A new fault sign detection method for rotators based on one-class support vector machine is proposed. The vibration of rotators occurs not only during faulty operation, but also during normal operation. Furthermore, faults are rare events, and it is difficult to obtain an indication of fault occurrence beforehand. To overcome this issue, a one-class support vector machine with successive multi-level class construction is proposed. The advantage of this method is that the time varied feature can be classified according to the class-set. The experiments are conducted by using actual rotator data. The results show that the class-set feature is capable of indicating the fault sign.
The wear characteristics of copper alloy infiltrated C/C composite contact strips were investigated to identify their dominating wear mechanisms. In this study, we conducted a series of wear experiments, field tests, and measurements of the physical properties of the C/C composite contact strips. The results of the wear experiments indicated that the wear of C/C composite contact strips was proportional to the electric charge of the arc. The C/C composite contact strips with high strength carbon fiber were more likely to wear under high arc discharge energy conditions. From the results of the wear experiments and field tests, it was found that the wear of the C/C composite contact strip increased significantly when the infiltrated copper alloy was melted and ejected from the inside of the contact strip. The main wear mechanisms of the C/C composite contact strips were found to be oxidative wear and adhesive wear.
The Hokuriku Shinkansen line is driven by an AC traction system. Its characteristic feature is that the line consists 50Hz and 60Hz power frequency sections. In the linking section, where two different frequencies of the AC feeding system meet, the induced current causes electromagnetic interference with the ATP system.
Therefore, the traction circuit and the composition of the track circuits were arranged so as to be immune to this interference, and the predictive calculation of the induced current was made. In the calculation, we considered the presence of iron in the infrastructural components such as viaducts, tunnels, and slabs. The calculation results show an influence on the interference caused by the infrastructure.
To validate the actual interference, we measured the interference at the linking sections with two methods. One was the precise static measurement of the feeding circuit and induced current caused by a replica train, which consisted of an oscillator and a power amplifier. The other method used was the dynamic measurement of induced current caused by the actual trains. It was concluded that the interference was allowable, and the interferences on the track circuits and the ATP receiving coil were predicted more precisely than before.
This paper discusses the experimental verification of a virtual synchronous-motor drive test system. This test system consists of two identical modular multilevel double-star chopper-cell (DSCC) converters characterized by a front-to-front (FTF) connection. One converter acts as an inverter under test, while the other acts as a part of the virtual motor and load. The experimental waveforms obtained from the test system designed and constructed in this paper confirm satisfactory electrical and mechanical dynamics of the virtual three-phase 200-V, 10-kW, two-pole, 18,000-r/min synchronous motor with a virtual quadratic-torque-to-speed load an as a high-speed compressor. The driving performance of the test system shows that the DSCC inverter under test is applicable to high-speed synchronous motor drives.
Electric vehicles (EVs) have been intensively studied in the last decade due to their environment-friendly characteristics. However, the miles-per-charge of EVs is less than that of internal combustion engine vehicles. To improve the miles-per-charge, the authors' group proposed a Range Extension Autonomous Driving (READ) system that minimizes consumption energy by optimizing the velocity profile. However, conventional systems can be applied to driving on only straight roads. Therefore, this study extends READ system to be applied to driving not only on straight roads but also on curved roads by modeling the vehicle rotation motion and the cornering resistance. The effectiveness of the proposed method is verified by simulations and experiments.
An isolated AC-DC converter has been used in various applications, such as power supply and as a battery charger for electric vehicle. In conventional converters, a loss in each conversion stage can be reduced by applying a soft switching method.
However, a conventional converter has many conversion stages including the rectifier stage, power factor correction, DC/DC converter stages; thus, it is difficult to reduce the total converter loss and size.
In this paper, we propose a novel isolated-type AC-DC converter with only one conversion stage; it can realize a zero voltage switching operation in all switching devices.
Since piezoelectric elements convert mechanical vibration into electrical power, vibration generators based on piezoelectric elements have been highlighted as low-power sources. This paper investigates the output power improvement of vibration generators based on piezoelectric elements using a passive device, such as an inductor. The proposed circuit is focused on the LC resonance between the added inductor and the internal capacitor. The validity of the proposed circuit is verified both numerically and experimentally.
Recently, there has been an increasing interest in energy saving operations in railway systems due to its significant advantages compared with strategies that involve the enhancement of hardware instruments. The authors focus on Automatic Train Operation (ATO) as a suitable method to evaluate the effects of energy-saving operation under simple conditions. The difference from other previous works is that the authors aim to conduct substantiative experiments on track and design explicitly-considered energy-saving operations. The authors perform on-track tests to measure the efficiency of the motors on trains and the measured values are used for numerical calculation to enhance accuracy. In this study, an energy-saving ATO is designed and installed in rolling stocks. This designed ATO consists of the three following methods: The first method is to install coasting in speed profiles and decrease the maximum speed by jerk regulation. The second method is to use power-limiting braking in the braking section and increase the regenerative energy. The third method is to update the notch control algorithm for using the motor effectively. The authors perform on-track tests to evaluate the energy-saving effect of the proposed method compared with conventional running profiles.
This paper describes an introduction and research activities of Kuzumoto and Horiguchi laboratory of Tokyo Institute of Technology (Tokyo Tech). This laboratory is a joint collaboration of Tokyo Tech and Mitsubishi Electric Corporation. The author is aiming to promote research activities and development of human resources through this industry-academia collaboration.