Electromagnetic fields and interactions in 3D cylindrical structures : modeling and application

The demand for more efficient and compact actuation systems results in a search for new electromagnetic actuator configurations. To obtain actuators that meet these challenging specifications, accurate modeling of the electromagnetic fields is often a prerequisite. To date, analytical modeling techniques are widely used to predict electromagnetic fields in classical rotary and linear machines represented in two dimensional coordinate systems. This thesis presents the extension of an analytical modeling technique to predict the 3D field distribution in new cylindrical actuator configurations. One specific technique that is used to analyze and design electromagnetic devices is based on Fourier series to describe sources and the resultingmagnetic fields. In this research, the harmonic modeling technique is extended to describe electromagnetic fields due to presence of permanent magnets in regular and irregular shaped 3D cylindrical structures. The researched modeling technique can be applied to current-free cylindrical problems exhibiting periodicity or a soft-magnetic boundary in the axial direction. The cylindrical structure can posses either circumferential slots, axial slots or rectangular cavities. The assignment and a method to solve the various boundary conditions are discussed in a generic manner to enable model application to a wide range of 3D cylindrical structures. The magnetic field solutions are provided, and the model implementation is presented in matrix form. Model validation is presented by means of a comparison of the magnetic fields in a cylindrical structure with a rectangular cavity calculated using the analytical model and a finite element model. To calculate the magnetic interactions, e.g., attraction and cogging forces due to permanent magnets, the Maxwell stress tensor is analytically evaluated. The harmonic magnetic field solution is used in this evaluation resulting in compact force equations describing the 3D force components between concentric cylinders

A football kicking high speed actuator for a mobile robotic application

This paper presents the design and validation of a high speed reluctance actuator for a soccer robot. The actuator is used to shoot a regular sized soccer ball by applying different force levels directly to the ball. As the application requires force in only one direction, a plunger type reluctance actuator is selected. A capacitor is used to buffer energy from the battery of the robot. Through an IGBT, the energy is transferred from the capacitor to the actuator. Consequently, by applying pulse width modulation, the force applied by the actuator can be adjusted to enable a variable shooting power. The reluctance type actuator is designed using finite element analysis. The actuator is build and implemented in the robot providing the capability to shoot a ball from standstill over 12 meters with a starting speed of 11 m/s

Novel moving coil tubular actuator with double sided PM array

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Influence of multiple air gaps on the performance of electrical machines with (semi) Halbach magnetization

The ever increasing necessity to improve torque density while simultaneously maintaining high efficiency is a constant point of concern for electrical machine designers. This is mainly driven by the need for direct-drive solutions in evermore applications. This paper presents a general mesh-free description of the magnetic field distribution in multiple air-gap electromagnetic machines, although the tool is also useful for single air-gap machines, actuators, and other magnetic devices. The used method is based on transfer relations and Fourier theory, which can provide the magnetic field solution for a wide class of 2-D boundary value problems. This technique is in this paper applied to the rotary multiple air-gap machine with slotless (without slots but with and without rotor back-iron) armature. The presented analysis is compared to finite-element analysis for the multiple-layer winding, which shows the applicability of this method for future optimization. It is shown that multiple air-gap machines make better use of the volume and for short axial lengths where a single-side bearing configuration can be utilized provides a means to improve the achievable torque density

Moving device as well as a component placement device provided with such a moving device

Samenvatting van US 2011194923 (A1) A moving device comprises at least a first element provided with main magnets and a second element provided with coils. The main magnets are arranged in a grid of rows and columns, wherein main magnets in adjacent rows are oppositely polarised and staggered relative to each other. The coils can be energized for moving the first element relative to the second element in a direction parallel to the rows as well as in a direction parallel to the columns. Auxiliary magnets of the same polarity are disposed between the main magnets at least in a number of rows, wherein the strength of the magnetic field of said auxiliary magnets is different from that of the main magnets

Modeling and experimental verification of a tubular actuator for 20 g acceleration in a pick and place application

This paper presents the modeling and the experimental verification of a tubular actuator for a pick and place application. To increase the throughput of a placement robot for printed circuit boards, very fast linear motion is required. A moving magnet tubular actuator with axially magnetized magnets is selected. Using a semi-analytical magnetic field description coupled to thermal models, a design is created that potentially could achieve a translator acceleration of 20 g. A prototype of the designed actuator is built and coupled with a Simulink dSpace system to perform extensive measurements to validate the models and investigate the achievable acceleration within a pre-determined motion profile. The electro-motive force is measured, and the disturbance forces are identified. The position error is measured during the motion profile with an acceleration of 20 g and a stroke of 30 mm. Furthermore, thermal measurements are performed to check the achievable duty cycle. The built design shows good agreement with the models, and the specified acceleration of 20 g is achieved

Static coupling effect of a two-degree-of-freedom direct drive induction motor

Two-degree-of-freedom motors are capable of producing linear, rotary, and helical motion, and thus have widespread applications in special industries. In this study, a new concept- static coupling effect is studied in the two-degree-of-freedom direct-drive induction motor (2DoFDDIM). The proposed approach is based on the image method and the three-dimensional (3D) finite-element method. The image method model is established to analyse its reasons and predict the main effects, which are then verified by the proposed 3D finite-element static coupling model and experiments. The induced voltages and currents are produced in the static part and induced torque or force is obtained, even though the static part is not energised. It is concluded that the static coupling effect increases with the supply frequency and is influenced by the stator winding configuration. Thus, the existence of the static coupling effect is confirmed, which must be taken into account in future optimisation and precise control of the 2DoFDDIM