Torque ripple minimization in switched reluctance motor drives by PWM current control
13 Feb 1994-Vol. 11, Iss: 1, pp 83-88
TL;DR: A new strategy of PWM current control for smooth operation of the drive is presented, which includes a current control strategy during commutation when torque ripple minimization is of utmost importance.
Abstract: Higher torque ripple is one of the few drawbacks of switched reluctance motor (SRM) drives, which otherwise possess excellent characteristics for applications in many commercial drives. This paper begins with an extensive review of torque ripple reduction methods that appear in the literature and then presents a new strategy of PWM current control for smooth operation of the drive. This method includes a current control strategy during commutation when torque ripple minimization is of utmost importance. >
Citations
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TL;DR: A hybrid torque-ripple-minimizing controller that incorporates the attractive features of some of the techniques developed in the past decade is presented along with simulation and experimental results.
Abstract: The torque pulsations in switched reluctance motors (SRMs) are relatively higher compared to sinusoidal machines due to the doubly salient structure of the motor. The magnetization pattern of the individual phases together with the T-i-/spl theta/ characteristics of the motor dictate the amount of torque ripple during operation. Both machine design and electronic control approaches have been used to minimize the torque ripple in SRMs. This paper presents an extensive review of the origin of torque ripple and the approaches adopted over the past decade to minimize the torque ripple. A hybrid torque-ripple-minimizing controller that incorporates the attractive features of some of the techniques developed in the past decade is presented along with simulation and experimental results.
397 citations
Cites methods from "Torque ripple minimization in switc..."
...Reference [11] presents another technique for ripple minimization using TSFs and a fixed-frequency varying-duty-cycle PWM current regulator....
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TL;DR: In this paper, a control technique for torque-ripple minimization in the switched reluctance motor (SRM) drive, based on a torque sharing function (TSF) concept, is presented.
Abstract: This paper presents a control technique for torque-ripple minimization in the switched reluctance motor (SRM) drive, based on a torque-sharing function (TSF) concept. In the proposed method, the reference torque is directly translated into the reference current waveform using the analytical expression. Optimization criteria of a TSF that are concerned with secondary objectives, such as minimization of copper losses or maximization of drive performance, are described. In addition, a novel family of TSFs is introduced. An optimal TSF can be easily extracted from the proposed family to satisfy one of the secondary objectives or to create balance between more of them. Control performances of the two extracted TSFs and the two optimized conventional (linear and sinusoidal) TSFs are compared. These four TSFs keep the copper losses to nearly the theoretical minimum. Each of them provides approximately the same operation efficiency of the considered three-phase 6/4 SRM drive. However, due to extension of the commutation angle between adjacent phases, TSFs from the proposed family provide better torque-speed characteristics. Moreover, one of them expands the possible speed range of torque-ripple-free drive operation, and another one, which provides the best torque-speed characteristics, reduces the peak phase current.
248 citations
TL;DR: This novel scheme using nonlinear TSF manipulates currents in two adjacent phases during commutation, so that efficiency and torque ripple in an SRM drive can be considerably improved.
Abstract: A novel and simple nonlinear logical torque-sharing function (TSF) for a switched reluctance motor (SRM) drive is proposed. This novel scheme using nonlinear TSF manipulates currents in two adjacent phases during commutation, so that efficiency and torque ripple in an SRM drive can be considerably improved. For constant torque generation, the switching of one-phase windings is regulated, and torque reference for the other phase stays at the previous state under the condition of a certain current limit given by the overall drive power rating. Every torque state monitored by the nonlinear logical condition determines a regulated or nonregulated torque control among two phases overlapped in commutation region, where one phase is incoming to produce the majority of torque and the outgoing current in the other phase is decreasingly controlled by the logical condition. Due to the same switching state in a nonregulated phase and the reduction of commutation period by the proposed control method, the switching number can be significantly reduced, and hence, the switching loss can be reduced. In case that one-phase regulation cannot satisfy a proper torque reference required for minimum torque ripple operation, a two-phase regulation mode is employed in the novel nonlinear TSF. In order to include magnetic nonlinearity in torque control and decrease a current tail at the end of commutation, the current of the incoming phase needs to be controlled in an increasing manner, and at the same time, the outgoing phase current tracks on an opposite direction so that torque sharing between two phases can be smoothly achieved with a minimum current crossover. The proposed control scheme is verified by some computer simulations and experimental results.
