In this paper, a simple modeling approach on 3D-FEA of hybrid stepping motors taking account of inter-lamination gap is presented. The inter-lamination gap is considered by the reluctance-based cross lamination model which gives the equivalent B-μ data in the direction perpendicular to the lamination used for 3D-FEA. The proposed approach is easily implemented without any penalties such as an increase in the number of elements or the computation time. The effectiveness of the proposed modeling approach is examined by the comparisons between the experimental and the calculated torque characteristics using two hybrid stepping motors with Alnico and thin rare earth magnets respectively. (6 pages)

Hybrid stepping motors derive their name from the fact that their construction is a hybrid between permanent magnet and reluctance motor topologies. Their inherent positional accuracy makes them suitable for a wide range of motion control and industrial positioning applications. This article explains the construction and operation of the hybrid stepping motor. Power converter topologies are presented which are commonly used in hybrid stepping motor drives. Methods are discussed of enhancing performance beyond that achievable by traditional methods. It is shown that the fall in cost of power electronic devices is enabling further enhancements of stepping motor drive technology, broadening the range of applications for this class of motor.

An entirely new class of dual voltage switched reluctance drives is presented. New power converter circuits are introduced, which allow a switched reluctance motor to operate from either an AC mains or a battery supply, with minimal extra power semiconductor components and no extra transformer. Battery charging is achieved without additional components. These converters offer considerable cost savings and flexibility when compared with conventional solutions to the problem of creating a system that can operate from both AC mains supply and battery.

Switched reluctance motors are relatively inexpensive and robust. Especially for lower power drives, the proportional cost of the power electronics is large. It is therefore important to optimise the power converter for each particular application. This paper presents a selection guide and an overview of power electronic converters for single-phase switched reluctance drives.

The paper describes a pulse width modulation (PWM)-controlled series compensator with continuously variable reactance, employing simple PWM duty ratio control. Each phase of the compensator comprises a switched reactor and parallel capacitor. The duty ratio control gives a wide range of capacitive and inductive compensation. The harmonics created by the switched reactor have been analysed. The switched reactor and parallel capacitor have been simulated with a range of switching frequencies and duty ratios. With appropriate choice of capacitor and reactor, a scaled-down experimental model of the compensator has been simulated and constructed. The harmonics have been found to be small even with the switching frequency of the controlled turn-off switches as low as 400 Hz. A large step change in duty ratio from maximum capacitive compensation to inductive compensation shows the rapid dynamic response of the compensator with a fast settling time. This demonstrates that the proposed compensator should be considered as another useful FACTS controller for series compensation.

This paper describes an experimental study undertaken to investigate the vibration induced in the stator of a switched reluctance sector motor. The mechanical response of the stator whilst the motor is stationary and rotating are described. The implementation and effect of a control strategy designed to minimise stator vibration in switched reluctance motors are also presented.

A new PWM controlled series compensator (PWM-CSC) is described which provides adjustable capacitive compensation for power system load flow and receiving end voltage improvement. An experimental single phase radial feed transmission line model has been constructed, using MOS-controlled thyristors. The compensator exhibits a very low level of low order, receiving end voltage harmonic components and minimal transmission line current harmonics are generated into the power system. The PWM-CSC can also provide vernior inductive compensation. The transient response to a step change is fast which facilitates the damping of a power system oscillation after a disturbance.

This article provides an overview of switched reluctance drive technology to date. The operation of the switched reluctance motor is briefly described and basic modelling considerations are presented. Power converter topologies that have been developed for the switched reluctance drive are reviewed. Different switched reluctance motor structures are subsequently described and their main advantages and shortcomings are given. The wide variety of switched reluctance motor and drive topologies illustrates the flexibility of this technology for a wide range of applications.

This paper describes the electromagnetic design, construction and testing of a prototype 5-phase switched reluctance motor that exploits the short flux path concept. If the phase windings are arranged so that neighbouring poles have opposite magnetic polarity then the B-field associated with any two consecutive phase windings forms a short flux loop linking adjacent excited stator poles via the rotor teeth. The MMF required to produce a given flux in the airgap is reduced, resulting in a drop in copper losses. Furthermore, the volume of iron in which hysteresis and eddy current losses are generated is reduced, thus resulting in a drop in iron losses. This paper reviews aspects of the 5-phase motor design, dynamic simulation and construction. Test results from a prototype drive rated at over 4 kW are given.

Electrically powered thruster units are widely used for the propulsion of a variety of small vessels. In craft powered this way, one or more thrusters mounted externally to the vessel are employed to provide both propulsion and a means of steering. This paper describes some of the aspects of the design of a prototype switched reluctance motor for use in an integrated motor/propeller unit. The motor is a three phase sector design with a six pole stator and twenty pole rotor. The paper addresses the factors which influenced the choice of phase and pole numbers and considers some of the trade-offs between the mechanical and electromagnetic requirements. Motor control is also discussed.