Hala Hannoun

Design of an SRM Speed Control Strategy for a Wide Range of Operating Speeds

This paper presents a speed control strategy for a switched reluctance machine (SRM). Two control strategies are compared to select the most appropriate control that allows the SRM to operate in wide-speed-range operation. The proposed strategy is first designed to control the speed in discontinuous conduction mode and is then extended to operate in continuous conduction mode as well. In this paper, the transition from three different operating modes is detailed, and the experimental results validate the proposed strategy.

Experimental Validation of a Switched Reluctance Machine Operating in Continuous-Conduction Mode

This paper presents an innovative torque control strategy for a switched reluctance machine (SRM) operating in continuous-conduction mode (CCM). The proposed strategy was first designed to control the torque in discontinuous-conduction mode and then extended to operate in CCM as well. With CCM, the torque can be increased at high speed without modifying the number of turns, the source voltage, or the converter; it is achieved through the control. Reviews of past control strategies, as well as the principle of this mode and its influence on the machine performance, are presented. The advantages and drawbacks of the proposed strategy are outlined. In particular, the power and torque densities of the SRM are improved so that this machine becomes comparable with ac machines without the drawback of field weakening. A new control law has been studied and implemented; simulation and experimental results are provided to demonstrate the effectiveness of the proposed control.

Analytical modeling of switched reluctance machines including saturation

Nowadays, the switched reluctance machine has become a serious candidate in industry applications : hybrid electric vehicles, aircraft starter/generator systems and washing machines. Because of the rapid progress in processors (DSP), control algorithms are becoming more and more promising. Nevertheless an accurate model is essential, first to predict its performance and obtain high quality control, and second to use sensorless controllers enabling cost reduction and reliability increase. This paper presents an analytical model of the inductance and of the torque, based on the results of a 2D finite element analysis (FEA) applied to an 8/6 prototype machine. The model takes into account the nonlinear characteristics due to the magnetic saturation. The position dependency is represented by a limited number of Fourier series terms and the nonlinear variation with current is expressed by means of polynomial functions. The analytical calculations are introduced, then the results of the proposed model are compared to those issue from the 2D FEA approach.

Gain-scheduling PI current controller for a Switched Reluctance Motor

Switched reluctance motor drives are under consideration in various applications requiring high performance applications such as in servomotor drives, electric vehicle propulsion and jet engine starter-generators. Current or torque control constitutes the heart of control in such drive systems to obtain the desired high bandwidth in torque and speed responses. The nonlinear characteristics due to magnetic saturation complicate the issue. This paper presents a design methodology for a digital proportional-integral current regulator : a gain adaptation is used with respect to both position and current to insure better performance and stability. In addition, a back ElectroMotive Force (EMF) compensation is included in order to eliminate its effect on current regulation. A comparative study of the classical PI current controller with the proposed gain scheduling PI current controller incorporating the induced EMF compensation is made.

Evaluation of a switched reluctance motor with magnetic slot wedges

The switched reluctance motor is a good candidate for electrical traction and more specifically in automotive applications. The conventional switched reluctance motor presents two major drawbacks which are torque ripple and stator vibrations. In this work, a solution to limit these problems is proposed: a switched reluctance motor with magnetic slot wedges is used to reduce the impact of vibrations through the analysis of the radial forces applied on the stator teeth, and their harmonic content. Indeed, these forces cause an undesirable vibro-acoustic behavior. In addition, it is shown that the proposed design allows the reduction of torque ripple which are the cause of power-train vibrations.

Design of an optimized SRM control architecture based on a hardware/software partitioning

This paper presents an effective digital speed control implementation for a switched reluctance machine. An optimized architecture is proposed based on a hardware/software partitioning in order to implement it on a System on Programmable Chip. This solution leads to a user-friendly development solution without over pending for performance or sacrificing features. Finally, the proposed strategy achieves lower current and torque ripples in a large speed range compared to a software implementation.

Design of an enhanced adaptive hybrid controller for switched reluctance motors

This paper deals with current control in switched reluctance motors with an objective of maximizing torque generation. First, the structure of a hybrid controller is recalled. This controller, which is a combination of an on-off and a PI controller, is efficient for controlling SRMs using square wave current pulses. Next, advantages and drawbacks of this controller with high current dynamics are detailed. Finally, an enhanced structure of this controller overcoming these drawbacks is presented. The advantages of the new controller are detailed and validated by simulation.

Position and speed estimations of a switched reluctance machine using current harmonic

In the motor control industry, DSP systems offer major improvements over analog designs, enabling notably to replace speed or position sensors by the implementation of sensorless control algorithms. In this paper, we propose a new viable method which estimates the rotor position and velocity of a switched reluctance machine from the rotor saliencies present in the current signal. This approach is based on both two adjustable digital filters and a frequency estimator, which is fitted to this particular application