Jan Jozef Rens

A Novel “Pseudo” Direct-Drive Brushless Permanent Magnet Machine

For low-speed electrical machine applications, it is usually weight/size and cost effective to employ a high-speed machine together with a mechanical gearbox. However, the disadvantages associated with magnetic gearboxes can be overcome by mechanically and magnetically integrating a magnetic gear and a permanent magnet brushless machine, to create a ldquopseudordquo direct-drive machine. It is shown that a torque density in excess of 60 kNm/m 3 can then be achieved, at a power factor in excess of 0.9.

A Novel Magnetic Harmonic Gear

Magnetic gears offer several advantages compared to mechanical gears in terms of reduced maintenance, improved reliability, and inherent overload protection while having a high efficiency. This paper describes the principle of operation of a novel form of magnetic gear, which is particularly suited to applications for which a high gear ratio is required. The performance capability of such a magnetic gear is investigated, and it is shown that it transmits a ripple-free torque and that an active torque density of up to 150 kN · m/m3 per stage can be achieved when high-energy permanent magnets are employed. Simulation results on this novel gear are verified by experimental measurements on a prototype.

Design features for enhancing the performance of electromagnetic valve actuation systems

The paper describes a type of variable air-gap reluctance actuator that offers potential for enhancing the dynamic performance of electromagnetic valve actuation systems for internal combustion engines. In both the stator and armature, the actuator incorporates design features that allow the force-displacement characteristic to be tailored to meet operational requirements. The paper demonstrates the considerable scope for varying actuator characteristics by means of detailed two- and three-dimensional finite-element modeling. The key findings from the finite-element modeling are validated by experimental measurements on a prototype actuator.

A novel magnetic harmonic gear

Magnetic gears offer several advantages compared to mechanical gears, in terms of reduced maintenance, improved reliability and inherent overload protection, whilst having a high efficiency. The paper describes the principle of operation of a novel form of magnetic gear, which is particularly suited to applications for which a high gear ratio is required. The performance capability of such a magnetic gear is investigated, and it is shown that it transmits a ripple-free torque, and that a torque density of up to 110 kNm/m can be achieved when high- energy permanent magnets are employed.

Design, analysis and realization of a novel magnetic harmonic gear

High performance magnetic gears are competitive with mechanical gears in terms of their torque transmission capability, and they offer significant operational benefits. Various topologies of magnetic gear have been developed, the one which is described in this paper being particularly appropriate for use in applications for which a high gear ratio is required. It is the magnetic equivalent of a mechanical harmonic gear, and can transmit ripple-free torque at a torque density of up to ~110 kNm/m3 when high energy permanent magnets are employed. The paper will describe the operating principle, design and analysis of a harmonic magnetic gear, including a dual-stage configuration which enables much higher gear ratios to be achieved. Finally, the practical realization of such a magnetic gear will be described.

Static Performance of a Polarized Permanent-Magnet Reluctance Actuator for Internal Combustion Engine Valve Actuation

This paper describes the topology of a permanent-magnet polarized reluctance actuator that enhances the performance of electromagnetic valve actuation systems; specifically, it reduces losses during extended periods of valve closure, improves controllability, provides a degree of fail-safe operation in the event of a system fault, and reduces currents required for system initiation during cold-starting of the engine. The paper describes the basic operating mechanism of the actuator and explains the influence of various design features on its static characteristics by means of a finite-element-based design study on a representative performance specification. A prototype device has been manufactured and its static characteristics have been measured experimentally to illustrate the utility of the proposed actuator topology and the key findings from the design study.

Enhancing the force capability of permanent magnet latching actuators for electromechanical valve actuation systems

This article introduces a topology of parallel-polarized permanent magnet latching actuator for use in electromagnetic valve actuation systems for internal combustion engines. The actuator has a number of advantages over reluctance actuators, commonly employed in such systems, in terms of reduced starting currents and fail-safe capability. The influence of a number of design features on actuator performance, such as tooth tapering, additional magnets to improve the main magnet flux path and prevent the onset of saturation, and mechanical clearances required to protect the permanent magnet from shock loads are investigated. The design study findings are verified by measurements on a prototype actuator.

Effects of cutting and annealing of amorphous materials for high speed permanent magnet machines

When using amorphous material in an electric motor, the losses are often higher than expected. This paper investigates the effect of cutting and annealing on the performance of amorphous material. The BH-curve and losses are compared before and after an annealing treatment. Furthermore, the properties are compared for material cut with a plate shear and cut by laser, followed by an annealing treatment. A case study is done for a high speed motor, comparing the amorphous material with a conventional silicon steel grade. Based on a FEM analysis, a reduction of iron loss by a factor 7 is found through the use of an amorphous material instead of a conventional silicon steel.