Fiber reinforced materials are widely used in many products because of their excellent mechanical and chemical properties. The fiber types include rebar, wire, polypropylene fiber and carbon fiber, etc., and the fiber diameter ranges from millimeter to micrometer level. However, fiber reinforced materials are followed by a large number of electromagnetic shielding problems, especially for products in aerospace and other fields. And the reflection characteristics greatly affect the shielding performance of the material. Therefore, it is very important to evaluate the reflection characteristic of products by electromagnetic simulation. Due to the complex microstructure of fiber reinforced materials, direct modeling is very difficult and computationally expensive. Based on the existing multi-layer equivalent modeling method, this paper optimizes the layered method, and proposes an equivalent layer model modeling method when the number of layers is small. The idea of this method is to minimize the difference between the equivalent model and the actual structure through non-uniform thickness stratification, so as to improve the equivalent accuracy under the condition of the same number of segmentation layers. Finally, a series of simulations based on selected structural parameters and frequency range are carried out to compare the simulation results of the proposed method with those of the existing methods, and the results prove the effectiveness of the proposed method. Moreover, the conclusion obtained by this method is still valid when the structure size parameters, wavelength and electrical conductivity are proportionally changed according to the theory of electromagnetic wave propagation.

In order to improve the immunity and stability of dc-dc converters in industrial production, a discrete adaptive super-twisting sliding mode algorithm is proposed in this paper. Firstly, a linear gain term is introduced into the conventional algorithm to improve discrimination accuracy of the system. Secondly, for the complexity and constraints of the gain parameters in the sliding mode algorithm, this paper designs a voltage-based time-varying function instead of multiple gains in the model, and demonstrate the stability of the proposed finite-time observer algorithm through Liapunov stability theorem. Finally, simulations and experiments were conducted on the proposed algorithm, demonstrating that the finite time super twist sliding mode control algorithm proposed in this paper can effectively reduce the impact of load changes on the output voltage.

To address the issue of low conversion efficiency in DC-DC Boost converters under heavy load, this paper utilizes a technique of adaptive on-resistance control for power MOSFETs. By setting different drive voltages in different load ranges, the on-resistance of power MOSFETs is reduced, addressing the issue of significant conduction loss at heavy loads. In addition, using pulse skipping modulation (PSM) and partially turning off power MOSFETs can improve the system’s conversion efficiency at light loads. Based on 0.18μm BCD technology, specific verification of this method was completed in an actual chip. The results show that with an input voltage of 3.7V, output voltage of 5V, and operating frequency of 1.5MHz within a wide load range from 10mA to 900mA, the system can adaptively adjust the on-resistance of power MOSFETs. This increases efficiency from 83% to 91.7% when the load current equals 900mA and achieves efficiencies above 90% across the entire load range, with a peak efficiency reaching 96.5%.

In order to reduce the fluctuation range of output speed and torque of permanent magnet synchronous motor at high speed, this paper proposes an improved flux-weakening control method of single current regulator of permanent magnet synchronous motor. Based on chaotic mapping and Monarch Butterfly Optimization, an adaptive chaos monarch butterfly optimization is proposed to use for online parameter identification. This algorithm generates a chaotic sequence distributed according to a specific pattern through a single chaotic mapping, and combines it with the results of the previous parameter identification to generate an initialized population. Secondly, the impact mechanism of different load curve positions on the smoothness and efficiency of motor operation was analyzed, and the influence of motor parameters on voltage limited elliptical distortion was analyzed. Finally, a method of giving the cross-axis voltage considering motor parameters is designed. The simulation and experimental results show that the parameters of the motor can be accurately identified online based on ACMBO. When the load is 85 N･m, the range of motor torque output error is effectively reduced.