178 citations
Cites methods from "Torque ripple minimization in switc..."
...A simple torque sharing curve using a linear or cosine function has been studied to minimize torque ripple during the commutation region, so that the torque performance can be enhanced in an SRM drive [14], [15]....
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TL;DR: A technical overview for low-noise switched reluctance motor (SRM) drives in electric vehicle (EV) applications is presented, including the machine topology improvement and control strategy design for radial vibration mitigation and torque ripple reduction and the research status on this topic is summarized and forecast research hotspots are presented.
Abstract: This paper presents a technical overview for low-noise switched reluctance motor (SRM) drives in electric vehicle (EV) applications. With ever-increasing concerns over environmental and cost issues associated with permanent magnet machines, there is a technical trend to utilize SRMs in some mass production markets. The SRM is gaining much interest for EVs due to its rare-earth-free characteristic and excellent performance. In spite of many advantages compared with conventional adjustable-speed drives, SRMs suffer from torque ripple and radial distortion (and thus noise and vibration) by their nature. Therefore, for high-performance vehicle applications, it is important and urgent to optimize the SRM system to overcome the drawbacks of the noise and vibration. In order to present clear solutions to the acoustic noise in SRMs, this paper starts by analyzing the mechanism of the radial vibration and torque ripples inherent in the motors, and then focuses on the state-of-the-art technologies to mitigate the radial force and torque ripples. It highlights two categories for low-noise SRMs, including the machine topology improvement and control strategy design for radial vibration mitigation and torque ripple reduction. Advanced technologies are reviewed, classified, and compared accordingly. In addition to these methodologies, the schemes that have been developed by authors are also presented and discussed. Finally, the research status on this topic is summarized and forecast research hotspots are presented. It is our intention that this paper provides the guidance on performance improvements for low-noise SRM drives in EV applications.
176 citations
Cites methods from "Torque ripple minimization in switc..."
...Direct torque control (DTC) techniques have been employed and designed to minimize the torque ripple for SRMs [65]–[67], and the diagram is illustrated in Fig....
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05 Oct 1997
TL;DR: An adaptive fuzzy control scheme for torque ripple minimization of switched reluctance machines (SRM) is presented and shows good response in both cases.
Abstract: An adaptive fuzzy control scheme for torque ripple minimization of switched reluctance machines (SRM) is presented. The fuzzy parameters are initially chosen randomly and then adjusted to optimize the control. The controller produces smooth torque upto the motor base speed. The torque is generated over the maximum positive torque producing region of a phase. This increases the torque density and avoids high current peaks. The controller is robust towards errors in the rotor position information which means inexpensive crude position sensors can be used. Detailed simulation and experimental results are presented. The controller shows good response in both cases.
169 citations
References
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01 Jul 1980
TL;DR: In this article, the theory and potential of a family of doubly salient electronically-switched reluctance motors is explored. But the most recent prototype has achieved a continuous rating which is 1.4 times that of the equivalent induction motor.
Abstract: The paper explores the theory and potential of a family of doubly salient electronically-switched reluctance motors. It is demonstrated that the machine provides the basis for fully-controllable variable-speed systems, which are shown to be superior to conventional systems in many respects. The motor retains all the advantages normally associated with induction motors and brings significant economy in the drive electronics. The basic modes of operation, analysis, design considerations and experimental results from a range of prototype motors up to 15 kW at 750 rev/min are described. The most recent prototype has achieved a continuous rating which is 1.4 times that of the equivalent induction motor.
791 citations
TL;DR: In this paper, an experimental study of the acoustic noise emitted from an inverter-driven doubly salient variable-reluctance motor (VRM) is presented, and a list of possible noise sources is given.
