Papers by Keyword: Eddy Current Loss

Abstract: This paper presents an implementation of square wave drive on super-high-speed PMSM. In order to solve the problem that the rotor temperature of super-high-speed PMSM rises sharply, this paper compares SVPWM method with square wave method and designs a pre-BUCK PMSM drive. The new drive uses sensorless control algorithm and gets the position signal from BEMF. The simulation and experiment results are shown to exhibit the performance of the drive. The experiments are conducted at speeds up to 50000rpm and the results show that the drive can restrain the rotor temperature from rising remarkably.

Abstract: The non-linear relationship between the magnetic field intensity and magnetostrictive strain which is caused by the thermal expansion produced by the eddy current loss in the GMM rod, will affect the precision and stability of GMM actuator. This paper tries to reduce the eddy current loss in the GMM rod to improve the performance of magnetostrictive actuator by machining radial grooves in the surface of the rod. The numerical results show that the axial grooves can be effective in reducing thermal power loss. The groove size and number are both optimized by numerical method. The results show that the groove depth and number has great impact on the unit volume eddy current loss while the groove width has little or no impact. The test of the magnetostrictive strain shows that the linearity of the GMM rod with grooves is significantly improved. The radial grooves in the GMM surface can reduce the eddy current loss and improve the performance of GMM actuator.

Abstract: A novel dynamic electromagnetic induction heater for water treatment system is introduced in this paper, and its structure and operation mechanism is given. The heater converts input mechanical energy into various forms of heat energy completely, including the hyseresis loss, eddy current loss, copper loss and so on, and the mathematical model of loss is established based on fundamental electromagnetic field theory. By the finite element analysis, the above three kinds of loss are calculated at different rotation speed, as well as each of the percentage of total loss. At last, the temperature field and heat flux distribution of heater are calculated.

Abstract: The problem about the eddy current loss which is caused by leakage magnetic field in ultrahigh pressure large capacity power transformer is becoming more extrusive. It is very significant to research the power transformer leakage magnetic field and eddy current loss on the tank wall thoroughly and accurately. 3D finite element model of power transformer leakage magnetic field and eddy current loss is established in this paper, the eddy current loss on the tank wall is calculated and the distribution is analyzed. For the eddy current loss could be reduced by magnetic shielding, new calculation model are established respectively, then eddy current loss on tank wall could be got with shielding. The best size and location of the shielding could be analyzed after changing the height of the shielding, which provided the important evidence to reduce tank wall eddy current loss effectively. The calculating methods have been proved to be accuracy after experiment.

Abstract: It is important to clarify the rotor eddy current losses in bearingless permanent magnet synchronous (BPMSM) for temperature rising to induce irreversible demagnetization. In this paper, the torque and radial suspension force producing mechanisms of BPMSM are introduced. The relative motion relationships among radial suspension force, rotor magnetic field and suspension winding magnetic field are analyzed. The necessary conditions of producing stable controllable radial suspension force in single direction are concluded. The rotor eddy current losses in BPMSM with PB=PM+1 and PB=PM-1 are calculated and compared using 2D time-steeping finite element method. The research results have shown that the BPMSM with PB=PM+1 is the most suitable for high speed operation with the minimum eddy current losses in rotor.

Abstract: This paper proposes a new estimation for the eddy-current loss of MnZn ferrite cores. The eddy-current loss plays a critical role in the frequency range of 100-500 kHz, whereas the amount of the hysteresis loss dominates the core loss of magnetic devices below 100 kHz. However, the definition and calculation of eddy-current loss are not as easy or accurate. In the proposed estimation, the equivalent electrical circuit method is conducted for determining the grain conductivity and the driving current to replace the induced magnetic flux density in order to simplify measurement. The related electrical and magnetic characteristics are measured by an HP-4294 impedance analyzer. Finally, an EI30 (PC40 material system from TDK) MnZn ferrite core is used as an example to prove that this model can effectively estimate the eddy-current loss of MnZn ferrite cores at different frequencies and driving currents

Abstract: With the advent of power electronic technology, the excitation conditions applied to transformers, motors, etc. could be very atypical. DC bias excitation is an undesired working condition of AC power transformers, the asymmetrical saturation of the transformer core, the heavy noise, the serious vibration, and the local loss concentration can all potentially occurred in dc-biased transformers. The effect of the exciting current under different dc-biased magnetization on eddy-current loss in copper plate based on a reduced engineering-oriented benchmark model (TEAM Problem 21) is investigated. Experiment scheme for dc biasing is presented and the distribution of the eddy current loss under different dc-biased excitation conditions was studied in detail. The engineering applicability of three dimensional eddy current analysis methods for dc-biased magnetization field computation and the practical loss modeling are examined, which has been demonstrated via the numerical modeling results and the measured data.

Abstract: The Fe-Si-Al soft magnetic composites were produced by cold pressing of water-atomized Fe-Si-Al powder using organic binder. The effect of shaping pressure, annealing temperature, magnetic annealing and dielectric content on properties of Fe-Si-Al soft magnetic composites was investigated. The results showed that increasing shaping pressure increases density and radial crushing strength of Fe-Si-Al soft magnetic cores, and decreases coercivity and total loss. Increasing annealing temperature can increase effective permeability and decrease total loss owing to decreasing hysteresis loss, and over-annealing (＞660°C) can deteriorate magnetic properties. The magnetic annealing can decrease total loss of Fe-Si-Al magnetic powder core. Increasing dielectric content can reduce the eddy current loss of Fe-Si-Al magnetic powder core and decrease the real part of permeability. Fe-Si-Al magnetic powder core with shaping pressure of 1800 MPa, annealing temperature of 660 °C and dielelctric content of 0.7% presented the optimum magnetic properties with an effective permeability of 127, a total loss of 78mW/cm3 and a radial crushing strength of 18MPa.

Abstract: This paper presents comparative results of an electromagnetic study performed in two different wound core transformer configurations in order to know the best configuration that reduce excitation current and core losses. The results show that octagonal wound-core (OWC) reduces the excitation current and eddy-current losses with respect conventional-wound core (CWC). The results were obtained applying 2D and 3D FEM simulations, taking into account the non-linear properties of the core. In the last part of this paper, several grades of grain oriented electrical steels and the combination of them are analyzed to find the best mixing percentage to reduce eddy-current losses and excitation current.

Abstract: The Nd:YAG laser welding experiments of Hastelloy C-276 was presented and the results of experiments were discussed which reflect the rise of electric resistivity of the sample. In addition, a mathematic model of 2-D nonlinear eddy current field for motor of the nuclear reactor coolant pump with the Hastelloy C-276 can was simulated which provides the concrete effect of electric resistivity change on the eddy current losses of cans. It was found that the eddy current losses of the motor can were decreased as the increase of electric resistivity of can. Then, the advantage of laser welding on the molding of motor can was discussed which not only does not destroy the electric performance of Hastelloy C-276 but enhances it and declines the eddy current losses of can forming with it.