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This paper proposes a method for detecting the angle of a bearingless motor with less magnetic interference due to the current. Bearingless motors have suspension windings and motor windings that generate leakage flux. Owing to this electromagnetic phenomenon, the signal of the linear Hall‐effect sensor for angle detection is disturbed, and it has to be avoided to place Hall sensors near the winding conventionally. To solve this interference problem, this paper clarifies the ideal combinations between sensor positions and the number of poles and slots of concentrated winding bearingless motors. [ABSTRACT FROM AUTHOR]

A separable connector is used for the power cables and apparatuses in renewable energy systems. The shield of the collector cable is sometimes an open circuit at one end to reduce power loss due to the shield current. However, this has a disadvantage from the viewpoint of lightning protection. The semiconductive part of the separable connector is grounded for safety. The ground potential rise due to a direct lightning strike to a wind tower sometimes damages the collector cables and power apparatuses in the wind tower. Combustion in a cable is one of the most serious types of lightning‐caused damage. This paper describes an experimental study on fire ignition in a collector cable caused by a ground potential rise due to a direct lightning strike to a receptor. The mechanism leading to fire ignition is discussed based on the experimental results. This paper also proposes a countermeasure against such fire ignition. [ABSTRACT FROM AUTHOR]

The axial gap structure of a half‐wave rectified variable field flux motor (AG‐HVFM) has been proposed, which has a double stator structure and field winding short‐circuited by a diode. Although the AG‐HVFM can achieve a high‐efficiency drive in wide speed and torque range via variable field flux control, its structure deteriorates the average torque and torque ripple. In this paper, we sequentially design the core shape, aspect ratio, and current control method for an AG‐HVFM to improve its torque characteristics. [ABSTRACT FROM AUTHOR]

In recent years, wind power generation has been promoted as a countermeasure to global environmental problems. However, the introduction of many wind power generators into the power system may cause system frequency fluctuations. This paper proposes a control method to reduce system frequency fluctuations by using the rotor kinetic energy (RKE) of a variable speed wind turbine (VSWT). When the frequency falls, this method suppresses fluctuations by consuming RKE to increase VSWT power generation, and when it rises, it decreases VSWT power generation by accumulating RKE. The effectiveness of this method is confirmed through simulations using PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

In this paper, a reference stator flux linkage calculation method is proposed for realizing maximum efficiency operation in direct‐torque‐controlled interior permanent magnet synchronous motor (IPMSM) drives. The proposed method is based on the solutions of a quartic equation, a motor model in the d‐q rotating frame widely used for synchronous motor controllers, and a well‐known equation for maximum efficiency operation. Therefore, the proposed method uses neither any approximation function nor any look‐up table that depends on the parameters of the motor, which has to be created in advance. Simulation results validate that the proposed methods can achieve maximum efficiency operation in IPMSM drives. [ABSTRACT FROM AUTHOR]

In this paper, we measured the electrical potential distribution of surface dielectric barrier discharges (SDBD) caused by alternating voltage in synthetic air and nitrogen using the Pockels effect. It was shown that different potential distributions of filament thickness and length are generated in synthetic air and nitrogen. A filament analysis based on mathematical morphology was performed to quantify the geometric characteristics of the filaments produced in each gas atmosphere. The results show that the discharge filament thickness and the entropy in the filament direction depend on the oxygen ratio and the magnitude of the applied voltage. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous motors (PMSM) are very popular in the industrial market. Recently, robots are installed to compensate for the shortage of labor. Due to the increase in motors, the number of power lines and position sensor cable wiring are increased; this increase in complicated wiring is a problem. As a method to solve these problems, power superimposition technology in the power line of a PMSM is expected to reduce the distribution cables. In this paper, the power superposition technology method, and circuit equations of mounting transformers in power lines are presented and are then verified by experiment, simulation, and linear analysis. The circuit equation is proposed as a three‐phase circuit equation, which is transformed into a dq‐circuit equation by a transformation matrix. The characteristics of the electric angular frequency versus the dq‐axis voltage demonstrated satisfactory results, with errors within 1% in linear analysis and simulation. The linear analysis and experiment are shown to be similar, although there are some errors. The validity of the circuit equations could be demonstrated by the verification results. [ABSTRACT FROM AUTHOR]

This paper describes the observed position dependent emission spectrum and vacuum ultraviolet (VUV) to clarify the optical structure of argon atmospheric pressure plasma jets (APJs). Visible emission spectra of argon, nitrogen, and OH molecules were measured as a function of position from the nozzle of plasma jet generator to gas flow direction. From the results, we realized that a certain electric field is required for producing high energy excited atoms of argon in the jet from the high voltage electrode in the device to the ground positioned at downstream side. Moreover, VUV was detected along the plasma jet through the downstream direction. Thus, we could picture that the light pattern of plasma jet of which intensity weaken depend to the distance from the nozzle is sustained by the above two factors with the present steady state experiments. [ABSTRACT FROM AUTHOR]

Since a motor drive system contains an inverter (high‐voltage circuit) and gate drive circuits (low‐voltage circit) with a switching regulator, electromagnetic noise is generated in each of these two circuits, and noise interference between these circuits can occur. This paper discusses noise interference between the high‐ and low‐voltage circuits of an electric compressor system with an integrated mechanical and electrical structure. Analysis using LTspice shows that the experimental and analytical results are in good agreement when a very small stray capacitance occurs between the high‐ and low‐voltage circuits. An experiment using an actual compressor showed that conducted noise above 20 MHz can be reduced by up to 10 dB by reducing the effect of stray capacitance between these circuits. [ABSTRACT FROM AUTHOR]

A model expressing beams, pillars, and electrical wiring in a building for lightning surge simulation by circuit analysis method is proposed in this paper. The proposed model expresses the self‐surge impedance of the electrical wiring as a function of the distance between conductors and the radius of the electrical wiring. The mutual impedance is expressed by the distance between the surfaces of a structure and a nearby wire instead of the distance between the conductor centers. In the case of two conductors having far different radii in proximity, the distribution of electromagnetic fields around the two conductors is similar in horizontal and vertical arrangements. Thus, the electrical wiring nearby pillars can be treated as a horizontal conductor. The circuit analysis results show that the voltage difference generated between the structure and the electrical wiring is calculated more precisely by the proposed model than by the conventional model. [ABSTRACT FROM AUTHOR]