Abstract: An experimental study of the acoustic noise emitted from an inverter-driven doubly salient variable-reluctance motor (VRM) is presented. A list of possible noise sources is given. Through a series of experiments, all but one source is eliminated as being important, and the remaining source is shown to be dominant. The dominant noise source is the ovalizing deformation of the stator due to its radial magnetic attraction to the rotor. The emitted noise is particularly strong when the frequency of deformation coincides with that of a natural mechanical resonance of the stator. Several methods of reducing acoustic noise emission are studied. One successful method is the introduction of dither into the control of the motor in order to spread the spectrum of noise excitation and reduce its coupling to the mechanical resonance of the stator. >
406 citations
29 Jun 1992
TL;DR: In this paper, the position-phase current profile for current feeding a four-phase, 4 kW switched reluctance motor is optimized to minimize both the average and peak current and hence improves the dynamic performance of the novel six-switch, current-fed, 4-kW, 40 kHz IGBT inverter.
Abstract: Optimal precalculation of the position-phase current profile for current feeding a four-phase, 4 kW switched reluctance motor results in a single-input, linear, decoupled output torque controller that provides low torque ripple. A bicubic spline interpolation was used to model the nonlinear experimental data. The algorithm is based on minimizing both the average and peak current and hence improves the dynamic performance of the novel six-switch, current-fed, 4 kW, 40 kHz IGBT inverter. Test results are presented. >
160 citations
"Torque ripple minimization in switc..." refers methods in this paper
...The method of ripple reduction by optimizing current overlap during commutation at all torque levels were studied in [ 6 ]....
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...Various methods of torque control appear in the literature [3,4,5, 6 ,7]....
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...Some of the previous studies have outlined methods of obtaining the torque-angle-current characteristics accurately by conducting static tests on the motor [5, 6 ,7]....
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29 Jun 1992
TL;DR: In this paper, a method for minimizing the instantaneous torque ripple in switched reluctance (SR) machines is investigated and implemented based on estimating the instantaneous SR motor torque from the flux linkage versus current and rotor position characteristic curves via a bi-cubic spline interpolation.
Abstract: A method for minimizing the instantaneous torque ripple in switched reluctance (SR) machines is investigated and implemented. The method is based on estimating the instantaneous SR motor torque from the flux linkage versus current and rotor position characteristic curves via a bi-cubic spline interpolation. These coefficients are computed offline, stored in a given memory location of the control processor, and used by two routines that are capable of estimating the rotor position and electromagnetic torque from the phase voltages and currents. The estimated output torque is then compared to a constant reference value, and the result of this comparison drives a current regulator that generates the proper motor phase currents. The ripple minimization scheme is simple and does not require a very fast processor. Its feasibility is confirmed via simulation and some preliminary experimental results. >
85 citations
"Torque ripple minimization in switc..." refers methods in this paper
...Various methods of torque control appear in the literature [3,4,5,6, 7 ]....
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...The method described by Moreira in [ 7 ] is based on the estimation of the instantaneous SR motor torque from the flux linkage versus current and rotor position characteristics curves....
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...Some of the previous studies have outlined methods of obtaining the torque-angle-current characteristics accurately by conducting static tests on the motor [5,6, 7 ]....
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TL;DR: In this paper, a nonlinear dynamic model is developed and decomposed into separate slow and fast subsystems, and a feedback control is designed so that, whenever the fast subsystem is at equilibrium, the dynamics of the slow subsystem are input-output equivalent to a second-order transfer function.
Abstract: It is shown how to supply two-time-scale nonlinear control design techniques to switched reluctance motors. A nonlinear dynamic model is developed and decomposed into separate slow and fast subsystems. A feedback control is designed so that, whenever the fast subsystem is at equilibrium, the dynamics of the slow subsystem are input-output equivalent to a second-order transfer function. The use of reduced-order feedback linearization methods leads to improved performance by reducing torque ripple. Experimental results from a laboratory implementation of a position control system are presented. On the basis of measured overshoot, risetime, and settling time, the prototype response is consistent with the desired linear response to within 23% error on average. The transient behavior of the motor can thus be adjusted over a wide range, and in a reasonably predictable fashion, by simply varying the gains of the outermost loop. >
72 citations