Nady Boules

Prediction of No-Load Flux Density Distribution in Permanent Magnet Machines

Both the average output torque as well as the output torque pulsations of permanent magnet (PM) motors depend on the air gap flux density waveform produced by the magnets. An analytical model is presented, which uses the two-dimensional field theory in polar coordinates to determine the flux density waveforms at the stator and rotor surfaces of PM machines and also the amount of magnetic flux entering these surfaces. The analysis is valid for dc as well as for synchronous brushless motors with magnets which are magnetized in either the radial or the parallel direction. The results obtained by the model are verified by comparison with results obtained by finite-element analysis as well as with test results.

Two-Dimensional Field Analysis of Cylindrical Machines with Permanent Magnet Excitation

The design of the magnetic circuit of permanent magnet machines differs from that of conventional wound field machines mainly due to the low magnetic permeability of the magnets. A two-dimensional field analysis is presented which takes the magnet leakage, the distribution of magnet MMF along its height, and the changing magnet width into consideration. The fundamental component of flux calculated by the model is compared with results obtained by finite element analysis for different magnet configurations covering a practical range of magnet dimensions. A comparison of machine performance predicted using this method with test results is also given.

Design optimization of permanent magnet DC motors

A mathematical model suitable for the design optimization of permanent magnetic (PM) DC motors is presented. The model, which combines the motor electric, magnetic, and physical quantities, takes the armature reaction effects, brush drop characteristics, and magnetic saturation of the iron parts into account. A method for transformation of variables which makes the model applicable to a wide range of motor ratings is presented. The model is utilized in a computer program which systematically determines the optimum design parameters of the motor. The author describes the optimization techniques used and the logical structure of the computer program. A numerical example demonstrating the effectiveness of the program is also given. >

A high-efficiency, high power generation system for automobiles

This paper presents a new scheme for the efficient generation of high electric power demanded for future automobiles. The new system consists of a permanent-magnet (PM) alternator having high-energy MAGNEQUENCH (MQ) magnets and split winding and a novel electronic voltage regulation scheme. A proof-of-concept system, capable of providing 100/250 A (idle/cruising) at 14 V, has been built and tested in the laboratory with encouraging results. This high output is provided at 15-20 percentage points higher efficiencies than conventional automotive alternators, which translates into considerable fuel economy savings. The system is 8 dB quieter and has a rotor inertia of only 2/3 that of an equivalent production alternator, thus allowing for a belt drive without excessive slippage.

Design optimization of glass-embedded capacitive-type water sensors

Capacitors consisting of oppositely charged inductor bars sandwiched between two parallel plates of glass are well suited for applications requiring the detection of water. The sensitivity to water on the glass surface is a complication function of both the geometry and dielectric properties of the sensor and its environment. A closed-form analytical model suitable for use in the optimization of such sensors is presented. The model is successfully applied to the design optimization of an example and is verified using a finite-different model and test results. >