Yuta Niwa

Propositions for the analysis of commutation phenomenon and the modeling of universal motors based on introducing the state function method into FEM electromagnetic field analysis

The universal motors of our advanced research use FEM simulations to perform modeling of universal motors rotating at ultrahigh speed by using the like state function method with respect to the details regarding the commutation scintillation phenomenon of the commutators, the air gap surface, and the contact condition of the brushes. As a result, at the design stage, the commutation scintillation phenomenon was quantitatively estimated and an investigation was performed with respect to the configuration of the iron core. Furthermore, an example of this modeling method based on FEM analysis was performed with regard to the electromotive force of the transformer, the armature reaction and the scintillation voltage including the contact resistance of the brushes resulting from the rotation, the configuration of the iron core, and the changes in the gap permeance. Regarding the validity of this analysis, an extremely close match was attained between the results of the present simulation and the experimental results. In this regard, the target model motor was a 1.5 kW, 33,000rpm ultrahighspeed, high-capacity universal motor for cleaners.

Harmonic restraint technique of stator core shape and non uniform air-gaped universal motors for vacuum cleaner

This paper focuses on the restraint method of the 3rd harmonics current, in which close attention has been paid to the iron core shape of the universal motor for power vacuum cleaners. In this paper, the gap permeance, magnetic saturation of an iron core, and the influence that a slot ripple has on harmonic current were verified using FEM electromagnetism analysis. As the result, stator core shape proved quantitatively that a restraint of harmonic current has an effect. The authors think assert that a design manual should be adapted to create an international standard about a restraint of the harmonic current of a universal motor.

Third harmonic restraint technique for the cleaner universal motor under power controller

This paper explores the simulation technique of the harmonic current under phase angle control of a universal motor. The harmonic current generates the damage-by-fire accident of the transformer and phase advance capacitor, both of which are connected to an electric power system. This problem has warranted new standards imposed by the IEC. Comparatively, the universal motor for vacuum cleaners is powered by phase angle control by TRIAC. The key differentiator among these products is cost, a key issue in the current discussions with the IEC. Our team sought to analyze the performance of the harmonic current of the universal motor under strict analysis conditions. The result coincided with the actual measurement of the instantaneous value of the harmonic current at the time of the phase angle control. Therefore, our team concluded it is possible for developers to consider harmonics restraint and differentiation.

The relation of a brush life to the commutator width and brush width ratio of a universal motor

This paper considers examination of a brush life as the commutation phenomenon over the commutator width and brush width ratio of a universal motor. It can imagine that how a commutator width and brush width ratio has big influence on operation efficiency and a brush life. However, the authors are not yet looking at the report which the optimal value of the commutator width and brush width ratio considered. In this paper, a commutation phenomenon is grasped using the coupling analysis simulation by using FLUX ○R software and it detail commutation phenomenon measuring device which we propose newly. Furthermore, it was examined whether it would have influence on the life of brushes and commutators. From this result, the optimal point of the commutator width and brush width ratio, to a brush life was predicted.

The torque free phenomena and it's application of disc-type ultrasonic motors

Two kinds of ultrasonic motors are known. One is a ring type with a small torque for autofocusing a camera. Another is a disk type for use as a power actuator. In this paper, a simulation by ATILA Soft ware was performed to elucidation the torque-free phenomenon of the disc rotor type for the latter power actuators, and the abnormal noise-generating phenomenon was successfully enduced.

Multi induction motor connected network residual voltage and it's back power

Due to the current, widespread need for high-speed, high-capacity induction motors, the residual voltage resulting from interrupted power supply conditions must be critically evaluated. Both the electromagnetic shock at its coil end (due to the excessive surge current when the power line is switched over) and the mechanical system impact (due to the greater transient torque) must be specifically investigated. In this paper, the bus residual voltage problem is set as the study target, focusing on induction motors which are connected to a common bus. The analytical method used in this problem and the rapid decay of the residual voltage are clearly demonstrated below, along with comparative investigation and test results. It was proved that the residual voltage and back power of the electric power network (containing many rotating electrical machinery in this case (IM, SM), the capacitor for a back power improvement, etc.) are also subject to quantitative analysis. Although it was thought that these residual voltage and back power conditions were disadvantageous in a system change over, we now understand they are a momentary interruption phenomena of IT power supply equipment. Through a huge mechanical shock, they damage the coil end or shaft torque. Still, these phenomena make the need for high-speed, high-capacity induction motors even more clear.