Commutator Segment Research Articles

A Controlled Mechanical–Electronic Hybrid Commutation Theory and Position Sensorless Control

Both brushed dc motors and brushless dc motors have a wide range of applications, but mechanical commutating devices have the problem of harmful commutation arcs, and electronic commutating devices increase the cost of control systems. The uncontrolled mechanical–electronic hybrid commutating device passively controls the voltage of the freewheeling commutator segment through the capacitor, but the capacitor, inductor and resistor with fixed parameters in the freewheeling circuit are difficult to apply to the entire operating range. Therefore, this article proposes a controlled mechanical–electronic hybrid commutating device and a position sensorless control method. The mechanical component realizes the conduction mode of 120 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> square waves through brushes and a mechanical commutator. The electronic component actively controls the voltages of the commutator segments through the power electronic switches in the commutation circuit so that the brush and the newly separated commutator segment remain equipotent, and the gap between them does not bear voltage, which is equivalent to operating in the brush-slip ring state and completely solves the problem of sparking and arcing during the commutation process. The controlled hybrid commutating device requires only two switches to obtain the same commutation effect as the electronic commutating device with six switches and does not require a position sensor or control chip, which reduces the system cost. The validity and feasibility of the controlled mechanical–electronic hybrid commutation theory and device are verified by experiments.

Arc Discharge during Commutation Process in DC Motor Immersed in Ethanol: Approach to Contact State of Brush on Commutator Segment

Arc Discharge during Commutation Process in DC Motor Immersed in Ethanol: Approach to Contact State of Brush on Commutator Segment

Failure assessment using accelerated testing on IC engine’s starter motor for reliability improvement

Generally, starter motors are tested at increased usage rate to verify the durability of the component and to identify the premature failure aspects in the controlled ambient environment. During the process, the latent failures which exhibit unique failure modes at variable environment are hidden, which can impact the warranty of the product. Specifically the Stop–Start (SS)-type starter motors, which often work under increased thermal condition, may show latent failures. Principally, a starter motor is mounted over the IC engine where the working temperature is always between 60 and 120 °C, to establish easy contact with the engine flywheel during cranking. Hence, identifying the latent failures of the starter motor at increased thermal condition is useful to ensure the reliability of the motor as per the requirements of automotive manufacturers. This paper emphasis to improve the reliability of the starter motor’s commutator for high-temperature applications, which may exhibit the failure mode of “Commutator Segment Lift”. The said analysis is performed using time-to-failure data from the laboratory testing of proto samples. This reliability study for the design improvement on commutator includes failure mechanism study, failure source identification and failure improvement.

Design of Resistance Measurement Equipment for Motor Commutator Segment Based on LabWindows/CVI

Traditional resistance measurement for DC motor commutator segment is manual. The process is complicated, the efficiency is low, and the cost is high. In order to enhance efficiency and precision of the resistance measurement, we design an automatic measurement equipment using virtual instrument technique. The equipment consists on industrial compute, stepping motor drive transmission system, low resistance measuring meter, host compute software. Making the equipment universal and automated is the core of design. We discuss working principle of the equipment, hardware de- sign, software design, measurement experiment process and results analysis. Hardware design includes accurate position control of stepping motor, 4-wire method for resistance measurement, special fixture design for probe. Software design based on LabWindows/CVI platform includes serial communication, asynchronous timers, multi-thread, ActiveX control. The measurement experiment results indicate that the euipment can measure almost all kind of DC motor rotors accurate- ly, also can record and save measurement results automatically.

회로정수를 이용한 직류전동기의 정류회로 모델링 및 특성 해석

Because of high torque and easiness of speed control, Direct Current(DC) motors have been used for a long time. But, its applications are limited in circumstance and performance, since they contained brush and commutator. The commutation characteristic gives effect to life and performance of the DC motor. Naturally, the commutation characteristic analysis is strongly required. In this paper, With the result of finite element analysis, The inductance is calculated each rotor position and applied to the voltage equations coupled with commutation equation. Also, contact resistances of brush/commutator assembly are considered using contact area and brush width converted with commutator segments. The time derivative term in the differential equation is solved in time difference method. This algorithm was applied to 2-pole shunt DC motor. We considered commutation characteristic by changing contact resistance between brush and commutator segment.

B119 高速度カメラによる小形モータの整流火花の撮影

We have done some attempts to understand the mechanism of commutation spark generation in universal motor from the image aspect using a high-speed camera. We have also mentioned about the generation of single and plural number of sparks at one commutator segment and the voltage between brush and commutator segment. The commutation sparks of the motor are generated with a sliding contact between brush and commutator segment in the moment that the segment is separated from the brush. And the width of the brush is just 10mm, this time, we were able to clarify position of the brush which sparks are generated and the relation between positive brush and negative brush.

