Andrzej Marian Pawlak

Electromagnetically controlled heart valve

An electromagnetically controlled artificial heart valve is presented both analytically and experimentally. A mathematical model, based on finite-element analysis, was used to analyze electromagnetic forces exerted on the movable permanent magnet attached to the heart valve. The electromagnetically controlled heart valve configuration represents a new family of electromagnetic devices and is based on a concept where an electronically controlled electromagnetic field controls the valve position. A parametric study was conducted to optimize the heart valve geometry and performance to meet requirements. Prototype units of the optimized structure were successfully built and tested.<<ETX>>

Magnetic velocity sensors

Variable-reluctance devices sense variations in flux linkage while semiconductors read variations in local flux density. The authors show how recognizing this fundamental difference leads to markedly different sensor design approaches, and propose new configurations with improved performance. The analysis of the sensors is based on a general theory developed for these sensors. The magnetic field computations use the finite-element method, which is particularly well suited to this problem involving complex airgap configurations and a need for the calculation of local flux densities and flux linkages.<<ETX>>

Magnets in modern rotary actuators

The principle of operation of most modern rotary actuators is based on permanent magnet-electromagnet interaction to develop electromagnetic torque with limited rotary motion. Because of their simplicity, low cost, and high performance they are finding more and more industrial applications. This paper describes permanent magnet aspects applied to three basic rotary actuator configurations: disc, cylindrical, and claw pole. Although different in shape and magnetization pattern, all magnets feature multipolar structures and are based on high energy magnet materials. Because of the complicated, nonsymmetrical rotary actuator configurations, the magnetic analysis is based on finite element math models. The analysis, which is well supported by test results, is utilized for optimization and parametric study purposes. As a result of our efforts, three different magnet geometries were obtained having different magnetization patterns, which might be applicable for other electromagnetic devices.

A method for determining the field shape influence upon parameters of a DC micromotor

ABSTRACT A method for determining the magnetic field shape influence upon the average values and ripple content in induced voltage, current and the electromagnetic torque of a dc micromotor is presented. The dc micromotor with three slots and six different field shapes is analyzed and described analytically. The analysis shows that by using a shape function X(θ) one can find the best motor performance, i.e., highest average values of torque and the lowest ripple component. Using this approach a rectangular magnetic field shape provides the optimum solution for a wide range of tolerances. With this waveform the motor has no ripple on the induced voltage and as a result the torque pulsation are eliminated.