circuit are explained.