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In this article, a clear and concise analytical method for predicting the performance of a Liquid-cooling eddy current brake (LC-ECB) is proposed. The LC-ECB has a coolant channel in the rotor to allow direct cooling of the inner surface of the stator. The static air-gap magnetic field distribution is obtained by the dynamic magnetic equivalent circuit (MEC) method, and the magnetic flux leakage and global magnetic saturation effects are fully considered. The magnetic field intensity distribution function of the eddy current reaction magnetic field is derived for the first time based on Ampere circuital theorem. Considering the local magnetic saturation and skin effect, a novel double-iteration algorithm based on the conservation principle of magnetic pressure drop is applied to obtain the transient air-gap flux density distribution, and then the brake torque expression is obtained. The finite element method (FEM) and experimental results show that the proposed method is feasible and effective. The new model is easy to program and can be easily used in the initial design and optimization of LC-ECB. [ABSTRACT FROM AUTHOR]

In this article, a clear analytical model for predicting the performance of permanent magnet (PM) eddy current couplers is proposed. The interaction of the reaction magnetic fields between adjacent eddy current rings was considered for the first time. Based on a magnetic equivalent circuit (MEC) and the Ampere circuital theorem, the accurate distribution of the air gap magnetic field under different slip velocities was deduced in a 2-D model, and the analytical expression of the transmission torque was obtained. 3-D effects were also taken into account to calibrate the model. The validity of the analytical model was verified by comparison with results from the 3-D finite element method (FEM). The comparison shows that the analytical model can accurately predict the magnetic field distribution and transmission torque over a wide range of slip velocity variations. This model can greatly reduce the number of calculations required and save time, and it is suitable for the preliminary design and optimization of PM eddy current couplers. [ABSTRACT FROM AUTHOR]

To both overcome the serious thermal recession problem and conserve energy for conventional eddy-current brakes, a self-excited and liquid-cooled electromagnetic retarder (SL-EMR) assembly is proposed. The design includes a stator with an internally cooled channel, a rotor with multiple magnetic heads, and an integrated generator without brushes. The assembly and operating principles are analyzed. Models of the braking and generating systems are established. The electromagnetic field model analysis, braking performance analysis, thermal field analysis, and generator characteristic analysis of the SL-EMR are simulated using the finite-element method (FEM). The SL-EMR performance is bench tested, and the results show a 6% difference between the FEM results and the experimental results. The integrated generator provides adequate exciting current for the braking system. The braking torque decreases by only 10.4% during continuous braking conditions. The braking torque reached 2000 \N\cdot \m when the speed was 1500 r/min and the coil current was 30 A. [ABSTRACT FROM PUBLISHER]

To overcome the serious thermal recession problem that has been associated with the braking torque of conventional eddy current brakes, and to conserve energy, this paper has proposed a novel self-excited eddy current retarder (S-ECR). The design includes a stator with an internally cooled channel, a rotor with double salient poles, and a built-in generator. The electromagnetic field analysis and the performance analysis of the S-ECR were carried out using the finite-element method. The S-ECR performance was tested at a test bench. The test results showed that the calculated braking torque and the generator performance were in reasonable agreement with the measured results. The braking performance did not obviously diminish during the continuous braking stage. When the speed was 1500 r/min and the exciting current was 30 A, the braking torque could reach 1600 N·m. [ABSTRACT FROM AUTHOR]

A liquid-cooled eddy current retarder (ECR) with a dual salient poles design is proposed in this paper. Finite element models were developed to perform transient magnetic analysis and steady-state conjugate heat transfer analysis. The braking torque, eddy current field and thermal field of the retarder were each predicted. The retarder was subjected to two sets of tests on a test bench, to obtain the braking torque at various rotational speeds, while utilizing two different magnetomotive forces, respectively, and the torque was also tested while maintaining a constant rotational speed, for a specific amount of time. The good agreement shown between the calculations and measured data of the braking torque served to validate the analysis method. The experiments also showed that the braking torque of the retarder decreased more slowly than the braking torque of conventional ECRs in continuous operation. [ABSTRACT FROM AUTHOR]

This paper proposes a novel permanent magnet retarder (PMR) structure that uses water cooling to improve the braking performance of conventional PMR for heavy vehicles. A finite element model for a water-cooled PMR was developed by considering the temperature dependence of magnetic characteristics and heat conductivity. The eddy current and temperature distribution were analyzed using the magneto-thermal coupled method. Retarder performance was tested at a test bench. The test results show that the calculated temperature and braking torque agreed fairly well with the measured results. PMRs can maintain a low working temperature by using water cooling. Compared with air-cooled retarder, this retarder's braking torque does not decrease much under continuous working conditions. [ABSTRACT FROM PUBLISHER]

This paper presents a new microactuator using a phase change material (PCM) composite with induction heating. The PCM composite is consisting of paraffin wax, expanded graphite and nickel particle, which was used as an electrical conductive phase change material with improved magnetic permeability. Expanded graphite was used as an electrical conductive porous matrix absorbed with paraffin wax and nickel particle. This work relies on induction heating generated in the PCM composite with eddy current, rather than using external resistive heater. Experiments show that about 140   μ m actuation height was realized in 5 s with the input power of 1.42 W at excitation frequency of 1 kHz. Since an induction heating method is adopted with electrical conductive PCM composite, which means the new microactuator has no wire or electrodes to connect with the conductive PCM composite. The new PCM-composite-based microactuator has some advantages, such as ease of fabrication, small-sized, low cost, and eases of integration into Micro-Electro-Mechanical Systems (MEMS). [ABSTRACT FROM AUTHOR]