功率滑模控制在开关磁阻速度控制的应用

ed and minimize the torque ripple, but their work did not include magnetic saturation. It is important to emphasize that SR motor is usually operated in deep magnetic saturation to increase output power density. Yang et al [6] developed sliding mode speed controller for SR motor for direct drive servo application. Karakas and Vardarbasi [7] investigated dynamic model, flux current rotor position and torque current rotor position values of SR motor and used these values on speed control by self tuning fuzzy PI controller with artificial neural network. Hussain and Hossain [8] have presented the modelling, simulation and control aspects of four quadrant SR motor. A complex model is described for the physical motor simulation to incorporate the important dynamics of SR motor. In this paper a sliding mode control with maximum two phase excitation scheme is proposed for speed control applications. The proposed design uses less power as compare to conventional schemes where all phases are to be energised. Comparison of power losses is carried out with [8]. This paper Keywords— SR motor, sliding mode control, mathematical is organized as follows. In Section II, control oriented mathemodelling, speed regulation, tracking control matical model of the SR motor is derived. Controller design for both regulation and tracking controls is proposed in secI. INTRODUCTION tion III. Section IV describes commutation scheme for the Switched reluctance motor (SRM) has received considerable proposed controllers. Simulation results are discussed in secattention as an alternate candidate for general purpose industion V and section VI concludes the work presented in this trial drive applications. This is due to following major reasons. paper. References are given at the end. 1) Simple mechanical construction. 2) Low cost driver electronics. II. MATHEMATICAL MODEL OF THE SYSTEM 3) Rigid structure, and In any nonlinear controller design, the important step is to 4) It can be controlled by high speed digital processor. develop the reliable mathematical model of the system for The stator and the rotor of SR motor has salient poles proper control system design and performance evaluation. The with no windings or magnets on the rotor that makes SR mo- system under consideration is 3-Phase 6/8 SR motor whose tor very suitable for operations at high speed [1]. The torque is parameters are given in Table1. The control oriented mathedeveloped in SR motor due to tendency of rotor poles to align matical model of SR motor consists of electrical and mechaniwith the excited phase. The sequential excitation of the phases cal dynamic subsystems [2], which are described as under. based on rotor position rotates the motor. Torque is nonlinear A. Electrical subsystem function of phase current and rotor position. Due to particular nature of torque production, it is independent of the polarity of To understand the electrical subsystem, consider the folphase current and polarity of torque depends upon the rotor lowing relation which describes the voltage applied to one position. The behaviour of SR motor and its drive is so phase of an SR Motor. nonlinear that modern control techniques are required to conௗఒೕ ൫ఏǡ௜ೕ ൯ trol motor and command it to achieve fast dynamic response. ‫ݑ‬௝ ൌ ܴ௝ ݅௝ ൅ ݆ ൌ ͳǡʹǡ͵ (1) ௗ௧ Due to enhancements in nonlinear control theory, several nonlinear control techniques such as sliding mode, artificial Where ‫ݑ‬௝ ǡ ܴ௝ ǡ ݅௝ represent the input, resistance, and curneural network, fuzzy logic, feedback linearization etc. have rent in the jth phase. ߣ௝ ൫ߠǡ ݅௝ ൯ is the flux linkage in the jth phase been developed in the last two decades for the control of SR and it represents the nonlinear function of rotor position and motor and like systems. John and Eastham [4], and Forrai et al phase current. Neglecting mutual inductances among the [5] have used sliding mode control for SR motor to control phases, the flux linkage can be written as the following:
Power Efficient Sliding Mode Control of SR Motor for Speed Control Applications
M. Rafiq1, S. U. Rehman1, Q. R. Butt1, A.I. Bhatti2
1. Centre for Advanced Studies in Engineering (CASE), Islamabad, Pakistan. 2. Muhammad Ali Jinnah University, Islamabad, Pakistan.
Abstract. In this paper a novel method for speed regulation and tracking of Switched Reluctance Motor is proposed. The proposed method uses the concept of only energizing all those phases of the motor which can contribute to desired polarity of torque at one time for power saving. The suggested scheme is based on Sliding Mode Technique. A mathematical model of SR motor is derived for controller design purpose. The power efficiency is derived by not energizing all the phases at a given time; this is because not all the phases of SR motor can produce torque with the same polarity because of the particular motor construction. Thus our controller chooses the appropriate phases, at any control instant, to get the desired torque output with minimum phase currents. The speed regulation scheme is compared with the conventional sliding mode control taken from the public literature. Simulation results confirm the effectiveness of the proposed regulation controller. The proposed scheme reduces the power loss of SR motor. A tracking control based on the new scheme is also presented.