Noriyoshi Nishiyama

Application of fine-grained doubly oriented electrical steel to IPM synchronous motor

Application of fine-grained doubly oriented electrical steel sheets that have a strong {100}<001> texture to synchronous interior permanent magnet motors has been investigated. The alteration in stator core material from high grade nonoriented electrical steel sheets to the doubly oriented material with a simple change in stator design was found to lead to an increase in efficiency up to more than 2%. This efficiency increase is ascribed to a larger permeability and a lower iron loss in two perpendicular directions of the doubly oriented material. Finite-element analysis has revealed that the magnetic field distribution in stator cores made of the doubly oriented material is largely different from that in stator cores made of the nonoriented material.

High performance design of an interior permanent magnet synchronous reluctance motor for electric vehicles

We have examined the optimum rotor design of an interior permanent magnet motor (IPM motor) for electric vehicles. By using double-layer magnets embedded into the rotor with the layers separated in the direction of the rotor radius, we have been able to construct a rotor that takes greatest advantage of reluctance torque, resulting in a 10 percent torque increase over the conventional IPM motor, which uses only a single-layer of magnets in the rotor.

Recent technical trends in variable flux motors

This paper reviews recent technical trends in variable flux motors. Permanent magnet motor is a major component to realize high torque density with keeping high efficiency. However, when high speed revolution is required for further miniaturization, as well as the large torque in the low speed region, the flux yielded by the permanent magnet encounters a serious trade-off, i.e. the former needs less flux and the latter requires much. The solution for this trade-off is varying the flux. In general, the flux of the permanent magnet is constant, and many efforts are under development to overcome this as to be shown in this paper.

The Study of Demagnetization of the Magnetic Orientation of Permanent Magnets for IPMSM with Field-Weakening Control under Hot Temperature

In this study, we investigate the demagnetization resistance of a concentrated winding IPMSM (interior permanent magnet synchronous motor) accounting for field weakening control by changing the magnetization direction of the permanent magnet under a high-temperature environment. IPMSMs are investigated by FEA (finite element analysis) using the same volume of the permanent magnet while changing the magnet’s width, thickness and magnetic field orientation angle. FEA found that a V-shaped angle Va = 100° and a changed magnet length of 97% using an oblique magnetic-field-oriented magnet strike a good balance between demagnetization resistance and torque at 180 °C. Comparison between demagnetization of negative d-axis current (current phase β = 90°) and demagnetization of field weakening control (β = 80°) using concentrated winding IPMSM with V-shaped angle Va = 100° is conducted. With the demagnetization factor at β = 80° for β = 90°, the demagnetization factor 0.39 (2.6 times) at α = 0° decreases to 0.23 (4.3 times) at α = 20°. The demagnetization resistance in the field weakening control is further improved.

The study of highly demagnetization performance IPMSM under hot environments

This, paper examines how changing the magnetic orientation of permanent magnets in concentrated winding interior permanent magnet synchronous motors (IPMSMs) affects their demagnetization resistance. We evaluated a prototype for demagnetization at 180°C that consists of a 130-degree V-shaped rotor core in which parallelogram magnets with oblique orientation are arranged and confirmed by finite element analysis (FEA) where the demagnetization resistance increases as magnetic field orientation angle α becomes larger. We confirmed the coercivity influence at the end of the magnet by evaluating our prototype.

Development of High-efficient Compact Organic Rankine Cycle Power Generation Technology utilizing Waste Heat

As the effective utilization method of unused heat energy between 100 and 300 degree-C in the industrial sector, Organic Rankine Cycle (ORC) was selected from the viewpoint of high efficiency. The prototype of air-cooled compact ORC electric power generation system for 1kW class was evaluated in variation of the ambient temperature of condenser and the suction temperature of expander. In the experimental results, at the expander suction temperature of 175 °C and the ambient temperature of 20 °C for condenser, the generated power by the expander is 1,027W and the gross power generation efficiency is 10.3%. The net power generation efficiency, considering the input power of auxiliary equipment such as pumps and fans, is 9.0%. In the result of energy balance analysis, power consumptions of the pump and the fan are small and almost of the generated power is effectively available.

Application of fine-grained doubly oriented electrical IPM synchronous motor

The magnetic core materials for motors have been mostly limited to non-oriented electrical steels of which crystallographic texture is almost random, although there is a possibility to greatly improve performance of motors by the use of steels with textures such as {100}<001>.The purpose of this research is to investigate how the performance of motors can be improved by the use of such a textured material by building actual motors using a doubly oriented electrical steel that has a strong {100}<001> texture. This key material in this investigation has been prepared by the process so-called oxide-separator-induced decarburization that has been found recently.