Development of Slot-Less Linear Oscillatory Actuator

Linear Oscillatory Actuator (LOA) is an electromechanical device that can produce short linear stroke motion directly without the use of any mechanical transmission to convert rotary motion into linear motion. Due to this simplicity, the benefits of LOA over conventional actuator are simple structure, better dynamical performance, and higher reliability. It has been extensively used in industry applications especially in power generation, healthcare, factory automation, and household appliances. Currently, most of the researches are only dealing with designing a slot type of LOA with exact values of thrust, electrical time constant, and mechanical time constant. Some of them studied the control strategy of an existing moving coil type of LOA. But, none of them had disclosed information about the oscillation displacement characteristics based on various sizes of LOA. Such information is useful for the designer. It will provide solutions or guidelines about the thrust constant, spring constant, electrical time constant, and mechanical time constant toward oscillation displacement characteristics of LOA. The analysis of the parameters mentioned above definitely will help any researchers to know whether the LOA is suitable for the specific application before design the optimized structure for fabrication. Unfortunately, the information as mentioned above is not available to the designers. This thesis describes the development and analysis on the effect of thrust constant, spring constant, electrical time constant, and mechanical time constant to oscillation displacement characteristic of slot-less linear oscillatory actuator. The analysis is necessary to determine the variation and relationship of these constants to various sizes of LOA. In this research, a prototype of slot-less linear oscillatory actuator is designed using Finite Element Method (FEM). The prototype is fabricated and measured experimentally. Moreover, analytical solution is developed for the same prototype using Permeance Analysis Method (PAM). The two methods were verified through comparison with measurement. The comparison shows the proposed analytical solution using PAM had good agreement with both FEM and the measurement. As summary, the research found that the constants affect the oscillation displacement to be higher but the thrust would become lower for small size of LOA. In contrary, high thrust can be achieved for bigger size of LOA but the oscillation displacement would become lower. Therefore, in order to design high thrust LOA the lower value of electrical time constant and mechanical time constants should be selected. Meanwhile, for both thrust constant and spring constant higher value should be selected. For designing higher oscillation displacement of LOA, the lower value of electrical time constant, thrust constant, and spring constant should be selected where as for mechanical time constant higher value should be selected

Effects of wing size on magnetic levitation using coil induced field

The paper discusses the effect of wing size on magnetic levitation using coil induced field for a proposed Levitator Guide (LG). The levitation consists of two main parts namely permanent magnet and current carrying copper coils. The variation of these parts may effects the produced levitated force. A few models have been analyzed with simulation. Results indicated that levitator guide model of wings with centered elbow give rise to the desired performance. Finally, a new type of levitator guide is proposed and fabricated

Flux Modulated Rotating Pole Piece Magnetic Gear

In this paper, the CMG is re-condition so that the pole piece act as the outer rotor instead of surface mount PM. This magnetic coupling of the CMG is similar to the conventional CMG which uses harmonic to transfer the torque and speed from the inner rotor to the outer rotor. The working principle of the proposed CMG is derived analytically and simulated using finite element software. For this recondition, the PM at the outer section become stationary hence, retaining sleeve can be removing. The proposed MG produced 18% higher average torque than the conventional MG with drawback in torque ripple. The proposed CMG also produce higher gear ratio than the same pole pair of conventional CM

Preliminary Magnetization Pattern Study On Magnetic Gear

In this paper, radial anisotropic, circumferential anisotropic, parallel circular direction (PCD) and parallel radial direction (PRD) magnetization pattern are introduced and explained. Then, these magnetization pattern are simulated using JMAG Designer 16.0 on the coaxial magnetic gear with 2.33 gear ratio. Torque and efficiency are calculated and compared. The result shows that the radial anisotropic produce the highest torque and register the best efficiency versus the latter.With this study, it is hope that the designer can have second option to choose other type of magnetization without sacrificing the performance. The option may become in handy when the RAP becomes more expensive or difficult to procur

