Torque ripple minimization in switched reluctance motor drives by PWM current control
TL;DR: A new strategy of PWM current control for smooth operation of the drive is presented that 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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12 Oct 1998
TL;DR: In this paper, the authors investigate the capabilities of the switched reluctance motor (SRM) for electric vehicle and hybrid electric vehicle applications, which is carried out in two steps: the first step involves the machine design and the finite-element analysis to obtain the static characteristic of the motor; the second step is used in the development of a nonlinear model to investigate the dynamic performance of the designed motor.
Abstract: Land vehicles need their drivetrain to operate entirely in constant power in order to meet their operational constraints, such as initial acceleration and gradability, with minimum power rating. The internal combustion engine (ICE) is inappropriate for producing this torque-speed profile. Therefore, multiple gear transmission is necessary with the ICE in a vehicle. Some electric machines, if designed and controlled appropriately, are capable of producing an extended constant power range. The purpose of this paper is to investigate the capabilities of the switched reluctance motor (SRM) for electric vehicle and hybrid electric vehicle applications. This investigation is carried out in two steps. The first step involves the machine design and the finite-element analysis to obtain the static characteristic of the motor. In the second step, the finite-element field solutions are used in the development of a nonlinear model to investigate the dynamic performance of the designed motor.
503 citations
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
TL;DR: In this article, two improved torque sharing functions for implementing torque ripple minimization (TRM) control are presented, which are dependent on the turn-on angle, overlap angle, and the expected torque.
Abstract: Two improved torque-sharing functions for implementing torque ripple minimization (TRM) control are presented in this paper. The proposed torque-sharing functions are dependent on the turn-on angle, overlap angle, and the expected torque. This study shows that for a given torque the turn-on angle and the overlap angle have significant effects upon speed range, maximum speed, copper loss, and efficiency. Hence, genetic algorithm is used to optimize the turn-on angle and the overlap angle at various expected torque demands operating under the proposed TRM control in order to maximize the speed range and minimize the copper loss. Furthermore, four torque-sharing functions are used to derive the optimized results. At the same time, a fast and accurate online approach to compute the optimal turn-on and overlap angles is proposed. Therefore, this paper provides a valuable method to improve the performances of switched reluctance motor drives operating under TRM control.
320 citations
Cites background from "Torque ripple minimization in switc..."
...In this paper, the sinusoidal TSF in [3] is improved....
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...First, the authors will develop improved exponential and sinusoidal TSFs based on [1] and [3], and describe linear and cubic TSFs in Section II....
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...Husain and Ehsani [3] present a sinusoidal TSF....
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...The sinusoidal TSF developed in [3] is only the function of the turn-on and turn-off angles....
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...Husain and Ehsani develop a sinusoidal TSF to implement TRM in SRM drives [3]....
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10 Dec 2002
TL;DR: The control algorithm offers a wide drive operating range without the use of a high-resolution shaft position sensor or sensitive position estimation techniques, and works without torque profile functions and auxiliary phase commutating strategies.
Abstract: 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.
266 citations
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
References
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TL;DR: In this article, a state feedback control algorithm was proposed to compensate for all the nonlinearities and decouples the effect of stator phase currents in the torque production for a single-link manipulator with SRM.
Abstract: Motivated by technological advances in power electronics and signal processing, and by the interest in using direct drives for robot manipulators, we investigate the control problem of high-performance drives for switched reluctance motors (SRM's). SRM's are quite simple, low cost, and reliable motors as compared to the widely used dc motors. However, the SRM presents a coupled nonlinear multivariable control structure which calls for complex nonlinear control design in order to achieve high dynamic performances. We first develop a detailed nonlinear model which matches experimental data and establish an electronic commutation strategy. Then, on the basis of recent nonlinear control techniques, we design a state feedback control algorithm which compensates for all the nonlinearities and decouples the effect of stator phase currents in the torque production. The position dependent logic of the electronic commutator assigns control authority to one phase, which controls the motion, while the remaining phase currents are forced to decay to zero. Simulations for a direct drive, single link manipulator with the SRM are reported, which show the control performance of the algorithm we propose in nominal conditions and test its robustness versus the most critical parameter uncertainties of payload mass and stator resistance.
461 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 was studied in [ 6 ]....
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TL;DR: In this paper, the concept of instantaneous torque control was introduced as an objective worth pursuing in the application of such digital IC's to drive systems, which would in principle permit the fastest possible response and the elimination of torque ripple, along with many other advantages not possible with conventional control algorithms.
Abstract: In the control of adjustable speed drives, the performance of inexpensive digital integrated circuits is approaching the stage where traditional control algorithms may be displaced by new algorithms that better exploit their speed and the functional capabilities of their software. The concept of ``instantaneous torque control'' is introduced as an objective worth pursuing in the application of such digital IC's to drive systems. Instantaneous torque control would in principle permit the fastest possible response and the elimination of torque ripple, along with many other advantages not possible with conventional control algorithms, most of which are set up to control a time-averaged torque. Some of the fundamental principles of instantaneous torque control are developed for the switched reluctance motor, which is used as an example because, like the brushless dc permanent-magnet motor with concentrated windings, it has the potential for rapid response, but it can have appreciable torque ripple with unfavorable firing angles. A reference frame transformation that would eliminate the rotor position from the voltage and torque equations is not known for either of these machines. This opens up a number of interesting questions as to the generality of instantaneous torque control algorithms, and whether they can be incorporated into the general or unified theory of electrical machines.
143 citations
"Torque ripple minimization in switc..." refers methods in this paper
...A similar method of torque control based on a defining function was proposed in [ 8 ]....
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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
...Some of the previous studies have outlined methods of obtaining the torque-angle-current characteristics accurately by conducting static tests on the motor [5]-[ 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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...Current profiling at commutation has not been discussed in detail in the published literature, although the control algorithms described in [ 7 ]-[ 111 apply for single-phase conduction as well as for multiple-phase conduction....
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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