Mutual Magnetic Coupling Research Articles

Study on Winding Design of Dual Three-Phase Electrical Machines for Circulating Current Harmonics and Vibration Suppression

The dual three-phase electrical machines (DTP-EMs) have significant advantages and application potential in large-power and high reliability electromagnetic drive system. Nevertheless, one of the main operating challenges of DTP-EMs is the significant high-frequency circulating current harmonics when supplied with voltage-source inverters (VSIs), which will bring unexpected vibration and loss. This paper provides a thorough study on the mutual magnetic coupling effect and design criterion of dual three-phase winding. First, the mathematical model of DTP-EMs is established. Then, the internal mechanism of mutual magnetic coupling and the relationship among the mutual leakage inductance in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$x$</tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$y$</tex-math></inline-formula> subspace, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha$</tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\beta$</tex-math></inline-formula> subspace and stator leakage inductance is revealed. Furthermore, the winding design criterion for DTP-EMs considering high-frequency circulating current harmonics and vibration suppression is proposed. It is drawn that full pitch is required for DTP-EMs to minimize the high-frequency current harmonics and vibration. Finally, two prototypes of the DTP-EM are built and tested to validate the theoretical analysis. This paper provides an effective winding design guide of DTP-EMs for the high-frequency current harmonics suppression and can also be expand to other multi-phase machines.

SIMULATION AND EXPERIMENTAL INVESTIGATION OF DUAL THREE-PHASE BLDC MOTOR OPERATION AT IMBALANCED MODULAR LOADING

Electric machines built according to the modular principle – with several three-phase windings on a stator – are a new direction of modern electromechanics, because they have a number of advantages compared to traditional single-winding machines. Among these benefits, the most important are increased efficiency and fault tolerance, which is especially important for self-powered electric vehicles. However, the presence of a mutual magnetic coupling between the modules, as well as their unequal electrical load, amplify the electromagnetic torque ripple inherent in one or another electric drive system. In this work, the electromagnetic torque ripples in a dual three-phase (DTP) brushless DC motor (BLDCM) under different loads of its modules were investigated for the cases of absence and presence of mutual magnetic coupling between armature winding sets and in the cases of the drive operation in open and closed control systems. The research was carried out by means of simulation in the Matlab/Simulink environment on a circular model of real mock-up sample of DTP permanent magnet machine developed based on the results of its magnetic field simulation using the finite element method. Adequacy of simulation results is confirmed by experimental investigation. The results of the DTP BLDCM simulation studies showed an increase in the relative electromagnetic torque ripples of individual modules due to both the presence of magnetic coupling between winding sets and the deviation from their equal loading. However, at the level of the whole DTP BLDCM, a significant mutual compensation the electromagnetic torque ripples of the modules is shown, especially if they are magnetically coupled. The presence of closed-loop control systems of individual modules significantly reduces the electromagnetic torque ripples caused by different loading of the modules, especially in the case of magnetically uncoupled modules. References 26, figures 7, tables 3.

A 0.7-V Sub-mW Type-II Phase-Tracking Bluetooth Low Energy Receiver in 28-nm CMOS

We present an architecture of a Bluetooth low energy (BLE)-compliant receiver which, for the first time ever, breaks the 1mW barrier of power consumption. It is based on a type-II phase-tracking loop and addresses the mutual magnetic coupling between on-chip inductors of a digitally controller oscillator (DCO) and low-noise transconductance amplifier (LNTA), which causes RX performance degradation in the prior-art implementations. An inverter-based inductor-free LNTA is employed instead. The resulting adjacent channel rejection (ACR) improves by 1.5/2.5dB at 2/3MHz offset. By further leveraging current-reuse and switched-capacitor circuitry, this RX achieves the best-in-class FoM of 183.2dB with sensitivity of -93.2dBm. Thanks to the single-channel topology, the proposed RX occupies tiny area of 0.48mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in 28-nm CMOS.

