Yuichi Yokoi

Stator Design of Alternate Slot Winding for Reducing Torque Pulsation With Magnet Designs in Surface-Mounted Permanent Magnet Motors

This paper proposes a stator design that consists of a combination of an alternate slot winding and dummy slots to minimize pulsating torque in surface-mounted permanent magnet synchronous motors. The alternate arrangement of winding coils is designed to eliminate a harmonic component of back electromotive force that gives rise to a harmonic component of pulsating torque. However, the non-uniform arrangement of slots decreases the frequency of the cogging torque by half and may aggravate torque pulsation. To compensate for the drawback or the decrease in the frequency of the cogging torque, dummy slots are introduced in the alternately slotted stator. A theoretical method is developed for the proposed stator combination. The proposed stator design is applied to a prototype in combination with other rotor magnet design techniques, such as magnet shifting and the adjustment of magnet width, to minimize pulsating torque. The results show that the designed motor reduces the ripple factor of the torque by approximately 30% relative to the original value. In addition, the proposed alternate slot winding is validated by comparing the design with equal slot-winding designs optimized through finite-element method analysis.

On the improvement performance of a dual rotor segment type SRM

A dual rotor segment type switched reluctance motor (SRM) is proposed for flat configuration. It has toroidal stator coil and has inner rotor as well as outer rotor. The performance characteristics are calculated using finite element method. On a flat type SRM, leakage flux is greatly generated at both side coil. To reduce the leakage flux we propose shield structure. Effectiveness of the shield structure is verified analytically.

Experimental characteristics of a novel synchronous generator for wind power generation

A novel synchronous generator has been developed for wind power generation. The generator does not require slip rings and brushes for field power supply as well as permanent magnets. The field flux is generated by the half-wave rectified excitation method. In this paper, the basic principle is explained. Then a test machine is produced and the performance characteristics are shown analytically and experimentally.

Principle and characteristic analysis of a half-wave rectified brushless synchronous generator

In this paper, we proposed “half-wave rectified brushless synchronous generator” using a half-wave rectification excitation system, and we analyze of the basic characteristics by the finite element method.

A study on load characteristics of vibration energy harvester using parametrically excited pendulum

This paper studies the dynamics of the proposed vibration energy harvester to develop the method of designs and controls for the system. The harvester converts vibrational energy into electrical energy through rotational motion of a mechanical pendulum or a so-called parametric pendulum. The rotation is maintained for periodic vibration with appropriate amplitude and frequency. However, such appropriate vibration is not always supplied from nature. For this reason, reasonable energy conversion requires system designs including the electrical circuit for output power and control methods to establish and maintain the rotation against vibrations of nature. The study on the load characteristics of the system indicates the possibility to control the behavior of the mechanical pendulum by regulating the electrical load and to improve the mechanical characteristics by designing the load.

Fractional slot winding design method of Permanent-Magnet Synchronous Machines using Slot Star Diagram

In recent years, Permanent-Magnet-Type Synchronous Machine is used in many applications for industrial drive for the improved performance. Especially, for the armature winding, the fractional slot winding is known about the improved efficiency performance and torque ripple performance. In this paper, we proposed the irregular pitch winding on the fractional slot winding to improve torque ripple characteristics, used the rectangle shape magnet. At the case of the conventional regular pitch winding, we can calculate the winding factor Kw by the typical formula. But at this irregular pitch, it is too difficult to seek Kw from the formula. So, we propose the solution to seek Kw used “Slot Star Diagram” on the irregular pitch, and we seek the optimum the irregular pitch angle to decrease the harmonic component in EMF considered with the field magnet shape. For it, we explain how to derive by using “Slot Star Diagram” for the winding arrangement to be simply. And in the case of the odd and even slot, it has given the examples for each, which describes the procedure of derivation of the winding factor Kw.

Design analysis of a line-start permanent magnet linear synchronous motor

Characteristics of a line-start permanent magnet linear synchronous motor are presented. The motor is a surface permanent magnet synchronous motor with aluminum plate. It starts and accelerates as an induction motor and moves as a synchronous motor. Design analysis is performed. Basic characteristics in analysis using a finite element method are shown.

Design analysis of a segment type linear switched reluctance motor

A segment type linear switched reluctance motor is proposed for a linear actuator or a liner generator. A flat gap motor and a cylindrical gap motor are designed and their characteristics are compared. The movers have concentrated armature windings. The stators consist of segment cores and aluminum block bodies. The characteristics are calculated using a finite element method analysis. The efficiency of the cylindrical gap motor is larger than the flat gap motor because the armature windings without end windings reduces copper loss.

Efficiency improvement of a self-start type permanent magnet synchronous motor

Recently, a permanent magnet type synchronous motor (PMSM) has been widely used. The PMSM cannot start without an inverter. The authors have proposed in a previous paper a novel self-start type PMSM which moves as induction motor at asynchronous speed region and moves as synchronous motor at synchronous speed. It was surface type PMSM and had relatively large area squirrel-cage region. This paper shows design method for improving efficiency analytically.

Motion characteristics of a novel self-start type permanent magnet synchronous motor

Recently, a permanent magnet type synchronous motor has been used widely for industry application. In the paper, we propose a novel self-start type permanent magnet synchronous motor with squirrel-cage. The motor is designed for high torque and high degree of efficiency. The motion characteristics are simulated. It is confirmed that the motor operates satisfactory from start to synchronous speed.