In recent years, the demand for safer vehicles has increased. Active front steering (AFS) is an effective technique to stabilize motion control after the detection of dangerous motion of a vehicle, such as a slip. However, if AFS intervenes excessively during the steering process, it becomes difficult to prevent interference between driver steering and automatic steering by AFS. Therefore, at present, vehicles are rarely equipped with AFS. This paper proposes a steering torque control method based on reaction torque estimation and variable damping control for use in a human-friendly AFS system and discusses how an experimental device was used to verify the effectiveness of this control method.

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The recent miniaturization and increase in the complexity of electrical devices have increased the influence of impurities on the device performance, especially the influence of small conductive particles with a size on the order of micrometers. Therefore, the inspection of devices during the manufacturing process has become important. In this study, changes in the resonance properties of a microwave cavity were used to detect a metal particle. The decrease in the resonance frequency for a 100µm stainless steel sphere was about 0.1MHz, which was less than 1ppm of the resonance frequency used. This frequency change is too small to detect directly in the output of a particle detector. Transmission measurements (the scattering parameter S21) at a frequency that was few megahertz higher than the resonance frequency where the S21 changes sharply were used to magnify signal changes resulting from the introduction of a small conductive particle. A resonance frequency of 13.3GHz and a frequency 3MHz higher were chosen for obtaining measurements in the present study. By applying a filtering technique, it was shown that the minimum detectable sphere size is around 50µm. This sensitivity was experimentally shown to be uneven along the long axis of the cavity. The unevenness was related to the electrical field strength of the standing wave at the resonance frequency. For practical industrial inspection of devices, multiple frequencies should be employed in view of the present discussion.

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SPMSMs (Surface Permanent Magnet Synchronous Motors) are employed for many industrial applications. SPMSM drive systems should realize a quick torque response and have a wide operating range. For quick current response in field-weakening region, a new current control based on final-state control is proposed in this study. Final-state control settles state variables in a final state from an initial state with feedforward input during finite time. In addition, current response under voltage limit is analyzed by the voltage limit circle of SPMSM with transient term.

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Induction motors are very widely used in various industrial applications. In semiconductor manufacturing processes, deadlock failure of pumps may occur by the adhering of glass material contained in the gas to the rotor. This can lead to the shutdown of the manufacturing plant. Therefore, a countermeasure to prevent deadlocking of a motor is required.
This paper proposes a method for generating an impulse torque in an induction motor fed by an inverter. The proposed inverter circuit is composed of a conventional inverter and a few additional relays. The on-and-off control of the relays supplies an appropriate magnetizing current and a large torque current from the dc-link capacitor.
In experiment, a 1.5-kW cage-type induction motor generated a torque that was approximately seven times larger than the rated torque of the motor. This large impulse torque is useful for breaking the motor deadlock.

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This paper presents a method that allows simultaneous map building and path planning for mobile robots in unknown environments. A graphical representation of a workspace in variable resolutions is constructed using measurement data obtained by omnidirectional distance sensors. At the same time, a search for a feasible path to the target destination is executed using the constructed graph map. The proposed method is evaluated by performing simulations and experiments using an omni directional mobile robot equipped with laser range finders.

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A methodology for realizing a higher-power-density DC-DC converter has been proposed for a power unit installed in a 380-V DC distribution system. The possibility of the converter design will be strengthened by using the series-parallel connection topology for isolated DC-DC converters. A converter prototype with a power density of 10W/cm³ has been fabricated, and the feasibility of the converter design has been confirmed experimentally. This result contributes to the realization of a highly efficient and highly space-saving 380-V DC distribution system.

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For the detection of islanding, it is very important to choose the threshold value of harmonic voltage change. In this paper, we propose an analytical model of the pole transformer using a Fourier series, and will clarify the nonlinear magnetizing characteristics of the pole transformer in islanding area. After determining the proposed model coefficients from the tests of the pole transformer excited by sinusoidal voltage, the distorted wave voltage tests were performed under the condition that the third harmonic voltage or the fifth harmonic voltage was superimposed. The results of the testing showed that the magnetic properties vary greatly upon increasing the harmonic component of the voltage. The analysis and measurement results were in good agreement. By using the proposed method, the distributed generators (DGs) can estimate the magnetizing characteristics of the pole transformer by monitoring the connected terminal voltage. So, as the active signal for islanding detection, DGs can inject the harmonic current synchronized to exciting current harmonics of the pole transformer into the distribution network. In the case of the DGs equipped with the above functions, there is no need to change the settings about the islanding detection threshold of harmonic voltage change, even when there is an excitation voltage change or an increase in the number of DGs.

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A method for designing a sensitivity function by taking into consideration the step response is proposed. The target for the position control is generated by a feedback, instead of a feedforward controller, to improve the step response profile for perturbations in plant gain. The sampling rate for generating the target is slower than the rate for the position control to suppress the mechanical resonances at a high-frequency range. The method is applied to the hard disk drive (HDD) benchmark, and an improved step response is obtained.

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Permanent magnets made of rare earth materials are used in interior permanent magnet synchronous motors (IPMSMs), which are major component of hybrid electric vehicles. The recent remarkable increase in the cost of rare earth materials is a major concern. A switched reluctance motor (SRM) without permanent magnets is one of the possible alternatives. Two types of SRMs have been designed with different materials. The SRMs have been investigated full loading tests. This paper reports a comparison between experimental and analysis results for the SRMs. The efficiency of both SRMs can exceed 90%, and the output power can be in excess of 50kW.

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The fundamental analysis of power supply and rectifiers used for wireless power transfer with magnetic resonant coupling (MRC) is discussed in this paper. The MRC enables an efficient wireless power transfer over middle-range transfer distances. MRC for wireless power transfer is desired to operate at high frequency in the industry science medical (ISM) band, such as 13.56MHz, because the size of the transfer device decreases with increasing transfer frequency. Therefore, the output frequency of the power supply on the transmitting side should be 13.56MHz. In addition, the rectifier on the receiving side is operated with a high efficiency.
This paper focuses on the reflected power on the power supply and rectifiers. Thus, the parametric design method is clarified with power supply including a low-frequency pass filter (LPF) to match the output, impedance of the power supply with the characteristic impedance of the transmission line. In addition, the effects due to the rectifiers with SiC and GaN diodes are confirmed by performing an experiment and a loss analysis.

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Our research focuses on power conversion and its control especially matrix converter, multi-level converter, DC-DC converter. Furthermore AC motor drives, wireless power transfer system, high frequency power circuit and new device technology.

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