Preliminary studies for the conceptual design of the quench detection system for the DTT TF superconducting magnets

Abstract The superconducting DTT magnetic system needs a quench detection systems (QDSs) fast enough to trigger the dumping of the magnetic energy in case of quench and avoid irreversible damage of the cable systems. With this aim, a primary system based on the detection of the resistive voltage associated with the quench offers the best quench detection guarantees. The tokamak environment is affected by several electromagnetic noises during plasma scenarios so that the resistive voltage detection, during normal operation, can be compromised by the presence of large voltages induced by self and mutual magnetic coupling among coils and with plasma or passive elements: the resulting inductive voltages across a TF coil, or part thereof, could be much higher than the quench voltage thresholds. Voltage compensations techniques, therefore, have necessarily to be foreseen in the QDSs conceptual design, to discriminate the resistive component associated with the quench. We present a reconnaissance of all known electromagnetic noises that could affect a TF coils QDS in DTT: this analysis is conducted by means of analytical calculations, made up with the aim to evaluate and have a prevision of the maximum extent of the voltages induced across TF coils and Double Pancakes (DPs) during, in particular, the Single Null (SN) scenario.

Three-dimensional radio-frequency transformers based on a self-rolled-up membrane platform

Radio-frequency (RF) integrated circuits are used for wireless communications and require transformers capable of transferring electrical energy at RF/microwave frequencies. Traditional on-chip RF transformer designs have complex fabrication schemes and offer limited performance scalability. Here we report on-chip RF/microwave transformers that are based on a self-rolled-up membrane platform. The monolithic nature and versatility of this platform allows us to create high-performance transformers while maintaining an ultra-compact device footprint and by using only planar processing. We also show that the performance of the three-dimensional RF transformers improves with scaling, which is in contrast to conventional planar designs. In particular, we observe a continuous rate of increase in the index of performance of our RF transformers as we scale up the turns ratio. This behaviour is attributed to the almost ideal mutual magnetic coupling inherent to the self-rolled-up membrane three-dimensional architecture.

Design Analysis of a Dual Rotor Permanent Magnet Machine driven Electric Vehicle

Electric bike in urban countries such as Europe and China commonly used the brushless direct current machine (BLDC) as it able to produce high torque to transport the user from one place to another. However, BLDC torque density can’t be improving due to limitation magnetic flux generated by the permanent magnet. Therefore, the performance of electric bike can’t be improved. Outer rotor BLDC machine design able to improve the torque density of the motor due to increase radius of the motor which can be explained by simple physics equation (Torque = Force x radius). However, an outer rotor machine only generates constant speed, which is not suitable for operating under tractive load condition, especially electric bike. The proposed model is a new novel of double layer outer rotor BLDCPM machine which able to amplify the magnetic flux density and improve the torque density of the machine. The mutual magnetic coupling between the inner and outer rotor of the proposed model increase the magnetic flux intensity as both of them acts as individual parts. Thus, the magnetic flux generated by both rotors are double which resulted in improving the performance of the E-bike. Designing parameters and analysing the performance of the proposed 2D model is done using FEA tools. Evaluation of the conventional and proposed model by comparing torque performance, magnetic flux density and motor constant square density. Other than that, speed torque graph also is evaluated to justify either it can operate similarly to ICE engine with gears. Two model is designed which is Single Outer Rotor Brushless Direct Current (SORBLDC) and Double Outer Rotor Brushless Direct Current (DORBLDC) operated with the same cases of 27 Amp current supplied to it and operate under various speed from 500 rpm to 2000 rpm. The average torque produce by the conventional and proposed model are 2.045439 Nm and 3.102648 Nm. Furthermore, improvement of the proposed model to conventional model in terms of motor constant square density by 24.92%. Therefore, the proposed model able to improve the magnetic flux by amplifying which resulted to increase the torque density of the machine. Furthermore, the speed-torque graph of the proposed machine shows similarity with speed torque graph of ICE engine. Thus, the proposed machine is suitable to operate for bike application

Quantification of Magnetic Field Compatibility of Subcomponents in an MRI-Guided Radiation Therapy System

An MR-guided radiation therapy (MRgRT) system, consisting of a 6X linac and a 1.5 T MRI scanner-on-rails is under development at our institution. The MR can travel into the linac vault and image in the proximity of the linac, while the linac is in stand-by behind RF doors. A modified robotic patient table can move between the MR isocenter (goal: imaging) and linac isocenter (goal: imaging and treatment delivery). The study investigated the degree of mutual magnetic coupling between the linac/table subsystems and the MR's magnetic field.

