Very High Speed Slotless Permanent Magnet Motors: Analytical Modeling, Optimization, Design and Torque Measurement Methods

This paper presents a very-high-speed (VHS) slotless permanent-magnet motor design procedure using an analytical model. The model is used to design the optimal prototype (target: 200 kr/min, 2 kW). The multiphysics analytical model allows a quick optimization process. The presented model includes the magnetic fields, the mechanical stresses in the rotor, the electromagnetic power losses, the windage power losses, and the power losses in the bearings. VHS machines need a new torque measurement method. This paper presents the developed method. It also presents a ball bearing friction torque measurement method designed particularly for VHS machines. Remarkably, the method allowed us to design a prototype which operates beyond the target of speed and power. The results given by the model are compared with the measurements of the prototype

Force and Torque Analytical Models of a Reaction Sphere Actuator Based on Spherical Harmonic Rotation and Decomposition

This paper presents an analytical model for the force and torque developed by a reaction sphere actuator for satellite attitude control. The reaction sphere is an innovative momentum exchange device consisting of a magnetic bearings spherical rotor that can be electronically accelerated in any direction making all the three axes of stabilized spacecrafts controllable by a unique device. The spherical actuator is composed of an 8-pole permanent magnet spherical rotor and of a 20-coil stator. Force and torque analytical models are derived by solving the Laplace equation and applying the Lorentz force law. The novelty consists in exploiting powerful properties of spherical harmonic functions under rotation to derive closed-form linear expressions of forces and torques for all possible orientations of the rotor. Specifically, the orientation of the rotor is parametrized using seven decomposition coefficients that can be determined noniteratively and in a linear fashion by measuring the radial component of the magnetic flux density from at least seven different locations. Therefore, force and torque models for all possible orientations of the rotor are expressed in closed form as linear combination of mutually orthogonal force and torque characteristic matrices, which are computed offline. The proposed analytical models are experimentally validated using a developed laboratory prototype

Electromagnetic Analysis and Validation of an Ironless Inductive Position Sensor

The ironless inductive position sensor is a linear position sensing structure, which exhibits intrinsic immunity to external magnetic fields since it is characterized by air-cored windings. This new solution may be of major interest for applications where external magnetic fields can be a source of interference. In this paper, an analytical model of the working principle of the sensor is proposed. The effect of the moving coil flux on the overall sensed magnetic flux is described. The model is preliminarily verified by simulations on a finite-element structure of the sensor, in order to assess its soundness. Finally, experimental measurements on a custom sensor's prototype give the definitive benchmarking of the model as a valid design tool, in the framework of the design and synthesis of the device. © 1963-2012 IEEE

The Flavonoid Luteolin Inhibits Fcγ-Dependent Respiratory Burst in Granulocytes, but Not Skin Blistering in a New Model of Pemphigoid in Adult Mice

Bullous pemphigoid is an autoimmune blistering skin disease associated with autoantibodies against the dermal-epidermal junction. Passive transfer of antibodies against BP180/collagen (C) XVII, a major hemidesmosomal pemphigoid antigen, into neonatal mice results in dermal-epidermal separation upon applying gentle pressure to their skin, but not in spontaneous skin blistering. In addition, this neonatal mouse model precludes treatment and observation of diseased animals beyond 2–3 days. Therefore, in the present study we have developed a new disease model in mice reproducing the spontaneous blistering and the chronic course characteristic of the human condition. Adult mice were pre-immunized with rabbit IgG followed by injection of BP180/CXVII rabbit IgG. Mice pre-immunized against rabbit IgG and injected 6 times every second day with the BP180/CXVII-specific antibodies (n = 35) developed spontaneous sustained blistering of the skin, while mice pre-immunized and then treated with normal rabbit IgG (n = 5) did not. Blistering was associated with IgG and complement C3 deposits at the epidermal basement membrane and recruitment of inflammatory cells, and was partly dependent on Ly-6G-positive cells. We further used this new experimental model to investigate the therapeutic potential of luteolin, a plant flavonoid with potent anti-inflammatory and anti-oxidative properties and good safety profile, in experimental BP. Luteolin inhibited the Fcγ-dependent respiratory burst in immune complex-stimulated granulocytes and the autoantibody-induced dermal-epidermal separation in skin cryosections, but was not effective in suppressing the skin blistering in vivo. These studies establish a robust animal model that will be a useful tool for dissecting the mechanisms of blister formation and will facilitate the development of more effective therapeutic strategies for managing pemphigoid diseases

Effect of composite surface treatment and aging on the bond strength between a core build-up composite and a luting agent

Objective The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement. Material and Methods Eighty blocks (8×8×4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5°C and 55°C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mm Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (µTBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5°C and 55°C, with a dwell time of 30 s in each bath) and µTBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (α=0.05). Results The µTBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling. Conclusion Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement

Brushless motor design with global parametric optimization - application to an artificial blood pump

Designing transducers or motors, requires the analysis of a lot of parameters such as length, temperature, efficiency, weight, etc. The solution to obtain the optimum results for given specifications is to analyze globally all the free parameters in one go, with an optimization algorithm based on the "Prodesign" software, including its optimization module, developed by the INPG in Grenoble (France). A general module makes it possible then to get the optimum according to the constraints of the problem. In future, a module for each type of transducer or motor as well as a module for the driver is develope

Reluctance motor and actuator design: Finite-element model versus analytical model

Designing actuators or motors requires analysis of a lot of parameters such as length, temperature, efficiency, and weight. A global analysis to evaluate these parameters is possible. Three methods can be used: 1) an analytical method, allowing parametric study and parameter sensitivity analysis; 2) a finite-element model, which makes it possible to take into account nonlinearities, including the fringe effect; and 3) the analytical method, followed by a process of optimization, which makes it possible to reach an optimum based on an objective function and constraints. This paper describes each of these methodologies and compares them to help designers make a choice. Two examples to illustrate the three methods are a reluctance actuator and a brushless dc motor intended for a new intracardiac blood pump

High series motor or actuator design-finite element model versus analytical model

To design actuators or motors requires analyzing a lot of parameters such as length, temperature, efficiency, weight, etc. To obtain the optimum results for given specifications the solution is to analyze globally all the free parameters in one go, with an optimization algorithm based on the "Prodesign" software which includes an optimization module developed by INPG in Grenoble (France). A comparison between the parametrical study and the finite element design is made with two different examples. The first one is a reluctance actuator and the second one is a brushless DC motor intended for a new intra-cardiac blood pum