Unraveling the Image of Commutation Spark Generated in Universal Motors

A universal motor, which is mainly used in vacuum cleaners, generates commutation sparks at the moment when the brush and the commutator segment are separated from each other during rotation. This study investigates the mechanism of commutation spark generation by analyzing high-speed camera images and its electrical aspect. We invented a new external trigger method that used laser light as the trigger signal for the shuttering a high-speed camera. This method enabled us to photograph sparks on any desired commutator segments during high-speed rotation, and that made the analysis after photographing easier. This paper shows that commutation sparks in universal motors are generated on every other commutator segment and at the peak of pulses in the voltage between the brush and commutator segment. Other aspects are also clarified, such as the generation of the singular and plural number of sparks on one commutator segment at a time, the time from the moment of spark generation to extinction, and spark generation during a single rotation.

The Distribution of Commutation Sparks in Universal Motors

We have done some attempts to understand the mechanism of commutation spark generation in universal motor from the image aspect using a high-speed camera. We have also mentioned about the generation of single and plural number of sparks at one commutator segment and the voltage between brush and commutator segment. This time, we investigated spark generation distribution and their position of the brush, by photographing all the sparks generated during a single-rotation of the motor. As a result, it’s become clear that there is increasing of spark generation in the position near the side where the armature coil of the brush is connected.

B124 高速度カメラによる整流火花発生位置の検討

Using high-speed camera, we have been doing some experiments to clarify the mechanism of the commutation spark generation from the image aspect in universal motor. Previously we mentioned about the cases of single and plural number of sparks generation at single commutator segment This time, we took pictures of all the sparks generated during a single-rotation of the motor and examined sparks generation distribution and their positions of the brush. As a result, we observed that the closer the position to the side where the brush and the armature coil are connected the more sparks are generated. Also we measured the voltage between brush and commutator segment.

A213高速度カメラによる小形モータの整流火花の可視化

Universal motors are used in mainly cleaners. The commutating processes take place by sliding contact of commutator segment and brush, and sparks occur when a segment separates from the brush. The commutation sparks cause wear on the brush and electromagnetic interference to other electronic machines. We visualized images of sparks on high-revolving. motors by a high-speed camera, and analyzed the mechanism of the spark generation. We devised external laser triggering using laser light for shuttering of the camera. This method make it easier to analyze images because it provides with images of the same point of the same segment every time. By photographing spark generation with a high-speed camera by external laser triggering we probed that sparks occurred on every other segment and also visualized that commutation spark occurred on one segment.

Photographing the Commutation Spark from Universal Motor by External Laser Trigger Method.

We have attempted to clarify the mechanism of generating commutation spark by means of the images photographed with a high-speed camera. In the photographing system with the high-speed camera, we have contrived a new external laser trigger method that uses a laser beam as trigger signal for shutting of camera. In the external laser trigger method, we provide the motor fan with a 1-mm hole. When the laser beam passes through this hole, a trigger signal is generated, and this trigger signal performs shuttering of the high-speed camera via an optical detector and a pulse generator. The new external laser trigger method has enabled us to photograph spark of any commutator segment of the motor in high-speed rotation. Moreover, it has also become possible to photograph the process from generation to extinction of commutation spark, making us capable of analyzing the commutation spark from photographed images.

Photographing of Commutation Spark by External Laser Triggering.

The single-phase AC commutator motor (universal motor) is a compact, lightweight and high-revolution motor that is widely used in such domestic electric appliances as cleaners, juicers, electric drills. Some problems generated by commutation sparks are wear on the brush and noise impediments. We have therefore attempted to use a high-speed camera to elucidate the commutation spark mechanism visually. We proposed an external trigger method that an argon laser is used for the external trigger signal of high-speed camera. This method enabled us to photograph the motor's commutator segment from any position.

Dynamic study of an electronically brushless DC machine via computer simulations

The authors analyze a machine with a conventional DC armature winding on the stator which does not have a field winding connected with slip rings. At positions where the winding would have been attached to a commutator segment, a transistor switch is attached instead. The rotor contains a permanent magnet field. The lap wound stator winding is sequentially commutated by a system consisting of a position sensor and logic circuitry. Analytical expressions for a full pitch lap wound machine are given. A computer simulation of the machine was implemented. The results serve to illustrate the considerations which must be made in the design of this type of machine, in particular the effects of the winding design on commutation and cost efficiency.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>