Shinji Wakao

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This paper investigates a starting procedure of rotational sensorless permanent magnet synchronous motor (PMSM) in the rotating condition, which is suitable for some applications with higher maximum rotor frequency and longer current sampling time. Instantaneous estimation of initial rotor position and frequency, right after gates start, is essential for(More)
Analysis and modeling of electric energy demand is indispensable for power planning, operation, facility investment, and urban planning. Because of recent development of renewable energy generation systems oriented for households, there is also a great demand for analysing the electricity usage and optimizing the way to install electricity generation(More)
In this study, we analyze energy consumption of FC-EDLC hybrid railway vehicle to reveal the energy reduction effect. To evaluate this effect properly, we adopt dynamic programming which is optimal control theory. Dynamic programming enables us to calculate energy consumption under optimized control of power sources. In this paper, we evaluate the(More)
This paper investigates a new flux-weakening operation of interior permanent magnet synchronous motors for railway vehicle traction. A design method of the controller is also suggested. The control method is verified both numerically and experimentally to ensure that it is feasible enough to be applied to the railway vehicle traction system
Solar power, wind power, and co-generation (combined heat and power) systems are possible candidate for household power generation. These systems have their advantages and disadvantages. To propose the optimal combination of the power generation systems, the extraction of basic patterns of energy consumption of the house is required. In this study, energy(More)
This paper presents the theoretical studies on the DC-link current harmonics in the inverter-controlled DC electric railcar. First, we derive the mathematical expression of the harmonics. And comparison among a theoretical result, a numerical simulation result, and an experimental result is also presented for verification of the proposed theoretical(More)
Electricity consumption in households varies dependent on a lot of possible reasons such as lifestyle, family configuration, and weather. It is of great importance to optimize the electricity generation system to install for each household. In our previous work, we proposed a clustering approach for extracting a small number of basic electricity consumption(More)
This paper studies a magnetic polarity detection method for permanent magnet reluctance motor (PRM). Inductance characteristic of PRM is different from that of common interior permanent magnet synchronous motor. The inductance characteristic of PRM is verified by electromagnetic field analysis. Moreover, this paper proposes novel magnetic polarity detection(More)
This paper examines the relationship among injected harmonic voltage, acoustic noise, and position estimation error in a position sensorless control method at low speed range using harmonic voltage injection. Moreover, a novel injected voltage control method for reducing the acoustic noise is proposed. The proposed control method is verified by numerical(More)
Recently, remarkable developments of new energy technologies have been achieved against various energy problems. Photovoltaic (PV) system, one of such technologies, has an advantage of utilizing infinite and clean energy. On the contrary, it also has a disadvantage of unreliable power supply mainly caused by unstable weather. The fluctuation of the power(More)