Consideration of array module design for energy harvesting of power-line magnetic noise

ArticleMaterials Science Forum. 721:191-198 (2012)journal articl

Simple-Box-9 Coil System: A Novel Approach to Design of a Square Coil System for Producing Uniform Magnetic Fields

This paper presents a novel approach for the design of square coil system, through considerations of a conventional square coil system. This simple approach allows us to design a coil system which contains a greater number of coils. From this design method, we introduce a new structure system of same-sized square coils, Simple-Box-9. The constant coil spacing is a fourth-part of the side length of the coil, and the number of windings is 2/1/1/1/1/1/1/1/2. From numerical calculations and experiments, it is shown that Simple-Box-9 can achieve the best uniformity compared with conventional square coil systems.ArticleMaterials Science Forum. 670:275-283 (2010)journal articl

Loss measurement in power conditioning module for power-line magnetic noise energy harvesting device

The purpose of our research is to develop an energy harvesting device for a power-line magnetic field of 60 Hz. This device consists of an energy harvesting module and a power conditioning module. The harvesting module can provide 25 mW to an optimum load of 1 kΩ from a field of 45.3 μT. To use the harvested energy as a battery, a power conditioning module consisting of a rectifier circuit and a DC-DC converter is required. We prepared two fullwave rectifier circuits with different Schottky diodes, and an ultralow voltage step-up converter for an output of 5 V. The efficiency of the rectifier circuit was greater than 80 %. It was found that the efficiency of the DC-DC converter depended on the input voltage and the dummy load. From experiments, we successfully demonstrated that our developed harvesting device can provide an output voltage of 5 V. To use this device as a battery, loss in the power conditioning module was also discussed.ArticleJournal of the Japan Society of Applied Electromagnetics and Mechanics. 20(2):440-445 (2012)journal articl

Simple-Box-9 coil system: A novel approachto design of a square coil system for producing uniform magnetic fields

This paper presents a novel approach for the design of square coil system, through considerations of a conventional square coil system. This simple approach allows us to design a coil system which contains a greater number of coils. From this design method, we introduce a new structure system of same-sized square coils, Simple-Box-9. The constant coil spacing is a fourth-part of the side length of the coil, and the number of windings is 2/1/1/1/1/1/1/1/2. From numerical calculations and experiments, it is shown that Simple-Box-9 can achieve the best uniformity compared with conventional square coil systems.ArticleMaterials Science Forum. 670:275-283 (2010)journal articl

Theoretical design of energy harvesting module or wireless power transmission receiver using magnetic field of 0.2 mT at 60 Hz

This paper presents a theoretical design method for a magnetic energy harvesting module. This module consists of an air-core coil and resonant capacitor. With a simple RLC circuit model, it can derive an equation of harvesting energy as a function of coil size. In order to demonstrate the magnetic field, a uniform magnetic field is generated by the developed coil system. From the experimented results, it is successfully demonstrated 100 mW of energy harvesting from a magnetic field of 0.09 mT at 60 Hz. This value is in good agreement with the estimated results. Harvested energy is proportional to the square of the magnetic flux density. However, ICNIRP2010 provides a guideline that an acceptable level for human health in a public space is 0.2 mT at power-line frequency. This paper also discuss the possibilities of several applications related with both magnetic energy harvesting and wireless power transmission.ArticleJournal of Energy and Power Engineering. 7:740-745 (2013)journal articl

Estimation of Effective Permeability for Dumbbell-Shaped Magnetic Cores

The objective of this paper is to provide suitable approximations of effective permeability for magnetic concentration cores. This core has a dumbbell shape so that the magnetic flux is concentrated to the coil winding part of the core. It is well known that the demagnetizing factor strongly depends on the core shape, which defines the effective permeability. Although several researchers have already proposed an approximation for a dumbbell-shaped core, they did not take into account the flange part length. In this paper, a novel approximation for a dumbbell-shaped core is proposed. It is based on the demagnetizing factor and correction terms related to the aspect ratio of both the flange and coil winding part. From experimental results, the validity of the approximation is confirmed.ArticleIEEE TRANSACTIONS ON MAGNETICS. 51(1):4000304 (2015)journal articl

Preliminary study of MCG measurement with induction gradiometer

The purpose of our study is to demonstrate magnetocardiography (MCG) measurements from a human heart using our developed induction gradiometer. We have already reported the capabilities of our gradiometer, whose sensitivity at low frequency is comparable to that of a commercial SQUID sensor. However, we could not observe magnetic fields less than 1 nT because of electrical interference at the gradiometer. We solved this problem using a grounding technique and re-designed electronics. We modeled an MCG signal generated by PC-based instrumentation using LabVIEW software, and a magnetic field was generated with a one-turn coil. In order to generate an MCG field with an R-wave peak amplitude 100 pTp-p, we estimated the required current value for the one-turn coil. The experimental results obtained in our laboratory environment, we confirmed the observation of the R-wave with the induction gradiometer.ArticleJournal of the Japan Society of Applied Electromagnetics and Mechanics. 20(2):453-458 (2012)journal articl

Desktop Magnetic Shielding System for the Calibration of High-Sensitivity Magnetometers

The objective of the study is a development of desk-top magnetic shielding system for the calibration of high-sensitive magnetometers, and the evaluation of their ability to produce a uniform magnetic field. This system consists of hexagonal tubes and a cylinder. The hexagonal tubes have a double-layered structure, an opening and an advantage in axial shielding performance. The cylinder has openings and an advantage in transverse shielding performance. A solenoid-like coil is wound around the hexagonal tubes to produce a uniform magnetic field. From the experimental results, the magnetic shielding and the calibration field properties are demonstrated. Within the half length of the system, the achieved total magnetic field (dc component) is less than 200 nT within ± 50 nT deviation, and the measured shielding factor is larger than 250. For producing a uniform magnetic field up to 10 kHz, we can use the 1/3 length of the system.ArticleIEEE TRANSACTIONS ON MAGNETICS. 47(10):4270-4273 (2011)journal articl

Double side interior permanent magnet linear synchronous motor and drive system

Linear motor has been applied in various fields such as factory and office automation. A linear motor differs from a rotational motor, in which it has a simpler structure. Linear Synchronous Motor is one of the types of linear motor and its application is very wide which is from the small application (i.e. industrials automation) to large application (i.e. maglev transportation) [1]. The thrust which is generated by linear motor is high, even with the size of the motor is small [2]. This is the feature of the linear motor compared to rotational motor where a gear is needed to change the rotational movement to the linear movement. Therefore the linear motor can reduce the mechanical losses. This paper discuss on the proposal of Double Side Interior Permanent Magnet of Linear Synchronous Motor (DIPM-LSM). The structure and three dimensions of magnetic circuit of DIPM-LSM are discussed. This type of DIPM-LSM can be driven by sinusoidal and pulse voltage input. The three phase two coils excitation-driving mode of open loop drive systems are also been discussed

An Experimental Study of Stable Operating Conditions for a High-Sensitivity Induction Gradiometer

Stable operating conditions for a high-sensitivity induction gradiometer are studied experimentally. In order to reduce electrical interferences in our developed induction gradiometer, we construct a Faraday cage. It consists of copper mesh and wood, and is 2.0 m x 1.8 m x 1.8 m in size. Experimental results show that the inside of the cage can provide a quiet electrical environment where the electrical interference is suppressed. Choosing a suitable grounding point for the electronics, undesirable signals in the sensor output are cleaned. Observation of a weak magnetic field is also demonstrated.ArticleIEEE TRANSACTIONS ON MAGNETICS. 45(6):2784-2787 (2009)journal articl