Three-phase cables in a motor driving system are the major ways of electromagnetic radiation, which result in potential interference to the nearby electronic equipment on electric vehicle. Numerical simulation of radiated emissions from cables is time-consuming, which becomes insufficient to compute large numbers of cables for actual applications. Hence, this article proposes a fast prediction approach that can highly improve the computational efficiency. Since cables are often close to each other and arbitrarily bent in the real application due to confined working space, the influence of proximity effects caused by closely-spaced cables on radiated emissions is also considered in the calculation model by multi-transmission line and Hertzian dipole theories. Besides, an equivalent model is presented to characterize the measured motor impedance. On the basis of the proposed cables model, a complete motor driving system model is originally developed by integrating a radiated electromagnetic interference (EMI) source model of inverter and a load equivalent model of motor impedance. The system model is of vital value to identify the mechanism concerning radiated EMI issues on electric vehicles and efficiently evaluated in the end. Both numerical simulations and experiments are conducted for the validation of proposed approach, which show that the proposed approach can save over 90% computational time with desired evaluation accuracy.

Radiated emission from electric motors interferes nearby electronic devices and, thus, degrades the electromagnetic compatibility performance of the systems. Establishing a full-wave model of electric motor is crucial to full understanding of the radiated emission. Nevertheless, challenges remain in modeling large quantities of winding wires that hinders the establishment of a full-wave model. In particular, the proximity effects of closely spaced winding wires can strongly affect their radiation characteristics by changing the charge distributions on wires, which should be critically considered in the reduction modeling. In this article, the geometrical and electrical characteristics considering proximity effects are first generated by deriving the per-unit-length capacitance matrix of wires, and a four-step reduction procedure is detailed to simplify the complete wires model influenced by proximity effects. Backpropagation (BP) neural network is used for the first time to compute the geometrical characteristics of reduced wires model. Our results show that the reduced model has identical radiation characteristics with the complete model, as such it can be applied to develop a full-wave electric motor model for the prediction of radiated emissions. The validation of our technology is testified both numerically and experimentally.

Axial flow fans, used for heat dissipation in electronic equipment, may generate significant electromagnetic interference during PWM speed regulation. Due to its multiple radiation sources and relatively smaller size compared to the equipment, the radiation prediction model for equipment-level EMC analysis often involves a huge number of grids, which leads to computational difficulties and inefficiencies, and thus an equivalent modeling method for the electromagnetic radiation of PWM fan is presented. First, a detailed field-circuit coupling model of the radiation from winding and driving circuits is established using the time-domain finite-integral method with non-uniform grids. Then, a near-field hexahedron is defined to surround the fan, and the electromagnetic field of all its surfaces is derived based on the Huygens principle and calculated. Finally, the hexahedron encapsulating all radiation sources within the fan can be used in a higher level simulation as replicable and reusable equivalent sources. The proposed method is validated by a numerical example and actual measurements and applied to predict the radiation emissions within an electronic enclosure. The results show that the equivalent model can reduce 81.4% computation time and maintain good consistency in comparison to the detailed field-circuit coupling model.

In this paper, two kinds of high gain and low sidelobe emission array antennas are presented. The two kinds of array antennas are designed by dloph-chebyshev synthesis and Taylor synthesis respectively, microstrip array antenna is obtained by designing microstrip feed network with unequal amplitude power divider. The simulation results show that the transmitter array antenna using dloph-chebyshev synthesis method at 5.8GHz has 23.2 dBi gain, the beam Angle of plane yoz and xoz is respectively 12° and 12°, and the transmitter array antenna using Taylor synthesis method at 5.8GHz has 23.3 dBi gain, the beam Angle of face plane yoz and xoz is respectively 11° and 12°, two kinds of high gain and low side lobe emission array antennas have good performance. They can be used in wireless energy transmission.

Axial flow fans are widely used for heat dissipation in electronic devices. Due to its frequent speed-regulation to adapt to the change in heat load, a fan can cause significant electromagnetic radiation interference. In this study, a peak absorption filtering method is proposed to address the radiation interference issue in a high-speed PWM axial flow fan. The mechanism and coupling paths of radiation interference were analyzed, and a radiation interference calculation using finite integration technique by a hybrid field-circuit model and experimental measurement were conducted to identify the winding as the main source of radiation in PWM fan. Considering the limited space inside the fan, an integrated, non-inductive filtering circuit was designed to absorb the peak voltage entering the windings and the filter parameters are determined via circuit simulation. The measurement results indicate that the filtering method can reduce overall electromagnetic interference with a maximum peak reduction of 41.9 dB, without affecting the useful signals.