Small Motors Research Articles

Advance Protection for Three Phase Induction Motor using Microcontroller Atmega32

A low cost and reliable protection scheme has been designed for a three phase induction motor against unbalance voltages, under voltage, over voltage, short circuit and overheating protection. Taking the cost factor into consideration the design has been proposed using microcontroller Atmega32, MOSFETs, relays, small CTs and PTs. However the sensitivity of the protection scheme has been not compromised. The design has been tested online in the laboratory for small motors and the same can be implemented for larger motors by replacing the i-v converters and relays of suitable ratings.

Analysis for electromagnetic performance of PM motor with different metal nano-material bars

With the appearance of high-performance permanent magnet (PM) materials as well as the development of computer technology and nanotechnology and electricity machine theory, scholars have done a lot of research on the self-starting permanent magnet synchronous motor and have made many achievements. Although the starting permanent magnet synchronous motor has many advantages compared with the induction motor, there are also many problems. Since the self-starting motor needs to realise the self-starting and maintaining the synchronous speed operation, its rotor structure design is more complex. The rotor requires the starting winding and the magnets coexist, so there is 'space competition', especially the small motors with high power density. Nowadays, nano-materials are applied on a motor to improve its electromagnetic performance. In this paper, the electromagnetic performance of a PM motor with different metal nano-material bars is researched by finite element analysis (FEA). In this paper, the electromagnetic performance of a PM motor is researched when the rotor bars are with different sizes metal nano-palladium by FEA. The magnetic field distribution, the dynamic speed and torque variation and the eddy current losses are analysed respectively.

Magnetic topology with axial flux concentration: a technique to improve permanent-magnet motor performance

This article presents a different topology for the magnetic circuit of permanent-magnet motors, using the concept of Axial Flux Concentration. By means of longitudinal extension of the rotor length beyond the stator core, a substantial increase in the flux per pole is enabled, improving the general performance of the machine. Even in low cost motors with ferrite magnets, this improvement is easily achieved utilizing the proposed scheme. With rare-earth magnets this technique permits a higher torque density, contributing to the compactness of the machine. This configuration is suitable for several magnetic topologies, but particularly for small diameter and low pole number permanent-magnet motors of the embedded-magnet type. The proposed topology is briefly described and the theoretical aspects presented. It is shown that, from the stator point of view, this scheme behaves like a conventional motor with fictitious equivalent magnets with augmented remanent flux density and recoil permeability. A 3D finite element modeling is performed to validate the theoretical analysis permitting some additional conclusions concerning magnetic saturation. The methodology is applied to a prototype brushless motor constructed for research purposes, composed of a stator and two rotors. Various characteristics are compared, concerning flux per pole, torque, power density and efficiency. The improvement in the performance of the axial flux concentration rotor is confirmed by experimental results, in accordance with the theoretical previsions.

Effect of saturation on response of a single pile embedded in saturated sandy soil to vertical vibration

The dynamic response of a single pile embedded in dry and saturated sandy soil excited by two opposite rotary machines was considered experimentally. A small-scale physical model was manufactured. It consists of: two small motors supplied with eccentric mass (.012 kg) and eccentric distance (20 mm) representing two opposite rotary machines, aluminium shaft with 20 mm in diameter as pile, and a steel plate with dimensions of (160 × 160 × 20 mm) as a pile cap. The experimental work was achieved taking the following parameters into considerations: pile embedment depth ratio (L/d) and operating frequency of the rotary machines. Twenty-four tests were conducted in medium dense sandy soil with 60% relative density. Half of these tests were performed in dry soil and the other was conducted in saturated soil. In all these tests, the strain along pile’s length and the amplitude of vertical vibration for the pile cap were measured. It was found that the axial strain along the pile becomes frequency-dependent, which means that it increases with increasing the operating frequency, as well as its oscillation increases too. The amplitude of vibration at pile head also be frequency-dependent, it increases with increasing the operating frequency.