A New Speed Multiplier Coaxial Magnetic Gear

Due to certain conditions, electrical motor (EM) that operates at high speed may lead to magnetic saturation, thermal issue, and stress to rotor structure. Magnetic gear (MG) designed for speed multiplier enables the prime mover from EM to operate at lower speed while the output gear multiplies the speed by its designated gear ratio at reduced torque. In this paper, a new coaxial magnetic gear is designed for speed multiplier. The role between inner yoke with PM and pole piece is switched. The inner part of magnetic gear is made to be stationary while the pole piece becomes inner rotor. The working principle is presented analytically based on flux modulation techniques for torque and speed transmission. Torque characteristic and gear efficiency are analysed using finite element and compared with existing speed multiplier magnetic gear with the same gear ratio of 7/3. Based on the simulation result, the proposed speed multiplier MG offers 16% better torque density and 12% higher gear efficiency at higher speed range. The structure of the inner rotor is also found to be more robust as only pole piece ring together with plastic holding frame is rotated instead of yoke with P

Design Of A Linear DC Motor For High Thrust Constants Characteristics

Traditionally a linear motion system consists of a rotational motor and motion translation component. However, the traditional systems inherit several drawbacks that contribute into operational limitation. Currently, use of a linear motor is seen as an alternative to produce direct linear motion without use any motion translation. Linear DC Motor (LDM) is one type of linear motor. Previously, a LDM has been developed to be use in a linear displacement system. Based on experimental result, it could achieve a desired displacement with fast settling time and low overshoot. However, in order to improve the system performance especially in term of time response, a new LDM need to be designed. In this paper, a LDM for similar application was designed. The shape of the LDM has been change from a rectangular to quarter circle due to changes in shape of permanent magnet. Furthermore, material of the permanent magnet also has been changed from ferrite to NdFeB to increase the magnetic flux density in air gap. Based on the designed, the LDM has produce about 3.1 N/A and 35.12 ms in term of thrust constant, kf and mechanical time constant, Tm respectively. In comparison with previous LDM, it only produced about 1.6 N/A and 111.72 ms in term of thrust constant, kf and mechanical time constant, Tm respectively

Preliminary analysis of eddy current and iron loss in magnetic gear in electric vehicle

The inclusion of a high energy density permanent magnet into magnetic gear improves the machine's torque density. However, it also contributes to eddy current loss, especially in a high-speed application such in electric vehicle. In this paper, the losses from eddy current and iron loss are investigated on concentric magnetic gear (CMG). Torque multiplier CMG is designed with 8/3 gear ratio for this study. Iron loss and eddy current loss are compared and discussed. Based on this study, eddy current loss contributes to almost 96% of the total loss. This finding is hoped to direct the researcher to focus more on reducing loss associated with eddy current loss

Winding Arrangement Of A New Type Hollow Rotor BLDC Motor

This paper discusses about winding arrangement of fractional slot of a new type hollow rotor Brushless Direct Current (BLDC) motor. Hollow rotor has higher performance compared to other BLDC motor because it minimizes the unused flux below permanent magnet and maximize torque produce by the motor. It’s also known that 8 pole motor is favorite used in industrial because it has an optimum space of permanent magnet for a smaller motor size. The number of pole will affect the maximum speed of the rotor. Thus, the objective of this research is to investigate the best winding arrangement for 8 pole of hollow rotor that could produce the highest electromagnetic performance. At starts, four combinations of slot number and coil sizes had been selected. Structural comparison in term of coil vector and winding arrangement is studied. Finite Element Method (FEM) had been used to simulate the parameters such as backemf and torque waveforms. It was convinced that 9 slot 8 pole with 0.6 size of coil produces the best performance. The confirmed model had been fabricated and measured. Both results from FEM and measurement are compared in term of backemf and torque where percentage differences are 7.4 % and 8 %, respectively. As conclusion, this research shows the fundamental of winding arrangement of fractional slot of motor especially 8 pole motor

Comparison on thrust characteristic of linear oscillatory actuators

This paper is aimed to analyze the thrust characteristics for two types of Linear Oscillatory Actuator using 3D-Finite Element Method (FEM). The coil currents are analyzed according to the variation displacement of moving yoke of the first one of the LOA. The thrust, normal force and cogging force are analyzed according to the variation of the airgap length, thickness taper and high taper of second LOA. The size of both model of LOA is same but comparison refers to the characteristic of voltage, coil current, number of winding and force. The result of this project can be see from the graph of characteristic both model. Finally, the best characteristics of LOA can be constructed from the result