Yasunori Kanamaru

A technique for the steady-State analysis of a grid-connected permanent-magnet induction Generator

This paper presents a technique by which the steady-state performance of a grid-connected permanent-magnet induction generator (PMIG) can be predicted more accurately. By applying the topological principle of duality, an equivalent circuit of the PMIG is derived that takes into consideration the core loss as well as the permanent-magnet (PM) excitation. The nonlinear parameters in the equivalent circuit are modeled using curve-fitting methods. Experimental results performed on a 2.2-kW prototype PMIG demonstrate the accuracy of the proposed technique.

Properties of EHD pump with combination of rod-to-rod and meshy parallel plates electrode assemblies

A high pressure required to drive the liquid can be generated by the compact electrohydrodynamic (EHD) pumps with multiple pairs of the rod-to-rod and meshy parallel plates electrode assemblies arranged in series. In this work, the performance of EHD pumps with electrodes up to nine pairs has been examined as a function of the applied voltage using a semi-insulating liquid. The pressure generated by energized electrodes gives rise to the vigorous liquid flow and the liquid ejects from the pump outlet. The flow direction always is from the cathode toward the anode. The pressure increases with nearly the square of the applied voltage and in proportion to the number of electrode pairs. The maximum pressure head achieved with a series of nine electrode pairs is 25.3 kPa at 18 kV with maximum power consumption of 7.2 W. The generated pressure is maintained stably at constant level of the corresponding value. EHD pumping is attributed to conduction pumping based on an unbalance of heterocharges with single ionic polarity in the vicinity of the anode and cathode.

Effects of the Built-in Permanent Magnet Rotor on the Equivalent Circuit Parameters of a Permanent Magnet Induction Generator

The permanent magnet induction generator (PMIG) is a new type of induction generator (IG) that has a permanent magnet (PM) rotor inside a squirrel cage rotor. The squirrel cage rotor is linked to the shaft, and the built-in PM rotor is free to rotate against the shaft. One of the notable features of the PMIG is that the power density is higher compared to a conventional IG. In this paper, the effects of the built-in PM rotor on the equivalent circuit parameters are investigated to clarify the reason for the increased power density.

Creeping discharges in transformer oil under lightning impulse voltages over 100 kV peak value

This paper describes the experimental results on the creeping streamer progressing the surface of a bakelite board immersed in transformer oil under the application of a standard lightning impulse voltage with peak values of plusmn100~350 kV. The growth of streamers is significantly affected by the thickness of bakelite board and the streamers are extended longer exponentially for the applied voltage more than ~plusmn200 kV. These streamers leave the remarkable discharge scars on the bakelite surface. The discharge scars are different by the voltage polarity which influences strongly to the streamer growth. The mean streamer velocities in both polarities have also been examined.

Properties of creeping discharge progressed in narrow gap between two solid dielectrics in PFAE oil

The behaviors of creeping streamers progressed in a narrow gap between two solid dielectric plates immersed in palm fatty acid ester (PFAE) oil have been investigated using ±1.2/50 µs and ±1.2/1000 µs lightning impulse voltages with ±140 kVpeak in maximum. It is shown that the growth of positive and negative streamers and the flashover voltage are affected by two interfaces between solid dielectrics, the presence of the back side electrode and the wave tail of applied impulse voltages. The temporal progressing processes of the creeping discharges in PFAE oil are observed using a high-speed image converter camera (ICC). These results on the creeping discharge are compared with those in commercial mineral oil.

Electrorheological and vibration-proof effects in suspension with plate-like aluminum oxide particles

Electrorheological (ER) properties and vibration-proof effect in the suspension dispersed the hexagonal plate-like aluminum oxide particles in silicone oil have been investigated experimentally. On the rheological properties taken with the static and dynamic methods, it is shown that the suspensions are shifted from Newtonian behavior to Bingham behavior by the applied dc electric field. The shear stress depends on the viscosity of dispersion medium (silicone oil) and the particle size. A low current density is an advantage of this ER fluid. The dispersive stability of particles in the test ER fluids has also been examined for the dispersion mediums with different kinematic viscosities. The morphological effect of particles on the ER response is discussed qualitatively. The effect of ER fluid on the vibration control is examined using a single degree-of-freedom (SDOF) system.

Properties of pressure reinforced compact EHD pump

The EHD pump which was composed of the square parallel plate electrodes with a circular hole in the central part was designed to generate the high pressure head. The properties of the generated pressure head PE and corresponding current I were examined as a function of the applied voltage V using hydrofluoroether (HFE7600). The mechanisms of conduction pumping and ion-drag pumping participate in the generated pressure. The maximum pressure head achieved is approximately 35 kPa at 16 kV for twenty pairs of electrodes with 0.5 mm hole and the electric power consumption is 1.15 W.

Electrical and mechanical properties of nanocomposite materials containing electrically dispersed MWCNTs

Pristine carbon nanotubes (CNTs) aggregate severely due to the strong van der Waals binding energies and the dispersibility of CNTs in solvents is extremely poor. This is a formidable hurdle for fabrication of advanced CNT composite materials. The purpose of this research is to realize optimal dispersion of CNTs in organic solvents and to obtain a better understanding of electrical and mechanical properties in polymeric and elastomeric CNT composite materials. In this paper, we report the results obtained by the experiments.

Attempts to measure ion mobilities in EHD liquids by the time-of-flight method

Two different kinds of attempts were made to measure ion mobilities in EHD liquids by using the time-of-flight technique. The first attempt was a reverse polarity method which was similar to that used by L. Yang et al. [5]. The stainless steel coaxial cylindrical electrodes with the effective length of 55 mm and the electrode spacing of 1.5 mm were utilized. The purified two sample liquids; hydrofluoroether (HFE7600) and 2, 3-dihydrodecafluoropentane (HFC43-10) with very low dark current (less than 20 pA at 150 V) were used. In this attempt, it is deduced that the mobility value is of the order of 1×10-8 m2/Vs. In the second attempt, the plate-mesh-plate electrode configuration was employed. One plate was used to apply high voltage pulses and the other plate worked as a counter electrode. The center mesh electrode was kept at low dc voltages. This triode electrode design allows us to monitor the amount of charge injected from the charge injection space to the charge detection space through the mesh electrode during and after the high voltage pulse. Two sample liquids; HFE 7600 and HFC43-10 were used without any purification. Ion drift currents were found to have very long tails. If the tails are included into the drift times, the mobility of ions can be as low as approximately 1×10-9 m2/Vs in both liquids.

Properties of epoxy resin composite containing CNTs dispersed by barrier discharge

The epoxy composites containing the dispersed particles of MWCNTs (fiber or coil type) were produced using a two-fluid mixing type epoxy resin. The dispersion of the original CNTs was carried out by the barrier discharge in 2-ethyl-1-hexanol. The tensile stress of the epoxy composites was reinforced by adding a slight amount (0.02 wt% concentration) of the dispersed CNTs. The maximum stress achieved was 53.4 MPa (46.7 MPa in the breaking stress) for the composite containing the fiber type CNTs. These stress value was approximately 1.3 times of the CNT free epoxy resin.