A Three Revolute-Revolute-Spherical Wearable Fingertip Cutaneous Device for Stiffness Rendering.

We present a novel three Revolute-Revolute-Spherical (3RRS) wearable fingertip device for the rendering of stiffness information. It is composed of a static upper body and a mobile end-effector. The upper body is located on the nail side of the finger, supporting three small servo motors, and the mobile end-effector is in contact with the finger pulp. The two parts are connected by three articulated legs, actuated by the motors. The end-effector can move toward the user's fingertip and rotate it to simulate contacts with arbitrarily-oriented surfaces. Moreover, a vibrotactile motor placed below the end-effector conveys vibrations to the fingertip. The proposed device weights 25g for 35 x 50 x 48 mm dimensions. To test the effectiveness of our wearable haptic device and its level of wearability, we carried out two experiments, enrolling 30 human subjects in total. The first experiment tested the capability of our device in differentiating stiffness information, while the second one focused on evaluating its applicability in an immersive virtual reality scenario. Results showed the effectiveness of the proposed wearable solution, with a JND for stiffness of 208.5 17.2N/m. Moreover, all subjects preferred the virtual interaction experience when provided with wearable cutaneous feedback, even if results also showed that subjects found our device still a bit difficult to use.

Control of the Acrobot with Motors of Atypical Size Using Artificial Intelligence Techniques

An acrobot is a planar robot with a passive actuator in its first joint. The main purpose of this system is to make it rise from the rest position to the inverted pendulum position. This control problem can be divided in the swing-up issue, when the robot has to rise itself by swinging up as a human acrobat does, and the balancing issue, when the robot has to maintain itself in the inverted pendulum position. We have developed three controllers for the swing-up problem applied to two types of motors: small and large. For small motors, we used the State-Action-Reward-State-Action (SARSA) controller and the proportional–derivative (PD) controller with a trajectory generator. For large motors, we propose a new controller to control the acrobot—a pulse-width modulation (PWM) controller. All controllers except SARSA are tuned using a genetic algorithm.

Quantum percolation phase transition and magnetoelectric dipole glass in hexagonal ferrites

Hexagonal ferrites do not only have enormous commercial impact ({\pounds}2 billion/year in sales) due to applications that include ultra-high density memories, credit card stripes, magnetic bar codes, small motors and low-loss microwave devices, they also have fascinating magnetic and ferroelectric quantum properties at low temperatures. Here we report the results of tuning the magnetic ordering temperature in PbFe$_{12-x}$Ga$_x$O$_{19}$ to zero by chemical substitution $x$. The phase transition boundary is found to vary as $T_N \sim (1-x/x_c)^{2/3}$ with $x_c$ very close to the calculated spin percolation threshold which we determine by Monte Carlo simulations, indicating that the zero-temperature phase transition is geometrically driven. We find that this produces a form of compositionally-tuned, insulating, ferrimagnetic quantum criticality. Close to the zero temperature phase transition we observe the emergence of an electric-dipole glass induced by magneto-electric coupling. The strong frequency behaviour of the glass freezing temperature $T_m$ has a Vogel-Fulcher dependence with $T_m$ finite, or suppressed below zero in the zero frequency limit, depending on composition $x$. These quantum-mechanical properties, along with the multiplicity of low-lying modes near to the zero-temperature phase transition, are likely to greatly extend applications of hexaferrites into the realm of quantum and cryogenic technologies.