A New Zone-Control Induction Heating System Using Multiple Inverter Units Applicable Under Mutual Magnetic Coupling Conditions

This paper proposes a new “zone-control induction heating” (ZCIH) system consisting of two or more sets of a high-frequency inverter unit and a work coil. The work coils are wound around a single susceptor as close as possible to reduce a leakage magnetic flux. The inverters independently control the amplitude of each coil current to adjust the power provided to the work coil and/or the heat generated in each zone of the susceptor. As a result, the ZCIH system enables a temperature uniformity not only in a heating-up period but also in a temperature-maintaining period. Theoretical analysis derives the control performance of the current amplitude, and implies that the phase-angle control of the coil current is required to adjust the current amplitude in a wide range. This paper presents experimental results obtained from a laboratory setup and a six-zone prototype for semiconductor processing.

Numerical investigations of the mutual magnetic coupling in superconducting tapes in z-stack arrangement with external AC magnetic field

Numerical studies of the mutual magnetic coupling in superconducting tapes arranged in stacks with different number of tapes and at different distances between them are presented. Constant critical current density (independent on the magnetic field strength) and power law E– J characteristic are assumed. The influence of the coupling `strength' on AC susceptibility, and AC losses is investigated. Transition from `single block' at zero distance between tapes down to `single tape' behavior at larger distances is evident.

New power transformer model for the calculation of electromagnetic resonant transient phenomena including frequency-dependent losses

A new power transformer model for the accurate predetermination of transient resonant processes is introduced in this paper. The accurate representation of the losses is the most important feature of the new model since it has been developed for the accurate determination of maximal stresses during resonance phenomena within transformers. The new equivalent circuit only contains constant lumped parameters. It represents very accurately the frequency variation of all impedances (real and imaginary parts) of the transformer, including mutual magnetic coupling. This allows carrying out transient calculations in the time domain directly using programs for the electromagnetic transients calculations like EMTP. Several laboratory measurements on transformer winding models have been performed in order to verify the agreement of measured and calculated values of resonant overvoltages.

4751464 Cavity resonator with improved magnetic field uniformity for high frequency operation and reduced dielectric heating in NMR imaging devices

A cavity resonator suitable for use in a high-speed nuclear magnetic resonance (NMR) imaging device comprises a plurality of transmission lines aligned parallel to a common axis and magnetically coupled to produce an essentially uniform dipole magnetic field perpendicular to the axis. The transmission lines are two conductor lines, with the first conductors being arranged inwardly of a second conductor common to all lines. The common conductor is symmetrically arranged about the axis of the resonator and constitutes a shield to contain the magnetic field within the cavity. The plurality of transmission lines are conductively isolated from each other but spaced in sufficiently close proximity to each to provide for strong mutual magnetic coupling amongst all transmission lines. A single inductive coupling loop may be provided for driving the resonator with a linearly polarized magnetic field and for receiving NMR information from the resonator. The use of a pair of inductive coupling loops spaced 90° about the resonator axis provides a circularly polarized magnetic field within the resonator when the loops are driven in electrical phase quadrature. Two inductive coupling loops for each imaging mode may be provided to eleminate undesirable modes and hence distortion in the NMR image. The common conductor and the longitudinal ends of the resonator are provided with slits designed to allow the changing high-speed gradient magnetic fields to fill the imaging volume fast enough to accomplish high-speed imaging.