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In this study, the ringing phenomenon of gallium nitride‐field effect transistor (GaN‐FET) and silicon‐insulated gate bipolar transistor (Si‐IGBT) inverter excitations in a ring sample was thoroughly measured and analyzed by using a high‐quality oscilloscope with a very high sampling rate of 5 giga‐samples per second (GS/s). Owing to the rapid switching of the GaN‐FET power devices in several nanoseconds and the ringing frequencies in the MHz range, the use of the high sampling rate of 5 GS/s is necessary and useful for accurate measurement. The experimental findings and analysis reveal the following three key points: (i) there are two possible types of high‐frequency resonance phenomena, that is, the first one caused by semiconductor devices and circuits and the other generated by the resonance with loads in use. (ii) The ringing phenomenon because of the resonance under the load is considered to be due to the rising time of pulses that are caused by the rapid switching of the semiconductor devices. (iii) The ability to measure and the two types of ringing phenomena depends on the intensity of the white noise of the measuring instrument [ABSTRACT FROM AUTHOR]

This study is the first research to present a detailed assessment of core loss, copper loss and magnetic flux density of the interior permanent magnet synchronous motor (IPMSM) with pulse‐amplitude modulation (PAM) inverter under different excitation angles in both no‐load and load conditions. The PAM method automatically controls the amplitude of changeable DC‐link voltage, and the excitation angle for switches in the inverter is varied from 120° to 180° according to a 12‐step switching pattern designed particularly for the PAM‐based inverter of IPMSM. For reference purpose, the pulse‐width modulation excitation with a very high voltage modulation index is performed. Various conditions with changes in speed and torque are examined. Experimental results show that harmonic components produced by the PAM inverter in the IPMSM current, voltage and magnetic flux density have large effects on the motor core and copper losses; physics‐based explanations and insights are also presented. The PAM under 135° excitation angle has an excellent performance in reducing IPMSM core and copper losses since it can significantly decrease the harmonic components in motor current, voltage and magnetic flux density. Furthermore, simulations using the finite element method are conducted to validate the experimental results of IPMSM core loss with the PAM excitations. [ABSTRACT FROM AUTHOR]

SUMMARY In this study, it is demonstrated that the iron loss from the SiC-MOSFET, which represents a new power semiconductor with an extremely low on-voltage for electric machine drives, is almost the same as that from an Si-IGBT, which is a conventional power semiconductor. In order to evaluate the iron loss characteristics when an SiC device is used, two single-phase pulse width modulation inverters were built and used for the excitation of a ring made up of electrical steel sheet. One of the inverter employed an SiC-MOSFET, and the other inverter employed an Si-IGBT. The iron losses for the two inverters are compared. [ABSTRACT FROM AUTHOR]

A linear induction motor to be able to achieve induction heating and tension in thin steel sheet treatment process is researched. The major problems in the application of the linear induction motor are meandering of thin steel sheet by the electromagnetic force in the normal direction, the heating characteristic, and the evaluation of the thrust force as a tension. As a result of the investigation of the frequency characteristic by means of electromagnetic FEM calculation, it is confirmed that the electromagnetic force in the normal direction which consists of repelling force caused by the magnetization and repulsive force caused by Lorentz force becomes almost zero at the crossover frequency. In this frequency, the temperature of the steel sheet at the front and back have almost the same distribution. Since the tension value converted from the thrust force is about 10% of experiment equipment, the linear induction motor is also useful for the auxiliary function of the tension roll. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(2): 38–47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20845 [ABSTRACT FROM AUTHOR]