Nonlinear State Estimation for Trajectory Tracking of a Flexible Parallel Manipulator

Lightweight robots can be advantageous when considering the lower energy consumption, the possibility to use smaller motors and the lower material cost. Nevertheless, in such lightweight structures non-negligible flexibilities are inherent which can lead to significant oscillations making the control more difficult. Within this research end-effector trajectory tracking of a parallel manipulator with a highly flexible link is considered. As centerpiece, a new approach to estimate the state of the system of differential algebraic equations is discussed to obtain the end-effector position and velocity. For the estimator, the kinematic loop is treated by a projection tangential to the constraint manifold which is based on a QR decomposition. Subsequently, an Unscented Kalman Filter is applied and the dependent coordinates are obtained by satisfying the algebraic constraint equations with the Newton-Raphson method. The utilized signals for the estimator are on the one hand position measurements of the actuators which are realized as direct drives and on the other hand measurements of strain gauges attached to the long and highly flexible link. As application, a basic end-effector output controller based on an equivalent rigid model and the transfer function of the dominant first bending eigenmode is utilized to enhance the tracking results. The concepts are applied to an experimental rig for validation purposes and to show first results for end-effector estimation with feedback control.

Position Sensorless Field Oriented Control of IPMSM Under Parameter Uncertainties

Permanent magnet synchronous motors (PMSMs) are widely used in industry due to their high torque per volume ratio, low noise, efficiency and wide stable operation region. Especially in home appliance applications, obtaining high torque using small motors and low audible noise has crucial importance. Therefore, conventional DC motors have been replaced by the permanent magnet synchronous motors in the modern applications. In this study, field oriented sensorless control over wide speed range is carried out under parametric uncertainties. The pole coloring concept is used for the control of a PMSM in an industrial setup for the first time. The design method and experimental results are presented.

Efficiency optimization in small induction motors using magnetic slot wedges

In the last few years, new efficiency requirements for induction motors have been imposed. Therefore electrical machines manufacturers have had to redefine the design criteria in order to reduce losses aiming to achieve the efficiency values established by the IE2 and IE3 standard categories according to the IEC. Given that, in the near future, an increasing demand regarding efficiency (IE4 and IE5 categories) is expected, it would be appropriate to seek new alternatives to further reduce losses in induction motors.In this work, the possibility to use magnetic wedges in induction motors with semi-closed slots is studied. This strategy allows to reduce copper and core losses, therefore increasing then the motor efficiency. The study analyses low power motors and considers different permeabilities and geometries for the magnetic wedges. In addition, it focuses attention on the starting torque and currents.Finally, an experimental validation using a 3-kW 380-V 4-pole IE2-class induction motor is presented.

Vertical vibration capacity of a single pile in dry sand

ABSTRACTIn this study, the dynamic response of pile foundation in dry sandy soil excited by two opposite rotary machines was considered experimentally. A small scale physical model was manufactured to accomplish the experimental work in the laboratory. The physical model consists of two small motors supplied with eccentric mass (0.012 kg) and eccentric distance (20 mm) representing the two opposite rotary machines, an aluminum shaft as the pile, and a steel plate a pile cap. The experimental work was achieved taking the following parameters into considerations: pile embedment depth ratio (L/d, where L is the pile length and d is its diameter) and operating frequency of the rotary machines. All tests were conducted in medium dense fine sandy soil with 60% relative density. Twelve tests were performed to measure the change in load transferred through the pile’s tip to the underlying soil. To predict precisely the dynamic load that will be induced from the rotary machines, a mini load cell with a capacity of 100 kg was mounted between the aluminum plate (the machine base) and the steel plate (pile cap). The results revealed that, before machine operation, the pile tip load was approximately equal to the static load (machine and pile cap), whereas during machines’ operation, the pile tip load decreased for all embedment depth ratios and operating frequencies. This reduction was due to the action of skin friction that was mobilized along the pile during operation, and as a result the factor of safety against pile bearing failure increases. For all operating frequencies and pile lengths, the factor of safety against bearing failure increased during machines’ operation, where the pile tip load became less than its value before starting operation. During operation, the skin friction resistance mobilized along pile length led to decrease the bearing load.

The Influence of Electrical Sheet on the Core Losses at No-Load and Full-Load of Small Power Induction Motors

This paper presents the core losses and performance characteristics of a small power induction motor with the core made from different electrical sheets, supplied from mains or PWM frequency inverter at 50, 100, and 200 Hz. Field-circuit and analytical methods are used for loss calculations, taking into account the nonlinear phenomena and additional core losses. In the calculations, the characteristics of mechanical losses measured against the speed for the motors and different electrical sheets magnetization, for frequencies up to 2000 Hz, as well as losses density characteristics against the flux density were used. The results show a significant increase in core losses concomitant with the motor load increase. In addition, analytical methods were used to calculate the performance characteristics versus load power. Calculated results were verified by measurements.

