In this paper, a nonlinear varying-network magnetic circuit (VNMC) modeling method is developed for doubly salient permanent-magnet (DSPM) motors. The method is used to analyze the static characteristics of DSPM motors by specific performance calculations, in which the interaction between the permanent-magnet field and the armature current field, as well as magnetic saturation, are taken into account. Two newly proposed DSPM motors (12/8-pole and 6/4-pole) are used as examples. There is good agreement between the results of the nonlinear VMMC modeling method and finite-element analysis. Moreover, the nonlinear VNMC method offers the advantage of calculating, effectively and efficiently, the static characteristics of DSPM motors having different dimensions, parameters, and conditions. Finally, the proposed method is verified by experimental testing of a 6/4-pole prototype.

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Nonlinear varying-network magnetic circuit analysis for doubly salient permanent-magnet motors

A standard design procedure for a single-sided and longitudinal flux-based linear switched reluctance machine is developed in this paper. The proposed design procedure utilizes the rotating switched reluctance machine design by converting the specifications of the linear machine into the equivalent rotary machine. The machine design is carried out in the rotary domain, which is then transformed back into the linear domain. Such a procedure brings to bear the knowledge base and familiarity of the rotary machine designers to design a linear machine effectively. This paper contains the illustration of the proposed design procedure for a 4.8-m-long prototype. An analysis procedure is developed with a magnetic model and results from it are verified with finite-element analysis prior to construction of the prototype. Extensive experimental correlation in the form of inductance versus position versus current and propulsion force versus position versus current to validate the analysis and design procedure is given in the paper.

Design of a linear switched reluctance machine

Linear switched reluctance motor (LSRM) drives are investigated and proved in this study as an alternative actuator for vertical linear transportation applications such as a linear elevator. A one-tenth-scaled prototype elevator that is focused on a home elevator with LSRMs is designed, and extensive experimental correlation is presented for the first time in this paper. The proposed LSRM has twin stators and a set of translator poles without yoke placed between the two stators. The features of the LSRM and the prototype elevator are described. Furthermore, a control strategy for the prototype elevator is introduced consisting of four control loops, viz., (1) current, (2) force, (3) velocity, and (4) position feedback control loops. Force control of the experimental prototype elevator employs the proposed force distribution function. A trapezoidal velocity profile is introduced to control vertical travel position smoothly during ascent, descent, and stop of the elevator. Conventional proportional-integral controller is used for the current and velocity control loops and their designs are described. The proposed control strategy is dynamically simulated and experimentally correlated. The analytical and experimental results of this paper prove that LSRMs are one of the strong candidates for linear elevator propulsion drives.

Ropeless Elevator With Linear Switched Reluctance Motor Drive Actuation Systems

Design and Control of A Ropeless Elevator with Linear Switched Reluctance Motor Drive Actuation Systems

Linear switched reluctance motors (LSRMs) for the primary propulsion of a ship elevator is proposed and investigated for the first time in this paper. To achieve the stated objective, a new type of LSRM is proposed with twin stators and a translator between them with no back iron in the translator. The proposed configuration of the LSRM is designed, simulated, analyzed, compared with traditional LSRMs, and verified by experimental measurements. The number of LSRM propulsion subsystems required is studied with a view to minimize their weights and an optimization study for that purpose is developed. Unique placement of the LSRM propulsion systems on the elevator is presented. The propulsion force is generated using one phase or multiphase excitation. To reduce propulsion force pulsations, a major requirement in elevators, controlled multiphase excitation using one of the known force distribution functions (FDF) is an acceptable solution. In this paper, it is proved that the currently available FDFs are able to reduce the force pulsations but are not able to meet the peak force command for the system. Consequently, the velocity and position control do not meet even the elementary performance requirements any more. A new FDF is proposed in this paper and presented to overcome the problem caused by a conventional FDF. The control system with the proposed FDF is derived and integrated into velocity and position controllers. Extensive dynamic simulation and experimental verification of the proposed LSRM with the novel FDF is proved to give superior performance in this paper. Such high performance capable of meeting vertical elevator applications is demonstrated.

Design and Control of a Linear Propulsion System for an Elevator Using Linear Switched Reluctance Motor Drives

Unlike its rotary counterpart, the linear switched reluctance machine (LSRM) lends itself to double-sided excitation and multiple translator (or "rotor") configurations that can yield high-force density designs suitable for controlled linear motion in hostile environments. This paper presents the particular design of a 6:4, double-sided, double-translator LSRM that develops 5.1 lb/in/sup 2/ of air gap force shear. The work develops a permeance tube based method to allow simple algebraic magnetic circuit analysis and associated prediction of flux linkages regardless of the level of magnetic saturation of the ferromagnetic structure. Theoretical static thrust predictions are made based on the calculation of change in stored magnetic coenergy per unit distance of translator movement. Laboratory testing of a proof-of-principle LSRM, built up to verify the theoretical predictions, shows that the calculated and measured average thrust values agree within reasonable error over the range of excitation. >

U.S. Deshpande

Papers

A high force density linear switched reluctance machine