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.

Feedback linearizing control of switched reluctance motors

A new type of doubly salient machine is presented in which the field excitation is provided by a nonrotating permanent magnet (PM). This doubly salient PM (DSPM) motor is shown to be kindred to square waveform PM brushless DC motors. Linear and nonlinear analysis has been performed to investigate the characteristics of this new type of PM motors. A prototype DSPM motor has been designed, and a comparison has been made between this new type of motor and the induction motor. It is shown that, by fully exploiting modern high-energy PM material and the doubly salient structure, the DSPM motor can offer superior performance over existing motors in terms of efficiency, torque density, torque-to-current ratio, and torque-to-inertia ratio, while retaining a simple structure amenable to automatic manufacture. >

A novel permanent magnet motor with doubly salient structure

Although design of the variable reluctance (switched reluctance( type of synchronous machine has experienced intense activity in recent years, relatively little effort has been expended on improving the torque capability of the synchronous reluctance type of motor drive. Based on the analysis presented in this paper, it appears that substantial improvements can be made in the design of such motor drives resulting in performance characteristics which match or, indeed, perhaps even exceed that of the induction machine.

Synchronous reluctance machines―a viable alternative for AC drives?

Switched reluctance machines have emerged as an important technology in industrial automation; they represent a real alternative to conventional variable speed drives in many applications. This paper reviews the technology status and trends in switched reluctance machines. It covers the various aspects of modeling, design, simulation, analysis, and control. Finally, it discusses the impact of switched reluctance machines technology on intelligent motion control.

Switched Reluctance Motor Modeling, Design, Simulation, and Analysis: A Comprehensive Review

A number of power electronic converter circuits exist for switched reluctance motor (SRM) drives which are generally applicable to most loads. A larger number of circuits exist which are suitable for particular niche applications, but which have the potential to be the most cost-effective within that niche. Due to the variable methods of operation of these circuits and the rapid progress in this field, comparisons of these circuits have so far been limited. This paper attempts to bring together the sum total of power converter topologies so far published for SRM drives. A novel classification methodology is presented. The power converters are compared using a straightforward total semiconductor VA per phase sum, and the relative cost of the drive system elements is considered.

Power electronic converters for switched reluctance drives

Switched reluctance (SR) drives offer the advantages of simple and robust motor construction, high speeds, high overall efficiencies over a wide operating range of torque and speed, simple power converter circuits with a reduced number of switches, and excellent controllability. The basis of these claims is explained. The history of the SR system, in particular the extensive research at Nottingham and Leeds Universities, and the basic operating principles and design considerations for motors and power converters are reviewed. Alternative configurations are discussed. The difficulties of establishing a simple mathematical model for the motor and of calculating torque and inverter VA requirements are examined. A comparison of the VA requirements for SR and pulsewidth modulation (PWM) is given for a 7.85-kW system. Measured drive performance is discussed in terms of efficiency over an operating envelope, specific output, controllability, and power converter ratings. Earlier traction drives, incorporating a constant power range and including regeneration, are reported together with the constant torque industrial drives and more recent traction extensions. The long-term potential of the drive is discussed for a wide range of applications. A comprehensive list of references is provided.

Roy J. Blake

Papers

High-Performance Switched Reluctance Brushless Drives