Weed detecting robot in sugarcane fields using fuzzy real time classifier

The objective of this research work is to propose a weed detecting robotic model for sugarcane fields that uses a fuzzy real time classifier on leaf textures. The differentiation between weed and crop and weed removal are the two challenging tasks for the farmers especially in the Indian sugarcane cultivation scenario. The automatic weed detection and removal becomes a vital task for improving the cost effectiveness and efficiency of the agricultural processes. The detection of weeds by the robotic model employs a Raspberry Pi based control system placed in a moving vehicle. An automated image classification system has been designed which extracts leaf textures and employs a fuzzy real-time classification technique. Morphological operators are applied to extract circular leaf patterns in different scales from the leaf images. An optimal set of features have been identified for the characterization of crops and weeds in sugarcane fields. A weed detecting robotic prototype is designed and developed using a Raspberry Pi micro controller and suitable input output subsystems such as cameras, small light sources and motors with power systems. The prototype’s control incorporates the weed detection mechanism using a Raspbian operating system support and python programming. The designed robotic prototype correctly identifies the sugarcane crop among nine different weed species. The system detects weeds with 92.9% accuracy over a processing time of 0.02s.

Experimental equipment for measuring of rotary air motors parameters

In the article the construction of an experimental device for measuring the parameters of small rotary air motors is described. Further a measurement methodology and measured data processing are described. At the end of the article characteristics of the chosen air motor are presented.

Characteristics of Nd-Fe-B Permanent Magnets Present in Electronic Components

The increasing use of rare earths elements (REEs) in a number of recent technological innovations led to a rapid increase (>50% in the last decade) in their applications. Europe is one of the most important regions of consumption of these substances. In this context, Europe in its 'Raw materials' strategy puts the recycling at the center of its concerns to provide a part of securing its supplies in REEs. Recycling of these substances, on an industrial scale, remains somewhat developed while it presents numerous advantages over the exploitation of primary resources. This paper will present some results obtained from characterization study of permanent magnets (PMs) present in WEEEs. Three components containing PMs are identified: hard disk drives, small electric motors and speakers. The representative sample of these components has been dismantled manually to recover the PMs contained and to quantify their amount. The results show that the weight percentage of the PMs varies from 4 to 6% in the speakers, 2.5 to 2.8% in the hard disks, and between 0.8 and 2% in some electric motors. The results of the thermal treatment of the Nd-Fe-B PMs of the investigated samples show that the majority of these PMs lose their magnetic property upon reaching Curie temperature (300-400°C) in 15-20 min. Scanning Electronic Microscopy reveals the morphological aspects of the PM which consist in crystals shaped tetrahedral phase Nd2Fe14B sintered in the presence of the interphase rich in Nd, Dy and Pr. The PM are layer coated with 20 μm thick, consisting of Ni, Zn or metals alloys.

Transportation and release of Janus micromotors by two-stage rocket hydrogel

A fast two-stage hydrogel rocket is described that displays efficient autonomous motion, long transportation time and the release of Janus micromotors that can self-propel after hydrogel disintegration. Such an attractive two-stage hydrogel rocket holds considerable potential for the on demand delivery of artificial small motors and further diverse applications of nano/micro machines.

