Voltage peaks of low voltage induction motors due to PWM inverter supply

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The presence of oil in domestic heat pumps is a hindrance, particularly for enhanced surface evaporators and for advanced concepts based on two-stage cycles. Very compact oil-free dynamic compressor directly driven by high speed electric motors and supported on refrigerant vapor bearings represent a promising alternative. This paper presents a design analysis of the first stage prototype with the various tradeoffs between the impeller characteristics to follow the seasonable heat demand, the bearing and rot

This paper describes a new method to estimate the standstill position of Permanent Magnet Synchronous Motors (PMSM). The method is based on the anisotropic properties of permanent magnets and is therefore referred to as Magnetic Anisotropy Method (MAM). The MAM method differs significantly from all standard standstill position detection methods previously presented in the literature. The proposed method is totally independent of saliency and saturation effects and can therefore be used in many types of PMSM

Swissmetro is a MAGLEV Project between the main cities of Switzerland, designed for a speed up to 500 [km/h] in two tunnels under partial vacuum. Two propulsion variants are considered: - the short stators of the linear homopolar motors are fixed with the tunnel tracks; - the stator of the motors is on board of the vehicles. The levitation, the guidance and the transfer of energy are independent. The authors investigate the possibilities to combine the propulsion with the levitation and the guidance. Polari

The analysis of the dynamic behavior of power transmission line and telecommunication towers is of interest in protection and EMC studies related to lightning. Usually, time-domain surge impedance is used to characterize tower dynamic behavior. The main drawback in the definition of such surge impedance is that it is dependent on the excitation waveshape and there is no consensus on the current waveshape to be used. Also, there is no consensus on the unique definition of the involved voltage. This paper exp

In this paper a polarimetric fibre-optics current sensor in a new highly versatile all-fibre configuration is described. The optical configuration is particularly simple and is based on a back-and-forth propagation through a twisted sensing fibre. This results in a very flexible sensing cable which can be adapted to a great number of existing power installations, by simply winding the fibre around the uninterrupted electrical conductor. The prototype presented here is designed to measure ac and dc currents

The attention of the fusion magnet specialists has been drawn in the last years to the volt-ampere characteristic (VAC) of the large cable-in-conduit conductors (CICC), as early voltage was observed in conductor and model coil tests, far away from the expected critical current. In this paper, the studies and models developed in the last decades for the VAC of bulk material and multifilament strands are shortly reviewed. The practical role of the index n of the VAC, both at the industry and in the magnet des

The current repartition inside a HTS cable is very important for determining its AC losses and can be influenced by the uniformity of several parameters, either linked to the physical properties of the individual tapes (critical current Ic and power index n) or due to the manufacturing process (contact resistance). This work investigates the importance of the non-uniformity of these parameters for a manufactured 16-tape straight superconducting cable by means of finite element method (FEM) simulations. The

The paper describes a modeling tool for the design of a new air-cored current transformer called PRiME (planar Rogowski current measurement) designed on a printed-circuit board (PCB) with the coil made of the PCB printed copper layers. The PRiME technology discussed in this paper exhibits a very original way of getting an efficient external field rejection, allowing the design of air-cored transducers with remarkable overall performances. A theoretical model of the PRiME transducer is presented. The model p

This paper highlights some effects of an asymmetrical design on three phase multilevel inverters from a supply network point of view. The investigated topology is based on a series connection of single phase inverters (partial cell) in each phase. Each partial cell is fed through a three-phase diode rectifier for a unidirectional power flow, fed itself through the secondary of the power transformer (PT). From analytical relationships in continuous and discontinuous current conduction mode, it’s shown that a

Power line communication (PLC) is a well-known technique for data transmission over low-voltage power lines. The PLC signals have frequency bandwidth of about 1-30 MHz and they may cause electromagnetic interferences with services operating in the same frequency range. The regulation of electromagnetic radiation from PLC signals is currently subject of investigation in various international standardization bodies. This paper proposes a technique aiming at reducing the electromagnetic field radiated by indoo

In current tokamaks and, in particular, in future larger devices such as ITER, the control of neo-classical tearing modes (NTM) is essential for achieving high performance in terms of the beta limit. A commonly used scheme for NTM stabilization consists in driving a helical current at the resonance surface of interest with electron-cyclotron-current-drive. Depending on the ratio between the magnetic island size and the RF beam width, complete stabilization of the NTM will only be achieved with deep RF power

In typical power applications, Bi-2223 conductors carrying ac current will be subjected to external magnetic fields, whose orientation and conductor’s geometry are of major significance for the ac loss magnitude. This paper investigates the influence of the geometry and aspect ratio of non-twisted Bi-2223 conductors in reducing the ac loss for such applications. A numerical model of high-Tc materials has been used in finite-element-method simulations. The model incorporates power-law E-J characteristics wit

Voltage peaks of low voltage induction motors due to PWM inverter supply

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High-Speed Low Power Radial Turbocompressor For Oil-Free Heatpumps

A new standstill position detection technique for non-salient PMSM's using the Magnetic Anisotropy Method (MAM)

SWISSMETRO: Combined Propulsion with Levitation and Guidance

On tower impedances for transient analysis

A novel all-fibre configuration for a flexible polarimetric current sensor

The index n of the voltage-current curve, in the characterization and specification of technical superconductors

Numerical modelling of a HTS cable in AC regime

Design of a new air-cored current transformer: analytical modeling and experimental validation

Multilevel Inverter for Power System Applications : Highlighting Asymmetric Design Effects form a Supply Network Point of View

Mitigation of electromagnetic field radiated by PLC systems in indoor environment

Power modulation capabilities of the 140 GHz/1 MW gyrotron for the stellarator Wendelstein 7-X

Geometry considerations for use of Bi-2223/Ag tapes and wires with different models of Jc(B)