Use of Nontraditional Temperatures on Aluminum Caged Centrifuged Rotors Annealing—Assessment of the Viability and Effectiveness in Reducing Interbar Losses

Due to differences in the manufacturing process, centrifuged rotors have higher efficiency and interbar resistance than those produced by the high-pressure die-casting process. Therefore, the annealing applied to high-pressure die casted rotors to improve the insulation of the cage is not traditionally applied by manufacturers to centrifuged rotors. This study evaluates the effect of the traditional 450 °C heat treatment on centrifuged rotors, as well as the feasibility and effects of 520 oC rotor annealing, temperature not recommended for high-pressure die-casted rotors. The efficiency measurements were performed with a dynamometer, using small single-phase motors, usually applied in domestic refrigeration compressors, with a standard stator kept under controlled conditions. A structured test was performed to assess the effects in a mass production scenario, aiming to reflect the variation of the production parameters within the manufacturer specifications.

Development of Excess Pore Water Pressure around Piles Excited by Pure Vertical Vibration

In this study, an assessment to excess pore water pressure generated around a single pile and pile group excited by two opposite rotary machines embedded in saturated sandy soil was considered experimentally. A small-scale physical model was manufactured to accomplish the experimental work in the laboratory. The physical model consists of: two small motors supplied with eccentric mass of 0.012 kg and eccentric distance (20 mm) representing the two opposite rotary machines, an aluminum shaft 20 mm in diameter as the pile, and a steel plate with dimensions of (160 × 160 × 20 mm) as a pile cap. The experimental work was achieved taking the following parameters into considerations: pile embedment depth ratio (L/d), spacing between piles (S) and operating frequency of the rotary machines. Twelve tests were conducted in medium dense fine sandy soil with 60 % relative density. In all these tests, the change in excess pore water pressure was measured around the pile at two spots: at the middle of the pile and at its tip. The results revealed that the generation of excess pore water pressure was affected by the following parameters: slenderness ratio of the pile, operating frequency of the machines, and the soil permeability. However, for all cases, it was found that the pore water pressure generated during operation was not greater than 20 % of the initial hydrostatic pressure. Using pile foundation reduced the amplitude of vertical vibration by about (300 %) for all operating frequencies, lengths of piles, pile spacings and number of piles. In addition, the presence of piles reduced the disturbance (fluctuation) in this amplitude by about (400 %). For single pile, and under the same operating frequency, a small decrease in the amplitude of vertical vibration resulted from increasing the length of the pile.

Development of Small Hydraulic Downhole Motors for Well Drilling Applications

Further development of the well drilling technologies becomes possible due to the improvement of rock cutting tools and hydraulic downhole motors. When developing a new hydraulic motor, it is highly important to eliminate rotor vibrations and reduce motor size. There are two main trends in further improvement of hydraulic motors: The upgrade of the downhole screw motors currently in use and the development of new reliable geared turbodrills. Besides, the R&D works are underway to construct a roller vane motor for downhole drilling. The experts of Gubkin Russian State University of Oil and Gas have launched a new R&D programme aiming at developing a hybrid hydraulic system combining the best features of a screw motor and a roller vane motor. The hybrid hydraulic system could be a radical solution to the problem of rotor vibrations in a hydraulic motor. The R&D activities conducted by Gubkin Russian State University of Oil and Gas are intended to create an advanced downhole drilling motor for the cutting tools with high-torque bits rotating at a speed of 240 to 450 rpm. The main area of application of the hybrid hydraulic motor is horizontal drilling of oil and gas fields. Yet, some R&D findings can be used for performing other production tasks, e.g., designing the pumping facilities for oil and gas extraction and pumping.

A New Stray-Load Loss Formula for Small and Medium-Sized Induction Motors

This paper proposes a new stray-load loss (SLL) formula for small and medium induction motors (IMs) based on tests data of a 182, 60 Hz IMs in the range of 1–500 hp (0.75–375 kW). They are all tested in accordance with IEEE Std 112-Method B. The proposed formula is validated by recalculating the efficiency of the same number of motors by using the proposed formula, as well as the IEEE Std 112 and the IEC 60034-2-1 standards. Another validation was done on testing 17 additional IMs that are independent of the 182-motor data. In both validations, the new formula demonstrates better accuracy. This formula shows the potential to replace the existing SLL estimation formula for this horsepower range.